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1.  Capnography during cardiopulmonary resuscitation: Current evidence and future directions 
Capnography continues to be an important tool in measuring expired carbon dioxide (CO2). Most recent Advanced Cardiac Life Support (ACLS) guidelines now recommend using capnography to ascertain the effectiveness of chest compressions and duration of cardiopulmonary resuscitation (CPR). Based on an extensive review of available published literature, we selected all available peer-reviewed research investigations and case reports. Available evidence suggests that there is significant correlation between partial pressure of end-tidal CO2 (PETCO2) and cardiac output that can indicate the return of spontaneous circulation (ROSC). Additional evidence favoring the use of capnography during CPR includes definitive proof of correct placement of the endotracheal tube and possible prediction of patient survival following cardiac arrest, although the latter will require further investigations. There is emerging evidence that PETCO2 values can guide the initiation of extracorporeal life support (ECLS) in refractory cardiac arrest (RCA). There is also increasing recognition of the value of capnography in intensive care settings in intubated patients. Future directions include determining the outcomes based on capnography waveforms PETCO2 values and determining a reasonable duration of CPR. In the future, given increasing use of capnography during CPR large databases can be analyzed to predict outcomes.
doi:10.4103/0974-2700.142778
PMCID: PMC4231274  PMID: 25400399
Capnography; cardiac arrest; cardiopulmonary resuscitation; end-tidal carbon dioxide
2.  Prehospital determination of tracheal tube placement in severe head injury 
Emergency Medicine Journal : EMJ  2004;21(4):518-520.
Methods: All adult patients (>18 years) with severe head injury, maxillofacial injury with need of protection of airway, or polytrauma were intubated by an emergency physician in the field. Tube position was initially evaluated by auscultation. Then, capnometry and capnography was performed (infrared method). Emergency physicians evaluated capnogram and partial pressure of end tidal carbon dioxide (EtCO2) in millimetres of mercury. Determination of final tube placement was performed by a second direct visualisation with laryngoscope. Data are mean (SD) and percentages.
Results: There were 81 patients enrolled in this study (58 with severe head injury, 6 with maxillofacial trauma, and 17 politraumatised patients). At the first attempt eight patients were intubated into the oesophagus. Afterwards endotracheal intubation was undertaken in all without complications. The initial capnometry (sensitivity 100%, specificity 100%), capnometry after sixth breath (sensitivity 100%, specificity 100%), and capnography after sixth breath (sensitivity 100%, specificity 100%) were significantly better indicators for tracheal tube placement than auscultation (sensitivity 94%, specificity 66%, p<0.01).
Conclusion: Auscultation alone is not a reliable method to confirm endotracheal tube placement in severely traumatised patients in the prehospital setting. It is necessary to combine auscultation with other methods like capnometry or capnography.
PMCID: PMC1726371  PMID: 15208251
3.  Partial pressure of end-tidal carbon dioxide successful predicts cardiopulmonary resuscitation in the field: a prospective observational study 
Critical Care  2008;12(5):R115.
Introduction
Prognosis in patients suffering out-of-hospital cardiac arrest is poor. Higher survival rates have been observed only in patients with ventricular fibrillation who were fortunate enough to have basic and advanced life support initiated soon after cardiac arrest. An ability to predict cardiac arrest outcomes would be useful for resuscitation. Changes in expired end-tidal carbon dioxide levels during cardiopulmonary resuscitation (CPR) may be a useful, noninvasive predictor of successful resuscitation and survival from cardiac arrest, and could help in determining when to cease CPR efforts.
Methods
This is a prospective, observational study of 737 cases of out-of-hospital cardiac arrest. The patients were intubated and measurements of end-tidal carbon dioxide taken. Data according to the Utstein criteria, demographic information, medical data, and partial pressure of end-tidal carbon dioxide (PetCO2) values were collected for each patient in cardiac arrest by the emergency physician. We hypothesized that an end-tidal carbon dioxide level of 1.9 kPa (14.3 mmHg) or more after 20 minutes of standard advanced cardiac life support would predict restoration of spontaneous circulation (ROSC).
Results
PetCO2 after 20 minutes of advanced life support averaged 0.92 ± 0.29 kPa (6.9 ± 2.2 mmHg) in patients who did not have ROSC and 4.36 ± 1.11 kPa (32.8 ± 9.1 mmHg) in those who did (P < 0.001). End-tidal carbon dioxide values of 1.9 kPa (14.3 mmHg) or less discriminated between the 402 patients with ROSC and 335 patients without. When a 20-minute end-tidal carbon dioxide value of 1.9 kPa (14.3 mmHg) or less was used as a screening test to predict ROSC, the sensitivity, specificity, positive predictive value, and negative predictive value were all 100%.
Conclusions
End-tidal carbon dioxide levels of more than 1.9 kPa (14.3 mmHg) after 20 minutes may be used to predict ROSC with accuracy. End-tidal carbon dioxide levels should be monitored during CPR and considered a useful prognostic value for determining the outcome of resuscitative efforts and when to cease CPR in the field.
doi:10.1186/cc7009
PMCID: PMC2592743  PMID: 18786260
4.  End-tidal carbon dioxide monitoring during bag valve ventilation: the use of a new portable device 
Background
For healthcare providers in the prehospital setting, bag-valve mask (BVM) ventilation could be as efficacious and safe as endotracheal intubation. To facilitate the evaluation of efficacious ventilation, capnographs have been further developed into small and convenient devices able to provide end- tidal carbon dioxide (ETCO2). The aim of this study was to investigate whether a new portable device (EMMA™) attached to a ventilation mask would provide ETCO2 values accurate enough to confirm proper BVM ventilation.
Methods
A prospective observational trial was conducted in a single level-2 centre. Twenty-two patients under general anaesthesia were manually ventilated. ETCO2 was measured every five minutes with the study device and venous PCO2 (PvCO2) was simultaneously measured for comparison. Bland- Altman plots were used to compare ETCO2, and PvCO2.
Results
The patients were all hemodynamically and respiratory stable during anaesthesia. End-tidal carbon dioxide values were corresponding to venous gases during BVM ventilation under optimal conditions. The bias, the mean of the differences between the two methods (device versus venous blood gases), for time points 1-4 ranges from -1.37 to -1.62.
Conclusion
The portable device, EMMA™ is suitable for determining carbon dioxide in expired air (kPa) as compared to simultaneous samples of PvCO2. It could therefore, be a supportive tool to asses the BVM ventilation in the demanding prehospital and emergency setting.
doi:10.1186/1757-7241-18-49
PMCID: PMC2949667  PMID: 20840740
5.  A feasibility study on bedside upper airway ultrasonography compared to waveform capnography for verifying endotracheal tube location after intubation 
Background
In emergency settings, verification of endotracheal tube (ETT) location is important for critically ill patients. Ignorance of oesophageal intubation can be disastrous. Many methods are used for verification of the endotracheal tube location; none are ideal. Quantitative waveform capnography is considered the standard of care for this purpose but is not always available and is expensive. Therefore, this feasibility study is conducted to compare a cheaper alternative, bedside upper airway ultrasonography to waveform capnography, for verification of endotracheal tube location after intubation.
Methods
This was a prospective, single-centre, observational study, conducted at the HRPB, Ipoh. It included patients who were intubated in the emergency department from 28 March 2012 to 17 August 2012. A waiver of consent had been obtained from the Medical Research Ethics Committee. Bedside upper airway ultrasonography was performed after intubation and compared to waveform capnography. Specificity, sensitivity, positive and negative predictive value and likelihood ratio are calculated.
Results
A sample of 107 patients were analysed, and 6 (5.6%) had oesophageal intubations. The overall accuracy of bedside upper airway ultrasonography was 98.1% (95% confidence interval (CI) 93.0% to 100.0%). The kappa value (Κ) was 0.85, indicating a very good agreement between the bedside upper airway ultrasonography and waveform capnography. Thus, bedside upper airway ultrasonography is in concordance with waveform capnography. The sensitivity, specificity, positive predictive value and negative predictive value of bedside upper airway ultrasonography were 98.0% (95% CI 93.0% to 99.8%), 100% (95% CI 54.1% to 100.0%), 100% (95% CI 96.3% to 100.0%) and 75.0% (95% CI 34.9% to 96.8%). The likelihood ratio of a positive test is infinite and the likelihood ratio of a negative test is 0.0198 (95% CI 0.005 to 0.0781). The mean confirmation time by ultrasound is 16.4 s. No adverse effects were recorded.
Conclusions
Our study shows that ultrasonography can replace waveform capnography in confirming ETT placement in centres without capnography. This can reduce incidence of unrecognised oesophageal intubation and prevent morbidity and mortality.
Trial registration
National Medical Research Register NMRR11100810230.
doi:10.1186/2036-7902-5-7
PMCID: PMC3772703  PMID: 23826756
Bedside upper airway ultrasonography; Endotracheal intubation; Verification; Waveform capnography
6.  Correlations between capnographic waveforms and peak flow meter measurement in emergency department management of asthma 
Background
The usual method for initial assessment of an acute asthma attack in the emergency room includes the use of peak flow measurement and clinical parameters. Both methods have their own disadvantages such as poor cooperation/effort from patients (peak flow meter) and lack of objective assessment (clinical parameters). We were looking into other methods for the initial asthma assessment, namely the use of capnography. The normal capnogram has an almost square wave pattern comprising phase 1, slope phase 2, plateau phase 3, phase 4 and angle α (between slopes 2 and 3). The changes in asthma include decrease in slope of phase 2, increase in slope 3 and opening of angle α.
Aims
Our objective was to compare and assess the correlation between the changes in capnographic indices and peak flow measurement in non-intubated acute asthmatic patients attending the emergency room.
Methods
We carried out a prospective study in a university hospital emergency department (ED). One hundred and twenty eight patients with acute asthma were monitored with peak flow measurements and then had a nasal cannula attached for microstream sampling of expired carbon dioxide. The capnographic waveform was recorded onto a PC card for indices analysis. The patients were treated according to departmental protocols. After treatment, when they were adjudged well for discharge, a second set of results was obtained for peak flow measurements and capnographic waveform recording. The pre-treatment and post-treatment results were then compared with paired samples t-test analysis. Simple and canonical correlations were performed to determine correlations between the assessment methods. A p value of below 0.05 was taken to be significant.
Results
Peak flow measurements showed significant improvements post-treatment (p < 0.001). On the capnographic waveform, there was a significant difference in the slope of phase 3 (p < 0.001) and alpha angle (p < 0.001), but not in phase 2 slope (p = 0.35). Correlation studies done between the assessment methods and indices readings did not show strong correlations either between the measurements or the magnitude of change pre-treatment and post-treatment.
Conclusion
Peak flow measurements and capnographic waveform indices can indicate improvements in airway diameter in acute asthmatics in the ED. Even though the two assessment methods did not correlate statistically, capnographic waveform analysis presents several advantages in that it is effort independent and provides continuous monitoring of normal tidal respiration. They can be proposed for the monitoring of asthmatics in the ED.
doi:10.1007/s12245-009-0088-9
PMCID: PMC2700227  PMID: 20157449
Asthma; Capnography; Peak flow measurement; Emergency room
7.  Predictive Value of Capnography for Suspected Diabetic Ketoacidosis in the Emergency Department 
Introduction:
Metabolic acidosis confirmed by arterial blood gas (ABG) analysis is one of the diagnostic criteria for diabetic ketoacidosis (DKA). Given the direct relationship between end-tidal carbon dioxide (ETCO2), arterial carbon dioxide (PaCO2), and metabolic acidosis, measuring ETCO2 may serve as a surrogate for ABG in the assessment of possible DKA. The current study focuses on the predictive value of capnography in diagnosing DKA in patients referring to the emergency department (ED) with increased blood sugar levels and probable diagnosis of DKA.
Methods:
In a cross-sectional prospective descriptive-analytic study carried out in an ED, we studied 181 patients older than 18 years old with blood sugar levels of higher than 250 mg/dl and probable DKA. ABG and capnography were obtained from all patients. To determine predictive value, sensitivity, specificity and cut-off points, we developed receiver operating characteristic curves.
Results:
Sixty-two of 181 patients suffered from DKA. We observed significant differences between both groups (DKA and non-DKA) regarding age, pH, blood bicarbonate, PaCO2 and ETco2 values (p≤0.001). Finally, capnography values more than 24.5 mmHg could rule out the DKA diagnosis with a sensitivity and specificity of 0.90.
Conclusion:
Capnography values greater than 24.5 mmHg accurately allow the exclusion of DKA in ED patients suspected of that diagnosis. Capnography levels lower that 24.5 mmHg were unable to differentiate between DKA and other disease entities.
doi:10.5811/westjem.2013.4.14296
PMCID: PMC3876300  PMID: 24381677
8.  Continuous end-tidal carbon dioxide monitoring for confirmation of endotracheal tube placement is neither widely available nor consistently applied by emergency physicians 
Emergency Medicine Journal : EMJ  2005;22(7):490-493.
Objectives: To determine the availability of end-tidal CO2 measurement in confirmation of endotracheal tube placement in the non-arrest patient, and to assess its use in academic and non-academic emergency departments.
Methods: Emergency physicians in the USA were surveyed by mail in the beginning of the year 2000 regarding availability at their institution of both colorimetric/qualitative and quantitative end-tidal CO2 capnography, frequency of use in their own practice, and descriptor of their hospital (academic, community teaching, and community non-teaching). Additionally, data were obtained from the National Emergency Airway Registry 97 series (NEAR) about how many intubations used this method of confirmation. NEAR site coordinators were surveyed as well.
Results: Of 1000 surveys, 550 were returned (55%). Colorimetric technology existed in 77% of respondents' hospitals (n = 421); 25% of respondents (n = 138) had continuous monitoring capability. Physicians practising at academic hospitals were more likely to have continuous monitoring (36%; n = 196) than community teaching institutions (32%; n = 173) and non-teaching centres (18%; n = 100) (p<0.001). Among physicians who had this technology available, only 14% (n = 19) "always" used it in non-arrest intubations; 57% "rarely" or "never" employed it (n = 75). Among NEAR centres (institutions committed to monitoring current airway practices) only 12% of 6009 (n = 716) intubations used continuous end-tidal CO2 measurement. Of these practitioners, only 40% "always" used it (n = 6/15) (83% response rate (n = 29/35)).
Conclusions: Despite recommendations from national organisations that endorse continuous monitoring of end-tidal CO2 for confirming endotracheal tube placement, it is neither widely available nor consistently applied.
doi:10.1136/emj.2004.015818
PMCID: PMC1726849  PMID: 15983084
9.  End tidal carbon dioxide monitoring in prehospital and retrieval medicine: a review 
Emergency Medicine Journal : EMJ  2006;23(9):728-730.
End tidal carbon dioxide (ETCO2) monitoring is the non‐invasive measurement of exhaled CO2. The Intensive Care Society guidelines include (ETCO2) monitoring as one of the objective standards required for monitoring patients in transport, and the American Heart Association recommends that all intubations must be confirmed by some form of ETCO2 measurement. The physiological principles and technology underlying ETCO2 measurement and the clinical indication for its use in the prehospital environment are reviewed. ETCO2 monitoring has been widely established in the prehospital environment and is of particular use for verification of endotracheal tube placement. It is non‐invasive and easy to apply to breathing circuits. The units now available are compact and rugged, with extended battery operating times, which are ideally suited for prehospital use and should be considered as an essential item for advanced airway management.
doi:10.1136/emj.2006.037184
PMCID: PMC2564226  PMID: 16921096
End‐tidal; carbon dioxide; monitoring; prehospital; retrieval
10.  Noninvasive Positive Pressure Ventilation for Chronic Respiratory Failure Patients With Stable Chronic Obstructive Pulmonary Disease (COPD) 
Executive Summary
In July 2010, the Medical Advisory Secretariat (MAS) began work on a Chronic Obstructive Pulmonary Disease (COPD) evidentiary framework, an evidence-based review of the literature surrounding treatment strategies for patients with COPD. This project emerged from a request by the Health System Strategy Division of the Ministry of Health and Long-Term Care that MAS provide them with an evidentiary platform on the effectiveness and cost-effectiveness of COPD interventions.
After an initial review of health technology assessments and systematic reviews of COPD literature, and consultation with experts, MAS identified the following topics for analysis: vaccinations (influenza and pneumococcal), smoking cessation, multidisciplinary care, pulmonary rehabilitation, long-term oxygen therapy, noninvasive positive pressure ventilation for acute and chronic respiratory failure, hospital-at-home for acute exacerbations of COPD, and telehealth (including telemonitoring and telephone support). Evidence-based analyses were prepared for each of these topics. For each technology, an economic analysis was also completed where appropriate. In addition, a review of the qualitative literature on patient, caregiver, and provider perspectives on living and dying with COPD was conducted, as were reviews of the qualitative literature on each of the technologies included in these analyses.
The Chronic Obstructive Pulmonary Disease Mega-Analysis series is made up of the following reports, which can be publicly accessed at the MAS website at: http://www.hqontario.ca/en/mas/mas_ohtas_mn.html.
Chronic Obstructive Pulmonary Disease (COPD) Evidentiary Framework
Influenza and Pneumococcal Vaccinations for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Smoking Cessation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Community-Based Multidisciplinary Care for Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Pulmonary Rehabilitation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Long-term Oxygen Therapy for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Noninvasive Positive Pressure Ventilation for Acute Respiratory Failure Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Noninvasive Positive Pressure Ventilation for Chronic Respiratory Failure Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Hospital-at-Home Programs for Patients With Acute Exacerbations of Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Home Telehealth for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis
Cost-Effectiveness of Interventions for Chronic Obstructive Pulmonary Disease Using an Ontario Policy Model
Experiences of Living and Dying With COPD: A Systematic Review and Synthesis of the Qualitative Empirical Literature
For more information on the qualitative review, please contact Mita Giacomini at: http://fhs.mcmaster.ca/ceb/faculty_member_giacomini.htm.
For more information on the economic analysis, please visit the PATH website: http://www.path-hta.ca/About-Us/Contact-Us.aspx.
The Toronto Health Economics and Technology Assessment (THETA) collaborative has produced an associated report on patient preference for mechanical ventilation. For more information, please visit the THETA website: http://theta.utoronto.ca/static/contact.
Objective
The objective of this health technology assessment was to determine the effectiveness and cost-effectiveness of noninvasive ventilation for stable chronic obstructive pulmonary disease (COPD).
Clinical Need: Condition and Target Population
Noninvasive ventilation is used for COPD patients with chronic respiratory failure. Chronic respiratory failure in COPD patients may be due to the inability of the pulmonary system to coordinate ventilation, leading to adverse arterial levels of oxygen and carbon dioxide. Noninvasive ventilation in stable COPD patients has the potential to improve quality of life, prolong survival, and improve gas exchange and sleep quality in patients who are symptomatic after optimal therapy, have hypercapnia or nocturnal hypoventilation and mild hypercapnia, and are frequently hospitalized.
Technology
Noninvasive positive pressure ventilation (NPPV) is any form of positive ventilatory support without the use of an endotracheal tube. For stable COPD, the standard of care when using noninvasive ventilation is bilevel positive airway pressure (BiPAP). Bilevel positive airway pressure involves both inspiratory and expiratory pressure, high during inspiration and lower during expiration. It acts as a pressure support to accentuate a patient’s inspiratory efforts. The gradient between pressures maintains alveolar ventilation and helps to reduce carbon dioxide levels. Outpatients typically use BiPAP at night. Additional advantages of using BiPAP include resting of respiratory muscles, decreased work of breathing, and control of obstructive hypopnea.
Research Question
What is the effectiveness and cost-effectiveness of noninvasive ventilation, compared with no ventilation while receiving usual care, for stable COPD patients?
Research Methods
Literature Search
Search Strategy
A literature search was performed on December 3, 2010, using OVID MEDLINE, OVID MEDLINE In-Process and Other Non-Indexed Citations, OVID EMBASE, EBSCO Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Wiley Cochrane Library, and the Centre for Reviews and Dissemination database for studies published from January 1, 2004 to December 3, 2010. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. When the reviewer was unsure of the eligibility of articles, a second clinical epidemiologist and then a group of epidemiologists reviewed these until consensus was reached.
Inclusion Criteria
full-text English language articles,
studies published between January 1, 2004 and December 3, 2010,
journal articles that report on the effectiveness or cost-effectiveness of noninvasive ventilation,
clearly described study design and methods, and
health technology assessments, systematic reviews, meta-analyses, randomized controlled trials (RCTs).
Exclusion Criteria
non-English papers
animal or in vitro studies
case reports, case series, or case-case studies
cross-over RCTs
studies on noninvasive negative pressure ventilation (e.g., iron lung)
studies that combine ventilation therapy with other regimens (e.g., daytime NPPV plus exercise or pulmonary rehabilitation)
studies on heliox with NPPV
studies on pulmonary rehabilitation with NPPV
Outcomes of Interest
mortality/survival
hospitalizations/readmissions
length of stay in hospital
forced expiratory volume
arterial partial pressure of oxygen
arterial partial pressure of carbon dioxide
dyspnea
exercise tolerance
health-related quality of life
Note: arterial pressure of oxygen and carbon dioxide are surrogate outcomes.
Statistical Methods
A meta-analysis and an analysis of individual studies were performed using Review Manager Version 5. For continuous data, a mean difference was calculated, and for dichotomous data, a relative risk ratio was calculated for RCTs. For continuous variables with mean baseline and mean follow-up data, a change value was calculated as the difference between the 2 mean values.
Quality of Evidence
The quality of each included study was assessed taking into consideration allocation concealment, randomization, blinding, power/sample size, withdrawals/dropouts, and intention-to-treat analyses.
The quality of the body of evidence was assessed as high, moderate, low, or very low according to the GRADE Working Group criteria. The following definitions of quality were used in grading the quality of the evidence:
Summary of Findings
Conclusions
The following conclusions refer to stable, severe COPD patients receiving usual care.
Short-Term Studies
Based on low quality of evidence, there is a beneficial effect of NPPV compared with no ventilation on oxygen gas exchange, carbon dioxide gas exchange, and exercise tolerance measured using the 6 Minute Walking Test.
Based on very low quality of evidence, there is no effect of NPPV therapy on lung function measured as forced expiratory volume in 1 second (Type II error not excluded).
Long-Term Studies
Based on moderate quality of evidence, there is no effect of NPPV therapy for the outcomes of mortality, lung function measured as forced expiratory volume in 1 second, and exercise tolerance measured using the 6 Minute Walking Test.
Based on low quality of evidence, there is no effect of NPPV therapy for the outcomes of oxygen gas exchange and carbon dioxide gas exchange (Type II error not excluded).
Qualitative Assessment
Based on low quality of evidence, there is a beneficial effect of NPPV compared with no ventilation for dyspnea based on reduced Borg score or Medical Research Council dyspnea score.
Based on moderate quality of evidence, there is no effect of NPPV therapy for hospitalizations.
Health-related quality of life could not be evaluated.
PMCID: PMC3384378  PMID: 23074437
11.  Carbon dioxide kinetics and capnography during critical care 
Critical Care  2000;4(4):207-215.
Greater understanding of the pathophysiology of carbon dioxide kinetics during steady and nonsteady state should improve, we believe, clinical care during intensive care treatment. Capnography and the measurement of end-tidal partial pressure of carbon dioxide (PETCO2) will gradually be augmented by relatively new measurement methodology, including the volume of carbon dioxide exhaled per breath (VCO2,br) and average alveolar expired PCO2 (PA̅E̅CO2). Future directions include the study of oxygen kinetics.
doi:10.1186/cc696
PMCID: PMC150038  PMID: 11094503
airway; capnography; carbon dioxide; carbon dioxide kinetics; expirogram; nonsteady state; ventilation
12.  The utility of cardiac sonography and capnography in predicting outcome in cardiac arrest 
Emergency physicians and intensivists are increasingly utilizing capnography and bedside echocardiography during medical resuscitations. These techniques have shown promise in predicting outcomes in cardiac arrest, and no cases of return of spontaneous circulation in the setting of sonographic cardiac standstill and low end-tidal carbon dioxide have been reported. This case report illustrates an example of such an occurrence. Our aims are to report a case of return of spontaneous circulation in a patient with sonographic cardiac standstill, electrocardiographic pulseless electrical activity, and low end-tidal carbon dioxide tensions and to place the case in the context of previous literature on this topic. Case report and brief review of the literature. In 254 cases reported, no patient has survived in the setting of sonographic cardiac standstill and low end-tidal carbon dioxide tension, making the reported case unique. This case should serve to illustrate the utility and limitations of combined cardiac sonography and end-tidal carbon dioxide measurement in determining prognosis during cardiac arrest.
doi:10.1007/s12245-008-0040-4
PMCID: PMC2657288  PMID: 19384520
Advanced cardiac life support; Echocardiography; Capnography; Case reports
13.  Correlation of the End-Tidal PCO2 during Laparoscopic Surgery with the pH of the Gastric Juice 
Background and Objectives:
During laparoscopy, the increase of the carbon dioxide tension may increase the synthesis of hydrochloric acid in the parietal cells of the stomach; the source of the secreted hydrogen ions is carbonic acid derived from the hydration of carbon dioxide. The present report tests this hypothesis by correlating the changes of end-tidal PCO2 (ETCO2) with the pH of the gastric juice in patients undergoing laparoscopic cholecystectomy.
Methods:
40 adult patients were investigated: 20 controls, and 20 patients receiving 100 mg nizatidine intravenously, prior to surgery. In both groups, the ETCO2 was measured by capnography and the pH of the gastric juice was monitored before carbon dioxide insufflation and at the end of laparoscopy prior to carbon dioxide deflation.
Results:
In the control group, the ETCO2 increased following carbon dioxide insufflation from a mean basal value of 30.2 (standard deviation [SD] 4.6) mm Hg to 41.1 (SD 9.5) mm Hg, while the mean pH of the gastric juice decreased significantly from 1.9 (SD 0.4) to 1.27 (SD 0.43). There was a significant negative correlation between the ETCO2 and pH of the gastric juice (r=-0.4). In the Nizatidine group, the ETCO2 also increased following carbon dioxide insufflation from a mean basal value of 30.9 (SD 3.0) mm Hg to 39.4 (SD 5.3) mm Hg. However, in contrast with the control group, the mean pH of the gastric juice did not decrease, but paradoxically increased from 1.68 (SD 0.36) to 3.6 (SD 1.02).
Conclusions:
During laparoscopy, the pH of the gastric juice is significantly decreased. This decrease is inversely related to the increase of ETCO2. The preoperative administration of the selective H2-blocker nizatidine can prevent the increase in gastric acidity and can result in a paradoxical increase of pH of the gastric juice.
PMCID: PMC3015290  PMID: 9876731
Laparoscopy; Cholecystectomy; Carbon dioxide; Capnography; H2-blocker; Nizatidine; Gastric juice; HC1
14.  Accuracy of pulse oximetry and capnography in healthy and compromised horses during spontaneous and controlled ventilation 
The objective of this prospective clinical study was to evaluate the accuracy of pulse oximetry and capnography in healthy and compromised horses during general anesthesia with spontaneous and controlled ventilation. Horses anesthetized in a dorsal recumbency position for arthroscopy (n = 20) or colic surgery (n = 16) were instrumented with an earlobe probe from the pulse oximeter positioned on the tip of the tongue and a sample line inserted at the Y-piece for capnography. The horses were allowed to breathe spontaneously (SV) for the first 20 min after induction, and thereafter ventilation was controlled (IPPV). Arterial blood, for blood gas analysis, was drawn 20 min after induction and 20 min after IPPV was started. Relationships between oxygen saturation as determined by pulse oximetry (SpO2), arterial oxygen saturation (SaO2), arterial carbon dioxide partial pressure (PaCO2), and end tidal carbon dioxide (P(et)CO2), several physiological variables, and the accuracy of pulse oximetry and capnography, were evaluated by Bland–Altman or regression analysis. In the present study, both SpO2 and P(et)CO2 provided a relatively poor indication of SaO2 and PaCO2, respectively, in both healthy and compromised horses, especially during SV. A difference in heart rate obtained by pulse oximetry, ECG, or palpation is significantly correlated with any pulse oximeter inaccuracy. If blood gas analysis is not available, ventilation to P(et)CO2 of 35 to 45 mmHg should maintain the PaCO2 within a normal range. However, especially in compromised horses, it should never substitute blood gas analysis.
PMCID: PMC227048  PMID: 12889721
15.  A Randomized Controlled Trial of Capnography in the Correction of Simulated Endotracheal Tube Dislodgement 
Objectives
Unrecognized dislodgement of an endotracheal tube (ETT) during the transport of an intubated patient can have life-threatening consequences. Standard methods to monitor these patients, such as pulse oximetry and physical examination, are both subject to inaccuracies with patient movement and ambient noise. Capnography provides a continuous and objective measure of ventilation that can alert a provider immediately to an airway problem. The objective of this study was to determine through simulation if capnography decreases time to correction of dislodged ETTs during the transport of intubated patients, in comparison to standard monitoring.
Methods
Paramedics and paramedic students were randomized as to whether or not they had capnography available to them in addition to standard monitoring during a simulated scenario. In the scenario, subjects monitored an intubated baby who subsequently experiences a dislodgement of the ETT during interfacility transport. Time to correction of the ETT dislodgement was the primary outcome. The secondary outcome was correction of dislodgement prior to decline in pulse oximetry.
Results
Fifty-three subjects were enrolled in the study, with complete data on 50 subjects. Median time to correction of ETT dislodgement was 2.02 minutes (95% CI = 1.22 to 4.12 minutes) for the capnography group versus 4.00 minutes (95% CI = 3.35 to 5.50 minutes) in the standard monitoring group (p = 0.05). Forty-eight percent of subjects using capnography corrected the ETT dislodgement prior to decline in pulse oximetry compared with 12% of controls (p = 0.01). There were no differences in time to correction of dislodgement based on years of experience, perceived comfort, reported adequacy of teaching, or past use of capnography.
Conclusions
The addition of capnography to standard monitoring significantly improves recognition of ETT dislodgement and reduces the time to correction of dislodged ETTs by prehospital providers in a simulated pediatric transport setting.
doi:10.1111/j.1553-2712.2011.01090.x
PMCID: PMC3117244  PMID: 21676056
16.  A new device for 100 per cent humidification of inspired air 
Critical Care  2000;4(1):54-60.
A new humidifier for use during mechanical ventilation in endotracheally intubated patients is described and tested. The humidifier is based on a heat-moisture exchanger, which absorbs the expired heat and moisture and releases it into the inspired air. External heat and water are then added at the patient side of the heat-moisture exchanger, so that the inspired gas should reach 100% humidity (44 mg/l) at 37°C. In bench tests using constant and decelerating inspiratory flow and minute volumes of 3–25 l the device gave an absolute humidity of 41–44 mg/l, and it reduced the amount of water consumed in eight mechanically ventilated patients compared with a conventional active humidifier. During a 24-h test period there was no water condensation in the ventilator tubing with the new device.
Introduction:
Devices for active humidification of the inspired air in mechanically ventilated patients cause water condensation in the ventilator tubing, which may become contaminated or interfere with the function of the ventilator. The present study describes and tests the performance of a new humidifier, which is designed to eliminate water condensation.
Objectives:
To test the performance of the new humidifier at different ventilator settings in a lung model, and to compare this new humidifier with a conventional active humidifier in ventilator-treated critically ill patients.
Materials and methods:
The humidifier (Humid-Heat; Louis Gibeck AB, Upplands Väsby, Sweden) consists of a supply unit with a microprocessor and a water pump, and a humidification device, which is placed between the Y-piece and the endotracheal tube. The humidification device is based on a hygroscopic heat-moisture exchanger (HME), which absorbs the expired heat and moisture and releases it into the inspired gas. External heat and water are then added to the patient side of the HME, so the inspired gas should reach 100% humidity at 37°C (44 mg H2O/l air). The external water is delivered to the humidification device via a pump onto a wick and then evaporated into the inspired air by an electrical heater. The microprocessor controls the water pump and the heater by an algorithm using the minute ventilation (which is fed into the microprocessor) and the airway temperature measured by a sensor mounted in the flex-tube on the patient side of the humidification device.
The performance characteristics were tested in a lung model ventilated with a constant flow (inspiratory:expiratory ratio 1:2, rate 12–20 breaths/min and a minute ventilation of 3–25 l/min) or with a decelerating flow (inspiratory:expiratory ratio 1:2, rate 12–15 breaths/min and a minute ventilation of 4.7–16.4 l/min). The device was also tested prospectively and in a randomized order compared with a conventional active humidifier (Fisher & Paykel MR730, Auckland, New Zealand) in eight mechanically ventilated, endotracheally intubated patients in the intensive care unit. The test period with each device was 24 h. The amount of fluid consumed and the amount of water in the water traps were measured. The number of times that the water traps were emptied, changes of machine filters, the suctions and quality of secretions, nebulizations, and the amount of saline instillations and endotracheal tube obstruction were recorded. In order to evaluate increased expiratory resistance due to the device, the airway pressure was measured at the end of a prolonged end-expiratory pause at 1 h of use and at the end of the test, and was compared with the corresponding pressure before the experiment. The body temperature of the patient was measured before and after the test of each device.
Results:
Both with constant flow and decelerating flow, the Humid-Heat gave an absolute humidity of 41–44 mgH2O/l at 37°C, with the lower level at the highest ventilation. In the patients, both Humid-Heat and the conventional active humidifier (MR730) maintained temperatures, indicating that they provided the intended heat and moisture to the inspired air. With both devices, the body temperature was maintained during the test period. There was no difference in the amount of secretions, the quality of the secretions and the frequency of suctions, saline instillations or nebulizations between the test periods with the two devices. There was no endotracheal tube obstruction, and after 1 h of use and at the end of the test no increased airway resistance was found with either device. When the MR730 was used, however, the water traps needed to be emptied six to 14 (mean eight) times (total amount of fluid in the traps was 100–300 ml) and the machine filters were changed two to six (mean four) times due to an excessive amount of condensed water with flow obstruction. No condensation of water was found in the tubing with the Humid-Heat. The water consumption was 23–65 ml/h (mean 30 ml/h) with the MR730 and 4–8 ml/h (mean 6 ml/h) with the Humid-Heat (P < 0.0008). The same relations were found when the water consumption was corrected for differences in minute ventilation.
Discussion:
The new humidifier, the Humid-Heat, gave an absolute humidity of 41–44 mg/l at 37°C in the bench tests. The tests in ventilated patients showed that the device was well tolerated and that condensation in the tubing was eliminated. There was no need to empty water traps. The test period was too short to evaluate whether the new device had any other advantages or disadvantages compared with conventional humidifiers.
PMCID: PMC29037  PMID: 11056746
airway humidification; heated humidifier; intensive care; mechanical ventilation
17.  Cerebral Oxygen Saturation: Graded Response to Carbon Dioxide with Isoxia and Graded Response to Oxygen with Isocapnia 
PLoS ONE  2013;8(2):e57881.
Background
Monitoring cerebral saturation is increasingly seen as an aid to management of patients in the operating room and in neurocritical care. How best to manipulate cerebral saturation is not fully known. We examined cerebral saturation with graded changes in carbon dioxide tension while isoxic and with graded changes in oxygen tension while isocapnic.
Methodology/Principal Findings
The study was approved by the Research Ethics Board of the University Health Network at the University of Toronto. Thirteen studies were undertaken in healthy adults with cerebral oximetry by near infrared spectroscopy. End-tidal gas concentrations were manipulated using a model-based prospective end-tidal targeting device. End-tidal carbon dioxide was altered ±15 mmHg from baseline in 5 mmHg increments with isoxia (clamped at 110±4 mmHg). End-tidal oxygen was changed to 300, 400, 500, 80, 60 and 50 mmHg under isocapnia (37±2 mmHg). Twelve studies were completed. The end-tidal carbon dioxide versus cerebral saturation fit a linear relationship (R2 = 0.92±0.06). The end-tidal oxygen versus cerebral saturation followed log-linear behaviour and best fit a hyperbolic relationship (R2 = 0.85±0.10). Cerebral saturation was maximized in isoxia at end-tidal carbon dioxide of baseline +15 mmHg (77±3 percent). Cerebral saturation was minimal in isocapnia at an end-tidal oxygen tension of 50 mmHg (61±3 percent). The cerebral saturation during normoxic hypocapnia was equivalent to normocapnic hypoxia of 60 mmHg.
Conclusions/Significance
Hypocapnia reduces cerebral saturation to an extent equivalent to moderate hypoxia.
doi:10.1371/journal.pone.0057881
PMCID: PMC3585256  PMID: 23469096
18.  Correlation of End-Tidal Carbon Dioxide with Arterial Carbon Dioxide in Mechanically Ventilated Patients 
Archives of Trauma Research  2012;1(2):58-62.
Background:
Patients undergone mechanical ventilation need rapid and reliable evaluation of their respiratory status. Monitoring of End-tidal carbon dioxide (ETCO2) as a surrogate, noninvasive measurement of arterial carbon dioxide (PaCO2) is one of the methods used for this purpose in intubated patients.
Objectives:
The aim of the present trial was to study the relationship between end-tidal CO2 tensions with PaCO2 measurements in mechanically ventilated patients.
Materials and Methods:
End-tidal carbon dioxide levels were recorded at the time of arterial blood gas sampling. Patients who were undergoing one of the mechanical ventilation methods such as: synchronized mandatory mechanical ventilation (SIMV), continuous positive airway pressure (CPAP) and T-Tube were enrolled in this study. The difference between ETCO2 and PaCO2 was tested with a paired t-test. The correlation of end-tidal carbon dioxide to (ETCO2) CO2 was obtained in all patients.
Results:
A total of 219 arterial blood gases were obtained from 87 patients (mean age, 71.7 ± 15.1 years). Statistical analysis demonstrated a good correlation between the mean of ETCO2 and PaCO2 in each of the modes of SIMV, CPAP and T-Tube; SIMV (42.5 ± 17.3 and 45.8 ± 17.1; r = 0.893, P < 0.0001), CPAP (37 ± 9.7 and 39.4 ± 10.1; r = 0.841, P < 0.0001) and T-Tube (36.1 ± 9.9 and 39.4 ± 11; r = 0.923, P < 0.0001), respectively.
Conclusions:
End-tidal CO2 measurement provides an accurate estimation of PaCO2 in mechanically ventilated patients. Its use may reduce the need for invasive monitoring and/or repeated arterial blood gas analyses.
doi:10.5812/atr.6444
PMCID: PMC3876523  PMID: 24396744
Blood Gas Analysis; Carbon Dioxide; Artificial Respiration
19.  A modified technique to improve the outcome of intubation with a left-sided double-lumen endobronchial tube 
BMC Anesthesiology  2014;14:72.
Background
The use of a video-assisted laryngoscope (VL) has been shown to reduce the time to achieve intubation with a double-lumen endobronchial tube (DLT). As the blade of the VL is curved differently to a standard laryngoscope, the DLT must be angled into a hockey stick shape to fit properly. We conducted a study to establish which direction of angulation was best to facilitate correct positioning of the DLT when using a VL.
Methods
We enrolled patients scheduled for thoracic surgery who required intubation with a DLT. They were prospectively randomized into one of two groups: those intubated with a DLT angled to conceal the tracheal orifice (the tracheal orifice-covered, TOC) group or the tracheal orifice-exposed (TOE) group. The composite primary outcome measures were time taken to intubate and the frequency of first-time success. The time taken to intubate was divided into: T1, the time from mouth opening to visualization of the vocal cords with the VL; and T2, the time taken to advance the DLT through the cords until its tip lay within the trachea and three carbon dioxide waveforms had been detected by capnography. The hemodynamic responses to intubation and intubation-related adverse events were also recorded.
Results
Sixty-six patients completed the study, with 33 in each group. Total intubation time was significantly shorter in the TOC group (mean 30.6 ± standard deviation 2.7 seconds versus 38.7 ± 3.3 seconds, p <0.0001). T2 was also significantly shorter in the TOC group than the TOE group (27.2 ± 2.5 seconds versus 34.9 ± 3.0 seconds, p <0.0001). The severity of hoarseness on the first postoperative day and sore throat on the fourth postoperative day were significantly lower in the TOC group than the TOE group (p = 0.02 and <0.0001, respectively). The hemodynamic responses to intubation were broadly similar between the groups.
Conclusion
When placing a left-sided DLT using a VL, angling the bronchial lumen to a hockey stick shape that conceals the tracheal lumen saves time and ameliorates the severity of post-intubation complications.
Trial registration
ClinicalTrials.gov Identifier: NCT01605591.
doi:10.1186/1471-2253-14-72
PMCID: PMC4158352  PMID: 25206313
Left-sided double-lumen endobronchial tube; Video-assisted Laryngoscope; Angling
20.  Influence of Head Flexion After Endotracheal Intubation on Intraocular Pressure and Cardio-Respiratory Response in Patients Undergoing Cataract Surgery 
Ghana Medical Journal  2008;42(3):105-109.
Background
During preparation and draping of periorbital area, neck flexion causes displacement of the endotracheal tube tip toward the carina. Stimulation of the tracheal mucosa may cause bucking, increased intraocular pressure (IOP), laryngospasm, bronchospasm, change in end-tidal carbon dioxide pressure (PETCO2) or peripheral arterial haemoglobin oxygen saturation (SpaO2) during light anaesthesia.
Objective
To investigate the influence of head and neck flexion after endotracheal intubation on heart rate (HR), systolic and diastolic blood pressure (SAP and DAP), SpaO2, PETCO2 and IOP in patients undergoing cataract surgery during general anesthesia.
Method
In this prospective observational study, 106 ASA physical status I and II patients scheduled for elective cataract surgery under general anaesthesia were studied. Anaesthesia was induced with thiopental sodium, lidocaine and fentanyl. Atracurium 0.5 mg/kg was given to facilitate tracheal intubation. HR, SAP, DAP, SpaO2, PETCO2, and IOP were measured at 1, 2, and 5 minutes after head flexion.
Results
Mean SAP, DAP, IOP, and HR were significantly increased after head flexion compared with baseline values (P < 0.05). PETCO2 and SpaO2 were significantly decreased at 1 and 2 minutes after head flexion compared with baseline values (P < 0.001).
Conclusion
It is concluded that endotracheal tube movement by changes in head and neck position has significant effects on heart rate, systolic and diastolic blood pressures, laryngeal reflexes, SpaO2, PETCO2, and intraocular pressure in patients undergoing cataract surgery under general anaesthesia.
PMCID: PMC2643427  PMID: 19274108
endotracheal intubation; intraocular pressure; head and neck positioning; pressor responses; respiratory responses
21.  Carbon dioxide monitoring and evidence-based practice – now you see it, now you don't 
Critical Care  2004;8(4):219-221.
Carbon dioxide has been monitored in the body using a variety of technologies with a multitude of applications. The monitoring of this common physiologic variable in medicine is an illustrative example of the different levels of evidence that are required before any new health technology should establish itself in clinical practice. End-tidal capnography and sublingual capnometry are two examples of carbon dioxide monitoring that require very different levels of evidence before being disseminated widely. The former deserves its status as a basic standard based on observational data. The latter should be considered investigational until prospective controlled data supporting its use become available. Other applications of carbon dioxide monitoring are also discussed.
doi:10.1186/cc2916
PMCID: PMC522858  PMID: 15312200
biomedical technology assessment; capnography; critical care; evidence-based medicine; physiologic monitoring
22.  Early diagnosis of airway closure from pigtail signature capnogram and its management in intubated small infants undergoing general anaesthesia for surgery 
Indian Journal of Anaesthesia  2010;54(4):331-334.
Spontaneous glottis closure during expiration in infants is a normal protective reflex that helps prevent alveolar and small airway collapse (due to compliant chest wall) and thereby maintains functional residual capacity. Endotracheal intubation eliminates this protective mechanism and puts the infant into the risk of hypoxaemia and hypercarbia. This report sums up the early detection of airway closure in a series of three intubated small infants undergoing surgery with general anaesthesia, by the appearance of typical pigtail shaped capnogram, associated with decreased end tidal carbon dioxide and mild hypoxaemia, which was successfully managed by early institution of positive end expiratory pressure.
doi:10.4103/0019-5049.68379
PMCID: PMC2943704  PMID: 20882177
Airway closure; continuous positive airway pressure end tidal carbon dioxide; glottic closure; positive end expiratory pressure; pigtail capnogram; hypercarbia; hypoxaemia
23.  The use of capnometry to predict arterial partial pressure of CO2 in non-intubated breathless patients in the emergency department 
Background
Capnometry measures carbon dioxide in expired air and provides the clinician with a noninvasive measure of the systemic metabolism, circulation and ventilation. This study was carried out on patients with acute breathlessness to define the utility and role of capnometry in the emergency department.
Aim
The objectives of the study were: To determine the correlation between end tidal CO2 and PaCO2 in non-intubated acutely breathless patients.To determine factors that influence the end tidal carbon dioxide (ETCO2).To determine the correlation between ETCO2 with PaCO2 in patients presenting with pulmonary disorders.
Methods
One hundred fifty acutely breathless patients arriving at the emergency department and fulfilling the inclusion and exclusion criteria were chosen during a 6-month study period. The patients gave written or verbal consent, and were triaged and treated according to their presenting complaints. Demographic data were collected, and the ETCO2 data were recorded. Arterial blood gas was taken in all patients. The data were compiled and analyzed using various descriptive studies from the Statistics Program for Social Studies (SPSS) version 12. Correlation between ETCO2 and PaCO2 was analyzed using the Pearson correlation coefficient. Other variables also were analyzed to determine the correlation using simple linear regression. The agreement and difference between ETCO2 and PaCO2 were analyzed using paired sample t-tests.
Results
There is a strong correlation between ETCO2 and PaCO2 using the Pearson correlation coefficient: 0.716 and p value of 0.00 (p < 0.05). However, the paired t-test showed a mean difference between the two parameters of 4.303 with a p value < 0.05 (95% CI 2.818, 5.878). There was also a good correlation between ETCO2 and acidosis state with a Pearson correlation coefficient of 0.374 and p value 0.02 (p < 0.05). A strong correlation was also observed between ETCO2 and a hypocapnic state, with a Pearson correlation coefficient of 0.738 (p < 0.05). Weak correlation was observed between alkalosis and ETCO2, with a Pearson correlation coefficient of 0.171 (p < 0.05). A strong negative correlation was present between ETCO2 and hypercapnic patients presenting with pulmonary disorders, with a Pearson correlation coefficient of -0.738 (p < 0.05) and of -0.336 (p < 0.05), respectively.
Conclusion
This study shows that ETCO2 can be used to predict the PaCO2 level when the difference between the PaCO2 and ETCO2 is between 2 to 6 mmHg, especially in cases of pure acidosis and hypocapnia. Using ETCO2 to predict PaCO2 should be done with caution, especially in cases that involve pulmonary disorders and acid-base imbalance.
doi:10.1007/s12245-010-0233-5
PMCID: PMC3047830  PMID: 21373299
Capnometry; End tidal; Dyspnea; Blood gas
24.  Fiber optic bronchoscopy in patients with acute hypoxemic respiratory failure requiring noninvasive ventilation - a feasibility study 
Critical Care  2011;15(4):R179.
Introduction
Noninvasive ventilation (NIV) is a standard procedure in selected patients with acute respiratory failure. Previous studies have used noninvasive ventilation to ensure adequate gas exchange during fiberoptic bronchoscopy in spontaneously breathing hypoxemic patients, thus avoiding endotracheal intubation. However, it is unknown whether bronchoscopy can be performed safely in patients with acute hypoxemic respiratory failure already in need of NIV prior to the decision for bronchoscopy.
Methods
We prospectively investigated 40 consecutive, critically ill, adult patients with acute hypoxemic respiratory failure (14 women, 26 men, age 61 ± 15 years, partial pressure for oxygen/fraction of inspired oxygen (PaO2/FiO2) < 300 under noninvasive ventilation, Simplified Acute Physiology scores (SAPS II) 47 ± 9.9 points). All patients required noninvasive ventilation prior to the decision to perform bronchoscopy (median 10.5 h; range 2.2 to 114). Blood gases, heart rate, blood pressure and ventilation were monitored before, during and up to 120 minutes after bronchoscopy.
Results
Bronchoscopy could be completed in all patients without subsequent complications. Oxygen saturation fell to < 90% in two patients (5%), and the lowest value during the procedure was 84%. The mean PaO2/FiO2 ratio improved from 176 ± 54 at baseline to 240 ± 130 (P < 0.001) at the end of bronchoscopy and 210 ± 79 after 120 minutes. The transient mean partial pressure of carbon dioxide in the arterial blood (PaCO2) increase was 9.4 ± 8.1 mm Hg. Four patients (10%) required endotracheal intubation during the first eight hours after the procedure. Bronchoalveolar lavage yielded diagnostic information in 26 of 38 (68%) patients.
Conclusions
In critically ill patients with acute hypoxemic respiratory failure requiring noninvasive ventilation, bronchoscopy can be performed with an acceptable risk. Since these patients per se have a high likelihood of subsequent endotracheal intubation due to failure of NIV, bronchoscopy should only be performed by experienced clinicians.
doi:10.1186/cc10328
PMCID: PMC3387622  PMID: 21794138
25.  Video Laryngoscopy for Tracheal Intubation 
Executive Summary
Objective
The objective of this health technology policy assessment was to determine the effectiveness and cost-effectiveness of video-assisted laryngoscopy for tracheal intubation.
The Technology
Video-assisted, rigid laryngoscopes have been recently introduced that allow for the illumination of the airway and the accurate placement of the endotracheal tube. Two such devices are available in Canada: the Bullard® Laryngoscope that relies on fibre optics for illumination and the GlideScope® that uses a video camera and a light source to illuminate the airway. Both are connected to an external monitor so health professionals other than the operator can visualize the insertion of the tube. These devices therefore may be very useful as teaching aids for tracheal intubation.
Review Strategy
The objective of this review was to examine the effectiveness of the most commonly used video-assisted rigid laryngoscopes used in Canada for tracheal intubation. According to the Medical Advisory Secretariat standard search strategy, a literature search for current health technology assessments and peer-reviewed literature from Medline (full citations, in-process and non-indexed citations) and Embase for was conducted for citations from January 1994 to January 2004. Key words used in the search were as follows: Video-assisted; video; emergency; airway management; tracheal intubation and laryngoscopy.
Summary of Findings
Two video-assisted systems are available for use in Canada. The Bullard® video laryngscope has a large body of literature associated with it and has been used for the last 10 years, although most of the studies are small and not well conducted. The literature on the GlideScope® is limited. In general, these devices provide better views of the airway but are much more expensive than conventional direct laryngoscopes. As with most medical procedures, video-assisted laryngoscopy requires training and skill maintenance for successful use.
There seems to be a discrepancy between the seeming advantages of these devices in the management of difficult airway and their availability and uptake outside the operating room. The uptake of these devices by non-anesthetists in Ontario at this time may be limited because:
Difficult intubation is relatively infrequent outside the operating room
Many alternative and inexpensive devices are available
There are no professional supports in place for the training and maintenance of skills for the use of these devices outside anesthesia.
Video laryngoscopy has no obvious utility in preventing airborne viral transmission from patient to provider but may be useful for teaching purposes.
PMCID: PMC3387773  PMID: 23074455

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