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.
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.
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.
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.
Objectives—The purpose of this study was to determine effects of different airway devices and tidal volumes on lung ventilation and gastric inflation in an unprotected airway.
Methods—Thirty one non-anaesthesia house officers volunteered for the study, and ventilated a bench model simulating an unintubated respiratory arrest patient with bag-valve-facemask, laryngeal mask airway, and combitube using paediatric and adult self inflating bags.
Results—The paediatric versus adult self inflating bag resulted with the laryngeal mask airway and combitube in significantly (p<0.001) lower mean (SEM) lung tidal volumes (376 (30) v 653 (47) ml, and 368 (28) v 727 (53) ml, respectively). Gastric inflation was zero with the combitube; and 0 (0) v 8 (3) ml with the laryngeal mask airway with low versus large tidal volumes. The paediatric versus adult self inflating bag with the bag-valve-facemask resulted in comparable lung tidal volumes (245 (19) v 271 (33) ml; p=NS); but significantly (p<0.001) lower gastric tidal volume (149 (11) v 272 (24) ml).
Conclusions—The paediatric self inflating bag may be an option to reduce the risk of gastric inflation when using the laryngeal mask airway, and especially, the bag-valve-facemask. Both the laryngeal mask airway and combitube proved to be valid alternatives for the bag-valve-facemask in this experimental model.
Aims to compare the efficacy of Proseal laryngeal mask airway(PLMA) and endotracheal tube (ETT) in patients undergoing laparoscopic surgeries under general anaesthesia. This prospective randomised study was conducted on 60 adult patients, 30 each in two groups, of ASA I-II who were posted for laparoscopic procedures under general anaesthesia. After preoxygenation, anaesthesia was induced with propofol, fentanyl and vecuronium. PLMA or ETT was inserted and cuff inflated. Nasogastric tube (NGT) was passed in all patients. Anaesthesia was maintained with N2 O, O2, halothane and vecuronium. Ventilation was set at 8 ml/kg and respiratory rate of 12/min. The attempts and time taken for insertion of devices, haemodynamic changes, oxygenation, ventilation and intraoperative and postoperative laryngopharyngeal morbidity (LPM) were noted. There was no failed insertion of devices. Time taken for successful passage of NGT was 9.77 s (6-16 s) and 11.5 s (8-17 s) for groups P and E, respectively. There were no statistically significant differences in oxygen saturation (SpO2) or end-tidal carbon dioxide (EtCO2) between the two groups before or during peritoneal insufflation. Median (range) airway pressure at which oropharyngeal leak occurred during the leak test with PLMA was 35 (24-40) cm of H2O. There was no case of inadequate ventilation, regurgitation, or aspiration recorded. No significant difference in laryngopharyngeal morbidity was noted. A properly positionedPLMA proved to be a suitable and safe alternative to ETT for airway management in elective fasted, adult patients undergoing laparoscopic surgeries. It provided equally effective pulmonary ventilation despite high airway pressures without gastric distention, regurgitation, and aspiration.
Endotracheal tube; IPPV; laparoscopy; oropharyngeal seal pressure; Proseal LMA
Preoxygenation with tidal volume breathing for 3 min is commonly used technique. An end tidal expiratory oxygen concentration greater than 90% is considerd to be adequate for preoxygenation. The aim of this study was to check the effects of preoxygenation on elderly patients through the comparison with young patients during the 3 min tidal volume breathing technique.
Sixty patients from ASA class I or II who were scheduled for elective orthopedic general surgery were divided into an elderly (>65 yr) group and a control (25-65 yr) group. Patients were instructed in the technique of preoxygenation. Preoxygenation was accomplished with an appropriately sized face mask connected to an anesthesia machine with 100% oxygen during 3 min with patients in both groups. Expired O2, CO2 concentration and oxygen saturation were recorded simultaneously for 3 min.
The elderly group showed significantly lower end tidal oxygen concentration than the control group from 50 sec to the end of study (180 sec) with the 3 min tidal volume breathing technique (P < 0.05). In 180 sec, the control group had over 90% (91.5%) end tidal oxygen concentration, but in the elderly group end tidal oxygen concentration could not reach 90% (86.2%). In oxygen saturation, the elderly group showed a significantly lower level until 40 sec from the start of study, and then two groups showed a similar levels of oxygen saturation until the end of study.
End tidal oxygen concentration did not reach 90% in 180 sec in the elderly group during preoxygenation with the 3 min tidal volume breathing technique.
Elderly; Mask; Oxygen concentration; Preoxygenation; 3 min tidal volume breathing
To compare repeatability and agreement of conventional ultrasound bladder wall thickness (BWT) measurements with automatically obtained BWT measurements by the BVM 6500 device.
Adult patients with lower urinary tract symptoms, urinary incontinence, or postvoid residual urine were urodynamically assessed. During two subsequent cystometry sessions the infusion pump was temporarily stopped at 150 and 250 ml bladder filling to measure BWT with conventional ultrasound and the BVM 6500 device. For each method and each bladder filling, repeatability and variation was assessed by the method of Bland and Altman.
Fifty unselected patients (30 men, 20 women) aged 21–86 years (median 62.5 years) were prospectively evaluated. Invalid BWT measurements were encountered in 2.1–14% of patients when using the BVM 6500 versus 0% with conventional ultrasound (significant only during the second measurement at 150 ml bladder filling). Mean difference in BWT values between the measurements of one technique was −0.1 to +0.01 mm. Measurement variation between replicate measurements was smaller for conventional ultrasound and the smallest for 250 ml bladder filling. Mean difference between the two techniques was 0.11–0.23 mm and did not differ significantly. The BVM 6500 device was not able to correctly measure BWTs above 4 mm.
Both BWT measurements are repeatable and agree with each other. However, conventional ultrasound measurements have a smaller measurement variance, can measure BWT in all patients, and BWTs above 4 mm.
Bladder wall thickness; Ultrasound; BVM 6500; Repeatability; Accuracy
Managing an airway in an unconscious athlete is a lifesaving skill that may be made more difficult by the recent changes in protective equipment. Different airway maneuvers and techniques may be required to help ventilate an unconscious athlete who is wearing full protective equipment.
To assess the effectiveness of different airway maneuvers with football, ice hockey, and soccer players wearing full protective equipment.
University sports medicine clinic.
Patients or Other Participants:
A total of 146 university varsity athletes, consisting of 62 football, 45 ice hockey, and 39 soccer players.
Athletes were assessed for different airway and physical characteristics. Three investigators then evaluated the effectiveness of different bag-valve-mask (BVM) ventilation techniques in supine athletes who were wearing protective equipment while inline cervical spine immobilization was maintained.
Main Outcome Measure(s):
The effectiveness of 1-person BVM ventilation (1-BVM), 2-person BVM ventilation (2-BVM), and inline immobilization and ventilation (IIV) was judged by each investigator for each athlete using a 4-point rating scale.
All forms of ventilation were least difficult in soccer players and most difficult in football players. When compared with 1-BVM, both 2-BVM and IIV were deemed more effective by all investigators for all athletes. Interference from the helmet and stabilizer were common reasons for difficult ventilation in football and ice hockey players.
Sports medicine professionals should practice and be comfortable with different ventilation techniques for athletes wearing full equipment. The use of a new ventilation technique, termed inline immobilization and ventilation, may be beneficial, especially when the number of responders is limited.
emergency management; ventilation; resuscitation
We reported similar rates of ventilator-associated pneumonia (VAP) previously in trauma patients intubated either in a pre-hospital (PH) venue or the emergency department. A subset of PH intubations with continuous quality assessment was re-examined to identify the intubation factors associated with VAP.
The subgroup was derived from an existing data set of consecutive adult trauma patients intubated prior to Level I trauma center admission July 2007–July 2008. Intubation details recorded included bag-valve mask ventilation (BVM) and the presence of material in the airway. The diagnosis of VAP was made preferentially by quantitative bronchoalveolar lavage (BAL) cultures (≥104 colony-forming units indicating infection). Baseline data, injury characteristics, and circumstances of intubation of patients with and without VAP were compared by univariable analysis.
Detailed data were available for 197 patients; 32 (16.2%) developed VAP, on average 6.0±0.7 days after admission. Baseline characteristics were similar in the groups, but diabetes mellitus was more common in the VAP group (4 [12.5%] vs. 5 [3.0%]; p=0.02). There was a higher rate of blunt injury in the VAP patients (28 [87.5%] vs. 106 [64.2%]; p=0.01) and higher injury severity scores (33.1±2.8 vs. 23.0±1.0; p=0.0002) and chest Abbreviated Injury Scores (2.6±0.3 vs. 1.5±0.1; p=0.002). Lower Glasgow Coma Scale scores (7.9±0.9 vs. 9.9±0.4; p=0.04) and greater use of BVM (18 [56.3%] vs. 56 [34.0%]; p=0.02) were observed in patients who developed VAP. Among aspirations, 10 (31.3%) of patients with emesis developed VAP compared with only 4 (12.5%) with blood in the airway (p=0.003).
Aspiration, along with depressed consciousness and greater injury severity, may predispose trauma patients to VAP. Prospective studies should focus on the quality and timing of aspiration relative to intubation to determine if novel interventions can prevent aspiration or decrease the risk of VAP after aspiration.
Background: The key to successful neonatal resuscitation is effective ventilation. Little evidence exists to guide clinicians in their choice of manual ventilation device or face mask. The expiratory tidal volume measured at the mask (VTE(mask)) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation.
Aim: To compare the efficacy of (a) the Laerdal infant resuscitator and the Neopuff infant resuscitator, used with (b) round and anatomically shaped masks in a model of neonatal resuscitation.
Methods: Thirty four participants gave positive pressure ventilation to a mannequin at specified pressures with each of the four device-mask combinations. Flow, inspiratory tidal volume at the face mask (VTI(mask)), VTE(mask), and airway pressure were recorded. Leakage from the mask was calculated from VTI(mask) and VTE(mask).
Results: A total of 10 780 inflations were recorded and analysed. Peak inspiratory pressure targets were achieved equally with the Laerdal and Neopuff resuscitators. Positive end expiratory pressure was delivered with the Neopuff but not the Laerdal device. Despite similar peak pressures, VTE(mask) varied widely. Mask leakage was large for each combination of device and mask. There were no differences between the masks.
Conclusion: During face mask ventilation of a neonatal resuscitation mannequin, there are large leaks around the face mask. Airway pressure is a poor proxy for volume delivered during positive pressure ventilation through a mask.
Changes in arterial blood gases as a result of transporting 28 stable postoperative cardiovascular surgical patients to the intensive care unit were studied. Three methods of ventilation during the 3-minute transport period were compared. All patients were ventilated with 100% oxygen prior to transport. Nine patients were ventilated with air by a self-inflating, non-rebreathing bag. Ten patients were not ventilated at all. Nine patients were ventilated with oxygen in a closed rebreathing circuit constructed from disposable portions of the anesthesia circuit. Oxygen tension on arrival in the intensive care unit was highest in the group ventilated with the closed rebreathing circuit and lowest in the group ventilated with room air. Carbon dixoide tension rose 6.2 mm Hg/min in unventilated patients, 3.2 mm Hg/min in patients ventilated with the closed rebreathing circuit, and did not change in the group ventilated with air.
We conclude that stable patients can be safely transported while breathing air for 3 minutes. For longer periods of transport, the closed rebreathing circuit provides high oxygen tension with acceptable hypercarbia and provides a convenient alternative to the use of portable oxygen tanks.
Bevirimat (BVM; formerly known as PA-457) is a novel inhibitor of human immunodeficiency virus (HIV) maturation that is being developed for the treatment of HIV infection. The pharmacokinetics of this agent in healthy male volunteers were studied in a randomized, double-blind study in which the participants received single oral doses of placebo (n = 8) or escalating doses of BVM at 25, 50, 100, or 250 mg (n = 6 per dose); escalation was performed only after the pharmacokinetics and safety of the preceding dose had been evaluated. Plasma was collected over 480 h after dosing and urine was collected over 48 h after dosing for determination of the values of pharmacokinetic parameters. BVM was well absorbed after oral administration, with peak plasma concentrations being achieved 1 to 3 h after dosing. The half-life was 60 to 80 h. The exposure assessed by determination of the peak concentration and the area under the concentration-time curve was dose proportional. Single oral doses of BVM were well tolerated: there were no dose-limiting toxicities, and no serious adverse events were reported. These findings suggest that that BVM offers a favorable pharmacokinetic profile, with predictable pharmacokinetics following the oral administration of single doses. The long half-life of BVM may facilitate once-daily dosing.
To determine the utility of post contrast susceptibility-weighted magnetic resonance imaging (PCSWI) in the evaluation of vascular malformations of the brain (BVM).
Materials and Methods
We retrospectively evaluated PCSWI and digital subtraction angiography (DSA) data from 16 consecutive patients with known or suspected BVM, which had been entered into a prospectively maintained database during a 1-year period. There had been no intervening treatment or change in patients’ symptoms between the PCSWI and DSA studies. The utility of PCSWI in the detection of AVS was compared to that of routine non-contrast susceptibility weighted imaging (SWI), time of flight Magnetic Resonance angiography (TOFMRA) and contrast enhanced Magnetic Resonance angiography (CEMRA) using DSA results as the reference standard. The presence of AVS in PCSWI or SWI sequences was defined by the presence of abnormal signal hyperintensity in the venous structures adjacent to the BVM.
A total of 17 BVMs were identified by DSA (9 newly diagnosed arteriovenous malformations, 3 dural arteriovenous fistulas, 4 treated arteriovenous malformations with residual AVS and 1 complex developmental venous anomaly). PCSWI was 100% sensitive and 100% specific with 100% positive predictive value (PPV) and 100% negative predictive value (NPV) for the detection of AVS in these BVMs. The PCSWI/SWI signal intensity ratio in the most prominent early draining venous structure was 1.2 ± 0.32.
PCSWI appears to be superior to SWI, TOFMRA and CEMRA in detecting AVS in BVMs and may be useful in the initial diagnosis and follow-up of patients with BVMs.
Susceptibility-weighted imaging (SWI); Arteriovenous shunting; Arteriovenous malformation (AVM); Developmental venous anomalies (DVA)
In 1999, the laryngeal tube (VBM Medizintechnik, Sulz, Germany) was introduced as a new supraglottic airway. It was designed to allow either spontaneous breathing or controlled ventilation during anaesthesia; additionally it may serve as an alternative to endotracheal intubation, or bag-mask ventilation during resuscitation. Several variations of this supraglottic airway exist. In our study, we compared ventilation with the laryngeal tube suction for single use (LTS-D) and a bag-mask device. One of the main points of the revised ERC 2005 guidelines is a low no-flow-time (NFT). The NFT is defined as the time during which no chest compression occurs. Traditionally during the first few minutes of resuscitation NFT is very high. We evaluated the hypothesis that utilization of the LTS-D could reduce the NFT compared to bag-mask ventilation (BMV) during simulated cardiac arrest in a single rescuer manikin study.
Participants were studied during a one day advanced life support (ALS) course. Two scenarios of arrhythmias requiring defibrillation were simulated in a manikin. One scenario required subjects to establish the airway with a LTS-D; alternatively, the second scenario required them to use BMV. The scenario duration was 430 seconds for the LTS-D scenario, and 420 seconds for the BMV scenario, respectively. Experienced ICU nurses were recruited as study subjects. Participants were randomly assigned to one of the two groups first (LTS-D and BMV) to establish the airway. Endpoints were the total NFT during the scenario, the successful airway management using the respective device, and participants' preference of one of the two strategies for airway management.
Utilization of the LTS-D reduced NFT significantly (p < 0.01). Adherence to the time frame of ERC guidelines was 96% in the LTS-D group versus 30% in the BMV group. Two participants in the LTS-D group required more than one attempt to establish the LTS-D correctly. Once established, ventilation was effective in 100%. In a subjective evaluation all participants preferred the LTS-D over BMV to provide ventilation in a cardiac arrest scenario.
In our manikin study, NFT was reduced significantly when using LTS-D compared to BMV. During cardiac arrest, the LTS-D might be a good alternative to BMV for providing and maintaining a patent airway. For personnel not experienced in endotracheal intubation it seems to be a safe airway device in a manikin use.
When using the laryngeal tube and the intubating laryngeal mask airway (ILMA), the medium-size (maximum volume 1100 ml) versus adult (maximum volume 1500 ml) self-inflating bags resulted in significantly lower lung tidal volumes. No gastric inflation occurred when using both devices with either ventilation bag. The newly developed medium-size self-inflating bag may be an option to further reduce the risk of gastric inflation while maintaining sufficient lung ventilation. Both the ILMA and laryngeal tube proved to be valid alternatives for emergency airway management in the experimental model used.
emergency airway management; gastric regurgitation; intubating laryngeal mask airway; laryngeal tube; tidal volume
Six commercially available devices were tested to determine the alveolar oxygen concentration that is achieved and the volume of rebreathing that can occur in conditions simulating clinical use. All were tested at zero oxygen flow, since failure and interruption of the oxygen supply to such devices can occur in clinical use. In patients whose cardiorespiratory reserve is exhausted, any increase in dead space will be detrimental; for such patients devices should be selected which cannot cause rebreathing under any circumstances. Three of the devices tested could cause appreciable rebreathing, i.e., Oxyaire (B.L.B. pattern), Pneumask, and the M.C. mask. Claims made for the Pneumask and the M.C. mask were not substantiated in this study. With administration by nasal catheter changes in alveolar oxygen concentrations were found to be dependent on the percentage of mouth breathing by the subject. The Ventimask produced a consistent elevation of the alveolar oxygen percentage and did not cause any increase in the dead space.
The aim of this study was to investigate bladder wall thickness (BWT) and ultrasound estimated bladder weight (UEBW) values in healthy population with a portative ultrasound device and their relationship with demographic parameters.
Materials and Methods:
The study was carried out in Neurorehabilitation Clinic of Ege University Hospital. Ninety-five subjects (48 women and 47 men) aged between 18 and 56 were included in the study. BWT and UEBW were determined non-invasively with a portative ultrasound device; Bladder Scan BVM 6500 (Verathon Inc., WA, USA) at a frequency of 3.7 MHz at functional bladder capacity. These values were compared by gender, and their relation was assessed with age, body mass index (BMI) and parity.
Mean BWT was 2.0 ± 0.4 mm and UEBW was 44.6 ± 8.3 g at a mean volume of 338.0 ± 82.1 ml. Although higher results were obtained in men at higher bladder volumes, the results did not differ significantly by gender. Correlation analyses revealed statistically significant correlation between UEBW and age (r = 0.32). BWT was negatively correlated with volume (r = –0.50) and bladder surface area (r = –0.57). Also, statistically significant correlations were observed between UEBW and volume (r = 0.36), bladder surface area (r = 0.48) and BWT (r = 0.25).
Determined values of BWT and UEBW in healthy population are estimated with portative ultrasound devices, which are future promising, for their convenient, easy, non-invasive, time-efficient hand-held use for screening.
BladderScan BVM 6500; bladder wall thickness; ultrasound; ultrasound estimated bladder weight
Objective: To compare three devices for manual neonatal ventilation.
Design: Participants performed a two minute period of ventilation using a self inflating device, an anaesthesia bag with attached manometer, and a Neopuff device. An intubated neonatal mannequin, approximating a 1 kg infant with functional lungs, was used for the study. Target ventilation variables included a rate of 40 breaths per minute, peak inspiratory pressure (PIP) of 20 cm H2O, and positive end expiratory pressure (PEEP) of 4 cm H2O. The circuit was attached to a laptop computer for data recording.
Results: Thirty five participants were enrolled, including consultant neonatologists, paediatricians, and anaesthetists, paediatric and anaesthetic registrars, and neonatal nurses. The maximum PIP recorded using the self inflating bag, anaesthetic bag, and Neopuff device were 75.9, 35.5, and 22.4 cm H2O respectively. There were significant differences between the devices for mean PIP (30.7, 18.1, and 20.1 cm H2O), mean PEEP (0.2, 2.8, and 4.4 cm H2O), mean airway pressure (7.6, 8.5, and 10.9 cm H2O), % total breaths ⩽ 21 cm H2O PIP (39%, 92%, and 98%), and % total breaths ⩾ 30 cm H2O PIP (45%, 0, and 0). There was no difference between doctors and allied health professionals for the variables examined.
Conclusion: The anaesthetic bag with manometer and Neopuff device both facilitate accurate and reproducible manual ventilation. Self inflating devices without modifications are not as consistent by comparison and should incorporate a manometer and a PEEP device, particularly when used for resuscitation of very low birthweight infants.
Rebreathing of expired air may be a lethal hazard for prone
sleeping infants. This paper describes a mechanical model to simulate infant breathing, and examines the effects of bedding on exhaled air
retention. Under simulated rebreathing conditions, the model allows the
monitoring of raised carbon dioxide (CO2) inside an artificial lung-trachea system. Resulting levels of CO2
(although probably exaggerated in the mechanical model compared with an infant, due to the model's fixed breathing rate and volume) suggest that common bedding materials vary widely in inherent rebreathing potential. In face down tests, maximum airway CO2 ranged
from less than 5% on sheets and waterproof mattresses to over 25% on sheepskins, bean bag cushions, and some pillows and comforters. Concentrations of CO2 decreased with increasing head angle
of the doll, away from the face down position. Recreations of 29infant
death scenes also showed large CO2 increases on some
bedding materials, suggesting these infants could have died while rebreathing.
A rebreathing method for measuring carbon monoxide transfer factor (TLCO) and transfer coefficient (KCO) is evaluated. The test was performed on 42 subjects. Seventeen of these had normal lung function while the remainder suffered from various conditions, most having fibrosing alveolitis. No patients with severe airways obstruction were included in the group. The results were compared with single-breath measurements and close correlations were found between single-breath KCO and rebreathing KCO (r = 0.78, p less than 0.001) and between single-breath TLCO and rebreathing TLCO (r = 0.97, p less than 0.001). The reasons for discrepancies between single-breath and rebreathing values are discussed. It is concluded that measurement of rebreathing gas transfer is a useful supplement to routine tests of lung function, particularly in breathless patients with a small vital capacity.
Allogeneic hematopoietic cell transplantation (HCT) continues to be associated with substantial rates of non-relapse mortality (NRM). Numerous factors influence glucose metabolism among HCT recipients. We hypothesized that “malglycemia”, defined as hyperglycemia, hypoglycemia or increased glycemic variability, is associated with increased mortality in HCT patients.
In a retrospective cohort study, Cox regression was used to assess the association of malglycemia after transplant with day 200 NRM.
66,062 blood glucose (BG) measurements from 1175 adult allogeneic HCT recipients between 2000 and 2005 at the Fred Hutchinson Cancer Research Center were evaluated (median 0.55 values per patient-day, range 0.09-3.62). Overall, there were 215 cases of NRM by day 200 post-HCT and 601 deaths from any cause throughout observation. After adjustment for previously identified factors associated with NRM, all three components of malglycemia were associated with increased NRM when individually modeled as time-dependent covariates. Specifically, the hazard ratio for death was 1.93 for BG>200 mg/dl (p=0.0009) and 2.78 for BG>300 (p=0.0004) compared with BG 101-150 mg/dl. A minimum BG ≤ 89 was associated with a risk of day 200 NRM 2.17-times that of a minimum BG > 89 (p<0.0001). The upper quartile of glucose variability was associated with a 14.57-fold increase in risk of NRM by day 200 relative to the first quartile (p<0.0001).
These retrospective data indicate that malglycemia is associated with mortality following HCT. The applicability of these findings to other situations and whether correcting malglycemia in HCT can lead to reductions in mortality remain to be determined.
Hyperglycemia; Hypoglycemia; Glycemic Variability; Hematopoietic Cell Transplant; Infection; Mortality
Anemia is associated with morbidity and mortality and frequently leads to transfusion of erythrocytes. We sought to compare directly the effect of high inspired oxygen fraction vs. transfusion of erythrocytes on the anemia-induced increased heart rate (HR) in humans undergoing experimental acute isovolemic anemia.
We combined HR data from healthy subjects undergoing experimental isovolemic anemia in seven studies performed by our group. We examined HR changes associated with breathing 100% oxygen by non-rebreathing face mask vs. transfusion of erythrocytes at their nadir hemoglobin (Hb) concentration of 5 g/dL. Data were analyzed using a mixed-effects model.
HR had an inverse linear relationship to hemoglobin concentration with a mean increase of 3.9 beats per minute per gram of Hb (beats/min/g Hb) decrease (95% confidence interval [CI], 3.7 – 4.1 beats/min/g Hb), P < 0.0001. Return of autologous erythrocytes significantly decreased HR by 5.3 beats/min/g Hb (95% CI, 3.8 – 6.8 beats/min/g Hb) increase, P < 0.0001. HR at nadir Hb of 5.6 g/dL (95% CI, 5.5 – 5.7 g/dL) when breathing air (91.4 beats/min; 95% CI, 87.6 – 95.2 beats/min) was reduced by breathing 100% oxygen (83.0 beats/min; 95% CI, 79.0 -87.0 beats/min), P < 0.0001. The HR at hemoglobin 5.6 g/dL when breathing oxygen was equivalent to the HR at Hb 8.9 g/dL when breathing air.
High arterial oxygen partial pressure reverses the heart rate response to anemia, probably owing to its usability, rather than its effect on total oxygen content. The benefit of high arterial oxygen partial pressure has significant potential clinical implications for the acute treatment of anemia and results of transfusion trials.
Bystander resuscitation plays an important role in lifesaving cardiopulmonary resuscitation (CPR). A significant reduction in the "no-flow-time", quantitatively better chest compressions and an improved quality of ventilation can be demonstrated during CPR using supraglottic airway devices (SADs). Previous studies have demonstrated the ability of inexperienced persons to operate SADs after brief instruction. The aim of this pilot study was to determine whether an instruction manual consisting of four diagrams enables laypersons to operate a Laryngeal Mask Supreme® (LMAS) in the manikin.
An instruction manual of four illustrations with speech bubbles displaying the correct use of the LMAS was designed. Laypersons were handed a bag containing a LMAS, a bag mask valve device (BMV), a syringe prefilled with air and the instruction sheet, and were asked to perform and ventilate the manikin as displayed. Time to ventilation was recorded and degree of success evaluated.
A total of 150 laypersons took part. Overall 145 participants (96.7%) inserted the LMAS in the manikin in the right direction. The device was inserted inverted or twisted in 13 (8.7%) attempts. Eight (5.3%) individuals recognized this and corrected the position. Within the first 2 minutes 119 (79.3%) applicants were able to insert the LMAS and provide tidal volumes greater than 150 ml (estimated dead space). Time to insertion and first ventilation was 83.2 ± 29 s. No significant difference related to previous BLS training (P = 0.85), technical education (P = 0.07) or gender could be demonstrated (P = 0.25).
In manikin laypersons could insert LMAS in the correct direction after onsite instruction by a simple manual with a high success rate. This indicates some basic procedural understanding and intellectual transfer in principle. Operating errors (n = 91) were frequently not recognized and corrected (n = 77). Improvements in labeling and the quality of instructional photographs may reduce individual error and may optimize understanding.
Inflation and oesophageal pressures were recorded simultaneously during bag and mask resuscitation of 9 asphyxiated babies. After half a minute of standard inflation pressures, higher pressures were applied for at least 5 inflations by occluding the blow-off valve. No air entered the oesophagus until a high mean inflation pressure of 5.4 kPa was exceeded. These findings were confirmed in 4 fresh stillborn babies studied similarly. We conclude that resuscitation using bag and mask, applying pressures less than 3.5 kPa, should not lead to gastric distension.
The purpose of this human study was to investigate the effect of oxygen pretreatment in living kidney donors on early renal function of transplanted kidney. Sixty living kidney donor individuals were assigned to receive either 8–10 L/min oxygen (Group I) by a non-rebreather mask with reservoir bag intermittently for one hour at four times (20, 16, 12, and 1 hours before transplantation) or air (Group II). After kidney transplantation, urine output, blood urea nitrogen (BUN), serum creatinine, need to additional diuretics (NTADs) in the first 24 hours after transplantation, delayed graft function (DGF), the creatinine clearance (CrCL) on 10th day, and duration of hospital stay from the first posttransplant day till normalization of renal function was recorded and compared in two groups. Mean CrCL in posttransplant day 10, NTAD after 24 hours of transplantation, and urine output during 6 hours after operation were significantly better in Group I compared with Group II (P < .05). Also, DGF during the first week after operation and duration of hospital stay was less in Group I compared with Group II. Intermittent exposure of human living kidney donor to hyperoxic environment may improve renal function following kidney transplantation.
AIMS--The effect of rebreathing into a bag (RB) on retinal macular blood velocity was evaluated in healthy volunteers. METHODS--Ten normal volunteers, whose ages ranged from 17 to 34 years, performed RB over 135 to 260 seconds (mean (SD) 193 (38) seconds) while retinal macular blood velocity was determined non-invasively using the blue field simulation technique. RESULTS--Leucocyte velocity significantly increased (p < 0.05) at 2 minutes and at the end of RB by 53% (42%) and 92% (65%), respectively (95% confidence interval of the mean (CIM)). All subjects observed an increase in the density of leucocytes. At the end of RB, mean systolic brachial arterial pressure and heart rate were significantly increased by 24% (11%) and 37% (15%) respectively (p < 0.01). At 2 minutes, end tidal oxygen concentration in the exhaled air was 47% (8%) (95% CIM) below and carbon dioxide was 41% (16%) above baseline (p < 0.001). The RB produces a large increase in macular leucocyte velocity, suggesting an increase in blood flow. CONCLUSION--Although RB has some systemic risk due to hypoxia and hypercapnia, RB for a short period of 1 or 2 minutes might be of help in the treatment of retinal arterial obstructive diseases in young patients without cardiovascular disorders if other treatments do not show any beneficial effects.
Monitoring and assessing of patient respiratory function during conscious sedation are important because many drugs used for conscious sedation produce respiratory depression and subsequent hypoventilation. The purpose of this study is to assess the value of a dynamic air-pressure sensor for respiratory monitoring of clothed patients. Eight clothed adult volunteers were reclined on a dental chair positioned horizontally. The air bag for measuring air-pressure signals corresponding to respiration was placed on the seat back of the dental chair in the central lumbar area of the subject. The subject breathed through a face mask with a respirometer attached for measuring expiratory tidal volume. The air-pressure signals corresponding to respiration were obtained and the time integration values for air pressure during each expiration (∫Pexp) were calculated. The expiratory tidal volume (TVexp) was measured simultaneously by respirometer. The relationship between TVexp and ∫Pexp for each subject was assessed by a Pearson correlation coefficient. A strong correlation between TVexp and ∫Pexp was observed in all subjects. Measuring ∫Pexp by dynamic air-pressure sensor makes it possible to estimate respiratory volume breath by breath, and the respiratory pressure–time integral waveform was useful in visually monitoring the respiration pattern. We believe that in the future this device will be used to monitor respiratory physiology in clothed patients, contributing to safer sedative procedures.
Air-pressure sensor; Respiratory; Monitor; Nonrestrictively