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1.  The accuracy of pulse oximetry in emergency department patients with severe sepsis and septic shock: a retrospective cohort study 
Background
Pulse oximetry is routinely used to continuously and noninvasively monitor arterial oxygen saturation (SaO2) in critically ill patients. Although pulse oximeter oxygen saturation (SpO2) has been studied in several patient populations, including the critically ill, its accuracy has never been studied in emergency department (ED) patients with severe sepsis and septic shock. Sepsis results in characteristic microcirculatory derangements that could theoretically affect pulse oximeter accuracy. The purposes of the present study were twofold: 1) to determine the accuracy of pulse oximetry relative to SaO2 obtained from ABG in ED patients with severe sepsis and septic shock, and 2) to assess the impact of specific physiologic factors on this accuracy.
Methods
This analysis consisted of a retrospective cohort of 88 consecutive ED patients with severe sepsis who had a simultaneous arterial blood gas and an SpO2 value recorded. Adult ICU patients that were admitted from any Calgary Health Region adult ED with a pre-specified, sepsis-related admission diagnosis between October 1, 2005 and September 30, 2006, were identified. Accuracy (SpO2 - SaO2) was analyzed by the method of Bland and Altman. The effects of hypoxemia, acidosis, hyperlactatemia, anemia, and the use of vasoactive drugs on bias were determined.
Results
The cohort consisted of 88 subjects, with a mean age of 57 years (19 - 89). The mean difference (SpO2 - SaO2) was 2.75% and the standard deviation of the differences was 3.1%. Subgroup analysis demonstrated that hypoxemia (SaO2 < 90) significantly affected pulse oximeter accuracy. The mean difference was 4.9% in hypoxemic patients and 1.89% in non-hypoxemic patients (p < 0.004). In 50% (11/22) of cases in which SpO2 was in the 90-93% range the SaO2 was <90%. Though pulse oximeter accuracy was not affected by acidoisis, hyperlactatementa, anemia or vasoactive drugs, these factors worsened precision.
Conclusions
Pulse oximetry overestimates ABG-determined SaO2 by a mean of 2.75% in emergency department patients with severe sepsis and septic shock. This overestimation is exacerbated by the presence of hypoxemia. When SaO2 needs to be determined with a high degree of accuracy arterial blood gases are recommended.
doi:10.1186/1471-227X-10-9
PMCID: PMC2876142  PMID: 20444248
2.  Pulse oximetry: fundamentals and technology update 
Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD) of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs) or more in 5% of the examinations, which is in accordance with an error of 3%–4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns can be attributed to the empirical calibration process, which is performed on healthy volunteers. Other limitations of pulse oximetry include the presence of dyshemoglobins, which has been addressed by multiwavelength pulse oximetry, as well as low perfusion and motion artifacts that are partially rectified by sophisticated algorithms and also by reflection pulse oximetry.
doi:10.2147/MDER.S47319
PMCID: PMC4099100  PMID: 25031547
oxygen saturation; pulse oximetry; photoplethysmography; arterial blood; venous blood
3.  Do changes in pulse oximeter oxygen saturation predict equivalent changes in arterial oxygen saturation? 
Critical Care  2003;7(4):R67-R71.
Introduction
This study investigates the relation between changes in pulse oximeter oxygen saturation (SpO2) and changes in arterial oxygen saturation (SaO2) in the critically ill, and the effects of acidosis and anaemia on precision of using pulse oximetry to predict SaO2.
Patients and methods
Forty-one consecutive patients were recruited from a nine-bed general intensive care unit into a 2-month study. Patients with significant jaundice (bilirubin >40 μmol/l) or inadequate pulse oximetry tracing were excluded.
Results
A total of 1085 paired readings demonstrated only moderate correlation (r= 0.606; P < 0.01) between changes in SpO2 and those in SaO2, and the pulse oximeter tended to overestimate actual changes in SaO2. Anaemia increased the degree of positive bias whereas acidosis reduced it. However, the magnitude of these changes was small.
Conclusion
Changes in SpO2 do not reliably predict equivalent changes in SaO2 in the critically ill. Neither anaemia nor acidosis alters the relation between SpO2 and SaO2 to any clinically important extent.
PMCID: PMC270702  PMID: 12930558
acidosis; anaemia; arterial oxygen saturation; critical care; pulse oximetry
4.  Calibration-Free Pulse Oximetry Based on Two Wavelengths in the Infrared — A Preliminary Study 
Sensors (Basel, Switzerland)  2014;14(4):7420-7434.
The assessment of oxygen saturation in arterial blood by pulse oximetry (SpO2) is based on the different light absorption spectra for oxygenated and deoxygenated hemoglobin and the analysis of photoplethysmographic (PPG) signals acquired at two wavelengths. Commercial pulse oximeters use two wavelengths in the red and infrared regions which have different pathlengths and the relationship between the PPG-derived parameters and oxygen saturation in arterial blood is determined by means of an empirical calibration. This calibration results in an inherent error, and pulse oximetry thus has an error of about 4%, which is too high for some clinical problems. We present calibration-free pulse oximetry for measurement of SpO2, based on PPG pulses of two nearby wavelengths in the infrared. By neglecting the difference between the path-lengths of the two nearby wavelengths, SpO2 can be derived from the PPG parameters with no need for calibration. In the current study we used three laser diodes of wavelengths 780, 785 and 808 nm, with narrow spectral line-width. SaO2 was calculated by using each pair of PPG signals selected from the three wavelengths. In measurements on healthy subjects, SpO2 values, obtained by the 780–808 nm wavelength pair were found to be in the normal range. The measurement of SpO2 by two nearby wavelengths in the infrared with narrow line-width enables the assessment of SpO2 without calibration.
doi:10.3390/s140407420
PMCID: PMC4029673  PMID: 24763216
oxygen saturation; pulse oximetry; infrared; arterial blood; diode lasers; calibration
5.  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
6.  Evolution of Gas Exchange Abnormalities in Patients with Liver Cirrhosis Candidate for Liver Transplantation 
Background
Hypoxemia is common in patients with cirrhosis but the natural history of this syndrome is unknown. This study was conducted to evaluate the natural history of arterial oxygenation in patient with end stage liver cirrhosis.
Methods
Sixty eight patients with liver cirrhosis were followed up for 6-12 months. Arterial blood gas (ABG) and pulse oximetry were obtained on day of presentation and follow up.
Results
There were no significant changes in the oxygen saturation by pulse oximetry (SpO2), partial pressure of oxygen (PaO2) and alveolar arterial oxygen gradient (A-a O2) after 6-12 months. Mean arterial oxygen saturation (SaO2) in 46 patients was 95.42±1.92, and after follow up changed to 95.45±2.96. Thirty eight patients had SaO2 > 94% (mean 96.12±1.08 after 6-12 months changed to 95.66±2.58) ; 8 patients had SaO2 = 94 (mean 92.08±1.44 after 6-12 months changed to 94.46±4.47).
Conclusion
There were no significant changes in the SpO2, PaO2 and A-a O2 after 6-12 months.
PMCID: PMC3372036  PMID: 22737574
Blood gas; Cirrhosis; Hypoxemia
7.  Pulse Oximeter Oxygen Saturation in Prediction of Arterial Oxygen Saturation in Liver Transplant Candidates 
Hepatitis Monthly  2014;14(4):e15449.
Background:
Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement.
Objectives:
The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs.
Patients and Methods:
Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin saturation (SaO2) was recorded and compared with pulse oximetry oxyhemoglobin saturation (SpO2) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia.
Results:
Roc-derived SpO2 threshold of ≤ 94% can predict hypoxemia (PaO2 < 60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO2 threshold of ≤ 97% and detection of hypoxemia (PaO2 < 70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia.
Conclusions:
Provided that SpO2 is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.
doi:10.5812/hepatmon.15449
PMCID: PMC3989597  PMID: 24748894
Blood Gas Monitoring, Transcutaneous; Liver Cirrhosis; Oximetry; hypoxemia; Liver Transplantation
8.  Optimal Clinical Time for Reliable Measurement of Transcutaneous CO2 with Ear Probes: Counterbalancing Overshoot and the Vasodilatation Effect 
Sensors (Basel, Switzerland)  2010;10(1):491-500.
OBJECTIVES:
To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO2) and transcutaneous CO2 (TcPCO2) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO2).
EXPERIMENTAL SECTION:
Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO2 and TcPCO2 with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1–1.9 mm Hg); (b) moderate (2–4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO2 and TcPCO2 and arterial values of PaCO2 and SpO2. The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement.
RESULTS:
The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV1: 72.9 ± 23.9%; FEV1/FVC: 70 ± 15.5%. ABG: PaO2: 82.6 ± 13.2; PaCO2: 39.9.1 ± 4.8 mmHg; SaO2: 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO2 was −0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO2, measurements were reliable at minute 2.
CONCLUSIONS:
The optimal clinical reading measurement recommended for the ear lobe TcPCO2 measurement ranges between minute 12 and 14. The SpO2 measurement can be performed at minute 2.
doi:10.3390/s100100491
PMCID: PMC3270853  PMID: 22315552
transcutaneous CO2; optimal reading time; overshoot phenomenon
9.  Pulse Oximetry: Evaluation of Accuracy during Outpatient General Anesthesia for Oral Surgery 
Anesthesia Progress  1988;35(2):53-60.
Pulse oximetry has been shown to be accurate under steady state conditions. In this study, the accuracy of four pulse oximeters are evaluated and compared during outpatient general anesthesia for third molar extractions. The oximeters evaluated are the Nellcor N-100, the Ohmeda 3700, the Novametrix model 500, and the Bird 4400 portable pulse oximeter.
Ultralight general anesthesia for oral surgery presents a unique challenge for respiratory monitoring in that patients are often not intubated and commonly experience periods of hyper- and hypoventilation. Airway obstruction, apnea, and laryngospasm may occur easily and patients often vocalize and move during surgery. Because hypoxemia is the primary cause of morbidity and mortality during anesthesia, an accurate, continuous, and noninvasive monitor of oxygenation is critical to risk management.
Twenty ASA class I and II patients underwent outpatient general anesthesia for third molar removal using nitrous oxide-oxygen, midazolam, fentanyl, and methohexital. Arterial blood samples were obtained at five-minute intervals during anesthesia, as well as any time a desaturation of >5% occurred, for measurement of arterial SaO2 with an IL282 CO-Oximeter. These values were compared with simultaneously recorded saturations observed for each pulse oximeter. A total of 122 arterial samples were obtained over a range of PaO2 from 52-323 mm Hg and observed saturations of 70-100%.
The Bird 4400 portable pulse oximeter proved to be the most accurate and reliably predicted arterial saturation under these conditions (y = 1.03x - 2.8, r = 0.85). The Novametrix model 500 pulse oximeter also demonstrated a high degree of accuracy by linear regression analysis, but displayed the lowest correlation coefficient (spread of data points) overall (y = 0.97x + 2.8, r = 0.80.) The Nellcor N-100 pulse oximeter also proved to be highly accurate. (y = 1.05x - 4.1, r = 0.84.) In contrast, regression analysis of the observed saturations obtained with the Ohmeda 3700 pulse oximeter revealed that this unit significantly underestimated arterial saturation (y = 1.20x - 19.6, r = 0.83.)
This study demonstrates that despite the rigorous conditions imposed by outpatient general anesthesia for oral surgery, three of the pulse oximeters tested were linearly accurate in predicting arterial oxyhemoglobin saturation over the range of 70-100%. The Ohmeda 3700 was found to significantly underestimate arterial saturation.
Images
PMCID: PMC2148593  PMID: 3166346
10.  Re-examination of the incidence of exercise-induced hypoxaemia in highly trained subjects. 
The purpose of this study was to examine the occurrence of exercise-induced hypoxaemia (EIH) during maximal exercise in highly trained athletes. Eleven trained cyclists (mean(s.d.) age 23(3.5) years; mean(s.d.) VO2max 66.9(4.8) ml kg-1min-1) performed a continuous, multistage (270 kpm min-1) cycle ergometer test to exhaustion. Measurements of arterial oxygen-haemoglobin saturation (%HbO2) were obtained simultaneously at rest, every 2 min during exercise, and at maximum exercise capacity from arterial blood sampling (%SaO2) and ear oximetry (%SpO2). Exercise induced hypoxaemia (%HbO2 < or = 91%) was present in 64% of the athletes examined when EIH was determined using pulse oximetry, whereas none of the subjects exhibited EIH when %HbO2 was determined using arterial blood. At rest the values for %HbO2 were similar with mean(s.d.) %SaO2 being 97.3(0.6)% and mean(s.d.) %SpO2 being 96.5(1.6)%. During exercise, statistically significant differences were found for %HbO2 between arterial blood and ear oximetry at the 6-min, 8-min, and maximal exercise sampling times (repeated measures analysis of variance, P < 0.05). The results indicate that ear oximetry overestimates the incidence of EIH and underestimates the oxyhaemoglobin saturation in highly trained cyclists during exercise in comparison with those measurements made from arterial blood.
PMCID: PMC1332180  PMID: 8242272
11.  HbA1c is associated with severity of obstructive sleep apnea hypopnea syndrome in nondiabetic men 
The aim of this study was to examine the potential correlation of sleep characteristics with glucose metabolism in nondiabetic men with obstructive sleep apnea syndrome (OSAS). Included were 31 male patients (mean age 46.7 ±11 years), recently diagnosed with OSAS by full polysomnography. There was a significant correlation of fasting glucose and glycosylated hemoglobin (HbA1c) levels with arousal index (P = 0.047 and P =0.014, respectively). Moreover, HbA1c levels were correlated with apnea hypopnea index (P =0.009), a widely accepted marker of the severity of OSAS, and with percentage of sleep time with saturation of hemoglobin with oxygen as measured by pulse oximetry (SpO2) < 90% (t < 90%) ( P =0.010). Finally, glucose and HbA1c levels showed a significant negative correlation with average SpO2 (P =0.013 and P = 0.012, respectively) and, additionally, glucose levels with minimum SpO 2 (P =0.027) during sleep. In conclusion, severity of OSAS among nondiabetic men is associated with increased HbA1c levels and increased fasting glucose. Thus, severity of OSAS may be an additional marker of cardiovascular risk, as well as of future diabetes, in these subjects. However, further work is needed to confirm the clinical significance of these observations.
PMCID: PMC2747393  PMID: 19774216
obstructive sleep apnea syndrome; glucose metabolism; glycated hemoglobin; sleep disordered breathing
12.  Report of the Committee on the Classification and Diagnostic Criteria of Diabetes Mellitus 
Abstract
Concept of Diabetes Mellitus:
Diabetes mellitus is a group of diseases associated with various metabolic disorders, the main feature of which is chronic hyperglycemia due to insufficient insulin action. Its pathogenesis involves both genetic and environmental factors. The long‐term persistence of metabolic disorders can cause susceptibility to specific complications and also foster arteriosclerosis. Diabetes mellitus is associated with a broad range of clinical presentations, from being asymptomatic to ketoacidosis or coma, depending on the degree of metabolic disorder.
Classification (Tables 1 and 2, and Figure 1):
 Etiological classification of diabetes mellitus and glucose metabolism disorders
Note: Those that cannot at present be classified as any of the above are called unclassifiable.
The occurrence of diabetes‐specific complications has not been confirmed in some of these conditions.
 Diabetes mellitus and glucose metabolism disorders due to other specific mechanisms and diseases
The occurrence of diabetes‐specific complications has not been confirmed in some of these conditions.
 A scheme of the relationship between etiology (mechanism) and patho‐physiological stages (states) of diabetes mellitus. Arrows pointing right represent worsening of glucose metabolism disorders (including onset of diabetes mellitus). Among the arrow lines, indicates the condition classified as ‘diabetes mellitus’. Arrows pointing left represent improvement in the glucose metabolism disorder. The broken lines indicate events of low frequency. For example, in type 2 diabetes mellitus, infection can lead to ketoacidosis and require temporary insulin treatment for survival. Also, once diabetes mellitus has developed, it is treated as diabetes mellitus regardless of improvement in glucose metabolism, therefore, the arrow lines pointing left are filled in black. In such cases, a broken line is used, because complete normalization of glucose metabolism is rare.
The classification of glucose metabolism disorders is principally derived from etiology, and includes staging of pathophysiology based on the degree of deficiency of insulin action. These disorders are classified into four groups: (i) type 1 diabetes mellitus; (ii) type 2 diabetes mellitus; (iii) diabetes mellitus due to other specific mechanisms or diseases; and (iv) gestational diabetes mellitus. Type 1 diabetes is characterized by destruction of pancreatic β‐cells. Type 2 diabetes is characterized by combinations of decreased insulin secretion and decreased insulin sensitivity (insulin resistance). Glucose metabolism disorders in category (iii) are divided into two subgroups; subgroup A is diabetes in which a genetic abnormality has been identified, and subgroup B is diabetes associated with other pathologic disorders or clinical conditions. The staging of glucose metabolism includes normal, borderline and diabetic stages depending on the degree of hyperglycemia occurring as a result of the lack of insulin action or clinical condition. The diabetic stage is then subdivided into three substages: non‐insulin‐ requiring, insulin‐requiring for glycemic control, and insulin‐dependent for survival. The two former conditions are called non‐insulin‐dependent diabetes and the latter is known as insulin‐dependent diabetes. In each individual, these stages may vary according to the deterioration or the improvement of the metabolic state, either spontaneously or by treatment.
Diagnosis (Tables 3–7 and Figure 2):
 Criteria of fasting plasma glucose levels and 75 g oral glucose tolerance test 2‐h value
*Casual plasma glucose ≥200 mg/dL (≥11.1 mmol/L) and HbA1c≥6.5% are also regarded as to indicate diabetic type.
Even for normal type, if 1‐h value is 180 mg/dL (10.0 mmol/L), the risk of progression to diabetes mellitus is greater than for <180 mg/dL (10.0 mmol/L) and should be treated as with borderline type (follow‐up observation, etc.). Fasting plasma glucose level of 100–109 mg/dL (5.5–6.0 mmol/L) is called ‘high‐normal’: within the range of normal fasting plasma glucose.
Plasma glucose level after glucose load in oral glucose tolerance test (OGTT) is not included in casual plasma glucose levels. The value for HbA1c (%) is indicated with 0.4% added to HbA1c (JDS) (%).
 Procedures for diagnosing diabetes mellitus
*The value for HbA1c (%) is indicated with 0.4% added to HbA1c (JDS) (%). **Hyperglycemia must be confirmed in a non‐stressful condition. OGTT, oral glucose tolerance test.
 Disorders and conditions associated with low HbA1c values
 Situations where a 75‐g oral glucose tolerance test is recommended
*The value for HbA1c (%) is indicated with 0.4% added to HbA1c (JDS) (%).
 Definition and diagnostic criteria of gestational diabetes mellitus
(IADPSG Consensus Panel, Reference 42, partly modified with permission of Diabetes Care).
 Flow chart outlining steps in the clinical diagnosis of diabetes mellitus. *The value for HbA1c (%) is indicated with 0.4% added to HbA1c (JDS) (%).
Categories of the State of Glycemia:  Confirmation of chronic hyperglycemia is essential for the diagnosis of diabetes mellitus. When plasma glucose levels are used to determine the categories of glycemia, patients are classified as having a diabetic type if they meet one of the following criteria: (i) fasting plasma glucose level of ≥126 mg/dL (≥7.0 mmol/L); (ii) 2‐h value of ≥200 mg/dL (≥11.1 mmol/L) in 75 g oral glucose tolerance test (OGTT); or (iii) casual plasma glucose level of ≥200 mg/dL (≥11.1 mmol/L). Normal type is defined as fasting plasma glucose level of <110 mg/dL (<6.1 mmol/L) and 2‐h value of <140 mg/dL (<7.8 mmol/L) in OGTT. Borderline type (neither diabetic nor normal type) is defined as falling between the diabetic and normal values. According to the current revision, in addition to the earlier listed plasma glucose values, hemoglobin A1c (HbA1c) has been given a more prominent position as one of the diagnostic criteria. That is, (iv) HbA1c≥6.5% is now also considered to indicate diabetic type. The value of HbA1c, which is equivalent to the internationally used HbA1c (%) (HbA1c [NGSP]) defined by the NGSP (National Glycohemoglobin Standardization Program), is expressed by adding 0.4% to the HbA1c (JDS) (%) defined by the Japan Diabetes Society (JDS).
Subjects with borderline type have a high rate of developing diabetes mellitus, and correspond to the combination of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) noted by the American Diabetes Association (ADA) and WHO. Although borderline cases show few of the specific complications of diabetes mellitus, the risk of arteriosclerosis is higher than those of normal type. When HbA1c is 6.0–6.4%, suspected diabetes mellitus cannot be excluded, and when HbA1c of 5.6–5.9% is included, it forms a group with a high risk for developing diabetes mellitus in the future, even if they do not have it currently.
Clinical Diagnosis:  1 If any of the criteria for diabetic type (i) through to (iv) is observed at the initial examination, the patient is judged to be ‘diabetic type’. Re‐examination is conducted on another day, and if ‘diabetic type’ is reconfirmed, diabetes mellitus is diagnosed. However, a diagnosis cannot be made only by the re‐examination of HbA1c alone. Moreover, if the plasma glucose values (any of criteria [i], [ii], or [iii]) and the HbA1c (criterion [iv]) in the same blood sample both indicate diabetic type, diabetes mellitus is diagnosed based on the initial examination alone. If HbA1c is used, it is essential that the plasma glucose level (criteria [i], [ii] or [iii]) also indicates diabetic type for a diagnosis of diabetes mellitus. When diabetes mellitus is suspected, HbA1c should be measured at the same time as examination for plasma glucose.2 If the plasma glucose level indicates diabetic type (any of [i], [ii], or [iii]) and either of the following conditions exists, diabetes mellitus can be diagnosed immediately at the initial examination.• The presence of typical symptoms of diabetes mellitus (thirst, polydipsia, polyuria, weight loss)• The presence of definite diabetic retinopathy3 If it can be confirmed that the above conditions 1 or 2 existed in the past, diabetes mellitus can be diagnosed or suspected regardless of the current test results.4 If the diagnosis of diabetes cannot be established by these procedures, the patient is followed up and re‐examined after an appropriate interval.5 The physician should assess not only the presence or absence of diabetes, but also its etiology and glycemic stage, and the presence and absence of diabetic complications or associated conditions.
Epidemiological Study:  For the purpose of estimating the frequency of diabetes mellitus, ‘diabetes mellitus’ can be substituted for the determination of ‘diabetic type’ from a single examination. In this case, HbA1c≥6.5% alone can be defined as ‘diabetes mellitus’.
Health Screening:  It is important not to misdiagnose diabetes mellitus, and thus clinical information such as family history and obesity should be referred to at the time of screening in addition to an index for plasma glucose level.
Gestational Diabetes Mellitus:  There are two hyperglycemic disorders in pregnancy: (i) gestational diabetes mellitus (GDM); and (ii) diabetes mellitus. GDM is diagnosed if one or more of the following criteria is met in a 75 g OGTT during pregnancy:
1 Fasting plasma glucose level of ≥92 mg/dL (5.1 mmol/L)2 1‐h value of ≥180 mg/dL (10.0 mmol/L)3 2‐h value of ≥153 mg/dL (8.5 mmol/L)
However, diabetes mellitus that is diagnosed by the clinical diagnosis of diabetes mellitus defined earlier is excluded from GDM. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00074.x, 2010)
doi:10.1111/j.2040-1124.2010.00074.x
PMCID: PMC4020724  PMID: 24843435
Diabetes mellitus; Clinical diagnosis; HbA1c
13.  Effect of simulated commercial flight on oxygenation in patients with interstitial lung disease and chronic obstructive pulmonary disease 
Thorax  2004;59(11):966-970.
Background: Commercial aircraft cabins provide a hostile environment for patients with underlying respiratory disease. Although there are algorithms and guidelines for predicting in-flight hypoxaemia, these relate to chronic obstructive pulmonary disease (COPD) and data for interstitial lung disease (ILD) are lacking. The purpose of this study was to evaluate the effect of simulated cabin altitude on subjects with ILD at rest and during a limited walking task.
Methods: Fifteen subjects with ILD and 10 subjects with COPD were recruited. All subjects had resting arterial oxygen pressure (PaO2) of >9.3 kPa. Subjects breathed a hypoxic gas mixture containing 15% oxygen with balance nitrogen for 20 minutes at rest followed by a 50 metre walking task. Pulse oximetry (SpO2) was monitored continuously with testing terminated if levels fell below 80%. Arterial blood gas tensions were taken on room air at rest and after the resting and exercise phases of breathing the gas mixture.
Results: In both groups there was a statistically significant decrease in arterial oxygen saturation (SaO2) and PaO2 from room air to 15% oxygen at rest and from 15% oxygen at rest to the completion of the walking task. The ILD group differed significantly from the COPD group in resting 15% oxygen SaO2, PaO2, and room air pH. Means for both groups fell below recommended levels at both resting and when walking on 15% oxygen.
Conclusion: Even in the presence of acceptable arterial blood gas tensions at sea level, subjects with both ILD and COPD fall below recommended levels of oxygenation when cabin altitude is simulated. This is exacerbated by minimal exercise. Resting sea level arterial blood gas tensions are similarly poor in both COPD and ILD for predicting the response to simulated cabin altitude.
doi:10.1136/thx.2004.022210
PMCID: PMC1746875  PMID: 15516473
14.  Pharyngeal oxygen administration increases the time to serious desaturation at intubation in acute lung injury: an experimental study 
Critical Care  2010;14(3):R93.
Introduction
Endotracheal intubation in critically ill patients is associated with severe life-threatening complications in about 20%, mainly due to hypoxemia. We hypothesized that apneic oxygenation via a pharyngeal catheter during the endotracheal intubation procedure would prevent or increase the time to life-threatening hypoxemia and tested this hypothesis in an acute lung injury animal model.
Methods
Eight anesthetized piglets with collapse-prone lungs induced by lung lavage were ventilated with a fraction of inspired oxygen of 1.0 and a positive end-expiratory pressure of 5 cmH2O. The shunt fraction was calculated after obtaining arterial and mixed venous blood gases. The trachea was extubated, and in randomized order each animal received either 10 L oxygen per minute or no oxygen via a pharyngeal catheter, and the time to desaturation to pulse oximeter saturation (SpO2) 60% was measured. If SpO2 was maintained at over 60%, the experiment ended when 10 minutes had elapsed.
Results
Without pharyngeal oxygen, the animals desaturated after 103 (88-111) seconds (median and interquartile range), whereas with pharyngeal oxygen five animals had a SpO2 > 60% for the 10-minute experimental period, one animal desaturated after 7 minutes, and two animals desaturated within 90 seconds (P < 0.016, Wilcoxon signed rank test). The time to desaturation was related to shunt fraction (R2 = 0.81, P = 0.002, linear regression); the animals that desaturated within 90 seconds had shunt fractions >40%, whereas the others had shunt fractions <25%.
Conclusions
In this experimental acute lung injury model, pharyngeal oxygen administration markedly prolonged the time to severe desaturation during apnea, suggesting that this technique might be useful when intubating critically ill patients with acute respiratory failure.
doi:10.1186/cc9027
PMCID: PMC2911730  PMID: 20497538
15.  Pulse oximeter and transcutaneous arterial oxygen measurements in neonatal and paediatric intensive care. 
Archives of Disease in Childhood  1987;62(9):882-888.
Pulse oximeter (SaO2P) measurements were compared with direct arterial line oxygen saturation (SaO2) from co-oximeters in 92 instances in 43 patients, and with arterial line oxygen measurements (PaO2) in 169 instances in 81 patients. The mean (SD) absolute difference between SaO2P and SaO2 was 2.6% (2.4) after attempt to correct for the co-oximeter falsely measuring a proportion of fetal haemoglobin as carboxy haemoglobin. For 19 infants and children greater than or equal to 5 months old, who have very little fetal haemoglobin, the mean (SD) absolute difference of 27 comparisons was 1.8% (2.1). Comparison of SaO2P and PaO2 measurements in 46 instances when PaO2 was less than 6.67 kPa showed SaO2 to be less than 90% on 40 occasions. In 24 instances when PaO2 was greater than or equal to 13.3 kPa the SaO2P was greater than or equal to 98% on 22 occasions. In 23 infants undergoing neonatal intensive care, transcutaneous oxygen monitors were compared with arterial PO2 measurements in 60 instances. The mean (SD) absolute difference between PaO2 and transcutaneous oxygen measurements was 1.60 kPa (1.73). Ten of the 60 comparisons had differences greater than 2.67 kPa and three greater than 5.33 kPa (maximum 8.40 kPa). Pulse oximetry is a clinically useful technique for managing oxygenation but further studies are needed to confirm its safety in premature infants at risk of retinopathy of prematurity.
PMCID: PMC1778595  PMID: 3674942
16.  Oxygen Saturation in Healthy Children Aged 5 to 16 Years Residing in Huayllay, Peru at 4340 m 
Abstract
Schult, Sandra, and Carlos Canelo-Aybar. Oxygen saturation in healthy chidren aged 5 to 6 years residing in Huayllay, Peru, at 4340 m. High Alt. Med. Biol. 12:89–92, 2011.—Hypoxemia is a major life-threatening complication of childhood pneumonia. The threshold points for hypoxemia vary with altitude. However, few published data describe that normal range of variation. The purpose of this study was to establish reference values of normal mean Sao2 levels and an approximate cutoff point to define hypoxemia for clinical purposes above 4300 meters above sea level (masl).
Children aged 5 to 16 yr were examined during primary care visits at the Huayllay Health Center. Huayllay is a rural community located at 4340 m in the province of Pasco in the Peruvian Andes. We collected basic sociodemographic data and evaluated three outcomes: arterial oxygen saturation (Sao2) with a pulse oximeter, heart rate, and respiratory rate. Comparisons of main outcomes among age groups (5–6, 7–8, 9–10, 11–12, 13–14, and 15–16 yr) and sex were performed using linear regression models. The correlation of Sao2 with heart rate and respiration rate was established by Pearson's correlation test.
We evaluated 583 children, of whom 386 were included in the study. The average age was 10.3 yr; 55.7% were female. The average Sao2, heart rate, and respiratory rate were 85.7% (95% CI: 85.2–86.2), 80.4/min (95% CI: 79.0–81.9), and 19.9/min (95% CI: 19.6–20.2), respectively. Sao2 increased with age (p < 0.001). No differences by sex were observed. The mean minus two standard deviations of Sao2 (threshold point for hypoxemia) ranged from 73.8% to 81.8% by age group.
At 4300 m, the reference values for hypoxemia may be 14.2% lower than at sea level. This difference must be considered when diagnosing hypoxemia or deciding oxygen supplementation at high altitude. Other studies are needed to determine whether this reference value is appropriate for clinical use.
doi:10.1089/ham.2009.1094
PMCID: PMC3114159  PMID: 21452970
Oxygen saturation, pulse oximetry; children at high altitude
17.  Exercise peripheral oxygen saturation (SpO2) accurately reflects arterial oxygen saturation (SaO2) and predicts mortality in systemic sclerosis 
Thorax  2009;64(7):626-630.
Background
Measures of oxygenation have not been assessed for prognostic significance in systemic sclerosis-related interstitial lung disease (SSc-ILD).
Methods
83 subjects with SSc-ILD performed a maximal cardiopulmonary exercise test with an arterial line. The agreement between peripheral oxygen saturation (SpO2) and arterial oxygen saturation (SaO2) was examined and survival differences between subgroups of subjects stratified on SpO2 were analysed. Cox proportional hazards analyses were used to examine the prognostic capabilities of SpO2.
Results
At maximal exercise the mean (SD) difference between SpO2 and SaO2 was 2.98 (2.98) and only 15 subjects had a difference of >4 points. The survival of subjects with SSc-ILD whose maximum exercise SpO2 (SpO2max) fell below 89% or whose SpO2max fell >4 points from baseline was worse than subjects in comparator groups (log rank p = 0.01 and 0.01, respectively). The hazard of death during the median 7.1 years of follow-up was 2.4 times greater for subjects whose SpO2max fell below 89% (hazard ratio 2.4, 95% CI 1.1 to 4.9, p = 0.02) or whose SpO2max fell >4 points from baseline (hazard ratio 2.4, 95% CI 1.1 to 5.0, p = 0.02).
Conclusion
In patients with SSc-ILD, SpO2 is an adequate reflection of SaO2 and radial arterial lines need not be inserted during cardiopulmonary exercise tests in these patients. Given the ease of measurement and its prognostic value, SpO2 should be considered as a meaningful clinical and research outcome in patients with SSc-ILD.
doi:10.1136/thx.2008.111393
PMCID: PMC3667987  PMID: 19359269
18.  Development of a Screening Tool for Sleep Disordered Breathing in Children Using the Phone Oximeter™ 
PLoS ONE  2014;9(11):e112959.
Background
Sleep disordered breathing (SDB) can lead to daytime sleepiness, growth failure and developmental delay in children. Polysomnography (PSG), the gold standard to diagnose SDB, is a highly resource-intensive test, confined to the sleep laboratory.
Aim
To combine the blood oxygen saturation (SpO2) characterization and cardiac modulation, quantified by pulse rate variability (PRV), to identify children with SDB using the Phone Oximeter, a device integrating a pulse oximeter with a smartphone.
Methods
Following ethics approval and informed consent, 160 children referred to British Columbia Children's Hospital for overnight PSG were recruited. A second pulse oximeter sensor applied to the finger adjacent to the one used for standard PSG was attached to the Phone Oximeter to record overnight pulse oximetry (SpO2 and photoplethysmogram (PPG)) alongside the PSG.
Results
We studied 146 children through the analysis of the SpO2 pattern, and PRV as an estimate of heart rate variability calculated from the PPG. SpO2 variability and SpO2 spectral power at low frequency, was significantly higher in children with SDB due to the modulation provoked by airway obstruction during sleep (p-value ). PRV analysis reflected a significant augmentation of sympathetic activity provoked by intermittent hypoxia in SDB children. A linear classifier was trained with the most discriminating features to identify children with SDB. The classifier was validated with internal and external cross-validation, providing a high negative predictive value (92.6%) and a good balance between sensitivity (88.4%) and specificity (83.6%). Combining SpO2 and PRV analysis improved the classification performance, providing an area under the receiver operating characteristic curve of 88%, beyond the 82% achieved using SpO2 analysis alone.
Conclusions
These results demonstrate that the implementation of this algorithm in the Phone Oximeter will provide an improved portable, at-home screening tool, with the capability of monitoring patients over multiple nights.
doi:10.1371/journal.pone.0112959
PMCID: PMC4234680  PMID: 25401696
19.  Oxygen saturation trends in the first hour of life in healthy full-term neonates born at moderate altitude 
Background: Transition from a parallel circulation in utero to an in-series circulation immediately after birth is partly an oxygen-dependent process. Relative hypoxemia with increasing altitude above sea level exerts a certain degree of stress on oxygen-dependent metabolic processes throughout the body.
Objective: The present study aimed to determine the reference values for oxygen saturation and the pre-ductal and post-ductal oxygen saturation trends during the first 60 min of life in healthy full-term neonates born at moderate altitude (1500-2500 m) using pulse oximetry.
Methods: This descriptive study was carried out over a period of three months started from July 2011 in the Neonatology Department of King Abdulaziz Specialist Hospital, Taif, Saudi Arabia. In this observational study, arterial oxygen saturation in the right hand and right foot of each infant was recorded by pulse oximetry immediately after birth and continuously within the first 60 min of life. The respiratory rate, heart rate, and blood pressure were measured at birth and at 1 h after birth. Cord blood gas and haemoglobin levels were also measured.
Results: The study was conducted in a hospital situated at an altitude of 1640 m above sea level. Immediately after birth, the mean pre-ductal SpO2 in the right hand was 68% (51–80%); in the right foot, the mean post-ductal SpO2 was 60% (40–77%). This difference was statistically significant (p < 0.01); however, it became statistically insignificant at 20 min (4–45 min) and disappeared at 25 min, when the SpO2 in both limbs equalised at 88% (83–96%). SpO2 levels > 94% were reached after 13 min (4–35) min pre-ductally and after 22 min (10–45 min) post-ductally. The mean respiratory rate, heart rate, and mean blood pressure at birth were 56/min, 140/min, and 34 mmHg, respectively; at 60 min, they were 40/min, 123/min, and 47 mmHg, respectively.
Conclusion: This study defined normal range of SpO2 values in healthy full-term neonates born at moderate altitude in the first 60 minutes of life. These are expected to serve as base line data for normal neonates born at similar altitudes. With regard to pre-ductal and post-ductal oxygen saturation levels, cut-off values lower than those used at sea level should be adopted for neonates born at moderate altitudes.
PMCID: PMC3817766  PMID: 24353656
Pulse oximetry; Cardiopulmonary transition; Moderate altitude; Oxygen saturation
20.  Hematological and Genetic Predictors of Daytime Hemoglobin Saturation in Tanzanian Children with and without Sickle Cell Anemia 
ISRN Hematology  2013;2013:472909.
Low hemoglobin oxygen saturation (SpO2) is common in Sickle Cell Anemia (SCA) and associated with complications including stroke, although determinants remain unknown. We investigated potential hematological, genetic, and nutritional predictors of daytime SpO2 in Tanzanian children with SCA and compared them with non-SCA controls. Steady-state resting pulse oximetry, full blood count, transferrin saturation, and clinical chemistry were measured. Median daytime SpO2 was 97% (IQ range 94–99%) in SCA (N = 458), lower (P < 0.0001) than non-SCA (median 99%, IQ range 98–100%; N = 394). Within SCA, associations with SpO2 were observed for hematological variables, transferrin saturation, body-mass-index z-score, hemoglobin F (HbF%), genotypes, and hemolytic markers; mean cell hemoglobin (MCH) explained most variability (P < 0.001, Adj r2 = 0.09). In non-SCA only age correlated with SpO2. α-thalassemia 3.7 deletion highly correlated with decreased MCH (Pearson correlation coefficient −0.60, P < 0.0001). In multivariable models, lower SpO2 correlated with higher MCH (β-coefficient −0.32, P < 0.001) or with decreased copies of α-thalassemia 3.7 deletion (β-coefficient 1.1, P < 0.001), and independently in both models with lower HbF% (β-coefficient 0.15, P < 0.001) and Glucose-6-Phosphate Dehydrogenase genotype (β-coefficient −1.12, P = 0.012). This study provides evidence to support the hypothesis that effects on red cell rheology are important in determining SpO2 in children with SCA. Potential mechanisms and implications are discussed.
doi:10.1155/2013/472909
PMCID: PMC3649307  PMID: 23691341
21.  A preliminary study on the monitoring of mixed venous oxygen saturation through the left main bronchus 
Critical Care  2005;10(1):R7.
Introduction
The study sought to assess the feasibility and accuracy of measuring mixed venous oxygen saturation (SvO2) through the left main bronchus (SpO2trachea)
Methods
Twenty hybrid pigs of each sex were studied. After anesthesia, a Robertshaw double-lumen tracheal tube with a single-use pediatric pulse oximeter attached to the left lateral surface was introduced toward the left main bronchus of the pig by means of a fibrobronchoscope. Measurements of SpO2trachea and oxygen saturation from pulmonary artery samples (SvO2blood) were performed with an intracuff pressure of 0 to 60 cmH2O. After equilibration, hemorrhagic shock was induced in these pigs by bleeding to a mean arterial blood pressure of 40 mmHg. With the intracuff pressure maintained at 60 cmH2O, SpO2trachea and SvO2blood were obtained respectively during the pre-shock period, immediately after the onset of shock, 15 and 30 minutes after shock, and 15, 30, and 60 minutes after resuscitation.
Results
SpO2trachea was the same as SvO2blood at an intracuff pressure of 10, 20, 40, and 60 cmH2O, but was reduced when the intracuff pressure was zero (p < 0.001 compared with SvO2blood) in hemodynamically stable states. Changes of SpO2trachea and SvO2blood corresponded with varieties of cardiac output during the hemorrhagic shock period. There was a significant correlation between the two methods at different time points.
Conclusion
Measurement of the left main bronchus SpO2 is feasible and provides similar readings to SvO2blood in hemodynamically stable or in low saturation states. Tracheal oximetry readings are not primarily derived from the tracheal mucosa. The technique merits further evaluation.
doi:10.1186/cc3914
PMCID: PMC1550812  PMID: 16356208
22.  Evaluation of the Ohmeda 3700 pulse oximeter. 
Thorax  1987;42(11):892-896.
Arterial oxygen saturation values (Sao2) from 60% to 98% were measured by the Ohmeda 3700 pulse oximeter with the three types of probe available and compared with values of oxygen saturation estimated from direct arterial sampling (arterial oxygen and carbon dioxide tensions and pH) on 65 occasions. The response time of the oximeter was measured after a sudden rise in inspired oxygen concentration. Artefact rejection was assessed by arterial compression proximal to the probe site, and by simultaneous recordings of overnight Sao2 on opposite hands. The ability to recreate patterns of oscillating Sao2 from the data stored in the oximeter was also investigated. With the best probe system the oximeter measured Sao2, relative to arterial values estimated from Pao2, with a mean (SD) difference of -0.4% (1.8%). The response time was comparable with those of previous oximeters. It was not possible to generate artefactual dips in excess of 2% Sao2, and the dual overnight recordings rarely showed even small dips on one tracing alone. The stored data can recreate oscillating Sao2 signals with wavelengths down to about 35 seconds, but not below. The Ohmeda 3700 pulse oximeter appears to be suitable for unattended overnight recordings of Sao2.
PMCID: PMC461017  PMID: 3424271
23.  Peripheral venous blood gases and pulse-oximetry in acute cardiogenic pulmonary oedema 
Background:
The role of venous blood gases as an alternative to arterial blood gases in patients with severe acute heart failure has not been established.
Objective:
To assess the correlation between arterial and peripheral venous blood gases together with pulse-oximetry (SpO2), as well as to estimate arterial values from venous samples in the first hours upon admission of patients with acute cardiogenic pulmonary oedema.
Methods:
Simultaneous venous and arterial blood samples were extracted on admission and over the next 1, 2, 3, 4, and 10 hours. SpO2 was also registered at the same intervals.
Results:
A total of 178 pairs of samples were obtained from 34 consecutive patients with acute cardiogenic pulmonary oedema. Arterial and venous blood gases followed a parallel course in the first hours, showing high correlation rates at all time intervals. Venous samples underestimated pH (mean difference −0.028) and overestimated CO2 (+5.1 mmHg) and bicarbonate (+1 mEq/l). Conversely, SpO2 tended to underestimate SaO2 (mean±SD: 93.1±9.1 vs. 94.2±8.4). Applying simple mathematical formulae based on these differences, arterial values were empirically calculated from venous samples, showing acceptable agreement in the Bland−Altman test. Likewise, a venous pH <7.32, pCO2 >51.3 mmHg, and bicarbonate <22.8 mEq/l could fairly identify arterial acidosis, either respiratory or metabolic, with a test accuracy of 92, 68, and 91%, respectively.
Conclusions:
In patients with cardiogenic pulmonary oedema, arterial blood gas disturbances may be estimated from peripheral venous samples. By monitoring SpO2 simultaneously, arterial punctures could often be avoided.
doi:10.1177/2048872612457087
PMCID: PMC3760566  PMID: 24062917
Acute heart failure; arterial blood gases; pulmonary oedema; oxygen saturation; venous blood gases
24.  Effect of equivalent doses of fentanyl, sufentanil, and remifentanil on the incidence and severity of cough in patients undergoing abdominal surgery: A prospective, randomized, double-blind study 
Background: Fentanyl congeners have been found to induce cough during induction of general anesthesia. Studies of fentanyl and sufentanil have found incidence rates of 28% to 65% and 15%, respectively. However, no study has assessed the occurrence of cough induced by remifentanil.
Objective: The aim of this study was to assess the effect of equivalent doses of fentanyl, sufentanil, and remifentanil on cough.
Methods: Patients rated American Society of Anesthesiologists class I or II of either sex, aged 18 to 60 years, who were scheduled for elective abdominal surgery with general anesthesia were randomly and equally assigned to 3 groups using a computer-generated table of random numbers. The patients received equivalent doses of fentanyl 2 μg/kg, sufentanil 0.2 μg/kg, or remifentanil 2 μg/kg via IV push. Vital signs (systolic blood pressure [SBP], heart rate [HR], and oxygen saturation via pulse oximetry [SpO2]) and the occurrence and severity of cough were recorded for 2 minutes after drug administration by an anesthesiologist who was blinded to the drug treatment. The severity of cough was graded as none (0), mild (1–2), moderate (3–5), or severe (>5).
Results: A total of 315 Chinese patients (197 women, 118 men; mean [SD] age, 37.9 [10.4] years) were approached for enrollment and assigned to 3 groups of 105 patients each; all patients completed the study protocol. The 3 treatment groups were similar in terms of demographic characteristics and type of abdominal surgery. The incidence of cough was significantly greater in the remifentanil group (57 [54.3%] patients) than in the fentanyl group (35 [33.3%]; P < 0.01) or the sufentanil group (32 [30.5%]; P < 0.01). The severity of cough was significantly greater in the remifentanil group (severe, moderate, mild, none: 24, 7, 26, 48) than in the fentanyl (7, 9, 19, 70; P < 0.01) or sufentanil group (4, 2, 26, 73; P < 0.01). In all 3 groups, when the patients coughed, significant increases were observed in their SBP (128 [12]–139 [16] mm Hg; P < 0.01) and HR (74 [10]–87 [16] beats/min; P < 0.01). Within 2 minutes after drug administration, 62 patients (59%) in the remifentanil group experienced hypoxemia (SpO2 <90%) necessitating manually assisted mask ventilation, while no patients experienced hypoxemia in the fentanyl or sufentanil group. Three patients (2.9%) in the remifentanil group experienced muscle rigidity and deterioration of SBP, HR, and SpO2. No other adverse events were recorded.
Cunclusion: Remifentanil was associated with a significantly greater incidence and severity of cough than equivalent doses of fentanyl or sufentanil. Fentanyl and sufentanil appeared comparable in these Chinese patients undergoing abdominal surgery.
doi:10.1016/j.curtheres.2008.12.002
PMCID: PMC3969975  PMID: 24692822
cough; incidence; severity; fentanyl; sufentanil; remifentanil
25.  Ambulatory pulse oximetry monitoring in Japanese COPD outpatients not receiving oxygen therapy 
Background
It remains unknown whether desaturation profiles during daily living are associated with prognosis in patients with chronic obstructive pulmonary disease (COPD). Point measurements of resting oxygen saturation by pulse oximetry (SpO2) and partial pressure of arterial oxygen (PaO2) are not sufficient for assessment of desaturation during activities of daily living. A small number of studies continuously monitored oxygen saturation throughout the day during activities of daily living in stable COPD patients. This study aims to analyse the frequency of desaturation in COPD outpatients, and investigate whether the desaturation profile predicts the risk of exacerbation.
Methods
We studied stable COPD outpatients not receiving supplemental oxygen therapy. Baseline assessments included clinical assessment, respiratory function testing, arterial blood gas analysis, body mass index, and the COPD Assessment Test (CAT). Patients underwent 24-hour ambulatory monitoring of SpO2 during activities of daily living. Exacerbations of COPD and death from any cause were recorded.
Results
Fifty-one patients were enrolled in the study, including 12 current smokers who were excluded from the analyses in case high serum carboxyhaemoglobin concentrations resulted in inaccurately high SpO2 readings. The mean percent predicted forced expiratory volume in one second (%FEV1) was 50.9%. The mean proportion of SpO2 values below 90% was 3.0% during the day and 7.4% during the night. There were no daytime desaturators, defined as ≥ 30% of daytime SpO2 values below 90%. Twenty-one exacerbations occurred in 13 patients during the mean follow-up period of 26.4 months. Univariate and multivariate Cox proportional hazards analyses did not detect any significant factors associated with exacerbation.
Conclusions
Our 24-hour ambulatory oximetry monitoring provided precise data regarding the desaturation profiles of COPD outpatients. Both daytime and nighttime desaturations were infrequent. The proportion of ambulatory SpO2 values below 90% was not a significant predictor of exacerbation.
doi:10.1186/2049-6958-9-24
PMCID: PMC4021057  PMID: 24739130
Activities of daily living; Chronic obstructive pulmonary disease (COPD); Desaturator; Exacerbation; Outpatients; Pulse oximetry

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