The accuracy of pulse oximetry in emergency department patients with severe sepsis and septic shock: a retrospective cohort study

Wilson, Ben; Cowan, Hamish J; Lord, Jason; Zuege, Danny J.; Zygun, David

doi:10.1186/1471-227x-10-9

Cited by 115 publications

(95 citation statements)

References 26 publications

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“…With regard to S aO2 predictions, many studies in the literature have been focused on determining the expected differences between the actual S aO2 and the S pO2 values for ICU patients. The average differences between experimentally measured S aO2 values and S pO2 measurements are reported as 2.4-2.75 % with an SD of about 3 % [31][32][33]. The results of this study are in general agreement with these findings.…”

Section: Resultssupporting

confidence: 93%

A model-based decision support system for critiquing mechanical ventilation treatments

Tehrani

Abbasi

2012

J Clin Monit Comput

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A computerized system for critiquing mechanical ventilation treatments is presented that can be used as an aide to the intensivist. The presented system is based on the physiological model of the subject's respiratory system. It uses modified versions of previously developed models of adult and neonatal respiratory systems to simulate the effects of different ventilator treatments on the patient's blood gases. The physiological models that have been used for research and teaching purposes by many researchers in the field include lungs, body tissue, and the brain tissue. The lung volume is continuously time-varying and the effects of shunt in the lung, changes in cardiac output and cerebral blood flow, and the arterial transport delays are included in the system. Evaluation tests were done on adult and neonate patients with different diagnoses. In both groups combined, the differences between the arterial partial pressures of CO(2) predicted by the system and the experimental values were 1.86 ± 1.6 mmHg (mean ± SD), and the differences between the predicted arterial hemoglobin oxygen saturation values, S(aO2), and the experimental values measured by using pulse oximetry, S(pO2), were 0.032 ± 0.02 (mean ± SD). The proposed system has the potential to be used alone or in combination with other decision support systems to set ventilation parameters and optimize treatment for patients on mechanical ventilation.

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Section: Resultssupporting

confidence: 93%

A model-based decision support system for critiquing mechanical ventilation treatments

Tehrani

Abbasi

2012

J Clin Monit Comput

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“…The bias and 95% CI for limits of agreement in our whole population (2.5% and (Ϫ10.1,15.1)%) were also larger than those reported by most studies in non-hyperleukocytic subjects [24][25][26] but were probably negatively affected by samples with extreme WBC count. Indeed, the bias and 95% CI for limits of agreement that we observed in subjects with WBC count Ͻ 100 ϫ 10 9 /L (0.4% and (Ϫ7.9,8.6)%) are similar to those reported in studies in critically ill 27 and COPD 26 populations. Conversely, the bias and 95% CI for limits of agreement were 3.8% and (Ϫ10.3,18.0)% for WBC count Ͼ 100 ϫ 10 9 /L, whereas one of the largest studies on 102 general ICU subjects reported a bias of only 0.02% with 95% CI for limits of agreement of (Ϫ4.2,4.2)%.…”

Section: Discussionsupporting

confidence: 72%

Hypoxemia During Extreme Hyperleukocytosis: How Spurious?

Louw

Desai²,

Schneider³

et al. 2015

Respir Care

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BACKGROUND: Spurious hypoxemia has been described in case reports during extreme hyperleukocytosis and has led to recommendations for immediate cooling and analysis of arterial blood gases (ABGs). We sought to determine, in samples processed as recommended, the magnitude of spurious hypoxemia in acute leukemia subjects with hyperleukocytosis. METHODS: A retrospective chart review was conducted of all subjects admitted between 2003 and July 2014 for acute leukemia, who presented with white blood cell (WBC) count > 50 ؋ 10 9 cells/L and had ABGs performed. For each ABG, we collected P aO 2 , S aO 2 , simultaneous WBC count, and S pO 2 when available. Bland and Altman analysis was used to assess the agreement between S pO 2 and S aO 2 . RESULTS: One-hundred forty-six samples (from 45 subjects) were included, of which 57 samples (from 18 subjects) had data available for Bland and Altman analysis. Mean (S pO 2 ؊ S aO 2 ) was 2.5%, and 95% CI for limits of agreement between S pO 2 and S aO 2 was (؊10.1,15.1)%. The mean (S pO 2 -S aO 2 ) was significantly higher for WBC count > 100 ؋ 10 9 /L as compared with WBC count < 100 ؋ 10 9 /L (3.8% vs 0.4%, P ‫؍‬ .04), and the 95% CIs for limits of agreement were (؊10.3,18)% versus (؊7.9,8.6)%. S pO 2 and S aO 2 were poorly correlated (r 2 ‫؍‬ 0.19), whereas the difference (S pO 2 -S aO 2 ) was fairly correlated with WBC count (r 2 ‫؍‬ 0.44). Overall, 11 of 19 samples with WBC count > 150 ؋ 10 9 /L had P aO 2 < 55 mm Hg whereas S pO 2 was > 94%, the proportion being 5 of 62 samples for WBC count < 150 ؋ 10 9 /L (P < .001). Three subjects with WBC count > 150 ؋ 10 9 /L exhibited large S pO 2 to S aO 2 differences (10 -20%) before leukapheresis, which decreased to below 5% afterward. CONCLUSIONS: In subjects with acute leukemia and hyperleukocytosis, despite cooling and quickly analyzing the samples, we observed poor correlation and agreement between S pO 2 and S aO 2 , unacceptably low for WBC count > 100 ؋ 10 9 /L. Our results suggest that current guidelines may not totally prevent the diagnosis of spurious hypoxemia.

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“…The discrepancy between healthy volunteers examined during the empirical calibration process and patients is further accentuated in neonates 22. The deviation of SpO 2 from SaO 2 is even greater at saturations below 70%–80%,11,23–26 because ethical restrictions prevent manufacturers from reducing SaO 2 below 80% during the calibration process. The inaccuracy associated with the co-oximetry itself (upon which the calibration process is based) is an additional contributing factor to the error in SpO 2 measurement 17…”

Section: The Accuracy Of Pulse Oximetrymentioning

confidence: 99%

Pulse oximetry: fundamentals and technology update

Nitzan

Romem

Koppel

2014

MDER

301

252

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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.

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The accuracy of pulse oximetry in emergency department patients with severe sepsis and septic shock: a retrospective cohort study

Cited by 115 publications

References 26 publications

A model-based decision support system for critiquing mechanical ventilation treatments

A model-based decision support system for critiquing mechanical ventilation treatments

Hypoxemia During Extreme Hyperleukocytosis: How Spurious?

Pulse oximetry: fundamentals and technology update

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