The accuracy of pulse oximetry in the emergency department
ABSTRACT The objective of this retrospective study was to identify factors affecting the accuracy of pulse oximetry in the ED. Over a 3-year period, 664 consecutive emergency department (ED) patients had simultaneous arterial blood gas (ABG) and pulse oximeter readings taken. Pulse oximeter saturations (SpO2) were compared with ABG CO-oximeter saturations (SaO2) for accuracy. Multiple variables including age, sex, hemoglobin, bicarbonate, pH, and carboxyhemoglobin (COHb) were analyzed to see if they affected SpO2 accuracy. ROC curves were used to determine the best pulse oximeter threshold for detecting hypoxia. Using multivariate analysis, COHb was the only statistically significant factor affecting the accuracy of pulse oximetry. In patients with COHb <2%, SpO2 overestimated SaO2 by more than 4% in 8.4% of cases. In patients with COHb > or = 2%, SpO2 overestimated SaO2 by more than 4% in 35% of cases. The best pulse oximetry threshold for detecting hypoxia is 92%. At this threshold, if COHb is <2%, pulse oximetry has a sensitivity of 0.92 and specificity of 0.90. If COHb is > or =2%, sensitivity is 0.74 and specificity is 0.84. For patients likely to have a COHb < 2, pulse oximetry is an effective screening tool for detecting hypoxia. However, more caution must be exercised when using pulse oximetry in patients likely to have a COHb > or = 2%.
- SourceAvailable from: Sonnia M López-Silva[Show abstract] [Hide abstract]
ABSTRACT: El principal problema al monitorizar la frecuencia cardiaca mediante fotopletismografía durante el ejercicio son los artefactos por movimiento. Hemos registrado fotopletismogramas por transmisión en atletas durante pruebas de esfuerzo máximo en tapiz rodante, con un nuevo sistema sensor basado en tres diodos láser con emisiones en longitudes de onda del infrarrojo cercano. Los valores de frecuencia cardiaca obtenidos con un algoritmo de procesamiento desarrollado para este fin, coinciden los de electrocardiografía.XXIII Congreso Anual de la Sociedad Española de Ingeniería Biomédica (CASEIB 2005), Madrid; 07/2005
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ABSTRACT: There is little evidence that the guideline-recommended oxygen saturation of 92% is the best cut-off point for detecting hypoxemia in COPD exacerbations. To detect and validate pulse oximetry oxygen saturation cut-off values likely to detect hypoxemia in patients with aeCOPD, to explore the correlation between oxygen saturation measured by pulse oximetry and hypoxemia or hypercapnic respiratory failure. Cross-sectional study nested in the IRYSS-COPD study with 2,181 episodes of aeCOPD recruited between 2008 and 2010 in 16 hospitals belonging to the Spanish Public Health System. Data collected include determination of oxygen saturation by pulse oximetry upon arrival in the emergency department (ED), first arterial blood gasometry values, sociodemographic information, background medical history and clinical variables upon ED arrival. Logistic regression models were performed using as the dependent variables hypoxemia (PaO2 < 60 mmHg) and hypercapnic respiratory failure (PaO2 < 60 mmHg and PaCO2 > 45). Optimal cut-off points were calculated. The correlation coefficient between oxygen saturation and pO2 measured by arterial blood gasometry was 0.89. The area under the curve (AUC) for the hypoxemia model was 0.97 (0.96-0.98) and the optimal cut-off point for hypoxemia was an oxygen saturation of 90%. The AUC for hypercapnic respiratory failure was 0.90 (0.87-0.92) and the optimal cut-off point was an oxygen saturation of 88%. Our results support current recommendations for ordering blood gasometry based on pulse oximetry oxygen saturation cut-offs for hypoxemia. We also provide easy to use formulae to calculate pO2 from oxygen saturation measured by pulse oximetry.COPD Journal of Chronic Obstructive Pulmonary Disease 03/2015; DOI:10.3109/15412555.2014.995291 · 2.62 Impact Factor
- Indian Journal of Critical Care Medicine 01/2015; 19(4):203. DOI:10.4103/0972-5229.154549