Validation of Pulse Oximetry During Progressive Normobaric Hypoxia Utilizing a Portable Chamber

Kolb, Jon C.; Farran, Peter R.; Norris, Stephen R.; Smith, David C.; Mester, Joachim

doi:10.1139/h04-001

Cited by 24 publications

(15 citation statements)

References 26 publications

(29 reference statements)

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“…Currently, there are no studies that determine [16], a frequent situation in this population [11][12][13]. The main aim of the present study was to determine whether altered blood CO 2 levels can change the existing relationship between Sa,O 2 and Sp,O 2 .…”

mentioning

confidence: 90%

Accuracy and reliability of pulse oximetry at different arterial carbon dioxide pressure levels

Muñoz¹,

Sampol²,

Ríos³

et al. 2008

European Respiratory Journal

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The present study aimed to assess whether arterial carbon dioxide pressure (Pa,CO 2 ) has an impact on agreement between oxygen saturation measured with pulse oximetry (Sp,O 2 ) or arterial blood gas co-oximetry (Sa,O 2 ).Sa,O 2 and Sp,O 2 determinations were obtained simultaneously from 846 patients under assessment for long-term home oxygen therapy in a specialised outpatient clinic. Both measurements were taken with patients seated and breathing room air.Agreement between Sa,O 2 and Sp,O 2 results was analysed by the Bland-Altman method and the Lin concordance coefficient. In addition, potential interactions of arterial oxygen tension (Pa,O 2 ) or Pa,CO 2 on agreement were analysed by adjusted multivariate analysis.Upon comparison of Sa,O 2 and Sp,O 2 results, the Bland-Altman technique yielded a bias (95% confidence interval (CI)) of -1.24 (-6.86-4.38) and -1.32 (-7.78-5.15) when Pa,CO 2 .48 mmHg (6.39 kPa) or Pa,O 2 ,54 mmHg (7.20 kPa), respectively. Estimate by Lin's coefficient (95% CI) in these cases was 0.88 (0.85-0.90) and 0.81 (0.77-0.85). Adjusted multivariate analysis, performed to assess the impact of pH, Pa,O 2 , Pa,CO 2 and bicarbonate on bias, showed that Pa,O 2 , Pa,CO 2 and their interaction terms were the most important predictors of the bias (standardised estimates of -0.54, -0.94, and 0.85, respectively). The effect of pH, although statistically significant, was small, and bicarbonate had no significant effect.Arterial carbon dioxide pressure status can contribute to impaired agreement between arterial oxygen saturation and arterial oxygen saturation measured with pulse oximetry, particularly in patients with hypercapnia.

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mentioning

confidence: 90%

Accuracy and reliability of pulse oximetry at different arterial carbon dioxide pressure levels

Muñoz¹,

Sampol²,

Ríos³

et al. 2008

European Respiratory Journal

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“…However, saturation is an indicator of oxygen delivery and does not necessarily reflect gas exchange (Dempsey and Wagner 1999). Also, saturation was measured indirectly with pulse oximetry, and validity of this method has been shown to decrease slightly when S a O 2 < 85% (Kolb et al 2004). Our results are contrary to recent findings by Zavorsky and colleagues who showed a mild increase in pulmonary oedema following intense normoxic exercise in women (Zavorsky et al 2006a) but no resultant impairment in gas exchange (Zavorsky et al 2006b).…”

Section: Pre-exercisementioning

confidence: 99%

Intense hypoxic cycle exercise does not alter lung density in competitive male cyclists

et al. 2007

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We tested the hypothesis that intense short duration hypoxic exercise would result in an increase in extravascular lung water (EVLW), as evidenced by an increase in lung density. Using computed tomography (CT), baseline lung density was obtained in eight highly trained male cyclists (mean +/- SD: age = 28 +/- 8 years; height = 180 +/- 9 cm; mass = 71.6 +/- 8.2 kg; VO2max= 65.0 +/- 5.2 ml kg min(-1)). Subjects then completed an intense hypoxic exercise challenge on a cycle ergometer and metabolic data, HR and %S(p)O2 were recorded throughout. While breathing 15% O2, subjects performed five 3 km cycling intervals (mean power, 286 +/- 20 W; HR = 91 +/- 4% HRmax) separated by 5 min of recovery. From a resting hypoxic S(p)O2 of 92 +/- 4%, subjects further desaturated during exercise to 76 +/- 3%. CT scans were repeated 76 +/- 10 min (range 63-88 min) following the completion of exercise. There was no change in lung density from pre (0.18 +/- 0.02 g ml(-1)) to post-exercise (0.18 +/- 0.04 g ml(-1)). The substantial reduction in S(p)O2 may be explained by a number of potential mechanisms, including decreased pulmonary diffusion capacity, alveolar hypoventilation, reduced red cell transit time, ventilation/perfusion inequality or a temperature and pH induced rightward-shift in the oxyhaemoglobin dissociation curve. Alternatively, the integrity of the blood gas barrier may have been disrupted without any measurable increase in lung density.

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“…Overall differences were small and pulse oximetry measurement as well as lung function measurement has a certain bias [30,31]. Such bias would affect both study groups, but cannot be completely ignored.…”

Section: Discussionmentioning

confidence: 99%

Short term non-invasive ventilation post-surgery improves arterial blood-gases in obese subjects compared to supplemental oxygen delivery - a randomized controlled trial

et al. 2011

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BackgroundIn the immediate postoperative period, obese patients are more likely to exhibit hypoxaemia due to atelectasis and impaired respiratory mechanics, changes which can be attenuated by non-invasive ventilation (NIV). The aim of the study was to evaluate the duration of any effects of early initiation of short term pressure support NIV vs. traditional oxygen delivery via venturi mask in obese patients during their stay in the PACU.MethodsAfter ethics committee approval and informed consent, we prospectively studied 60 obese patients (BMI 30-45) undergoing minor peripheral surgery. Half were randomly assigned to receive short term NIV during their PACU stay, while the others received routine treatment (supplemental oxygen via venturi mask). Premedication, general anaesthesia and respiratory settings were standardized. We measured arterial oxygen saturation by pulse oximetry and blood gas analysis on air breathing. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 1 h, 2 h, 6 h and 24 h after extubation, with the patient supine, in a 30 degrees head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t-test analysis. Statistical significance was considered to be P < 0.05.ResultsThere were no differences at the first assessment. During the PACU stay, pulmonary function in the NIV group was significantly better than in the controls (p < 0.0001). Blood gases and the alveolar to arterial oxygen partial pressure difference were also better (p < 0.03), but with the addition that overall improvements are of questionable clinical relevance. These effects persisted for at least 24 hours after surgery (p < 0.05).ConclusionEarly initiation of short term NIV during in the PACU promotes more rapid recovery of postoperative lung function and oxygenation in the obese. The effect lasted 24 hours after discontinuation of NIV. Patient selection is necessary in order to establish clinically relevant improvements.Trial Registration#DRKS00000751; http://www.germanctr.de

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Validation of Pulse Oximetry During Progressive Normobaric Hypoxia Utilizing a Portable Chamber

Cited by 24 publications

References 26 publications

Accuracy and reliability of pulse oximetry at different arterial carbon dioxide pressure levels

Accuracy and reliability of pulse oximetry at different arterial carbon dioxide pressure levels

Intense hypoxic cycle exercise does not alter lung density in competitive male cyclists

Short term non-invasive ventilation post-surgery improves arterial blood-gases in obese subjects compared to supplemental oxygen delivery - a randomized controlled trial

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