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Br J Anaesth. 2005 Nov;95(5):706-9. Epub 2005 Sep 2.

Pre-oxygenation in the obese patient: effects of position on tolerance to apnoea.

Author information

1
Departamento de Anestesiología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Chile. falterma@med.puc.cl

Abstract

BACKGROUND:

In obese patients, reduced functional residual capacity exacerbated by supine position might decrease the effectiveness of pre-oxygenation and the tolerance to apnoea. The aim of this study was to compare the effect of body posture during pre-oxygenation, sitting or supine, on its effectiveness in obese patients.

METHODS:

Forty obese patients (BMI > or =35 kg m(-2)) undergoing surgery with general anaesthesia were randomly assigned to one of two groups: Group 1 (sitting, n=20) or Group 2 (supine, n=20). In the predetermined body position, pre-oxygenation was achieved with eight deep breaths within 60 s and an oxygen flow of 10 litre min(-1). After rapid sequence induction of anaesthesia in decubitus position, the trachea was intubated and the patient was left apneic and disconnected from the anaesthesia circuit until Sp(o2) decreased to 90%. The time taken for desaturation to 90% from the end of induction of anaesthesia was recorded. Arterial blood oxygen tension was measured before (baseline) and after pre-oxygenation. Values were compared with two-way anova and unpaired Student's t-test.

RESULTS:

Oxygen and carbon dioxide tensions were similar between groups, both at baseline and after pre-oxygenation. However, the mean time to desaturation to 90% was significantly longer in the sitting group compared with the supine group [mean (SD): 214 (28) vs 162 (38) s, P<0.05].

CONCLUSIONS:

Pre-oxygenation in sitting position significantly extends the tolerance to apnoea in obese patients when compared with the supine position.

PMID:
16143575
DOI:
10.1093/bja/aei231
[Indexed for MEDLINE]
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