ABSTRACT
To assess the accuracy of nasal capnography for the monitoring of ventilation in extubated morbidly obese patients, following bariatric surgery. prospective descriptive study. Post-anesthesia care unit. 25 consecutive morbidly obese patients admitted to the PACU after open bariatric surgery. Patients had a nasal cannula designed to administer oxygen [3 L/min] and to sample expired CO[2] by a coaxial catheter. Capnographic waveform, end-tidal CO[2] [ETCO[2]] and respiratory rate [RRd] were displayed by a capnometer [Datex-Ohmeda]. Arterial CO[2] pressure [PaCO[2]] was measured by blood gas analysis. Respiratory rate was measured by visual inspection of chest breathing motions [RRm]. Differences between PaCO[2] and ETCO[2] and between RRd and RRm were calculated for every simultaneous set of measurements. Bias, precision, limits of agreement [bias +/- 2 precisions] between PetCO[2] and PaCO[2] were respectively as follows: 3.1, 1.4, 0.3 to 5.9 mmHg with a Pearson correlation coefficient of 0.6 and a P value of 0.001. As for RRd v/s RRm the values were: 2, 0.5, 1 to 3 breaths per minute and 0.8 with the same P value for the Pearson coefficient. Limits of agreement between PaCO[2] and ETCO[2] pressure and between RRd and RRm are clinically acceptable. Nasal capnography is accurate for the monitoring of ventilation in extubated morbidly obese patients, following bariatric surgery