BACKGROUND Daytime hypercapnia is common in morbidly obese patients with obstructive sleep apnea and is associated with serious complications. Our objective was to quantify the effect of adherence with positive airway pressure on hypercapnia and hypoxia in these patients. METHODS We performed a retrospective cohort study of 75 patients using a multivariable general linear model analysis to id...

Previous studies have reported mixed results when correlating etCO2 and PaCO2 in mechanically ventilated patients with underlying respiratory disease. However, the utility and accuracy of capnography in nonintubated patients, without chronic pulmonary disease, has received little attention. We studied 25 nonintubated surgical patients to (1) examine the correlation between PaCO2 and etCO2 and (...

Our aim was to quantify the end-tidal-to-arterial gas gradients for O2 (PET-PaO2) and CO2 (Pa-PETCO2) during a CO2 reactivity test to determine their influence on the cerebrovascular (CVR) and ventilatory (HCVR) response in subjects with (PFO+, n = 8) and without (PFO-, n = 7) a patent foramen ovale (PFO). We hypothesized that 1) the Pa-PETCO2 would be greater in hypoxia compared with normoxia,...

BACKGROUND Measuring and monitoring end-tidal carbon dioxide (PETCO2) is an important aspect of caring for critically ill patients. The 2 methods used for PETCO2 measurement are the mainstream and sidestream methods. OBJECTIVE To assess the agreement between PETCO2 measurements performed by mainstream and sidestream methods with the PaCO2 values. METHODS This was a prospective observational...

OBJECTIVE To assess the accuracy of measurements of end tidal carbon dioxide (CO2) during neonatal transport compared with arterial and transcutaneous measurements. DESIGN Paired end tidal and transcutaneous CO2 recordings were taken frequently during road transport of 21 ventilated neonates. The first paired CO2 values were compared with an arterial blood gas. The differences between arteria...

Cerebrovascular reactivity to CO2 inhalation and voluntary hyperventilation was studied in seven normotensive subjects and nine hypertensive patients without clinical or angiographical signs of arteriosclerosis. Cerebral blood flow (CBF) was measured by the intracarotid 133Xe clearance method and calculated as the initial slope index. Three to five CBF measurements were made in each patient in ...

Cerebral blood flow (CBF) was determined in the rat under 70% nitrous oxide anesthesia and pentobarbital anesthesia. The application of the Fick principle technique of Kety et al. was modified utilizing 133Xe infused intravenously steadily for 30 seconds, at which time the animal was decapitated and the head frozen in liquid nitrogen. A prior femoral artery to femoral vein shunt was led through...

INTRODUCTION Problems associated with the standard apnea test relate to overshooting or undershooting the target PaCO2, potentially compromising the viability of organs for transplantation or invalidating the test. MATERIALS AND METHODS In 60 adult patients, the authors used an alternative method using exogenously administered CO2 and measurement of end-tidal CO2. RESULTS All patients achie...