Patients with Chronic Paralytic/Restrictive Ventilatory Dysfunction (5)
The untoward effects of OSAS appear to result primarily from dSaOjj. Chronic intermittent catecholamine release associated with periods of hypoxia and chronic sympathetic stimulation may play a role in the apparent increased incidence of systemic hypertension in OSAS. Its incidence was 58 percent in four studies of a total of 461 patients. The adverse effects of nocturnal dSa02 and systemic hypoxemia on the heart have been recognized since 1933. Barach et al found that angina could be produced in cardiac patients by causing a decrease in Sa02 below 85 percent by inhalation of 10 percent oxygen.
The acute hypoxic pressor response begins within seconds. Graded decreases in alveolar oxygen partial pressures produce similar increases in pulmonary vascular resistance with a threshold for vasoconstriction at 60 mm Hg. This corresponds to an Sa02 of approximately 90 percent at pH 7.40 and an Sa02 of approximately 85 percent at pH 7.20. Right ventricular volume overload, decreased cardiac output, sudden episodes of right ventricular hypotension, and life-threatening arrhythmias may follow. buy yasmin online
During obstructive apnea, the Sa02 drops off from a flat baseline and reaches a nadir, at which point the first apnea breaking breath results in rapid recovery of Sa02 to the original baseline. The abrupt recovery takes place in less than 12 s.