Archive for the ‘Alveolar Hypoventilation’ Category


The central clinical features of this case include dysauto-nomia, parkinsonism, and abnormalities in respiratory control. Unlike previous reports, in this patient, the medulla was morphologically intact. Instead, there was a widespread neuropathy, as well as the classic pathologic findings of Shy-Drager. The moderate abnormalities in respiratory mechanics do not, by themselves, explain the presence of hypercapnic respiratory failure. Although there was evidence of phrenic and intercostal nerve pathologic conditions, the preservation of vital capacity with changes in posture, the lack of paradoxic thoracoabdominal movements, and the presence of substantial maximal inspiratory and expiratory pressures are indications of neuromuscular apparatus sufficient to provide an adequate minute ventilation gas exchange. (more…)

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  • Pathophysiologic Findings in a Patient with Shy-Drager and Alveolar Hypoventilation Syndromes: Pulmonary centrilobular emphysemaAverage inspiratory time, average cycle length, and the coefficient of variation (SD/M) for respiratory timing increased from wakefulness to sleep. In contrast, the coefficient of variation for heart rate was similar during wakefulness and sleep. There were no significant changes in respiratory pattern with medroxyprogesterone acetate (120 mg, qd for three weeks) or with acetazolamide, administered once (250 mg intravenously). The patient received positive pressure ventilatory support only during sleep. Two months after first evaluation, the patient was found pulseless, without blood pressure or respirations one-half hour before his customary bedtime. (more…)

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  • The patient exhibited no respiratory distress. However, while watching television, he seemed to “forget to breathe.” Pulmonary function testing performed through the tracheostomy showed a vital capacity of 1.75 L (50 percent of predicted), forced expiratory volume in one second of 1.1 L (45 percent), and a total lung capacity determined by helium dilution of 5.12 L (92 pecent). Arterial blood gas values during wakefulness showed a pH of 7.34, P02 of 72, and PCO2 of 62 on 30 percent FIo2. His chest roentgenogram showed an elevated right hemidiaphragm. Vital capacity in the supine posture was 1.65 L, unchanged from values in the upright posture (1.70 L). Percutaneous stimulation of the phrenic nerve produced a latency of 9.2 ms on the right and 11.0 ms on the left (normal: 9 to 10 ms.) Maximal inspiratory pressures at functional residual capacity were 85 cmH20 (82 percent), expiratory pressures at total lung capacity were 90 cmHsO (48 percent). Tests of hypercapnic responsiveness with rebreathing and hypoxic responsiveness by withdrawal from administration of 100 percent 02 were abnormally low or absent. Heart rate was unchanged during testing for ventilatory responsiveness. Breathholding time was greater than 60 seconds, and the test was halted when the oxygen saturation fell below 75 percent. (more…)

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  • Pathophysiologic Findings in a Patient with Shy-Drager and Alveolar Hypoventilation SyndromesRespiratory disturbances during wakefulness and sleep are common in patients with the Shy-Drager syndrome. The available pathologic studies describe lesions in the brainstem and conclude that these morphologic changes were responsible for the premorbid disturbances in respiratory control.- In this case, despite hypercapnic respiratory failure and apnea/hypoventilation during sleep, at autopsy there were no pontomedullary abnormalities.
    Case Report
    This hospitalized 73-year-old black man was evaluated nine months after he was admitted in respiratory failure. Two years prior to evaluation, he developed excessive daytime sleepiness, episodic shortness of breath, and confusion. Syncope and urinary frequency developed the next year. Nine months prior to evaluation, he was admitted for respiratory failure. A tracheostomy was performed because of obstructive apnea during sleep and hypercapnic respiratory failure. A transurethral resection of the prostate revealed an unsuspected adenocarcinoma of the prostate. The patient was unable to leave the hospital because of orthostatic hypotension. (more…)

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