1/13. Acute respiratory alkalosis associated with low minute ventilation in a patient with severe hypothyroidism.PURPOSE: patients with severe hypothyroidism present unique challenges to anesthesiologists and demonstrate much increased perioperative risks. overall, they display increased sensitivity to anesthetics, higher incidence of perioperative cardiovascular morbidity, increased risks for postoperative ventilatory failure and other physiological derangements. The previously described physiological basis for the increased incidence of postoperative ventilatory failure in hypothyroid patients includes decreased central and peripheral ventilatory responses to hypercarbia and hypoxia, muscle weakness, depressed central respiratory drive, and resultant alveolar hypoventilation. These ventilatory failures are associated most frequently with severe hypoxia and carbon dioxide (CO2) retention. The purpose of this clinical report is to discuss an interesting and unique anesthetic presentation of a patient with severe hypothyroidism. CLINICAL FEATURES: We describe an unique presentation of ventilatory failure in a 58 yr old man with severe hypothyroidism. He had exceedingly low perioperative respiratory rate (3-4 bpm) and minute ventilation volume, and at the same time developed primary acute respiratory alkalosis and associated hypocarbia (P(ET)CO2 approximately 320-22 mmHg). CONCLUSION: Our patient's ventilatory failure was based on unacceptably low minute ventilation and respiratory rate that was unable to sustain adequate oxygenation. His profoundly lowered basal metabolic rate and decreased CO2 production, resulting probably from severe hypothyroidism, may have resulted in development of acute respiratory alkalosis in spite of concurrently diminished minute ventilation.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
2/13. Patient-ventilator interactions during volume-support ventilation: asynchrony and tidal volume instability--a report of three cases.During pressure-support ventilation, tidal volume (V(T)) can vary according to the level of the patient's respiratory effort and modifications of the thoraco-pulmonary mechanics. To keep V(T) as constant as possible, the Siemens Servo 300 ventilator proposes an original modification of pressure-support ventilation, called volume-support ventilation (VSV). VSV is a pressure-limited mode of ventilation that uses V(T) as a feedback control: the pressure support level is continuously adjusted to deliver a preset V(T). Thus, the ventilator adapts the inspiratory pressure level, breath by breath, to changes in the patient's inspiratory effort and the mechanical thoraco-pulmonary properties. The clinician sets V(T) and respiratory frequency, and the ventilator calculates a preset minute volume. It has been shown that ineffective respiratory efforts can occur during pressure-support ventilation.- - - - - - - - - - ranking = 11keywords = volume (Clic here for more details about this article) |
3/13. Embolization of hepatic hemangiomas in infants.A small number of cavernous liver hemangiomas in infants cause serious symptoms, requiring active treatment. We report two newborns with giant liver hemangiomas, treated by intra-arterial embolization. The babies presented at 2 - 8 days after birth with tachypnoea and cardiac dilation. A giant liver hemangioma located in the right liver lobe in one infant and in the left liver lobe in the other was found at ultrasonography and computed tomography. Dilated liver veins indicated abnormal shunting of the blood through the hemangiomas. Because of progress of symptoms superselective embolization of the arteries feeding the hemangiomas and arising from the celiac trunk was performed with a mixture of Lipoidol and Histoacryl. A decrease of tachypnoea and of heart volume was noted after embolization. In one infant surgery was necessary due to gastrointestinal bleeding. The intra-arterial embolization is a valuable method for the treatment of newborns with symptomatic cavernous liver hemangiomas.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
4/13. Upper airway dysfunction in olivopontocerebellar atrophy.We report the findings in a patient known to have olivopontocerebellar atrophy who developed respiratory distress, inspiratory stridor, and maximum inspiratory and expiratory flow volume loops. Treatment with carbidopa-levodopa gave symptomatic relief.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
5/13. A case of dirhythmic breathing.We describe a case of dirhythmic breathing in a 60-year-old man after neurosurgery. A large hemangioblastoma was removed from the cerebellum at the level of the fourth ventricle. The spirometric tracings showed two types of respiratory cycles: the rhythm. A was stable with a short inspiratory time; sometimes a second type of respiratory cycle, B, was present or erratically coupled with the A rhythm. It had very small tidal volume and mean inspiratory flow with phasic variations similar to those observed in Cheyne-Stokes breathing pattern.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
6/13. Vocal cord closure. A cause of upper airway obstruction during controlled ventilation.Studies of vocal cord function were undertaken in a quadriplegic patient requiring ventilatory assistance, and in 2 normal subjects during controlled ventilation in a tank-type respirator. When the patient and the normal subjects relaxed and made no conscious effort to assist the respirator, the vocal cords were observed to close during inspiration and a large pressure gradient (12 to 19 cm H2O) developed across the cords. When the subjects made a slight inspiratory effort ("assist" mode), the cords opened widely during inspiration. There were large increases in flow and tidal volume in the "assist" mode compared with passive ventilation. Measurements of transdiaphragmatic pressure and esophageal pressure showed that these variables did not increase with the slight assist. Thus, increase in ventilation during the "assist" mode appeared to be due to alleviation of inspiratory obstruction at the level of the vocal cords. The same phenomenon was observed in the patient during phrenic nerve pacing. A pacemaker was designed to be triggered by the electromyographic impulse from an accessory muscle of respiration. In this manner, vocal cord opening could be coordinated with the mechanical assist given by the phrenic nerve pacer.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
7/13. amyotrophic lateral sclerosis presenting with sleep hypopnea syndrome.Described is a 67-year-old man whose initial symptoms evoked an obesity-hypoventilation syndrome. polysomnography showed hypopneas associated with O2 desaturation episodes, and no apnea; maximal changes were noted during REM sleep. A few months later, in spite of marked weight loss, acute alveolar hypoventilation occurred and necessitated mechanical ventilatory support. tracheostomy was performed. The patient appeared to be dependent on nocturnal ventilatory assistance. Diaphragmatic paralysis was noted in addition to clinical and electrodiagnostic evidence of amyotrophic lateral sclerosis. While the patient was not ventilated, a nocturnal recording of SaO2 again revealed desaturation episodes partly corrected by O2 2 L/min administered through the tracheostomy tube. With volume-controlled ventilation, desaturations completely disappeared, although no oxygen enrichment of the air was provided. We speculate that sleep disorders with hypopneas and O2 desaturation episodes were the initial symptoms of amyotrophic lateral sclerosis. This leads us to suggest that nonspecific respiratory muscle fatigue frequently seen in COPD might be included in the hypothetic causes of nocturnal hypoxemia.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
8/13. The irregularly irregular pattern of respiratory dyskinesia.The respiratory pattern during wakefulness and sleep was characterized in a 70-year-old woman with respiratory dyskinesia. During wakefulness, both respiratory frequency and tidal volume exhibited an irregularly irregular pattern. In addition, wide fluctuations occurred in the position of the rib cage and abdomen at end expiration. A normal respiratory pattern appeared during non-REM and REM sleep.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
9/13. Dysfunction of small airways following pulmonary injury due to nitrogen dioxide.Serial physiologic studies were performed to characterize both the immediate and delayed effects of a single occupational exposure to nitrogen dioxide in a nonsmoker. During the initial acute stage of pulmonary edema, the abnormal static pressure-volume curve and decreased static compliance corresponded to a reduction in pulmonary volume. During the delayed acute stage, elastic recoil and properties of resistance to flow were normal, but dynamic compliance was reduced and dependent on respiratory frequency, and oxygen transport was abnormal during exercise, which is consistent with dysfunction of the small airways.- - - - - - - - - - ranking = 2keywords = volume (Clic here for more details about this article) |
10/13. Chronic ventilatory failure caused by abnormal respiratory pattern generation during sleep.A 67-yr-old man presented with a 4-yr history of chronic ventilatory failure in the absence of any restrictive or obstructive ventilatory defect. Detailed neurologic investigations were unremarkable, and the response of minute volume of ventilation to inhaled CO2 was normal. During sleep there was no evidence of upper airway obstruction, and minute volume of ventilation averaged 6.7 L/min, compared with 7.2 L/min during quiet wakefulness. However, sleep was associated with a rapid and shallow pattern of breathing, resulting in high dead space ventilation, inadequate alveolar ventilation, hypoxemia, and hypercapnia. Correction of the abnormal ventilatory pattern during sleep by diaphragmatic pacing abolished all features of chronic respiratory failure. The findings indicate that a disorder of respiratory pattern during sleep can produce chronic ventilatory failure, despite normal respiratory drive.- - - - - - - - - - ranking = 2keywords = volume (Clic here for more details about this article) |
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