Intensive care medicine
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Intensive care medicine · Jan 1987
Suppression of spontaneous breathing during high-frequency jet ventilation. Separate effects of lung volume and jet frequency.
The effect of ventilatory frequency of high-frequency jet ventilation (HFJV) from 1 to 5 Hz, apart from changes in thoracic volume, on spontaneous breathing activity was studied in Yorkshire piglets under pentobarbital anesthesia. The highest PaCO2 at which the animals did not breathe against the ventilator (apnea point) was established either by changing minute volume of ventilation or by adding CO2 to the respiratory gas. The higher the apnea point, the higher the suppression of spontaneous breathing activity was assumed to be. ⋯ When thoracic volume was kept constant in this way a constant tidal volume at increasing jet frequencies resulted in only a slight increase in suppression of spontaneous breathing. We conclude that the increase in lung volume is a major factor in suppressing central respiratory activity during HFJV. Jet frequency by itself might be an additional suppressive factor.(ABSTRACT TRUNCATED AT 250 WORDS)
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Intensive care medicine · Jan 1987
Comparative StudyRelation of oxygen transport patterns to the pathophysiology and therapy of shock states.
Descriptions of the sequence of hemodynamic and oxygen transport events have characterized the various types of shock syndromes and have shown that reduced VO2 is the earliest pathophysiologic event; it precedes the initial hypotensive crisis. Reduced or inadequate VO2, produced by low flow, by maldistribution of flow, and by increased metabolic demand is the primary pathogenic event that produces the shock state as well as the regulatory mechanism that stimulates compensatory reactions including increases in heart rate, myocardial contractility, cardiac output and minute ventilation. Sequential hemodynamic and oxygen transport patterns are related to the degree of the shock state and its outcome; the patterns of survivors and nonsurvivors can be predicted from these patterns by multivariate analyses. ⋯ This approach emphasizes aggressive fluid management in tacit acknowledgement that unrecognizes hypovolemia, delay in treatment of hypovolemia or inadequate volume therapy all lead to low VO2 which is the primary precipitating event in most patients with postoperative, hemorrhagic, traumatic and septic shock. The essence of this plan is to maintain prophylactically the patient in an optimal hemodynamic state that does not allow him to develop tissue hypoxia from blood volume, hemodynamic and oxygen transport deficits. However, episodes of reduced CI, DO2 and VO2 often occur intraoperatively with little or no hypotension or with hypotension which is treated by administration of ephedrine or other vasopressors.
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Intensive care medicine · Jan 1987
Retracted PublicationInfluence of cardiac output on thermal-dye extravascular lung water (EVLW) in cardiac patients.
The influence of varying cardiac output (CO) on thermal-dye extravascular lung water (EVLW) was investigated in a total of 40 cardiac surgery patients before the onset of the operation. EVLW was measured by means of the double indicator dilution technique with indocyanine green as the non-diffusible indicator and a microprocessed lung water computer 15 min and 30 min after change of CO. CO was varied from -45% to +70% of the baseline value by nifedipine infusion (CO increases, n = 20) or halothane application (CO decreases, n = 20), respectively. ⋯ CO estimation was comparable for both methods used. Regression analysis revealed no relationship between CO and EVLW as well as between EVLW and various hemodynamic parameters. We conclude that thermal-dye technique for estimation of EVLW may be accurate in spite of changing cardiac output over a wide range.