Journal of critical care
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Cytokines released in response to stress may have a profound impact on circulatory stability. There is no information on the effect of general anesthesia alone on plasma cytokine levels and little information on cytokine release following surgery. Plasma cytokine levels and hemodynamic parameters were measured during anesthesia and abdominal surgery under sterile and nonpyrogenic conditions in seven pigs anesthetized with ketamine and pentobarbital. ⋯ Heart rate was unchanged during the experiment, and central venous pressure decreased after endotoxin (P < .05). There were no increases in TNF or IL-6 (using a low sensitivity assay) with anesthesia alone or following IM with shock, but both increased after endotoxin administration (P < .05); using a high sensitivity assay, IL-6 did not change during anesthesia alone but did increase fivefold following IM with shock (P < .05) and 50-fold following endotoxin administration (P < .05). We conclude that in a porcine model under sterile and nonpyrogenic conditions, prolonged anesthesia does not increase plasma cytokine levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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Journal of critical care · Jun 1993
Cardiopulmonary responses to continuous positive airway pressure in acute asthma.
The effects of nasal continuous positive airway pressure (CPAP) on expiratory flow, arterial blood gas tensions, cardiovascular status, and dyspnea were studied in 21 patients with acute asthma. Therapy consisted of the following CPAP sequence: 30 minutes at 5 cm H2O, 20 minutes at 0 cm H2O, 30 minutes at 7.5 cm H2O, and 20 minutes at 0 cm H2O. Six control patients were fitted with a CPAP mask but given no positive-pressure therapy. ⋯ These levels of CPAP were tolerated without deleterious side effects. In comparison, the control group showed no change in heart rate, respiratory rate, or breathlessness score during the study period. These data show that application of CPAP in acute asthma reduces respiratory rate and dyspnea with no untoward effects on gas exchange, expiratory airflow, or hemodynamics.
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Journal of critical care · Jun 1993
Comparative StudyPositive end-expiratory pressure increases capillary pressure relative to wedge pressure in the closed and open chest.
The pulmonary arterial wedge pressure is used as a measure of left atrial pressure and frequently as an estimate of pulmonary capillary pressure. The arterial occlusion concept has recently been used to derive a pressure that is thought to be more representative of capillary pressure (Pcap) than wedge pressure (Pw). The object of this study was to measure the arterial occlusion Pcap at different positive end-expiratory pressure (PEEP) levels and to compare it with Pw. ⋯ Increasing PEEP between 0 to 15 mm Hg caused a gradual decline in cardiac output in the closed and open chest conditions. Despite this decline, all three pressures (Pa, Pcap, and Pw) rose gradually in the closed chest. However, in the open chest, increasing PEEP from 0 to 4.7 mm Hg had no effect on the pressures, but between 4.7 and 13.4 mm Hg of PEEP, Pa and Pcap increased markedly with minimal change in Pw.(ABSTRACT TRUNCATED AT 250 WORDS)
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Journal of critical care · Jun 1993
Systemic oxygen extraction can be improved during repeated episodes of cardiac tamponade.
We used a tamponade model to study the relationship between oxygen uptake (VO2) and oxygen delivery (DO2) during successive, reversible decreases in blood flow. In 7 pentobarbital-anesthetized and mechanically ventilated dogs, a catheter was introduced via a left thoracotomy into the pericardium to inject and to withdraw saline. Each experiment consisted of three steps. ⋯ There was no significant difference in VO2 at DO2crit for the three steps. Hence, critical oxygen extraction ratio (ERO2crit) increased from 60% +/- 12% in step 1 to 64% +/- 11% in step 2 (not significant) and to 73% +/- 12% in step 3 (P < .01). The VO2/DO2 dependency slope was also steeper in step 3 than in step 1 (0.77 +/- 0.31 v 0.54 +/- 0.20, P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)