Anesthesia and analgesia
-
Anesthesia and analgesia · Sep 1993
Preanesthetic skin-surface warming reduces redistribution hypothermia caused by epidural block.
Redistribution of heat from the core to the cool peripheral compartments of the body causes hypothermia during epidural anesthesia. Diminishing the temperature gradient between the core and peripheral tissues by warming the body via the skin before anesthesia should prevent this hypothermia. We measured core temperature, skin temperatures, and cutaneous heat loss in seven volunteers who received two lidocaine epidural injections during a single study day. ⋯ Shivering was less after prewarming. We conclude that prewarming decreases redistribution hypothermia caused by epidural block. These results support the hypothesis that redistribution of heat within the body, not heat loss, is the most important etiology of hypothermia from epidural anesthesia.
-
Anesthesia and analgesia · Sep 1993
Chronic alcoholism increases the induction dose of propofol in humans.
The doses of propofol that produce loss of consciousness were investigated in 26 patients with chronic alcoholism and in 20 patients with a history of small alcoholic intake undergoing ear, nose, and throat surgery under general anesthesia. Last ethanol consumption by the alcoholics was 24 h preoperatively, as they had no access to alcohol when admitted to the hospital. Propofol was infused at a rate of 1200 mL/h (200 mg/min). ⋯ The dose of propofol required for dropping the syringe was significantly higher in the alcoholic group, 4.2 +/- 1.02 mg/kg versus 3.2 +/- 0.75 mg/kg in the control group (P < 0.01). The two groups did not differ significantly regarding the propofol blood concentrations at loss of consciousness, or the frequency of response or no response to painful stimulus. These findings suggest that the doses of propofol required to induce anesthesia in chronic alcoholic patients are more than in patients who drink socially.
-
Anesthesia and analgesia · Sep 1993
Selecting ventilator settings according to variables derived from the quasi-static pressure/volume relationship in patients with acute lung injury.
Knowledge of the pressure/volume (P/V) relationship of the lung may allow selection of tidal volume and positive end-expiratory pressure (PEEP) to optimize gas exchange without adversely affecting lung function or hemodynamics. Ten patients with acute lung injury were stabilized on controlled mechanical ventilation, based on conventional practice, using criteria from arterial blood gas data. The P/V relationship was determined under quasi-static conditions (end-expiratory and end-inspiratory, no flow periods > 0.8 s) during mechanical ventilation with an automated procedure that changed PEEP in a stepwise fashion. ⋯ Intrapulmonary shunt decreased from 0.28 +/- 0.08 (baseline) to 0.14 +/- 0.05 (12 h) (P < 0.001). Hemodynamic variables did not change. Our data suggest that using variables derived from a quasi-static P/V loop during mechanical ventilation under muscle paralysis is clinically superior compared to blood gas criteria for titration of ventilator settings.