Anesthesia and analgesia
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Anesthesia and analgesia · May 1995
Randomized Controlled Trial Clinical TrialArterial and jugular venous bulb blood propofol concentrations during induction of anesthesia.
The aim of this study was to show that blood propofol concentrations at loss of consciousness vary with the rate of administration. Eighteen patients were allocated to receive a propofol infusion at 6 or 12 mg.kg-1.h-1 (approximately 8 and 15 mg/min) for induction of anesthesia. Propofol concentrations were analyzed from simultaneous arterial and jugular bulb venous blood samples. ⋯ There were no significant differences between the groups in the area between the arterial and venous time concentration curves from start of infusion to loss of consciousness (3.14 and 3.05 micrograms.mL-1.min-1). This study confirms that a target blood concentration of propofol cannot be identified with loss of consciousness under nonsteady state conditions. Both arterial and venous blood propofol concentrations at loss of consciousness depend on the rate of administration.
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Anesthesia and analgesia · May 1995
The effect of graded hemorrhage and intravascular volume replacement on systolic pressure variation in humans during mechanical and spontaneous ventilation.
In dogs and humans, the magnitude of the variation in systolic pressure (SPV) over the respiratory cycle during mechanical ventilation appears to be inversely related to intravascular volume. Also reported to correlate with changes in volume status is delta down, the difference between systolic pressure at end-expiration and the lowest value during the respiratory cycle. These variables were examined during graded hemorrhage in eight anesthetized, mechanically ventilated subjects, and seven awake, spontaneously breathing subjects. ⋯ After hetastarch, both SPV and delta down were smaller than at baseline and may explain why the infusion of NS caused nonsignificant reductions in SPV and delta down. A SPV of 5 mm Hg or less, or a delta down of 2 mm Hg or less appeared to indicate minimal intravascular volume depletion. During spontaneous ventilation, delta down could not be determined accurately in several subjects, and SPV did not change in the appropriate direction in all cases of hemorrhage and volume infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · May 1995
Ventilatory effects, blood gas changes, and oxygen consumption during laparoscopic hysterectomy.
We evaluated the ventilatory effects and blood gas changes of prolonged CO2-pneumoperitoneum in nor-moventilated patients and examined the respiratory and gas exchange consequences of head-down positioning (25-30 degrees) and CO2 insufflation into the peritoneal cavity in 20 patients without major cardiorespiratory disorders in various phases of laparoscopic hysterectomy. The patients received general anesthesia with isoflurane, fentanyl, and vecuronium, and minute ventilation (MV) was adjusted to maintain the PETCO2 at 33-36 mm Hg throughout the entire procedure, either by increasing the tidal volume (TV) and keeping the respiratory rate (RR) at 12/min (10 patients) or by changing the RR and maintaining the TV at 8 mL/kg (10 patients). Arterial and mixed venous blood samples were collected simultaneously for blood gas analysis and for measurements of oxygen consumption, and respiratory mechanics and gases were recorded by an anesthetic gas analyzer and side stream spirometry device. ⋯ The compliance decreased by 20% with the head-down position and by an additional 30% with the increased intraabdominal pressure. PaCO2 and mixed venous PCO2 increased with CO2 insufflation, and the arterial to end-tidal PCO2 (a-etPCO2) gradient increased by 1.5 mm Hg during laparoscopy. A mild metabolic acidosis developed.(ABSTRACT TRUNCATED AT 250 WORDS)