Anesthesia and analgesia
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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)
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Anesthesia and analgesia · May 1995
The prone positioning during general anesthesia minimally affects respiratory mechanics while improving functional residual capacity and increasing oxygen tension.
We investigated the effects of the prone position on the mechanical properties (compliance and resistance) of the total respiratory system, the lung, and the chest wall, and the functional residual capacity (FRC) and gas exchange in 17 normal, anesthetized, and paralyzed patients undergoing elective surgery. We used the esophageal balloon technique together with rapid airway occlusions during constant inspiratory flow to partition the mechanics of the respiratory system into its pulmonary and chest wall components. FRC was measured by the helium dilution technique. ⋯ L-1.s, P < 0.05). Both FRC and PaO2 markedly (P < 0.01) increased from the supine to the prone position (1.9 +/- 0.6 vs 2.9 +/- 0.7 L, P < 0.01, and 160 +/- 37 vs 199 +/- 16 mm Hg, P < 0.01, respectively), whereas PaCO2 was unchanged. In conclusion, the prone position during general anesthesia does not negatively affect respiratory mechanics and improves lung volumes and oxygenation.