An obese 50-yrs-old woman undergoes a laparoscopic

Discussion in 'MRCS Forum' started by Lona., Dec 6, 2007.

  1. Lona.

    Lona. Guest

    An obese 50-yrs-old woman undergoes a laparoscopic cholecystectomy. In the recovery room, she is found to be hypotensive and tachycardic. Her arterial blood gases reveal a pH of 7.29, Pao2 of 60 kPa, and Paco2 of 54 kPa. The most likely cause of this woman’s problem is-
    a- Acute pulmonary embolism
    b- CO2 absorption from induced pneumoperitoneum
    c- Alveolar hypoventilation
    d- Pulmonary edema
    e- Atelectasis from high diaphragm
  2. Lona.

    Lona. Guest

    Answer: c. (Schwartz, 7/e, pp 494-496) because of the ease with which carbon dioxide diffuses across the alveolar membranes, Paco2 is a highly reliable indicator of alveolar ventilation. In this postoperative patient with respiratory acidosis and hypoxemia, the hypercarbia is diagnostic of alveolar hypoventilation. Acute hypoxemia can occur with pulmonary embolism, pulmonary edema and significant Atelectasis, but in all those situations the Paco2 should be normal or reduced as the patient hyperventilates to improve oxygenation. The absorption of gas from the peritoneal cavity may transiently affect the Paco2, but should have no effect on oxygenation.

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