PHYSIOLOGIC EFFECTS OF ANESTHESIA & SURGERY


Both general and spinal or epidural anesthetic agents usually cause peripheral vasodilation, and most of the commonly used general anesthetic regimens also decrease myocardial contractility. These effects often result in transient mild hypotension or, less frequently, prolonged or more severe hypotension. The decrease in tidal volume caused by general and spinal-epidural anesthesia can close small airways and lead to atelectasis. Epinephrine, norepinephrine, and cortisol levels increase during surgery and remain elevated for 1–3 days. Serum antidiuretic hormone levels may be elevated for up to 1 week postoperatively. There is some evidence that general anesthesia may be associated with a relative hypercoagulable state during the perioperative period. This does not occur with spinal or epidural anesthesia. The degree to which this hypercoagulability contributes to perioperative morbidity is not known.
There is no evidence that spinal or epidural anesthesia is preferable to general anesthesia in terms of cardiac outcomes or overall surgical outcomes. Similarly, there is no conclusive evidence that the routine use of invasive hemodynamic monitoring with pulmonary artery catheters improves surgical outcomes. In general, the choice of anesthetic technique or agent and the decision to use invasive hemodynamic monitoring should be left to the anesthesiologist.


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