Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1999
Comparative StudyFactors contributing to a prolonged stay after ambulatory surgery.
We identified predictors for prolonged postoperative stay after ambulatory surgery using multiple logistic regression models. We collected perioperative data for 16,411 ambulatory surgical patients. A log-transformed time to discharge variable was modeled by multiple linear regression, including patient-, anesthesia-, and surgery-specific variables. The impact of hypothetical elimination of perioperative adverse events on mean length of stay was also estimated. Separate analyses were performed among patients who received general anesthesia (GA) and monitored anesthesia care (MAC). Patients receiving GA stayed 50 min longer than patients receiving MAC. Patients receiving GA and undergoing strabismus, transurethral, or otorhinolaryngological/dental procedures had the longest postoperative stay. Among patients receiving GA, smokers had a 4% shorter stay compared with nonsmokers; among patients receiving MAC, those with congestive heart failure (CHF) had a 11% longer stay compared with patients without CHF. Postoperative nausea and vomiting, dizziness, excessive pain, and cardiovascular events predicted 22%-79% increases in postoperative stay. The hypothetical elimination of all adverse events resulted in a 9.6% decrease in mean length of stay among patients receiving GA, but in only a 3.8% decrease among patients receiving MAC. The length of postoperative stay among ambulatory surgical patients is mainly determined by the type of surgery and by adverse events, such as excessive pain, postoperative nausea and vomiting, dizziness, drowsiness, and cardiovascular events. Patients with CHF and those who underwent long procedures had a higher risk of a prolonged stay. Appropriate prevention and management of postoperative symptoms could significantly decrease the length of stay among patients receiving GA. ⋯ The length of postoperative stay among ambulatory surgical patients is mainly determined by the type of surgery and by adverse events, such as excessive pain, postoperative nausea and vomiting, dizziness, drowsiness, and untoward cardiovascular events. Patients with congestive heart failure and those who underwent long procedures had a higher risk of a prolonged stay. Appropriate prevention and management of postoperative symptoms could significantly decrease the length of stay among patients receiving general anesthesia.
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Anesthesia and analgesia · Dec 1999
Attenuated additional hypocapnic constriction, but not hypercapnic dilation, of spinal pial arterioles during spinal ropivacaine.
Ropivacaine constricts spinal vessels. Because the CO2 response of spinal vessels is similar to that of cerebral vessels, we tested to see if hypocapnia would cause further spinal vasoconstriction during ropivacaine administration. In 12 pentobarbital-anesthetized dogs, spinal pial arteriolar diameter was measured using a closed spinal window preparation. Either ropivacaine solution (0.1%; n = 6) or artificial cerebrospinal fluid (n = 6) was infused continuously into the spinal window. After a period of hypocapnia (Paco2, 20-25 mm Hg) had been induced, inspired CO2 levels were adjusted to produce normocapnia (35-40 mm Hg) followed by hypercapnia (55-60 mm Hg). When the desired Paco2 was reached, measurements were made of the arteriolar diameter and physiological variables. During normocapnia, ropivacaine infusion produced a significant constriction of pial arterioles, whereas artificial cerebrospinal fluid caused no change. Hypocapnia induced a much smaller (almost nonexistent) additional vasoconstriction in the ropivacaine group than in the control group (P < 0.01). The final hypercapnic vasodilation was somewhat greater during ropivacaine (P < 0.05 versus control group). Topical ropivacaine induced no change in hemodynamic variables. We conclude that hypocapnia of the magnitude tested did not cause further constriction in spinal vessels during spinal ropivacaine. ⋯ During topical application of the local anesthetic ropivacaine in dogs, hypocapnia (Paco2, 20-25 mm Hg) induced almost no additional constriction of spinal arterioles, and the hypercapnic vasodilation was maintained. These data suggest that an additional constriction in spinal vessels is unlikely when hypocapnia occurs during spinal ropivacaine.
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Anesthesia and analgesia · Dec 1999
Effect of small-dose dopamine on mesenteric blood flow and renal function in a pig model of cardiopulmonary resuscitation with vasopressin.
Vasopressin (antidiuretic hormone) seems a promising alternative to epinephrine for cardiopulmonary resuscitation (CPR) in cardiac arrest victims, mediating a pronounced blood flow shift toward vital organs. We evaluated the effects of small-dose dopamine on splanchnic blood flow and renal function after successful resuscitation with this potent vasoconstrictor in an established porcine CPR model. After 4 min of cardiac arrest and 3 min of CPR, animals received 0.4 U/kg vasopressin and were continuously infused with either dopamine 4 microg x kg(-1) x min(-1) (n = 6), or saline placebo (n = 6). Defibrillation was performed 5 min after drug administration; all animals were observed for 6 h after return of spontaneous circulation. During the postresuscitation phase, average mean +/- SD superior mesenteric artery blood flow was significantly (P = 0.002) higher in the dopamine group compared with the placebo group (1185+/-130 vs 740+/-235 mL/min), whereas renal blood flow was comparable between groups (255+/-40 vs 250+/-85 mL/min). The median calculated glomerular filtration rate had higher values in the dopamine group (70-120 mL/min) than in the placebo group (40-70 mL/min; P = 0.1 at 0 min and P = 0.08 at 360 min). We conclude that small-dose dopamine administration may be useful in improving superior mesenteric artery blood flow and renal function after successful resuscitation with vasopressin. ⋯ Long-term survival after cardiac arrest may be determined by the ability to ensure adequate organ perfusion during cardiopulmonary resuscitation and in the postresuscitation phase. In this regard, small-dose dopamine improved postresuscitation blood flow to the mesenteric bed when vasopressin was used as an alternative vasopressor in an animal model of cardiac arrest.
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Volatile anesthetics depress diaphragmatic muscle function; however, no data are available regarding the effect of propofol on diaphragmatic contractility. We therefore studied this effect in dogs. Pentobarbital-anesthetized animals were divided into three groups of 10 each. Group I received only maintenance fluid; Group II was infused with a subhypnotic dose of propofol (0.1-mg/kg initial dose plus 1.5-mg x kg(-1) x h(-1) maintenance dose); Group III was infused with an anesthetic dose of propofol (0.1-mg/kg initial dose plus 6.0-mg x kg(-1) x h(-1) maintenance dose). We assessed diaphragmatic contractility by transdiaphragmatic pressure (Pdi). With an infusion of propofol in Groups II and III, Pdi at low-frequency (20-Hz) stimulation decreased from the baseline values (P < 0.05), whereas Pdi at high-frequency (100-Hz) stimulation did not change. Compared with Group I, Pdi at 20-Hz stimulation decreased during propofol administration in Groups II and III (P < 0.05). The decrease in Pdi was more in Group III than in Group II (P < 0.05). We conclude that propofol is associated with a dose-related inhibitory effect on diaphragmatic contractility in dogs. ⋯ Propofol is an effective IV anesthetic for the induction and maintenance of anesthesia. Subhypnotic and anesthetic doses of propofol decrease diaphragmatic contractility in dogs.