Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Comparative Study Clinical TrialNormal saline versus lactated Ringer's solution for intraoperative fluid management in patients undergoing abdominal aortic aneurysm repair: an outcome study.
Metabolic acidosis and changes in serum osmolarity are consequences of 0.9% normal saline (NS) solution administration. We sought to determine if these physiologic changes influence patient outcome. Patients undergoing aortic reconstructive surgery were enrolled and were randomly assigned to receive lactated Ringer's (LR) solution (n = 33) or NS (n = 33) in a double-blinded fashion. Anesthetic and fluid management were standardized. Multiple measures of outcome were monitored. The NS patients developed a hyperchloremic acidosis and received more bicarbonate therapy (30 +/- 62 mL in the NS group versus 4 +/- 16 mL in the LR group; mean +/- SD), which was given if the base deficit was greater than -5 mEq/L. The NS patients also received a larger volume of platelet transfusion (478 +/- 302 mL in the NS group versus 223 +/- 24 mL in the LR group; mean +/- SD). When all blood products were summed, the NS group received significantly more blood products (P = 0.02). There were no differences in duration of mechanical ventilation, intensive care unit stay, hospital stay, and incidence of complications. When NS was used as the primary intraoperative solution, significantly more acidosis was seen on completion of surgery. This acidosis resulted in no apparent change in outcome but required larger amounts of bicarbonate to achieve predetermined measurements of base deficit and was associated with the use of larger amounts of blood products. These changes should be considered when choosing fluids for surgical procedures involving extensive blood loss and requiring extensive fluid administration. ⋯ Predominant use of 0.9% saline solution in major surgery has little impact on outcome as assessed by duration of mechanical ventilation, intensive care unit stay, hospital stay, and postoperative complications, but it does appear to be associated with increased perioperative blood loss.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Clinical TrialThe effects of balanced versus saline-based hetastarch and crystalloid solutions on acid-base and electrolyte status and gastric mucosal perfusion in elderly surgical patients.
The IV administration of sodium chloride solutions may produce a metabolic acidosis and gastrointestinal dysfunction. We designed this trial to determine whether, in elderly surgical patients, crystalloid and colloid solutions with a more physiologically balanced electrolyte formulation, such as Hartmann's solution and Hextend, can provide a superior metabolic environment and improved indices of organ perfusion when compared with saline-based fluids. Forty-seven elderly patients undergoing major surgery were randomly allocated to one of two study groups. Patients in the Balanced Fluid group received an intraoperative fluid regimen that consisted of Hartmann's solution and 6% hetastarch in balanced electrolyte and glucose injection (Hextend). Patients in the Saline group were given 0.9% sodium chloride solution and 6% hetastarch in 0.9% sodium chloride solution (Hespan). Biochemical indices and acid-base balance were determined. Gastric tonometry was used as a reflection of splanchnic perfusion. Postoperative chloride levels demonstrated a larger increase in the Saline group than the Balanced Fluid group (9.8 vs 3.3 mmol/L, P = 0.0001). Postoperative standard base excess showed a larger decline in the Saline group than the Balanced Fluid group (-5.5 vs -0.9 mmol/L, P = 0.0001). Two-thirds of patients in the Saline group, but none in the Balanced Fluid group, developed postoperative hyperchloremic metabolic acidosis (P = 0.0001). Gastric tonometry indicated a larger increase in the CO2 gap during surgery in the Saline group compared with the Balanced Fluid group (1.7 vs 0.9 kPa, P = 0.0394). In this study, the use of balanced crystalloid and colloid solutions in elderly surgical patients prevented the development of hyperchloremic metabolic acidosis and resulted in improved gastric mucosal perfusion when compared with saline-based solutions. ⋯ This prospective, randomized, blinded trial showed that, in elderly surgical patients, the use of balanced IV solutions can prevent the development of hyperchloremic metabolic acidosis and provide better gastric mucosal perfusion compared with saline-based fluids.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Comparative Study Clinical TrialAmbulatory surgery: room air versus nasal cannula oxygen during transport after general anesthesia.
We compared outpatients transported to the postanesthesia care unit (PACU) while breathing room air to 2-4 L/min nasal cannula oxygen (O2) to test the hypothesis that routine supplemental O2 during transport is not required after general anesthesia in an ambulatory surgery center. We also examined whether the arbitrary arrival PACU O2 saturations of > 92% may be used to predict an infrequent incidence of subsequent significant desaturations (< 90%) in the PACU. One-hundred-ninety patients were randomized to receive either room air or 2-4 L/min nasal cannula for transport to PACU after receiving general anesthesia. O2 saturations were recorded before surgery, just before leaving the operating room, and upon arrival in the PACU. The lowest O2 saturation occurring in the PACU was also recorded. The mean arrival PACU O2 saturation was 95.0 in the Room Air group, compared with 97.2 for the Nasal Cannula (NC) group, a statistically significant difference (P < 0.001). In the Room Air group, 20% had arrival O2 saturations < or = 92%, and half of these (10%) had O2 saturations < 90%. In the NC group, 6% had O2 saturations < or = 92%, of which one third (2%) were < 90% on arrival in the PACU. All of these initial desaturations were easily corrected with face-tent O2 administration, deep breathing, or both. Subgroup analysis revealed that patients whose ages were 60 yr or older or those weighing 100 kg or more had lower arrival room air saturations than their younger or slimmer counterparts. In the Room Air group, only three (3.9%) of the patients that arrived in PACU with O2 saturations > 92% had subsequent desaturations < 90%, compared with seven (7.9%) in the NC group. We conclude that most adult patients undergoing ambulatory surgery can be transported safely to the PACU breathing room air after general anesthesia. However, patients whose age was > or = 60 yr or weight was > or = 100 kg, or for whom transient O2 desaturation on transport may be harmful, should be transported while breathing nasal O2 via nasal cannula. ⋯ Most adult patients undergoing ambulatory surgery can be transported safely to the PACU breathing room air after general anesthesia. However, patients whose age was > or = 60 yr or weight > or = 100 kg, or for whom transient O2 desaturation on transport may be harmful, should be transported while breathing oxygen via nasal cannula.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Comparative Study Clinical TrialInduction of anesthesia with ketamine reduces the magnitude of redistribution hypothermia.
Hypothermia after induction of general anesthesia results largely from core-to-peripheral redistribution of body heat. Both central inhibition of tonic thermoregulatory vasoconstriction in arteriovenous shunts and anesthetic-induced arteriolar and venous dilation contribute to this redistribution. Ketamine, unique among anesthetics, increases peripheral arteriolar resistance; in contrast, propofol causes profound venodilation that other anesthetics do not. We therefore tested the hypothesis that induction of anesthesia with ketamine causes less core hypothermia than induction with propofol. Twenty patients undergoing elective surgery were randomly assigned to anesthetic induction with either 1.5 mg/kg ketamine (n = 10) or 2.5 mg/kg propofol (n = 10). Anesthesia in both groups was subsequently maintained with sevoflurane and 60% nitrous oxide in oxygen. Forearm minus finger, skin-temperature gradients <0 degrees C were considered indicative of significant arteriovenous shunt vasodilation. Ketamine did not cause vasodilation just after induction, whereas propofol rapidly induced vasodilation. Core temperatures in the patients given ketamine remained significantly greater than those in the patients induced with propofol. These data suggest that maintaining vasoconstriction during induction of anesthesia reduces the magnitude of redistribution hypothermia. ⋯ Core hypothermia during the first hour of anesthesia was less after induction of anesthesia with ketamine than propofol. Maintaining arteriovenous shunt vasoconstriction during induction of anesthesia reduces the magnitude of redistribution hypothermia.
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Anesthesia and analgesia · Oct 2001
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of fentanyl, sufentanil, and remifentanil for fast-track cardiac anesthesia.
Cardiac surgery is estimated to cost $27 billion annually in the United States. In an attempt to decrease the costs of cardiac surgery, fast-track programs have become popular. The purpose of this study was to compare the effects of three different opioid techniques for cardiac surgery on postoperative pain, time to extubation, time to intensive care unit discharge, time to hospital discharge, and cost. Ninety adult patients undergoing cardiac surgery were randomized to a fentanyl-based, sufentanil-based, or remifentanil-based anesthetic. Postoperative pain was measured at 30 min after extubation and at 6:30 AM on the first postoperative day. Pain scores at both times were similar in all three groups (P > 0.05). Median ventilator times of 167, 285, and 234 min (P > 0.05), intensive care unit stays of 18.8, 19.8, and 21.5 h (P > 0.05), and hospital stays of 5, 5, and 5 days (P > 0.05) for the Fentanyl, Sufentanil, and Remifentanil groups did not differ. Three patients needed to be tracheally reintubated: two in the Sufentanil group and one in the Fentanyl group. Median anesthetic costs were largest in the Remifentanil group ($140.54 [$113.54-$179.29]) and smallest in the Fentanyl group ($43.33 [$39.36-$56.48]) (P < or = 0.01), but hospital costs were similar in the three groups: $7841 (Fentanyl), $5943 (Sufentanil), and $6286 (Remifentanil) (P > 0.05). We conclude that the more expensive but shorter-acting opioids, sufentanil and remifentanil, produced equally rapid extubation, similar stays, and similar costs to fentanyl, indicating that any of these opioids can be recommended for fast-track cardiac surgery. ⋯ To conserve resources for cardiac surgery, fentanyl-, sufentanil-, and remifentanil-based anesthetics were compared for duration of mechanical ventilation, intensive care unit length of stay, hospital length of stay, and cost. The shorter-acting anesthetics, sufentanil and remifentanil, produced equally rapid extubation, similar stays, and similar costs to fentanyl; thus, any of these opioids can be recommended for fast-track cardiac surgery.