James D. Griffin

Dexmedetomidine infusion during laparoscopic bariatric surgery: the effect on recovery outcome variables.

BACKGROUND:Dexmedetomidine (Dex), an &agr;2 agonist, has well-known anesthetic and analgesic-sparing effects. We designed this prospective, randomized, double-blind, and placebo-controlled dose-ranging study to evaluate the effect of Dex on both early and late recovery after laparoscopic bariatric surgery. METHODS:Eighty consenting ASA II–III morbidly obese patients were randomly assigned to 1 of 4 treatment groups: (1) control group received a saline infusion during surgery, (2) Dex 0.2 group received an infusion of 0.2 &mgr;g · kg−1 · h−1 IV, (3) Dex 0.4 group received an infusion of 0.4 &mgr;g · kg−1 · h−1 IV, and (4) Dex 0.8 group received an infusion of 0.8 &mgr;g · kg−1 · h−1 IV. Mean arterial blood pressure values were maintained within ±25% of the preinduction baseline values by varying the inspired desflurane concentration. Perioperative hemodynamic variables, postoperative pain scores, and the need for “rescue” analgesics and antiemetics were recorded at specific intervals. Follow-up evaluations were performed on postoperative days (PODs) 1, 2, and 7 to assess severity of pain, analgesic requirements, patient satisfaction with pain management, quality of recovery, as well as resumption of dietary intake and recovery of bowel function. RESULTS:Dex infusion, 0.2, 0.4, and 0.8 &mgr;g · kg−1 · h−1, reduced the average end-tidal desflurane concentration by 19, 20, and 22%, respectively. However, it failed to facilitate a significantly faster emergence from anesthesia. Although the intraoperative hemodynamic values were similar in the four groups, arterial blood pressure values were significantly reduced in the Dex 0.2, 0.4, and 0.8 groups compared with the control group on admission to the postanesthesia care unit (PACU) (P < 0.05). The length of the PACU stay was significantly reduced in the Dex groups (81 ± 31 to 87 ± 24 vs 104 ± 33 min in the control group, P < 0.05). The amount of rescue fentanyl administered in the PACU was significantly less in the Dex 0.2, 0.4, and 0.8 groups versus control group (113 ± 85, 108 ± 67, and 120 ± 78 vs 187 ± 99 &mgr;g, respectively, P < 0.05). The percentage of patients requiring antiemetic therapy was also reduced in the Dex groups (30, 30, and 10% vs 70% in the control group). However, the patient-controlled analgesia morphine requirements on PODs 1 and 2 were not different among the four groups. Pain scores in the PACU, and on PODs 1, 2, and 7, in the three Dex groups were not different from the control group. Finally, quality of recovery scores and times to recovery of bowel function and hospital discharge did not differ among the four groups. CONCLUSIONS:Adjunctive use of an intraoperative Dex infusion (0.2–0.8 &mgr;g · kg−1 · h−1) decreased fentanyl use, antiemetic therapy, and the length of stay in the PACU. However, it failed to facilitate late recovery (e.g., bowel function) or improve the patients’ overall quality of recovery. When used during bariatric surgery, a Dex infusion rate of 0.2 &mgr;g · kg−1 · h−1 is recommended to minimize the risk of adverse cardiovascular side effects.

Comparison of Adenosine and Remifentanil Infusions as Adjuvants to Desflurane Anesthesia

BACKGROUND Because adenosine has been alleged to produce both anesthetic and analgesic sparing effects, a randomized, double-blinded study was designed to compare the perioperative effects of adenosine and remifentanil when administered as intravenous adjuvants during general anesthesia for major gynecologic procedures. METHODS Thirty-two women were assigned randomly to one of two drug treatment groups. After premedication with 0.04 mg/kg intravenous midazolam, anesthesia was induced with 2 micro/kg intravenous fentanyl, 1.5 mg/kg intravenous propofol, and 0.6 mg/kg intravenous rocuronium, and maintained with desflurane, 2%, and nitrous oxide, 65%, in oxygen. Before skin incision, an infusion of either remifentanil (0.02 microg x kg(-1) x min(-1)) or adenosine (25 microg x kg(-1) x min(-1)) was started and subsequently titrated to maintain systolic blood pressure, heart rate, or both within 10-15% of the preincision values. RESULTS Adenosine and remifentanil infusions were effective anesthetic adjuvants during lower abdominal surgery. Use of adenosine (mean +/- SEM, 166+/-17 microg x kg(-1) x min(-1)) was associated with a significantly greater decrease in systolic blood pressure and higher heart rate values compared with remifentanil (mean +/- SEM, 0.2+/-0.03 microg kg(-1) x min(-1)). Total postoperative opioid analgesic use was 45% and 27% lower in the adenosine group at 0-2 h and 2-24 h after surgery, respectively. CONCLUSIONS Adjunctive use of a variable-rate infusion of adenosine during desflurane-nitrous oxide anesthesia was associated with acceptable hemodynamic stability during the intraoperative period. Compared with remifentanil, intraoperative use of adenosine was associated with a decreased requirement for opioid analgesics during the first 24 h after operation.

Optimal Dose of Nicardipine for Maintenance of Hemodynamic Stability After Tracheal Intubation and Skin Incision

To determine the optimal dose of nicardipine (N) for maintenance of hemodynamic stability during the postinduction period, we designed a randomized, double-blind, placebo-controlled, dose-ranging study using four different doses of N administered after a standardized anesthetic induction sequence. A total of 106 patients were assigned to one of the following treatment groups: saline (control), N0.5 mg (N0.5), N1 mg (N1), N2 mg (N2), and N4 mg (N4). The study medication was administered intravenously (IV) in 2.5 mL of saline over 30 s 2 min before laryngoscopy. Mean arterial pressure (MAP) and heart rate (HR) were recorded at 1-min intervals for 15 min after tracheal intubation and for 5 min after skin incision. After intubation, the peak MAP values differed from the preinduction baseline MAP values by 21% +/- 20%, 9% +/- 12%, 1% +/- 13%, -10% +/- 12%, and -15% +/- 13% (mean +/- SD) in the control, N0.5, N1, N2, and N4 groups, respectively. However, the percent change in the pre- to postintubation MAP values (37% to 47%) was similar in all five groups. The highest postintubation HR values were recorded in the N4 group (P < 0.05 versus the other groups). However, the increases in MAP values after skin incision were the least in the N4 group. In conclusion, N1 IV, administered 2 min before laryngoscopy provides optimal control of arterial blood pressure during the postinduction period. Implications: Acute increases in blood pressure during anesthesia are undesirable in patients with preexisting cardiovascular diseases. This double-blind study found that the calcium-channel blocker, nicardipine, 1 mg intravenously 2 min before tracheal intubation maintained hemodynamic stability during the intraoperative period. (Anesth Analg 1997;85:1247-51)

The effect of fresh gas flow and anesthetic technique on the ability to control acute hemodynamic responses during surgery

We evaluated the effect of the fresh gas flow (FGF) rate and the anesthetic technique on the ability to control the acute hyperdynamic response to a specific surgical stimulus during surgery in 90 consenting ASA physical status I-III patients undergoing lower abdominal procedures. After the administration of midazolam 2 mg IV, anesthesia was induced in all patients with propofol 1.5 mg/kg IV and fentanyl 1 [micro sign]g/kg IV and was initially maintained with desflurane or isoflurane, 0.7 minimum alveolar anesthetic concentration, at total FGF rates of either 1 or 3 L/min. In response to the surgical stimulation of skin incision and retropubic dissection, an increase in mean arterial pressure (MAP) >20% above the preincision baseline MAP value provoked a stepwise increase in the inspired concentration of the volatile anesthetic or the IV administration of a variable-rate infusion of esmolol. At both FGF rates, the acute hemodynamic response to surgical stimulation was more efficiently treated by increasing the inspired concentration of desflurane than isoflurane. At 1 L/min, the average time to control the increase in MAP was significantly shorter with desflurane (17 +/- 12 min) compared with isoflurane (29 +/- 16 min), with 60% of the patients in the isoflurane group requiring rescue therapy. When an esmolol infusion was used to control the increase in MAP, supplementation with fentanyl was required in 40% and 53% of patients anesthetized with desflurane and isoflurane, respectively. In conclusion, desflurane provided more rapid and reliable control of acute hemodynamic responses to surgical stimulation than isoflurane or esmolol when the volatile anesthetics were administered at low FGF rates. Implications: At low fresh gas flow rates (1 L/min), desflurane more successfully and rapidly controlled the acute hemodynamic responses to painful surgical stimuli than isoflurane. (Anesth Analg 1998;87:666-70)

Use of the cuffed oropharyngeal airway as an alternative to the laryngeal mask airway with positive-pressure ventilation

BACKGROUND The cuffed oropharyngeal airway is a modified Guedel-type oral airway with a cuff at its distal end. The objectives of this study were to compare the ability of the cuffed oropharyngeal airway and the laryngeal mask airway to provide positive-pressure ventilation during general anesthesia, and to assess their relative ease of use and ability to reduce total fresh gas flow rates. METHODS In this prospective, randomized study, a cuffed oropharyngeal airway (n = 25) or a laryngeal mask airway (n = 25) device was inserted after induction of anesthesia intravenously using 2 mg/kg propofol. While anesthesia was maintained with sevoflurane and nitrous oxide, the leak pressure, leak fraction (the fractional difference between the inspired and expired tidal volume), minimum fresh gas flow rate, and need for airway manipulations were determined. The anesthesia provider who inserted the device completed an evaluation form at the end of the 15-min study period. RESULTS Positive-pressure ventilation was established successfully on the first attempt in 92% of the patients when the cuffed oropharyngeal airway was used and in 88% of the patients when the laryngeal mask airway device was used. However, manipulations of the airway device were necessary more frequently (8 vs. 1 patient; P < 0.05) and the leak pressure was less (22 +/- 6 cm water vs. 26 +/- 5 cm water; P < 0.05) with the cuffed oropharyngeal airway than with the laryngeal mask airway. In addition, the leak fraction (0.19 +/- 0.18 vs. 0.31 +/- 0.22; P < 0.05) and the minimum fresh gas flow rate (1.3 +/- 1.5 vs. 2.4 +/- 2.5; P = 0.12) were less in the laryngeal mask airway group. CONCLUSIONS Positive-pressure ventilation is possible with the laryngeal mask airway and cuffed oropharyngeal airway devices. Although the cuffed oropharyngeal airway can be inserted easily by inexperienced users with a high first-attempt success rate (> 90%), manipulations of the device may be required to maintain a patent airway. The laryngeal mask airway device allows positive-pressure ventilation at slightly greater peak inspiratory pressures.

A cost comparison of methohexital and propofol for ambulatory anesthesia

UNLABELLED Methohexital is eliminated more rapidly than thiopental, and early recovery compares favorably with propofol. We designed this study to evaluate the recovery profile when methohexital was used as an alternative to propofol for the induction of anesthesia before either sevoflurane or desflurane in combination with nitrous oxide. One hundred twenty patients were assigned randomly to one of four anesthetic groups: (I) methohexital-desflurane, (II) methohexital-sevoflurane, (III) propofol-desflurane, or (IV) propofol-sevoflurane. Recovery times after the anesthetic drugs, as well as the perioperative side effect profiles, were similar in all four groups. A cost-minimization analysis revealed that methohexital was less costly for the induction of anesthesia. At the fresh gas flow rates used during this study, the costs of the volatile anesthetics for maintenance of anesthesia did not differ among the four groups. However, at low flow rates (< or = 1 L/min), the methohexital-desflurane group would have been the least expensive anesthetic technique. In conclusion, methohexital is a cost-effective alternative to propofol for the induction of anesthesia in the ambulatory setting. At low fresh gas flow rates, the methohexital-desflurane combination was the most cost-effective for the induction and maintenance of general anesthesia. IMPLICATIONS Using methohexital as an alternative to propofol for the induction of anesthesia for ambulatory surgery seems to reduce drug costs. When fresh gas flow rates < or = 1 L/min are used, the combination of methohexital for the induction and desflurane for maintenance may be the most cost-effective general anesthetic technique for ambulatory surgery.