Volume 4, Issue 4 S A M B A T A L K S - PAGE 3 September, 2004

FROM THE LITERATURE: - TOP


ANESTHESIA AND ANALGESIA - TOP

The Analgesic Effects of Gabapentin in Monitored Anesthesia Care for Ear-Nose-Throat Surgery
Alparslan Turan, M, Dilek Memi, MD, Beyhan Karamanl o lu, MD, Recep Ya z, MD, Zafer Pamukçu, MD, and Ebru Yavuz
Anesth Analg 2004;99:375-378

We investigated the efficacy and safety of gabapentin in rhinoplasty or endoscopic sinus surgery patients. Patients received either oral placebo or gabapentin 1200 mg 1 h before surgery. After standard premedication, 25 patients in each group received propofol, fentanyl, and local anesthesia at the operative site. Sedation was maintained by a continuous infusion of propofol adjusted according to the Ramsay scale. Sedation and pain scores were obtained at 5, 15, 30, 45, and 60 min during surgery and 30 min and 2, 4, 6, 8, 12, 16, 20, and 24 h after the procedure. Diclofenac 75 mg IM was administered as a rescue analgesic. Postoperative pain scores and intraoperative pain scores at 45 and 60 min were significantly lower in the gabapentin group. Fentanyl (122 ± 40 µg versus 148 ± 42 µg; P < 0.05) and diclofenac (33 ± 53 mg versus 111 ± 92 mg; P < 0.001) consumption was smaller and the time to first analgesic request (18 ± 9 h versus 9 ± 7 h; P < 0.001) was longer in the gabapentin group. A more frequent incidence of dizziness was found in the gabapentin (versus placebo) group (24% versus 4%, respectively). We conclude that gabapentin provided a significant analgesic benefit for intraoperative and postoperative pain relief in patients undergoing ambulatory rhinoplasty or endoscopic sinus surgery; however, dizziness may be a handicap for ambulatory use.
IMPLICATIONS: Gabapentin has been demonstrated to be effective in different pain models. This study demonstrated that gabapentin decreases intraoperative and postoperative pain scores and analgesic requirements in rhinoplasty or endoscopic sinus surgery patients; however, dizziness may be a handicap for use in ambulatory patients.

Capnography Accurately Detects Apnea During Monitored Anesthesia Care
Roy G. Soto, MD, Eugene S. Fu, MD, Hector Vila, Jr., MD, and Rafael V. Miguel, MD
Anesth Analg 2004;99:379-382

Apnea and airway obstruction are common during monitored anesthesia care (MAC). Because their early detection is essential, we sought to measure the efficacy of capnography as an indicator of apnea during MAC at a variety of oxygen flow rates compared with thoracic impedance. Anesthesia care providers using standard American Society of Anesthesiologists monitors were blinded to capnography and thoracic impedance monitoring. Ten (26%) of the 39 patients studied developed 20 s of apnea; none was detected by the anesthesia provider, but all were detected by capnography and impedance monitoring. There was no difference in detection rates between the two methods. Higher oxygen flow rates decreased the amplitude of the capnograph but did not interfere with apnea detection. This pilot study revealed that apnea of at least 20 s in duration may occur in every fourth patient undergoing MAC. Although these episodes were undetected by the anesthesia provider, they were reliably detected by both capnography and respiratory plethysmography. Monitoring of nasal end-tidal CO₂ is an important way to improve safety in patients undergoing MAC.
IMPLICATIONS: Capnography is not a mandatory monitor for monitored anesthesia care procedures, nor is it required for sedation performed outside of the operating room, although there are practice guidelines that suggest that monitoring of ventilatory function be used to reduce the risk of adverse outcomes. Use of capnography can enhance detection of apnea during sedation procedures and potentially improve patient safety.

Unsuspected Temporomandibular Joint Pathology Leading to a Difficult Endotracheal Intubation
Robert H. Small, MD, Steven I. Ganzberg, DMD, and Andreas W. Schuster, MD
Anesth Analg 2004;99:383-385

A 40-yr-old woman with an unremarkable medical history and no prior surgeries presented for ambulatory surgery. Physical examination revealed normal jaw opening. On induction of general anesthesia, her jaw was found to be locked in a nearly closed position. We discuss anesthetic considerations and the pathology of temporomandibular joint anterior disk dislocation without reduction. A simple maneuver to reduce the dislocation is described.
IMPLICATIONS: The result of failing to secure the airway of a patient undergoing general anesthesia can be catastrophic. It is ominous when there is a condition that makes airway management difficult and that is not easily diagnosed in advance. This report discusses one such condition and describes a technique to overcome the difficulty.

Seizures After a Bier Block with Clonidine and Lidocaine
Shihab U. Ahmed, MB BS, MPH, Ricardo Vallejo, MD PhD, and E. Daniela Hord, MD
Anesth Analg 2004;99:593-594

A 47-yr-old man with history of complex regional pain syndrome type 1 underwent an IV Bier block with a mixture of lidocaine and clonidine. The tourniquet was deflated after 60 min, and approximately 10 min later he presented with complex partial seizures. The possible mechanisms for this are discussed, and the effects of clonidine, lidocaine, and the mixture of both are reviewed, as are four additional published cases reporting seizures after the administration of clonidine.
IMPLICATIONS: Clonidine is being used increasingly as an adjuvant medication for neuropathic pain and to improve the duration of regional anesthesia. Four cases of seizures associated with the use of clonidine have been reported. We present a case of seizure after a Bier block with lidocaine and clonidine in a patient with complex regional pain syndrome type I.

ANESTHESIOLOGY - TOP

Effects of Bispectral Index Monitoring on Ambulatory Anesthesia: A Meta-analysis of Randomized Controlled Trials and a Cost Analysis.
Liu, Spencer S. M.D.
Anesthesiology 2004; 101: 311-5

Background: Ambulatory surgery is growing in popularity worldwide. For example, 50-70% of surgical procedures in North America are performed on an ambulatory basis. Use of Bispectral Index (BIS) monitoring for titration of general anesthesia may allow use of less anesthetics, reduction in side effects, and faster patient recovery.
Methods: MEDLINE and other databases were searched for randomized controlled trials examining the use of BIS monitoring versus standard practice in ambulatory surgery patients. Outcomes were extracted from these articles, and a meta-analysis was performed.
Results: One thousand three hundred eighty subjects from 11 trials were included in the meta-analysis. The use of BIS monitoring significantly reduced anesthetic consumption by 19%, reduced the incidence of nausea/vomiting (32% vs. 38%; odds ratio, 0.77), and reduced time in the recovery room by 4 min. However, these benefits did not result in significant reduction in time until patient discharge from the ambulatory surgery unit. Cost analysis using pooled costs to reflect North America, Europe, and Asia indicated that use of BIS monitoring increased the cost per patient by 5.55 US dollars because of the cost of BIS electrodes.
Conclusions: The use of BIS monitoring modestly reduced anesthetic consumption, risk of nausea and vomiting, and recovery room time. These benefits did not reduce time spent in the ambulatory surgery unit, and cost of the BIS electrode exceeded any cost savings.

A Randomized Controlled Trial Comparing the ProSeal TM Laryngeal Mask Airway with the Laryngeal Tube Suction in Mechanically Ventilated Patients.
Gaitini, Luis A. M.D ; Vaida, Sonia J. M.D. ; Somri, Mostafa M.D.; Yanovski, Boris M.D.; Ben-David, Bruce M.D.; Hagberg, Carin A. M.D.
Anesthesiology 2004; 101:316-20.

Background: The ProSeal^TM Laryngeal Mask Airway (PLMA) (Laryngeal Mask Company, Henley-on-Thames, United Kingdom) is a new laryngeal mask with a modified cuff designed to improve its seal and a drain tube for gastric tube placement. Similarly, the Laryngeal Tube Suction (LTS) (VBM Medizintechnik Gmbh, Sulz a.N, Germany) is a new laryngeal tube that also has an additional channel for gastric tube placement. This study compared the placement and functions of these two devices.
Methods: One hundred fifty patients undergoing general anesthesia for elective surgery were randomly allocated to the PLMA (n = 75) or LTS (n = 75). Oxygenation and ventilation, ease of insertion, fiberoptic view, oropharyngeal leak pressure, ventilatory data, ease of gastric tube insertion, and postoperative airway morbidity were determined.
Results: After successful insertion of the devices in 96% of patients with the PLMA and in 94.4% with the LTS it was possible to maintain oxygenation, ventilation, and respiratory mechanics during the entire duration of surgery. Successful first and second attempt insertion rates were 57 patients (76%) and 15 patients (20%), respectively, for the PLMA and 60 patients (80%) and 11 patients (14.6%), respectively, for the LTS. Airway placement was unsuccessful with the PLMA in three patients and with the LTS in four patients. Time to achieve an effective airway was 36 +/- 24 s with the PLMA versus 34 +/- 25 s with the LTS. Gastric tube insertion was possible in 97.3% of patients with the PLMA and in 96% with the LTS.
Conclusions: With respect to both physiologic and clinical function, the PLMA and LTS are similar and either device can be used to establish a safe and effective airway in mechanically ventilated anesthetized adult patients.

A Comparison of Sex- and Weight-based ProSeal^TM Laryngeal Mask Size Selection Criteria: A Randomized Study of Healthy Anesthetized, Paralyzed Adult Patients
Kihara, Shinichi M.D.; Brimacombe, Joseph R. F.R.C.A., M.D.; Yaguchi, Yuichi M.D..; Taguchi, Noriko M.D.; Watanabe, Seiji M.D.
Anesthesiology 2004; 101:340-3.

Background: The authors compared the manufacturer's weight-based formula (size 3 for weight < 50 kg, size 4 for weight 50-70 kg, and size 5 for weight > 70 kg) with a sex-based formula (size 4 for women and size 5 for men) for selecting the appropriate size of ProSeal^TM laryngeal mask airway.
Methods : Two hundred thirty-seven healthy, anesthetized, paralyzed adult patients (American Society of Anesthesiologists physical status I or II; age, 18-80 yr) were randomly allocated for weight- or sex-based size selection. An experienced user inserted the ProSeal^TM laryngeal mask airway with the digital technique. The following were compared: ease of insertion, oropharyngeal leak pressure, ease of ventilation, gas exchange, location of gas leak, anatomic position, mucosal injury, and postoperative pharyngolaryngeal problems. Intraoperative and postoperative data collection were unblinded and blinded, respectively.
Results: Ease of insertion, anatomic position, gas exchange, mucosal injury, and postoperative pharyngolaryngeal problems were similar between groups. For the sex-based group, larger ProSeal^TM laryngeal mask airways were selected more frequently (P < 0.0001), oropharyngeal leak pressure (P = 0.02) was higher, leak volume (P = 0.004) and leak fraction (P = 0.007) were lower, and oropharyngeal leaks (P = 0.03) were detected less frequently.
Conclusion: Size selection for the ProSeal^TM laryngeal mask airway is equally effective using the manufacturer's weight-based formula or the sex-based formula in healthy, anesthetized, paralyzed adult patients, but leakage of small volumes of air from the mouth occurs less frequently with the sex-based formula.

Early but No Long-term Benefit of Regional Compared with General Anesthesia for Ambulatory Hand Surgery.
McCartney, Colin J. L. M.B.Ch.B., F.C.A.R.C.S.I., F.R.C.P.C.; Brull, Richard M.D., F.R.C.P.C; Chan, Vincent W. S. M.D., F.R.C.P.C.; Katz, Joel Ph.D.; Abbas, Sherif M.D.; Graham, Brent M.D., F.R.C.S.C.; Nova, Hugo M.D.; Rawson, Regan R.N.; Anastakis, Dimitri J. M.D., F.R.C.S.C., F.A.C.S.; von Schroeder, Herbert M.D., F.R.C.S.C.
Anesthesiology 2004; 101:461-7.

Background: The purpose of this study was to determine whether either regional anesthesia (RA) or general anesthesia (GA) provided the best analgesia with the fewest adverse effects up to 2 weeks after ambulatory hand surgery.
Methods: Patients undergoing ambulatory hand surgery were randomly assigned to RA (axillary brachial plexus block; n = 50) or GA (n = 50). Before surgery, all patients rated their hand pain (visual analog scale) and pain-related disability (Pain-Disability Index). After surgery, eligibility for bypassing the postanesthesia care unit ("fast track") was determined, and pain, adverse effects, and home-readiness scores were measured. On postoperative days 1, 7, and 14, patients documented their pain, opioid consumption, adverse effects, Pain-Disability Index, and satisfaction.
Results: More RA patients were fast-track eligible (P < 0.001), whereas duration of stay in the postanesthesia care unit was shorter in the RA group (P < 0.001). Time to first analgesic request was longer in the RA group (P < 0.001), and opioid consumption was reduced before discharge (P < 0.001). In the RA group, the pain ratings measured at 30, 60, 90, and 120 min after surgery were lower (P < 0.001), and patients spent less time in the hospital after surgery (P < 0.001). More GA patients experienced nausea/vomiting during recovery in the hospital (P < 0.05). However, on postoperative days 1, 7, and 14, there were no differences in pain, opioid consumption, adverse effects, Pain-Disability Index, or satisfaction.
Conclusions: Despite significant reduction in pain before discharge from the hospital after ambulatory hand surgery, single-shot axillary brachial plexus block does not reduce pain at home on postoperative day 1 or up to 14 days after surgery when compared with GA. However, RA does provide other significant early benefits, including reduction in nausea and faster discharge from the hospital.

Anesthetic Requirement Is Increased in Redheads.
Liem, Edwin B. M.D. ; Lin, Chun-Ming M.D. ; Suleman, Mohammad-Irfan M.D. ; Doufas, Anthony G. M.D., Ph.D.; Gregg, Ronald G. Ph.D. [S]; Veauthier, Jacqueline M. Ph.D. ; Loyd, Gary M.D. ; Sessler, Daniel I. M.D.
Anesthesiology 2004;101:279-83

Background: Age and body temperature alter inhalational anesthetic requirement; however, no human genotype is associated with inhalational anesthetic requirement. There is an anecdotal impression that anesthetic requirement is increased in redheads. Furthermore, red hair results from distinct mutations of the melanocortin-1 receptor. Therefore, the authors tested the hypothesis that the requirement for the volatile anesthetic desflurane is greater in natural redheaded than in dark-haired women.
Methods: The authors studied healthy women with bright red (n = 10) or dark (n = 10) hair. Blood was sampled for subsequent analyses of melanocortin-1 receptor alleles. Anesthesia was induced with sevoflurane and maintained with desflurane randomly set at an end-tidal concentration between 5.5 and 7.5%. After an equilibration period, a noxious electrical stimulation (100 Hz, 70 mA) was transmitted through bilateral intradermal needles. If the volunteer moved in response to stimulation, desflurane was increased by 0.5%; otherwise, it was decreased by 0.5%. This was continued until volunteers "crossed over" from movement to nonmovement (or vice versa) four times. Individual logistic regression curves were used to determine desflurane requirement (P50). Desflurane requirements in the two groups were compared using Mann-Whitney nonparametric two-sample test; P < 0.05 was considered statistically significant.
Results: The desflurane requirement in redheads (6.2 vol% [95% CI, 5.9-6.5]) was significantly greater than in dark-haired women (5.2 vol% [4.9-5.5]; P = 0.0004). Nine of 10 redheads were either homozygous or compound heterozygotes for mutations on the melanocortin-1 receptor gene.
Conclusions: Red hair seems to be a distinct phenotype linked to anesthetic requirement in humans that can also be traced to a specific genotype.

ACTA ANAESTHESIOLOGICA SCANDINAVICA - TOP

Influence of formulation on propofol pharmacokinetics and pharmacodynamics in anesthetized patients
R. Calvo, S. Telletxea, N. Leak, L. Aguilera, E. Suarez, L. De La Fuente, A. Martin-Suarez and J. C. Lukas
Acta Anaesthesiologica Scandinavica 2004; 48; 1038-48

Background:  In anesthesia with propofol, variability persists besides sophisticated effect targeting. Drug formulation may be another factor. We have analyzed, retrospectively, the pharmacokinetics (PK) and pharmacodynamics (PD) in monitored surgery patients anesthetized with one each of five formulations of propofol.
Methods: Propofol 1% ('form' 1: Diprivan^®(Zeneca Limited, Macclesfield, UK), 2: Recofol^® (Schering Espaa, Madrid, Spain), 3: Ivofol^® (Juste, Madrid, Spain), 4: Propofol Abbott^® (Abbott Laboratories, Madrid, Spain), 5: Fresenius^® (Fresenius Kabi Espaa, Barcelona, Spain)) was administered to 77 ASA I-II patients of age [mean (range) 44 (18-65) years]. Induction of anesthesia was with varying propofol doses up to endpoints of either 60 on the Bispectral Index system (BIS) in group I (n = 48, model development) or standard clinical signs in group II (n = 29, validation). Maintenance was with three 10-min infusions of 10, 8 and 6 mg kg^-1 h^-1. Three blood samples were obtained from each subject, immediately after induction, and at 15 and 30 min on maintenance, with BIS and hemodynamic variables recorded at these times also. Total and free blood concentrations (Cb) of propofol were determined with HPLC. Pharmacokinetic and PD models with link equilibration rate k_e0, were studied with a mixed-effects procedure (NONMEM).
Results: The induction dose (group I) showed large interindividual variability [mean (range) 163 (90-290 mg)] that correlated significantly with age, basal systolic blood pressure and formulation. The PK of propofol (basic model) was described by a one-compartment model with (typical value [interindividual coefficient of variation percent (CV%)]) CL=2.30 l min^-1 (27%) and V=8.40 l (80%). Weight (WT) and formulation, within NONMEM, were found to be significant covariates for CL and V, reducing their CV% to 25% and 74%, respectively. The final PK/PD model, which includes formulation, showed a 50% reduction in the CV% for both the k e0 and the residual error. This PK/PD model was validated in group II with 33% precision and no bias.
Conclusion: The PK and PD are not equal for all formulations, which contributes to an increase in variability of the observed effect.

Changes in visual and auditory response time during conscious sedation with propofol
K. M. Kim, W. J. Jeon, D. H. Lee, W. C. Kang, J. H. Kim, and G. J. Noh
Acta Anaesthesiologica Scandinavica 2004; 48; 1033-7

Background:  Using a push-button device, we investigated whether visual or auditory response time would increase with increasing sedation, and assessed the responsiveness score of the Observer's Assessment of Alertness/Sedation (OAA/S) scale at the point of first loss of response to visual or auditory stimulation.
Methods:  In experiment 1 we applied visual and auditory stimulation to 19 patients as the propofol target plasma concentration (C_PT) was increased to determine whether the visual or auditory response would be lost first. Thirty patients were each then infused with propofol, starting at a C_PT of 0.3 µg ml^-1 and increasing by increments of 0.2 µg ml^-1, during which visual (experiment 2) or auditory (experiment 3) stimulation was applied when the effect-site concentration (C_E) of propofol reached C_PT. Visual response time (VRT), auditory response time (ART), C_E and total amounts of propofol, and OAA/S score at the first loss of visual/auditory response were measured.
Results:  Visual response disappeared earlier than auditory response in 84.2% of the patients. Visual response time and ART were linearly prolonged as the C_E of propofol increased. The C_E and total amounts of propofol at the first loss of visual response were 1.2 ± 0.4 µg ml^-1 and 57.9 ± 16.7 mg, compared with 1.4 ± 0.5 µg ml^-1 and 71.6 ± 26.1 mg, respectively, at the first loss of auditory response. The median (range) OAA/S scores at the first loss of visual and auditory response were 4 (3-4) and 3 (2-4), respectively.
Conclusion:  VRT and ART were linearly prolonged with increasing sedation. Visual response may be useful in monitoring conscious sedation.

Is the ARX index a more sensitive indicator of anesthetic depth than the bispectral index during sevoflurane/nitrous oxide anesthesia?
T. Nishiyama, T. Matsukawa and K. Hanaoka
Acta Anaesthesiologica Scandinavica 2004; 48; 1028-32

Background : During general anesthesia, hypnotic components have been monitored with electroencephalogram. The bispectral index is derived from a cortical electroencephalogram, but the A-line ARX index is the electroencephalographic response to auditory stimuli. The purpose of this study was to compare the changes of the A-line ARX index and the bispectral index during sevoflurane - nitrous oxide anesthesia.
Methods:  One hundred females aged 30-60 years, and scheduled for partial mastectomy, were divided into two groups. Anesthesia was induced with sevoflurane 5% and nitrous oxide in oxygen for 3 min. A laryngeal mask airway was inserted, and anesthesia was maintained with sevoflurane 1-2% and nitrous oxide in oxygen. During surgery, the sevoflurane end-tidal concentration was kept at 0.5%, 1%, or 2% for 5 min before each measurement. Blood pressure, heart rate, and the A-line ARX index (n = 50), and the bispectral index (n = 50) were measured.
Results:  Blood pressure and heart rate increased following laryngeal mask airway insertion and blood pressure decreased at 2% sevoflurane in both groups similarly. The A-line ARX index, but not the bispectral index, increased significantly by laryngeal mask airway insertion and skin incision. The A-line ARX index decreased at 2% sevoflurane compared with 0.5%, while the bispectral index remained unchanged.
Conclusion:  During sevoflurane-nitrous oxide anesthesia, the A-line ARX index might be a more sensitive indicator of anesthetic depth than the bispectral index

BRITISH JOURNAL OF ANAESTHESIA - TOP

Effect of intraoperative intravenous crystalloid infusion on postoperative nausea and vomiting after gynaecological laparoscopy: comparison of 30 and 10 ml kg^-1
J. J. Magner, C. McCaul, E. Carton, J. Gardiner and D. Buggy
British Journal of Anaesthesia 2004 93(3):381-385

 Background. I.V. fluid administration has been shown to reduce postoperative nausea and vomiting (PONV). The optimum dose is unknown. We tested the hypothesis that administration of i.v. crystalloid of 30 ml kg^-1 would reduce the incidence of PONV compared with 10 ml kg^-1 of the same fluid.
Methods. A total of 141 ASA I female patients undergoing elective gynaecological laparoscopy were randomized, in double-blind fashion, to receive either 10 ml kg^-1 (n=71; CSL-10 group) or 30 ml kg^-1 (n=70; CSL-30 group) of i.v. compound sodium lactate (CSL).
Results. In the first 48 h after anaesthesia, the incidence of vomiting was lower in the CSL-30 group than in the CSL-10 group (8.6% vs 25.7%, P=0.01). Anti-emetic use was less in the CSL-30 group at 0.5 h (2.9% vs 14.3%, P=0.04). The incidence of severe nausea was significantly reduced in the treatment group at awakening (2.9% vs 15.7%, P=0.02), 2 h (0.0% vs 8.6%, P=0.04) and cumulatively (5.7% vs 27.1%, P=0.001). The numbers needed to treat to prevent vomiting, severe nausea and antiemetic use in the first 48 h were 6, 5 and 6, respectively.
Conclusion. I.V. administration of CSL 30 ml kg^-1 to healthy women undergoing day-case gynaecological laparoscopy reduced the incidence of vomiting, nausea and anti-emetic use when compared with CSL 10 ml kg^-1.

Applicability of risk scores for postoperative nausea and vomiting in adults to paediatric patients
L. H. J. Eberhart, A. M. Morin, D. Guber, F. J. Kretz, A. Schäuffelen, H. Treiber, H. Wulf and G. Geldner
British Journal of Anaesthesia 2004 93(3):386-392

Background. Scores to predict the occurrence of postoperative vomiting (PV) or nausea and vomiting (PONV) are well established in adult patients. The aim of this survey was to evaluate the applicability of risk scores developed and tested in adult patients in 983 paediatric patients (0–12 yr) undergoing various surgical procedures.
Method. The predictive properties of five models were compared with respect to discriminating power (measured by the area under a receiver operating characteristic curve) and calibration (comparison of the predicted and the actual incidences of the disease by weighed linear regression analysis).
Results. The cumulative incidence of PV was 33.2% within 24 h. The discriminating power was low and insufficient in all models tested (0.56–0.65). Furthermore, the predicted incidences of the scores correlated only vaguely with the actual incidences observed.
Conclusion. Specialized scores for children are required. These might use the history of PV, strabismus surgery, duration of anaesthesia ≥45 min, age ≥5 yr and administration of postoperative opioids as independent risk factors.

CANADIAN JOURNAL OF ANESTHESIA - TOP

Induction with sevoflurane-remifentanil is comparable to propofol-fentanyl-rocuronium in PONV after laparoscopic surgery
Homer Yang, MD FRCPC, Peter T.-L. Choi, MD FRCPC, James McChesney, MB CHB FRCPC and Norman Buckley, MD FRCPC
Canadian Journal of Anesthesia 51:660-667 (2004)

Purpose: To compare sevoflurane-remifentanil induction and propofol-fentanyl-rocuronium induction with regards to the frequency of moderate to severe postoperative nausea and vomiting (PONV) in the first 24 hr after laparoscopic day surgery.
Methods: After informed consent, 156 ASA physical status class I to III patients undergoing laparoscopic cholecystectomy or tubal ligation were randomized to either induction with sevoflurane 8%, N₂O 67% and iv remifentanil 1 to 1.5 µg·kg^-1 or induction with iv fentanyl 2 to 3 µg·kg^-1, propofol 2 mg·kg^-1, and rocuronium 0.3 to 0.5 mg·kg^-1. All patients received iv ketorolac 0.5 mg·kg^-1 at induction and sevoflurane-N₂O maintenance anesthesia with rocuronium as needed. PONV was treated with iv ondansetron, droperidol, or dimenhydrinate; postoperative pain was treated with opioid analgesics. Patients were followed for 24 hr with regards to PONV and pain. Intubating conditions, induction and emergence times, time to achieve fast-track discharge criteria, and drug costs were measured.
Results: No differences were seen between the two groups in their frequencies of 24-hr moderate to severe PONV and postoperative pain, or in their intubating conditions, induction and emergence times, and time to achieve fast-track discharge criteria. Patients undergoing sevoflurane-remifentanil induction received more morphine (11 mg vs 8 mg; P < 0.001) in the postanesthetic care unit. Sevoflurane-remifentanil induction resulted in similar anesthetic and total drug costs for both procedures.
Conclusion: We did not demonstrate any difference in PONV, pain, or anesthetic/recovery times or costs between the sevoflurane and propofol groups. Sevoflurane-remifentanil induction is a feasible technique for anesthetic induction.

Intrathecal lidocaine and sufentanil shorten postoperative recovery after outpatient rectal surgery
Beverly Waxler, MD, Shirley A. Mondragon, MS CRNA, Sonal N. Patel, MD and Kochuthresia Nedumgottil, MD
Canadian Journal of Anesthesia 51:680-684 (2004)

Purpose: A short recovery time for same day surgery is important to the patient and the hospital. A prospective, randomized, double-blinded study in the postanesthetic care unit was designed to compare the recovery time from spinal anesthesia with low-dose intrathecal (IT) lidocaine and sufentanil to that with IT lidocaine alone. The incidence of adverse effects was also assessed.
Methods: Forty-nine patients (ASA I–III, age 20–69 yr) underwent spinal anesthesia for rectal surgery. The patients were randomized into two groups. One group (n = 28) received low-dose IT lidocaine (15 mg) and sufentanil (10 µg) and the other group (n = 21) received IT lidocaine (50 mg). The time to ambulation, the incidence of pruritus, and other variables were recorded. Statistical difference was assumed if P < 0.05.
Results: Our results show a significantly shorter ambulation time (120 ± 26 min) after IT low-dose lidocaine (15 mg) and 10 µg sufentanil vs 50 mg IT lidocaine (162 ± 32 min, P < 0.0001). Patients who received IT lidocaine and sufentanil recovered faster. Fifty percent of the patients who received IT sufentanil suffered from pruritus.
Conclusion: IT lidocaine (15 mg) and sufentanil resulted in a shorter time to ambulation compared to IT lidocaine (50 mg) alone and provided excellent anesthesia despite its disadvantage of pruritus.  

Caudal neostigmine with bupivacaine produces a dose-independent analgesic effect in children
Rajesh Mahajan , MD, Vinod K. Grover, MD MNAMS and Pramila Chari, MD FAMS
Canadian Journal of Anesthesia 51:702-706 (2004)

Purpose: To evaluate the analgesic efficacy and duration of varying doses of caudal neostigmine with plain bupivacaine and its side effects in children undergoing genito-urinary surgery.
Methods: In a randomized double-blind prospective study 80 boys aged two to eight years scheduled for surgical repair of hypospadias were allocated randomly to one of four groups (n = 20 each) and received either only caudal 0.25% plain bupivacaine 0.5 mL·kg^-1 (Group I) or 0.25% plain bupivacaine 0.5 mL·kg^-1 with neostigmine (Groups II–IV) in doses of 2, 3 and 4 µg·kg^-1 respectively. Postoperative pain was assessed for 24 hr using an objective pain score. Blood pressure, heart rate, oxygen saturation, total amount of analgesic consumed and adverse effects were also recorded.
Results: The duration of postoperative analgesia in Group I (5.1 ± 2.3 hr) was significantly shorter than in the other three groups (II –16.6 ± 4.9 hr; III – 17.2 ± 5.5 hr; IV – 17.0 ± 5.8 hr; P < 0.05). Total analgesic (paracetamol) consumption was significantly more in Group I (697.6 ± 240.7 mg) than in the groups receiving caudal neostigmine (II – 248.0 ± 178.4; III – 270.2 ± 180.8 and IV –230.6 ± 166.9 mg; P < 0.05). Groups II, III and IV were comparable with regards to duration of postoperative analgesia and total analgesic consumption (P > 0.05). Incidence of nausea and vomiting were comparable in all four groups. No significant alteration in vital signs or any other adverse effects were observed.
Conclusions: Caudal neostigmine (2, 3 and 4 µg·kg^-1) with bupivacaine produces a dose-independent analgesic effect (~16–17 hr) in children as compared to those receiving caudal bupivacaine alone (approximately five hours) and a reduction in postoperative rescue analgesic consumption without increasing the incidence of adverse effects.

Neuromuscular blockade does not change the incidence or severity of pharyngolaryngeal discomfort after LMA anesthesia
Thomas M. Hemmerling, MD DEAA, Pierre Beaulieu, MD PhD, Klaus E. Jacobi, MD , Denis Babin, MSc and Joachim Schmidt, MD
Canadian Journal of Anesthesia 51:728-732 (2004)

Purpose: Positive pressure ventilation using a laryngeal mask airway (LMA) has gained increased popularity. This study examined the influence of neuromuscular blockade on the incidence and severity of pharyngolaryngeal discomfort after positive pressure ventilation using a LMA.
Methods: 130 patients were included in this prospective, double-blind, randomized two-centre study. Anesthesia was induced with remifentanil and propofol and maintained using remifentanil and sevoflurane in 30% oxygen and 70% air. Patients were mechanically ventilated at 15 breaths·min^-1 with tidal volumes to maintain PETCO₂ 30–40 mmHg. Patients were randomly assigned to receive no neuromuscular blocking agent (NOBLOCK group) or cisatracurium prior to LMA insertion (BLOCK group). Prior to the end of surgery, morphine 3 to 5 mg iv were injected. The ease of insertion of the LMA, cuff pressure, and inspiratory pressure were recorded. Patients were asked immediately after two hours, and 24 hr after surgery to rate sore throat, dysphonia, or dysphagia as absent, minimal, moderate or severe. Continuous and categorical data were compared using t test and Chi-squared test, respectively.
Results: 68 and 62 patients were randomized to the NOBLOCK and BLOCK groups, respectively. Successful insertion on first attempt were 89% and 92% in the NOBLOCK and BLOCK groups, respectively. Mean intracuff and inspiratory pressures were 85 ± 35 mmHg and 13 ± 3 mmHg for the NOBLOCK group, and 96 ± 34 mmHg and 15 ± 2 mmHg for the BLOCK group. The immediate, two and 24 hr postoperative incidences and severity of sore throat, dysphonia, and dysphagia did not differ significantly between the two groups.
Conclusion: Neuromuscular blockade does not influence the ease or rate of success of LMA insertion nor the incidence and severity of pharyngolaryngeal discomfort after positive pressure ventilation using a LMA.

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Low doses of rocuronium during remifentanil-propofol-based anesthesia in children: comparison of intubating conditions
Oztekin S, Hepaguslar H, Kilercik H, Kar AA, Boyaci F, Elar Z.
Paediatr Anaesth. 2004 Aug;14(8):636-41.

Background: In this prospective double-blind study, intubation conditions were compared at 90 s following two different low doses of rocuronium during remifentanil and propofol anesthesia in children undergoing ambulatory procedures.
Methods: Forty-four children (ASA I-II, aged 3-12 years) undergoing day case ENT surgery were premedicated with midazolam 0.5 mg. kg^-1. Following atropine 10 microg.kg^-1, remifentanil infusion 0.5 microg.kg^-1.min^-1 was started. After 60s, anesthesia was induced with propofol 2.5 mg.kg^-1. Immediately after a bolus dose of propofol, the children received rocuronium doses of 0.15 mg.kg^-1 (group I, n = 22) or 0.3 mg.kg^-1 (group II, n = 22) in a randomized manner, after which an infusion of propofol 6 mg.kg^-1 h^-1 was added to the infusion of remifentanil 0.5 microg.kg^-1 min^-1 for maintenance of anesthesia. Intubating conditions were evaluated 90 s after rocuronium administration applying the Copenhagen Scoring System which included components of laryngoscopy, vocal cord movement and reaction to intubation. Hemodynamic values were recorded at predetermined time intervals.
Results: Excellent, good and poor intubation conditions were 18.2, 40.9 and 40.9% in group I and 40.9, 54.5 and 4.5% in group II. Clinically acceptable intubating conditions (excellent and good) were significantly higher in group II (95.5%) than in group I (59.1%) (P = 0.004). Mean values of heart rate and blood pressure did not differ significantly between groups. No children required any intervention for hemodynamic instability and/or muscle rigidity.
Conclusions: The results suggest that 0.3 mg.kg^-1 of rocuronium may be a better low dose than 0.15 mg.kg^-1 of rocuronium for clinically acceptable intubating conditions in pediatric ambulatory surgery during remifentanil-propofol-based anesthesia at the doses used in the study.

Minimum effective dose of dexamethasone after tonsillectomy.
Celiker V, Celebi N, Canbay O, Basgul E, Aypar U.
Paediatr Anaesth. 2004 Aug;14(8):666-9.

Background: The minimum effective dose of dexamethasone in conjunction with 50 microg.kg^-1 ondansetron was evaluated in the treatment for vomiting after elective tonsillectomy or adenotonsillectomy.
Methods: A total of 102 healthy children between 2 and 12 years of age participated in this prospective, randomized, double-blind study. A single intravenous (i.v.) dose of dexamethasone (50, 100, 150 microg.kg^-1, maximum dose 8 mg) with ondansetron (50 microg.kg^-1) was administered just before the end of surgery. Equal volumes of normal saline were given to the control group. General anaesthesia was induced and maintained by inhalation of N₂O/O₂ and sevoflurane. All other preoperative and postoperative medications (including a supplementary dose of antiemetics if necessary), anaesthesia and surgical techniques were standardized.
Results: No significant differences were observed between groups in postoperative vomiting on the day of surgery and the next day, or in the need for postoperative pain medication and supplementary doses of antiemetics (P > 0.05).
Conclusions: These results indicate that surgical technique and anaesthetic management used in this study could be the cause of the lower incidence of nausea and vomiting. Assessment of nausea and vomiting in a prospective study with larger groups of patients may reflect different results.

A comparison of postoperative sore throat after use of laryngeal mask airway and tracheal tube.
Mizutamari E, Yano T, Ushijima K, Ito A, Anraku S, Tanimoto H, Terasaki H.
J Anesth. 2004;18(3):151-7.

PURPOSE: We compared the degree of postoperative sore throat (PST) after use of a laryngeal mask airway (LMA; by two insertion techniques) and a tracheal tube (TT) in adult patients.
METHODS: Eighty-six adult patients undergoing surgery of an extremity were randomized into three groups. The LMAs (size 4 for men, 3 for women) and TTs were lubricated with 2% lidocaine gel. After the induction of anesthesia, an LMA with the cuff deflated was inserted and then the cuff was inflated in group A, an LMA with the cuff inflated was inserted in group B, and the trachea was intubated using vecuronium in group C; staff anesthesiologists performed all these methods. LMA cuffs were inflated with the maximum recommended volume of air. TT cuffs were inflated with the minimum volume of air without gas leakage at 20 cm H₂O pressure. The mode of ventilation depended on the individual anesthesiologists. Blood traces on the devices were examined after their removal. PST was rated immediately after anesthesia and on the first postoperative day, using a three-point score and a 100-mm visual analog scale, respectively.
RESULTS: Most of the patients receiving an LMA breathed spontaneously and those receiving a TT underwent controlled ventilation. The ratio of positive blood traces on devices, as well as the degree of PST immediately after anesthesia, was similar in the three groups; however, on the first postoperative day, the severity of PST was greater in the LMA groups than in the TT group ( P = 0.016). The severity of PST was similar with the two LMA insertion techniques.
CONCLUSION: In the conditions of our study, LMAs inserted with the cuff either fully inflated or deflated worsened PST compared with TTs.
 

Patients' perception of pain during axillary and humeral blocks using multiple nerve stimulations.
Koscielniak-Nielsen ZJ, Rasmussen H, Nielsen PT.
Reg Anesth Pain Med. 2004 Jul-Aug;29(4):328-32.

Background and objectives Axillary or humeral blocks by multiple nerve stimulation (MNS) are used for ambulatory hand surgery. This double-blind study identified which of the three main components of the procedure (repeated needle passes, local anesthetic injections, or electrical stimulations) is most painful, quantified its intensity, and recorded patients' preferences for a future anesthetic.
Methods Eighty unsedated ambulatory patients were randomized to 2 equal groups: axillary (A) and humeral (H). In each patient, 4 terminal motor nerves (musculocutaneous, median, ulnar, and radial) were electrolocated by use of an initial current of 2 mA, 0.1 ms and a target current of 0.1 to 0.5 mA. After block placement and before the start of surgery, patients were requested to identify which of the 3 main components of the block was most unpleasant and to quantify its intensity on a visual analog scale (VAS) of 0 to 100. Twenty minutes after completion of the block, the unblocked nerves were electrolocated at the elbow and supplemented. Patients were declared ready for surgery when they had complete analgesia of the hand and forearm. Before discharge from the hospital, patients indicated which anesthetic method (block alone, block plus sedation, or general anesthesia) they would choose for future hand surgery.
Results Twenty-seven patients in group A vs. 17 patients in group H reported electrical stimulations as the most unpleasant block component (P =.03). No significant differences occurred in any of the VAS scores. Patients' request for the same anesthetic, 35 in group A and 37 in group H, were similar. Group A patients were ready for surgery sooner than group H patients (mean 26 minutes vs. mean 30 minutes for group H patients; P =.04). No serious complications were observed.
Conclusions This study found that more axillary-block patients compared with humeral-block patients reported electrical stimulation as the most unpleasant part of the block but failed to detect significant differences in the intensity of the 3 block components (repeated needle passes, local anesthetic injections, and electrical stimulations). Most patients in both groups would accept the same block for future hand operations. Patients were ready for surgery sooner after axillary block, but the clinical importance of this finding is doubtful.

A randomised controlled trial of paediatric conscious sedation for dental treatment using intravenous midazolam combined with inhaled nitrous oxide or nitrous oxide/sevoflurane.
Averley PA, Girdler NM, Bond S, Steen N, Steele J.
Anaesthesia. 2004 Sep;59(9):844-52.

Summary Failure of dental treatment due to anxiety is a common problem in children. The aim of this study was to establish whether the use of a combination of intravenous midazolam with inhalation agents (nitrous oxide alone or in combination with sevoflurane) was any more likely to result in successful completion of treatment than midazolam alone. A further aim was to evaluate the clinical viability of these techniques as an alternative to general anaesthesia. In total, 697 children too anxious for management with relative analgesia and requiring invasive dental procedure for which a general anaesthetic would usually be required, were recruited and randomly assigned to one of three groups given the following interventions: group 1 - a combination of inhaled medical air and titrated intravenous midazolam, group 2 - a combination of inhaled 40% nitrous oxide in oxygen and titrated intravenous midazolam, and group 3 - a combination of an inhaled mixture of sevoflurane 0.3% and nitrous oxide 40% in oxygen with titrated intravenous midazolam. The primary outcome measure was successful completion of the intended dental treatment with a co-operative child responsive to verbal commands. In group 1, 54% (94/174 children) successfully completed treatment. In group 2, 80% (204/256 children) and in group 3, 93% (249/267 children) completed treatment. This difference was significant at the 1% level. Intravenous midazolam, especially in combination with inhaled nitrous oxide or sevoflurane and nitrous oxide, are effective techniques, with the combination of midazolam and sevoflurane the one most likely to result in successful treatment.
 

A partially blinded randomised controlled trial of patient-maintained propofol sedation and operator controlled midazolam sedation in third molar extractions.
Leitch JA, Anderson K, Gambhir S, Millar K, Robb ND, McHugh S, Kenny GN
Anaesthesia. 2004 Sep;59(9):853-60.

Summary Patient-maintained sedation using propofol has recently been shown to be effective for dental surgery. We compared this new technique to the established technique of operator administered midazolam. The two groups were compared before, during and after sedation. The two primary outcomes were time until discharge and oxygen saturation. Vital signs, anxiety and psychomotor skills were also compared. State anxiety was reduced to a greater extent in the propofol group (mean difference 10 (SD 4) mm; p = 0.010. Propofol patients recovered quicker (mean difference 7 (SD 1.4) min; p = 0.001). Propofol patients had a smaller reduction in arterial oxygen saturation (mean difference 0.8 (SD 0.3)%; p = 0.030), and a reduced increase in heart rate (mean difference 9 (SD 2) beats.min^-1; p < 0.001). Both techniques were well tolerated and safe. Propofol sedation offered superior anxiolysis, quicker recovery, less amnesia and less depression of simple psychomotor function.

Cefazolin tolerance does not predict ceftriaxone hypersensitivity: unique side chains precipitate anaphylaxis.
Poston SA, Jennings HR, Poe KL.
Pharmacotherapy. 2004 May;24(5):668-72.

A 48-year-old woman with a questionable history of an unspecified ceftriaxone allergy was treated with cefazolin for surgical antibiotic prophylaxis. After she tolerated cefazolin therapy for 4 days, the medical staff concluded that her allergy history was inaccurate, and she was treated with intravenous ceftriaxone for suspected nosocomial pneumonia. Approximately 10 minutes after the start of the infusion, the patient experienced anaphylaxis. Initial symptoms of oral angioedema and laryngopharyngeal constriction progressed to dyspnea, tachypnea, hypotension, and tachycardia, all of which quickly resolved after immediate treatment with hydrocortisone, diphenhydramine, and epinephrine. Skin testing with cefazolin, cefepime, and ceftriaxone revealed that the likely allergic determinant mediating the patient's hypersensitivity reaction was the unique ceftriaxone R2 side chain and not the beta-lactam ring, which initially was suspected by the physician. Immunoglobulin E-mediated hypersensitivity reactions to cephalosporins may occur due to antibody complexes with the beta-lactam ring or various cephalosporin side chains. Misconceptions regarding the nature of cephalosporin allergies complicate antibiotic selection for patients with questionable allergy histories and may lead to inappropriate drug reexposure and anaphylaxis. Detailed understanding of the antigenic determinants that mediate hypersensitivity reactions is essential for clinicians to avoid type 1 reactions in patients with a suspected allergy to cephalosporins

Anesthetic considerations for pediatric outpatient surgery.
Emhardt, J. D., C. Saysana, et al.
Semin Pediatr Surg 2004; 13 (3): 210-21.

At least 60% of all pediatric surgical procedures are performed as outpatients. Successful outpatient practice requires that both the patients and the procedures are appropriate for outpatient management. Appropriate scheduling ensures that the overall function of the outpatient unit is not compromised. While not all scheduled patients need be perfectly healthy, care must be taken to provide adequate resources to those patients who are not, without diverting resources away from other patients. Anesthesia must be managed with attention to the unique physiologic and psychological challenges of children. Anesthetic management of postoperative nausea and vomiting and provision of adequate postoperative analgesia, including regional techniques, are important elements of the care plan.

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