Volume 4, Issue 12 S A M B A T A L K S - PAGE 3 May, 2005

FROM THE LITERATURE: - TOP


ANESTHESIA AND ANALGESIA - TOP

Peripheral Nerve Blocks Result in Superior Recovery Profile Compared with General Anesthesia in Outpatient Knee Arthroscopy
Admir Hadzic, MD, PhD, Pelin Emine Karaca, MD, Paul Hobeika, MD, George Unis, MD, Jeffrey Dermksian, MD, Marina Yufa, MD, Richard Claudio, BS, Jerry D. Vloka, MD, PhD, Alan C. Santos, MD, MPH, and Daniel M. Thys, MD
Anesth Analg 2005;100:976-981

It has been suggested that use of peripheral nerve blocks (PNBs) may have some potential benefits in the outpatient setting. There have been no studies specifically comparing PNBs performed with short-acting local anesthetics with general anesthesia (GA) in patients undergoing outpatient knee surgery. We hypothesized that a combination of lumbar plexus and sciatic blocks using a short-acting local anesthetic will result in shorter time-to-discharge-home as compared with GA. Patients scheduled to undergo knee arthroscopy were randomized to receive a GA (midazolam, fentanyl, propofol, N₂O/O₂/desflurane via laryngeal mask airway) or lumbar plexus/sciatic block (PNBs; 2-chloroprocaine). Patients given GA also received an intraarticular injection of 20 mL 0.25% bupivacaine for postoperative pain control. Patients in the PNB group were given midazolam (up to 4 mg) and alfentanil (500–750 µg) before block placement and propofol 30–50 µg • kg^-1 • min^-1 for intraoperative sedation. Relevant perioperative times, postanesthesia care unit bypass rate, severity of pain, and incidence of complications were compared between the two groups. Fifty patients were enrolled in the study; 25 patients each received GA or PNBs. Total operating room time did not differ significantly between the 2 groups (97 ± 37 versus 91 ± 42 min). Seventy-two percent of patients receiving PNB met criteria enabling them to bypass Phase I postanesthesia care unit compared with only 24% of those receiving GA (P < 0.002). Time to meet criteria for discharge home (home readiness) and time to actual discharge were significantly shorter for patients given PNBs than for patients given GA (131 ± 62 versus 205 ± 94 and 162 ± 71 versus 226 ± 96, respectively). Under the conditions of our study, the combination of lumbar plexus and sciatic blocks with 2-chloroprocaine 3% was associated with a superior recovery profile compared with GA in patients having outpatient knee arthroscopy.

Preventing the Withdrawal Response Associated with Rocuronium Injection: A Comparison of Fentanyl with Lidocaine
Norezalee Ahmad, MBChB, MMed, Choy Yin Choy, MBChB, MMed, FANZCA, Esa Ab Aris, MD, MMed, and Subrahmanyam Balan, MBBS, MMed
Anesth Analg 2005;100:987-990

We compared the efficacy of IV fentanyl with IV lidocaine as pretreatment for the prevention of withdrawal response after rocuronium injection. For this prospective, randomized, placebo-controlled, double-blind study we recruited 90 patients aged between 18 and 65 yr, ASA physical status I or II, who had undergone elective surgery requiring general anesthesia and positive pressure ventilation. Patients were randomly allocated to 1 of 3 groups: group F received 2 mL IV fentanyl 50 µg/mL (100 µg), group L received 2 mL of preservative-free lidocaine 2% (40 mg), and group P (placebo) received 2 mL of normal saline. The incidence of withdrawal response after rocuronium was 57%, 30%, and 7% in the placebo, lidocaine, and fentanyl groups, respectively. We found a significant reduction in incidence of withdrawal response in both the fentanyl and lidocaine groups when compared with the placebo group (P < 0.05), with the fentanyl group being most effective (P < 0.05). In conclusion, both fentanyl and lidocaine are effective clinical treatments to alleviate the withdrawal response associated with rocuronium injection, with fentanyl being more effective.

A Comparison of Sevoflurane-Propofol Versus Sevoflurane or Propofol for Laryngeal Mask Airway Insertion in Adults
Sahar M Siddik-Sayyid, MD, FRCA, Marie T. Aouad, MD, Samar K. Taha, MD, Dima G. Daaboul, MD, Patricia G. Deeb, MD, Faraj M. Massouh, MD, Marie-Rose A. Muallem, MD, and Anis S. Baraka, MD, FRCA
Anesth Analg 2005;100:1204-1209

In a prospective, randomized study, we investigated the incidence of successful insertion of laryngeal mask airway (LMA) at the first attempt and the incidence of side effects after LMA insertion using the combination of sevoflurane and propofol as compared with either sevoflurane or propofol alone for induction of anesthesia. Eighty-three unpremedicated ASA physical status I–II patients were anesthetized with a single vital capacity breath (VCB) of sevoflurane 8% supplemented with IV propofol 1.5 mg/kg, a single VCB of sevoflurane 8%, or IV propofol 3 mg/kg. The coinduction technique was associated with the most frequent incidence of successful LMA insertion at the first attempt (93.5%) than either sevoflurane alone (46%) or propofol alone (61.5%) (P < 0.001). Propofol-induced induction of anesthesia allowed the fastest insertion of LMA and was associated with the least frequent incidence of postoperative nausea and vomiting. However, this advantage of propofol was offset by a frequent incidence of pain on injection (69%) and the occurrence of movements during insertion of the LMA (50% in the propofol group versus 19% and 26% in the sevoflurane and sevoflurane-propofol groups, respectively; P < 0.05), as well as a more frequent incidence of apnea (84% in the propofol group versus 7% and 16% in the sevoflurane and sevoflurane-propofol groups, respectively; P < 0.001). The report shows that induction of anesthesia with sevoflurane-propofol combined provides a frequent incidence of successful LMA insertion at the first attempt that is associated with an infrequent incidence of apnea.

The Endoscopically Measured Effects of Airway Maneuvers and the Lateral Position on Airway Patency in Anesthetized Children with Adenotonsillar Hypertrophy
Young-Chang P. Arai, MD, Kayo Fukunaga, MD, Wasa Ueda, MD, Masashi Hamada, MD, Hiroyuki Ikenaga, MD, and Kei Fukushima, MD
Anesth Analg 2005;100:949-952

Obstruction of the upper airway is a major challenge for anesthesiologists administering general anesthesia in spontaneously breathing children with adenotonsillar hypertrophy. Lateral positioning is a simple treatment for obstructive sleep apnea. In this study, we examined the effects of body position shifting and common airway maneuvers such as chin lift and jaw thrust on airway patency (stridor score and upper airway dimensions by endoscopy) in anesthetized children scheduled for adenotonsillectomy. Eighteen children aged 1–11 yr were anesthetized with sevoflurane. During spontaneous breathing with 5% sevoflurane and 100% oxygen, upper airway dimensions and stridor score were recorded. After baseline recording, chin lift and jaw thrust were performed in both the supine and the lateral decubitus position. Chin lift, jaw thrust, and lateral position increased the airway dimensions and improved the stridor score. Moreover, lateral positioning enhanced the effects of these airway maneuvers on airway patency. We concluded that lateral positioning combined with airway maneuvers provided better airway patency for anesthetized children with adenotonsillar hypertrophy.

Recovery After Anesthesia for Short Pediatric Oncology Procedures: Propofol and Remifentanil Compared with Propofol, Nitrous Oxide, and Sevoflurane
Hilary R. Glaisyer, MRCP, FRCA, and Michael R. J. Sury, FRCA
Anesth Analg 2005;100:959-963

Anesthesia techniques in children undergoing short painful oncology procedures should allow rapid recovery without side effects. We compared the recovery characteristics of two anesthetic techniques: propofol with sevoflurane and nitrous oxide and a total IV technique using propofol and remifentanil. Twenty-one children, undergoing two similar painful procedures within 2 wk were studied in a single-blind manner within patient comparison. The order of the techniques was randomized. Propofol and remifentanil involved bolus doses of both propofol 3–5 mg/kg and remifentanil 1–4 µg/kg. Propofol with sevoflurane and nitrous oxide involved propofol 3–5 mg/kg with 2%–8% sevoflurane and 70% nitrous oxide. The primary outcome variable was the time taken to achieve recovery discharge criteria; other recovery characteristics were also noted. The mean age of the children was 6.5 yr (range, 2.5–9.8 yr). Nineteen had lymphoblastic leukemia and two had lymphoma. All children had intrathecal chemotherapy and one had bone marrow aspiration. Most procedures lasted <4 min. The mean time to achieve recovery discharge criteria was appreciably shorter after propofol and remifentanil than propofol with sevoflurane and nitrous oxide by nearly 19 min (P = 0.001). All other time comparisons had similar trends and statistical differences. Seven parents expressed a preference for the propofol and remifentanil technique compared with one preferring propofol with sevoflurane and nitrous oxide. Children are apneic during the procedure and require respiratory support from an anesthesiologist. Discharge readiness from the recovery ward was achieved on average 19 min earlier after propofol with remifentanil compared with the combination of propofol, sevoflurane and nitrous oxide. Parents more often preferred propofol with remifentanil.

Perioperative Fluid Management and Clinical Outcomes in Adults
Michael P. W. Grocott, BSc, MRCP, FRCA, Michael G. Mythen, MD, FRCA, and Tong J. Gan, MD, FRCA, FFARCS(I)
Anesth Analg 2005;100:1093-1106

The administration of IV fluid to avoid dehydration, maintain an effective circulating volume, and prevent inadequate tissue perfusion should be considered, along with the maintenance of sleep, pain relief, and muscular relaxation, a core element of the perioperative practice of anesthesia. Knowledge of the effects of different fluids has increased in recent years, and the choice of fluid type in a variety of clinical situations can now be rationally guided by an understanding of the physicochemical and biological properties of the various crystalloid and colloid solutions available. However, there are few useful clinical outcome data to guide this decision. Deciding how much fluid to give has historically been more controversial than choosing which fluid to use. A number of clinical studies support the notion that an approach based on administering fluids to achieve maximal left ventricular stroke volume (while avoiding excess fluid administration and consequent impairment of left ventricular performance) may improve outcomes. In this article, we review the available fluid types and strategies of fluid administration and discuss their relationship to clinical outcomes in adults.

ANESTHESIOLOGY - TOP

Effects of Skin Pigmentation on Pulse Oximeter Accuracy at Low Saturation.
Bickler, Philip E. M.D., Ph.D. ; Feiner, John R. M.D. ; Severinghaus, John W. M.D.
Anesthesiology. 102(4):715-719, April 2005.

Background: It is uncertain whether skin pigmentation affects pulse oximeter accuracy at low HbO₂ saturation.
Methods: The accuracy of finger pulse oximeters during stable, plateau levels of arterial oxygen saturation (Sao₂) between 60 and 100% were evaluated in 11 subjects with darkly pigmented skin and in 10 with light skin pigmentation. Oximeters tested were the Nellcor N-595 with the OxiMax-A probe (Nellcor Inc., Pleasanton, CA), the Novametrix 513 (Novametrix Inc., Wallingford, CT), and the Nonin Onyx (Nonin Inc., Plymouth, MN). Semisupine subjects breathed air-nitrogen-carbon dioxide mixtures through a mouthpiece. A computer used end-tidal oxygen and carbon dioxide concentrations determined by mass spectrometry to estimate breath-by-breath Sao₂, from which an operator adjusted inspired gas to rapidly achieve 2- to 3-min stable plateaus of desaturation. Comparisons of oxygen saturation measured by pulse oximetry (Spo₂) with Sao₂ (by Radiometer OSM3) were used in a multivariate model to determine the interrelation between saturation, skin pigmentation, and oximeter bias (Spo₂ - Sao₂).
Results: At 60-70% Sao₂, Spo₂ (mean of three oximeters) overestimated Sao₂ (bias +/- SD) by 3.56 +/- 2.45% (n = 29) in darkly pigmented subjects, compared with 0.37 +/- 3.20% (n = 58) in lightly pigmented subjects (P < 0.0001). The SD of bias was not greater with dark than light skin. The dark-light skin differences at 60-70% Sao₂ were 2.35% (Nonin), 3.38% (Novametrix), and 4.30% (Nellcor). Skin pigment-related differences were significant with Nonin below 70% Sao2, with Novametrix below 90%, and with Nellcor at all ranges. Pigment-related bias increased approximately in proportion to desaturation.
Conclusions: The three tested pulse oximeters overestimated arterial oxygen saturation during hypoxia in dark-skinned individuals.

ACTA ANAESTHESIOLOGICA SCANDINAVICA - TOP

Effect of additives in lidocaine spray on postoperative sore throat, hoarseness and dysphagia after total intravenous anaesthesia
K. Hara and K. Maruyama
Acta Anaesthesiologica Scandinavica 2005; 49: 463 - 7

Background: Laryngo-tracheal lidocaine spray before intubation is associated with an increased risk of postoperative throat problems. Our study investigated the effect of additives contained in lidocaine spray on postoperative sore throat, hoarseness and dysphagia.
Methods: We compared the incidence and severity of postoperative throat complications after laryngo-tracheal application of lidocaine spray (40 mg), lidocaine (40 mg) or normal saline as placebo during laryngoscopy with total intravenous anaesthesia in 122 ASA I-III patients aged 15-87 years in a double-blinded, placebo-controlled study. The incidence and severity of postoperative sore throat, hoarseness and dysphagia were evaluated on the day of and the day after surgery.
Results: Sore throat and dysphagia were significantly more severe after lidocaine spray was used than after lidocaine or placebo was used. However, there was no significant difference in the incidence or severity of postoperative sore throat, hoarseness or dysphagia between the lidocaine group and the placebo group throughout the study.
Conclusion: These results suggest that additives in lidocaine spray, not lidocaine itself, contribute to the increase in postoperative throat problems. Therefore, lidocaine spray should be avoided to prevent these unnecessary complications. Our findings also confirm that laryngo-tracheal lidocaine application does not prevent sore throat, hoarseness or dysphagia after total intravenous anaesthesia.

Clonidine as an adjuvant for lidocaine in axillary brachial plexus block in patients with chronic renal failure
T. Adnan, A. A. Elif, K. Ay e and A. Gülnaz
Acta Anaesthesiologica Scandinavica 2005; 49: 563 - 8

Background: Clonidine is often used as an adjuvant for local anaesthetics in regional anaesthesia; however, its effects on axillary block in chronic renal failure patients have not been investigated. These effects were the focus of this study.
Methods: Twenty-eight adult chronic renal failure patients (ASA physical status III) scheduled for arteriovenous fistula construction were studied in a prospective, randomized, double-blind, controlled design. All axillary block procedures were performed by the same anaesthesiologist using the nerve stimulator technique. The control group received 40 ml of lidocaine (10 mg mL^-1) combined with 1 ml of saline, and the clonidine group received 40 ml of lidocaine (10 mg mL^-1) mixed with 150 µg of clonidine. Characteristics of the patients and the blocks were recorded, in addition to data on the nerves stimulated, intraoperative haemodynamic parameters, and sedative and analgesic requirements.
Results: The onset time for sensory blockade was longer in the clonidine group than in the controls (P = 0.013), and both motor and sensory blocks lasted longer in the clonidine group (P = 0.004, P < 0.001, respectively). In addition, the clonidine group had lower mean arterial pressures, heart rates and higher sedation scores compared to the controls (P < 0.05 for all).
Conclusion: Use of clonidine (150 µg) as adjuvant for lidocaine in axillary blocks for arteriovenous fistula construction in chronic renal failure patients prolongs blockade, decreases both heart rates and blood pressures and provides sedative effects.

Anterior sciatic nerve block new landmarks and clinical experience
M. Wiegel, A. Reske, R. Hennebach, F. Schmidt, T. Elias, H. Gupta and D. Olthoff
Acta Anaesthesiologica Scandinavica 2005; 49: 552 - 7

Background: Anterior sciatic nerve blocks can be complicated by several problems. Pain can be caused by bony contacts and, in obese patients, identification of the landmarks is frequently difficult.
Methods: In a first step, 100 normal anterior-posterior pelvic X-rays were analyzed. The landmarks of the classical anterior approach were drawn on these X-rays and assessed for their sufficiency. Then, in a prospective case study, 200 consecutive patients undergoing total knee replacement were investigated. These patients received femoral and sciatic nerve catheters for postoperative pain management. Using modified anatomical landmarks, sciatic nerve catheters were inserted 5 cm distal from the insertion site of the femoral nerve block perpendicularly in the midline of the lower extremity. This midline connected the insertion site of the femoral nerve catheter to the midpoint between the medial and lateral epicondyle. Correct catheter positioning was verified by magnetic resonance imaging (MRI) in six patients.
Results: Evaluation of pelvic X-rays showed that puncture following the classical landmarks pointed in 51% at the lesser trochanter, in 5% medial to the lesser trochanter and in 42% directly at the femur. In the latter patients, location of the sciatic nerve would have been difficult or even impossible. Using our modified anterior approach, the sciatic nerve could be blocked in 196 patients (98%). In nine patients (4.5%) blockade of the posterior femoral cutaneous nerve failed. Vascular puncture happened in 10 (5%) and bony contact in 35 patients (17.5%). Median puncturing depth was 9.5 (7.5 14) cm. Correct sciatic nerve catheter positioning was verified in all patients who underwent MRI.
Conclusion: Our landmarks for locating the sciatic nerve help to avoid bony contacts and thereby reduce pain during puncture. Our method reliably enabled catheter placement.

BRITISH JOURNAL OF ANAESTHESIA - TOP

Combined ilioinguinal blockade and local infiltration anaesthesia for groin hernia repair—a double-blind randomized study
F. H. Andersen, K. Nielsen and H. Kehlet
British Journal of Anaesthesia 2005;94(4):520-523

Background. Local infiltration anaesthesia for inguinal hernia repair is cost-effective, but fear of intra-operative pain may hinder its widespread use. It is unknown whether a combined ilioinguinal blockade and local infiltration anaesthesia improves intra-operative analgesia.
Methods. We performed a double-blind randomized study in 160 patients undergoing inguinal hernia mesh repair under local infiltration anaesthesia with or without additional ilioinguinal blockade. Intra-operative pain and pain at 24 and 48 h postoperatively and analgesic requirements (acetaminophen, ibuprofen, and tramadol) were assessed.
Results. Median intra-operative pain scores were reduced (P=0.02) from 13 to 9 with additional ilioinguinal blockade, with no differences in requirement for sedation. There were significantly (P<0.05) more patients with intra-operative visual analogue pain scale 30 in the placebo group vs the ilioinguinal blockade group. Postoperative pain scores and analgesic requirements were similar.
Conclusion. Combined ilioinguinal blockade and local infiltration anaesthesia is recommended for groin hernia repair to reduce intra-operative pain.

CANADIAN JOURNAL OF ANESTHESIA - TOP

The Stealth Station^TM Image Guidance System may interfere with pulse oximetry
Johannes H. van Oostrom, PhD, Michael E. Mahla, MD and Dietrich Gravenstein, MD
Can J Anesth 52:379-382 (2005)

Purpose: Interference on pulse oximetry can come from many sources. We found an additional source of interference from the Stealth Station^TM. This article gives an overview of sources of pulse oximeter interference so that clinicians can better prevent them.
Technical features: This article discusses the infrared disturbances caused by the Stealth Station^TM. The Stealth Station^TM is a frameless stereotactic positioning system that utilizes a three dimensional location system to measure the position of the patient and the surgical tools, and to relate those positions to previously recorded imaging. To understand the disturbance caused by the Stealth Station^TM, we discuss its operation and that of pulse oximeter monitors. Pulse oximeter interference can come from volume artifacts, electrical and light noise, and can be caused by issues related to the patient. Because the passive Stealth Station^TM contains a strong infrared light source, interference caused by light is a likely reason for the interference we noted. Pulse oximeters rely on the time-variant light signal modulated by arterial volume variations in the finger. Although relatively immune to static light sources, pulse oximeters are extremely sensitive to time-varying light sources. The light emitted by the passive Stealth Station^TM is time-varying at 4 Hz and this is causing the pulse oximeter to provide invalid results. Shielding can generally be used to stop the light from the Stealth Station^TM from being picked up by the pulse oximeter sensor.
Conclusion: Infrared light interference can be very common, but is easily dealt with if one is aware of it.

Noncardiac surgery in patients with coronary artery stent: what should the anesthesiologist know? (EDITORIAL)
Jean-Yves Dupuis and Marino Labinaz
Can J Anesth 2005 52: 356-361

No abstract available.

PUB MED - TOP

Rapid, needle-free delivery of lidocaine for reducing the pain of venipuncture among pediatric subjects.
Migdal M, Chudzynska-Pomianowska E, Vause E, Henry E, Lazar J.
Pediatrics. 2005 Apr;115(4):e393-8.

OBJECTIVES: The purpose of this study was to determine the optimal configuration of an investigational, single-use, needle-free, drug system (ALGRX 3268) that delivers powdered lidocaine into the epidermis for the rapid production of local anesthesia among pediatric subjects undergoing venipuncture.
METHODS: Children 3 to 18 years of age were randomly allocated to receive 1 of 3 treatments, ie, (1) placebo, (2) a system configured to deliver 0.25 mg of lidocaine, or (3) a system configured to deliver 0.5 mg of lidocaine, at the antecubital fossa 2 to 3 minutes before venipuncture. Three age groups were included, ie, 3 to 7 years, 8 to 12 years, and 13 to 18 years. Two sets of pain rating scales were used, the Faces Pain Scale-Revised for the youngest age stratum and a visual analog scale for the oldest age stratum. Children in the middle age stratum used both scales.
RESULTS: One-hundred forty-four subjects completed the study. For all ages combined, there was a statistically significant and clinically meaningful reduction in pain scores for subjects who received 0.5 mg of lidocaine, compared with placebo. The reduction in pain after 0.25 mg of lidocaine did not achieve statistical significance.
CONCLUSIONS: Both active configurations were safe and well tolerated by pediatric subjects undergoing venipuncture at the antecubital fossa. ALGRX 3268 at 0.5 mg, administered 2 to 3 minutes before venipuncture, produced significantly lower pain scores, compared with placebo.

A prospective study comparing the analgesic efficacy of levobupivacaine, ropivacaine and bupivacaine in pediatric patients undergoing caudal blockade.
Breschan C, Jost R, Krumpholz R, Schaumberger F, Stettner H, Marhofer P, Likar R.
Paediatr Anaesth. 2005 Apr;15(4):301-6.

BACKGROUND: The aim of our study was to compare postoperative analgesic efficacy, analgesic duration and motor blockade of levobupivacaine, ropivacaine and bupivacaine administered caudally in equal concentrations to children undergoing elective minor surgery.
METHODS: In the study, 182 children, aged 1-7 years, undergoing either inguinal hernia repair or orchidopexy, were randomly allocated to one of the three groups. They received via a caudal extradural either 1 ml x kg^-1 levobupivacaine 0.2% (Group L) or 1 ml x kg^-1 ropivacaine 0.2% (Group R) or 1 ml x kg^-1 bupivacaine 0.2% (Group B).
RESULTS: No statistically significant difference was noted in age, weight, duration of the operation or level of the caudal block between the groups. The onset of analgesia was significantly later after levobupivacaine. Postoperative pain scoring evaluated with Children's and Infant's Postoperative Pain Scale observational scale showed no statistical difference between groups. Median postoperative analgesia was 5.75 h (SEMed: +/- 0.65) in Group L, 5.7 h (SEMed: +/- 0.8) in Group R and 5.35 h (SEMed: +/- 1.3) in Group B the difference being statistically nonsignificant.
CONCLUSIONS: The degree of motor block was significantly less after ropivacaine and levobupivacaine during the first 2 h postoperatively.

A case of supercarbia following pneumoperitoneum in an infant.
Lew YS, Thambi Dorai CR, Phyu PT.
Paediatr Anaesth. 2005 Apr;15(4):346-9.

A 4-month-old healthy male infant underwent left herniotomy under general anesthesia with caudal block. Carbon dioxide (CO₂) pneumoperitoneum was created through the left hernial sac for inspection of the right processus vaginalis. Episodes of desaturation associated with significant reduction in chest compliance were noted intraoperatively. This was overcome by increasing the inspired oxygen concentration (FiO₂). The infant failed to regain consciousness and spontaneous respiration at the end of surgery. The chest compliance deteriorated further and clinically a CO₂ pneumothorax (capnothorax) was suspected. The endtidal carbon dioxide (PECO₂) was initially low in the immediate postoperative period. Subsequent to the readministration of sevoflurane and manual ventilation with a Jackson Rees circuit, a sudden surge in PECO₂ with improvement of chest compliance was observed. At that time arterial blood gas (ABG) analysis revealed a PCO2 of 17.5 kPa (134 mmHg) and pH of 6.9. The causes of severe hypercarbia and the physiological changes observed in this infant are discussed.

Anesthesia in the obese patient: Pharmacokinetic considerations.
Casati A, Putzu M
J Clin Anesth. 2005 Mar;17(2):134-45.

The prevalence of obesity has increased 15% up to 20% and represents an important challenge for the anesthesiologist in drug-dosing management. The aim of this work is to provide an overview on physiological changes and pharmacokinetic implications of obesity for the anesthesiologist. Obesity increases both fat and lean masses; however, the percentage of fat tissue increases more than does the lean mass, affecting the apparent volume of distribution of anesthetic drugs according to their lipid solubility. Benzodiazepine loading doses should be adjusted on actual weight, and maintenance doses should be adjusted on ideal body weight. Thiopental sodium and propofol dosages are calculated on total body weight (TBW). The loading dose of lipophilic opioids is based on TBW, whereas maintenance dosages should be cautiously reduced because of the higher sensitivity of the obese patient to their depressant effects. Pharmacokinetic parameters of muscle relaxants are minimally affected by obesity, and their dosage is based on ideal rather than TBW. Inhalation anesthetics with very low lipid solubility, such as sevoflurane and desflurane, allow for quick modification of the anesthetic plan during surgery and rapid emergence at the end of surgery, hence representing very flexible anesthetic drugs for use in this patient population. Drug dosing is generally based on the volume of distribution for the loading dose and on the clearance for maintenance. In the obese patient, the volume of distribution is increased if the drug is distributed both in lean and fat tissues whereas the anesthetic drug clearance is usually normal or increased.

Target-controlled infusion of remifentanil or fentanyl during extra-corporeal shock-wave lithotripsy.
Cortinez LI, Munoz HR, De la Fuente R, Acuna D, Dagnino JA.
Eur J Anaesthesiol. 2005 Jan;22(1):56-61.

BACKGROUND AND OBJECTIVE: Target-controlled infusions (TCIs) of remifentanil and fentanyl in conscious sedation regimes for extra-corporeal shock-wave lithotripsy have not been reported. We estimated the effect site concentrations of remifentanil and fentanyl needed to obtain adequate analgesia in 50% of patients (EC50) and compared both drugs in terms of intra- and post-procedure complications.
METHODS: Forty-four adult patients were randomly distributed into two groups: Group R received remifentanil and Group F received fentanyl TCI with initial effect site concentrations of 1.5 and 2 ng mL^-1, respectively. Pain was assessed using a 10-point verbal analogue scale and <3 was considered adequate analgesia. Increments or decrements of 0.5 ng mL^-1 were then introduced for subsequent patients according to Dixon's up and down method. During the rest of the procedure, TCI was adjusted to maintain verbal analogue scale <3.
RESULTS: Remifentanil and fentanyl EC50 were 2.8 ng mL^-1 (95% confidence interval (CI): 1.8-3.7 ng mL^-1) and 2.9 ng mL^-1 (95% CI: 1.7-4.1 ng mL^-1), respectively (n.s.). At EC50, the probability of having a respiratory rate <10 was 4% (95% CI: 0-57%) for remifentanil and 56% (95% CI: 13-92%) for fentanyl. Hypoxaemia, vomiting and sedation were more frequent in Group F during and after the procedure (P < 0.05).
CONCLUSIONS: A similar EC50 but more respiratory depression, sedation and PONV were found with fentanyl TCI than with remifentanil TCI.

Comparison of ephedrine and ketamine in prevention of injection pain and hypotension due to propofol induction.
Ozkocak I, Altunkaya H, Ozer Y, Ayoglu H, Demirel CB, Cicek E.
Eur J Anaesthesiol. 2005 Jan;22(1):44-8

BACKGROUND AND OBJECTIVE: This prospective, double-blind, randomized, placebo-controlled study compares the effects of ephedrine and ketamine on injection pain, and hypotension from propofol.
METHODS: After obtaining the approval of the Ethics Committee, 75 patients (ASA I-II) scheduled for elective operations with general anaesthesia were divided into three groups. Saline 2 mL (Group S, n = 25), ketamine 0.5 mg kg^-1 (Group K, n = 25) or ephedrine 70 microg kg^-1 (Group E, n = 25) were administered over 5 s after tourniquet application. After releasing the tourniquet, propofol 2 mg kg^-1 was injected in 30 s. Pain was evaluated on a numerical scale (0-10) where 0 represented no pain and 10 the most severe pain possible. Systolic, diastolic blood pressures and heart rates were recorded preoperatively, 1 min after propofol injection, before intubation and 1, 2 and 3 min after intubation in all patients.
RESULTS: The incidences of pain in Groups S, E and K were similar (84%, 80% and 72%, respectively). The mean pain score in Group K (2.1, SD 3.1) was significantly lower than those of Groups S and E (4.9, SD 2.6 and 4.6, SD, 3.3, respectively) (P < 0.05). The systolic and diastolic blood pressure values in Group K (120 +/- 27 mmHg) and Group E (123 +/- 21 mmHg) before intubation were significantly higher than that of Group S (104 +/- 25 mmHg) (P < 0.05). There was no significant difference between the mean heart rate values of the groups.
CONCLUSIONS: Low dose ketamine or ephedrine pretreatment may prevent hypotension due to propofol induction. Despite the reduction in injection pain intensity after ketamine, the study drugs were found to be ineffective in lowering the injection pain incidence.

Stress reduction and analgesia in patients exposed to calming music postoperatively: a randomized controlled trial.
Nilsson U, Unosson M, Rawal N.
Eur J Anaesthesiol. 2005 Feb;22(2):96-102.

BACKGROUND AND OBJECTIVES: This randomized controlled trial was designed to evaluate, first, whether intra- or postoperative music therapy could influence stress and immune response during and after general anaesthesia and second, if there was a different response between patients exposed to music intra- or postoperatively.
METHOD: Seventy-five patients undergoing open hernia repair as day care surgery were randomly allocated to three groups: intraoperative music, postoperative music and silence (control group). Anaesthesia and postoperative analgesia were standardized and the same surgeon performed all the operations. Stress response was assessed during and after surgery by determining the plasma cortisol and blood glucose levels. Immune function was evaluated by studying immunoglobulin A (IgA) levels. Patients' postoperative pain, anxiety, blood pressure (BP), heart rate (HR) and oxygen saturation were also studied as stress markers.
RESULTS: There was a significantly greater decrease in the level of cortisol in the postoperative music group vs. the control group (206 and 72 mmol L^-1 decreases, respectively) after 2 h in the post anaesthesia care unit. The postoperative music group had less anxiety and pain and required less morphine after 1 h compared with the control group. In the postoperative music group the total requirement of morphine was significantly lower than in the control group. The intraoperative music group reported less pain after 1 h in the post anaesthesia care unit. There was no difference in IgA, blood glucose, BP, HR and oxygen saturation between the groups.
CONCLUSION: This study suggests that intraoperative music may decrease postoperative pain, and that postoperative music therapy may reduce anxiety, pain and morphine consumption.

Pharmacokinetics and pharmacodynamics of rocuronium in patients with and without renal failure.
Robertson EN, Driessen JJ, Booij LH.
Eur J Anaesthesiol. 2005 Jan;22(1):4-10.

BACKGROUND AND OBJECTIVE: This study clarifies the relationship between the neuromuscular blocking effects of rocuronium 0.6 mg kg^-1 and its pharmacokinetics in patients with renal failure.
METHODS: Seventeen healthy patients and 17 patients with renal failure were studied under propofol anaesthesia in this prospective open label study. Rocuronium 0.6 mg kg^-1 was given after induction of anaesthesia. The train-of-four mechano-myographic response of the thumb to supramaximal stimulation of the ulnar nerve at 2 Hz every 12 s was measured. Venous blood samples (4 mL) were obtained at 0, 2, 4, 7, 10, 15, 20, 30, 60, 120, 180, 240 and 360 min after relaxant administration. Samples were centrifuged, separated and stored at -20 degrees C until plasma levels of rocuronium and its metabolites were measured. Two- and three-exponential equations were used to describe the pharmacokinetic data in each group and these were compared to each other using the Wilcoxon signed rank sum test as was the pharmacodynamic data. P < 0.05 was significant.
RESULTS: Onset of block was similar in both groups. Clinical duration and the time to recovery of the train-of-four to 70% were prolonged in the renal failure group compared to control; 49 vs. 32 min (P < 0.004, 95% confidential, interval 17, difference 5-28) and 88 vs. 55 min (P < 0.001, 95% confidential interval 33, difference 17-50), respectively. Clearance of rocuronium was reduced by 39% in the renal failure patients compared to control, with an 84% increase in the mean residence time. The volume of distribution was unaffected by renal failure.
CONCLUSIONS: The duration of action of a bolus dose of 0.6 mg kg^-1 rocuronium is increased significantly in patients with end-stage renal failure compared to healthy controls. This increase may be due to a decreased clearance of rocuronium, the disease process causing the renal failure and/or the medication which patients with renal failure need in their treatment.

Impact of patient age on propofol consumption during propofol-remifentanil anaesthesia.
Kreuer S, Schreiber JU, Bruhn J, Wilhelm W.
Eur J Anaesthesiol. 2005 Feb;22(2):123-8.

BACKGROUND: This study was designed to investigate the impact of patient age on propofol consumption and recovery time using a propofol-remifentanil anaesthetic standardized with Narcotrend EEG monitoring. The Narcotrend is a monitor for measuring the depth of anaesthesia based upon a six-letter classification from A (awake) to F (increasing burst suppression) including 14 substages.
METHODS: In 200 patients scheduled for minor orthopaedic surgery Narcotrend EEG electrodes were positioned on the patient's forehead as recommended by the manufacturer. Anaesthesia was induced with remifentanil 0.4 microg kg^-1 min^-1 and 2 mg kg^-1 propofol. Immediately after intubation remifentanil was reduced to a constant rate of 0.2 microg kg^-1 min^-1 whereas a propofol infusion was now started at 3 mg kg^-1 h^-1 and then adjusted accordingly to achieve a target Narcotrend stages of D(0-2) indicating general anaesthesia. At the end of surgery the propofol and remifentanil infusions were stopped without tapering, the time to unstimulated opening of eyes was determined, and the propofol consumption (given as mg kg^-1 h^-1 ) was calculated from the total amount of infused propofol but without the induction bolus, from the actual body weight and the duration of propofol infusion. Furthermore, a linear regression analysis was applied for propofol consumption vs. age.
RESULTS: The ages of the patients studied ranged from 16 to 83 yr old and patients were classified as ASA I-III. Propofol consumption significantly decreased with the patients' age: 30 yr of age or below the propofol consumption was calculated as 5.9 +/- 1.7 mg kg^-1 h^-1 , for 31-50 yr as 5.4 +/- 1.8 mg kg^-1 h^-1 , for 51-70 yr as 4.5 +/- 1.7 mg kg^-1 h^-1 and above 70 yr as 3.5 +/- 1.4 mg kg^-1 h^-1 . Linear regression analysis revealed propofol (mg kg^-1 h^-1) = 9.136 - (0.0597 x age (yr)); R = 0.53. Concomitantly, the recovery time to opening of eyes increased with the patients' age: < or = 30 yr, 7.4 +/- 3.7 min; 31-50 yr, 9.5 +/- 4.0 min; 51-70 yr, 9.8 +/- 4.1 min; and > or = 71 yr, 14.9 +/- 12.1 min.
CONCLUSIONS: We conclude that with Narcotrend guidance, mean propofol consumption and recovery times are age dependent. However, as a result of large inter-individual variability, age per se does not allow a prediction of individual propofol need or recovery time.

Remifentanil for analgesia during retrobulbar nerve block placement.
Leidinger W, Schwinn P, Hofmann HM, Meierhofer JN.
Eur J Anaesthesiol. 2005 Jan;22(1):40-3.

BACKGROUND AND OBJECTIVES: Patients undergoing eye surgery under regional anaesthesia often require concomitant medication for analgesia and comfort. Remifentanil, with its ultra-short acting-profile, may be useful to reduce pain during retrobulbar nerve block for cataract surgery.
METHODS: We performed a prospective, randomized, double-blind study to compare the efficacy of remifentanil for analgesia during retrobulbar nerve block placement. Ninety patients undergoing cataract surgery were randomly divided to receive either remifentanil 0.3 microg kg^-1 (n = 45) or an equivalent volume of saline (n = 45). The injection was administered within 30 s in both groups. Patients rated their amount of pain on a 10 cm visual analogue scale. Respiratory frequency, oxygen saturation, cardiac rhythm and postoperative nausea and vomiting (PONV) were recorded.
RESULTS: The mean visual analogue score in the Remifentanil group was 2.56; it was 5.51 in the Saline group (P = 0.001, U-test). Three patients developed bradycardia and three had PONV in the Remifentanil group. Two patients developed tachycardia and one had PONV in the Saline group. No patient developed respiratory depression.
CONCLUSION: In patients undergoing retrobulbar block placement for eye surgery, 0.3 microg kg^-1 remifentanil over 30 s significantly reduced their reported pain. In addition, remifentanil did not increase the risk of untoward side-effects.

Pre-emptive effects of ibuprofen syrup and lidocaine infiltration on post-operative analgesia in children undergoing adenotonsillectomy.
Kedek A, Derbent A, Uyar M, Bilgen C, Uyar M, Kirazli T, Certug A.
J Int Med Res. 2005 Mar-Apr;33(2):188-95.

We aimed to compare the effects of lidocaine and adrenaline with ibuprofen syrup (administered before adenotonsillectomy) on post-operative analgesia and initiation of oral feeding. One group of 20 children received 100 g/5 ml ibuprofen suspension (10 mg/kg) 1 h before anaesthesia; bleeding control was provided by pre-incisional administration of 1:200,000 adrenaline solution (10 ml). The same amount of 0.5% lidocaine solution plus 1:200,000 adrenaline was applied pre-incisionally in a similar manner in a second group of 20 children. No significant differences were observed between the two groups in terms of the duration of operation and anaesthesia, post-operative pain scores, paracetamol requirements, times to initiation of liquid and solid food intake, or adverse side-effects. We conclude that ibuprofen syrup applied pre-incisionally and local infiltration with lidocaine are equally effective for post-operative analgesia.

Comparison of a combination of midazolam and diazepam and midazolam alone as oral premedication on preanesthetic and emergence condition in children.
Arai YC, Fukunaga K, Hirota S.
Acta Anaesthesiol Scand. 2005 May;49(5):698-701.

Background: Preanesthetic anxiety and emergence agitation are major challenges for anesthesiologists in pediatric anesthesia. Thus, midazolam has been used as premedication for children. However, midazolam alone is not effective for emergence agitation. The present study tested the effect of a combination of midazolam and diazepam on the preanesthetic condition and emergence behavior in children.
Methods: Forty-two children were allocated to one of three groups: the NoPre group received no premedication; the Mi group received midazolam 0.5 mg kg^-1 orally; and the Mi + Di group received midazolam 0.25 mg kg^-1 and diazepam 0.25 mg kg^-1 orally. When anesthesia was induced with 7% sevoflurane in 100% oxygen, qualities of mask induction and sedation were rated. Anesthesia was maintained with sevoflurane (3-5%) in 100% oxygen. During emergence from anesthesia, the score of the child's emergence behavior was rated.
Results: Children in the Mi and Mi + Di groups were more sedated than those in the NoPre group. A combination of midazolam and diazepam provided a better quality of mask induction, when compared with no premedication. Also, the children in the Mi + Di group were less agitated than those in the other groups during the emergence.
Conclusion: Children in the Mi + Di group were significantly more sedated at induction of anesthesia and less agitated during emergence from anesthesia.

Laparoscopic adjustable gastric banding: early experience in 400 consecutive patients in the USA.
Watkins BM, Montgomery KF, Ahroni JH.
Obes Surg. 2005 Jan;15(1):82-7

BACKGROUND: Early experience with 400 consecutive patients who underwent laparoscopic adjustable gastric banding (LAGB) is reported.
METHODS: From Nov 2002 to Aug 2004, prospective data were collected on 400 consecutive LAGB patients and evaluated retrospectively.
RESULTS: There were 354 (88.5%) females and 46 males (11.5%), with mean age 43.6 years and mean BMI 46.2 kg/m². For outpatients (freestanding ambulatory surgery center), mean OR time was 55.4 min in 208 patients (52%), compared to mean inpatient OR time of 70.5 min in 192 patients. Inpatients had a higher BMI (48.2 +/- 9.3 SD) than outpatients (43.9 +/- 5.7 SD) (P<0.0001). Complications occurred in 35 patients (8.8%). These consisted of 9 slipped bands (2.3%) that were surgically repositioned, 6 port problems (1.5%) that were successfully repaired, 17 patients with temporary stoma occlusion (4.3%) that spontaneously resolved, and 2 bowel perforations (0.5%) that required surgical repair and band removal. One patient died of pneumonia 2 weeks after an uneventful procedure. Average 1-year percent excess weight loss (%EWL) in 138 patients was 48.2%. Patients who had < or =50 kg initial excess weight (n=37, 27%) had a significantly higher %EWL (55.2%) at 1 year than patients who had >50 kg initial excess weight (P=0.0011).
CONCLUSIONS: LAGB has been safe and effective thus far for the surgical treatment of morbid obesity, and can be performed as an outpatient in select patients.

Hemodynamic effects of perioperative stressor events during rhinoplasty
Demirtas, Y., S. Ayhan, et al.
Plast Reconstr Surg 2005; 115(2): 620-6.

The hemodynamic effects of perioperative stressors, including preoperative patient anxiety, intraoperative local anesthetic/adrenaline infiltrations, and some painful interventions, have not been fully elucidated in plastic surgery procedures. The present study was designed to determine the hemodynamic effects of perioperative stressor events in American Society of Anesthesiologists class I patients undergoing rhinoplasty procedures under general anesthesia. The study included 50 healthy patients, 18 to 51 years of age (mean age, 27 +/- 7 years), who underwent a rhinoplasty procedure in the authors' department. All patients were connected to a digital ambulatory Holter recorder for 24 hours starting on the day before the operation and continuing throughout the procedure. All of the patients received 10 ml of 2% lidocaine with 1:80,000 adrenaline 15 minutes after intubation. Observations consisted of heart rate, noninvasive blood pressure, and power spectral heart rate variability analyses, the latter of which is indicative of the sympathovagal balance of the patients. The majority of patients developed a persistent, moderate sinus tachycardia before the induction of anesthesia. After the infiltration of lidocaine/adrenaline, a mild to moderate and short-lasting tachycardia was detected. A similar increase in pulse rate was also noticed during lateral osteotomies. No significant blood pressure changes attributable to perioperative stressors (with the exclusion of general anesthesia induction, intubation, and extubation) were observed. Sympathetic activity was found to be responsible from marked tachycardia before the induction, which was attributable to preoperative anxiety. The authors' study has demonstrated that there are three hemodynamically unstable periods causing tachycardia for rhinoplasty patients that directly concern the plastic surgeon: immediate preoperative anxiety, local anesthetic/adrenaline injection, and lateral osteotomies. The authors conclude that these patients would benefit from routine use of premedications and that a lidocaine/adrenaline combination is a safe adjunct to general anesthesia in young rhinoplasty patients. In addition, a deeper anesthesia during local infiltration and osteotomies would be appropriate.

Ventilation with the laryngeal tube in pediatric patients undergoing elective ambulatory surgery
Genzwuerker, H. V., E. Hohl, et al.
Paediatr Anaesth 2005; 15(5): 385-90.

Summary Background: The laryngeal tube is a new supraglottic alternative for securing the airway. Few data on the use of this airway device in pediatric patients are so far available. Experiences of the study are reported.
Methods: Use of the laryngeal tube for ventilation during intermittent positive-pressure ventilation was studied in an open, noncomparative observational study in 80 pediatric patients (age: 2-12 years) undergoing elective ambulatory surgery. Insertion success, time to achieve a patent airway, and occurrence of adverse events were documented.
Results: Mean (sd) patient age was 5.8 (2.3) years. The laryngeal tube was placed at the first attempt in 90% of patients, a second attempt was necessary in 6%. Ventilation was not possible after two attempts in three patients. Mean (sd) tidal volume was 10.1 (2.0) ml.kg^-1 with a mean (sd) peak airway pressure of 15.6 (2.1) cmH₂O. Chin lift was applied to improve ventilation in 15 patients (18.8%). Laryngospasm occurred in one patient, but ventilation was possible after adapting depth of anesthesia. Mean (sd) time for airway maintenance was 11.2 (3.7) s. No gastric insufflation of air occurred, no traces of blood could be detected after removal of the device. One patient complained of mild problems (swallowing, VAS 1). Mean (sd) anesthesia time was 44 (9) min.
Conclusions: In the age group studied, the laryngeal tube provides a rapid, patent airway in the majority of patients with a low complication rate.

One-stop hysteroscopy clinic for postmenopausal bleeding.
Lotfallah, H., K. Farag, et al.
J Reprod Med 2005; 50(2): 101-7.

OBJECTIVE: To evaluate the role and feasibility of the "1-stop" clinic for management of postmenopausal bleeding, based on the use of transvaginal ultrasound and hysteroscopic examination under local anesthesia.
STUDY DESIGN: A retrospective analysis of 308 patients referred to the clinic between October 2000 and May 2002 was carried out. Endometrial thickness of > 4 mm, as measured by transvaginal scan, was considered the cutoff limit for further investigation by hysteroscopy.
RESULTS: Three hundred eight patients were seen in the 1-stop clinic. One hundred ten (35.7%) had endometrial thickness < or = 4 mm with no other associated abnormal findings and were discharged without proceeding to hysteroscopy. In 8 patients the scan was not conclusive, and they were offered hysteroscopy. Another 4 had a fluid-filled uterine cavity on sonography and were offered dilatation and curettage under general anesthesia. Eight patients opted to have the hysteroscopy done under general anesthesia, and in 12, hysteroscopy failed under local anesthesia. Outpatient hysteroscopy was performed in 174 cases; 86 (49.4%) had normalfindings and were discharged. Endometrial polyps were found in 55 (31.6%) patients; in 42 the polyp was successfully removed at the same setting. Twenty patients (11.5%) had submucous fibroids and were discharged. A suspicious lesion was found in 13 (7.5%) patients; histologic examination confirmed endometrial carcinoma. A total of 216 of 308 (70%) patients were totally managed and discharged at the first visit with no further follow-up, and hospital admission was avoided in 258 (83.7%) of cases.
CONCLUSION: The 1-stop clinic is effective in reducing the number of hospital visits per patient as well as hospital admissions and the waiting list.

Popliteal fossa sciatic nerve block for ambulatory hallux valgus surgery: comparison of lateral and posterior approaches
Suarez Ruiz, P., S. Lopez Alvarez, et al.
Rev Esp Anestesiol Reanim 2005; 52(1): 4-8.

Full paper published in Spanish.

OBJECTIVE: The aim of this study was to assess the efficacy, effectiveness, technical difficulty, and clinical usefulness of the popliteal sciatic peripheral nerve block for unilateral hallus valgux surgery and to compare the posterior and lateral approaches. We also aimed to investigate patient comfort during the procedure.
MATERIALS AND METHODS: This prospective, randomized trial enrolled 60 patients
scheduled for unilateral hallux valgus surgery. The patients were randomly assigned to groups of 30 patients to receive a nerve block by either a posterior or lateral approach. A nerve stimulator was used to locate the response of the two branches forming the sciatic nerve--the posterior tibial nerve and the common peroneal nerve. Then, 20 mL of 0.5% ropivacaine was injected for each nerve. Variables analyzed were efficacy, complications, quality and duration of postoperative analgesia, degree of comfort while the technique was being performed, and level of satisfaction.
RESULTS: The level of comfort was good for 19 patients (70%) in the posterior approach group and for 29 (97%) in the lateral approach group (P<0.05). Level of satisfaction was good or very good for 93% and 96% of the patients in the posterior and lateral approach groups, respectively. Block efficacy was excellent for 48 patients (80%), good for 9 (15%), and poor for 3 (5%), with no significant differences between the groups.
CONCLUSION: Both the posterior and lateral approaches provide easy access to the sciatic nerve for performing a block. The rate of success is high and postoperative analgesia is good, with no noteworthy complications. However, the lateral approach is more comfortable for the patient.

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