Michael H. Nathanson

Prevention of pain on injection of propofol: a comparison of lidocaine with alfentanil.

We undertook a randomized, placebo-controlled, double-blind study to compare the use of alfentanil 1 mg and lidocaine 40 mg for the reduction of pain during injection of propofol. Eighty-nine patients were randomly allocated to one of three groups: Group L, lidocaine 40 mg added to 180 mg propofol; Group A, alfentanil 1 mg 30 s prior to propofol; or Group P, placebo (normal saline). The incidence of pain in the placebo group was 67%. Both treatment groups had a significantly lower incidence of pain than the placebo group (P < 0.002). There was no significant difference in the incidence of pain between the groups receiving lidocaine or alfentanil (13% and 24%, respectively). There was no significant difference in the induction dose of propofol between the groups. Fifty-two percent of patients who experienced pain at induction had recall of that pain in the recovery room. Alfentanil 1 mg and lidocaine 40 mg are both effective in reducing pain during injection of propofol. (Anesth Analg 1996;82:469-71)

Preventing pain during injection of propofol: the optimal dose of lidocaine

STUDY OBJECTIVE To define the optimal dose of lidocaine to be added to propofol to reduce the incidence of pain during its injection. DESIGN Double-blind, randomized, placebo-controlled study. SETTING Medical center operating rooms. PATIENTS 135 ASA I and II female patients undergoing minor outpatient surgery. INTERVENTIONS Patients were randomly allocated to one of five groups: Group A (control), no lidocaine: Group B, lidocaine 10 mg: Group C, lidocaine 20 mg; Group D, lidocaine 30 mg; Group F, lidocaine 40 mg. For each patient, pain during injection of the propofol solution was graded as none, mild, moderate, or severe. MEASUREMENTS AND MAIN RESULTS The incidence of pain in the control group was 85%. All treatment groups receiving lidocaine had a significantly lower incidence of pain compared with the control group (P < 0.001). The lidocaine 30 mg and 40 mg groups both had a 7% incidence of pain, which was significantly less than a 33% incidence in the lidocaine 10 mg group (P < 0.05). CONCLUSIONS Within this dose range and in this patient population, 30 mg of lidocaine is optimal for reducing the pain during injection of propofol.

Cerebral hemodynamic response to the introduction of desflurane: A comparison with sevoflurane.

Rapid increases in the inspired concentration of desflurane cause transient increases in heart rate and blood pressure. Desflurane also impairs cerebral autoregulation at clinical concentrations. Sevoflurane does not share these hemodynamic side effects. We compared the cerebral and systemic hemodynamic responses to the introduction of desflurane or sevoflurane after the induction of anesthesia with propofol. Twenty healthy adult patients scheduled for nonneurological surgery were recruited. After the induction of anesthesia with propofol, either desflurane or sevoflurane (n = 10 per group) was introduced at 7.2% or 2.2%, respectively, and increased to 10.8% or 3.3%, respectively, 2 min later. Middle cerebral artery blood flow velocity was measured continuously by using a 2-MHz transcranial Doppler ultrasound probe. Heart rate and blood pressure were recorded at 1-min intervals during the 12-min study period. Those patients receiving desflurane had significantly greater middle cerebral artery blood flow velocities, heart rates, and blood pressures than those receiving sevoflurane (P < 0.01). Implications The introduction of desflurane after the induction of anesthesia leads to significant disturbances in cerebral and systemic hemodynamics suggesting loss of cerebral autoregulation and cerebral hyperemia. This may have implications for patients undergoing anesthesia for intracranial surgery.

The role of sevoflurane in outpatient anesthesia

Sevoflurane appears to have several properties that make it an attractive alternative to the currently available anesthetics for outpatient anesthesia. The relative low solubility of sevoflurane, as well as an impressive lack of airway irritation, makes it a very useful anesthetic for inhalation induction of anesthesia. This feature is likely to make sevoflurane a population choice for pediatric outpatient anesthesia. For adult outpatients, the relatively low solubility of sevoflurane permits rapid alterations in alveolar concentration during the maintenance period (even when administered at relatively low flow rates of 2-3 L/min), thereby improving control of the depth of anesthesia. Low solubility should also allow for a more predictable emergence from anesthesia (versus isoflurane), thereby facilitating patient turnover in a busy ambulatory surgery center. The commercial development of sevoflurane has been slow because of concerns regarding the potential toxicity of its metabolites and breakdown products (24). However, the large body of clinical experience from Japan and the worldwide Phase II and III clinical development programs suggests that these concerns may be unfounded. The short duration of exposure in the outpatient setting should further decrease the risk of nephrotoxicity. The relatively low solubility of sevoflurane will facilitate its use with total gas flow rates of 2-3 L/min. In the final analysis, clinicians will have to balance the cost of sevoflurane (versus halothane, enflurane, isoflurane, and desflurane) against its potential advantages in the ambulatory surgery population. Although the search for anesthetics that are more ideally suited for use in the outpatient setting will continue, sevoflurane clearly represents a step in the right direction (3).

Sevoflurane for interventional neuroradiology procedures is associated with more rapid early recovery than propofol

PurposeSevoflurane and propofol are both suitable for neuroanesthesia but have not previously been compared as maintenance agents for long duration (one to five hours) procedures.MethodsUsing a multicentre international study protocol, 103 patients were randomized to receive either sevoflurane or propofol for maintenance of anesthesia during interventional neuroradiology procedures. After a standardized induction of anesthesia with propofol, 53 patients received sevoflurane 1 to 3% with 60% nitrous oxide (N2O) in oxygen (O2), and 50 patients received propofol 4 to 10 mg·kg−1·hr−1 with 60% N2O in O2. Maintenance agents were titrated against systemic arterial blood pressure (baseline mean arterial pressure ± 20%). Recovery times, changes in sedation, pain, nausea and vomiting and psychomotor function during recovery and use of rescue medication were recorded.ResultsThe group receiving sevoflurane had a more rapid recovery to spontaneous ventilation, extubation, eye opening and orientation compared to the group receiving propofol (3 vs 4 min,P = 0.01; 5 vs 6min,P = 0.015; 7vs 10 min,P < 0.001; 13vs 17 min,P = 0.028; respectively). Sedation, pain, nausea and vomiting, and psychomotor function scores were similar in the two groups. Use of opioid boluses and vasopressors were similar.ConclusionThe use of sevoflurane for maintenance of anesthesia for prolonged neuroradiological procedures is associated with more rapid early recovery than propofol and is associated with similar side effects. Sevoflurane and propofol can both be recommended for these procedures. The clinical benefit of the more rapid recovery with sevoflurane is unknown.RésuméObjectifLe sévoflurane et le propofol conviennent tous les deux à la neuroanesthésie, mais n’ont jamais été comparés comme agents de maintien lors d’opérations de longue durée, soit de une à cinq heures.MéthodeNous avons étudié 103 patients, selon un protocole international multicentrique, qui ont reçu du sévoflurane ou du propofol pour maintenir l’anesthésie en neuroradiologie interventionnelle. À la suite d’une induction normalisée de l’anesthésie avec du propofol, 53 patients ont reçu du sévoflurane de 1 à 3 % avec 60 % de protoxyde d’azote (N2O) dans de l’oxygène (O2) et 50 patients ont reçu de 4 à 10 mg·kg− 1·h− 1 de propofol avec 60 % de N2O dans de l’O2. Les agents de maintien ont été titrés en regard de la tension artérielle générale (moyenne de la tension artérielle de base ± 20 %). Le temps nécessaire pour récupérer de l’anesthésie, les modifications de la sédation, la douleur, les nausées et les vomissements et l’état de la fonction psychomotrice pendant la récupération ainsi que l’usage de médication de secours ont été les paramètres notés.RésultatsOn a observé qu’avec le sévoflurane la reprise de la respiration spontanée, l’extubation, l’ouverture des yeux et le retour de l’orientation ont été plus précoces qu’avec le propofol (3 vs 4 min, P = 0,01 ; 5 vs 6 min, P = 0,015 ; 7 vs 10 min, P < 0,001; 13 vs 17 min, P = 0,028 ; respectivement). Les scores de sédation, de douleur, de nausées et de vomissements et de fonction psychomotrice ont été similaires chez les patients des deux groupes. L’usage de bolus d’opioïdes et de vasopresseurs a aussi été similaire.ConclusionL’usage du sévoflurane, comparé au propofol, pour maintenir l’anesthésie pendant les interventions neuroradiologiques prolongées, est associé à une récupération plus rapide, mais à des effets secondaires similaires. On peut donc recommander les deux médicaments pour ce type d’opérations. L’avantage clinique de la récupération précoce reliée au sévoflurane n’est pas connu.

Tracheal intubation through the laryngeal mask airway using a gum elastic bougie: the effect of head position

STUDY OBJECTIVE To determine the effect of head position on success of tracheal intubation through a Laryngeal Mask Airway (LMA) using a gum elastic bougie. DESIGN Randomized, controlled study. SETTING Anesthesia and operating rooms of the University Hospital, Nottingham, UK. PATIENTS 20 patients scheduled to undergo routine elective surgery requiring the use of an LMA for anesthesia. INTERVENTIONS Blind placement of a gum elastic bougie through an LMA in two head positions. MEASUREMENTS AND MAIN RESULTS Final position of the gum elastic bougie after removal of the LMA as determined by fiberoptic laryngoscopy. The gum elastic bougie was correctly sited in the trachea in the classical intubating position in 4/20 (20%) and in the neutral position in 0/20 (0%). There was no difference in the success of this technique between the two head positions. CONCLUSIONS This technique cannot be recommended as an alternative to direct laryngoscopy following a failed intubation.