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A Comparative Blind Study for Assessment of Intubating Conditions Using Propofol and Remifentanil with and Without Muscle Relaxant

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A Comparative Blind Study for Assessment of Intubating Conditions Using Propofol and Remifentanil with and Without Muscle Relaxant Alexandria Journal of Anaesthesia and Intensive Care A Comparative Blind Study for Assessment of Intubating Conditions Using Propofol and Remifentanil with and Without Muscle Relaxant Dr. Ashraf A. Hassan*,Hefny M Hefny *Department of Anesthesia, Faculty of Medicine, University of Alexandria, Alexandria, Egypt. ABSTRACT Background: Remifentanil is a powerful and ultra-short acting opiate, with a rapid onset of action. It is hydrolyzed by non-specific blood and tissue esterases and it has a half life of approximately 3 min compared with 58.5 min for alfentanil after 4 hours infusion. Thus, remifentanil can be administered without fear of accumulation over time. Intubation without neuromuscular blocking agents has been used in a number of different studies. Based on the pharmacokinetic profile of remifentanil, it was hypothesized that it may be very useful in facilitating tracheal intubation. The aim of our study is to determine the quality of intubation using remifentanil 3µg/kg and propofol 2 mg/kg compared with the standard use of muscle relaxants. Methods: We studied 100 healthy adult patients (ASA physical status I, II), undergoing elective surgery requiring tracheal intubation. They are arranged in two equal groups: one group with muscle relaxation given for intubation, while the other group no relaxant was given. Anesthesia was induced with 3µg.kg-1 of remifentanil over 3 min. followed by propofol 2mg.kg-1 as a bolus over 30 seconds for both groups. Laryngoscopy was performed after assisted ventilation with 50% N2O and 6-8% desflurane in O2till a bispectral index value (BIS) of < 40% was reached. The trachea was intubated with an appropriate-sized cuffed tube. The study parameters were; MAP, HR, and SpO2 which were measured before induction, then every minute until the tube is fixed. A blinded operator scored the ease of intubation using a special scoring system. Adverse events such as laryngospasm, bronchospasm, chest wall rigidity, coughing or post-operative sore throat were recorded if occurred. Results: intubation conditions were clinically acceptable in both groups with no statistical difference. Conclusions: From this study we conclude that the use of propofol and remifentanil in the given doses provided excellent intubation condition without the need for muscular relaxation. Key words: remifentanil, propofol, intubation. INTRODUCTION approximately 3 min. compared with The ease of endotracheal intubation has 58.5min. for alfentanil after 4 hours been recently shown to affect the incidence infusion(3,4). The terminal half life is less of laryngeal injuries(1). Thus, routine use of than 10 min at the site of action with a rapid muscle relaxants has become the gold termination of effect(5,6). These properties of standard in routine anesthesia practice to remifentanil produce a rapid onset with a facilitate smooth tracheal intubation. time to peak plasma concentration effect of However, the use of muscle relaxants is not 60 – 90s.only(7). The offset of remifentanil is free of complications, for example they are quick and dramatic, with the loss of implicated in many cases of anaphylaxis (2), effective analgesia occurring within minutes the concerns about their prolonged effects; of cessation of infusion. Thus, remifentanil especially in elderly, or in patients with can be administered without fear of organ dysfunction, and lastly their potential accumulation over time. trigger of malignant hyperthermia. Intubation without neuromuscular blocking Remifentanil is a powerful and ultra- agents, has been used in a number of different short acting opiate, with a rapid onset of studies(8,9,10). Given the pharmacokinetic profile action. It is hydrolyzed by non specific blood of remifentanil, it was hypothesized that it may and tissue esterases, it has a half life of be very useful in facilitating tracheal intubation. AJAIC-Vol. (9) No. 1 Marsh 2006 Alexandria Journal of Anaesthesia and Intensive Care A lot of results compared alfentanil and cisatracurium injected i.v. in a dose of 0.2 remifentanil for intubation (11) have been mg Kg-1, followed by face mask assisted recorded. Also,some studies have been ventilation with 8% desflurane in 50% N2O performed to describe the effect of using in oxygen for 2 min. different doses of remifentanil with propofol in In muscle relaxants free group, order to assess intubation conditions (5,12). anesthesia was induced with 3 µg kg-1 of The aim of our study is to determine the remifentanil over 3 min. followed by quality of intubation using remifentanil 3 propofol 2mg.kg-1 as a bolus over 30 s, then µg.kg-1 with propofol 2 mg.kg-1; and to face mask assisted ventilation with 8% compare it with the standard use of muscle desflurane in 50% N2O in oxygen was relaxants. applied. Induction was considered complete if BiS index value was less than 40. METHODS After obtaining ethics committee approval Endotracheal intubation. and written consent, we studied 100 healthy After the induction was considered adult patients aged from 18-45 years (ASA complete another anesthesiologist was physical status 1, 2), undergoing elective called to proceed through the process of surgery requiring tracheal intubation in Zayed endotracheal intubation; he was blinded to Military Hospital-Emirates. The airway was which group he was intubating to avoid assessed using a modified Mallampati test, as personal bias. Laryngoscopy was done described by Samson & Young (13). Exclusion using blade sizes of 3 or 4 of Macintosh criteria were; a history of esophageal reflux or larngoscopy. Patient trachea was intubated hiatus hernia, previous difficulty with using low pressure cuff tracheal tube 7.5 intubation or difficult airway as suspected mm for men and 7.0 for women. The cuff when there is one or more of the following: was inflated smoothly to 20-30 Cm H2O, Mallampati classification > 2, interincisor controlled with help of intra cuff pressure distance <3.5 cm or thyromental distance < guide (Mallinckrodot Medical, Athlone, 6.5cm, and when there is renal or hepatic Ireland. ETT cuff air pressure gauge). impairment. Anesthesia was maintained with 6-8% Patients were undergoing surgery for desflurane in 50% N2O in oxygen. orthopaedic, urology, plastic and general Ventilation was assisted to maintain surgery and were all premedicated with normocapnia. midazolam 0.02mg Kg-1 i.v. 10 min. before induction. Patients then were randomly Parameters of study arranged in two equal groups (50 patients In our study, MAP, HR, and SpO2 were each). For the first group muscle relaxants measured before induction, then every minute were planned to be given to facilitate until the tube is fixed. The operator scored the tracheal tube insertion, but in the other ease of intubation using the scoring system group muscle relaxants were not used for shown in table 1. The view of the larynx was intubation. assessed with the modified Cromack and Once in the operating room, monitoring Lethane classification (14). of ECG, heart rate (HR), peripheral arterial Adverse events such as laryngospasm, hemoglobin oxygen saturation (SpO2), and bronchospasm, chest wall rigidity, airway non invasive mean arterial blood pressure trauma, coughing in response to (NMAP) were commenced. Bispectral index laryngoscopy, tube insertion or inflation of (BiS, Aspect Medical Systems, USA) to cuff were recorded. Postoperative horsiness monitor the depth of anesthesia was also or throat pain was recorded by direct patient used. questionnaire next morning. Induction- related hypotension which was defined as > Induction of general anesthesia. 20% reduction of mean arterial blood In the muscle relaxant group, after 3 min. pressure from the pre-operative basal of pre-oxygenation, anesthesia induction levels-was recorded too. Induction related started with 3 µg Kg-1 of remifentanil i.v. hypotension if happened was treated by i.v. injection over 3 min. followed by i.v. injection of fluids and / or ephedrine 5 to 10 mg i.v. propofol 2mg Kg-1 over 30 seconds; then boluses. AJAIC-Vol. (9) No. 1 Marsh 2006 Alexandria Journal of Anaesthesia and Intensive Care Statistical Analysis patients of relaxant group (6%) and 11 Intubation score data were considered patients in relaxant free group (22%) P categorical variables; they were analyzed <0.05 (Table 4). using X2- test. P<0.05 was considered nduction related hypotension was significant. The mean arterial blood pressure noticed in 20% of relaxant group and 22% and heart rate values were analyzed for of relaxant free group with no significant differences among pre-induction, post- difference between the two groups. induction and post-intubation values using Bradycardia which is defined as a pulse repeated-measures analysis of variance rate < 60 beats /min. occurred in 6% of (ANOVA test). P value <0.05 was considered patients of relaxant group and 8% of statistically significant. patients of relaxant free group with no significant difference between the two RESULTS groups. A hundred patients were enrolled into egarding SpO2, it was above 97% in all the study. Fifty patients enrolled in each patients of the study with no single group. Patient characteristics are shown in recording of hypoxia during the period of table 2; while surgical procedures done the study. Two patients (4%) of relaxant presented in table 3. free group coughed during cuff inflation Intubation was completed successfully while one patient (2 %) of relaxant group in all patients with no intubation failures in coughed during cuff inflation with no both groups. significant difference between the two Clinically acceptable intubation scores groups. were observed in 49 patients (98%) of ostoperative throat pain recorded in 5 relaxant group and in 48 patients (96%) in patients (10%) of relaxant group and in 6 relaxant free group with no significant patients (12%) in relaxant free group with difference. Laryngoscopic view before no significant difference between the two external laryngeal pressure proved to be groups. difficult (McCormack grades 3 or 4) in 3 Table (1): Scoring conditions for tracheal intubation.
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