Evaluation of different anaesthetic techniques for insertion of laryngeal mask airway in cardiac patients undergoing urgent retinal surgery

ABSTRACT

Forty-five ASA I and II adult patients scheduled for urgent retinal surgery were included in the study after giving a written informed consent. Patients were randomly divided into three equal groups; 15 patients each Group P [propofol group], group S [sevoflurane group] and group MT [midazoIam-thiopentone group]. Induction of anaesthesia was done by propofol in group P in a dose of 3 mg.kg[-1] while 8% sevoflurane in 50% nitrous oxide in oxygen was used for induction in group S. In-group MT, midazolam was given iv in a dose of 0.1 mg.kg[-1] followed after three minutes with thiopentone in a dose of 5 mg.kg[-1]. The laryngeal mask airway [LMA] was inserted using the standard method described by Brain. The three groups were comparable as regards age, weight, gender and type of surgical procedures. There were significant decrease in heart rate, MABP, and CI compared with baseline values in group P and group MT [P<0.05]. There was insignificant difference between the three groups as regards percentage of patients with excellent to satisfactory quality of LMA insertion being 90%, 85%, and 95% in group P, S, and MT respectively. Time of insertion of LMA was significantly shorter in propofol group compared with the other two groups [P<0.001]. The number of attempts of insertion of LMA was significantly higher in sevoflurane group. The percentage of patients who received additional propofol doses was significantly less in sevoflurane group compared with other two groups [P<0.05]. During trial of insertion of LMA, it was successfully inserted in high percentage of patients in the first minute in both propofol and midazolam-thiopentone groups compared with sevoflurane group [P<0.001]. The incidences of cough, laryngeal spasm and inadequate jaw relaxation were higher while the duration of apnoea was significantly shorter in sevoflurane group compared with the other two groups [P<0.001]. There was insignificant difference between the three groups as regards the incidences of hiccough, head movement, and bronchospasm. It could be concluded that the use of sevoflurane-N[2]O for insertion of LMA in cardiac patients was associated with greater degree of haemodynamic stability. The ease and quality of insertion of LMA was comparable between the three groups. The time for insertion of LMA using sevoflurane -N[2]O was longer but the incidence of respiratory depression was less compared with the other two groups