IJCRR

IJCRR - 4(14), July, 2012

Pages: 131-147

Date of Publication: 31-Jul-2012

A PROSPECTIVE RANDOMIZED STUDY TO COMPARE SEVOFLURANE WITH PROPOFOL FOR LARYNGEAL MASK AIRWAY INSERTION IN PAEDIATRIC PATIENTS

Author: Savita Choudhary, Seema Gandhi, Arvind Kumar Yadav

Category: Healthcare

Abstract:Objective: The present study was done in paediatric patients to compare sevoflurane with propofol inductions for quality and ease of insertion of Laryngeal mask airway (LMA). Methods: The present prospective randomized study was carried out in a tertiary care teaching hospital. Sixty premedicated patients of 3-12 years of age were randomly assigned to two equal groups. In propofol group, injection propofol 3mg/kg intravenous, and in sevoflurane group 6-7% sevoflurane inhalation in 4 lit/min O2 were given. Parameters of comparison were time of induction, time of successful insertion, insertion conditions, number of attempts, ease of insertion, hemodynamic parameter, and postoperative complications. All data were analyzed using paired t-test and chi-square test. P values calculated and P< 0.05 was considered significant. Results: The mean time for induction was 45.93 \? 5.58 seconds for sevoflurane group and 45.2 \? 6.07 seconds for propofol group. Insertion time for sevoflurane group (106.7 \? 17.64 sec.) was higher than the propofol group (77.23 \? 22.73 sec.) with P value < 0.001, which
was statistically significant. It was slight easier to insert LMA in sevoflurane group compared to propofol
group. In sevoflurane group overall insertion condition was excellent in 76.66%, satisfactory in 20% and
poor in 3.33% as compared to propofol group which was 66.66%, 26.66%, 6.66% respectively. The result
was statistically not significant. Both groups exhibited stable hemodynamic profile. Post operative complications in both groups were not significant. Conclusion: Sevoflurane is an equally good alternative to propofol for insertion of LMA in paediatric patients.

Keywords: Laryngeal mask airway (LMA), Sevoflurane, Propofol, Induction

Full Text:

INTRODUCTION
The most important role of an anaesthesiologist is to control the airway particularly in paediatric age group who is more vulnerable to life threatening hypoxia. Laryngeal mask airway (LMA) offers some of the advantages of tracheal intubation while avoiding the fundamental disadvantages by eliminating the necessity of visualizing the larynx and penetrating the laryngeal opening.[1, 2] It is safe and preferred in many procedures that are unique to children and require multiple administration of anaesthesia in short interval. Thus LMA serves as effective bridge between facemask and endotracheal tube.[3, 4] Insertion of LMA requires sufficient depth of anaesthesia for suppression of airway reflexes.[5] Among the intravenous induction agents, propofol offers a smooth and rapid induction, potent in depressing the airway reflexes, and emergence is devoid of delirium.[6] Propofol has been proved superior to other intravenous agents in insertion of LMA and has been recommended as induction agent of choice in LMA insertion when used with midazolam and fentanyl.[7, 8] Among inhalation agents, sevoflurane a halogenated volatile agent, has pleasant odour, non-pungency and low blood gas solubility which allows rapid and smooth induction with good recovery characteristics and excellent hemodynamic stability.[5, 9] Its pleasant odour and lack of discomfort coupled with fast induction makes it a highly popular induction agent in paediatric anaesthesia. A high inspired concentration for induction provides good conditions for insertion of LMA.[10-13] LMA have become widely used device in practice of anaesthesia; so it becomes imperative to search an ideal induction agent in LMA insertion. Propofol has been used as induction agent of choice since long time. Growing studies now available comparing sevoflurane ?halogenated volatile agent‘ with propofol. Very few studies were done in paediatric patients in India and no study was done in our institute. So, the present study was done in paediatric patients to compare sevoflurane inhalation induction with propofol intravenous induction for insertion of LMA in a tertiary care teaching hospital. MATERIALS AND METHODS The present study was carried out in a tertiary care teaching hospital. Hospital ethics committee approval was obtained before commencing the study. Informed and written consent was obtained from parents. Sixty patients of 3-12 years of age with ASA grade I or II posted for minor and short duration (anticipated time <60min) procedures which can be conducted under LMA anaesthesia were included in study. Patients having clinically significant cardiovascular, pulmonary, renal or hepatic disease, patients with oropharyngeal pathology, patients with limited mouth opening, laproscopic procedures, hypersensitivity to halogenated anesthetic agents were exclude from the study. It was a prospective randomized study. Patients were randomly assigned to one of two treatment groups: Group S (n1=30) received inhalational induction with sevoflurane. Group P (n2=30) received injection propofol intravenously. A proper pre-anesthetic check up was performed one day before and on the morning of surgery. Clinical history was obtained and physical examination done including weight, mouth opening etc for selection of patients. Basic routine investigations like haemogram, renal function test, serum electrolytes, random blood sugar, chest xray etc were advised and recorded. In operation theatre after taking informed consent and confirming adequate preoperative fasting, monitors like ECG, SpO2, and NIBP were applied and base line vital parameters were recorded. Intravenous line was taken and infusion of crystalloids started. Intravenous premedication in the form of Inj. Glycopyrrolate 4µg/kg, Inj. Ondansetron 0.1mg/kg, Inj. Fentanyl 2µg/kg and Inj. Midazolam 0.02mg/kg were given. Adequate preoxygenation with 100% oxygen for 3 minutes was done. In Propofol group, anaesthesia was induced with Inj. Propofol 3mg/kg (incremental dose of 0.5mg/kg given if required). In Sevoflurane group, circuit was primed with 6-7% Sevoflurane in 4 lit/min O2 and patients induced with gas oxygen and sevoflurane. The induction time was noted in all patients from the time of start of drug administration (either sevoflurane or propofol) to the onset of loss of consciousness (loss of eye reflex). After achieving proper relaxation of jaw, insertion of appropriate size of LMA was attempted. Ease of insertion, coughing and gagging, laryngospasm or any airway obstruction and patient movement were evaluated in all patients and score was given accordingly. Scores attributed for condition of insertion of LMA was following; jaw opening (full 3/ partial 2/ nil 1), ease of LMA insertion (easy 3/ difficult 2/ impossible 1), coughing and gagging (nil 3/ moderate 2/ vigorous 1), laryngospasm / airway obstruction (nil 3/ partial 2/ full 1), and patient movements (nil 3/ moderate 2/ vigorous 1). All the scores with regard to insertion condition were summed up and were classified as Excellent if score = 15, Satisfactory if 13-14 or Poor if score <13. In all patients positioning of LMA was checked. In patients whom position of LMA was found unsatisfactory; it was removed and intubated with proper size endotracheal tube. Such incidences were regarded as failure. The time taken for insertion was defined as time taken from start of induction to successful placement of LMA. In both group, anaesthesia was maintained with sevoflurane in 50% O2 and 50% N2O with or without nondepolarizing muscle relaxant. Heart rate, blood pressure and SpO2 were monitored throughout surgical procedure. These vitals were recorded at following stages: Base line, premedication, induction, insertion of LMA, 1, 2, 3, 5, 10, 30 minutes then at every 15min. At the end of procedure, all anaesthetic agents were discontinued, and 100% oxygen was given. Residual neuromuscular blockade was reversed with glycopyrrolate (8 µg/kg i.v.) and neostigmine (50 µg/kg i.v.). As patient became fully conscious and able to open mouth, LMA was deflated and removed gently and surface checked for any presence of blood. Patients were observed for any post-operative complications like sore throat, nausea, vomiting, agitation etc. Parameters of comparison for both groups were time of induction, time of successful insertion, insertion conditions, number of attempts, ease of insertion, hemodynamic parameter, and postoperative complications. All data expressed as mean values ± SD and analyzed using paired t-test and chi-square test. P values calculated and P<0.05 was considered significant. OBSERVATION AND RESULTS In this study 60 patients of ASA I-II were allocated randomly in to group S [n1=30] and group P [n2=30]. Demographic details of the patients were comparable with no significant difference in both the groups. There was no significant difference in induction time among both groups. Insertion time for sevoflurane group was higher than the propofol group with P value <0.001 which was statistically significant. (Table 1) It was slight easier to insert LMA in sevoflurane compared to propofol having score of 2.86 in group S vs 2.73 in group P. Jaw opening was slightly better in group P which is 2.93 as compared to 2.9 in group S. Incidence of coughing/gagging and laryngospasm were very low in both the groups. Incidence of patient movement was more in group P for which incremental dose of propofol was given in four patients. Score for patient movements was 2.96 in group S vs 2.86 in group P. Average score in sevoflurane group was slightly higher i.e.14.61 as compared to propofol group which was 14.41 out of 15. (Figure 1) In group S overall insertion condition was excellent in 76.66%, satisfactory in 20% and poor in 3.33% as compared to group P which was 66.66%, 26.66%, 6.66% respectively. The result was statistically not significant. (Table 2) Twenty seven patients in group S was successfully inserted in 1st attempt while in group P, it was 25 patients. There was difficulty in placement of LMA in one patient of group S and two patients in group P, these patients were intubated. The overall success rate was 96.66% in group S as compared to 93.33% in group P which was not statistically significant. (Figure 2) Both group exhibited stable hemodynamic profile. There was no significant change found in SBP in both the groups except the statistically significant difference was observed at only 2‘ post LMA interval between two groups where fall in SBP (systolic blood pressure) was more in propofol group (P value 0.05). Heart rate at different time periods in both the groups was almost similar. There was no significant difference at any given point of observation for heart rate in both groups (P value >0.05). The arterial oxygen saturation showed parallel changes in both the groups and statistically insignificant. (Table 3) Post operative complications like nausea-vomiting, agitation, sore throat and blood on LMA were found in some patients in both groups but not significant. (Table 4).

DISCUSSION
LMA provides a safe and effective form of airway management for infant and children both for controlled and spontaneous ventilation. LMA fills a niche between face mask and endotracheal tube in terms of both anatomical position and degree of invasiveness. LMA produces lower hemodynamic instability during placement as they avoid stimulating the infraglottic structures.[2] When compared to endotracheal tube, LMA is easy to place, does not require any muscle relaxant as well as laryngoscopy there by prevents complications associated with laryngoscopy and endotracheal intubation.[14] LMA is tolerated at lower  anaesthetic concentrations than the tracheal tube which allows earlier emergence from anaesthesia.[15] Amongst the commonly used IV agents, propofol offers a smooth and rapid induction. Propofol is known to be potent in depressing the airway reflexes, its antiemetic properties and low incidence of euphoria on emergence, thus facilitating LMA insertion.[6, 14, 16] Amongst the inhalation agents, sevoflurane has pleasant, non pungent odor and minimal respiratory irritant features which makes it suitable for insertion of LMA.[17] It has low blood gas partition coefficient (0.66) which provides rapid and smooth induction and recovery from anaesthesia.[6, 11, 17] It has excellent hemodynamic stability which is suitable for paediatric patients.[11] This profile makes sevoflurane the agent of choice for inhalation induction in paediatric anaesthesia. The present study was conducted to compare Sevoflurane inhalation induction with Propofol intravenous induction for placement of LMA in paediatric patients of ASA I-II posted for elective surgeries of shorter duration. All patients in our study were demographically similar in both the groups. There were no statistically significant intergroup variations regarding age, body weight, and gender distribution. Induction time In our study induction was equally fast in both sevoflurane group (45.93 ± 5.58 seconds) and for propofol group (45.2 ± 6.07 seconds), which was not statistically significant. Our study was in agreement to that of Kah L et al study which also observed fast induction in both groups.[10] Two studies reported faster induction with propofol compared to sevoflurane.[18, 19] This could be because of using tidal volume ventilation technique. In contrast to our finding two studies reported faster induction with sevoflurane compared to propofol.[12, 20] A high inspired concentration provides good conditions for the insertion of the LMA.[12] Induction with sevoflurane 8% rather than 3% significantly reduced the second stage of anaesthesia without adversely affecting hemodynamic stability in paediatric patients. Time for insertion In our study the time of insertion was higher in sevoflurane group (106.7 ± 17.64 sec.) compared to propofol group (77.23 ± 22.73 sec.), which was statistically significant. This can be attributed to the initial difficult jaw opening with sevoflurane. The result of our study was comparable to other studies which also observed significantly longer time of LMA insertion in sevoflurane group than in propofol group. [10, 12, 19, 21, 22] While Koppula RK et al study reported similar time in both the groups.[20] In contrast to our study Gil ML et al study observed shorter insertion time with sevoflurane.[11] Insertion condition The ease of insertion was higher with sevoflurane as compared to propofol, while jaw opening was slightly better in propofol group. Similar results were found in other studies which also failed to elicit a significant difference.[5, 21] Most of other studies showed longer time for jaw relaxation with sevoflurane when compared to propofol.[19, 22] The likely explanation for the poor mouth opening in our patients is the lag time during which the alveolar concentration of sevoflurane equilibrates with the brain, which results in inadequate anaesthesia for early insertion. This is supported by the fact that the LMA was eventually inserted in most of the patients and conditions were equally good in both the groups. Furthermore, relaxation of the jaw muscles sufficient for a jaw thrust may be a reflection of adequate depth of anaesthesia. However this is unlikely to be important with sevoflurane because of its low blood gas partition coefficient. Another possible explanation for the difference could be that equipotent doses of both drugs could not be determined. A third possibility is related to the anaesthetics themselves. Propofol is known to have a relaxant effect on jaw muscles, whereas inhaled anaesthetics may cause increased muscle tone and spasticity. The incidence of coughing/gagging was low in both the groups. Incidences of Laryngospasm were very low and essentially similar in the both groups. The patient movements were more with propofol as compared to that with sevoflurane. Similar results were reported by another study.[19] Two other studies found slightly higher incidence of limb movement in sevoflurane in contrast to propofol.[12, 22] In our study sevoflurane induction was not associated with significant excitatory activity because of higher concentration used in our study. Koppula RK et al study reported almost similar insertion condition in both groups.[20] Unlike, Priya V et al study found excellent condition in propofol group with statistically significant difference.[13] In contrast to our study some studies reported a significantly higher number of adverse events during LMA insertion in both groups.[5, 12, 18, 21] This can be attributed to the fact that they did not use any premedication. One study observed a higher adverse events during insertion using propofol but not of statistical significance.[10] Successful attenuation of the laryngeal reflexes is essential to reduce the incidence of respiratory complications during LMA insertions. Propofol is known to depress laryngeal reflexes and facilitate LMA insertion. However, sevoflurane preserves laryngeal reflexes at values up to 1.8 MAC.[23] Sevoflurane may depress laryngeal reflexes at the higher MAC values achieved in our patients. Number of attempts of LMA insertion and Success rate The average number of attempts for insertion in our study was 1.10 for sevoflurane group and 1.14 for propofol group which was not statistically significant. The result of our study was comparable to other study which also reported similar average number of attempts.[18] This was in contrast to other studies which reported less number of attempts with propofol compared to sevoflurane.[10, 19] In our study the 1st time success rate was higher in sevoflurane (90%) compared to 83.33% in propofol which was comparable to that of Joo HS et al study which also reported higher mean 1st time success rate with LMA.[24] With regard to the first time insertion success rate, this study found a significantly higher success rate in the propofol group in contrast to that other studies.[10, 19] Overall success rate for LMA insertion was good in both the groups which was not statistically significant. The results of other studies were comparable to our study.[13, 18, 19] When compared to these studies slight lower success rate in our study may be multifactorial. Hemodynamic parameters The heart rate was slightly higher in sevoflurane group at all time intervals without any statistically significant difference. Gil ML et al study also observed a higher heart rate with sevoflurane in paediatric patients.[11] Propofol group had a greater magnitude of fall in systolic and diastolic BP after induction but well tolerated by patients. The difference was statistically significant at only 2‘post LMA insertion in systolic BP. Kah L et al study could observe a statistically significant difference only in the 4th and 5th minute post induction.[10] One other study also found a significant difference only in the 3rd minute after induction.[13] Some other studies did not find any significant difference.[11, 19, 21] The arterial oxygen saturation changes were comparable in both the groups and this was in agreement to other studies.[10, 13, 19] Post operative complications Most of the patients of both groups reported a pleasant experience. The incidence of post operative complications like sore throat, nausea vomiting, blood on LMA and agitation were also low and did not reach any statistical significance. The similar incidence of nausea and vomiting in the study groups was in contrast to the perception, that propofol is associated with less vomiting than inhalation agents. Possibly the improved incidence of postoperative nausea and vomiting with propofol as compared to sevoflurane is lost when opoid are added. It is also possible that sevoflurane has less emetic potential. Some studies reported lesser incidence of nausea and vomiting with propofol.[19, 22, 24] Kah L et al study could not find a significant difference between both groups.[10] The agitation in present study was slightly more in sevoflurane group without any statistical significance. Two other studies also observed that agitation during emergence was more common in sevoflurane group.[11, 22] It is possible that the incidence of agitation may be reduced by progressive weaning rather than abrupt cessation at the end of surgery.

CONCLUSION
In this randomized prospective study we observed that speed of induction was almost similar in both groups. Sevoflurane took significantly longer time for insertion of LMA but numbers of attempts were slightly lower as compared to that with propofol. Insertion conditions were similar in both the groups. Hemodynamic stability was maintained in both group but slightly better in sevoflurane. There were very low incidences of post operative complications in either group. Thus sevoflurane is an equally good alternative to propofol for insertion of LMA in paediatric age group.

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