A Comparative Study of Intubating Conditions between PropofolFentanyl-Midazolam and Propofol-Fentanyl-Lignocaine Groups without Neuromuscular Blocking Agents

INTRODUCTION: Before the early 20th century, tracheal intubation was done for conditions including tumors of the oral cavity and obstruction in the larynx. It was done crudely using fingers as a makeshift laryngoscope and without using any drugs. In 1909, ether anesthesia was introduced for the purpose of tracheal insufflations. In 1913, Rowbotham modified the technique and described a series of cases. These tracheal tubes were wide bore catheters and forceps was used to guide them into the trachea. Before the development of neuromuscular blocking agents, endotracheal intubation was done under deep inhalational anaesthesia with ether. Following this, halothane was used to facilitate tracheal intubation. Nowadays, sevoflurane is the most commonly used drug for inhalational induction in peadiateric age group. In 1942, neuromuscular blocking drugs were first introduced into clinical practice to facilitate tracheal intubation. In 1948 Lewis et al used thiopentone sodium for tracheal intubation without using neuromuscular blocking drugs. His study showed that adequate intubating conditions were achieved using thiopentone sodium alone. Tracheal intubation is usually done with muscle relaxants supplemented with induction agents. Over the past few years, several factors have led the researchers to consider omitting neuromuscular blocking agents for tracheal intubation. Endotracheal intubation was facilitated by the apparent ability of propofol to blunt responses to tracheal stimulation and the availability of the short acting opioids, remifentanil and alfentanil. Tracheal Intubation without the use of neuromuscular blocking drugs were used to assess the airway by laryngoscopy and to ascertain if oxygenation is possible. This technique may be useful in both predicted and unexpected difficult intubation and also in cases where neuromuscular blocking agents are either contraindicated or not required. The side effects of succinylcholine, and also those of non-depolarizing drugs, such as anaphylaxis are avoided. Laryngoscopy and endotracheal intubation are mandatory for most patients undergoing general anaesthesia, which is invariably associated with certain cardiovascular changes such as tachycardia or bradycardia, rise in blood pressure and a wide variety of cardiac arrhythmias. These effects are deleterious in susceptible individuals culminating in perioperative myocardial ischemia, acute heart failure and cerebrovascular accidents. The cardiovascular response to laryngoscopy and endotracheal intubation has been recognized since 1951. The response following laryngoscopy and intubation peaks at 1-2 minutes and returns to normal within 5-10 minutes. Though these sympatho adrenal responses are probably of little consequence in healthy individuals, it is hazardous to those patients with hypertension, coronary heart disease, intra cranial pathology and hyper reactive airways. Various systemic as well as topical agents were used to reduce these untoward hemodynamic responses due to laryngoscopy and intubation. The common strategies adopted are narcotics, vasodilators, beta blockers, calcium channel blockers, lidocaine and other sympatholytics. After the emergence of shorter-acting opioids like remifentanil and alfentanil, these drugs were combined with propofol for successful tracheal intubation without muscle relaxants. These drugs are not yet available in many developing countries. Fentanyl is the opioid commonly available and being used in combination with propofol, lignocaine and midazolam for intubation without muscle relaxants. AIM OF THE STUDY: To compare the intubating conditions and cardiovascular changes (post induction) between fentanyl, midazolam, propofol and fentanyl, lignocaine, propofol groups without using neuromuscular blocking agents. MATERIALS AND METHODS: It is a prospective double blind randomized controlled study. The study was approved by the ethical Committee. Hundred patients undergoing elective general surgical procedure under general anaesthesia with endotracheal intubation were included in this study and randomly divided into two groups. The Surgeons were duly informed about the study. The study was during the period of April 2011 to April 2012 in the Department of Anaesthesiology, Chengalpattu MedicalCollege, and Chengalpattu. Group (M) - Fifty patients received propofol 2.5mg/kg, fentanyl 2μg/kg, midazolam 0.03mg/kg. Group (L) - Fifty patients received propofol 2.5mg/kg, fentanyl 2μg/kg, lidocaine 1.5mg/kg. Inclusion Criteria: 1. ASA I & II, 2. Age 20-50yrs, 3. All cases requiring GA. Exclusion Criteria: 1. Not meeting inclusion criteria, 2. Known and difficult airways, 3. Patients with full stomach, 4. Patients posted for emergency surgery, 5. Hypertension, 6. Diabetes, 7. Ischemic heart disease, 8. Reactive Airway Disease, 9. Allergy to drugs. Randomization was done by draw of lots. The follow up of the Patient and analysis of data were done by personnel blinded to which group belonged to. Drawing of lots for Randomization and preparation of study was prepared by a consultant who took no further part in the study, the anaesthetist performing and scoring the laryngoscopy grading and tracheal intubation was blinded to the randomization group and the rest of the study was conducted by investigator who was blinded to the drug injected. MATERIALS: 1. Inj.Profopol 1% - 10 ml vial, 2. Inj.Fentanyl Citrate – 2ml ampoule, 3. Inj.Glycopyrrolate – 1ml ampoule, 4. Inj.Midazolam – 5ml vial, 5. Inj.Lignocaine Hydrocholoride (xylocard) - 50 ml vail, 6. Disposable 5ml syringes, 7. McIntosh Laryngoscope with 3 and 4 size blades, 8. Endotracheal tubes of varying sizes, 9. Emergency drugs, 10. Difficult Intubation Strategies. STATISTICAL ANALYSIS: Heartrate, mean arterial pressure, intubating conditions score include laryngoscopy, limb movement, vocal cord position, coughing are compared. All recorded data were entered SPSS 16.0V Software for determining the statistical significance. Mean and standard deviation for continuous variable and Percentages are given for categorical variables. Student’s ‘t’ test was used to compare the two groups on mean values of various parameters. Chisq test was used to compare the two groups for categorical variables. P value taken for significance is <0.05. RESULTS: There is no statistical significance in patient characteristics between these two groups (Table X to XIII). The Mallampatti grading, Cormack and lehane laryngoscopy grading, and the laryngoscopic duration was compared in both groups. There is no statistical significance in mallampatti and Cormack – lehane grading between these two groups, the statistical significance was observed in laryngoscopy duration (P value is 0.00). Mask ventilation was easy in all patients. Intubation attempt was successful in all (100%) patients in the M group and in the L group 43 out of 50 patients (86%) had successful intubation. There is no rocuronium requirement in the M group and in the L group seven patients required rocuronium (P value 0.01). Patients who are all received rocuronium were intubated successfully. Overall clinically acceptable intubating conditions was 40 out of 50 patients (80%) in the compared to 28 out of 40 patients (56%) in L group. This difference was statistically significant (P value 0.01) (Table 11). Laryngoscopy was easy in all patients in the M group. Laryngoscopy was difficult in 18 (36%) out of 50 patients in the L group (P value 0.00). seven patients in the L group had closed vocal cords requiring administration of rocuronium before intubation (P value 0.01). Twenty two patients (44%) in the L group had sustained coughing (> 10 s) on intubation compared with the M group 5(10%) although this is statistically significant. P value is 0.00 In the L group 18 patients (36%) had vigorous limb movement compared with no limb movement in the M group (P value is 0.00). Cardiovascular responses to induction and intubation are compared in both groups. There is no significant difference in heart rate of both groups. Statistical significance is not observed between the two groups up to induction (P value more than 0.05). After induction there is significant difference on mean arterial pressure between these two groups till the end of the study (P value less than 0.00). Between these two groups better hemodynamic stability was observed in M group. Oxygen saturation was maintained between 96% - 100% before as well as after induction of anaesthesia and tracheal intubation. There were no episodes of laryngospasm, bronchospasm, masseter spasm, or generalized rigidity were observed. CONCLUSION: I conclude that the propofol – fentanyl – midazolam combination is better compared to propofol – fentanyl – lignocaine combination in providing clinically acceptable conditions for intubation without significant cardiovascular changes without the use of neuromuscular blocking agents. Hence this combination can be a useful alternative technique for tracheal intubation when neuromuscular blocking drugs are contraindicated or need to be avoided.