Comparison of effects of Fentanyl and Lidocaine versus Nalbuphine and Lidocaine on haemodynamic responses to laryngoscopy and intubation

Laryngoscopy and endotracheal intubation are one of the most necessary steps in general anaesthesia. Both laryngoscopy and intubation produce sympathetic stimulation and cause release of catecholamines leading to increase in heart rate and blood pressure which are classified as pressor response.1

In a healthy patient these changes are well tolerable but in patients having cardiovascular comorbidities, raised intracranial pressure and cerebral vascular anomalies, these haemodynamic changes may be detrimental. Pressor responses after intubation have been associated with cerebral haemorrhage, ventricular arrhythmias, ST-segment abnormalities, pulmonary oedema. These changes are associated with rise in catecholamine levels.2  For non-anaesthetic applications, laryngoscopy and tracheal intubations are also used to maintain airway. Diagnostic direct laryngoscopy and fibreoptic bronchoscopy are frequently utilised. All these methods have the potential to elicit sympathetic responses. A majority of these patients are either critically ill or at increased risk.

This arises concern to attenuate these haemodynamic changes in response to laryngoscopy and intubation.

In past years, various drugs have been used to attenuate the haemodynamic responses to laryngoscopy and intubation like calcium channel blocker3, opioids4-9, magnesium sulphate10, vasodilators11, lignocaine7-9, alpha 2 agonists12 etc. but no ideal agent has been found till date.

Opioids in particular have been reported to be helpful in reducing these cardiovascular responses.

Fentanyl, a synthetic pure μ-receptor agonist and Nalbuphine, a semi-synthetic opioid agonist–antagonist analgesic have been used widely to attenuate the pressor response following laryngoscopy and intubation.4-9 But in few studies it has been reported that Nalbuphine has poor response in this regard as compared to Fentanyl.5,6

Lignocaine has also been used intravenously for attenuating these stress responses by its direct myocardial depressant effect, central stimulant effect, and peripheral vasodilatory effect and it also suppresses the cough reflex, an effect on synaptic transmission.13 Lignocaine is one of the cheapest and safest drugs used widely to attenuate stress response to laryngoscopy and intubation.7-9

Fentanyl along with Lidocaine has shown same effect on pressure response to laryngoscopy and intubation as shown by fentanyl alone.7,8

As nalbuphine has shown poor control on haemodynamic responses to laryngoscopy and intubation as compared to fentanyl, hence it is proposed to assess the haemodynamic effects of fentanyl and lidocaine and compared with the haemodynamic effects of nalbuphine and lidocaine following laryngoscopy and intubation.

Extensive search of literature did not show any study comparing the effects of fentanyl with lidocaine and nalbuphine with lidocaine on haemodynamic responses to laryngoscopy and intubation. Therefore, in the present study, effects of fentanyl with lidocaine and nalbuphine with lidocaine on haemodynamic responses to laryngoscopy and intubation will be assessed and compared.