Fentanyl and propofol versus fentanyl and etomidate for the insertion conditions of laryngeal mask airway:A prospective observational study

Introduction

Nowadays regional anaesthesia (various blocks) are being very commonly used along with sedation. Sometimes there arises a need to secure airway in maintaining spontaneous ventilation of the patients. In such scenarios Laryngeal mask airway(LMA) , a supraglottic device is the most preferred device used for airway management in day care surgeries. Smooth and successful insertion of LMA requires an adequate mouth opening and minimised airway reflexes.

Commonly used agents for induction of anaesthesia through LMA include propofol alone and in combination with opioids like fentanyl, butorphanol, muscle relaxants such as mivacurium, atracurium . Other drugs such as midazolam, clonidine, dexemedetomidine, ketamine and lignocaine can also be used.

So far LMA insertion has been facilitated using propofol either with ketamine or fentanyl and various studies have been done to compare the above two combinations . It has been found that fentanyl and propofol combination gives better insertion conditions for LMA as compared to ketamine propofol combination. But the combination of fentanyl and propofol is associated with bradycardia and hypotension therefore it needs to be avoided in cardiovascular-compromised patients. So, it is hypothesized whether a combination of fentanyl and etomidate would provide as good insertion conditions as that of fentanyl and propofol. Thus, with such considerations, the present study has been undertaken to compare the two combinations for insertion conditions of LMA.

Methodology

The present study will be conducted in THE DEPARTMENT OF ANAESTHESIOLOGY , M.Y. HOSPITAL AND MGM MEDICAL COLLEGE INDORE M.P.

Prior to the procedure, pre anaesthetic checkup will be done and Written informed consent will be obtained from the patients for participation in the study after explaining procedure in their local language.

Patient will be advised to be kept nil oral for 6 hours before surgery.

The patient will be allotted to either group A or group B using computer generated randomization table .

In the operation theatre standard monitors (electrocardiogram, noninvasive blood pressure, pulse oximeter and EtCO2) will be attached to the patient and baseline parameters will be recorded .

IV access will be secured using 20G cannula.

Ringer lactate @10ml/Kg will be used to preload the patient.

Patient will be premedicated with inj. glycopyrolate 10µg/kg and inj. midazolam 0.02mg/Kg

Patients will be preoxygenated with 100% oxygen for 3minutes using Bains circuit.

Induction of Anaesthesia will be achieved with Inj. fentanyl (2mcg/kg) + propofol (2mg/kg) intravenously in group A and Inj. fentanyl(2mcg/kg) + etomidate(0.3mg/kg) in group B intravenously.

Once adequate relaxation is achieved, appropriated size classic LMA will be inserted as per standard technique by an experienced anaesthesiologist (>3yrs of experience) and successful insertion will be confirmed using capnography. The insertion conditions will be recorded in terms of-

1. number of attempts required

2. time required to insert LMA

3. ease of insertion of LMA

If ,adequate relaxation is not achieved with initial bolus dose, an additional bolus doses of propofol with 1mg/kg and etomidate with 0.15mg/kg will be given in the respective groups. Total drug dose required will be noted.

Anaesthesia will be maintained by O2 50% +N2O 50% + sevoflurane @2 MAC.

Hemodynamic parameters will be recorded at baseline, after induction, immediately after LMA insertion, at 1 minute, at 3 minutes, at 5minutes and at 10 minutes after LMA insertion and there after every 5mins till end of surgery

Any of Adverse effects as mentioned in table 4 and 5 ,will be recorded and treated as per standard protocol.

If, >2 attempts to insert LMA are required, case will be excluded from the study.

Observation Tables

1.Demographic details

Group A/B
Age (years)
Sex
Weight (kg)
Height (m)
ASA grade
Mallampati grade

2.Insertion conditions

Group A/B
Number of attempts required
Total time taken (in second)
Ease of insertion (easy/ difficult)

3.Hemodynamic parameters

HR spO2 MAP EtCO2
Baseline
After induction
After 1 min.
After 3 min
After 5 min
After 10 min
Every 5 minute till  end of surgery

4.Complications related to study drugs

Group A/ B
Hypotension
Bradycardia
Apnoea
Myoclonus

5.Complications related to airway manipulation

Group A/B
Inadequate jaw relaxation
Gagging
Coughing
Limb movement
Laryngospasm

6. Drug dose required

Group A (propofol)/ group B (etomidate)
Total dose of drug Required(mg)

References

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