Efficacy and safety of propofol versus midazolam in fiberoptic endotracheal intubation

Abstract

Background:

Fiberoptic intubation is a technique commonly used for difficult airways. Conscious sedation is desirable to make this procedure tolerable, and it is essential that patients are cooperative, relaxed, and comfortable especially when difficult airway anatomy or pathology is encountered.

Objective:

To compare the safety and efficacy of propofol versus midazolam in oral fiberoptic endotracheal intubation in terms of hemodynamic changes, level of sedation, ease of intubation, and patient comfort and complications.

Materials and Methods:

In a prospective randomized study, 60 patients of age group 18–60 years and American Society of Anesthesiologists health classification of I and II with anticipated difficult intubation were randomly allocated into two groups. Both the groups were premedicated with injection glycopyrrolate 0.005 mg/kg and injection butorphanol 1 mg and nebulized with 4 ml of 4% lignocaine starting 20 min before the surgery. After that patients in Group I received intravenous propofol 1–2 mg/kg to a maximum of 2 mg/kg followed by 20 mg increments if needed and Group II received 0.05 mg/kg midazolam followed by 2 mg increments till the adequate level of sedation was reached. Patients were monitored for hemodynamic parameters, sedation according to observer's assessment of alertness score, intubation score, intubation time, patient comfort, satisfaction score, and complications, if any. Results were statistically analyzed.

Results:

The mean sedation score, patient comfort score, and patient satisfaction were greater in propofol group (P < 0.05) but there were no significant differences in hemodynamics, intubating conditions, and complications.

Conclusion:

We conclude that compared with midazolam, propofol provides better sedation for fiberoptic endotracheal intubation and better patient comfort and satisfaction.

INTRODUCTION

To secure and maintain a patent airway is one of the prime roles of anesthesiologists. Tracheal intubation is one of the best methods of securing a patient's airway. Tracheal intubation, usually simply referred to as intubation, is the placement of flexible plastic tube into the trachea to maintain an open airway. It is frequently performed in critically injured, ill, or anesthetized patients to facilitate ventilation of the lungs, including mechanical ventilation, and to prevent the possibility of asphyxiation or airway obstruction. The most widely used route is orotracheal, in which an endotracheal tube (ETT) is passed through the mouth and vocal apparatus into the trachea. It can be performed with local or topical anesthesia or with sedation only. Intubation is normally facilitated by using a conventional laryngoscope, flexible fiberoptic bronchoscope, or video laryngoscope to identify the glottis. For sedation, drugs that may be used include fentanyl, midazolam, propofol, dexmedetomidine, and remifentanil. Each drug has advantages and disadvantages. Newer drugs such as remifentanil have disadvantages of narrow therapeutic index and in familiarity regarding infusion kinetics.[1]

Midazolam is a benzodiazepine which acts by binding to receptor complex which facilitates GABA action (major inhibitory neurotransmitter in the brain). Midazolam is water soluble, nonirritant to tissues. It has distribution half-life of 6–30 min and elimination half-life of 1–4 h. Midazolam is metabolized in liver and its metabolite is inactive. Propofol is a sedative/hypnotic which also enhances GABA activity and induces depression of the central nervous system, so it can be used as an alternative to benzodiazepines for intravenous (i.v.) sedation. Propofol has distribution half-life of 2–4 min and elimination half-life ranging from 30 to 60 min. Propofol undergoes hepatic metabolism into four inactive metabolites. Rapid onset and prompt recovery make it an ideal choice for sedation.[2]

Aims and objectives

To compare efficacy and safety of i.v. propofol versus i.v. midazolam in fiberoptic endotracheal intubation.

Following parameters were observed:

• Hemodynamic changes

• Level of sedation according to observer's assessment of alertness (OAA)/sedation score

• Ease of intubation

• Patient comfort

• Side effects and complications.

MATERIALS AND METHODS

In this study, a total of 60 patients aged between 18 and 60 years and of American Society of Anesthesiologists (ASA) Grades I and II scheduled to undergo elective surgery were selected and randomly divided into two groups of 30 each and hemodynamic parameters, intubation scores, ease of intubation, level of sedation, and complications were noted. Patients with reduced cervical mobility (limited capacity to flex or extend the neck), Mallampati classification Grade III or IV, and Wilson score equal to or more than 6 were included.

Patients in both the groups were premedicated with injection 0.2 mg glycopyrrolate and injection 1 mg butorphanol intravenously and nebulized with 4 ml of 4% lignocaine for 10 min starting 20 min before the surgery. Patients in Group I received 1 mg/kg propofol i.v. with 20 mg increments until adequate sedation was achieved and Group II patients received 0.05 mg/kg midazolam i.v. with 2 mg increments till optimum sedation.

The sedation score, intubation score comprising vocal cord movements, cough, and limb movements, intubation time, patient satisfaction score, patient comfort score along with hemodynamic parameters, arterial saturation, electrocardiogram (ECG), and complications were noted.

Observations

The present study has been conducted on 60 patients selected from both sexes between 18 and 60 years of age and ASA class I and II scheduled for elective surgery at the Department of Anesthesia at a tertiary hospital. The patients were divided into two groups of 30 patients each. Group I patients were given propofol, and Group II patients were given midazolam as sedative agents for fiberoptic orotracheal intubation. Fiberoptic orotracheal intubation was done in both the groups. Age, weight, sex, body mass index (BMI), and Wilson score were comparable in Groups I and II. Hemodynamic parameters were recorded which included pulse rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, ECG changes, and SpO₂. The intubation score was noted according to the movement of vocal cords, presence of coughing, and limb movements along with the patient comfort score that included the 5-point fiberoptic intubation score and the 3-point comfort score. Any complication or any other drug used during the procedure was noted. After intubation, routine general anesthesia was administered. After the surgical procedure, each patient was asked to assess his/her experience with awake fiberoptic intubation and patient satisfaction score was noted. A P < 0.05 was considered statistically significant.

The difference in the mean age, sex distribution, and BMI in both the groups was found to be statistically nonsignificant (P > 0.05) [Tables 1–3].

Table 1.

Statistical analysis of age group in both groups

Table 3.

Statistical analysis of body mass index in both groups

Table 2.

Sex-wise distribution

The mean Wilson score in Group I was 4.63 ± 1.47 and in Group II was 5.17 ± 0.91. The values in both the groups were comparable and no significant statistical difference was found [Table 4].

Table 4.

Statistical analysis of Wilson score in both groups

The mean baseline heart rate in Group I was 80.90 ± 9.74 beats/min and in Group II was 80.20 ± 8.73 beats/min. The heart rates in both the groups were compared throughout the procedure and no statistically significant difference was found (P > 0.05) [Table 5 and Graph 1].

Table 5.

Mean±standard deviation of heart rate (beats/min) in Group I and Group II

Graph 1.

Mean ± standard deviation of heart rate (beats/min) in Group I and Group II

The baseline systolic blood pressure in Group I was 125.17 ± 6.59 mmHg and in Group II was 127.93 ± 7.08 mmHg. The two groups showed no statistical difference (P > 0.05) [Table 6 and Graph 2].

Table 6.

Mean±standard deviation of systolic blood pressure (mmHg) in Group I and Group II

Graph 2.

Mean ± standard deviation of systolic blood pressure (mmHg) in Group I and Group II

The baseline diastolic blood pressure in Group I was 81.99 ± 5.39 mmHg and in Group II was 83.77 ± 5.44 mmHg. The two groups showed no significant statistical difference in the readings (P > 0.05) [Table 7 and Graph 3].

Table 7.

Mean±standard deviation of diastolic blood pressure (mmHg) in Group I and Group II

Graph 3.

Mean ± standard deviation of diastolic blood pressure (mmHg) in Group I and Group II

The baseline mean arterial blood pressure in Group I was 96.30 ± 5.79 mmHg and in Group II was 97.90 ± 5.67 mmHg. The two groups showed no significant statistical difference in mean arterial blood pressure (P > 0.05) [Table 8 and Graph 4].

Table 8.

Mean±standard deviation of mean arterial pressure (mmHg) in Group I and Group II

Graph 4.

Mean ± standard deviation of mean arterial pressure (mmHg) in Group I and Group II

The arterial saturation (SpO₂) readings of both the groups were compared. The two groups showed no statistically significant difference in the readings (P > 0.05) [Table 9 and Graph 5].

Table 9.

Mean±standard deviation of SpO₂ in Group I and Group II

Graph 5.

Mean ± standard deviation of arterial saturation (SpO₂) in Group I and Group II

The mean sedation score in Group I was 2.20 ± 0.40 and in Group II was 2.50 ± 0.50, showing significant statistical difference in the two groups (P < 0.05) [Table 10].

Table 10.

Mean sedation score in both groups

The mean intubation score in Group I was 3.86 ± 0.73 and in Group II was 4.23 ± 1.22. The two groups were comparable showing no significant statistical difference (P > 0.05) [Table 11].

Table 11.

Mean intubation score in both groups

The mean time for intubation taken in Group I (propofol) was 4.30 ± 0.59 min and in Group II (midazolam) was 4.56 ± 0.83 min. The mean intubation time in both the groups was comparable and there was no statistically significant difference (P > 0.05) [Table 12].

Table 12.

Mean intubation time in both groups

The mean patient comfort score in Group I (propofol) was 2.36 ± 0.55 and in Group II (midazolam) was 3.00 ± 0.90. The two groups showed a statistically significant difference (P < 0.05) [Table 13].

Table 13.

Mean patient comfort score in both groups

The patient satisfaction score after the surgical procedure in the two groups showed that 90% of the patients in Group I (propofol) had excellent satisfaction as depicted by P < 0.05 [Table 14 and Graph 6].

Table 14.

Patient satisfaction score

Graph 6.

Patient satisfaction score in Group I and Group II

DISCUSSION

The present study has been conducted on 60 patients selected from both sexes between 18 and 60 years of age and ASA class I and II scheduled for elective surgery at the Department of Anesthesia at the hospital. The patients were divided into two groups of 30 patients each. Group I patients were given propofol, and Group II patients were given midazolam as sedative agents for fiberoptic orotracheal intubation. Patients in both the groups were premedicated with injection glycopyrrolate 0.2 mg intramuscularly 30 min before surgery and injection butorphanol 1 mg intravenously immediately before intubation. Patients in both the groups were nebulized with 4 ml of 4% lignocaine for 10 min starting 20 min before the surgery. We did the comparison between propofol and midazolam for efficacy and safety for sedation during fiberoptic endotracheal intubation.

Heart rate

In our study, the mean baseline heart rate in group propofol was 80.90 ± 9.74 beats/min and in group midazolam was 80.20 ± 8.73 beats/min. The heart rate was noted every minute till 10 min, every 5 min till 30 min, and every 10 min for the rest of the duration of surgery and no statistically significant differences were found. No significant differences in the hemodynamic parameters were found in previous similar studies done by various authors.[3,4]

Blood pressure

The systolic blood pressure showed no significant statistical difference among the two groups during fiberoptic bronchoscope insertion and during ETT placement. The mean systolic pressure in group propofol was 125.17 ± 6.59 mmHg and in group midazolam at baseline was 127.93 ± 7.08 mmHg. The readings were taken for every minute till 10 min, every 5 min till 30 min, and every 10 min for the rest of the duration of surgery and no statistically significant differences were found.

The readings for diastolic blood pressure and mean arterial blood pressure were also taken at 1 min till 10 min, every 5 min till 30 min, and every 10 min till the end of surgery and no significant statistical differences were found in both the groups. The baseline mean diastolic blood pressure and mean arterial pressure for group midazolam were 83.77 ± 5.44 mmHg and 97.90 ± 5.67 mmHg, respectively, and for group propofol were 81.99 ± 5.39 mmHg and 96.30 ± 5.79 mmHg, respectively. Similar results matching as that of our study were found in other studies done by various authors.[3,4,5,6]

Arterial saturation

SpO₂ measurements were done in both the groups during premedication, sedation, fiberoptic intubation, and throughout the rest of the surgery. The baseline arterial saturation in group midazolam was 99.47 ± 0.68 and 99.40 ± 0.62 in group propofol. No significant statistical difference was found in comparing both the groups. There were no episodes of arterial desaturation in patients in either of the groups. Similar results were found in respective studies done by Falkman et al.[4] and Lee et al.[5]

Sedation score

Sedation was monitored in both the groups according to the OAA score. Fiberoptic orotracheal intubation was done after achieving adequate sedation levels (OAA ≤3). The optimum level of sedation was achieved earlier and was deeper in group propofol as compared to group midazolam. Once the adequate sedation level was achieved, fiberoptic orotracheal intubation was successful in all the patients. The mean sedation score in group propofol was 2.20 ± 0.40 and in group midazolam was 2.50 ± 0.50 showing more satisfactory levels of sedation with propofol (P < 0.05). Similar results were observed by various other authors in their respective studies.[3,5,7,8]

Intubation score

The intubation score was calculated for both the groups that was assessed by noting vocal cord movement, coughing, and limb movements. The mean intubation score in group midazolam was 4.23 ± 1.22 and in group propofol was 3.86 ± 0.73. No significant statistical differences were found in terms of intubation score showing similar intubating conditions (P > 0.05). The vocal cord scores were favorable in group propofol, however not statistically significant (P > 0.05). These results coincide with the study conducted by Lee et al.[5] and Falkman et al.[4]

Intubation time

Fiberoptic orotracheal intubation was attempted in both the groups after attaining adequate preparation and sedation levels. Although the sedation levels were achieved earlier in group propofol, the mean time for performing endotracheal intubation showed no significant difference (P > 0.05). The mean intubation time in group propofol was 4.30 ± 0.59 min and 4.56 ± 0.83 min in group midazolam. Similar results as that of our study with mean intubation time were obtained by Falkman et al.[4] and Lee et al.[5] in their respective studies.

Intubation attempts

After achieving the optimum sedation level, fiberoptic orotracheal intubation was successful in all the patients in both the groups. About 96.7% patients in group propofol were intubated in the first attempt; however, 83.3% patients in group midazolam were intubated in the first attempt. Five patients in group midazolam required another attempt for intubation showing better sedation and patient tolerability in group propofol.

Patient comfort score

At the time of fiberoptic scope insertion and subsequent intubation of the trachea, the patient comfort score was evaluated by the anesthesiologist in both the groups by noting the 5-point fiberoptic intubation score (1 - no reaction, 2 - slight grimacing, 3 - heavy grimacing, 4 - verbal objection, and 5 - defensive movement of hands and legs) and 3-point comfort score (1 - cooperative, 2 - minimal resistance, and 3 - severe resistance). The lowest mean comfort score was recorded with group propofol as compared to group midazolam. The mean patient comfort score in group propofol was 2.36 ± 0.55 and in group midazolam was 3.00 ± 0.90, thereby showing better patient comfort with group propofol. Clark et al.[8] in their study also found better tolerance with group propofol. Clarkson et al.[3] in their study however found no significant difference in patient tolerance between the study groups. Hence, our study coincides with the study performed by Clark et al.[8]

Complications

There were no serious complications (laryngospasm, cyanosis, or bleeding from airway). However, coughing was noted in both the groups during fiberoptic bronchoscopy and ETT placement, but there was no statistically significant difference in both the groups (P > 0.05).

Patient satisfaction score

While comparing the patient's satisfaction score in our study (1 - excellent, 2 - good, 3 - reasonable, and 4 - poor), it was found that there was a significant statistical difference between the two groups. The patients in group propofol showed better satisfaction score. Ninety percent patients in group propofol had an excellent satisfaction score whereas only 60% patients in group midazolam had excellent satisfaction. These findings coincide with the study done by various authors in their respective studies.[4,9,10]

CONCLUSION

In our study, we conclude that propofol is a better sedative agent for fiberoptic intubation and provides better patient satisfaction in comparison to midazolam with similar hemodynamic profile, intubating conditions, and rate of complications. Midazolam has been shown to have adverse hemodynamic and airway stability when combined with another sedative/hypnotic,[11,12,13] but when used alone it appears to be quite reassuring.[4,5] By using a median sample size, this study supports the observations made by various other authors in previous similar studies. We expect the present study to add to the existing knowledge on this subject.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.