Effectiveness and Safety of Extubation before Reversal of Neuromuscular Blockade versus Traditional Technique in Providing Smooth Extubation.

BACKGROUND: Traditional extubation often leads to bucking, coughing, and undesirable hemodynamic changes. Extubation just before administering reversal could reduce force of coughing, bucking and may provide better extubation conditions.
AIM OF STUDY: The aim of the study was to assess the incidence of bucking with extubation just before administering reversal of neuromuscular blockade compared to traditional technique of awake extubation. Incidence of coughing during extubation, vomiting/regurgitation, aspiration, hemodynamic changes, postoperative bleeding, and extubation conditions were also assessed. SETTINGS AND
DESIGN: This was a prospective randomized study conducted in a tertiary care institute. SUBJECTS AND METHODS: Forty patients were allocated into two equal groups. In Group E, at the end of surgery, extubation was performed and reversal was administered after extubation. In Group L, reversal was given and patients were extubated in the traditional way. Quality of extubation was assessed using extubation quality score. STATISTICAL TESTS USED: Pearson Chi-square test, Fisher's exact test, and independent sample t-test.
RESULTS: Group E showed significantly lower incidence of bucking (15% vs. 65%) and coughing (10% vs. 45%). Incidences of desaturation and regurgitation/aspiration were comparable. In Group E, 85% of patients did not cough during extubation compared to 50% in Group L. Extubation quality was significantly better in Group E. Although extubation time was significantly shorter in Group E, recovery time was comparable in both groups.
CONCLUSION: Extubation just before reversal of neuromuscular blockade resulted in lesser incidence of bucking and coughing during extubation with lesser postoperative bleeding compared to traditional technique of awake extubation without added risks of regurgitation, aspiration, or delayed recovery. Copyright:

INTRODUCTION

Conventionally, at the end of surgeries under general anesthesia, patients are extubated once fully awake which often leads to bucking, coughing, and sudden fluctuations in hemodynamic parameters. Bucking and coughing during extubation lead to high intrathoracic pressure, venous engorgement, and hematoma formation or increased bleeding following major neck surgeries.[1] Moreover, it increases the risk of aerosol generation and thereby transmission of infections to medical personal.[2] We hypothesized that extubation just before complete recovery from neuromuscular blockade could reduce coughing and bucking during extubation and hence could reduce many complications associated with extubation.

The primary objective of the present study was to assess the incidence of bucking with extubation just before reversal of neuromuscular blockade compared to traditional technique of awake extubation in patients undergoing thyroidectomy under general anesthesia. The secondary objectives were assessment of incidence of coughing during extubation, regurgitation/aspiration, desaturation, laryngospasm, and postoperative hematoma requiring re-exploration. The hemodynamic changes, extubation conditions, and postoperative bleeding into the surgical drain with these two techniques of extubation were also compared.

SUBJECTS AND METHODS

This was a prospective, randomized, single-blinded study conducted after obtaining approval from the institutional ethical committee (IEC-AIMS-2O2O-ANES-O3O dated 09-03-2020) and consent from patients for participation in the study and use of the data for research and educational purposes and was registered in Clinical Trials Registry, India, (CTRI/2020/04/024575). Forty patients aged between 20 and 60 years, of the American Society of Anesthesiologists physical status (ASA PS) Classes I and II, undergoing elective total thyroidectomy in euthyroid status as evidenced by normal serum T3 and T4 were included in the study. Patients with Mallampati score of 3 and 4, those with increased risk of regurgitation and aspiration (inadequate fasting, obesity, pregnancy, achalasia cardia, acid peptic disease, diabetes), preexisting vocal cord palsy, uncontrolled hypertension, bronchial asthma, recent respiratory tract infection, malignant thyroid disease, and those on anticoagulants were excluded from the study [Figure 1]. Study procedures followed the guidelines laid down in the Declaration of Helsinki.

Figure 1

CONSORT

All patients fasted for 6 h for solids and 2 h for clear fluids and received oral pantoprazole 20 mg and metoclopramide 10 mg on night before surgery and morning of surgery with sips of water. Patients were randomly assigned to two equal groups, using a computer-generated randomization program, and allocation was performed by sequentially numbered opaque sealed envelopes.

Enrolled patients were allocated into one of the two Groups E and L. In Group E, once the patients started to take spontaneous breaths at the end of surgery, extubation was performed following which reversal was administered. However, in Group L, reversal was given when patients started taking spontaneous breaths and extubated once fully awake and obeying commands. All patients were tested negative for COVID-19 by reverse transcription-polymerase chain reaction preoperatively within 24 h and anesthesiologists wore N-95 mask, face shield, and disposable surgical gowns in the theater.

All patients received general anesthesia as per a standardized protocol. In the theater, after the establishment of an intravenous line and attaching preinduction monitors for noninvasive blood pressure, electrocardiography, and pulse oximetry, general anesthesia was induced with intravenous fentanyl 2 μg.kg−1 followed by propofol 1.5–2 mg.kg−1 till loss of response to verbal commands. After confirming bag and mask ventilation, vecuronium 0.1 mg.kg−1 was administered. After securing airway, anesthesia was maintained with inhalational agent, oxygen in air (1:1), and isoflurane (1–1.5 end-tidal minimum alveolar concentration [MAC]). Adductor pollicis neuromuscular monitoring with peripheral nerve stimulator was used for supplementing subsequent doses of vecuronium intraoperatively.

Fentanyl was repeated at 0.5 μg.kg−1 every hourly. Intraoperative hypertension or tachycardia (>20% from baseline) was managed with increasing isoflurane to 1.5–2 end-tidal MAC and additional fentanyl bolus of 0.5 μg.kg−1 as appropriate. Paracetamol 1 g was given intravenously approximately an hour before completion of surgery. Last dose of vecuronium was administered approximately half an hour before the end of surgery. Ondansetron 0.1 mg.kg−1 was administered and concentration of inhalational agent was gradually tapered toward the end of the surgery.

Toward the end of surgery, the concentration of inhalational agent was gradually tapered and on completion of skin suturing, the anesthetic gases were discontinued, oral suctioning was done under direct vision, and bag ventilation continued till the patient started taking spontaneous breaths. In Group L, reversal with neostigmine and glycopyrrolate was given once patient started taking spontaneous breaths with a train-of-four ratio of >0.6 and extubated once fully awake and obeying commands with adequate tidal volume. In Group E, on resumption of spontaneous breathing efforts with a train-of-four ratio of >0.6, a well-lubricated nasopharyngeal airway was introduced through the more patent nostril identified preoperatively. Patients were extubated at this point of time and immediately after extubation reversal was administered. Following extubation, breaths were assisted using bag and mask ventilation with 100% oxygen until the patient was fully awake and generating adequate tidal volume.

Quality of extubation was assessed by a 5 point rating scale, extubation quality score [Figure 2a].[3] An assistant who was blinded to the groups evaluated the quality of extubation and the respiratory complications (breath holding, laryngospasm, bronchospasm, hypoxemia, and need for reintubation).

Figure 2

(a) Extubation quality scores, (b) Scores of Group E and L

The incidence of bucking and coughing during extubation, postoperative hematoma requiring re-exploration, regurgitation and/or aspiration, and volume of bleeding into the surgical drain at 24 h postoperatively were assessed. Bucking was defined as a forceful and prolonged cough which imitated a Valsalva maneuver. Heart rate and mean arterial pressure (MAP) were recorded at the end of surgery, 1, 3, and 5 min after extubation. Time taken for extubation was calculated from discontinuing inhalational agent to extubation, and recovery time was calculated from extubation till there was response to verbal commands such as opening eyes and protrusion of tongue. The end-tidal isoflurane MAC at extubation and total intraoperative fentanyl consumption were noted in both groups. Signs of aspiration were assessed by auscultation and by respiratory symptoms.

As literature search did not provide any similar study, we initiated the study as a pilot one with 10 patients in each group assessing the incidence of bucking at extubation in early versus late extubation. With an incidence of 72% bucking in late extubation versus 16% in early extubation group, with 95% confidence interval and 90% power, the minimum sample size required to obtain statistically significant result was calculated to be 14 per group. We included 40 patients in our study with 20 patients in each group during our study period.

Continuous variables are presented as mean and standard deviation and the categorical variables as number and percentage. Pearson Chi-square test or Fisher's exact test was used to compare the categorical variables among Group E and Group L. Independent sample t-test was used to compare the continuous variables among the groups. Statistical analyses were conducted using SPSS Version 20.0 for Windows (IBM Corporation Armonk, NY, USA).

RESULTS

Forty patients were recruited in this study [Figure 1]. The participants in both groups were comparable with respect to age, height, weight, and distribution of gender and ASA PS classes [Table 1]. Group E showed significantly lower incidence of bucking (15% vs. 65%) and coughing (10% vs. 45%) compared to Group L. Incidence of breath holding, laryngospasm, desaturation, reintubation, regurgitation/aspiration, and vomiting did not show any significant difference in both groups [Table 2].

Table 1

Comparison of demographics and the American Society of Anesthesiologists physical status classes

Variables	Group E		Group L		P
	Mean	SD	Mean	SD
Age (years)	49.7	15.6	49.6	11.9	0.991
Weight (kg)	62.6	10.9	64.1	10.4	0.659
Height (cm)	158.0	11.0	157.0	8.6	0.750
Gender, n (%)
Male	14 (70)		17 (85)		0.451
Female	6 (30)		3 (15)
ASA PS I	10	50	9	45	0.752
ASA PS II-III	10	50	11	55

ASA=American Society of Anesthesiologists, PS=Physical status, SD=Standard deviation

Table 2

Comparison of variables at extubation and extubation quality score

Variables	Group E, n (%)	Group L, n (%)	P
Bucking
No	17 (85.0)	7 (35.0)	0.003
Yes	3 (15.0)	13 (65.0)
Coughing
No	18 (90.0)	11 (55.0)	0.031
Yes	2 (10.0)	9 (45.0)
Breath holding
No	19 (95.0)	18 (90.0)	1.000
Yes	1 (5.0)	2 (10.0)
Laryngospasm
No	19 (95.0)	19 (95.0)	1.000
Yes	1 (5.0)	1 (5.0)
Saturation <95%
No	18 (90.0)	19 (95.0)	1.000
Yes	2 (10.0)	1 (5.0)
Reintubation
No	20 (100.0)	20 (100.0)	NA
Yes	-	-
Aspiration
No	20 (100.0)	20 (100.0)	NA
Yes	0	0
Regurgitation/vomiting
No	19 (95.0)	18 (90.0)	1.000
Yes	1 (5.0)	2 (10.0)
Extubation quality score
Score 1-2	18 (90)	11 (55)	0.031
Score 3-5	2 (10)	9 (45)

In Group E, 90% of patients did not cough during extubation compared to 55% in Group L. The percentage distribution of extubation quality scores in both groups is depicted in Figure 2b. Comparison of extubation quality scores of 1–2 was significantly higher in Group E, but extubation quality score of 3–5 was significantly higher in Group L [P value 0.031, Table 2].

Extubation time was significantly shorter in Group E (4.0 ± 1.6 vs. 10.8 ± 1.6 min) compared to Group L. However, the recovery time was similar in both groups. Intraoperative fentanyl consumption was comparable in both groups. End-tidal isoflurane MAC was significantly higher in Group E (P < 0.001). Volume of blood from surgical drain at 24 h postoperatively was significantly lesser in Group L compared to Group E (27.5 ± 12.1 vs. 36.8 ± 11.8, P 0.019, Table 3). Heart rate and MAP values in both groups did not show any statistically significant difference during the study period [Table 4].

Table 3

Comparison of extubation and recovery times, postoperative bleeding, and anesthetic agents

Variables	Group E		Group L		P
	Mean	SD	Mean	SD
Extubation time (min)	4.0	1.6	10.8	1.6	<0.001
Recovery time (min)	10.4	1.4	10.8	1.6	0.384
Fentanyl consumption (µg)	153.5	29.8	156.5	30.0	0.753
End-tidal isoflurane MAC at extubation	0.5	0.2	0.0	0.0	<0.001
Bleeding from drain (mL)	27.5	12.1	36.8	11.8	0.019

SD=Standard deviation, MAC=Minimum alveolar concentration

Table 4

Comparison of heart rate and mean arterial pressures

	Group E		Group L		P
	Mean	SD	Mean	SD
HR at end of surgery	74.8	14.1	77.2	13.0	0.572
HR 1 min	86.3	15.2	82.2	13.3	0.370
HR 3 min	86.9	14.1	84.7	13.7	0.627
HR 5 min	84.0	16.1	86.3	13.5	0.635
HR 10 min	78.3	13.7	83.8	16.0	0.254
MAP at end of surgery	91.6	15.3	86.4	9.7	0.212
MAP 1 min	103.8	17.9	96.3	9.8	0.109
MAP 3 min	101.2	13.8	98.4	13.5	0.521
MAP 5 min	96.6	11.2	93.9	11.5	0.457
MAP 10 min	97.9	15.1	95.1	13.1	0.528

SD=Standard deviation, HR=Heart rate, MAP=Mean arterial pressure

DISCUSSION

In the present study, we found that extubation just before reversal of neuromuscular blockade resulted in lesser incidence of bucking, coughing, and bleeding into drain without affecting the recovery time. There were no added risks of aspiration, laryngospasm, or desaturation with this technique.

Bucking or coughing, often observed during extubation, following major neck surgeries can lead to high intrathoracic pressure, venous engorgement, and hematoma formation or increased bleeding into the drain.[1] Postoperative hematoma following thyroidectomy could be life threatening and has an incidence of approximately 4.2%.[4] Smooth extubation is important as intubation and extubation are aerosol-generating procedures and extubation is considered riskier than intubation.[5] The hemodynamic changes associated with these procedures are often due to catecholamine release leading to increase in heart rate and blood pressure, systemic vascular response, and myocardial contractility lasting up to 10 min.

Many methods are suggested for providing smooth extubation such as administration of drugs such as lignocaine or opioids,[6] but the use of these drugs may be associated with excessive postoperative sedation and depressed airway reflexes. Although lignocaine decreases severity of cough, breath holding and bronchospasm following extubation with minimal central nervous system depression, the associated blunted airway reflexes increase the risk of aspiration.[7] Agents such as dexmedetomidine and remifentanil have resulted in prolonged extubation times and are known to cause hypotension and bradycardia, slow the turnover of an operating room, and impact patient care.[8]

The usual concern with early extubation is risk of regurgitation and aspiration. This situation actually just mimics the period of induction to intubation but in a reverse manner. The risk of aspiration during induction to intubation is considered minimal in normal patients. Therefore, in patients without conditions predisposing to delayed gastric emptying, extubation just before reversal may not actually impart any significant additional risks. In the present study, we did not observe any incidence of regurgitation or aspiration in either group. Although applying cricoid pressure till patient is awake could reduce risk of aspiration further, we did not adopt it as we excluded patients at risk of aspiration.

Deep extubation is usually performed when patients are still in a deep anesthetized state after reversing muscle relaxants and when patients are generating adequate tidal volume and respiratory rate. It is associated with lesser incidence of coughing and desaturation but with higher risk of airway obstruction. Risks of laryngospasm and breath holding are comparable in both techniques.[910111213] We tried to overcome the risk of airway obstruction by placing a nasopharyngeal airway before extubation.

An alternative technique described is substituting laryngeal mask airway (LMA) for tracheal tube while patient is still anesthetized and paralyzed, followed by reversing neuromuscular blockade and extubation when awake. Exchange extubation with LMA has shown to decrease respiratory complications and hemodynamic stress responses.[1415] The problem with this technique is increased number of airway manipulation and therefore higher risk of aerosol generation.

We adopted a modified version of deep extubation in which reversal was administered immediately after extubation. Depth of anesthesia recommended to provide smooth extubation with this technique is usually higher, sevoflurane 1.5 MAC[16] or 1 MAC with additional dexmedetomidine or remifentanil.[17] We have tapered depth of volatile agents toward the end of surgery so that at end of skin suturing, it was approximately 0.5 MAC end-tidal isoflurane. We did not keep the patients very deep in the early extubation group since extubation was planned just before reversal.

The strong point of our study is that the technique described is very useful to provide a smooth extubation with reduced risk of aerosol generation as it effectively suppresses cough and bucking associated with traditional extubation. The major limitation of the study was that although we measured volume of blood in drain as a reflection of bleeding secondary to venous engorgement due to coughing and bucking or hemodynamic stimulation, many other factors such as age, male gender, malignant histology, extent of surgery, previous surgery, Graves' disease, and use of antithrombotic agents are also known to contribute to postoperative bleeding following thyroidectomy.[1819] Moreover, although the difference in volume of blood was significantly different as per statistical analysis, clinically the difference could not be considered significant. As postoperative hemodynamic parameters at extubation were comparable in both groups, increased intrathoracic pressures associated with coughing and bucking could possibly have caused more venous oozing at the surgical site.

Regurgitation and aspiration were assessed clinically only. Fiber optic bronchoscopic assessment would have been more valuable. The time of extubation was planned as for all regular extubations. The only difference from traditional extubation was that reversal was given just after extubation. Although an end-tidal 0.5 MAC isoflurane at time of extubation in early extubation group practically eliminated a paralyzed but awake stage, the use of bispectral index monitoring would have added more safety.

CONCLUSION

Extubation just before reversal of neuromuscular blockade resulted in lesser incidence of bucking and coughing during extubation with lesser postoperative bleeding compared to traditional technique of awake extubation without added risks of regurgitation, aspiration, or delayed recovery.

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Nil.

Conflicts of interest

There are no conflicts of interest.