Comparing the Ease of Mask Ventilation, Laryngoscopy, and Intubation in Supine and Lateral Position in Infants with Meningomyelocele.

BACKGROUND: The biggest anesthetic challenge in infants with thoracolumbar /sacral meningomyelocele is securing the airway. For securing the airway, most of the anesthesiologist's practices supine position with doughnut or head ring placed around the swelling to prevent rupture, which has got disadvantages like risk of rupture, infection and damage to neural structure. Left lateral position has been recommended previously for tracheal intubation in post-tonsillectomy hemorrhage. Several studies have shown successful ventilation in lateral position using laryngeal mask airway and intubation using video laryngoscopes. AIMS AND
OBJECTIVES: Primary objective is to compare the time taken for intubation, number of attempts required for intubation. Secondary objective is to compare ease of mask ventilation, Cormack Lehane grading and Backwards Upward Rightwards Pressure [BURP] manoeuvre.
MATERIALS AND METHODS: A comparative, prospective randomized, controlled trial of 60 infants undergoing thoracolumbar/sacral meningomylocele repair. Infants were allocated to one of two groups of 30 patients each, by computer-generated randomization into Group S: mask ventilation, laryngoscopy and intubation in supine position and Group L: mask ventilation, laryngoscopy and intubation in lateral position. STATISTICAL METHODS: Chi-square/Fisher Exact test was used to find the significance of study parameters on categorical scale between two or more groups.
RESULTS: Mean intubation time of sixteen seconds were clinically acceptable and comparable in each of the two positions P = 0.145. Ten patients in the left lateral position, eight patients in the supine position required second intubation attempts before the airway was secured. Only 8.3% of our patients required third intubation attempts.
CONCLUSION: Anesthesiologist should pay more attention to the safety and quality of mask ventilation, laryngoscopy and intubation in meningomylocele infants. Both supine and lateral position were comparable.

INTRODUCTION

Supine position is the conventional position used for tracheal intubation in both adults and children. The left lateral position has been recommended previously for tracheal intubation in the posttonsillectomy hemorrhage.[1] Meningomyelocele is a complex congenital spinal anomaly, resulting from neural tube defect presenting for surgery during the first 4 weeks of gestation. Early surgery recommended to avoid the risk of infection and to prevent further damage to nervous tissue.[2] Anesthetic challenges in meningomyelocele include securing airway with proper positioning of the child during intubation to avoid rupture of swelling and cerebrospinal fluid (CSF) leak, intraoperative prone positioning and its associated complications, and accurate assessment of blood loss. Anesthesia for meningomyelocele always poses a challenge to anesthesiologist as one has to deal with neonates and infants who already have so many anatomical and physiological differences compare to the adults or normal children.[23] The effect of positioning in neonates for induction of general anesthesia must also be considered. No direct pressure should be applied to the exposed neural placode. Various methods are described in the literature, i.e., intubation in the supine position with doughnut or head ring placed around the swelling to prevent rupture[4] as the supine position is more familiar for induction. The advantages of lateral position are, it increases functional residual capacity, widens the upper airway of a sedated spontaneously child, decreases upper airway obstruction, prevents the laryngeal structures from collapsing, and gravity also aids laryngoscopy in the left lateral position. Lateral intubation in pediatric patients is a useful technique in certain cases, including during management of meningomylocele, as it avoids the rupture of swelling, CSF leak, infections, and related morbidity. In this study, our primary aim was to compare the time taken for intubation and number of attempts required for intubation. The secondary aim is to compare ease of mask ventilation, Cormack–Lehane gradings, and Backward Upward Rightward Pressure (BURP) in lateral and supine position in infants undergoing meningomyelocele surgery under general anesthesia.

METHODOLOGY

This study was approved by the Institutional Ethical Committee. Written informed consent was obtained from the parents of infants before the surgery. Sixty infant patients with the American Society of Anesthesiologists physical status I and II, scheduled for lumbar/sacral meningomyelocele surgeries, from December 2016 to August 2018 were included in this study. The patients with known or predicted difficult airway, cardiovascular diseases, drug allergy, and coagulation disorders, or those whose parents did not give consent were excluded from the study. Once the patient was in the operating room, the standard monitors, including pulse oximetry, electrocardiogram, and noninvasive blood pressure were attached.

Based on the results on pilot study and meeting the specifications of statistical power 80% and significance, the sample size of 60 is considered for this study. The patients were randomly assigned (using a random number generator) to one of two groups:

Group S: Mask ventilation, direct laryngoscopy, and endotracheal intubation in the supine position.

Group L: Mask ventilation, direct laryngoscopy, and endotracheal intubation in the lateral position.

Before induction, patients in Group L were placed in the left lateral position. The height of the table was adjusted and hence that the top of the patient's head was at the chest level in the lateral group and xiphisternum of the anesthesiologist in the supine group. All patients were preoxygenated with 6 L of oxygen for 3 min using Jackson-Rees anesthesia circuit. Anesthesia was induced with fentanyl 2 μg/kg IV followed by thiopentone 5–7 mg/dl IV. The ability to mask ventilate was checked, and if found satisfactory, neuromuscular blockade was achieved with atracurium 0.5 mg/dl. All patients were ventilated in the supine and lateral position for 3 min. The ease of mask ventilation was then assessed as follows:

Easy: Adequate ventilation possible by one person and no increase in fresh gas flow (FGF) or use of oral airway required

Difficult but adequate: Adequate ventilation possible but needs two people and an increase in FGF or use of oral airway

Inadequate: If mask ventilation was inadequate in spite of the above measures in the supine/lateral position.

After adequate neuromuscular blockade was ensured, a senior anesthesiologist (>5 years’ experience in anesthesia) performed direct laryngoscopy using Miller blade (straight blade) to grade the degree of laryngeal visualization as per the modified Cormack–Lehane classification, initially without and then with BURP maneuver. Appropriate size of uncuffed endotracheal tube was placed. Time for intubation (defined as the time from picking up the laryngoscope to confirmation of tracheal intubation by capnography) in both supine and lateral position noted. The primary aim of this study is to compare the time taken for intubation and number of attempts at laryngoscopy and intubation. The secondary aim is to compare ease of mask ventilation, Cormack–Lehane gradings, and BURP. Others findings such as mucosal injury, use of stylet, esophageal intubation, and desaturation were also noted. When >1 intubation in attempts was required, time from picking up the laryngoscope for the first intubation attempt until confirmation of successful intubation by capnography was considered to be the total intubation time. Patients with anticipated airway difficulties were excluded from this study. All mask ventilation, laryngoscopy, and intubations were performed by a single investigator, who had considerable experience with the lateral intubation in infants.

The statistical software, namely, Statistical Package for Social Sciences (SPSS version 15.0 IBM Corp., Armonk, NY) and R environment version 3.2.2 (R is a implementation of the S programming language. S was created by John Chambers in 1976 at Bell labs. R was created by Ross Ihaka and Robert Gentleman at the university of Auckland, New Zealand, and is currently developed by R Development core team) were used for the analysis of the data, and Microsoft Word and Excel were used to generate graphs and tables. The level for all analyses was set at P = 0.05. Fisher's exact test was used to compare the time required for intubation, number of attempts at intubation, ease of mask ventilation, Cormack–Lehane gradings, and BURP.

RESULTS

The two groups were comparable in terms of the demographic data such as age, weight, height, and sex. Time taken for intubation in the supine group was 15.73 ± 8.43 s, whereas in the lateral group was 15.96 ± 6.47 s, (P = 0.145). Eighteen patients in Group S (60%) were intubated by a single attempt compared to nineteen of them in Group L (63.3%). Eight patients in Group S (26.7%) required two attempts compared to ten in Group L (33.3%), whereas three attempts were required in four patients in Group S (13.3%) and one in Group L (3.3%), and this difference was not statistically significant (P = 0.451) [Figure 1]. Overall intubation success rates were 100% for both the groups.

Figure 1

Number of attempts. P = 0.451, not significant, Fisher's exact test

Mask ventilation was found to be easy in 90% of infants in Group S and 80% in Group L, except three patients in the supine group (10%) and six patients in the lateral group (20%) where oral airway was used (P = 0.472). In the lateral group, no infants mask ventilation was totally inadequate requiring change over to supine position. No infants in both groups required either increase in FGF or requirement of two persons for mask holding and ventilation [Table 1].

Table 1

Use of airway during mask ventilation

Use of airway during mask ventilation	Group L (%)	Group S (%)	Total (%)
No	24 (80)	27 (90)	51 (85)
Yes	6 (20)	3 (10)	9 (15)
Total	30 (100)	30 (100)	60 (100)

P=0.278, Not significant, Fisher’s exact test

When the laryngoscopic view was compared in supine without the application of BURP, all patients had a laryngoscopic grading of 1 (n = 9, 30%), 2a (n = 12, 40%), 2b (n = 5, 16.7%), and 3 (n = 4, 13.3%). Laryngoscopic view in lateral position without the application of BURP was 1 (n = 14, 46%), 2a (n = 12, 40%), 2b (n = 2, 6.7%), and 3 (n = 2, 6.7%), (P = 0.405). There was no Grade 4 view in both groups [Table 2].

Table 2

Cormack-Lehane grade during laryngoscopy distribution in two groups of patients studied

Cormack-Lehane grade during laryngoscopy	Group L (%)	Group S (%)	Total (%)
Full view of the vocal cords	14 (46.7)	9 (30)	23 (38.3)
Partial view of the vocal cords	12 (40)	12 (40)	24 (40)
Only arytenoids and epiglottis seen	2 (6.7)	5 (16.7)	7 (11.7)
Only epiglottis seen	2 (6.7)	4 (13.3)	6 (10)
Total	30 (100)	30 (100)	60 (100)

P=0.405, Not significant, Fisher’s exact test

The supine position resulted in optimal view (Grade 1 and Grade 2a) in 46.7% of patients and improvement with application of BURP in 53.3%, whereas in the left lateral position resulted in 66.7% of patients and improvement with application of BURP in 33.3%, P = 0.118 [Figure 2 and Table 3].

Figure 2

External laryngeal manipulation during intubation. P = 0.118, not significant, Chi-square test

Table 3

Backwards Upward Rightwards Pressure

External laryngeal manipulation during intubation	Group L (%)	Group S (%)	Total (%)
No	20 (66.7)	14 (46.7)	34 (56.7)
BURP	10 (33.3)	16 (53.3)	26 (43.3)
Total	30 (100)	30 (100)	60 (100)

P=0.118, Not significant, Chi-square test. BURP=Backward Upward Rightward Pressure

Stylet was used for intubation in two infants in Group S and one infant in Group L. Esophageal intubation was observed only in five infants in Group S compared to three infants in Group L, total 13.3% [Table 4]. No desaturation <95%, as measured by pulse oximetry were observed in either group, mucosal injury not observed in any patients.

Table 4

Esophageal intubation distribution in two groups of patients studied

Esophageal intubation	Group L (%)	Group S (%)	Total (%)
No	27 (90)	25 (83.3)	52 (86.7)
Yes	3 (10)	5 (16.7)	8 (13.3)
Total	30 (100)	30 (100)	60 (100)

P=0.706, Not significant, Fisher’s exact test

DISCUSSION

Meningomyelocele is hernia protrusion of meninges plus neural tissue resulting from congenital failure of the neural tube to close. The majority of meningomyelocele defect (80%) occur in the lumbosacral area and neurological deficits distal to the defect are more severe.[45] The clinical presentation will vary significantly according to the anatomical defect involved. These babies present a potential risk of rupture of sac during induction and intubation, care should be taken to avoid rupture of swelling and CSF leak, either in the lateral decubitus position or more commonly supine, with a ring-shaped sponge to support and relieve pressure from the herniation. Previous studies have shown tracheal intubation in lateral position can be difficult in adults.[6] Several studies have shown successful ventilation in lateral position with the laryngeal mask airway[7] intubation using video laryngoscopes.[8] We choose to study left lateral position for ventilation and intubation, as right lateral position is relatively difficult and attributable to the positioning of the tongue, which (influenced by gravity) ends to slip off the laryngoscope blade while the blade is inserted from the right side of the tongue.[9]

Lateral position leads to an increase in functional residual capacity[10] and it is considered superior in ensuring a clear airway in anesthetized or sedated spontaneously breathing children.[11] This position widens the upper airway of a sedated spontaneously breathing healthy child and decreases upper airway obstruction.[12] Intubation in the lateral position is desirable in several conditions such as large cervical or thoracic meningomyelocele or cystic hygroma and abscesses. Gravity also aids laryngoscopy in the left lateral position. The lateral position also decreases upper airway obstruction in anesthetized adults and children with sleep apnea;[13] and also prevents the laryngeal structures from collapsing.[14]

We compared ease of mask ventilation, laryngoscopy, and tracheal intubation of infants in the lateral and supine position undergoing meningocele repair. Overall intubation success rates were similar in each position: mean intubation times of 16 s were clinically acceptable and comparable in each of the two positions. Intubation with direct laryngoscopy in the left lateral position has been studied by McCaul et al.[15] who report a success rate of 79% with a mean intubation time of 39 s. Their criteria for failed intubation were duration more than 60 s or 2 attempts. Only 8.3% of our patients required third attempts at intubation, and no patients required more than 60 s before the airway was secured; furthermore, our mean intubation time was 23 s shorter than that by McCaul et al. Nearly 33.3% in the left lateral position and 26.7% in the supine position required second intubation attempts before the airway was secured.

Sorake et al. found mask ventilation to be difficult in 8.3% of patients in the lateral group but adequate by either requirement of two persons, insertion of oral airway or increase in FGF, without the need to change to supine.[16] Whereas in this study, 10% of patients in Group S and 20% of patients in Group L, it was found to be difficult but adequate by the insertion of oral airway. In Group L, no patients required changeover to the supine position.

Laryngoscopic airway examination was performed in anesthetized patients, in the supine and left lateral position, and in the presence and absence of BURP. The left lateral position resulted in optimal view, i.e., Cormack–Lehane Grade I and Grade 2a in 66.7% of patients and improvement with the application of BURP in 33.3%, whereas supine position resulted in 46.7% of patients and improvement with the application of BURP in 53.3%. BURP maneuver is widely accepted as an aid to improve the visualization during laryngoscopy.[1617] Takahata et al.[18] studied effects of BURP maneuver on direct laryngoscopy. They compared the visualization of the larynx using the BURP maneuver with that of laryngoscopy with and without simple laryngeal pressure (back). BURP did not have any effect on intubation time.

Although the difference in glottis view between the two positions was not statistically significant, clinically, there was optimal view in the left lateral position as the Miller straight blade directly lift epiglottis. Patients with anticipated airway difficulties were excluded from this study; this explains why the modified Cormack–Lehane Grade 4 scores were not encountered in any of the two intubation positions.

Esophageal intubation occurred in three of patients in the left lateral positions and five in the supine position (total 13.3%) and no patients desaturated before the airway were secured. Stylet was used in one patient in the lateral group and two in the supine group to aid in intubation.

The overall intubation success rates were very high, and the time required for intubation was similar in both positions, supine and lateral. Thus, the lateral position might be practiced for mask ventilation, laryngoscopy, and intubation in infants undergoing meningomyelocele surgery as it can overcome position related complications which is associated with the supine position. Limitation of this study is that we included only low predictive infants with difficult airway and also we had a single “experienced” intubator do all the intubations. Infants with a difficult airway, including hydrocephalus and syndromic features, were excluded from the study.

CONCLUSION

Tracheal intubation is one of the most critical situations for airway management. The anesthesiologist should pay more attention to the safety and quality of intubation in the pediatric age group with meningomyelocele. Both supine and lateral positions were comparable. Intubation in lateral position is a simple and rapid method for patients with normal airway, and it is a safe alternative to supine intubation in meningomyelocele infant.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.