Abstract

Intramuscular administration of ketamine as a premedication has been used for release of mentosternal contracture in cases of post burn mentosternal neck contractures. The present study was undertaken to find out the safety of the drug for the release of contractures. Patient were divided into five groups. The incidence of no. of attempts of difficult intubation and side effects of the drug were recorded during induction and perioperative period.

Introduction

Difficult endotracheal intubation is frequently, encountered in post burn contracture, a documented challenge for Anaesthesiologist. Direct laryngoscopy is hampered by presence of limited cervical hyperextension restricted mobility of the mandible, presence of scar tissue which obscure the anatomy of the laryngoscopy. The mandible becomes immobilized and is forced posteriorly, presence of microstomia may further distort the local anatomy. Most of the time difficulties of intubation are predicted and attempts of performing difficult intubations can be made in advance by keeping the difficult intubation drill ready. However, in patients with extreme deformity the functional and anatomical distortion may be such that all attempts to intubation may fail. Some times the nature of scar and functional abnormalities may be noted during routine preoperative assessment. On occasion therefore problems may arise during the induction of anaesthesia. This study describes our experience with safe and quick surgical release to facilitate endotracheal intubation in such cases.

Aims of the study

1. Maintenance of difficult airway
2. Preservation of Laryngeal/Pharyngeal Reflexes
3. Maintenance of haemodynamic stability
4. Quiet and calm patient

Method

This is a prospective study of 60 patients done in Plastic Surgery theatre, in the year 2003.

Patients were divided into 5 groups:

Group I had few fibrous bands on either side of the neck (Fig. 1).

Group II had few fibrous bands on both sides of the neck (Fig. 2).

In Group III chin is attached to sternum; some where between Mentosternal area (Fig. 3).

In Group IV chin is attached to sternum (Fig. 4).

In Group V microstomia with any one contractures of above grade (Fig. 5).

All patients had received Inj. Glycopyrolate, as a premedication. Patients were wheeled into the operation theatre.

Fig. 1 :Grade I : Few fibrous banks on one side of the neck	Fig. 2 :Grade II : Few fibrous bands on both sides of the nec

Monitors were attached (Cardioscope, pulse oximetry, capnography and Manual blood press), IV access was established. Accessories for difficult intubation kept ready. Group I/II patients had received routine General Anaesthesia after confirmation of ventilation with Inj. Pentothal Sodium + Scoline and long acting muscle relaxant.

Group III/IV were given Inj. Ketamine in

Fig. 3 :Grade III : Chin is attached to sternum somewhere between mentosternal area	Fig. 4 :Grade IV : Chin is attached to sternum	Fig. 5

the dose of 1 mg/kg IV. Contractures were released. After release of contractures, standard GA was given as above group. All patients were monitored for 24 hours for any complication.

Observations and Discussion

As per demographic data. Age group of our patients were between 10-40 years. Maximum number of patients were between 20-30 years and they were males. The number of females were more in 30-40 years of age group.

As per above graph in grade I no. of patients were 15, in grade II 10, in grade III 20 and in grade IV 15. Two patients of grade V were there.

This graph is showing the no. of attempts of intubation taken for intubating the patients of different grades.

In our study 13 patients got intubated in first attempt in group I; second attempt was needed in 2 patients. We could intubate 2 patients of Group II in 1st attempt and 8 patients in second attempt. In Grade III patients needed second attempt intubation in 8 patients and 12 patients needed third attempt intubation. Out of 15 patients of grade IV 13 patients needed third attempt and 2 patients could not be intubated. 2 patients of grade V which we have not included in our study we intubated in first attempt.

No complication was observed in Group I and Group II during perioperative period. In Group III and IV Inj. Ketamine was given. Out of 60 patients, two patients of Group IV had shown desaturation for which Laryngeal mask airway was introduced for supplementation of oxygen and maintenance of anaesthesia.

Prerequisites of anaesthesia are taken as aim of this study. Ketamine is the drug of choice which can fulfill all the prerequisites. The highest success rate is obtained when performed electively in awake and adult, well informed cooperative patient.

However, prediction is not always straightforward. While a number of techniques are available to the anaesthetist when intubation by direct laryngoscopy is impossible, the method of choice for each case depends on consideration of the functional abnormality. Blind nasal intubation may be successful, particularly when the base of the tongue is fixed anteriorly by the contracture process. However, positioning of the head and neck may be severely limited and repeated attempts risk nasal bleeding which may further endanger the airway. An illuminated introducer to guide tube placement has been advocated as a non traumatic, rapid technique.

Fibreoptic bronchoscopy as an aid to difficult endotracheal intubation has become established as the safest and most effective alternative to direct laryngoscopy and has been described in patients with post burn contracture of the neck.

However, many burn patients are extremely anxious at induction and lack of cooperation is common. Furthermore, bronchoscopy itself can be difficult if the anatomy of the airway is distorted due to soft tissue contracture, especially when repeated attempts to intubate have resulted in the presence of blood and secretions in the oropharynx.

The advent of the larynx mask has enabled procurement of a safe airway in several patients who could not be intubated by direct vision. However, placement may be hampered by the anatomical abnormalities described and airway maintenance may be jeopardized in operations which require turning the patient.

Contracture release of the neck prior to intubation was first described in 1964 by Tanzer et al. They suggested a release of the inferior half of the neck under local anaesthesia when difficulties are anticipated. Further release would follow successful intubation. The procedure has since been adopted elsewhere. Waymack et al described 17 emergency neck releases in 13 young patients. Failure to perform intubation following contracture release at four instances was resolved by emergency tracheostomy.

As stated above, a surgical neck release to enable intubation was initially only performed as an emergency procedure when unpredicted difficulty in intubation occurred. Anaesthesia, including muscle relaxation, had already been induced and the patient was requiring ventilatory support while repeated intubation attempts had failed. However, as confidence in the effectiveness of the release procedure has grown, surgical neck release has become a method of choice. Although several techniques are available, a quick incision release of the contracture is an important supplementary tool for the anaesthetist.

1. In an emergency, surgical release is a rapid and effective method to ensure maintenance of a clear airway and to facilitate successful intubation in the paralysed, anaesthetized patient.
2. An elective surgical release of neck contractures prior to intubation may be safely performed following induction in a lightly anaesthetized, spontaneously breathing patient directly after the first failed intubation attempt.

The surgeon should remain aware of the possibility of difficult intubation. He should be on hand to perform an emergency contracture release if necessary.

Those patients who have got operated for mentosternal contracture release in the past, could have similar problem during intubation for any other surgical procedure.

Conclusion

Intra venous Ketamine can be used safely in cases where we expect difficult intubation because of post burn mentosternal contractures.

Ketamine is an ideal drug as it fulfils the requirement of anaesthesia for such type of cases in the form of potent analgesia, sedation and maintenance of laryngeal and pharyngeal reflexes.

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*Associate Professor; **PG Student; Professor and Head of Anaesthesiology; Seth GS Medical College and KEM Hospital, Parel, Mumbai - 400 012.