Radiation induced changes in the airway—anaesthetic implications

Abstract

medication was with oral diazepam 10mg the previous night and 5mg the next day. Oral ranitidine 150mg and oral metoclopramide 10mg were given in the morning on day of surgery. One percent xylometazoline drops were instilled in both nostrils. Since the patient had no history of airway compromise during sleep or in the supine position, intramuscular morphine 4.5mg and promet-hazine 12.5mg were given along with glycopyrollate 0.2mg, 45 minutes before induction. Topical airway anaesthesia was accomplished by nebulisation with 2ml of 2% lignocaine, lignocaine viscus (2%) gargle 6ml, transtracheal injection of 2 ml, 4% xylocaine and 4-5 drops of 4% xylocaine instilled nasally. With A 65 year old, 47 kg male, diagnosed to have carcinoma of the buccal mucosa, was scheduled for wide full thickness excision of the tumour, functional neck dissection and pectoralis major myocutaneous flap reconstruction for lining the oral cavity. When the patient presented to our preanaesthetic clinic for evaluation, he gave a history of having had radiotherapy for carcinoma of the lip, detected 7 years previously. He had received 5000-cgy radiation as 16 fractions over 4 weeks. Six months later, he noticed progressive recession of his lower jaw. He did not have any respiratory symptoms suggestive of obstruction or a history of snoring. His physical examination revealed normal vital signs, stable cardiovascular and respiratory systems. Airway examination revealed the following: (i) receding chin area (ii) mouth opening of 3cm (iii) edentulous (iv) modified Mallampati classification of III (v) normal atlanto-occipital joint extension (vi) an exophytic mass in the oral cavity 3 x 3cms arising from buccal mucosa on the right, extending to the adjacent floor of mouth, 1.5cm behind the oral commissure. The growth was fleshy, fri-able and bled on touch, and thyromental distance and anterior mandibular length could not be assessed, as the mandible was absent. His haematological, biochemical investigations as well as chest X-ray and electrocardiogram were normal. Lateral view X-rays of the mandibular area revealed a small 2cm shadow on the left side suggestive of calcified periosteum (Figure 1). Summary: Radiation induces a variety of changes in the airway that can potentially lead to difficult intubation. Osteoradionecrosis (ORN) of the mandible, a severe consequence of radiotherapy for head and neck malignancies can cause a reduction of the 'mandibu-lar space' and alteration of the morphometric measurements, viz. thyromental distance, hyomandibular distance, anterior mandibular length and posterior mandibular length, that usually predict difficult intubation. A case of osteoradionecrosis of the mandible presenting for elective surgery under general anaesthesia is presented. The primary intention of this article is to focus awareness amongst anaesthesiologists on the myriad of airway problems to be anticipated in cancer patients who present for surgery after radiotherapy.