An adult non-obese male, a case of obstructive sleep apnoea posted for tonsillectomy and septoplasty - challenges faced
A 30-year-old male patient with history suggestive of OSA was posted for tonsillectomy and septoplasty under general anaesthesia. He had history of recurrent attacks of rhinitis on and off over a year. Besides, he gave history of snoring severe enough to disturb the person next door, episodes of airway obstruction, probable hypopnoea during sleep and daytime somnolence. He was thus investigated and polysomnography done. The study showed minimum SpO2 values of 51% lasting up to 10 seconds, seven episodes of SpO2 <88%, total snoring episodes of 205 and mean duration of snoring episodes of 6 seconds. The average minimum O2 saturation was 83.9%, maximum heart rate 141/min with an average of 96.4/min and desaturation index of 81.1. The AHI (Apnoea hypopnoea index) was significantly high at 80.0/hour. He had enlarged tonsils and left deviated nasal septum. On admission, a thorough preoperative evaluation was done. General and systemic examination did not suggest any gross abnormality. The blood pressure was 130/80 mmHg. The calculated BMI (body mass index) was 26.1 kg/m2 and neck circumference 41cm. He had a high arched palate, large tongue [] and an MPC (Mallampati classification) grading of 3. The thyromental distance was 6cm and sternomental distance was 11.7 cm. The routine investigations including the PCV (Packed cell volume), ECG (Electrocardiogram), CXR (Chest X-ray), thyroid function and coagulation studies were normal. After a thorough preoperative assessment, confirmation of NBM (Nil by mouth) status and written informed consent, the patient was taken up for tonsillectomy under general anaesthesia. He was premedicated with inj. atropine 0.6mg IM and inj. diclofenac sodium 75 mg IM half an hour prior to surgery. After securing the intravenous line, inj. ranitidine 50mg. and inj. ondensetron 4 mg were given. The patient was preoxygenated with 100% oxygen for five minutes and induced with gradually increasing concentration of sevoflurane up to 8% with 100% oxygen. Obstruction during mask ventilation was noted and an oral airway was thus inserted. After good jaw relaxation, decrease in muscle tone and depth of respiration, laryngoscopy was attempted. Laryngoscope was difficult to negotiate due to large tongue and only the epiglottis was visualised (Cormack and Lehane grade III), suggesting difficult intubation. Blind nasal intubation was done using a no. 7.5 cuffed endotracheal tube. The tube was secured and throat pack inserted. Maintenance of anaesthesia was done using o2, sevoflurane and vecuronium as muscle relaxant. Enlarged tonsils were removed. After achieving haemostasis, checking adequacy of reflexes, tone, power and awake status, extubation was done after thorough suctioning under vision and pack removal. Inj. paracetamol 1gm IV was given postoperatively every 6 hourly over 24 hours. Intraoperatively, pulse rate, non-invasive blood pressure, SpO2 (oxygen saturation) and EtCO2 (end tidal carbon dioxide) were monitored. Postoperatively, the patient was kept in right lateral position with oxygen by ventimask and nasopharyngeal airway in situ.\nWe monitored the pulse rate, blood pressure and oxygen saturation throughout the first postoperative night, off O2 mask. Clinically, we found that the number of hypoapnoeic episodes had dropped, the minimum drop in O2 saturation was 80% and the daytime somnolence was considerably lower the next day.\nSeptoplasty was deferred for the present as it would involve plastering the nose and further jeopardize respiration.