December 1992, Volume 42, Issue 12

Case Reports

VOCAL CORD PARALYSIS FOLLOWING ENDOTRACHEAL INTUBATION

Sajjad Akhtar  ( Medical Students Class of 93 and 91, The Aga Khan University Medical College, Karachi. )
Jameel Hyder  ( Department of Ear, Nose, The Aga Khan University Medical College, Karachi. )
Tanveer Janjua  ( Medical Students Class of 93 and 91, The Aga Khan University Medical College, Karachi. )

INTRODUCTION

Endotracheal intubation has many complications. We describe a case of bilateral vocal cord paralysis following endotracheal intubation which is rare but a known complication. The possible factors contributing to this complication and measures which can be taken to prevent it have also been discussed.

CASE REPORT

A 60 year old lady presented to the emergency room with 2 days history of abdominal distention, colicky pain and constipation. Her chest x-ray showed pneumo­peritoneum. She underwent exploratory laparotomy the same day. She was found to have a tumour of the sigmoid colon alongwith caecal perforation. A subtotal colonic resection with ileocolic anastomosis was performed. Her preoperative assessment was ASA III and she was intubated with a red rubber tube with an 8mm cuff It was intubation grade I. The cuff was inflated with room air. During the procedure 02 was kept at 1.5 L/min and N2O2L/min. The procedure took 3 hours after which she was extubated. Her post-anaesthetic recovery was un­remarkable. ­On 2nd postoperation day the patient developed inspiratory stridor. She also became agitated and breath­less. The following day she was referred to the ENT department. On fibreoptic laryngoscopy examination both vocal cords were in the paramedian position with slight mobility. She was put under strict observation to evaluate for a possible tracheostomy but on 4th pos­toperation day her condition started to improve progres­sively and on the 8th postoperation day another fibreop­tic laryngoscopy showed complete left vocal cord paralysis while the right vocal cord had normal mobility. Patient was discharged and repeat fibreoptic laryngos­copy two weeks later found both vocal cords to be mobile and normal.

DISCUSSION

Complications resulting from endotracheal intuba­tion have been well reviewed1. Fortunately, serious problems are rare but a great many people after intuba­lion complain of pain in the throat. Hoarseness, which is a less common problem can occur due to nodules, granulomas and other consequences of the injury to the mucosae. But sometimes hoarseness is due to paralysis of the vocal cords which if bilateral can even cause stridor and respiratory obstruction2. Kambic and Radsel3 examined 1000 people after extubation and detected severe lesions of larynx in 62 patients but they did not mention vocal cord paralysis due to recurrent laryngeal nerve palsy. Searching pub­lished work Cavo4 in 1985 found 36 cases which were clearly the outcome of endotracheal intubation. Follow­ing this there have been a few reports of this complication in literature5,6. Most of these cases when followed recovered in days to months. The inference that many of these cases were avoidable led to the study of the anatomy of the recurrent laryngeal nerve and pressure within the en­dotracheal cuff during anaesthesia. Ellis and Palister7 after tracing the recurrent laryngeal nerve in the larynx described its two branches. An anterior and a posterior one. They proposed that itwas the anterior branch which was compressed between the cuff of the endotracheal tube and the lamina of the thyroid cartilage. Cavo\\\'s4 dissection of recurrent laryngeal nerve largely confirmed its anatomy. He found that the anterior branch of the nerve, as it ascends on the medial side of the rim of the thyroid cartilage, comes to lie on the top of the lateral cricothyroid muscle. At this level it lies close to the mucosal surface beneath the body of arytenoid about 6-10 mm below the end of true vocal cord. Here it is vulnerable to compression between an expanded cuff and the overlying thyroid cartilage. The pressure changes occurring in the endotracheal cuff while the subject is under anaesthesia have also been analysed8. It has been found that a diffusion of gas occurs across the semiper­meable membrane of the endotracheal tube; nitrous oxide particularly has been found to diffuse rapidly across the membrane from an area of high concentration to an area of relatively low concentration thus causing an increase in the cuff pressure after some time. In our case also the endotracheal cuff was inflated with (room) air which might have resulted in diffusion of N2O into the tube and thus increasing endotracheal cuff pressure resulting in pressure neuropraxia of the anterior branch of the recurrent laryngeal nerve and bilateral vocal cord paralysis. As in our case nearly all patients with this rare complication recover spon­taneously, usually within six months9. The incidence of vocal cord paralysis might be reduced almost to nil if anaesthetists make a routine of marking endotracheal tubes 1.5 cm above the upper level ot the cull to tacilitate accurate placement below the susceptible area and to use nitrous oxide or normal saline to inflate the cuff and periodic evacuation and reinflation of the cuff4-10.

ACKNOWLEDGEMENTS

We are thankful to Mr. Majid Jalil, Mr. Asif Ehalid and Dr. Aqeel for their help in preparing this report.

REFERENCES

1. Blanc, V.P. and Tremblay, N.A.G. The complications of tracheal intubation; a new classification with a review of literature. Aneath. Analg., 1974;53:202-13.
2. Kambic, V. and Radsel, Z. Intubation lesions of the larynx, Sri. Anacath., 1978;50:87­-90.
3. Cavo, J.W. Jr. True vocal cord paralysis following intubation. Larangoscope, 1985;95:1352-59.
4. Lim, E.K., Chia, KS. and big. BK. Recurrent laryngeal nerve palsy following endorracheal intubation. Anaesth. lnrensive Care, 1987;15:342-45.
5. Ellis, PD. and Pallister, W.K. Recurrent laryngeal nerve palsy and endotracheal intubarion. 3. L.aryngol. Owl, 1975;89:823-26.
6. Stanley, T.Fl., Kawamura, R. and Graves, C Effect of nitrous oxide on volume and pressure ofendotracheal tubecuffs. Anasthesiology, 1974;41:256-62.
7. Questions and Answers. JAMA., 1982; 247:2036-37.
8. Laryngeal paralysisafter endotracheal intubation (editorial). Lancer, 1986;1:536-37.

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