Age and comorbidity as risk factors for vocal cord paralysis associated with tracheal intubation

Background. Vocal cord paralysis after tracheal intubation may be attributed to ageing and comorbidity. However, the relationship between patient characteristics and the risk of vocal cord paralysis is unknown. Methods. We prospectively analysed data representing 31 241 consecutive surgery patients who underwent tracheal intubation to determine whether duration of intubation, age, sex, and cardiovascular, cerebrovascular, and metabolic diseases were risk factors for vocal cord paralysis associated with intubation. Patients with vocal cord paralysis from any other causes were excluded. Results. Twenty-four (0.077%) suffered vocal cord paralysis (left, 16 patients; right, 8 patients). The risk was increased when intubation lasted 3-6 h (odds ratio, 2.0; 95% confidence interval, 1.1-5.6; P=0.002) or 6h or more (odds ratio, 14.5; 95% confidence interval, 5.2-40.9; P<0.0001). The risk was increased in patients aged 50-69 (odds ratio, 3.6; 95% confidence interval, 1.2-11.1; P=0.02) and 70 yr or above (odds ratio, 3.9; 95% confidence interval, 1.2-12.8; P=0.02). The risk was increased with diabetes mellitus (odds ratio, 2.5; 95% confidence interval, 1.1-7.3; P=0.03) and hypertension (odds ratio, 2.1; 95% confidence interval, 1.1-6.0; P=0.03). Conclusions. The risk of vocal cord paralysis was increased three-fold in patients aged 50 or above, two-fold in patients intubated 3-6 h, 15-fold in patients intubated 6 h or more, and two-fold in patients with a history of diabetes mellitus or hypertension. Our results are informative for informed consent, patient counselling, and intubation decision-making.