Nicotine withdrawal and agitation in ventilated critically ill patients

Smoking is highly addictive, and nicotine abstinence is associated with withdrawal syndrome in hospitalized patients. In this study, we aimed to evaluate the impact of sudden nicotine abstinence on the development of agitation and delirium, and on morbidities and outcomes in critically ill patients who required respiratory support, either noninvasive ventilation or intubation, and mechanical ventilation.

We conducted a prospective, observational study in two intensive care units (ICUs). The 144 consecutive patients admitted to ICUs and requiring mechanical ventilation for >48 hours were included. Smoking status was assessed at ICU admission by using the Fagerström Test of Nicotine Dependence (FTND). Agitation, with the Sedation-Agitation Scale (SAS), and delirium, with the Intensive Care Delirium Screening Checklist (ICDSC), were tested twice daily during the ICU stay. Agitation and delirium were defined by SAS >4 and ICDSC >4, respectively. Nosocomial complications and outcomes were evaluated.

Smokers (n = 44) were younger and more frequently male and were more likely to have a history of alcoholism and to have septic shock as the reason for ICU admission than were nonsmokers. The incidence of agitation, but not delirium, increased significantly in the smoker group (64% versus 32%; P = 0.0005). Nicotine abstinence was associated with higher incidences of self-removal of tubes and catheters, and with more interventions, including the need for supplemental sedatives, analgesics, neuroleptics, and physical restraints. Sedation-free days, ventilator-free days, length of stay, and mortality in ICUs did not differ between groups. Multivariate analysis identified active smoking (OR, 3.13; 95% CI, 1.45-6.74; P = 0.003) as an independent risk factor for agitation. Based on a subgroup of 56 patients, analysis of 28 pairs of patients (smokers and nonsmokers in a 1:1 ratio) matched for age, gender, and alcoholism status found similar results regarding the role of nicotine withdrawal in increasing the risk of agitation during an ICU stay.

Nicotine withdrawal was associated with agitation and higher morbidities in critically ill patients. These results suggest the need to look specifically at those patients with tobacco dependency by using the FTND in ICU settings. Identifying patients at risk of behavioral disorders may lead to earlier interventions in routine clinical practice.