(p. 193) Antidepressants in critical illness 

Selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), and atypical antidepressants are considered first-line agents for depression in the intensive care unit (ICU) setting, and are preferred over older antidepressants due to their more benign side effect profile and tolerability. This chapter reviews the literature on the use of antidepressants in the ICU. Common side effects of SSRIs include insomnia and gastrointestinal discomfort, while citalopram may uniquely cause prolongation of the QTc interval. All SSRIs carry a risk for the development of serotonin syndrome following overdose. SNRIs are similar to SSRIs in their side effect profile, although they are more likely to cause hypertension. Mirtazapine is strongly associated with sedation and weight gain. Stimulants may also be used to treat depression in the medically ill, and can be particularly effective in treating apathy, low energy, and loss of appetite. Monotherapy is typically the initial treatment strategy and low doses are generally recommended in the ICU setting. Efficacy may not be apparent for up to 8 weeks. Patients who have been taking an antidepressant prior to their arrival in the ICU should continue on the medication so as to prevent discontinuation syndrome. Delirium may warrant cessation of the antidepressant and potentially dangerous medication interactions also need to be evaluated. At present, there is no evidence to suggest that an antidepressant should be initiated after a significant physical or emotional trauma.