12 Intensive care

Abstract

From the start of the HIV epidemic, respiratory failure has been the most common indication for patients with HIV infection to be admitted to the intensive care unit (ICU). In the era of highly active antiretroviral therapy (HAART), Pneumocystis jirovecii pneumonia (PCP), bacterial pneumonia and tuberculosis continue to be significant causes of respiratory failure; however, admission to the ICU with non-HIV-associated respiratory causes, including emphysema and asthma, is increasingly encountered [1–3]. An emerging cause of respiratory failure requiring admission to the ICU is immune reconstitution inflammatory syndrome (IRIS) [4]. Non-respiratory causes, including renal and hepatic failure, cardiac disease, drug overdose and severe toxicity from HIV therapy are increasingly recognised [1–4]. Early in the HIV epidemic, HIV-seropositive patients with critical illnesses were deemed incurable. ICU mortality rates were high and long-term survival rates were low [5–7]. The majority of admissions to the ICU were patients with severe PCP. As a direct result of HAART, there has been a sustained reduction in HIV-associated morbidity and mortality. Several studies report improved outcomes for HIV-seropositive patients requiring admission to the ICU in the HAART era [1–3,8,9]. One recent study suggests that outcomes from ICU admission for HIV-seropositive patients are equivalent to those for the general medical (non-HIV-infected) population [3]. HIV-seropositive patients should not be refused ICU admission based merely on the patient's HIV-serostatus (category IV recommendation). Improved survival from HIV-associated PCP after 1996 has been shown to be independent of the use of HAART and likely reflect general improvements in the ICU management of acute lung injury (ALI) [10]. All HIV-seropositive patients with ALI/acute respiratory distress syndrome (ARDS) who are mechanically ventilated should be managed using the same protocols for management of ALI/ARDS as among general populations – with low tidal volumes and controlled plateau pressures, for example using the ARDS Network guidelines [11] (category IV recommendation). It is currently unclear whether starting HAART on the ICU confers improved outcome for HIV-seropositive patients admitted to the ICU [1,3,10]. In such patients, the short-term effect of HIV RNA level and CD4 cell count on mortality is unclear. Among HIV-seropositive patients already in receipt of HAART, there was no apparent improvement in survival when compared with HIV-seropositive patients not taking HAART [3]. The use of HAART in severely unwell HIV-seropositive patients is confounded by several issues, including drug absorption, requirements for dose modification in the presence of intercurrent renal- and hepatic-induced disease, drug–drug interactions (see Table 12.1), HAART-associated toxicity and IRIS. In some circumstances it may be more appropriate to change HIV therapy rather than dose modify. Advice should be sought from an HIV clinician and/or pharmacist prior to planned modification of HAART. Expert daily consultation between HIV and ICU physicians is essential in the management of critically-ill HIV-seropositive patients admitted to the ICU. Additionally, the advice of a pharmacist with expertise of treatment of HIV-associated infection should be sought. In some cases this expertise will be obtained by transfer of the patient to a tertiary centre (category IV recommendation).