Researchers found higher rates of post-intubation hypotension (PIH) among critically ill patients who were immunocompromised compared with those who were not.
The study, presented at the Society of Critical Care Medicine’s 2017 Critical Care Congress (abstract 1031), found that significant predictors of PIH were advanced age, higher illness severity, pre-intubation hemodynamic instability and prior use of noninvasive ventilation. In addition, mortality was higher among immunocompromised PIH patients in the ICU and the hospital in general, according to the researchers from Mayo Clinic in Rochester, Minn.
The study, which included 269 critically ill adult patients, defined immunocompromised as patients with any solid-organ or non–solid-organ malignancy or transplant requiring chemotherapy. The study defined PIH as a decrease in systolic blood pressure to less than 90 mm Hg, or a decrease in mean arterial pressure to less than 65 mm Hg, or the initiation of any vasopressor medication. The study then stratified patients based on development of PIH.
PIH Receiving More Attention
PIH occurred in 141 (52%) of the patients. Patients who developed PIH were more likely to be older (56.35±10.91 years vs. 53.30±11.83 years; P=0.03), have higher Acute Physiology And Chronic Health Evaluation III scores (111.75±29.56 vs. 94.45±27.38; P≤0.01), have an elevated shock index (SI; 1.00±0.29 vs. 0.84±0.25; P≤0.01) and a modified shock index (MSI; 1.43±0.42 vs. 1.20±0.35; P≤0.01) 30 minutes pre-intubation, and use noninvasive ventilation before intubation (30 [21%] vs. 15 [12%]; P=0.04). Patients developing PIH had higher ICU and hospital mortality rates (38% vs. 24%; P=0.01; and 49% vs. 37%; P=0.04).
“Awareness of PIH has been increasing due to its effects on morbidity and mortality,” said researcher Nathan J. Smischney, MD, from the Department of Anesthesiology at Mayo Clinic. “Nearly all the literature focuses on the nonimmunocompromised population. However, the immunocompromised population carries inherent risks, which are different than their nonimmunocompromised counterparts.”
Dr. Smischney said the study demonstrates that PIH occurs more frequently in this particular population. “Advanced age, increasing illness severity, use of noninvasive ventilation pre-intubation and pre-intubation hemodynamic instability were significantly associated with PIH,” he said. “Furthermore, those who developed PIH had reduced survival, consistent with the literature.”
PIH Rate High
Cameron Hypes, MD, MPH, assistant professor of emergency and internal medicine at the University of Arizona, in Tucson, who was asked to comment on the study, said although the authors did not compare immunocompromised with nonimmunocompromised patients—a “significant weakness” that makes it difficult to determine whether being immunocompromised is a predictor of PIH—the overall high rate of PIH identified in the study is striking despite its relationship to the immunocompromised. “The high rate of PIH is concerning and suggests predicting or preventing PIH may be a target for improving the safety of tracheal intubation,” Dr. Hypes said.
The study also confirms the finding that an SI greater than 1 before intubation is predictive of PIH, Dr. Hypes said. “Importantly, the authors find that PIH is associated with adverse outcomes like mortality, a finding that is in line with prior studies of PIH, although it remains unclear whether this higher mortality is a consequence of PIH or an association in which more severely ill patients are more likely to both develop PIH as well as die,” he said.
Dr. Hypes said identifying high-risk populations and predictors of PIH seems like a sound strategy for improving the safety of tracheal intubation in the critically ill, and said he expected more studies will be undertaken.
Dr. Smischney said the study benefits anesthesia personnel by providing “a heightened awareness” of PIH when performing general anesthesia. Patients who are immunocompromised, especially with the risk factors identified in the study, should have treatments available to prevent PIH before intubation is performed.
“As an aside, an easily calculated bedside physiologic variable that can be obtained to indicate the likelihood of PIH is MSI and/or SI, which is heart rate divided by mean arterial pressure (MSI) and heart rate divided by systolic blood pressure (SI),” Dr. Smischney said. “Key steps to take to prevent PIH in immunocompromised patients include selecting available sedatives with the least amount of effects on hemodynamics, along with optimal volume status pre-intubation and medications available for treating PIH, should it occur.”