Cool hemodynamics--the intricate interplay between therapeutic hypothermia and the post-cardiac arrest syndrome

Electrocardiographic changes in patients undergoing targeted temperature management

OBJECTIVES

Targeted temperature management is the recommended therapy for comatose patients after an out-of-hospital cardiac arrest resuscitation due to the reduction in neurological damage and improved outcomes. However, there may result in electrocardiographic instability depending on the degree of targeted temperature management, including minor or life-threatening dysrhythmias or conduction delays. This project aims to describe the frequency of ECG interval changes and clinically relevant dysrhythmias in targeted temperature management patients.

METHODS

This is a retrospective observational study from January 2009 to December 2015. Patients who qualified for the study had a non-traumatic cardiac arrest with a return of spontaneous circulation, received targeted temperature management at 33.5°C for 24 hours followed by 16 hours of rewarming. ECG interval changes and dysrhythmias were recorded immediately after return of spontaneous circulation, and at 24 and 48 hours post return of spontaneous circulation.

RESULTS

A total of 322 patients (age 61.0 ± 16.9 years) had targeted temperature management initiated during the study period, of which 169 had complete data and 13 died prior to completing 24 hours of hypothermia. There were statistically significant changes during targeted temperature management in heart rate (96.7 ± 26.0/min before targeted temperature management; 69.5 ± 19.1/min during, P < 0.001), QRS duration (115.1 ± 32.6 ms before targeted temperature management; 107.8 ± 27.9 ms during targeted temperature management, P < 0.001), and QTc (486.3 ± 52.8 ms before targeted temperature management; 526.9 ± 61.7 ms during targeted temperature management, P < 0.001). There were cardiac dysrhythmias that received treatment during cooling and rewarming.

CONCLUSION

During the period of targeted temperature management and rewarming, we observed few self-limiting ECG interval changes and no clinically significant dysrhythmias in this population during the period of targeted temperature management.

Is Procalcitonin a Marker of Neurologic Outcome or Early Infection in Patients Treated with Targeted Temperature Management?

Objectives

Although high procalcitonin (PCT) levels are associated with poor neurological outcomes and increased mortality rates in patients treated with targeted temperature management (TTM) in the postcardiac arrest (CA) period, there are limited data about the correlation between PCT levels and infection. The aim of our study was to assess the relationship of PCT levels in the first 48 hours with early period infections, late period neurological prognosis, and mortality in patients treated with TTM after CA.

Materials and methods

Serum PCT was measured on admission days 1 and 2. The early onset infection diagnosis before the seventh day in the intensive care unit (ICU) was made according to the criteria of infection centers for disease control and prevention. Mortality and neurologic outcomes were assessed 90 days after CA according to cerebral performance category (CPC) score.

Results

There was no statistically significant correlation between early period infection diagnosis and PCT levels at the time of admission, 24th, and 48th hours. Patients with poor neurologic outcomes on the 90th day had significantly high PCT levels at 24 (p = 0.044) and 48 hours (p = 0.004). There was no statistically significant correlation between admission PCT levels and neurological prognosis. While the correlation between mortality and PCT levels at 24 (p = 0.049) and 48 (p = 0.004) hours was significantly high, no statistically significant correlation was found between admission PCT levels and mortality.

Conclusion

In patients treated with TTM after CA, increased PCT levels were significantly correlated with poor neurologic outcomes and mortality. However, the elevated PCT levels were not significantly correlated with early period infections.

How to cite this article

Zincircioglu C, Yavuz T, Sarıtaş A, Çakmak M, Güldoğan IK, Uzun U, et al. Is Procalcitonin a Marker of Neurologic Outcome or Early Infection in Patients Treated with Targeted Temperature Management? Indian J Crit Care Med 2020;24(5):327–331.

Editor's Choice- Inside the cold heart: A review of therapeutic hypothermia cardioprotection

Targeted temperature management has been originally used to reduce neurological injury and improve outcome in patients after out-of-hospital cardiac arrest. Myocardial infarction remains a major cause of death in the world and several investigators are studying the effect of mild therapeutic hypothermia during an acute cardiac ischemic injury. A search on MEDLINE, Scopus and EMBASE databases was conducted to obtain data regarding the cardioprotective properties of therapeutic hypothermia. Preclinical studies have shown that therapeutic hypothermia provides a cardioprotective effect in animals. The proposed pathways for the cardioprotective effects of therapeutic hypothermia include stabilization of mitochondrial permeability, production of nitric oxide, equilibration of reactive oxygen species, and calcium channels homeostasis. Clinical trials in humans have yielded controversial results. Current trials are therefore seeking to combine therapeutic hypothermia with other treatment modalities in order to improve the outcomes of patients with acute ischemic injury. This article provides a review of the hypothermia effects on the cardiovascular system, from the basic science of physiological changes in the human body and molecular mechanisms of cardioprotection to the bench of clinical trials with therapeutic hypothermia in patients with acute ischemic injury.

Review of the Clinical Evidence and Controversies in Therapeutic Hypothermia for Survivors of Sudden Cardiac Death

Sudden cardiac arrest constitutes a major public health burden in both developed and developing countries. In those successfully resuscitated from cardiac arrest, subsequent mortality is still high (∼75%) and is due to a combination of ischaemia and reperfusion injury. The purpose of this review is to describe the experimental and clinical evidence supporting therapeutic hypothermia in survivors of sudden cardiac arrest. We also discuss controversies and unresolved issues in therapeutic hypothermia, including the optimum target temperature for therapeutic hypothermia, and the role of pre-hospital induction of hypothermia. We conclude with a perspective on therapeutic hypothermia as it applies to the Singapore context.