The Association of Fever and Antipyretic Medication With Outcomes in Mechanically Ventilated Patients: A Cohort Study

Factors associated with fever after cardiac arrest: A post-hoc analysis of the FINNRESUSCI study

BACKGROUND

Fever after cardiac arrest may impact outcome. We aimed to assess the incidence of fever in post-cardiac arrest patients, factors predicting fever and its association with functional outcome in patients treated without targeted temperature management (TTM).

METHODS

The FINNRESUSCI observational cohort study in 2010-2011 included intensive care unit (ICU)-treated out-of-hospital cardiac arrest (OHCA) patients from all five Finnish university hospitals and 14 of 15 central hospitals. This post hoc analysis included those FINNRESUSCI study patients who were not treated with TH. We defined fever as at least one temperature measurement of ≥37.8°C within 72 h of ICU admission. The primary outcome was favourable functional outcome at 12 months, defined as cerebral performance category (CPC) of 1 or 2. Binary logistic regression models including witnessed arrest, bystander cardiopulmonary resuscitation (CPR), initial rhythm and delay of return of spontaneous circulation were used to compare the functional outcomes of the groups.

RESULTS

There were 67,428 temperature measurements from 192 patients, of whom 89 (46%) experienced fever. Twelve-month CPC was missing in 7 patients, and 51 (28%) patients had favourable functional outcome at 12 months. The patients with shockable initial rhythms had a lower incidence of fever within 72 h of ICU admission (28% vs. 72%, p < .01), and the patients who experienced fever had a longer median return of spontaneous circulation (ROSC) delay (20 [IQR 10-30] vs. 14 [IQR 9-22] min, p < .01). Only initial non-shockable rhythm (OR 2.99, 95% CI 1.51-5.94) was associated with increased risk of fever within the first 72 h of ICU admission. Neither time in minutes nor area (minutes  ×  degree celsius over threshold) over 37°C, 37.5°C, 38°C, 38.5°C, 39°C, 39.5°C or 40°C were significantly different in those with favourable functional outcome compared to those with unfavourable functional outcome within the first 24, 48 or 72 h from ICU admission. Fever was not associated with favourable functional outcome at 12 months (OR 0.90, 95% CI 0.44-1.84).

CONCLUSIONS

Half of OHCA patients not treated with TTM developed fever. We found no association between fever and outcome.

Temperature control in sepsis

Fever can be viewed as an adaptive response to infection. Temperature control in sepsis is aimed at preventing potential harms associated with high temperature (tachycardia, vasodilation, electrolyte and water loss) and therapeutic hypothermia may be aimed at slowing metabolic activities and protecting organs from inflammation. Although high fever (>39.5°C) control is usually performed in critically ill patients, available cohorts and randomized controlled trials do not support its use to improve sepsis prognosis. Finally, both spontaneous and therapeutic hypothermia are associated with poor outcomes in sepsis.

Fever in the ICU: A Predictor of Mortality in Mechanically Ventilated COVID-19 Patients

PURPOSE

While fever may be a presenting symptom of COVID-19, fever at hospital admission has not been identified as a predictor of mortality. However, hyperthermia during critical illness among ventilated COVID-19 patients in the ICU has not yet been studied. We sought to determine mortality predictors among ventilated COVID-19 ICU patients and we hypothesized that fever in the ICU is predictive of mortality.

MATERIALS AND METHODS

We conducted a retrospective cohort study of 103 ventilated COVID-19 patients admitted to the ICU between March 14 and May 27, 2020. Final follow-up was June 5, 2020. Patients discharged from the ICU or who died were included. Patients still admitted to the ICU at final follow-up were excluded.

RESULTS

103 patients were included, 40 survived and 63(61.1%) died. Deceased patients were older {66 years[IQR18] vs 62.5[IQR10], (p = 0.0237)}, more often male {48(68%) vs 22(55%), (p = 0.0247)}, had lower initial oxygen saturation {86.0%[IQR18] vs 91.5%[IQR11.5], (p = 0.0060)}, and had lower pH nadir than survivors {7.10[IQR0.2] vs 7.30[IQR0.2] (p < 0.0001)}. Patients had higher peak temperatures during ICU stay as compared to hospital presentation {103.3°F[IQR1.7] vs 100.0°F[IQR3.5], (p < 0.0001)}. Deceased patients had higher peak ICU temperatures than survivors {103.6°F[IQR2.0] vs 102.9°F[IQR1.4], (p = 0.0008)}. Increasing peak temperatures were linearly associated with mortality. Febrile patients who underwent targeted temperature management to achieve normothermia did not have different outcomes than those not actively cooled. Multivariable analysis revealed 60% and 75% higher risk of mortality with peak temperature greater than 103°F and 104°F respectively; it also confirmed hyperthermia, age, male sex, and acidosis to be predictors of mortality.

CONCLUSIONS

This is one of the first studies to identify ICU hyperthermia as predictive of mortality in ventilated COVID-19 patients. Additional predictors included male sex, age, and acidosis. With COVID-19 cases increasing, identification of ICU mortality predictors is crucial to improve risk stratification, resource management, and patient outcomes.

Surgical Infection Society Research Priorities: A Narrative Review of Fourteen Years of Progress

Background: In 2006, the Surgical Infection Society (SIS) utilized a modified Delphi approach to define 15 specific priority research questions that remained unanswered in the field of surgical infections. The aim of the current study was to evaluate the scientific progress achieved during the ensuing period in answering each of the 15 research questions and to determine if additional research in these fields is warranted. Methods: For each of the questions, a literature search using the National Center for Biotechnology Information (NCBI) was performed by the Scientific Studies Committee of the SIS to identify studies that attempted to address each of the defined questions. This literature was analyzed and summarized. The data on each question were evaluated by a surgical infections expert to determine if the question was answered definitively or remains unanswered. Results: All 15 priority research questions were studied in the last 14 years; six questions (40%) were definitively answered and 9 questions (60%) remain unanswered in whole or in part, mainly because of the low quality of the studies available on this topic. Several of the 9 unanswered questions were deemed to remain research priorities in 2020 and warrant further investigation. These included, for example, the role of empiric antimicrobial agents in nosocomial infections, the use of inotropes/vasopressors versus volume loading to raise the mean arterial pressure, and the role of increased antimicrobial dosing and frequency in the obese patient. Conclusions: Several surgical infection-related research questions prioritized in 2006 remain unanswered. Further high-quality research is required to provide a definitive answer to many of these priority knowledge gaps. An updated research agenda by the SIS is warranted at this time to define research priorities for the future.

Core warming of coronavirus disease 2019 (COVID-19) patients undergoing mechanical ventilation-A protocol for a randomized controlled pilot study

BACKGROUND

Coronavirus disease 2019 (COVID-19), caused by the virus SARS-CoV-2, is spreading rapidly across the globe, with little proven effective therapy. Fever is seen in most cases of COVID-19, at least at the initial stages of illness. Although fever is typically treated (with antipyretics or directly with ice or other mechanical means), increasing data suggest that fever is a protective adaptive response that facilitates recovery from infectious illness.

OBJECTIVE

To describe a randomized controlled pilot study of core warming patients with COVID-19 undergoing mechanical ventilation.

METHODS

This prospective single-site randomized controlled pilot study will enroll 20 patients undergoing mechanical ventilation for respiratory failure due to COVID-19. Patients will be randomized 1:1 to standard-of-care or to receive core warming via an esophageal heat exchanger commonly utilized in critical care and surgical patients. The primary outcome is patient viral load measured by lower respiratory tract sample. Secondary outcomes include severity of acute respiratory distress syndrome (as measured by PaO2/FiO2 ratio) 24, 48, and 72 hours after initiation of treatment, hospital and intensive care unit length of stay, duration of mechanical ventilation, and 30-day mortality.

RESULTS

Resulting data will provide effect size estimates to guide a definitive multi-center randomized clinical trial. ClinicalTrials.gov registration number: NCT04426344.

CONCLUSIONS

With growing data to support clinical benefits of elevated temperature in infectious illness, this study will provide data to guide further understanding of the role of active temperature management in COVID-19 treatment and provide effect size estimates to power larger studies.

Moderate Fever Cycles as a Potential Mechanism to Protect the Respiratory System in COVID-19 Patients

Mortality in COVID-19 patients predominantly results from an acute respiratory distress syndrome (ARDS), in which lungs alveolar cells undergo programmed cell death. Mortality in a sepsis-induced ARDS rat model is reduced by adenovirus over-expression of the HSP70 chaperone. A natural rise of body temperature during mild fever can naturally accumulate high cellular levels of HSP70 that can arrest apoptosis and protect alveolar lung cells from inflammatory damages. However, beyond 1-2 h of fever, no HSP70 is being further produced and a decreased in body temperature required to the restore cell's ability to produce more HSP70 in a subsequent fever cycle. We suggest that antipyretics may be beneficial in COVID-19 patients subsequent to several hours of mild (<38.8°C) advantageous fever, allowing lung cells to accumulate protective HSP70 against damages from the inflammatory response to the virus SARS-CoV-2. With age, the ability to develop fever and accumulate HSP70 decreases. This could be ameliorated, when advisable to do so, by thermotherapies and/or physical training.

The Use of Core Warming as a Treatment for Coronavirus Disease 2019 (COVID-19): an Initial Mathematical Model

Background: Increasing data suggest that elevated body temperature may be helpful in resolving a variety of diseases, including sepsis, acute respiratory distress syndrome (ARDS), and viral illnesses. SARS-CoV-2, which causes coronavirus disease 2019 (COVID-19), may be more temperature sensitive than other coronaviruses, particularly with respect to the binding affinity of its viral entry via the ACE2 receptor. A mechanical provision of elevated temperature focused in a body region of high viral activity in patients undergoing mechanical ventilation may offer a therapeutic option that avoids arrhythmias seen with some pharmaceutical treatments. We investigated the potential to actively provide core warming to the lungs of patients with a commercially available heat transfer device via mathematical modeling, and examine the influence of blood perfusion on temperature using this approach. Methods: Using the software Comsol Multiphysics, we modeled and simulated heat transfer in the body from an intraesophageal warming device, taking into account the airflow from patient ventilation. The simulation was focused on heat transfer and warming of the lungs and performed on a simplified geometry of an adult human body and airway from the pharynx to the lungs. Results: The simulations were run over a range of values for blood perfusion rate, which was a parameter expected to have high influence in overall heat transfer, since the heat capacity and density remain almost constant. The simulation results show a temperature distribution which agrees with the expected clinical experience, with the skin surface at a lower temperature than the rest of the body due to convective cooling in a typical hospital environment. The highest temperature in this case is the device warming water temperature, and that heat diffuses by conduction to the nearby tissues, including the air flowing in the airways. At the range of blood perfusion investigated, maximum lung temperature ranged from 37.6°C to 38.6°C. Conclusions: The provision of core warming via commercially available technology currently utilized in the intensive care unit, emergency department, and operating room can increase regional temperature of lung tissue and airway passages. This warming may offer an innovative approach to treating infectious diseases from viral illnesses such as COVID-19, while avoiding the arrhythmogenic complications of currently used pharmaceutical treatments.