Fever in non-neurological critically ill patients: a systematic review of observational studies

Development and validation of a nomogram for predicting in-hospital death in cirrhotic patients with acute kidney injury

BACKGROUND

The purpose of this study was to develop a nomogram for predicting in-hospital mortality in cirrhotic patients with acute kidney injury (AKI) in order to identify patients with a high risk of in-hospital death early.

METHODS

This study collected data on cirrhotic patients with AKI from 2008 to 2019 using the Medical Information Mart for Intensive Care IV. Multivariate logistic regression was used to identify confounding factors related to in-hospital mortality, which were then integrated into the nomogram. The concordance index (C-Index) was used to evaluate the accuracy of the model predictions. The area under the curve (AUC) and decision curve analysis (DCA) was used to assess the predictive performance and clinical utility of the nomogram.

RESULTS

The final study population included 886 cirrhotic patients with AKI, and 264 (29.8%) died in the hospital. After multivariate logistic regression, age, gender, cerebrovascular disease, heart rate, respiration rate, temperature, oxygen saturation, hemoglobin, blood urea nitrogen, serum creatinine, international normalized ratio, bilirubin, urine volume, and sequential organ failure assessment score were predictive factors of in-hospital mortality. In addition, the nomogram showed good accuracy in estimating the in-hospital mortality of patients. The calibration plots showed the best agreement with the actual presence of in-hospital mortality in patients. In addition, the AUC and DCA curves showed that the nomogram has good prediction accuracy and clinical value.

CONCLUSIONS

We have created a prognostic nomogram for predicting in-hospital death in cirrhotic patients with AKI, which may facilitate timely intervention to improve prognosis in these patients.

Antipyretic Use in Noncritically Ill Patients With Fever: A Review

Antipyretics are one of the most frequently used agents in medicine. Numerous pharmacological agents, such as acetaminophen, non-steroidal anti-inflammatory agents (NSAIDs), salicylates, and selective cyclooxygenase 2 (COX-2) inhibitors, and nonpharmacological treatment modalities, such as tepid sponging and cooling blankets, are available for temperature reduction. There is a scarcity of definitive clinical guidelines on the choice of various agents in noncritically ill febrile patients. Our review examined the various modalities available for antipyresis and compared their safety and efficacy. The rationale for the choice of a particular pharmacological agent and route of administration were scrutinized. Our review also envisaged the perceived beneficial effects of antipyretics against the harmful side effects, including the evaluation of morbidity or mortality advantage conferred by antipyretics. The various toxicities associated with these agents were also highlighted.

Current State of Knowledge on the Definition, Pathophysiology, Etiology, Outcomes, and Management of Fever in the Intensive Care Unit

Fever-an elevated body temperature-is a prominent feature of a wide range of disease conditions and is a common finding in intensive care, affecting up to 70% of patients in the intensive care unit (ICU). The causes of fever in the ICU are multifactorial, and it can be due to a number of infective and noninfective etiologies. The production of fever represents a complex physiological, adaptive host response that is beneficial for host defense and survival but can be maladaptive and harmful if left unabated. Despite any cause, fever is associated with a wide range of cellular, local, and systemic effects, including multiorgan dysfunction, systemic inflammation, poor neurological recovery, and an increased risk of mortality. This narrative review presents the current state-of-the-art knowledge on the definition, pathophysiology, etiology, and outcomes of fever in the ICU and highlights evidence-based findings regarding the management of fever in the intensive care setting.

Society of Critical Care Medicine and the Infectious Diseases Society of America Guidelines for Evaluating New Fever in Adult Patients in the ICU

RATIONALE

Fever is frequently an early indicator of infection and often requires rigorous diagnostic evaluation.

OBJECTIVES

This is an update of the 2008 Infectious Diseases Society of America and Society (IDSA) and Society of Critical Care Medicine (SCCM) guideline for the evaluation of new-onset fever in adult ICU patients without severe immunocompromise, now using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology.

PANEL DESIGN

The SCCM and IDSA convened a taskforce to update the 2008 version of the guideline for the evaluation of new fever in critically ill adult patients, which included expert clinicians as well as methodologists from the Guidelines in Intensive Care, Development and Evaluation Group. The guidelines committee consisted of 12 experts in critical care, infectious diseases, clinical microbiology, organ transplantation, public health, clinical research, and health policy and administration. All task force members followed all conflict-of-interest procedures as documented in the American College of Critical Care Medicine/SCCM Standard Operating Procedures Manual and the IDSA. There was no industry input or funding to produce this guideline.

METHODS

We conducted a systematic review for each population, intervention, comparison, and outcomes question to identify the best available evidence, statistically summarized the evidence, and then assessed the quality of evidence using the GRADE approach. We used the evidence-to-decision framework to formulate recommendations as strong or weak or as best-practice statements.

RESULTS

The panel issued 12 recommendations and 9 best practice statements. The panel recommended using central temperature monitoring methods, including thermistors for pulmonary artery catheters, bladder catheters, or esophageal balloon thermistors when these devices are in place or accurate temperature measurements are critical for diagnosis and management. For patients without these devices in place, oral or rectal temperatures over other temperature measurement methods that are less reliable such as axillary or tympanic membrane temperatures, noninvasive temporal artery thermometers, or chemical dot thermometers were recommended. Imaging studies including ultrasonography were recommended in addition to microbiological evaluation using rapid diagnostic testing strategies. Biomarkers were recommended to assist in guiding the discontinuation of antimicrobial therapy. All recommendations issued were weak based on the quality of data.

CONCLUSIONS

The guidelines panel was able to formulate several recommendations for the evaluation of new fever in a critically ill adult patient, acknowledging that most recommendations were based on weak evidence. This highlights the need for the rapid advancement of research in all aspects of this issue-including better noninvasive methods to measure core body temperature, the use of diagnostic imaging, advances in microbiology including molecular testing, and the use of biomarkers.

Associations Between Core Temperature Disorders and Outcomes of Pediatric Intensive Care Unit Patients

BACKGROUND

The few studies of associations between fever and outcomes in pediatric intensive care unit (PICU) patients have conflicting findings. Associations between hypothermia and patient outcomes have not been studied.

OBJECTIVE

To investigate the incidence and characteristics of fever and hypothermia and their associations with adverse outcomes among PICU patients.

METHODS

Patients consecutively admitted to 2 PICUs in a 2-year period were prospectively studied. Core temperature was mainly measured by rectal or axillary thermometry. Fever and hypothermia were defined as core temperatures of greater than 38.0 °C and less than 36.0 °C, respectively. Prolonged mechanical ventilation, prolonged PICU stay, and PICU mortality were the adverse patient outcomes studied. Associations between patient outcomes and core temperature disorders were evaluated with univariate comparisons and multivariate analyses.

RESULTS

Of 545 patients enrolled, fever occurred in 299 (54.9%) and hypothermia occurred in 161 (29.5%). Both temperature disorders were independently associated with prolonged mechanical ventilation and prolonged PICU stay (P < .001) but not with PICU mortality. Late onset of fever (P < .001) and hypothermia (P = .009) were independently associated with prolonged mechanical ventilation, fever magnitude and duration (both P < .001) were independently associated with prolonged PICU stay, and fever magnitude (P < .001) and infectious cause of hypothermia (P= .01) were independently associated with higher PICU mortality.

CONCLUSIONS

These findings provide evidence that the manifestation and characteristics of fever and hypothermia are independent predictors of adverse outcomes in PICU patients.

Temperature Trajectory Subphenotypes in Oncology Patients with Neutropenia and Suspected Infection

Rationale: Despite etiologic and severity heterogeneity in neutropenic sepsis, management is often uniform. Understanding host response clinical subphenotypes might inform treatment strategies for neutropenic sepsis. Objectives: In this retrospective two-hospital study, we analyzed whether temperature trajectory modeling could identify distinct, clinically relevant subphenotypes among oncology patients with neutropenia and suspected infection. Methods: Among adult oncologic admissions with neutropenia and blood cultures within 24 hours, a previously validated model classified patients' initial 72-hour temperature trajectories into one of four subphenotypes. We analyzed subphenotypes' independent relationships with hospital mortality and bloodstream infection using multivariable models. Measurements and Main Results: Patients (primary cohort n = 1,145, validation cohort n = 6,564) fit into one of four temperature subphenotypes. "Hyperthermic slow resolvers" (pooled n = 1,140 [14.8%], mortality n = 104 [9.1%]) and "hypothermic" encounters (n = 1,612 [20.9%], mortality n = 138 [8.6%]) had higher mortality than "hyperthermic fast resolvers" (n = 1,314 [17.0%], mortality n = 47 [3.6%]) and "normothermic" (n = 3,643 [47.3%], mortality n = 196 [5.4%]) encounters (P < 0.001). Bloodstream infections were more common among hyperthermic slow resolvers (n = 248 [21.8%]) and hyperthermic fast resolvers (n = 240 [18.3%]) than among hypothermic (n = 188 [11.7%]) or normothermic (n = 418 [11.5%]) encounters (P < 0.001). Adjusted for confounders, hyperthermic slow resolvers had increased adjusted odds for mortality (primary cohort odds ratio, 1.91 [P = 0.03]; validation cohort odds ratio, 2.19 [P < 0.001]) and bloodstream infection (primary odds ratio, 1.54 [P = 0.04]; validation cohort odds ratio, 2.15 [P < 0.001]). Conclusions: Temperature trajectory subphenotypes were independently associated with important outcomes among hospitalized patients with neutropenia in two independent cohorts.

Impact of an Educational Program on Improving Nurses’ Management of Fever: An Experimental Study

Background: Despite a public information campaign “To Break the Myth of Fever”, nurses continued to overtreat fever. This study hypothesized that the campaign lacked the detailed rationale essential to alter nurses’ attitudes and behaviors. Aim: To evaluate the effect of the educational program on nurses’ knowledge, attitudes, and behaviors related to fever management. Design: A randomized experimental design using a time series analysis. Methods: A random sample of 58 medical/surgical nurses was evenly divided into an intervention and a control group. The intervention group received an educational program on fever and fever management. Both groups completed a pretest and four posttests using investigator-developed instruments: a questionnaire on knowledge and attitudes about fever management and a fever treatment checklist to audit charts. Results: The intervention group had markedly higher knowledge scores and reduced use of ice pillows at all four posttests, as well as lower use of antipyretics overall, except for the first posttest, despite no sustained change in attitude. Conclusions: An educational program for fever management can effectively improve clinical nurses’ knowledge and attitudes about fever management.

The association between the degree of fever as measured in the emergency department and clinical outcomes of hospitalized adult patients

BACKGROUND

Fever is a physiologic response to a wide range of pathologies and one of the most common complaints and clinical signs in the emergency medicine department (ED). The association between fever magnitude and clinical outcomes has been evaluated in specific populations with inconsistent results.

OBJECTIVES

In this study we aimed to investigate the association between the degree of fever in the ED and clinical outcomes of hospitalized febrile adult patients.

METHODS

This was a retrospective single-center cohort study of all the patients with maximal body temperature (BT) ≥ 38.0 °C, as recorded during the ED evaluation, who were hospitalized between January 2015 and December 2020. Patients with heatstroke were excluded. The primary outcome was 30-day all-cause mortality and secondary outcomes were intensive care unit (ICU) admission and development of acute kidney injury (AKI).

RESULTS

Fever was recorded among 8.1% of patients evaluated in the ED. Elevated BT was associated with increased risk of hospital admission (70.3% vs. 49.4%, p < 0.001), 30-day mortality (12.3% vs. 2.6%, p < 0.001), ICU admission (5.7% vs. 2.8%, p < 0.001), and AKI 11.7% vs. 3.8%, p < 0.001). After exclusion of nine patients with heatstroke, 21,252 hospitalized febrile patients were included in the final analysis. BT > 39.7 °C was progressively associated with increased mortality (OR 1.64-2.22, 95% CI 1.16-2.81, p < 0.005) as compared to BT 38.0-38.1 °C. More AKI events were observed in patients with BT > 39.5 °C (OR 1.48-2.91, 95% CI 1.11-3.66, p < 0.007). Temperature between 39.2 and 39.5 °C was associated with lower mortality (OR 0.62-0.71, 95% CI 0.51-0.87, p < 0.001). In a multiple logistic regression analysis BT > 39.9 °C was independently associated with increased mortality and AKI. BT > 39.7 °C was progressively associated with an increased risk of ICU admission.

CONCLUSION

Among febrile patients admitted to the hospital, BT > 39.5 °C was associated with adverse clinical course, as compared to patients with lower-grade fever (38.0-38.1 °C). These patients should be flagged on arrival to the ED and likely warrant more aggressive evaluation and treatment.

An integrated perspective on transmutation of acute inflammation into chronic and the role of the microbiome

The Continuum theory and the Levels of Health theory were separately proposed to explain the myriad responses to treatment and understand the process of health and disease in an individual. In light of accumulating evidence on the intricate relationship between the human immune system and microbiome, an attempt is made in this article to connect these two theories to explain the transmutation of the efficiently responding immune system (through the acute inflammatory response and high fever) to one involved in a low-grade chronic inflammatory process (resulting in chronic disease). There is already enough evidence to demonstrate the role of the microbiome in all chronic inflammatory diseases. In this article, we discuss the mechanism by which subjecting a healthy person to continuous drug treatment for acute inflammatory conditions (at a certain time) leads to transmutation to chronic disease. Although this hypothesis requires further experimental evidence, it calls for a reconsideration of the manner in which we treat acute infectious diseases in the population.

The Effect of Early Sedation With Dexmedetomidine on Body Temperature in Critically Ill Patients

OBJECTIVES

Previous case series reported an association between dexmedetomidine use and hyperthermia. Temperature data have not been systematically reported in previous randomized controlled trials evaluating dexmedetomidine. A causal link between dexmedetomidine administration and elevated temperature has not been demonstrated.

DESIGN

Post hoc analysis.

SETTING

Four ICUs in Australia and New Zealand.

PATIENTS

About 703 mechanically ventilated ICU patients.

INTERVENTIONS

Early sedation with dexmedetomidine versus usual care.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was mean daily body temperature. Secondary outcomes included the proportions of patients with body temperatures greater than or equal to 38.3°C and greater than or equal to 39°C, respectively. Outcomes were recorded for 5 days postrandomization in the ICU. The mean daily temperature was not different between the dexmedetomidine (n = 351) and usual care (n = 352) groups (36.84°C ± sd vs 36.78°C ± sd; p = 0.16). Over the first 5 ICU days, more dexmedetomidine group (vs usual care) patients had a temperature greater than or equal to 38.3°C (43.3% vs 32.7%, p = 0.004; absolute difference 10.6 percentage points) and greater than or equal to 39.0°C (19.4% vs 12.5%, p = 0.013; absolute difference 6.9 percentage points). Results were similar after adjusting for diagnosis, admitting temperature, age, weight, study site, sepsis occurrence, and the time from dexmedetomidine initiation to first hyperthermia recorded. There was a significant dose response relationship with temperature increasing by 0.30°C ±0.08 for every additional 1 μg/kg/hr of dexmedetomidine received p < 0.0002.

CONCLUSIONS

Our study suggests potentially important elevations in body temperature are associated with early dexmedetomidine sedation, in adults who are mechanically ventilated in the ICU.

Different temperature thresholds for antipyretic intervention in critically ill children with fever due to infection: the FEVER feasibility RCT

BACKGROUND

Fever accelerates host immune system control of pathogens but at a high metabolic cost. The optimal approach to fever management and the optimal temperature thresholds used for treatment in critically ill children are unknown.

OBJECTIVES

To determine the feasibility of conducting a definitive randomised controlled trial (RCT) to evaluate the clinical effectiveness and cost-effectiveness of different temperature thresholds for antipyretic management.

DESIGN

A mixed-methods feasibility study comprising three linked studies - (1) a qualitative study exploring parent and clinician views, (2) an observational study of the epidemiology of fever in children with infection in paediatric intensive care units (PICUs) and (3) a pilot RCT with an integrated-perspectives study.

SETTING

Participants were recruited from (1) four hospitals in England via social media (for the FEVER qualitative study), (2) 22 PICUs in the UK (for the FEVER observational study) and (3) four PICUs in England (for the FEVER pilot RCT).

PARTICIPANTS

(1) Parents of children with relevant experience were recruited to the FEVER qualitative study, (2) patients who were unplanned admissions to PICUs were recruited to the FEVER observational study and (3) children admitted with infection requiring mechanical ventilation were recruited to the FEVER pilot RCT. Parents of children and clinicians involved in the pilot RCT.

INTERVENTIONS

The FEVER qualitative study and the FEVER observational study had no interventions. In the FEVER pilot RCT, children were randomly allocated (1 : 1) using research without prior consent (RWPC) to permissive (39.5 °C) or restrictive (37.5 °C) temperature thresholds for antipyretics during their PICU stay while mechanically ventilated.

MAIN OUTCOME MEASURES

(1) The acceptability of FEVER, RWPC and potential outcomes (in the FEVER qualitative study), (2) the size of the potentially eligible population and the temperature thresholds used (in the FEVER observational study) and (3) recruitment and retention rates, protocol adherence and separation between groups and distribution of potential outcomes (in the FEVER pilot RCT).

RESULTS

In the FEVER qualitative study, 25 parents were interviewed and 56 clinicians took part in focus groups. Both the parents and the clinicians found the study acceptable. Clinicians raised concerns regarding temperature thresholds and not using paracetamol for pain/discomfort. In the FEVER observational study, 1853 children with unplanned admissions and infection were admitted to 22 PICUs between March and August 2017. The recruitment rate was 10.9 per site per month. The majority of critically ill children with a maximum temperature of > 37.5 °C received antipyretics. In the FEVER pilot RCT, 100 eligible patients were randomised between September and December 2017 at a recruitment rate of 11.1 per site per month. Consent was provided for 49 out of 51 participants in the restrictive temperature group, but only for 38 out of 49 participants in the permissive temperature group. A separation of 0.5 °C (95% confidence interval 0.2 °C to 0.8 °C) between groups was achieved. A high completeness of outcome measures was achieved. Sixty parents of 57 children took part in interviews and/or completed questionnaires and 98 clinicians took part in focus groups or completed a survey. Parents and clinicians found the pilot RCT and RWPC acceptable. Concerns about children being in pain/discomfort were cited as reasons for withdrawal and non-consent by parents and non-adherence to the protocol by clinicians.

LIMITATIONS

Different recruitment periods for observational and pilot studies may not fully reflect the population that is eligible for a definitive RCT.

CONCLUSIONS

The results identified barriers to delivering the definitive FEVER RCT, including acceptability of the permissive temperature threshold. The findings also provided insight into how these barriers may be overcome, such as by limiting the patient inclusion criteria to invasive ventilation only and by improved site training. A definitive FEVER RCT using a modified protocol should be conducted, but further work is required to agree important outcome measures for clinical trials among critically ill children.

TRIAL REGISTRATION

The FEVER observational study is registered as NCT03028818 and the FEVER pilot RCT is registered as Current Controlled Trials ISRCTN16022198.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 5. See the NIHR Journals Library website for further project information.

Non-infectious Fever After Acute Spinal Cord Injury in the Intensive Care Unit

OBJECTIVE

The aim of the present study is to evaluate the frequency, etiology, risk factors and clinical outcomes in acute traumatic SCI patients who develop fever and to evaluate the relationship between fever and mortality.

DESIGN

Retrospective data were collected between January 2007 and August 2016 from patients diagnosed with persistent fever from SCI cases observed in the ICU.

PARTICIPANTS

Among 5370 intensive care patients, 435 SCI patients were evaluated for the presence of fever. A total of 52 patients meeting the criteria were evaluated.

OUTCOME MEASURES

Fever characteristics were evaluated by dividing the patients into two groups: infectious (group-1) and non-infectious (group-2) fever. Demographic and clinical data, ICU and hospital stay, and mortality were evaluated.

RESULTS

In the patients with noninfectious fever, mortality was significantly higher compared to the group with infectious fever (P < 0.001). Of 52 acute SCI cases, 25 (48.1%) had neurogenic fever that did not respond to treatment in intensive care follow-up, and 22 (88%) of these patients died. Maximal fever was 39.10 ± 0.64 °C in Group-1 and 40.22 ± 1.10 ° C in Group-2 (P = 0.001). There was a significant difference in the duration of ICU stay and hospital stay between the two groups (P = 0.005, P = 0.001, respectively), while there was no difference in the duration of mechanical ventilation between the groups (P = 0.544).

CONCLUSION

This study demonstrates that patients diagnosed with neurogenic fever following SCI had higher average body temperature and higher rates of mortality compared to patients diagnosed with infectious fever.

[Fever in the critically ill : To treat or not to treat]

Fever, arbitrarily defined as a core body temperature >38.3 °C, is present in 20-70 % of intensive care unit patients. Fever caused by infections is a physiologic reset of the thermostatic set-point and is associated with beneficial consequences, but may have negative sequelae with temperatures >39.5 °C. Fever of non-infectious and neurologic origin affects about 50 % of patients with elevated body temperature, presents as a pathologic loss of thermoregulation, and may be associated with untoward side effects at temperatures above 38.5-39.0 °C. Cooling can be achieved by physical and pharmacologic means. Evidence-based recommendations are not available. The indication for a cooling therapy can only be based on the physiologic reserve and the neurologic, hemodynamic, and respiratory state. The temperature should be lowered to the normothermic range. Hyperthermia syndromes require immediate physical cooling (and dantrolen when indicated).

Rectal and Bladder Temperatures vs Forehead Core Temperatures Measured With SpotOn Monitoring System

BACKGROUND

Methods and frequency of temperature monitoring in intensive care unit patients vary widely. The recently available SpotOn system uses zero-heat-flux technology and offers a noninvasive method for continuous monitoring of core temperature of critical care patients at risk for alterations in body temperature.

OBJECTIVE

To evaluate agreement between and precision of a zero-heat-flux thermometry system (SpotOn) and continuous rectal and urinary bladder thermometry during fever and defervescence in adult patients in intensive care units.

METHODS

Prospective comparison of SpotOn vs rectal and urinary bladder thermometry in eligible patients enrolled in a randomized clinical trial on the effect of acetaminophen on core body temperature and hemodynamic status.

RESULTS

A total of 748 paired temperature measurements from 38 patients who had both SpotOn monitoring and either continuous rectal or continuous bladder thermometry were analyzed. Temperatures during the study were from 36.6°C to 39.9°C. The mean difference for SpotOn compared with bladder thermometry was -0.07°C (SD, 0.24°C; 95% limits of agreement, ± 0.47°C [-0.54°C, 0.40°C]). The mean difference for SpotOn compared with rectal thermometry was -0.24°C (SD, 0.29°C; 95% limits of agreement, ± 0.57°C [-0.81°C, 0.33°C]). Most differences in temperature between methods were within ± 0.5°C in both groups (96% bladder and 85% rectal).

CONCLUSIONS

The SpotOn thermometry system has excellent agreement and good precision and is a potential alternative for noninvasive continuous monitoring of core temperature in critical care patients, especially when alternative methods are contraindicated or not available.

Pyrexia: aetiology in the ICU

Elevation in core body temperature is one of the most frequently detected abnormal signs in patients admitted to adult ICUs, and is associated with increased mortality in select populations of critically ill patients. The definition of an elevated body temperature varies considerably by population and thermometer, and is commonly defined by a temperature of 38.0 °C or greater. Terms such as hyperthermia, pyrexia, and fever are often used interchangeably. However, strictly speaking hyperthermia refers to the elevation in body temperature that occurs without an increase in the hypothalamic set point, such as in response to specific environmental (e.g., heat stroke), pharmacologic (e.g., neuroleptic malignant syndrome), or endocrine (e.g., thyrotoxicosis) stimuli. On the other hand, pyrexia and fever refer to the classical increase in body temperature that occurs in response to a vast list of infectious and noninfectious aetiologies in association with an increase in the hypothalamic set point. In this review, we examine the contemporary literature investigating the incidence and aetiology of pyrexia and hyperthermia among medical and surgical patients admitted to adult ICUs with or without an acute neurological condition. A temperature greater than 41.0 °C, although occasionally observed among patients with infectious or noninfectious pyrexia, is more commonly observed in patients with hyperthermia. Most episodes of pyrexia are due to infections, but incidence estimates of infectious and noninfectious aetiologies are limited by studies with small sample size and inconsistent reporting of noninfectious aetiologies. Pyrexia commonly triggers a full septic work-up, but on its own is a poor predictor of culture-positivity. In order to improve culturing practices, and better guide the diagnostic approach to critically ill patients with pyrexia, additional research is required to provide more robust estimates of the incidence of infectious and noninfectious aetiologies, and their relationship to other clinical features (e.g., leukocytosis). In the meantime, using existing literature, we propose an approach to identifying the aetiology of pyrexia in critically ill adults.

Controversies in the temperature management of critically ill patients

Although body temperature is a classic primary vital sign, its value has received little attention compared with the others (blood pressure, heart rate, and respiratory rate). This may result from the fact that unlike the other primary vital signs, aging and diseases rarely affect the thermoregulatory system. Despite this, when humans are exposed to various anesthetics and analgesics and acute etiologies of non-infectious and infectious diseases in perioperative and intensive care settings, abnormalities may occur that shift body temperature up and down. A recent upsurge in clinical evidence in the perioperative and critical care field resulted in many clinical trials in temperature management. The results of these clinical trials suggest that aggressive body temperature modifications in comatose survivors after resuscitation from shockable rhythm, and permissive fever in critically ill patients, are carried out in critical care settings to improve patient outcomes; however, its efficacy remains to be elucidated. A recent, large multicenter randomized controlled trial demonstrated contradictory results, which may disrupt the trends in clinical practice. Thus, updated information concerning thermoregulatory interventions is essential for anesthesiologists and intensivists. Here, recent controversies in therapeutic hypothermia and fever management are summarized, and their relevance to the physiology of human thermoregulation is discussed.

A Fever in Acute Aortic Dissection is Caused by Endogenous Mediators that Influence the Extrinsic Coagulation Pathway and Do Not Elevate Procalcitonin

Objective A fever is observed in approximately one-third of cases of acute aortic dissection (AAD); however, the causes remain unclear. We investigated the mechanism of a fever in AAD by measuring the serum concentrations of inflammatory markers, mediators of coagulation and fibrinolysis, and procalcitonin, a marker of bacterial infection. Methods We retrospectively studied 43 patients with medically treated AAD without apparent infection. Patients were divided into those with (Group A; n=19) and without (Group B; n=24) a maximum body temperature >38°C. We established which patients fulfilled the criteria for systemic inflammatory response syndrome (SIRS), and its relationship with a fever was examined. Mediators of inflammation, coagulation and fibrinolysis were compared by a univariate analysis. Factors independently associated with a fever were established by a multivariate analysis. Results The criteria for SIRS were fulfilled in a greater proportion of patients in Group A (79%) than in Group B (42%, p=0.001). There was no difference in the procalcitonin concentration between Groups A and B (0.15±0.17 ng/mL vs. 0.11±0.12 ng/mL, respectively; p=0.572). Serum procalcitonin concentrations lay within the normal range in all patients in whom it was measured, which showed that the fever was caused by endogenous mediators. On the multivariate analysis, there was a borderline significant relationship between a fever and the prothrombin time-International Normalized Ratio (p=0.065), likely reflecting the extrinsic pathway activity initiated by tissue factor. Conclusion Our findings suggest that a fever in AAD could be caused by SIRS, provoked by endogenous mediators that influence the extrinsic coagulation pathway without elevating the serum procalcitonin concentration.

Paracetamol therapy and outcome of critically ill patients: a multicenter retrospective observational study

Introduction

In this study, we aimed to examine the association between paracetamol administration in the intensive care unit (ICU) and mortality in critically ill patients.

Methods

We conducted a multicenter retrospective observational study in four ICUs. We obtained information on paracetamol use, body temperature, demographic, clinical and outcome data from each hospital’s clinical information system and admissions and discharges database. We performed statistical analysis to assess the association between paracetamol administration and hospital mortality.

Results

We studied 15,818 patients with 691,348 temperature measurements at 4 ICUs. Of these patients, 10,046 (64%) received at least 1 g of paracetamol. Patients who received paracetamol had lower in-hospital mortality (10% vs. 20%, P <0.001), and survivors were more likely to have received paracetamol (66% vs. 46%; P <0.001). However, patients treated with paracetamol were also more likely to be admitted to the ICU after surgery (70% vs. 51%; P <0.001) and/or after elective surgery (55% vs. 37%; P <0.001). In multivariate logistic regression analysis including a propensity score for paracetamol treatment, we found a significant and independent association between the use of paracetamol and reduced in-hospital mortality (adjusted odds ratio =0.60 (95% confidence interval (CI), 0.53 to 0.68), P <0.001). Cox proportional hazards analysis showed that patients who received paracetamol also had a significantly longer time to death (adjusted hazard ratio =0.51 (95% CI, 0.46 to 0.56), P <0.001). The association between paracetamol and decreased mortality and/or time to death was broadly consistent across surgical and medical patients. It remained present after adjusting for paracetamol administration as a time-dependent variable. However, when such time-dependent analysis was performed, the association of paracetamol with outcome lost statistical significance in the presence of fever and suspected infection and in patients in the lower tertiles of Acute Physiology and Chronic Health Evaluation II scores.

Conclusions

Paracetamol administration is common in the ICU and appears to be independently associated with reduced in-hospital mortality and time to death after adjustment for multiple potential confounders and propensity score. This association, however, was modified by the presence of fever, suspected infection and lesser illness severity and may represent the effect of indication bias.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0865-1) contains supplementary material, which is available to authorized users.

Does paracetamol help or hinder healing in bacterial infections?

Community nursing teams, alongside other primary care services and nurses in working in community hospitals, are caring for people who are older, sicker and require more complex care. The nurse's ability to use evidence to make informed judgements is vitally important to patient care. Nurses often give paracetamol that is prescribed on an 'as required' basis to patients with bacterial infections who are pyrexial. This practice is supported by guidelines from the National Institute of Health and Care Excellence and the British National Formulary. This article reviews the evidence and suggests that the administration of paracetamol in people with pyrexia should be reconsidered and given on an individualised basis rather than as a routine.

Body temperature abnormalities in non-neurological critically ill patients: a review of the literature

Body temperature abnormalities, which occur because of several infectious and non-infectious etiologies, are among the most commonly noted symptoms of critically ill patients. These abnormalities frequently trigger changes in patient management. The purpose of this article was to review the contemporary literature investigating the definition and occurrence of body temperature abnormalities in addition to their impact on illness severity and mortality in critically ill non-neurological patients, particularly in patients with severe sepsis. Reports on the influence of fever on outcomes are inconclusive, and the presence of fever per se may not contribute to increased mortality in critically ill patients. In patients with severe sepsis, the impacts of elevated body temperature and hypothermia on mortality and the severity of physiologic decline are different. Hypothermia is significantly associated with an increased risk of mortality. In contrast, elevated body temperature may not be associated with increased disease severity or risk of mortality. In patients with severe sepsis, the effect of fever and fever control on outcomes requires further research.

Body temperature patterns as a predictor of hospital-acquired sepsis in afebrile adult intensive care unit patients: a case-control study

Introduction

Early treatment of sepsis improves survival, but early diagnosis of hospital-acquired sepsis, especially in critically ill patients, is challenging. Evidence suggests that subtle changes in body temperature patterns may be an early indicator of sepsis, but data is limited. The aim of this study was to examine whether abnormal body temperature patterns, as identified by visual examination, could predict the subsequent diagnosis of sepsis in afebrile critically ill patients.

Methods

Retrospective case-control study of 32 septic and 29 non-septic patients in an adult medical and surgical ICU. Temperature curves for the period starting 72 hours and ending 8 hours prior to the clinical suspicion of sepsis (for septic patients) and for the 72-hour period prior to discharge from the ICU (for non-septic patients) were rated as normal or abnormal by seven blinded physicians. Multivariable logistic regression was used to compare groups in regard to maximum temperature, minimum temperature, greatest change in temperature in any 24-hour period, and whether the majority of evaluators rated the curve to be abnormal.

Results

Baseline characteristics of the groups were similar except the septic group had more trauma patients (31.3% vs. 6.9%, p = .02) and more patients requiring mechanical ventilation (75.0% vs. 41.4%, p = .008). Multivariable logistic regression to control for baseline differences demonstrated that septic patients had significantly larger temperature deviations in any 24-hour period compared to control patients (1.5°C vs. 1.1°C, p = .02). An abnormal temperature pattern was noted by a majority of the evaluators in 22 (68.8%) septic patients and 7 (24.1%) control patients (adjusted OR 4.43, p = .017). This resulted in a sensitivity of 0.69 (95% CI [confidence interval] 0.50, 0.83) and specificity of 0.76 (95% CI 0.56, 0.89) of abnormal temperature curves to predict sepsis. The median time from the temperature plot to the first culture was 9.40 hours (IQR [inter-quartile range] 8.00, 18.20) and to the first dose of antibiotics was 16.90 hours (IQR 8.35, 34.20).

Conclusions

Abnormal body temperature curves were predictive of the diagnosis of sepsis in afebrile critically ill patients. Analysis of temperature patterns, rather than absolute values, may facilitate decreased time to antimicrobial therapy.

Association of body temperature and antipyretic treatments with mortality of critically ill patients with and without sepsis: multi-centered prospective observational study

Introduction

Fever is frequently observed in critically ill patients. An independent association of fever with increased mortality has been observed in non-neurological critically ill patients with mixed febrile etiology. The association of fever and antipyretics with mortality, however, may be different between infective and non-infective illness.

Methods

We designed a prospective observational study to investigate the independent association of fever and the use of antipyretic treatments with mortality in critically ill patients with and without sepsis. We included 1,425 consecutive adult critically ill patients (without neurological injury) requiring > 48 hours intensive care admitted in 25 ICUs. We recorded four-hourly body temperature and all antipyretic treatments until ICU discharge or 28 days after ICU admission, whichever occurred first. For septic and non-septic patients, we separately assessed the association of maximum body temperature during ICU stay (MAX_ICU) and the use of antipyretic treatments with 28-day mortality.

Results

We recorded body temperature 63,441 times. Antipyretic treatment was given 4,863 times to 737 patients (51.7%). We found that treatment with non-steroidal anti-inflammatory drugs (NSAIDs) or acetaminophen independently increased 28-day mortality for septic patients (adjusted odds ratio: NSAIDs: 2.61, P = 0.028, acetaminophen: 2.05, P = 0.01), but not for non-septic patients (adjusted odds ratio: NSAIDs: 0.22, P = 0.15, acetaminophen: 0.58, P = 0.63). Application of physical cooling did not associate with mortality in either group. Relative to the reference range (MAX_ICU 36.5°C to 37.4°C), MAX_ICU ≥ 39.5°C increased risk of 28-day mortality in septic patients (adjusted odds ratio 8.14, P = 0.01), but not in non-septic patients (adjusted odds ratio 0.47, P = 0.11).

Conclusions

In non-septic patients, high fever (≥ 39.5°C) independently associated with mortality, without association of administration of NSAIDs or acetaminophen with mortality. In contrast, in septic patients, administration of NSAIDs or acetaminophen independently associated with 28-day mortality, without association of fever with mortality. These findings suggest that fever and antipyretics may have different biological or clinical or both implications for patients with and without sepsis.

Trial registration

ClinicalTrials.gov: NCT00940654

Clinical implications and validity of nursing assessments: a longitudinal measure of patient condition from analysis of the Electronic Medical Record

OBJECTIVES

This study investigates risk of mortality associated with nurses' assessments of patients by physiological system. We hypothesise that nursing assessments of in-patients performed at entry correlate with in-hospital mortality, and those performed just before discharge correlate with postdischarge mortality.

DESIGN

Cohort study of in-hospital and postdischarge mortality of patients over two 1-year periods.

SETTING

An 805-bed community hospital in Sarasota, Florida, USA.

SUBJECTS

42 302 inpatients admitted for any reason, excluding obstetrics, paediatric and psychiatric patients.

OUTCOME MEASURES

All-cause mortalities and mortality OR.

RESULTS

Patients whose entry nursing assessments, other than pain, did not meet minimum standards had significantly higher in-hospital mortality than patients meeting minimums; and final nursing assessments before discharge had large OR for postdischarge mortality. In-hospital mortality OR were found to be: food, 7.0; neurological, 9.4; musculoskeletal, 6.9; safety, 5.6; psychosocial, 6.7; respiratory, 8.1; skin, 5.2; genitourinary, 3.0; gastrointestinal, 2.3; peripheral-vascular, 3.9; cardiac, 2.8; and pain, 1.1. CI at 95% are within ±20% of these values, with p<0.001 (except for pain). Similar results applied to postdischarge mortality. All results were comparable across the two 1-year periods, with 0.85 intraclass correlation coefficient.

CONCLUSIONS

Nursing assessments are strongly correlated with in-hospital and postdischarge mortality. No multivariate analysis has yet been performed, and will be the subject of a future study, thus there may be confounding factors. Nonetheless, we conclude that these assessments are clinically meaningful and valid. Nursing assessment data, which are currently unused, may allow physicians to improve patient care. The mortality OR and the dynamic nature of nursing assessments suggest that nursing assessments are sensitive indicators of a patient's condition. While these conclusions must remain qualified, pending future multivariate analyses, nursing assessment data ought to be incorporated in risk-related health research, and changes in record-keeping software are needed to make this information more accessible.