Antipyretic therapy in patients with sepsis

Fever temperatures modulate intraprotein dynamics and enhance the binding affinity between monoclonal antibodies and the Spike protein from SARS-CoV-2

Fever is a typical symptom of most infectious diseases. While prolonged fever may be clinically undesirable, mild reversible fever (<39℃, 312 K) can potentiate the immune responses against pathogens. Here, using molecular dynamics and free energy calculations, we investigated the effect of febrile temperatures (38℃ to 40℃, 311 K to 313 K) on the immune complexes formed by the SARS-CoV-2 spike protein with two neutralizing monoclonal antibodies. In analyzing the conformational dynamics of the interactions between the antibodies and the spike protein under different thermal conditions, we found that, at mild fever temperatures (311–312 K), the binding affinities of the two antibodies improve when compared to the physiological body temperature (37℃, 310 K). Furthermore, only at 312 K, antibodies exert distinct mechanical effects on the receptor binding domains of the spike protein that may hinder SARS-CoV-2 infectivity. Enhanced antibody binding affinity may thus be obtained using appropriate temperature conditions.

Modelling the Efficacy of Febrile Heating in Infected Endotherms

Fever is a response to infection characterised by an increase in body temperature. The adaptive value of this body temperature increase for endotherms is unclear, given the relatively small absolute temperature increases associated with endotherm fever, its substantial metabolic costs, and the plausibility for pathogens to adapt to higher temperatures. We consider three thermal mechanisms for fever's antimicrobial effect: (1) direct growth inhibition by elevating temperature above the pathogens optimal growth temperature; (2) further differentiating the host body from the wider environment; and (3) through increasing thermal instability of the pathogen environment. We assess these by modelling their effects pathogen on temperature dependent growth, finding thermal effects can vary from highly to minimally effective depending on pathogen species. We also find, depending on the specification of a simple physical model, intermittent heating can inhibit pathogen growth more effectively than continuous heating with an energy constraint.

Febrile temperatures increase in vitro antibody affinity for malarial and dengue antigens

Fever is a regulated increase of the body temperature resulting from both infectious and non-infectious causes. Fever is known to play a role in modulating immune responses to infection, but the potential of febrile temperatures in regulating antigen binding affinity to antibodies has not been explored. Here we investigated this process under in vitro conditions using Isothermal titration calorimetry and ELISA. We used selected malarial and dengue antigens against specific monoclonal antibodies, and observed a marked increase in the affinity of these antibody-antigen complexes at 40°C, compared to physiological (37°C) or pathophysiological temperatures (42°C). Induced thermal equilibration of the protein partners at these temperatures in vitro, prior to measurements, further increased their binding affinity. These results suggest another positive and adaptive role for fever in vivo, and highlight the favourable role of thermal priming in enhancing protein-protein affinity for samples with limited availability.

The antipyretic efficacy and safety of propacetamol compared with dexibuprofen in febrile children: a multicenter, randomized, double-blind, comparative, phase 3 clinical trial

BACKGROUND

We aimed to compare the antipyretic efficacy, safety, and tolerability between oral dexibuprofen and intravenous propacetamol in children with upper respiratory tract infection (URTI) presenting with fever.

METHODS

Patients aging from 6 months to 14 years admitted for URTI with axillary body temperature ≥ 38.0 °C were enrolled and randomized into the study or control group. Patients in the study group were intravenously infused with propacetamol and subsequently oral placebo medication was administered. Patients in the control group were intravenously infused with 100 mL of 0.9% sodium chloride solution without propacetamol and then oral dexibuprofen was administered. We checked the body temperature of all patients at 0.5 h (hr), 1 h, 1.5 h, 2 h, 3 h, 4 h, and 6 h after oral placebo or dexibuprofen had been applied.

RESULTS

A total of 263 patients (125 in the study group) were finally enrolled. The body temperatures of patients in the study group were significantly lower until 2 h after administration (37.73 ± 0.58 vs 38.36 ± 0.69 °C (p < 0.001), 37.37 ± 0.53 vs 37.88 ± 0.69 °C (p < 0.001), 37.27 ± 0.60 vs 37.62 ± 0.66 °C (p < 0.001), 37.25 ± 0.62 vs 37.40 ± 0.60 °C (p = 0.0452), at 0.5 h, 1 h, 1.5 h, and 2 h, respectively). The two groups showed no significant differences in terms of the range of body temperature decrease, the Area Under the Curve of body temperature change for antipyretic administration-and-time relationship, the maximum value of body temperature decrease during the 6 h test period, the number of patients whose body temperature normalized (< 37.0 °C), the mean time when first normalization of body temperature, and the development of adverse events including gastrointestinal problem, elevated liver enzyme, and thrombocytopenia.

CONCLUSIONS

Intravenous propacetamol may be a safe and effective choice for pediatric URTI patients presenting with fever who are not able to take oral medications or need faster fever control.

TRIAL REGISTRATION

CRIS KCT0002888 . Date of registration: July 31st, 2013.

Similar but not the same: Differential diagnosis of HLH and sepsis. Crit Rev Oncol Hematol. 2017;114:1-12. [PMID: 28477737 DOI: 10.1016/j.critrevonc.2017.03.023]

Differential diagnosis of hemophagocytic lymphohistiocytosis (HLH; hemophagocytic syndrome) and sepsis is critically important because the life-saving aggressive immunosuppressive treatment, required in the effective HLH therapy, is absent in sepsis guidelines. Moreover, HLH may be complicated by sepsis. Hyperinflammation, present in both states, gives an overlapping clinical picture including fever and performance status deterioration. The aim of this review is to provide aid in this challenging diagnostic process. Analysis of clinical features and laboratory results in multiple groups of patients (both adult and pediatric) with either HLH or sepsis allows to propose criteria differentiating these two conditions. The diagnosis of HLH is supported by hyperferritinemia, splenomegaly, marked cytopenias, hypofibrinogenemia, low CRP, characteristic cytokine profile and, only in adults, hypertriglyceridemia. In the presence of these parameters (especially the most characteristic hyperferritinemia), the other HLH criteria should be assessed. Genetic analyses can reveal familial HLH. Hemophagocytosis is neither specific nor sensitive for HLH.

Outcome of severe infections in afebrile neutropenic cancer patients

BACKGROUND

In some neutropenic cancer patients fever may be absent despite microbiologically and/or clinically confirmed infection. We hypothesized that afebrile neutropenic cancer patients with severe infections have worse outcome as compared to cancer patients with febrile neutropenia.

PATIENTS AND METHODS

We retrospectively analyzed all adult cancer patients with chemotherapy-induced neutropenia and severe infection, who were admitted to the Intensive Care Unit at our cancer center between 2000 and 2011. The outcome of interest was 30-day in-hospital mortality rate. Association between the febrile status and in-hospital mortality rate was evaluated by the Fisher's exact test.

RESULTS

We identified 69 episodes of severe neutropenic infections in 65 cancer patients. Among these, 9 (13%) episodes were afebrile. Patients with afebrile neutropenic infection presented with hypotension, severe fatigue with inappetence, shaking chills, altered mental state or cough and all of them eventually deteriorated to severe sepsis or septic shock. Overall 30-day in-hospital mortality rate was 55.1%. Patients with afebrile neutropenic infection had a trend for a higher 30-day in-hospital mortality rate as compared to patients with febrile neutropenic infection (78% vs. 52%, p = 0.17).

CONCLUSIONS

Afebrile cancer patients with chemotherapy-induced neutropenia and severe infections might have worse outcome as compared to cancer patients with febrile neutropenia. Patients should be informed that severe neutropenic infection without fever can occasionally occur during cancer treatment with chemotherapy.

Why Fever Phobia Is Still Common?

Background

Fever is a reliable sign of illness, but it also evokes fear and anxiety. It is not the fever itself but the fear of possible complications and accompanying symptoms that is important for pediatricians and parents.

Objectives

We aimed to investigate maternal understanding of fever, its potential consequences, and impacts on the treatment of children.

Patients and Methods

A questionnaire was use to explore the attitudes, knowledge, and practices of mothers of 861 children brought to four medical centers in different regions of Turkey in 2012, with fever being the chief complaint. All the children were aged 3 months - 15 years.

Results

Among the 861 mothers, 92.2% favored antipyretics for fever, either alone or in addition to external cooling measures. Most favored paracetamol or ibuprofen. In this study, the appropriate use of antipyretics was 75.2%, which was higher than that reported in the literature. In common with previous reports, seizures and brain damage were perceived as the most frightening and harmful effects of fever. All the mothers expressed concerns about fever, but they were most common among the highly educated or those with one child.

Conclusions

Fever phobia remains common, not only among low socioeconomic status mothers but also among those of high socioeconomic status. Healthcare providers should take fever phobia into account and provide correct information to caregivers about fever at all visits.

Fever literacy and fever phobia

OBJECTIVE

To identify the percentage of parents who define the threshold for fever between 38.0°C and 38.3°C, which has not been reported previously, and to describe parental attitudes toward fever and antipyretic use.

STUDY DESIGN

Thirteen-question survey study of caregivers.

RESULTS

Overall, 81% of participants defined the threshold for fever as <38.0°C, 0% correctly defined fever between 38.0°C and 38.3°C, and 19% defined fever as >38.3°C. Twenty percent of children brought to clinic for a chief complaint of fever were never truly febrile. Ninety-three percent of participants believed that high fever can cause brain damage. For a comfortable-appearing child with fever, 89% of caregivers reported that they would give antipyretics and 86% would schedule a clinic visit.

CONCLUSION

Our finding that 0% of parents correctly defined fever is both surprising and unsettling, and it should inform future discussions of fever between parents and clinicians.

The continuing question of how fever duration is associated with patient outcome

Although fever magnitude and etiology have been associated with outcomes of critically ill patients, possible associations between fever duration and mortality remain inconclusive. Since long-lasting fever is generally attributed to severe pathologic conditions, it is expected to be an indicator of adverse outcome. It also seems plausible that persistent fever in specific patient groups, mainly those with cerebral damage or limited cardiorespiratory reserve, could lead to worsened outcomes. Existing studies on these associations have been considerably limited because of methodological flaws, which may account for controversial findings that have been reported. Well-designed, large-sample studies using diverse measures of fever duration need to be conducted.

Randomized trial of the effect of intravenous paracetamol on inflammatory biomarkers and outcome in febrile critically ill adults

Background and the purpose of the study

The febrile reaction is a complex response involving immunologic and other physiologic systems. Antipyretics are commonly used in critically ill patients with fever. We investigated the inflammatory responses following application of antipyretic therapy in febrile critically ill patients with Systemic Inflammatory Response Syndrome (SIRS).

Patients and methods

In a prospective, randomized controlled study, critically ill patients with fever (T ≥ 38.3°C), SIRS diagnosed within 24 hours of Intensive Care Unit (ICU) admission and Acute Physiology and Chronic Health Evaluation II (APACHE II) score ≥10 were randomized into two groups. Upon appearance of fever, one group received intravenous paracetamol 650 mg every 6 hours for 10 days and other group received no treatment unless temperature reached 40°C. Body temperature, Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sepsis-related Organ Failure Assessment (SOFA) scores, length of ICU stay, ICU mortality and infectious complications were recorded. Levels of Interleukin-1 alpha (IL-1_α), IL-6, IL-10, Tumour Necrosis Factor alpha (TNF_α) and High-Sensitive C-Reactive Protein (HS-CRP) were assessed at baseline and 2, 6 and 24 hours after intervention.

Results and discussion

During a period of 15-month screening, 20 patients met the criteria and randomized to the control or paracetamol group. Body temperature decreased significantly in the paracetamol group (p = 0.004) and control group (p = 0.001) after 24 hours, but there was no significant difference between two groups at this time point (p = 0.649). Levels of IL-6 and IL-10 decreased significantly (p = 0.025 and p = 0.047, respectively) in the paracetamol group at 24 hours but this was not of statistical significance in control group. No patterns over time in each group or differences across two groups were found for HS-CRP, TNF_α, and IL-1_α (p > 0.05). There were no differences regarding ICU length of stay, mortality and infectious complications between both groups.

Conclusion

These results suggest that antipyretic therapy may not be indicated in all ICU patients. Allowing fever to take its natural course does not appear to have detrimental effects on critically ill patients with SIRS and may avoid unnecessary expenses.

Fever and antipyretic use in children

Fever in a child is one of the most common clinical symptoms managed by pediatricians and other health care providers and a frequent cause of parental concern. Many parents administer antipyretics even when there is minimal or no fever, because they are concerned that the child must maintain a "normal" temperature. Fever, however, is not the primary illness but is a physiologic mechanism that has beneficial effects in fighting infection. There is no evidence that fever itself worsens the course of an illness or that it causes long-term neurologic complications. Thus, the primary goal of treating the febrile child should be to improve the child's overall comfort rather than focus on the normalization of body temperature. When counseling the parents or caregivers of a febrile child, the general well-being of the child, the importance of monitoring activity, observing for signs of serious illness, encouraging appropriate fluid intake, and the safe storage of antipyretics should be emphasized. Current evidence suggests that there is no substantial difference in the safety and effectiveness of acetaminophen and ibuprofen in the care of a generally healthy child with fever. There is evidence that combining these 2 products is more effective than the use of a single agent alone; however, there are concerns that combined treatment may be more complicated and contribute to the unsafe use of these drugs. Pediatricians should also promote patient safety by advocating for simplified formulations, dosing instructions, and dosing devices.

Article Commentary: Optimizing Surgical Care: A Contemporary Assessment of Temperature, Oxygen, and Glucose

Factors such as temperature, oxygen, and glucose have recently been implicated in the development of surgical sepsis by either promoting or attenuating protective components of the innate immune response. Reducing infective sequelae and the improvement of the quality of care of surgical patients is a top practice priority today. These factors and their associated effects are discussed through the examination of recent clinical and scientific studies to provide an up-to-date evidence-based review.

Immunological role of neuronal receptor vanilloid receptor 1 expressed on dendritic cells

Capsaicin (CP), the pungent component of chili pepper, acts on sensory neurons to convey the sensation of pain. The CP receptor, vanilloid receptor 1 (VR1), has been shown to be highly expressed by nociceptive neurons in dorsal root and trigeminal ganglia. We demonstrate here that the dendritic cell (DC), a key cell type of the vertebrate immune system, expresses VR1. Engagement of VR1 on immature DCs such as by treatment with CP leads to maturation of DCs as measured by up-regulation of antigen-presenting and costimulatory molecules. This effect is present in DCs of VR1+/+ but not VR1-/- mice. In VR1+/+ mice, this effect is inhibited by the VR1 antagonist capsazepine. Further, intradermal administration of CP leads to migration of DCs to the draining lymph nodes in VR1+/+ but not VR1-/- mice. These data demonstrate a powerful influence of a neuroactive ligand on a central aspect of immune function and a commonality of mechanistic pathways between neural and immune functions.

The Effects of Drugs on Thermoregulation

Body temperature is a balance of the hypothalamic set point, neurotransmitter action, generation of body heat, and dissipation of heat. Drugs affect body temperature by different mechanisms. Antipyretics lower body temperature when the body's thermoregulatory set point has been raised by endogenous or exogenous pyrogens. The use of antipyretics may be unnecessary or may interfere with the body's resistance to infection, mask an important sign of illness, or cause adverse drug effects. Drugs may cause increased body temperature in five ways: altered thermoregulatory mechanisms, drug administration-related fever, fever from the pharmacologic action of the drug, idiosyncratic reactions, and hypersensitivity reactions. Certain drugs cause hypothermia by depression of the thermoregulatory set point or prevention of heat conservation. By affecting the balance of thermoregulatory neurotransmitters, drugs may prevent the signs and symptoms of hot flashes.

Double blind comparison of ibuprofen and paracetamol for adjunctive treatment of uncomplicated typhoid fever

BACKGROUND

Antipyretics reduce the prolonged, high fever characteristic of typhoid fever. The benefits of nonsteroidal drugs in this role have not been quantified. There have been concerns about the safety of antipyretics in typhoid.

METHODS

In a double blind randomized study, 80 Vietnamese children with uncomplicated typhoid fever were randomized to receive identical syrup preparations of ibuprofen (10 mg/kg) or paracetamol (12 mg/kg) every 6 h until 36 h after defervescence. Children with a nalidixic acid-susceptible (Na) isolate of Salmonella typhi were treated with ofloxacin (15 mg/kg/day) for 3 days and those with a nalidixic acid-resistant (Na) isolate were treated for 7 days.

RESULTS

S. typhi was isolated from 36 of 40 children randomized to ibuprofen (11 isolates Na) and 37 of 40 randomized to paracetamol (13 isolates Na). The median (range) fever clearance time (hours) was shorter in the ibuprofen group than the paracetamol group (68, 4 to 260 vs. 104, 12 to 404; P = 0.055) as was the area under the temperature time curve above 37 degree C (74, 0 to 237 vs. 127, 0 to 573; P = 0.013). The differences occurred predominantly in the children infected with a NaS. typhi whose infections responded more slowly to antibiotic treatment. There were no major side effects associated with the use of either drug. There were no differences between the two treatment arms in the concentrations of circulating interleukin-6 and tumor necrosis factor alpha during the course of treatment.

CONCLUSION

The antipyretic effect of ibuprofen is superior to that of paracetamol in children with typhoid fever, particularly those with prolonged fever. Both antipyretics appeared to be safe.

Fever: beneficial and detrimental effects of antipyretics

Although various forms of therapy have been used, since antiquity, to lower the temperature of febrile patients, it is still not known whether the benefits of antipyretic therapy outweigh its risks. Justifications for the use of antipyretic drugs, and the evidence pertaining to these rationales, are examined. Antipyretic therapy in sepsis, and adverse effects of antipyretic medications, are also reviewed.