Background:
Hypothermia is defined as core body
temperature < 36ËšC(Normal body
temperature: 36.5°C to 37.5°C).Hypothermia can be further classified as
mild (when body temperature is 35.0-36°C, moderate (when body temperature is
33-34.9°C and severe (when body temperature is <33°C. During surgery
hypothermia can result due to heat loss from the patient’s body either by conduction, radiation, convection or
evaporation. Conduction is the physical transmission of heat from the patient
to another item, like a bed or theatre table. Radiation is the heat that a
patient’s metabolism produces and emits. Convection is the process by which air
travels about the patient to dissipate heat. Evaporation, which happens
continuously as the patient breathes. Exposure to the cold operating room and
evaporative losses further exacerbate the issue as anaesthesia affects the
body’s ability to regulate its internal temperature, causing core-heat
redistribution and heat loss to the environment.
Hypothermia during surgery causes many
pathophysiological changes.The circulatory, adrenergic, and respiratory systems are all affected by
prolonged hypothermia. Moderate hypothermia even delays the time it takes to
recover from anaesthesia and the metabolism of anaesthetics and neuromuscular
blocking drugs resulting in unplanned postoperative ventilation. Ventricular
dysrhythmias are more likely when the sympathetic nervous system is stimulated
in response to cold and when serum potassium levels change. Additionally,
hypothermia changes the coagulation cascade and platelet function, increasing
bleeding. Vasoconstriction-induced tissue hypoxia can cause a wound to take
longer to heal. Also patients are more vulnerable to developing an infection at
the surgical site because hypothermia inhibits neutrophil activity and reduces
the effectiveness of macrophages and lymphocytes.
Infants and children are at a greater
risk to develop hypothermia as they have less effective regulatory capacity,
limited subcutaneous fat stores and differences in body size. Few studies have
reported 4.5%-50% incidence of perioperative hypothermia in children. Reports
of pediatric outcomes resulting from perioperative hypothermia are limited.
Peri-operative hypothermia is a silent
and often missed factor which may contribute to adverse post operative outcomes
like delay in surgical site wound healing, increased risk of wound infection,
delayed recovery, prolonged ICU or hospital stay and increased mortality.Therefore,
perioperative temperature monitoring and use of various measures (cutaneous
warming systems like under surface warming mattress and warming blankets and
fluid warming devices) to avoid intraoperative hypothermia are important
quality improvement measures aimed to optimize surgical care and improve
perioperative outcomes. Study Design: This study is a prospective observational study
as a part of dissertation in Tata Memorial Hospital for the period of 1 year.
This study will be carried out after obtaining approval from the Institutional
Ethics committee and CTRI registration Study
methodology: Data will be collected from all eligible
patients. All children will receive anaesthesia according to the current
standard of care. All children coming for surgery are premedicated and taken in
the OT. The OT table is pre warmed with a warming blanket before taking the
patient in. Standard monitors (Electrocardiogram, noninvasive blood pressure
and pulse oximetry) are attached according to the ASA guidelines. After
induction of anesthesia temperature monitoring will be done with either an
esophageal or surface temperature probe. The need for invasive blood pressure
monitoring and regional anaesthesia techniques for pain management will be
decided by the anaesthesiologist conducting the case.Forced air warming
blankets and fluid warmers will be used to prevent intraoperative hypothermia.
This is our current standard of care and no additional interventions will be
done for the purpose of the study. We are just auditing our current practice of
perioperative temperature regulation. Data will be collected from the electronic
records of all the children undergoing elective surgery at Tata Memorial
Centre. The following data will be collected Demographic data ·
Age
and gender ·
Height
weight and BMI Intra - operative information - Type of
anaesthesia: General anaesthesia(GA) / Regional anaesthesia (RA) / GA+RA. - Temperature
monitoring method – Core temperature/Surface temperature - Method of active
warming used – fluid warmers, warming blankets, other measures - Temperature at
the start and end of anaesthesia - Hourly
temperature recorded for the duration of surgery - Minimum and
maximum intra-operative temperature - Duration of
hypothermia - Need to stop
active warming - Intraoperative
blood loss - Intraoperative complications
– arrhythmia, bleeding, hypotension needing vasopressors - Details of
surgery o
Grade
of surgery- Minor /Intermediate/Major o
Site
of surgery – Cavity surgery / surface surgery - Duration of
surgery and anaesthesia Post-operative information - Post op core
temperature - Need for active
warming device - Unplanned mechanical
ventilation - Delay recovery - Complications
according to Clavien Dindo classification - ICU stay - Hospital stay All patients
included in the study will be followed up by the study team till discharge from
the hospital.No biological samples will be taken from the patient. No
additional hospital visits will be required.There are no stop points or
withdrawal criteria. Statistical Analysis: Categorical
variables will be expressed as percentages. Data for continuous variables will
be expressed as mean (SD) with range (minimum ± maximum values). Univariate and
multivariate logistic regression analysis will be done to see if there is any
association between intraoperative hypothermia and age, BMI, duration of
surgery, grade of surgery, site of surgery, warming measures, blood loss and intraoperative
complications. Data will be presented as mean value + SD unless otherwise
indicated and P < 0.05 will be considered significant. Analysis will be done
using SPSS version 25 (IBM Corp. Released in 2017. IBM SPSS Statistics for
Windows, Version 25).
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