Magnitude and associated factors of intra-operative hypothermia among pediatric patients undergoing elective surgery: A multi-center cross-sectional study

Background Hypothermia is a core body temperature of less than 36 c0 that could increase perioperative morbidity & mortality of pediatric patients operated under general anesthesia. This study aimed to assess the magnitude and associated factors of intra-operative hypothermia among pediatric patients undergoing elective surgery. Method Institutional based cross-sectional study was conducted on 339 pediatric patients undergoing elective surgery in referral hospitals of Addis Ababa, Ethiopia. Data were collected using a structured questionnaire. Descriptive statics were expressed in percentage and presented with tables. Both Bivariable and multivariable logistic analysis was done to identify factors associated with intra-operative hypothermia among pediatric patients undergoing elective surgery. P < 0.05 with 95% CI was set as statistical significance. Result The magnitude of intra-operative hypothermia in this study was 39.8 [95% CI= (34.5–45.1)]. Multivariable logistic analyses showed that ambient temperature less than 26c0 [AOR = 6; 95%CI=(2.859–13.23)], volume of fluid administered greater than half a liter [AOR = 3.6; 95%CI=(1.83–7.23)], Patients who were received un-warm fluid [AOR = 2.2; 95%CI=(1.28–4.04)] and duration of surgery and anesthesia greater than 120 min [AOR = 3.4; 95%CI=(1.29–8.79)] and [AOR = 3.8; 95%CI=(1.25–11.53)] respectively were factors significantly associated with intra-operative hypothermia. Conclusion The magnitude of intra-operative hypothermia in this study was high. So, adherence must be done in the prevention of intraoperative hypothermia by health professionals such as increasing operation room temperature, warming administered fluid, optimal fluid administration, and reduction of the duration of surgery and anesthesia.


Introduction
Hypothermia is a core body temperature of less than 36c 0 frequently encountered in pediatric patients operated under general anesthesia [1,2]. Maintaining normothermia is vital for patient comfort and the prevention of complications caused by hypothermia [3][4][5].
Intraoperative hypothermia during surgery and anesthesia affects more than 70% of patients during surgery and anesthesia. The incidence of intraoperative hypothermia in pediatric patients is higher than preoperative and postoperative hypothermia [6][7][8].
Pediatric patients are at high risk of hypothermia due to easy heat loss caused by higher surface area to volume ratio, immature hypothalamic thermoregulatory capacity, and less insulating subcutaneous tissue [11][12][13]. Also, impairment of the non-shivering thermogenesis mechanism of brown fat for heat production during general anesthesia plays a great role in hypothermia [14][15][16][17].
Despite evidence is limited regarding the magnitude and associated factors of intraoperative hypothermia in the pediatric age group in the study areas. So, this study is important to prevent and manage intraoperative hypothermia in pediatrics patients undergoing general surgery.

Methods and materials
This cross-sectional study was conducted in the capital city, Addis Ababa, Ethiopia in public referral hospitals. The altitude of the city ranges from 2200 to 3000 m above sea level with an average temperature of 22

Inclusion and exclusion criteria
Pediatric patients who were less than 18 years old were included in the study. While procedures with anesthesia duration less than 30 min, patients who have sustained one or more traumatic injuries, Patients with body temperature greater than 38 0c and less than 36 0c , patients who underwent open-heart surgery, and a patient who refused were excluded from the study.

Sample size
The sample size was determined by using single proportion formula considering the following assumptions: 95% confidence interval (Z α/2 ), 5% margin of error(d), 30% incidence of intraoperative hypothermia(P) [23], and considering 5% non-response rate, finally, 339 sample size was obtained.

Sampling technique and procedure
A systematic random sampling technique was used to get the study participants. The total numbers of pediatrics patients included in the study were propotionated depending on the number of three-month elective surgeries done in each referral Hospital, using a formula nj= (n/N)Nj. Also, study participants from each hospital were selected using the systematic random sampling technique on daily operation schedule lists. Depending on situational analysis of 3 months, an average of 500 patients were operated. Then sampling interval (K) was determined using the formula: K--N/n; 500/339 = 1.47 ≈ 2 Where, n = total sample size, N = population per 3 months. Taking sampling interval two, the first study participant (random start) was selected using the lottery method from the daily surgery list.

Data collection instrument and procedures
Data was collected by using an English version structured questionnaire taken from studies. The temperature of patients was measured intraoperative using a digital axillary thermometer with an accuracy of ± 0.1 c o by placing the probe in the armpit close to the axillary artery by tightly adducting the arm. Intraoperative body temperature was taken after surgery before the extubation of the patient. The ambient temperature was also recorded after the patient enters in operation room by using a digital room thermometer after providing training for data collectors and having verbal informed consent taken from their parent's data was collected using a questionnaire. The data was collected by four trained anesthetists; one data collector for each hospital after informed consent was taken from parents.

Data quality assurance
After training was given to data collectors, data were collected and properly filled in the prepared format. The supervision was made throughout the data collection period to make sure the accuracy, clarity, and consistency of the collected data. A pre-test was done on 5% of the sample size from Yikatit 12 referral hospital.

Ethical consideration
The ethical clearance to conduct the study was obtained from Addis Ababa University institutional review board and an Official support letter was given from referral hospitals of Addis Ababa as well informed written consent was secured from each study participant's family. Confidentiality was assured throughout the research.

Data entry, analysis, and interpretation
The collected data were coded, entered, and analyzed using SPSS version 26. Descriptive statistics were carried out and expressed in text, tables, and figures, and both bi-variable and multivariable logistic regression analyses were used to identify factors associated with the intraoperative hypothermia of patients undergoing elective surgery. Variables with a p-value of less than <0.2 in the bivariable logistic analysis were fitted into a multivariable logistic regression analysis. Both crude odds ratio (COR) in bivariable logistic regression and adjusted odds ratio (AOR) in multivariable logistic regression with the corresponding 95% confidence interval were calculated to show the strength of association. In multivariable logistic regression analysis, variables with a p-value <0.05 were considered statistically significant.
Pediatric patient: a patient whose age is less than 18 years old [26].

Socio-demographic characteristics of study participants
A sample of 339 study participants was involved in this study with a full response rate. The majority of participants in this study were males 207 (61.1%). The weight of study participants with Mean ± SD was 13.58 ± 8.4 kg.

Anesthetic and surgical characteristics of study participants
Gastrointestinal surgery 82 (24.2%) was done in the majority of study participants while 237 (69.9%) were done under general anesthesia without any combined regional techniques. The Mean ± SD operation room temperature was 24.28 ± 2. The majority of patients were done with an operation room temperature of less than 26 c o , 247 (72.9%). Duration surgery and anesthesia were 126.6 ± 29.3 min and 139.7 ± 31.5 min respectively (Table-2).

Magnitude of intra-operative hypothermia
In this study, the magnitude of intra-operative hypothermia of pediatric patients undergoing elective surgery with general anesthesia was 39.8% [95% CI= (34.5-45.1)].

Factor associated with intra-operative hypothermia
The bivariable logistic analyses showed that Age, ASA PS, room temperature, un-warm fluid administered, the volume of fluid administered, duration of surgery, and anesthesia were factors associated with intra-operative hypothermia. Also, in multivariable logistic recreation neonates [AOR = 15; 95%CI=(2.256-101.8)], and infant age groups [AOR = 8.4; 95%CI=(1.548,45.86)] were more likely to develop intra-operative hypothermia than adolescents. Patients who have done surgery and anesthesia at an ambient temperature of less than 26c 0 were [AOR = 6; 95%CI=(2.859-13.231)] more likely to develop interoperative hypothermia than those who underwent surgery with room temperature greater than 26c o .

Discussion
This study reviled that magnitude of intra-operative hypothermia was 39.8% indicating a higher magnitude. This finding is higher than a study done in Kenya 30% [23]. These variations could be due to differences in the technique of measurement and may be due to differences in sample size. While this result was lower than a study done in the United State of America 52% [27] and Uganda 71.7% [28]. This possible reason could be due to variations in clinical setups, population, and seasonal variation.
In this study neonates [AOR = 15; 95%CI=(2.256-101.8)] and infants [AOR = 8.4; 95%CI= (1.548-45.86)] were statistically significant associated with intra-operative hypothermia. This result was consistent with a study done in Malaysia [26]. This might be due to undeveloped physiological thermoregulation mechanism, less subcutaneous tissue, and high body surface area to volume ratio contribute for hypothermia.
Room temperature less than 26c o [AOR; 6, (95%CI, 2.859, 13.231)] was significantly associated with intra-operative hypothermia. This result was similar to a study done in India [8]. Also, Patients who received un-warm fluid [AOR, 2.2, (95%CI, 1.28, 4.05)] during intra-operative were significantly associated with intra-operative hypothermia. This result is consistent with a study conducted in 2011 in the USA that showed, pre-warming administer fluids and other materials reduce intra-operative hypothermia [12].
In this study administration of greater than 1 L of fluid was significantly associated with intra-operative hypothermia. This was similar to a study conducted in Turkey . [1]. The possible reason could be due to redistribution of a high volume of fluid to the system and results reduction of heat.
In this study pediatric patients with a duration of surgery greater than 120 min [AOR; 3.4, (95%CI, 1.297, 8.797)] and duration of anesthesia greater than 120 min [(AOR; 3.8, (95%CI; 1.25, 11.53)] were significantly associated with intra-operative hypothermia. This study was similar to a study conducted USA and Brazile [11,29]. This might be due to suppuration of the thermoregulatory center by anesthetic agents, prolonged heat loss, and increased intravenous fluid administration to replace the fluid. So, surgeons, anesthetists, and nurses should take great responsibility in the reduction of factors causing intraoperative hypothermia in pediatrics patients.

Conclusion
The magnitude of intra-operative hypothermia in this study was high. So, adherence must be done in the prevention of intraoperative hypothermia by health professionals such as increasing operation room temperature, warming administered fluid, optimal fluid administration,  and reduction of the duration of surgery and anesthesia.

Limitation of study
The limitations of this study were, the first use of a digital axillary thermometer us a measurement of core body temperature may lead to measurement errors, second, blinding was not applied, third a broad range of age group from neonates to adolescents' might affect the outcome, and fourthly high percentage of infant and toddlers patients might affect the strength of the study.

Ethics approval and consent
Ethical clearance was obtained from Addis Ababa University institutional review board and an Official support letter was given from referral hospitals of Addis Ababa as well informed written consent was secured from each study participant's family. Confidentiality was assured throughout the research.

Funding
Not funded. the referral hospitals of Addis Ababa administrators for accepting to conduct the study as well special thanks to families of pediatrics patients for accepting and taking consent to conduct this study.