A Novel Device for Intraoperative Hypothermia Prevention in Patients with Lower Abdominal Surgery: A Prospective Randomized Single-Center Study

Abstract

This study aims to explore the value of lithotomy position thermal sleeve application during lower abdominal surgery in patients with hypothermia. A total of 100 patients who underwent urinary, gastrointestinal, or gynecological operations were included in this study. The patients were randomly divided into two groups: the test group (n = 50) and the control group (n = 50). In the control group, the environment, fluid, patient upper abdomen, and pasted 3 L stone-cut pants were heated. In the test group, the lithotomy position surgical warmer was used based on environment, fluid, and upper abdomen warming. The various indicators present in the two groups were compared and analyzed using the Statistical Package for Social Sciences 19.0. Before the operation, the body temperature was 36.73°C ± 0.28°C in the test group and 36.74°C ± 0.29°C in the control group; the difference between the two groups was not statistically significant (p > 0.05). In the test group, the entry temperature was 36.83°C ± 0.04°C; after 2 hours of operation, it became 37.21°C ± 0.03°C. There were no significant changes in body temperature after 4 hours of operation, basic body temperature was maintained (36.80°C ± 0.02°C). In the control group, the entry temperature was 36.54°C ± 0.05°C; however, it became 35.94°C ± 0.07°C after 2 hours of operation, making the patient prone to developing hypothermia. The differences between the two groups were statistically significant (p < 0.05). In patients undergoing urinary, anorectal, or gynecological operations, the use of a warming intervention during surgery in the lithotomy position can effectively stabilize body temperature and reduce the occurrence of postoperative shivering. ClinicalTrials.gov ID: ChiCTR2100046522.

Background

Intraoperative hypothermia is a common complication of anesthesia and surgery. A body temperature of <36°C at any time during surgery is referred to as intraoperative hypothermia (Wittenborn et al., 2019), which is more concerned by nurses in operating room. Although intraoperative hypothermia can reduce organic metabolism and oxygen consumption as well as increase tissue and organ tolerance of ischemia and hypoxia, it can also cause a variety of complications, affecting surgical safety of the patient (Sandoval et al., 2017) and easily causing surgical site infection (Hassani et al., 2018).

Increased lower limb area exposure, an expanded disinfection range, and a large amount of saline flushing during surgery in the lithotomy position increase the risk of intraoperative hypothermia (Chen et al., 2019). With an operation time of >2 hours (Park et al., 2017), the postoperative hypothermia and postoperative shivering occurrence rate increases. A low temperature of the lower limbs can also cause problems, such as poor blood circulation, numbness, and dullness, prolonging patient adjustment response time.

Xu et al. (2019) and Pereira and Mattia (2019) guidelines strongly recommend mandatory air heating device use to keep the patient's temperature at ≥36.5°C from the beginning of anesthesia induction. Previous studies have shown that the effectiveness of preventive measures is crucial (Shaw et al., 2017) and that limb heating is more effective than trunk heating among all kinds of insulation measures (Romero et al., 2016). However, there is currently no good method for insulating lower limbs in patients requiring surgery in the lithotomy position.

We have developed a type of disposable thermal sleeve for surgery in the lithotomy position to keep patients' lower limbs warm. A double-layer insulation measure for lower limbs was designed based on 3 L disposable pasted surgical pants. The sleeve's outer air intake layer is made of polyethylene film that is a medical pressure-sensitive adhesive, single and thin paper with waterproofing and isolation functions, and the inner air outlet layer is made of cotton fabric. Furthermore, the double layer can be inflated and heated. This study was aimed to investigate the effect of the sleeve on the occurrence of postoperative shivering as well as the incidence of intraoperative hypothermia in patients undergoing abdominal surgery.

Materials and Methods

Patients

A total of 100 patients who received lithotomy in the urology, gynecology, or gastroenterology departments of our hospital between June 2019 and June 2020 and met the inclusion criteria were enrolled in this study. The patients were randomly divided into two groups: the test group (n = 50) and the control group (n = 50). A different hypothermia prevention method was applied in each group.

Inclusion criteria were (1) patients who provided written informed consent before enrolment, (2) patients aged 25–65 years, (3) patients with an American Society of Anesthesiology (ASA) grade of I–II, (4) patients undergoing abdominal surgery in the lithotomy position, and (5) patients with a preoperative temperature within the normal range.

Each group included 25 male and 25 female patients. The anesthesia methods used were intravenous inhalation and general compound anesthesia. There were no statistically significant differences in age, gender, ASA grade, and other indicators between the two groups (p > 0.05).

Study design

Control group

Conventional intraoperative insulation measures were used in the control group to keep patients warm. The operating room ambient temperature was 21–25°C, and quilts were covered to stay warm before and after the operation. The stored blood and liquid were heated before infusion, the abdominal cavity was rinsed with warm saline at 37–40°C, and the 3 M heating blanket temperature was adjusted to ∼40°C. The patient's nasopharyngeal temperature was recorded before the operation, every 0.5 hours during the operation, and every 1 hour until 4 hours after the operation.

Test group

In addition to the conventional intraoperative insulation measures, a thermal sleeve for surgery in the lithotomy position was used in the lower extremities in the test group. The patient's nasopharyngeal temperature was recorded before the operation, every 0.5 hours during the operation, and every 1 hour until 4 hours after the operation.

Observational indicators

Patient body temperature was recorded at each already listed time point during the operation in the two groups. In the control group, the environment, fluid, and upper abdomen were heated, and 3 L stone-cutting pants were applied. A thermal sleeve for surgery in the lithotomy position was applied in the test group based on the environment, fluid, and upper abdomen heating. The effect of the thermal sleeve on preventing intraoperative hypothermia was evaluated by comparing the core temperature and the postoperative shivering incidence in the two groups.

Result

There was no significant difference in clinical data between the two groups (Table 1). The hypothermia (Table 2) and postoperative shivering (Table 3) incidences were measured at 0.5, 1, 1.5, and 2 hours during the operation and at 1, 2, 3, and 4 hours after the operation. The results showed that, in the test group, the patient's temperature was kept at a stable level almost the entire time during the operation without obvious change, achieving the sleeve's purpose of intraoperative hypothermia prevention. However, in the control group, the patient's temperature decreased significantly 2 hours after the operation. Furthermore, the patients were prone to hypothermia, and the postoperative shivering incidence reached 16%, affecting patient comfort.

Table 1.

Comparison of Clinical Data Between the Two Groups

Group	No. of cases	Age (years)	Body mass index	Time of operation	Intraoperative temperature	Intraoperative fluid volume
Control group	50	43.25 ± 12.36	23.01 ± 3.66	187.42 ± 50.39	22.13 ± 0.20	1310 ± 180
Test group	50	45.38 ± 10.75	22.88 ± 3.76	183.55 ± 56.34	22.04 ± 0.31	1264 ± 210
t		0.9195	0.8613	0.362	1.725	1.176
p		0.3601 (>0.05)	0.1752 (>0.05)	0.7181 (>0.05)	0.877 (>0.05)	0.2424 (>0.05)

Table 2.

Comparison of Nasopharyngeal Temperature at Different Time Points During Perioperative Period Between the Two Groups

	Control group	Test group	t	p
No. of cases	50	50
Preanesthesia	36.74 ± 0.29	36.73 ± 0.28	0.1754	0.8611
0.5 hour during the operation	36.54 ± 0.05	36.83 ± 0.04	4.531	0.0001
1 hour during the operation	36.36 ± 0.05	37.00 ± 0.04	10.59	0.0001
1.5 hours during the operation	36.11 ± 0.06	37.13 ± 0.04	14.39	0.0001
2 hours during the operation	35.94 ± 0.07	37.21 ± 0.03	16.18	0.0001
1 hour after the operation	36.06 ± 0.06	37.08 ± 0.03	15.77	0.0001
2 hours after the operation	36.22 ± 0.06	36.98 ± 0.03	12.28	0.0001
3 hours after the operation	36.41 ± 0.05	36.88 ± 0.03	8.161	0.0001
4 hours after the operation	36.56 ± 0.05	36.80 ± 0.03	4.505	0.0001

Table 3.

Comparison of Postoperative Shivering Between the Two Groups

Group	No. of cases	Shiver
Control group		No. of cases occurred	Occurrence rate%
Test group	50	8	16
	50	0	0

Discussion

Intraoperative hypothermia is a preventable complication associated with more postoperative shivering, and longer hospital stays. Jin et al. have reported that, in China, the intraoperative hypothermia occurred as high as 44.3% (PMID: 28594825). Intraoperative hypothermia also inhibits the anesthetic drug metabolism, slows down the blood flow rate, increases blood viscosity, and prolongs anesthesia extubation time. A long operation time and use of a large amount of flushing fluid will cause hypothermia, leading to heat emission and resulting in postoperative shivering, limb coldness, and reaction dullness.

It is well known that core heat loss caused by postanesthetic thermal gravimetric distribution can be minimized (Allene, 2020). Effective intraoperative insulation measures are the most potent nondrug method for intraoperative hypothermia prevention (Jin and Sheng, 2018).

In this study, we found that strengthening lower limb insulation can reduce heat emission of exposed skin, promote blood circulation, and increase patient comfort. Nonetheless, postoperative shivering still occurred despite the adoption of heat preservation measures, such as increasing the operating room temperature, heating the flushing fluid, and keeping the quilts covered. Previous studies have demonstrated that thermal insulation of the active air preheater is effective (Desgranges et al., 2017).

The thermal sleeve for surgery in the lithotomy position is a type of inflatable heating tool that mainly uses air heating to ensure that the vented side continuously emits hot air, thus generating heat circulation around patients and preserving lower extremity heat. It is a low-cost easy-to-use physical heat preservation method with few side effects. The heating device is set to 40°C and can maintain patient temperature and reduce body heat emissions.

Furthermore, the results of the study showed that, despite no differences in patient entry temperature between the two groups, the body temperature in the control group continued to decline during the period from the skin incision to the end of the operation, whereas the body temperature increased in the test group; the difference was not statistically significant (p > 0.05). The number of patients suffering from postoperative shivering was much lower in the test group than in the control group.

Our study has several limitations. First, it is not a multicentered design and sample size is relatively small; additional multicentered studies are needed to further clarify the results of this study. Second, the anesthesia details such as anesthetic depth, the type, and dose of anesthetic drugs may affect the results, and these factors should be controlled in future study.

Conclusions

In summary, the use of a thermal sleeve for surgery in the lithotomy position during the operation process can help maintain patient body temperature, thus decreasing the occurrence of intraoperative hypothermia.

Footnotes

Acknowledgments

We are particularly grateful to all the people who have given us help for our article.

Authors' Contributions

C.-J.S. and B.-Y.Z. conceptualized and designed the study, drafted the initial article, and reviewed and revised the article. C.-J.S. and B.-Y.Z. designed the data collection instruments, collected data, carried out the initial analyses, and reviewed and revised the article. B.-Y.Z. coordinated and supervised data collection, and critically reviewed the article for important intellectual content. All authors approved the final article as submitted and agree to be accountable for all aspects of the study.

Ethics Approval and Consent to Participate

This study was conducted in accordance with the Declaration of Helsinki. This study was conducted with approval from the ethics committee of Tongde Hospital of Zhejiang Province. A written informed consent was obtained from all participants.

Consent for Publication

Consent for publication was obtained from every individual whose data are included in this article.

Availability of Data and Materials

The data sets used and/or analyzed during this study are available from the corresponding author on reasonable request.

Disclaimer

All authors have contributed significantly to the article and declare that the study is original and has not been submitted or published elsewhere.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

This study was supported by a grant from funding: Zhejiang Provincial Health Commission—New Technology Product R&D Project (No.: 2021PY041).

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