Effects of different insulation temperatures of an inflatable insulation system on patients receiving right hemicolectomy using the laparoscopic caudal approach

General anesthetics administered to patients undergoing surgery for colorectal cancer may cause hypothalamic thermoregulatory center damage, thus reducing the body's heat production. Moreover, the loss of body heat may increase due to intraoperative body exposure and fluid infusion, thus causing hypothermia and increasing the risk of adverse reactions such as shivering and arrhythmia, which may adversely affect the prognosis [1, 2]. Consequently, for individuals undergoing colorectal cancer surgery, effective heat preservation measures should be taken to reduce the occurrence of adverse events, thus ensuring smooth operation [3]. As a medical heat preservation device, forced-air warming blankets are capable of elevating the body surface temperature of patients through warming air at a constant temperature and exerting favorable heat preservation effects. Several temperature tranches of control were set in the main engine of a forced-air warming system, such as natural wind, 38°C and 43°C, and reinforcement (45°C) in some [4, 5]. At present, the issues regarding selection of temperature tranches of control, heat preservation and selection timing of different temperatures, and adjusting methods of producing temperatures in forced-air warming systems remain elusive. Although the superior effects of a forced-air warming system on improving intraoperative hypothermia are well-documented, no consensus has been reached on the selection of a heat preservation regimen in such a system during surgery for colorectal cancer. Therefore, this study aimed to investigate the application effects of different temperature tranches of control in a forced-air warming system on the well-being of patients undergoing right hemicolectomy using the laparoscopic caudal approach.

This prospective randomized study was conducted on patients with colorectal cancer admitted to our hospital from January 2019 to June 2021. The inclusion criteria were as follows: a) patients receiving right hemicolectomy using the laparoscopic caudal approach, b) those aged ≥18 years old, who agreed to participate in this study and who signed the informed consent along with their families, c) those in American Society of Anesthesiologists (ASA) grades I, II, and III, d) those with normal basal body temperature, namely average temperature of 36–37°C within 3 days preoperatively in the ward, e) those without complications such as intestinal obstruction and perforation requiring emergency surgery, and f) those without medication affecting body temperature within 2 weeks prior to operation. The exclusion criteria involved: a) patients who could not tolerate the relevant drugs in this study, b) those with organic lesions in vital organs, c) those with coagulation dysfunction or blood system diseases in the past, d) those with a history of thrombosis or cerebral infarction, e) those with certain diseases that could change body temperature, or f) those with a body mass index (BMI) exceeding the normal body mass (18.5–24.9 kg/m²) by ±20%. After 7 patients were excluded, 132 were finally enrolled and divided into four groups using a random number table. The forced-air warming system was utilized immediately when patients entered the operating room. Flushing fluid heated to 37°C was used intraoperatively, and infusion fluid was heated to 37°C by an infusion heater. Different temperatures were adopted in four groups for heat preservation: Group A (high-grade heat preservation group, 43 °C), Group B (low-grade heat preservation group, 38°C), Group C (comprehensive heat preservation group, 43 °C for 1 h and then automatically adjusted to 38 °C), and Group D (routine heat preservation group) (dynamically adjusted by operating room nurse according to patient's real-time core temperature). When the patient woke up and was sent out of the operating room, the warming system was removed. No significant differences were found in general data among the four groups of patients (P > 0.05) (Table 1).

Intravenous-inhalation combined anesthesia was performed. Patients were administered oxygen inhalation using masks, and intravenous drip of midazolam (0.05–0.1 mg/kg), fentanyl (3 μg/kg), and cisatracurium (0.1–0.3 mg/kg) to induce general anesthesia. Next, a temperature probe was placed in the patient's nasopharynx to monitor the nasopharynx temperature. Then the patients were given endotracheal intubation and mechanical ventilation using a volume-controlled mode, with controlled oxygen flow at 2 L/min, oxygen concentration of 60%, end-tidal carbon dioxide partial pressure (P_ETCO₂) of 35–45 mmHg (1 mmHg = 0.133 kPa), and tidal volume of 8–10 mL/kg. With respect to anesthesia maintenance, patients received continuous intravenous drip of propofol 5–6 mg/(kg·h) and remifentanil 0.1–0.15 μg/(kg·h), intermittent injection of atracurium, and continuous inhalation of sevoflurane (2–3%). The operating room temperature and humidity were maintained at 24–26°C and 40–60%, respectively. After entering the operating room, the patients were placed in a supine position on the warming blanket. Different temperatures were adopted in four groups for heat preservation, including Group A (high-grade heat preservation group, 43°C), Group B (low-grade heat preservation group, 38°C), Group C (comprehensive heat preservation group, 43°C for 1 h and then automatically adjusted to 38°C), and Group D (routine heat preservation group) (dynamically adjusted by operating room nurse according to patient's real-time core temperature). The forced-air warming blanket covered patient's four limbs and then fixed, and when the patient woke up and was sent out of the operating room, the warming system was removed. During operation, patient's vital signs such as blood pressure and heart rate were closely monitored, the changes of electrocardiogram were observed dynamically, and the venous infusion pathway was established.

Pulmonary artery, lower esophagus, nasopharynx, and tympanic membrane were often selected to monitor core temperature during operation, while nasopharynx and tympanic temperatures were readily accessible and thus more commonly used [6]. During operation, Medlinket Temperature Sensor (model: W0001F) produced by Shenzhen Med-Link Electronics Tech Co., Ltd. was connected with Monitor B450-01 (GE Healthcare) to measure the nasopharynx temperature of patients at 5 min before induction of general anesthesia (T0), immediately after induction of general anesthesia (T1), 30 min after induction of general anesthesia (T2), 60 min after induction of general anesthesia (T3), 120 min after induction of general anesthesia (T4), and at the end of operation (T5).

Peripheral venous blood was extracted from each patient at three different time points, namely before operation (T0), during operation (T3), and after operation (T5). The blood coagulation indices of patients, including prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and fibrinogen (FIB) were determined by a CA-7000 full-automatic coagulation analyzer (Sysmex Corporation, Japan).

Detection of hemodynamic parameters: The mean arterial pressure (MAP), heart rate (HR), and central venous pressure (CVP) were measured using Monitor B450-01 (GE Healthcare) at 5 min before induction of general anesthesia (T0), immediately after induction of general anesthesia (T1), 30 min after induction of general anesthesia (T2), 60 min after induction of general anesthesia (T3), 120 min after induction of general anesthesia (T4), and at the end of operation (T5).

Detection of neuroendocrine indicators: The rapid blood glucose was tested by GM505EA CareSens POP Blood Glucose Monitoring System at three different time points, namely before operation (T0), during operation (T3), and after operation (T5).

Detection of cytokines: About 3 mL of peripheral blood was extracted and centrifuged. Then the serum was obtained and stored in a refrigerator at 80 °C. Enzyme-linked immunosorbent assay (ELISA) was employed to detect the serum levels of C-reactive protein (CRP), interleukin (IL)-1β, IL-6, IL-17A, and tumor necrosis factor (TNF)-α before operation (T0) and after operation (T5). The kits were purchased from Hangzhou Lianke Biotechnology Co., Ltd.

Recording of anesthesia waking time: The patient was deemed to be wakened if he had an eye-opening movement when someone called his name, and the period from cessation of sevoflurane inhalation to eye-opening movement when called was regarded as anesthesia waking time [7].

Recording of extubation time: The period from cessation of sevoflurane inhalation to extubation of endotracheal tube was considered as extubation time. With satisfactory tidal volume during spontaneous breathing, P_ETCO₂ < 50 mmHg was the criterion for extubation of the endotracheal tube [8].

Bispectral index (BIS) was used to monitor the functional state and changes of cerebral cortex, with certain sensitivity in predicting somatic movement, intraoperative awareness, and the loss and recovery of consciousness.⁷ In terms of BIS, zero represented the absence of electroencephalographic seizure activity, namely cerebral cortex inhibition, and 100 meant a waking state. The BIS value was 85–100 normally, 65–85 for a sedated state, 45–65 for an anesthetic state, and below 40 for a burst suppression state [9, 10]. Moreover, relevant studies have shown that following rapid metabolism in the body, the changes in plasma concentration or effect compartment concentration of propofol were remarkably associated with sedation changes monitored by BIS [11, 12]. Therefore, this study was carried out to measure BIS value at propofol discontinuation, time from propofol discontinuation to BIS ≥ 80, and propofol effect compartment concentration at BIS ≥ 80. In the present study, Disposable sensor 186–0106 (Covidien, USA) was connected with BIS EEG VISTA (Covidien, USA) to monitor the BIS of patients during operation.

BIS value at propofol discontinuation: BIS value when propofol was discontinued.

Time from propofol discontinuation to BIS ≥ 80: The time from discontinuation of propofol to BIS ≥ 80 was recorded.

Propofol effect compartment concentration at BIS ≥ 80: The propofol effect compartment concentration displayed by the TCI pump at BIS ≥ 80 was recorded.

SPSS 20.0 software was used for statistical analysis. Measurement data were expressed as mean ± standard deviation (χ ± s). One-way variance of analysis was employed for comparisons among multiple groups. The LSD method was used for pairwise comparisons. The t-test was utilized for intragroup comparisons before and after operation. Numerical data were analyzed using the chi-square or Fisher's exact test. P < 0.05 was considered statistically significant.

No significant differences were found in operation time, anesthesia duration, intraoperative blood loss, intraoperative infusion volume, urine volume, and abdominal flushing volume among the four groups of patients (P > 0.05) (Table 2).

The difference in nasopharyngeal temperature was not significant among the four groups of patients at T0, T1, and T2 (P > 0.05). At T3, T4, and T5, the nasopharyngeal temperature was significantly higher in Group A and Group C than that in Group B and Group D, while it was the highest in Group A (P < 0.05) (Figure 1).

Fig. 1

APTT, TT, and FIB showed no significant differences among the four groups at T0, T3, and T5 (P > 0.05). PT was higher in the four groups at T3 than that at T0 and T5, suggesting a certain stress state of patients during operation. At T3, PT was significantly lower in Group A and Group C than that in Group B and Group D, and it was the lowest in Group C, followed by Group A (P < 0.05) (Figure 2).

Fig. 2

At T0, IL-1, IL-6, IL-12, IL-23, IL-13, IL-17A, TNF-α, and CRP levels exhibited no significant differences among the four groups (P > 0.05), while they were significantly increased in the four groups at T3 and T5. Group C had significantly lower levels of IL-1, IL-6, IL-23, IL-13, IL-17A, TNF-α, and CRP but a significantly higher level of IL-12 than the other three groups (P < 0.05) (Figure 3).

Fig. 3

The difference in MAP, HR, and CVP showed no statistical significance among the four groups at T0 and T1 (P > 0.05). MAP and HR were significantly lower in Group A and Group C than those in Group B and Group D at T2, T3, and T4, and they were the lowest in Group C (P < 0.05) (Figure 4).

Fig. 4

At T0, there was no significant difference in rapid blood glucose among the four groups (P > 0.05). As the operation progressed, an upward trend was found in the blood glucose level of patients in the four groups, and it did not return to normal until the end of operation. The blood glucose level was lower in Group A and Group C than that in Group B and Group D at T3 and T5, and it was the lowest in Group C (P < 0.05) (Figure 5).

Fig. 5

The anesthesia waking time and extubation time were shorter in Group A and Group C than those in Group B and Group D, and they were the shortest in Group C (P < 0.05) (Table 3).

No significant difference was found in BIS value at propofol discontinuation in each group (P > 0.05). Group C had a significantly shorter time from propofol discontinuation to BIS ≥ 80 than the other three groups, and propofol effect compartment concentration at BIS ≥ 80 was significantly higher in Group C than that in the other three groups (P < 0.05) (Table 4).

The intervention frequency was the highest in Group D, comparable between Group A and Group B, and the lowest in Group C (P < 0.05) (Table 5).

Colorectal cancer ranks sixth and fifth in terms of morbidity and mortality in China [13]. Patients with colorectal cancer are usually treated by surgery. During operation, surgical incision, intestinal canal, peritoneum, and peritoneal contents are largely exposed to the cold environment of the operating room. More water evaporation due to complex operation and longer operation time may lead to heat dissipation exceeding heat production in the body. In particular, the liver, as the organ with the largest heat production, may consume more heat while exposed to the low temperature for a long time. In addition, a large amount of flushing fluid is needed during the operation. All factors mentioned above can reduce the body temperature notably, leading to hypothermia [14, 15]. Individuals with intraoperative body temperature < 36°C are diagnosed with intraoperative hypothermia [16], which may cause shivering, cardiac dysfunction, coagulation disorders, metabolic abnormalities, immune dysfunction, elevated oxygen consumption, increased bleeding and delayed postoperative awakening, and even death [17, 18]. Therefore, hypothermia should be prevented during colorectal cancer surgery, thus avoiding the adverse effects.

For patients undergoing colorectal cancer surgery, active heating by means of a forced-air warming system can effectively prevent perioperative hypothermia [19, 20]. In light of guidelines for intraoperative temperature management issued by the American Society of PeriAnesthesia Nurses (ASPAN) [21] and the UK National Institute for Health and Care Excellence (NICE) [22], forced-air warming system is recommended as the standard measure for active heating during operation. Moreover, a forced-air warming system also serves as a safe, effective and widely used method for heat preservation, as proposed in Perioperative Standards and Recommended Practices by the Association of Operating Room Nurses (AORN) in 2014 [20]. In addition, according to the expert consensus on the prevention and treatment of perioperative hypothermia issued in China in 2017 [6], a forced-air warming system, which is extensively applied for active heating, is safe and effective. Therefore, it is recommended to adopt a forced-air warming system for active heat preservation during operation, especially for patients undergoing surgery lasting for ≥ 30 min. Although numerous studies have confirmed the predominant effects of forced-air warming system on improving intraoperative hypothermia, the choice of heat preservation regimen in such system during surgery for colorectal cancer remains controversial. Thus, this study was conducted to compare the effects of different temperatures in the use of a forced-air warming system for heat preservation on the nursing of patients undergoing right hemicolectomy. The comprehensive heat preservation group (43°C for 1 h and then automatically adjusted to 38°C) was prominently superior to other groups, as evidenced by perioperative core temperature, blood coagulation indices, and stress indicators.

In conclusion, comprehensive heat preservation (43°C for 1 h and then automatically adjusted to 38°C) has favorable effects on right hemicolectomy, which is worthy of clinical promotion and application.