Effects of Optimal Temperature Control in Body Contouring Surgery: A Nonrandomized Controlled Clinical Trial

Abstract

Background

Perioperative hypothermia in plastic surgery has underestimated risks, including increased risk of infection, cardiac events, blood loss, prolonged recovery time, and increased nausea, pain, and opioid usage. Inadequate preventive measures can result in up to 4 hours of normothermia restoration.

Objectives

The aim was to compare the impact of different strategies for normothermia during plastic surgery procedures and their relationship with clinical outcomes.

Methods

A nonrandomized clinical trial was conducted in a single center in Bogota, Colombia. We enrolled adult patients undergoing body contouring surgery and divided them into 4 intervention groups with different measures to control body temperature. Univariate and bivariate analyses were performed, comparing several clinical symptoms to evaluate outcomes.

Results

A total of 197 patients were analyzed. Most of them were females (84.3%). Mean age was 38.6 years, and the median procedure duration was 260 minutes. Demographic and clinical characteristics did not exhibit significant differences between the groups. There were notable variations in temperature measurements at crucial moments during the surgical procedure among the groups, attributed to the implementation of distinct thermal protective strategies. Group comparisons showed a relationship between hypothermia and increased nausea, vomiting, shivering, pain, and additional analgesia requirements.

Conclusions

Incorporation of active thermal protective measures, such as Blanketrol or HotDog, during body contouring procedures, markedly diminishes the risk of hypothermia and enhances overall clinical outcomes. Implementing these active measures to maintain the patient in a state of normothermia not only improves operating room efficiency but also leads to a reduction in recovery room duration.

Level of Evidence: 3

Perioperative hypothermia has an increased risk for a wide range of significant and often underestimated adverse effects in plastic surgery procedures. Some of these effects include increased infection rates, increased blood loss, morbid cardiac events, prolonged recovery room and hospital stays, increased nausea, higher pain levels, and elevated opioid usage.^1-7 Both regional and general anesthesia alter the body's protective measures against hypothermia, and their combined use increases the risk.⁷ Without adequate preventive measures, restoring normothermia may take up to 4 hours.⁸ The onset of hypothermia is a primary determinant of intraoperative and postoperative complications, so it is imperative to avoid it.⁹

In 2018, Cohen et al described the association between long intraoperative periods with body temperatures below 35.6°C (96.1°F), and an increased incidence of hematomas or bleeding, in patients undergoing body contouring surgery.¹⁰ Coon et al also described that maintaining intraoperative temperatures at 35°C (95°F) or lower were associated with an increased risk of seroma formation, bleeding, and transfusion requirements.¹¹ Furthermore, hypothermia is related to multifactorial coagulopathy, involving defective release of thromboxane A2, alterations in platelet function, and coagulation cascade inhibition. These effects, despite their clinical significance, are often overlooked because most available coagulation tests are temperature-compensated.¹²

In a randomized clinical trial, Frank et al found that patients with routine thermal care were on average 1.3°C cooler than patients with more aggressive thermal control. Despite the small temperature difference, the incidence of perioperative cardiac events was 300% higher in the routine thermal care group.⁵ This correlation is attributed to the physiological respiratory and cardiovascular response to hypothermia, characterized by increased metabolic rate, oxygen consumption, and respiratory effort induced by shivering, noradrenaline-mediated peripheral vasoconstriction, and increased mean arterial pressure.¹³ Postoperative shivering is a common manifestation of hypothermia, contributing to increased patient discomfort and pain levels, subsequently increasing the requirement of opioids for analgesia management. This is furthermore associated with an increased risk of postoperative nausea and vomiting.⁷

Several protocols have been described for perioperative temperature control. The Rubin protocol, from the University of Pittsburgh, described air warmers and thermal blankets, keeping the surgical room temperature at 21°C (69.8°F), and warming the infiltration and intravenous solutions.⁹ In 2018, Bayter et al designed a list of recommendations for patients undergoing plastic surgeries longer than 1 hour. This guideline includes as pivotal measures warming the patient 1 hour before surgery employing thermal air blankets set at 39°C (102.2°F), warming the infiltration fluids to 37°C (98.6°F), and keeping the operating room between 20° and 22°C (68°-71.6°F).⁷ The implementation of these measures decreases the cold sensation, tremors, and pain, reduces the necessity for opioids, and is associated with less nausea and a shorter recovery room stay.⁷ To date, there are no studies describing evaluation of active measures for temperature control during the perioperative period, which could help consistently maintain normothermia, and be more beneficial for the patient and probably cost-effective.

METHODS

Study Design

A nonrandomized controlled clinical trial was conducted in a single plastic surgery center (Dhara Clinic, Bogotá, Colombia) from June 2022 to July 2023. This study was conducted following the Declaration of Helsinki and was approved by the institutional review board of our institution (Dhara Clinic, Bogota, Colombia). The study was considered a minimal risk. Nonprobabilistic convenience sampling was performed. Patients fulfilling selection criteria were invited to participate, and subsequently included, upon providing written informed consent before the study. The study was registered at Clinicaltrials.gov under protocol ID NormoT001 and approval number 001-01062022.

Patients

Our trial included adult patients, ages 18 to 60 years, undergoing body contouring procedures (liposuction or liposculpture), either individually or combined with a maximum of 2 other major aesthetic procedures involving the face, breast, or dermolipectomy. Only healthy patients without underlying comorbidities (classified as ASA ≤ II) were included. Exclusion criteria included females with a BMI >30 kg/m² and males with a BMI >32 kg/m², massive weight loss, and smoking. Eligible patients were approached and voluntarily consented to their participation in the study. All enrolled patients received the same anesthetic technique. Following the surgical procedures, patients were transferred to the postanesthesia recovery room, where according to the clinic's protocols they received thermal blankets and forced hot air at 38°C (100.4°F) with the temperature control system. For all patients, rigorous temperature curve monitoring was systematically conducted at 5 points in time: before anesthetic induction, after intubation, at the end of surgery, upon arrival to the recovery room, and before leaving the unit.

Intervention Groups

We compared 4 different intervention groups. Group 1 (control) involved patients with standard temperature management according to regular institutional protocol (preoperative and postoperative warming with hot air at 38°C), without any other preoperative or intraoperative thermal protection measures. Group 2 (passive thermal protection measures) had patients who underwent 1-hour preoperative warming with hot air at 38°C (100.4°F); an operating room (OR) temperature maintained at a minimum of 21°C (69.8°F); warming of aseptic and antiseptic solutions along with infiltration fluid to 38°C (100.4°F) through a medical grade device (Anova Precision; Anova Applied Electronics, Inc., San Francisco, CA); and maintenance of a dry surgical field as far as possible. In Group 3 (active thermal protection measures), patients received the same measures as Group 2, with the addition of continuous intraoperative temperature protection with a thermal convection blanket by water flow (Blanketrol; GENTHERM Medical, Cincinnati, OH) at 40°C (104°F). Group 4 (active thermal protection measures) included patients with the same measures as Group 2, adding permanent intraoperative thermal protection measures with conductive fabric electric warming devices (HotDog; Augustine Surgical, Inc., Eden Prairie, MN) at 40°C (104°F). For patients in groups 1, 2 and 3, the body contouring procedure was either liposculpture or high-definition liposculpture in combination with any other aesthetic procedure (mammaplasty, abdominoplasty, fat grafting, rhinoplasty, face liposuction, limb lipectomy, etc); meanwhile, all patients in Group 4 underwent high-definition liposculpture in addition to other procedures.

Data Collection

Variables for analysis included demographics, type of procedure, surgical time, prewarming time, use of prewarmed infiltration fluids, room temperature, patient’s body temperature (before anesthetic induction, after intubation, at the end of surgery, upon arrival to the recovery room, and before leaving the unit), time in recovery room, intensity of pain (measured by visual analog scale [VAS]) at awakening and before discharge from the unit, increased pain, requirement of analgesic reinforcement, and hypothermia symptoms (including nausea, vomiting, shivering, tremor). A body temperature above 37.8°C (100°F) was documented as fever. Data were collected and written down on a standard spreadsheet by a single nurse, blinded to the study methods and trained for data collection accuracy.

Statistical Analysis

Univariate analysis was performed to summarize the data. For qualitative variables, frequencies (absolute and relative) and percentages were estimated. For quantitative variables, normal distribution was evaluated with the Shapiro-Wilk test. For variables with normal distribution mean and standard deviation (SD) were calculated, whereas non-normal variables were reported as median and interquartile range (IQR). Subsequently, bivariate analysis was conducted to evaluate the association of the demographic, clinical, and surgical variables with the outcome (occurrence of hypothermia). Analysis of variance (ANOVA) tests were administered to compare the variances in quantitative variables across the groups. Thereafter, variables were recategorized as dichotomous categorical variables, to simplify the analysis, and Fisher's exact test was performed. Statistical analysis was carried out with Jamovi computer software (Version 2.3).

RESULTS

Trial Population and Intervention Groups

A total of 197 patients undergoing aesthetic surgical procedures were included in our clinical trial. Most patients were female (n = 166, 84.3%), with a mean age of 38.6 years (SD 8.3 years) and a range of 18-60 years, median weight of 66 kg (IQR 15 kg), median height 1.65 m (IQR 0.11 m), and median body mass index (BMI) of 24.8 kg/m2 (SD 2.74 kg/m2). All patients received general anesthesia, the majority underwent 2 or 3 simultaneous surgical procedures (75.6%), and the median duration of surgery was 260 minutes (IQR 80 minutes), with 89.8% of the procedures considered prolonged surgeries (exceeding the 3-hour threshold). Demographic, clinical, and surgical information is described in Table 1. Increased pain during recovery was reported by 39.1% of patients, and 66% of them required additional analgesic management. Patient distribution was as follows: Group 1 (control) 43; Group 2 (passive thermal protection) 51; Group 3 (active thermal protection with Blanketrol) 55; and Group 4 (active thermal protection with HotDog) 48. Although male inclusion in the trial was relatively low, Group 3 exhibited a higher frequency of males compared to the other groups. In contrast, the distribution of female patients was homogeneous across groups. The groups did not exhibit statistically significant differences in demographic parameters, including age, weight, height, and BMI (Supplemental Table 1, located online at www.aestheticsurgeryjournal.com). Upon comparing variables related to the surgical procedure, pain at discharge showed a statistically significant difference (P = .022), however, this variation was only 1 point on the VAS, therefore considered not clinically significant. VAS is a subjective pain assessment by patients; consequently, it is not feasible to attribute clinical significance between a 2 or 3 score on the scale. Supplemental Table 1 summarizes additional clinical characteristics and their comparisons.

Overall Temperature Behavior

Temperature measurements at the 5 designated moments were compared across all groups. A statistically significant difference was noted before the induction of anesthesia, after intubation, and at discharge, although the clinical significance of these variances was irrelevant. Conversely, at the end of surgery and upon arrival in the recovery room, temperatures showed both statistical and clinical significance, with higher readings observed in groups 3 and 4. Table 2 and Figure 1 provide a comprehensive summary of the comparisons and temperature measurements among all groups.

Thermal Protection Measures and Other Outcomes

The association of the effects of temperature protection measures and clinical outcomes was explored, combining groups 2, 3, and 4 as thermal protection groups, compared to taking no action (control; Group 1). The analysis demonstrated that patients without temperature protection measures had a 224% higher likelihood of hypothermia at the end of surgery (prevalence ratio [PR] = 3.24, P < .001, CI 95% 2.4-4.2). All other explored variables showed no statistically significant difference (Table 3). A comparison of the occurrence of postoperative outcomes was performed between the individual groups; see Supplemental Tables 2, 3, and 4, located online at www.aestheticsurgeryjournal.com, for details. Upon comparing Group 1 with the other groups, data showed a significantly elevated likelihood of hypothermia within Group 1 (by 1220% compared to Group 3, and 1310% to Group 4). Furthermore, Group 3 showed a decreased probability of shivering and tremors, whereas Group 4 demonstrated a reduced likelihood of nausea and vomiting. Upon comparing Group 2 with the other groups, a significantly elevated probability of hypothermia in Group 2 was found (by 840% compared to Group 3, and 1000% to Group 4). Additionally, data showed a 42% lower probability of requiring additional analgesia to control pain in both Groups 3 and 4. In the final analysis comparing Group 3 with Group 4, a 28% increased likelihood of experiencing intense pain upon awakening (VAS pain >4) was evidenced in the patients in Group 4. Unexpectedly, male patients had a 36% higher likelihood of having mild pain upon awakening than females (PR = 0.73, P = .01, CI 95% 0.5-0.99), and overweight patients had a 132% higher probability of experiencing shivering compared to normal BMI patients (PR = 0.43, P = .007, CI 95% 0.3-0.8). See Supplemental Tables 5 and 6, located online at www.aestheticsurgeryjournal.com, for details.

DISCUSSION

Normal temperature regulation in the human body is a complex and finely tuned process. Thermoregulation is crucial for maintaining stable and optimal functioning of various biochemical and physiological processes. Average normal body temperature is around 98.6°F (37°C), although there can be slight variations among individuals. The hypothalamus serves as the central thermostat by receiving input from peripheral receptors and coordinating responses to maintain a constant temperature within a narrow range of 97.8°F to 99.1°F (36.5°C to 37.3°C). Some of these responses include vasodilation and vasoconstriction of the superficial blood vessels; sweating, which helps to cool the body through evaporation; involuntary muscle contractions (shivering) in response to low temperature; metabolic rate adjustment to increase or decrease energy expenditure (generate heat); and other behavioral responses.

Patients in the OR lose some of these regulatory mechanisms due to medications, unconsciousness, and the physiologic effects of hypothermia, which can have serious consequences if not addressed promptly. Temperature control plays a pivotal role in high-definition liposculpture (HDL), influencing both the safety and overall aesthetic outcomes. Maintaining optimal temperatures contributes to minimized trauma, reduced bleeding, and improved skin retraction.^7,14 Our study focused on different strategies to maintain the patient in normothermia throughout the entire surgical procedure and compared the clinical outcomes after implementing them. In recent years, a robust quota of medical research in aesthetic plastic surgery has shown interest in safety practices, rather than just describing new techniques or procedures.

In this study, we demonstrated the positive impact on clinical outcomes resulting from the implementation of active thermal protection measures during the perioperative period in patients undergoing liposculpture, either with Blanketrol or HotDog. Moreover, all the patients included in Group 4 (HotDog) underwent HDL, which is a more invasive and aggressive procedure than liposuction. However, the temperature protection measures in this group managed to maintain the thermal control of the patients, resulting in better clinical outcomes than groups 1 and 2, which included HDL and liposuction patients. Our findings set a new standard of keeping the patient at normal body temperature throughout the procedure to avoid the deleterious effects of hypothermia, such as shivering, tremors, nausea, vomiting, pain, and the increased requirement for analgesia. In the randomized controlled trial conducted by Bayter-Marin et al, they found that 122 patients undergoing body contouring procedures with active thermal protection measures had a 58% shorter recovery room duration, compared to patients receiving passive thermal protection or no measures.⁷ Consistent with our findings, Bayter-Marin et al also found better clinical outcomes in the active thermal protection group, with respect to cold feeling, shivering, pain levels, and opioid usage.⁷ However, they did not incorporate additional technologies such as the thermal convection blanket by water flow (Blanketrol) or the conductive fabric electric warming device (HotDog). Our results demonstrate that both of these technologies had a significant impact on clinical outcomes for patients undergoing body contouring procedures. Notably, the reduced need for postoperative analgesia represents a substantial advancement in minimizing opioids during the postoperative period, particularly for elective procedures with cosmetic intent. In our experience, postoperative shivering, chills, nausea, and vomiting have proven to be emotionally distressing experiences for patients following cosmetic procedures. Given our remarkable success in nearly eliminating such events through the integration of these technologies into our practice, we were prompted to conduct a comprehensive clinical trial to look for their true effects. Consequently, we enlisted different surgeons from our institution, all trained in HDL techniques and working under identical clinical conditions. Previous research has shown the benefits of thermal protective measures in providing a safer environment for the patient when HDL is performed. In fact, Hoyos et al showed that after almost 20 years of preforming HDL, the incorporation of thermal protective measures, among other strategies, allowed them to actually increase the amount of lipoaspirate without any clinical consequences to the patient, and in fact improving the overall postoperative outcomes.¹⁴

Surprisingly, beyond its influence on patient outcomes, our study indirectly contributes to optimizing operating room efficiency and cost savings by reducing delays in patient discharge from the recovery room. Further comparisons between these 2 technologies and the cost-effectiveness implications are subjective and necessitate more extensive data to provide reliable economic statements. Nonetheless, the findings of this study carry the potential for significant impact on the global scientific community in the management of patient safety during body contouring surgery. Although this clinical trial exhibits a low potential for bias, it also presents a challenge to generalization. It was not randomized, involved mostly Colombian patients, and had limited representation of males. Although a longer follow-up period with postoperative laboratory analysis and additional metrics would have been preferable, the limitations imposed by the surgeons' reluctance to incur additional procedural costs and the patients' lack of commitment to adhere to specific protocols constrained our study's time frame. However, the extensive evidence from cardiothoracic surgery (as well as other surgical specialties) regarding the benefits of normothermia and the deleterious effects from mild hypothermia in patients undergoing cardiac procedures led us to question the necessity of an extended follow-up period.^15-17 As typical for body contouring procedures, patients were followed for at least 2 weeks physically and 6 months by virtual appointments, but this was not included in the protocol of our study, so no information can be disclosed.

CONCLUSIONS

Striking the right balance in temperature management is crucial for achieving optimal results in body contouring, ensuring a safe and effective procedure with enhanced aesthetic outcomes. Active thermal protective measures should be the new standard of care for high-definition body contouring procedures. Both Blanketrol and HotDog are helpful devices for protecting the patient from hypothermia and its deleterious effects in the early postoperative period. Further research comparing the cost-benefit ratio of these 2 technologies may provide further information for clinicians.

Supplemental Material

This article contains supplemental material located online at www.aestheticsurgeryjournal.com.

Disclosures

Dr Hoyos performs as a speaker for InMode (Irvine, CA), and receives loyalties, compensation, sponsorships from InMode. No sponsorship or economic support has been provided for this study by InMode. The remaining authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.

Funding

The authors received no financial support for the research, authorship, and publication of this article.

REFERENCES

Author notes