The Effect of Warmed Hysteroscopic Fluid-Distention Medium on Postoperative Core Body Temperature: A Randomized Trial

Abstract

Objective:

Operative hysteroscopy is considered a minimally invasive and effective treatment approach for submucosal uterine leiomyoma, endometrial polyps, Müllerian anomalies, and other conditions that result in abnormal uterine bleeding and/or infertility. Given the systemic absorption inherent in resectoscopic surgery, the primary aim of this study was to determine if warming distention-fluid medium during operative hysteroscopy performed under intravenous (IV) sedation with monitored anesthesia care would affect patients' perioperative core body temperatures, and secondarily, to assess patients' postoperative self-rated pain scores.

Materials and Methods:

For this single-blinded, 3-armed, stratified randomized trial (Level 2b Oxford Centre for Evidence-based Medicine Levels of Evidence 2009), 96 patients from a minimally invasive gynecologic surgery clinic in an academic-affiliated community hospital were enrolled. A computer-generated randomization sequence was used to allocate patients randomly to 3 groups. Group 1 had normal saline-distention medium-fluid bags at room temperature, defined as 22°C (71.6°F). Group 2 had fluid bags pulled from a warming-cabinet set at 40°C (104°F) as standardized by the Joint Commission on National Quality Approval. Group 3 had continuously warmed fluid by an automated fluid-management system with a function that warms the distention medium to 40°C (104°F) continually. Randomization was stratified by procedure type (myomectomy and nonmyomectomy), so that 50% of the cases for each fluid-temperature category included resections of submucosal leiomyomas. Pre- and postoperative near-core body temperatures and pain scores; operative times; and hysteroscopic fluid temperatures, pressures, and fluid deficits were recorded. Intention-to-treat analysis was performed.

Results:

There was no statistically significant differences among the 3 arms of the trial for the primary outcome of near-core body temperature or for the secondary outcome of self-rated pain scores. However, when comparing patients undergoing hysteroscopic myomectomy with patients undergoing nonmyomectomy hysteroscopic procedures, there were higher fluid deficits and operative times in the hysteroscopic myomectomy patients in groups 1 and 2 (room-temperature fluid and passively warmed fluid, respectively), but not in group 3 (continuously warmed fluid). Group 3 had no statistically significant differences in average fluid deficit, when comparing hysteroscopic myomectomy to all other procedure types. This finding held true although there was no statistically significant differences in total procedure times between the myomectomy procedures and all other surgical procedure types within group 3.

Conclusions:

Warming hysteroscopic distention media did not affect near-core body temperature or postoperative pain scores. Use of continuously warmed hysteroscopic fluid in hysteroscopic myomectomy might decrease operative times as well as volume of hysteroscopic fluid deficits. Use of an automated fluid-management system that has the capacity to warm fluid-distention medium continuously can be advantageous to gynecologic surgeons, as this intervention is simple, low-cost, and safe. Further studies to assess the relationship between the temperature of distention medium and surgical outcomes are recommended, specifically surrounding the relationship between operative times and fluid absorption.

Introduction

Operative hysteroscopy is frequently performed in an ambulatory surgical setting to address a wide variety of gynecologic pathologies via a minimally invasive approach. The National Institute for Health Care Excellence (NICE) has set a standard of maintaining a core body temperature above 36°C in the perioperative period,¹ as drops in core temperature of as little as 1°C below this level have been associated with adverse outcomes including increased risk of surgical-site infection^2,3 and increased surgical blood loss.⁴ NICE guidelines recommend that, when 500 mL or more intravenous (IV) fluids are infused, they should be warmed to 37°C using a fluid-warming device.¹ A Cochrane Review in 2015 evaluated the available literature regarding prevention of perioperative hypothermia and concluded that warmed IV fluids resulted in patients being ∼0.5°C warmer than those with room-temperature IV fluids, and noted further that even a small increase can be significant when patients are at risk of dropping into the mild hypothermic range, as they can then reach normothermia.⁵

Within gynecology, hysteroscopic procedures, such as myomectomy, are recognized for being a risk of fluid absorption. This occurs because the bipolar or monopolar diathermy used for surgical resection of type 1 and type 2 leiomyomas breeches the integrity of the myometrium, resulting in fluid intravasation into the venous bed secondary to the higher hydrostatic pressures, compared to venous intravascular pressures. Current American Association of Gynecologic Laparoscopists (AAGL) guidelines for operative hysteroscopy using isotonic-distention media, such as normal saline, recommend limiting the fluid deficit to 2500 mL to restrict intravasation of significant volumes of fluid and thereby prevent the onset of dangerous sequelae associated with fluid overload, such as right-sided heart failure and pulmonary edema.⁶ Given the systemic absorption inherent to hysteroscopic myomectomy, warmed hysteroscopic fluid-distention media arguably could assist in maintaining core body temperature at an optimal range in the perioperative setting; however, this has yet to be evaluated in the current gynecologic literature.

The AAGL guidelines make no comment about the temperature of the fluid-distention media recommended for hysteroscopy,⁶ and thus reflects the subjective and varied practices across the nation among gynecologic surgeons. Automated hysteroscopic fluid-management systems that monitor fluid deficit precisely and warm the fluid-distention medium are currently marketed with the theory/hypothesis that warm fluid can decrease patient discomfort. There is 1 randomized controlled study that evaluated this concept. Evangelista et al.⁷ compared pain intensity and degree of patient satisfaction during diagnostic office hysteroscopy and found no statistically significant difference between patients who received room-temperature fluid-distention media compared to warmed fluid. As this study involved only diagnostic procedures with an average procedure time of ∼3 minutes, it is possible that the study design led to systematic error biasing results to the null. Thus, the clinical question might yet remain at large.

The primary purpose of the current study was to determine if warming distention-fluid media during operative hysteroscopy performed under IV sedation with monitored anesthesia care would have an effect on patients' perioperative core body temperature. The secondary aim was to assess patients' postoperative self-rated pain scores. To the current authors' knowledge, there are currently no published studies evaluating the effect of either room-temperature or warmed hysteroscopic distention media on core body temperature, nor are there any published studies evaluating the effect of warmed distention media on postoperative pain scores after operative hysteroscopic procedures performed under IV sedation with monitored anesthesia care.

Materials and Methods

This study was a 3-armed, stratified, single-blinded randomized trial of patients undergoing operative hysteroscopy in the operating room (OR) under IV sedation with monitored anesthesia care at a single institution (Newton-Wellesley Hospital, Newton, MA). A computer-generated randomization sequence was used to allocate patients randomly to 3 groups: group 1 received normal-saline, distention-medium fluid bags at room temperature, defined as 22°C (71.6°F); group 2 to received fluid bags pulled from a warming cabinet set at 40°C (104°F) as standardized by the Joint Commission on National Quality Approval; and group 3 received continuously warmed fluid using an automated fluid-management system with a function that warms the distention medium continually to 40°C (104°F). The patients, as well as the nurses in the postoperative recovery unit (PACU), were blinded to the patients' randomized assigned arms of the trial. A stratified randomization by procedure type (myomectomy procedure versus all other procedure types) was used to ensure that this variable was evenly distributed across all groups than chance alone might ensure, as intravasation of fluid associated with myomectomy is the greatest potential confounding factor identified. The study was approved by the institutional review board (IRB) of Newton Wellesley Hospital.

Patients were enrolled between February 2016 and December 2017. Any patient seen in the minimally invasive gynecologic surgery department at the hospital—an academic-affiliated community hospital—who was scheduled for operative hysteroscopy under IV sedation in the OR was approached to participate in the study. Patients were recruited during the routine informed consent process in the preoperative unit on the days of their procedures. Patients were given verbal and written information pertaining to the study. Non–English-speaking patients were included in the study and were provided with Spanish-language consent forms.

Operative hysteroscopic surgeries included the following procedures: lysis of adhesions; polypectomy; metroplasty; resection of products of conception; endomyometrial resection; isthmocele repair; tubal recanalization; and myomectomy. All procedures were performed by 1 of 3 faculty, minimally invasive gynecologic surgeons with either a fellow or resident assist. A surgical standardization protocol was instituted for the study and included the following structure for all study cases: ambient OR temperature maintained at 20.5°C (70°F ± 1°F); no forced-air patient warming device used during the procedure; 3 warmed blankets placed across the torso; restriction of IV fluids to run at keep-vein-open flow and administered at room temperature or ∼22°C (71.6°F); use of normal saline hysteroscopic fluid-distention media, and use of a bipolar resectoscope or Karl Storz hysteroscopic instruments for all cases. The Thermedx^® FluidSmart™ Fluid Management System (Allen Medical automated fluid-management system) was used for all cases, and the warming function that warms the distention medium to 40°C (104°F) continually was only turned on for the third arm of the trial, which involved the group who was randomized to receive continuously warmed fluid.

The patients' body temperatures were recorded by a study investigator using the Temp-Plus II digital thermometer sublingual thermometer device (Model 2080, Alaris Medical Systems, Baesweiler, Germany)—with an accuracy of ±0.1°C—at 4 timepoints during the study:⁸ T1 in the preoperative unit; T2 at procedure starting time in the OR; T3 at procedure end time in the OR; and T4 upon arrival in the PACU. Postoperative pain scores were measured using a visual analogue scale (VAS), which has been validated with good evidence and good reliability, and that, overall, is highly correlated with other pain-measure scores.⁹ The VAS scores were self-reported and were recorded by the PACU nurse during the postoperative recovery phase.

The fluid-management system provided a digital printout at the conclusion of each case, detailing the variables collected in the study, including average temperature of the fluid instilled, total volume of fluid instilled, calculated hysteroscopic fluid deficit, procedure start time, and procedure end time.

Sample size calculation for the trial was based on the Cochrane Review⁵ that examined the available literature with 11 studies of moderate quality of evidence, including 682 patients, in whom the mean temperature was reported to be 0.63°C higher (95% confidence interval: 0.28–0.98°C) at the end of procedures that used warmed irrigation fluids, compared to procedures that did not. Thus, to detect a difference of 1°C in mean core body temperature among the groups in this study, a sample size of 30 subjects per study arm was calculated, using an α of 0.05 and a ß of 0.2 to provide 80% power. To account for fallout in data collection, the target enrollment was 32 patients per arm for a total of 96 patients.

Statistical analysis was performed using Stata 14.0 software. Continuous variables were assessed by one-way analysis of variance among the groups. The number of patients, and their mean values and percentages were analyzed. A p-value <0.05 was considered to be statistically significant. Intention-to-treat allocation was performed.

Results

A total of 96 patients were enrolled into the study. Six patients were excluded after enrollment due to incomplete temperature data; 3 patients from group 2, patients from group 3, and 1 patient from group 1. There was no loss to follow-up, given that the study was completed at the conclusion of the surgical procedure. Baseline patient characteristics and surgical data are detailed in Table 1. The majority of patients were premenopausal, with a mean age of 42.7, and self-identified as Caucasian (75.6%). Owing to the stratified design during randomization, half of the surgical procedures within each fluid-temperature group were comprised of hysteroscopic myomectomies. No preoperative treatment (e.g., gonadotropin-releasing hormone–agonists or ulipristal acetate) or intraoperative medications (e.g., vasopressin, misoprostol, methergine, carboprost, tranexamic acid, or oxytocin) were used in any of the surgeries performed. There were no intraoperative complications, such as uterine perforation, noted at the time of surgery, as confirmed by a review of the operative reports. A second procedure was required to complete resection of large submucosal myomas in 2 cases (2.2%).

Table 1.

Patient Baseline Characteristics & Surgical Data

Patients' information	Room-temperature fluid (group 1, n = 29)	Warming-cabinet fluid (group 2, n = 31)	Continuously warmed fluid (group 3, n = 30)	All patients (n = 90)
Age (in years)	44 ± 12.4	42.6 ± 12.0	41.7 ± 10.2	42.7 ± 11.5
Premenopausal
Yes	22 (75.9%)	26 (83.9%)	26 (86.7%)	74 (82.2%)
Race
Caucasian	24 (82.8%)	21 (67.7%)	23 (76.7%)	68 (75.6%)
Black	2 (6.9%)	7 (22.6%)	4 (13.3%)	13 (14.4%)
Asian	3 (10.3%)	3 (9.7%)	1 (3.3%)	7 (7.8%)
Other/declined to answer	0	0	2 (6.7%)	2 (2.2%)
Hysteroscopy procedure
Myomectomy	13 (44.8%)	14 (45.2%)	15 (50.0%)	42 (46.7%)
All other types	16 (55.2%)	17 (54.8%)	15 (50.0%)	48 (53.3%)
Polypectomy	10 (62.5%)	9 (52.9%)	8 (53.3%)
Lysis adhesions	4 (25.0%)	6 (35.3%)	1 (6.7%)
Retained POC	1 (6.3%)	2 (11.8%)	1 (6.7%)
Metroplasty	0	0	1 (6.7%)
Isthmocele repair	0	0	1 (6.7%)
Tubal recanulization	0	0	1 (6.7%)
Endometrial sampling	1 (6.3%)	0	1 (6.7%)
Endomyometrial resection	0	0	1 (6.7%)
2nd procedure needed to complete operation	1 (3.4%)	1 (3.2%)	0	2 (2.2%)
Intraoperative complications	0	0	0	0
Total procedure times (in minutes)	29.1 ± 18.3	37.6 ± 19.9	31.4 ± 18.6	32.8 ± 19.1
Total procedure times (in minutes)	29.1 ± 18.3	37.6 ± 19.9	31.4 ± 18.6	p = 0.20
Total volume of fluid instilled (in mL)	3170.3 ± 3047.0	3500.3 ± 4282.5	4805.3 ± 5196.5	3829 ± 4289.8
Total volume of fluid instilled (in mL)	3170.3 ± 3047.0	3500.3 ± 4282.5	4805.3 ± 5196.5	p = 0.30
Temperature of instilled fluid (in °C)^a	20.7 ± 1.1	31.4 ± 3.1	34 ± 3.6	28.8 ± 6.4
Temperature of instilled fluid (in °C)^a	20.7 ± 1.1	31.4 ± 3.1	34 ± 3.6	p = 0.00
Pressure of instilled fluid (in mmHg)^b	72.7 ± 6.5	76.1 ± 9.0	71.1 ± 7.6	73.4 ± 8.0
Pressure of instilled fluid (in mmHg)^b	72.7 ± 6.5	76.1 ± 9.0	71.1 ± 7.6	p = 0.05
Total volume of fluid deficits (in mL)	617.9 ± 926.7	443.2 ± 661.7	532 ± 493.9	529.1 ± 708.8
Total volume of fluid deficits (in mL)	617.9 ± 926.7	443.2 ± 661.7	532 ± 493.9	p = 0.60
Core body temperatures (in °C)^c
Preprocedures (at T2)	36.6 ± 0.5	36.6 ± 0.6	36.6 ± 0.6	36.6 ± 0.5
Preprocedures (at T2)	36.6 ± 0.5	36.6 ± 0.6	36.6 ± 0.6	p = 0.90
Postprocedures (at T3)	35.6 ± 0.7	35.9 ± 0.6	35.8 ± 0.7	35.8 ± 0.6
Postprocedures (at T3)	35.6 ± 0.7	35.9 ± 0.6	35.8 ± 0.7	p = 0.27
Pain (VAS scores^d)
Preoperative units	1.9 ± 2.4	1.6 ± 2.1	1.1 ± 1.9	1.5 ± 2.1
Preoperative units	1.9 ± 2.4	1.6 ± 2.1	1.1 ± 1.9	p = 0.36
Postoperative units	1.2 ± 1.4	1.9 ± 1.6	1.3 ± 1.6	1.5 ± 1.6
Postoperative units	1.2 ± 1.4	1.9 ± 1.6	1.3 ± 1.6	p = 0.21

Data are mean ± standard deviation, or n (%). Significant results are bolded.

Temperature as digitally recorded by the automated Thermedx^® FluidSmart™ Fluid Management System (Allen Medical system at the conclusion of the case.

Missing data points, n = 89.

Differences in near-core body temperature at timepoint 3 when immediately after procedures concluded compared to timepoint 2 when immediately prior to procedure start times.

VAS score = visual analogue scale with scale from 0 to 10 where 0 is no pain and 10 is the worst pain imaginable.

POC, products of conception; T, timepoint; VAS, visual analogue score.

As expected, there was a statistically significant difference (p ≤ 0.0001) in the hysteroscopic-fluid temperatures among the 3 arms of the trial, as automatically calculated at the conclusion of each case by the fluid-management system; fluid temperature in group 1 (room-temperature fluid bags) was an average 20.7°C, group 2 (fluid bags pulled from the warming cabinet) was an average 31.4°C, and group 3 (continuously warmed fluid using the automated warming function) was an average 34.0°C. Comparing among the 3 groups, showed that there were no statistically significant differences in procedure lengths (mean of 33 minutes, with a range of 7–88 minutes), volumes of hysteroscopic fluid instilled, or total hysteroscopic fluid deficits, while the average pressure of hysteroscopic fluid instilled approached significance (p = 0.05; Table 1).

The patients had an overall decrease of 0.6°C in near-core body temperatures as assessed by the difference in near-core body temperatures from procedure start (T2, mean: 36.6°C) to procedure end (T3, mean: 35.8°C; Table 1). There were no statistically significant differences in the primary outcome of near-core body temperature or in the secondary outcome of self-rated pain scores among the 3 groups (Table 2).

Table 2.

Difference in Near-Core Body Temperature & Self-Rated Pain

Changes	Room-temperature fluid (group 1, n = 29)	Warming-cabinet fluid (group 2, n = 31)	Continuously warmed fluid (group 3, n = 30)	p-Value
Average change in temperature (in °C)^a	−1.0 ± 0.74	−0.7 ± 0.58	−0.75 ± 0.67	p = 0.29
Average change in pain (on VAS score)^b	−0.6 ± 1.6	0.3 ± 2.3	0.2 ± 1.3	p = 0.09

Difference in near-core body temperatures at timepoint 3 when immediately after procedures concluded, compared to timepoint 2 when immediately prior to procedure start times.

Differences in self-rated VAS pain scores in postoperative units compared to preoperative units.

VAS, visual analogue scale.

When stratifying the data by procedure type (hysteroscopic myomectomy, compared with all other hysteroscopic procedures) there were no differences in near-core body temperatures among the 3 groups (Table 3). However, there was a statistically significant higher average fluid deficit in the hysteroscopic myomectomy procedures, compared with all other surgical procedure types in group 1 (room-temperature fluid bags) and group 2 (fluid bags pulled from the warming cabinet), but not in group 3 (continuously warmed fluid using the automated warming function; Table 3). Similarly, when comparing myomectomies to other surgical procedure types, myomectomies took longer on average than other procedure types in groups 1 and 2, but not in group 3. There was a statistically significant difference in total procedure times for group 2 (46.0 ± 19.1 minutes for myomectomy versus 30.8 ± 18.3 minutes for other procedure types) and approaching significance in group 1 (36.5 ± 20.6 minutes for myomectomy versus 23.1 ± 14.1 minutes for other procedure types). Notably, in group 3 (continuously warmed fluid), when comparing hysteroscopic myomectomy with other hysteroscopic procedure types, there were no differences noted in fluid deficits (658.7 ± 461.3 minutes versus 28.6 ± 19.1 minutes, respectively) and operative times (34.2 ± 18.3 minutes versus 28.6 ± 19.1 minutes, respectively; Table 3).

Table 3.

Average Differences in Near-Core Body Temperatures, Fluid Deficits, & Procedure Times Stratified by Myomectomy, Compared to All Other Procedure Types

Surgical details	Room temperature fluid (group 1, n = 29)		Warming-cabinet fluid (group 2, n = 31)		Continuously warmed fluid (group 3, n = 30)
Average difference in core body temperature (in °C)^a
Myomectomy	−1.2 ± 0.7	p = 0.29	−0.6 ± 0.6	p = 0.34	−0.8 ± 0.6	p = 0.61
All other procedure types	−0.9 ± 0.8	p = 0.29	−0.8 ± 0.6	p = 0.34	−0.7 ± 0.7	p = 0.61
Average fluid deficits (in mL)
Myomectomy	1079.2 ± 1221.2	p = 0.01	749.3 ± 881.0	p = 0.02	658.7 ± 461.3	p = 0.16
All other procedure types	243.1 ± 274.9	p = 0.01	191.2 ± 202.4	p = 0.02	405.3 ± 508.1	p = 0.16
Total procedure times (in minutes)
Myomectomy	36.5 ± 20.6	p = 0.05	46.0 ± 19.1	p = 0.03	34.2 ± 18.3	p = 0.42
All other procedure types	23.1 ± 14.1	p = 0.05	30.8 ± 18.3	p = 0.03	28.6 ± 19.1	p = 0.42

Bolding represents significant results.

Differences in near-core body temperatures at timepoint 3 when immediately after procedures concluded, compared to timepoint 2 when immediately prior to procedures started.

Discussion

In the analysis of the primary outcome of near-core body temperature in patients undergoing operative hysteroscopy procedures, there was no difference that reached statistical significance between the 3 groups of hysteroscopic-fluid temperatures. Average ∂ change in temperature for each group was a negative value, reflecting that patients become colder at the conclusion of the procedures, compared to the initial temperatures taken at the start of the procedures.

At the Newton-Wellesley Hospital, there is no universal protocol regarding use of forced-air patient-warming devices during operative hysteroscopy procedures, and use of the devices is dependent on the anesthesia team of the day. For this reason, the surgical-standardization protocol detailed that a forced-air patient-warming system not be utilized with the intent of avoiding confounding the accurate measurement of the primary outcome of near-core body temperature. The current authors suspect that the overall decrease in patients' temperatures was due to avoidance of the forced-air warming system, coupled with the inherently cold ambient temperature of the OR, which contributed to a further decrease in the patients' near-core body temperatures. As a result, after the downward trend in temperatures was noted at the run-in of 10 patients enrolled, a protocol change was submitted through the IRB to place 3 warm blankets over the torso instead of 1 blanket; this submission was approved.

The risk of perioperative hypothermia persisted when not utilizing the forced-air warming device for continuous production of heat, despite relatively short hysteroscopic procedure times and the use of 3 warm blankets. The consistent trend of decreasing near-core body temperatures up to 1°C suggests that use of the forced-air patient-warming device should be implemented universally as the standard of care as a tool to prevent perioperative hypothermia in all operative hysteroscopy patients undergoing IV sedation in the OR.

In the analysis of the secondary outcome of postoperative pain scores in patients undergoing operative hysteroscopy procedures, there was no difference that reached statistical significance among the 3 groups of hysteroscopic-fluid temperatures.

A limitation of this study for assessment of postoperative pain scores was the surgical setting in which patients underwent IV anesthesia, biasing results to the null. A follow-up study of a cohort of patients who received oral analgesics alone only would be recommended to evaluate this subgroup further, although an oral pain-management regimen would only be applicable for resection of small type 0 submucosal myomas and is not a practical analgesic approach for the majority of resectoscopic procedures.

Concern for fluid deficit is often the limiting factor in completing hysteroscopic myomectomy procedures successfully.¹⁰ Injection of vasopressin is an evidence-based approach to decreasing fluid absorption during resectoscopic surgery,^11–13 with a presumed mechanism of action through stimulating contractions of vascular smooth muscle.¹⁴ Albeit uncommon, there are significant potential systemic side-effects, including hypotension, bradycardia, cardiovascular collapse due to peripheral and pulmonary vasoconstriction, myocardial infarction, pulmonary edema, and death¹⁵; thus it is recommended that vasopressin be diluted to a concentration between 0.05 μ/mL and 0.3 μ/mL.

Most notably, a decrease in the total volume of fluid deficit was achieved in group 3 of this study via a simple intervention of continuously warming the normal-saline hysteroscopic distention medium to 40°C, with no known associated negative side-effects. This is shown in Table 3 with the continuously warmed fluid patients (group 3) having no statistically significant difference between volume of fluid deficit between myomectomy and all other procedure types; whereas statistically significant differences in fluid deficits were seen in groups 1 and 2 with room-temperature fluid bags and fluid bags pulled from the warming cabinet, respectively. This finding held true although being there were no statistically significant differences in total procedure times between the myomectomy procedures and all other surgical procedure types within group 3. The current authors theorize that the significant decrease in fluid deficit associated with the continuously warmed fluid utilized in group 3 may be due to stimulated contraction of the vascular smooth muscle, thereby reducing intravascular absorption of the fluid-distention medium.

Among other factors, overall operative time is critically important when considering risk of fluid overload for resectoscopic surgery. Conventionally, myomectomy procedures have overall longer operative times, compared to polypectomy, metroplasty, and lysis of adhesions, etc. Several studies have reported that use of commercially available hysteroscopic tissue morcellators, such as the Truclear™ (Medtronic, Minneapolis, MN) and MyoSure™ (Hologic, Marlborough, MA) reduce operative time when performing myomectomy and polypectomy, and thereby would reduce fluid deficit and associated risk of overload. However, the clear disadvantage of the hysteroscopic tissue morcellators is their limited use in complete resections of type 2 submucosal myomas as well as significantly higher costs compared to those incurred by resectoscopic surgery.

In the current study, total operative times for myomectomy procedures decreased significantly and approached the total operative times for all other procedure types via the simple intervention of continuously warming the normal saline hysteroscopic distention medium to 40°C, with no increase in costs and no limitations in use. The current authors theorize that this significant decrease in operative times associated with the continuously warmed fluid utilized in group 3 might be due to stimulated contraction of the uterine myometrium, thereby extruding the myomas into the surgical fields of view enabling easier and quicker resections, in addition to improving visualization by reducing bleeding secondary to myometrial contractions.

The strengths of this 3-armed, stratified, randomized trial were the simple exploratory study design, large number of patients enrolled, and application of an intervention in each of the 3 study arms that represented the varied practices nationwide. Additionally, this study addressed an important fundamental aspect of performing hysteroscopic surgery, as there are currently no standard guidelines provided by any gynecologic surgical society regarding the recommended temperature of fluid-distention medium utilized during hysteroscopic surgeries. Although this study was not powered to examine differences in fluid deficits or in procedure times, the unexpected findings revealed by subgroup analyses are clinically relevant and highly applicable.

Conclusions

While the 3 interventions of different hysteroscopic-fluid temperatures did not affect near-core body temperature or postoperative pain, the continuously warmed fluid (group 3) intervention did produce significantly decreased hysteroscopic fluid-deficit volumes as well as total operative times for hysteroscopic myomectomy procedures. Compared to other available marketed tools for decreasing fluid deficits and operative times, such as hysteroscopic morcellators, the intervention of continuously warming fluid could offer advantages, as it is simple and safe. Further studies are needed to confirm these results.

Footnotes

Acknowledgment

The first author would like to thank Lauren Thaxton, MD, at the University of Texas at Dell Medical School, Austin, TX, for her assistance in the statistical analysis.

Author Disclosure Statement

No financial conflicts exist for most of the authors. Dr. Isaacson works as a consultant for Karl Storz and is in a speaker's bureau for Richard Wolf Hysteroscopy, Vernon Hills, IL.

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