Effects of different inflatable heater temperature settings on early postoperative recovery after hysteroscopic surgery: a randomized clinical trial

Abstract

To investigate the effect of perioperative temperature settings of an inflatable warming device on postoperative recovery quality in patients undergoing hysteroscopic myomectomy, this randomized controlled trial enrolled 258 patients receiving laryngeal mask general anesthesia at Xuzhou Central Hospital, China, between March 2022 and August 2024. Patients were allocated to perioperative temperature management with an inflatable warming device set to 38 °C (Group L, n = 129) or 43 °C (Group H, n = 129). A total of 211 patients were included in the final analysis after accounting for exclusions. At 24 h postoperatively, the QoR-40 score was significantly higher in Group H compared to Group L (P < 0.05). At baseline (T0), no significant differences in core body temperature, mean arterial pressure (MAP), or heart rate (HR) were observed between groups (P > 0.05). From T1 to T6, Group H exhibited higher and more stable core body temperature, MAP, and HR compared to Group L (P < 0.05). There were no statistically significant differences in QoR-40 scores at 48 h (P > 0.05) or in the incidence of postoperative restlessness, chills, and infection between the two groups. Compared to 38 °C, the perioperative application of a 43 °C inflatable warming device improved early postoperative recovery quality at 24 h in hysteroscopic myomectomy patients without increasing complication risks.

Introduction

Hysteroscopy is a popular minimally invasive procedure¹ in obstetrics and gynecology, known for its low invasiveness, fewer complications, and quick recovery. It’s widely used for diagnosing and treating issues like uterine adhesions, polyps, fibroids², and cervical cancer³. During hysteroscopy, patients can become hypothermic from the cold operating room, fluid irrigation⁴, and anesthesia. This can cause severe blood pressure fluctuations and circulatory issues^5,6. A drop in intraoperative core body temperature can compromise the patient’s endurance to surgical manipulation and elevate the likelihood of complications, including intraoperative restlessness and postoperative infections. Guidelines emphasize that maintaining body temperature during surgery is key to preventing temperature drops and reducing stress reactions⁷. Consequently, proactive measures are essential⁸.

The “Hypothermia: Prevention and Management in Adults Undergoing Surgery” guidelines by the National Institute for Health and Care Excellence (NICE) suggest that prior to surgery, it’s crucial to assess patients for risk factors of intraoperative hypothermia, including major procedures, open surgeries, prolonged surgery times, and combined general and regional anesthesia⁹. For these patients, using forced-air warmers during surgery is advised to prevent temperature loss and keep core body temperature stable. Many thermoregulation tools are used in surgery, like intravenous fluid warmers, forced-air systems and so on. A study found that cold intravenous fluid fluids can cause hypothermia. Using intravenous fluid warmers keeps fluid temperature steady, lessening the drop in patients’ body temperature during surgery¹⁰. Nonetheless, it is ineffective in regulating the temperature of the surgical site and fails to ensure overall thermal stability for patients. Particularly in cases of significant heat loss at the surgical site, it struggles to adequately prevent a decline in body temperature. And a single study showed an electric heating humidifier can keep elderly patients warm during surgery but may increase skin humidity, making surgery harder. Its small contact area with the skin, especially under body weight, could cause local circulation problems, not effectively warming the body, and risks heat-induced pressure sores¹¹. Furthermore, another study indicated that temperature-controlled blankets may have electromagnetic interference leading to malfunctions and patient burns, thus reducing their safety¹². Notablely, the Forced-air warming system (FAW) is favored by experts and is the only NICE guideline-recommended method for preventing hypothermia during surgery. And one research has demonstrated that using FAW can significantly reduce the risk of hypothermia during the surgery¹³.

Currently, when using forced-air warming devices for thermoregulation, the two most commonly employed temperature settings are 38 °C and 43 °C. While both are used clinically, considerable uncertainty remains regarding which temperature provides superior patient outcomes, particularly in hysteroscopic myomectomy—a procedure associated with substantial fluid-mediated heat loss. To address this evidence gap, we conducted a randomized controlled trial specifically designed to compare the effects of these two temperature settings (38 °C vs. 43 °C) on postoperative recovery in patients undergoing hysteroscopic myomectomy.

Methods

Study design and patient enrollment

This research was granted ethical approval by the Medical Ethics Committee of Xuzhou Central Hospital, China (approval number: XZXY-LK-20211209-049) and is registered with the Chinese Clinical Trial Registry (registration number ChiCTR2200056384, registered on 04/02/2022). All participants provided written informed consent. The study procedures were conducted in line with applicable guidelines and regulations.

With the authorization of the hospital’s Medical Ethics Committee and following the acquisition of patients’ written consent, we conducted hysteroscopic submucosal myomectomies on 258 female patients between March 2022 and August 2024. The inclusion criteria for the patients were as follows: age ranging from 25 to 55 years; a Body Mass Index (BMI) of 18 to 25 kg/m²; a preoperative normal body temperature; administration of laryngeal mask intravenous general anesthesia; and an American Society of Anesthesiologists (ASA) physical status classification of I-II.

All participants were devoid of severe cardiac arrhythmias, major liver or kidney dysfunction, and had no past history of psychiatric disorders. The criteria for exclusion were as follows: preoperative body temperature falling below 36.2 °C or exceeding 37.3 °C; surgical duration of under 15 min or over 60 min; coexistence of conditions that disrupt thermoregulation, such as dysfunctions of the thyroid gland, autoimmune disorders, genital infections, acute or chronic pelvic inflammatory disease, precancerous changes, or pregnancy. The research population included 258 female patients. Patients were randomly assigned to two groups in the order of treatment, with 129 patients in each group: Group L at a temperature of 38 °C and Group H at 43 °C (see Fig. 1). Within Group L, data from 105 cases were analyzed after excluding 11 patients who required a change in anesthesia due to prolonged surgery and 13 patients who were not followed up postoperatively. In Group H, data from 106 cases were analyzed following the exclusion of 12 patients for the same reason as in Group L and 11 patients who were lost to follow-up. In sum, the study compiled data from a total of 211 cases.

Fig. 1.

Flow of participants through the study.

Randomization and blinding

The SPSS software version 26.0 (IBM Corp.) was used to generate random assignments at a 1:1 ratio. Sequentially numbered opaque envelopes contained the allocation results. Upon patient enrollment, non-trial staff opened the envelopes in sequential order and configured the inflatable heater to the assigned temperature (38 °C for Group L or 43 °C for Group H) according to the revealed allocation.The investigator in charge of data collection and postoperative follow-up was blinded to the group assignment. Due to the nature of the intervention (different heater temperatures), it was not feasible to blind the attending anesthesiologists or the patients to the group allocation. However, the outcome assessor remained blinded throughout the study.

Research protocol

Upon arrival in the operating room, patients in both groups received standard intravenous access and were administered lactated Ringer’s solution at 10 mL/kg/h. Vital signs and hemodynamic parameters were monitored using a Philips monitor, with an oral probe continuously tracking core body temperature. An inflatable heater (Maikang Medical Warming Blanket, PW-I) was deployed for warmth. This was the only interventional difference between groups; it was set at 38 °C for Group L and 43 °C for Group H. To ensure uniform and consistent application, the blanket was positioned according to the manufacturer’s guidelines to cover the patient’s upper body (chest and arms). The same model of heater was used for all patients, and its application was supervised by trained research staff to maintain consistency throughout the study. All other aspects of perioperative care, including anesthesia protocol, surgical technique, operating room environment, and postoperative analgesia, were identical between the two groups. During induction, patients were covered by the heater. Pre-anesthesia, patients inhaled oxygen (6 L/min) and were induced with remimazolam (0.1 mg/kg), propofol (2 mg/kg), and oxycodone (0.1 mg/kg), followed by laryngeal mask placement.

Anesthesia was maintained with a continuous infusion of propofol (4–8 mg/kg/h) and remifentanil (0.1 µg/kg/min) throughout surgery. The operation was performed with the patient in the lithotomy position. The operating room was kept at 22 °C with 55–60% humidity. Irrigation fluids and electrocautery solutions were heated to 32–36 °C. The heater covered non-surgical areas, and skin was monitored for abnormalities. Postoperative analgesia included flurbiprofen axetil (50 mg) administered intravenously. After surgery, patients remained covered with the heater and were moved to the PACU. Core body temperature, mean arterial pressure (MAP), and heart rate (HR)were recorded at T0 (entering the OR), T1 (operation start), T3 (15 min into surgery), T4 (30 min into surgery), T5 (operation end), and T6 (return to ward).

Throughout the surgical procedure, the following adverse events were observed, along with their respective treatments: For cases of hypotension, defined as a 20% decrease from baseline systolic blood pressure or a systolic pressure below 90 mmHg, 50 µg of phenylephrine was administered. In instances of bradycardia, where the heart rate fell below 50 beats per minute, 0.5 mg of atropine was administered.

The postoperative complications were defined as follows: Postoperative restlessness was identified by neurological and motor restlessness in a state of reduced consciousness, assessed by a Richmond Agitation and Sedation Scale (RASS) score of ≥ 1 point¹⁴. Postoperative shivering was evaluated using the Bedside Shivering Assessment Scale (BSAS) and was considered present at a grade of ≥ 1 level¹⁵. Postoperative infection was diagnosed based on symptoms such as elevated body temperature, abdominal pain, abnormal vaginal secretion odor, or the presence of purulent secretions, and was confirmed by the culture and identification of secretions.

Outcomes

Primary outcome: QoR-40 score at 24 h postoperatively.

Secondary outcomes: QoR-40 score at 48 h postoperatively; comparisons of core body temperature and hemodynamic parameters (MAP, HR) between groups at predefined timepoints (T0–T6); incidence of postoperative complications (Postoperative restlessness, Postoperative chills, Postoperative infection).

Sample size

Based on our prior research, the standard deviation (SD) for the postoperative QoR-40 score in patients undergoing elective hysteroscopic surgery is 22. Drawing from the existing literature, the minimum clinically important difference (MCID) for the QoR-40 is 10¹⁶. Sample size calculation was conducted using PASS 21.0 software, with a targeted test power of 90% and a significance level of 0.05. The calculation determined that 103 cases were required for each group. Accounting for a potential 20% dropout rate, the final sample size was set at 129 cases per group, totaling 258 cases.

Statistical analysis

All analyses were performed based on the intention-to-treat principle, including all randomized patients who provided data for the given endpoints. Statistical analyses were conducted on demographic data, perioperative variables, and both primary and secondary outcomes for each study group. The normality of the distribution for quantitative variables was assessed using the Kolmogorov-Smirnov test. Quantitative variables, including the primary outcome (QoR-40 score), were analyzed using either the Mann-Whitney U test or the independent-samples t-test, depending on the distribution of the data. For the primary outcome (24-hour QoR-40 score), an analysis of covariance (ANCOVA) was additionally performed to adjust for potential confounding effects of body mass index and history of hysteroscopic procedures. Nominal variables were described using frequencies (percentages), while continuous variables were presented as mean ± standard deviation (SD) or median (interquartile range, 25th-75th percentiles). Given the multiple comparisons performed for secondary outcomes (measurements across timepoints and complications), the Bonferroni correction was applied where appropriate. A P-value of less than 0.05 was deemed statistically significant. All statistical analyses were performed using SPSS 26.0 software. Graphs were generated using GraphPad Prism version 10.1 for Windows.

Results

The trial was carried out from March 2022 to August 2024. We screened and included 211 eligible patients in the final analysis (see Fig. 1). The demographic characteristics of the patients in the two groups were comparable, with no statistically significant differences observed (P > 0.05) (refer to Table 1). Data are presented as mean ± standard deviation or the number of cases. No significant differences were found between the two groups with respect to age, ASA classification, body mass index (BMI), and history of intrauterine procedures.

Table 1.

Demographic data.

Group	Number of cases (n)	Age (years)	BMI	ASA (I/II)	HPH (0 times/≥1 times)
L	105	43.4 ± 5.3	20.5 ± 1.9	87/18	13/92
H	106	42.9 ± 4.5	21.0 ± 1.6	92/14	17/89
P value		0.27	0.17	0.42	0.44

BMI: Body mass index, HPH: hysteroscopic procedure history.

The mean QoR-40 score at 24 h was significantly higher in Group H (182.4) than in Group L (172.9), with a mean difference of 9.5 (95% CI: 7.2 to 11.8; P < 0.001). This significant difference persisted after adjustment for body mass index and history of hysteroscopic procedures using analysis of covariance (F(1, 207) = 25.30, p < 0.001). In contrast, at 48 h postoperatively, there was no significant difference in QoR-40 scores between groups (192.6 vs. 191.4 for Groups H and L, respectively; P > 0.05) (refer to Table 2).

Table 2.

QoR-40 score.

Item	Group	Emotions	Comfort	Independence	Support	Pain	Total score
POD-1	L	41.1 ± 2.2	47.3 ± 4.5	18.8 ± 2.5	30.8 ± 1.3	33.5 ± 2.1	172.9 ± 7.8
	H	42.9 ± 2.4	55.7 ± 3.9*	18.7 ± 2.1	31.7 ± 1.6	33.4 ± 2.7	182.4 ± 8.5*
POD-2	L	42.5 ± 0.8	55.7 ± 2.3	21.4 ± 3.2	32.6 ± 0.8	34.9 ± 1.4	191.4 ± 3.5
	H	43.2 ± 0.3	57.6 ± 2.5	23.4 ± 3.1	33.4 ± 0.4	35.0 ± 2.1	192.6 ± 4.4

POD-1: Postoperative Day 1, POD-2: Postoperative Day 2; *P < 0.05.

The QoR-40 scores at 24 h postoperatively were significantly higher in Group H compared to Group L (P < 0.05). The mean QoR-40 score for patients in Group H at 24 h was 182.4, whereas for patients in Group L, it was 172.9. At 48 h postoperatively, the mean QoR-40 score for Group H was 192.6, and for Group L, it was 191.4. Although the mean QoR-40 score for Group H was slightly higher than that of Group L at this time point, the difference was not statistically significant (P > 0.05).

At the initial time point (T0), the core body temperatures of the two groups were comparable (P > 0.05). From T1 through T6, Group H maintained higher core body temperatures compared to Group L. In Group L, core body temperatures at each subsequent time point (T1 to T6) were significantly lower than at T0 (P < 0.05). In Group H, the core body temperature at T0 and T1 did not differ significantly (P > 0.05). However, from T2 to T6, the core body temperatures in Group H were lower than those at T0 and T1, although this decrease was statistically significant (P < 0.05). The range of fluctuation in core body temperature for Group H was less pronounced than that for Group L, and this difference was statistically significant (P < 0.05) (refer to Fig. 2).

Fig. 2.

Core body temperature. T0 (entering the OR), T1 (operation start), T2 (5 min into surgery), T3 (15 min into surgery), T4 (30 min into surgery), T5 (operation end), and T6 (return to ward). ℃: Core body temperature; *P < 0.05. At the initial time point (T0), the core body temperatures of the two groups were comparable (P > 0.05). From T1 through T6, Group H maintained higher core body temperatures compared to Group L. In Group L, core body temperatures at each subsequent time point (T1 to T6) were significantly lower than at T0 (P < 0.05). In Group H, the core body temperature at T0 and T1 did not differ significantly (P > 0.05). However, from T2 to T6, the core body temperatures in Group H were lower than those at T0 and T1, although this decrease was statistically significant (P < 0.05). The range of fluctuation in core body temperature for Group H was less pronounced than that for Group L, and this difference was statistically significant (P < 0.05).

At the baseline time point (T0), the mean arterial pressure (MAP) and heart rate (HR) for both groups were equivalent (P > 0.05). From T1 to T6, the MAP and HR in both groups showed decreases compared to the levels at T0, and these differences were statistically significant (P < 0.05). During the period from T1 to T6, Group H exhibited higher MAP values compared to Group L. Similarly, the HR in Group H was higher than that in Group L from T1 to T5, with this difference reaching statistical significance (P < 0.05). The fluctuations in both MAP and HR for Group H were less pronounced than those for Group L, and this difference in the range of fluctuation was statistically significant (P < 0.05) (see Fig. 3).

Fig. 3.

Hemodynamic data. T0 (entering the OR), T1 (operation start), T2 (5 min into surgery), T3 (15 min into surgery), T4 (30 min into surgery), T5 (operation end), and T6 (return to ward). MAP: mean arterial pressure; HR: heart rate ; *P < 0.05. At the baseline time point (T0), the mean arterial pressure (MAP) and heart rate (HR) for both groups were equivalent (P > 0.05). From T1 to T6, the MAP and HR in both groups showed decreases compared to the levels at T0, and these differences were statistically significant (P < 0.05). During the period from T1 to T6, Group H exhibited higher MAP values compared to Group L. Similarly, the HR in Group H was higher than that in Group L from T1 to T5, with this difference reaching statistical significance (P < 0.05). The fluctuations in both MAP and HR for Group H were less pronounced than those for Group L, and this difference in the range of fluctuation was statistically significant (P < 0.05).

Regarding postoperative complications, Group H experienced 1 case of postoperative shivering and 1 case of postoperative infection. In Group L, there was 1 case of postoperative shivering. No other adverse events or harms related to the use of the inflatable heater at either temperature setting were observed throughout the study period. There was no statistically significant difference in the overall incidence of complications between the two groups (P > 0.05).

Discussion

The QoR-40 scores for patients in Group H were significantly higher compared to Group L at 24 h postoperatively (P < 0.05), although no significant difference was observed between the groups at 48 h postoperatively (P > 0.05). The observed mean difference of 9.5 points in the 24-hour QoR-40 score between groups approaches the established MCID of 10 for the QoR-40 scale¹⁶ suggesting that the improvement with the 43 °C setting is not only statistically significant but also approaches clinical importance. Subsequent analysis revealed that patients in Group H had notably better scores in the dimensions of physical comfort support compared to Group L. This indicates that the use of the inflatable heater can markedly enhance the early postoperative recovery quality for patients undergoing hysteroscopic surgery, with a particularly pronounced effect on improving physical comfort¹⁷.

The beneficial effect on recovery quality was observed at 24 h but not sustained at 48 h. This suggests that the advantage of the higher warming temperature is most impactful in the immediate postoperative period. This transient effect is likely because the primary physiological challenge—intraoperative hypothermia and its hemodynamic consequences—occurs during and shortly after surgery. By 48 h, most patients, regardless of group, have regained normothermia and stabilized hemodynamically, leading to similar overall recovery scores. The early enhancement in physical comfort and physiological stability, however, remains a valuable outcome for patient comfort¹⁸.

For the improved postoperative recovery observed in Group H, which used the inflatable heater set to a higher temperature, there may be two potential reasons. Firstly, in this study, both Group L (with a temperature setting of 38 °C) and Group H (with a temperature setting of 43 °C) demonstrated effectiveness in preventing hypothermia during surgery. However, the data revealed that when the temperature was set at 43 °C, as opposed to 38 °C, the decline in intraoperative core body temperature was less severe, and the fluctuation of intraoperative core body temperature was reduced. The rationale for this difference can be attributed to several factors. Patients undergoing surgery often experience a decrease in core body temperature due to the inhibitory effects of intravenous anesthetic drugs on thermoregulation, combined with environmental conditions such as operating room temperature and humidity, skin disinfection, and the infusion of distending fluids^19,20.

In this study, an inflatable heater was used to maintain peri-operative body temperature. The heater covered the patient’s entire body from the time they entered the operating room until they left, using a high-convective gas at a specific temperature to elevate the body surface temperature. The high wind speed provided by the heater helped to quickly counteract the cooling effects of the operating room environment and intravenous anesthesia, minimizing the drop in core body temperature.

The results indicated that patients in Group L experienced an immediate decrease in core body temperature at the start of the operation (T1), while Group H maintained a more stable core body temperature. This is likely because the 38 °C setting of the inflatable heater in Group L was insufficient to compensate for the rapid loss of body heat once the operation began. In contrast, the 43 °C setting in Group H was higher than the normal human core body temperature range and could more effectively raise the body surface temperature, counteracting the heat loss from anesthesia and respiration, and better managing the thermal stress caused by the surgical procedure and distending fluids. By setting the inflatable heater to 43 °C, it was possible to elevate and stabilize the core body temperature more effectively, thereby enhancing physical comfort for patients postoperatively. This suggests that a higher temperature setting for the inflatable heater may be a more advantageous strategy for maintaining intraoperative thermal homeostasis and improving patient recovery outcomes.

Secondly, in the study, the mean arterial pressure (MAP) and heart rate (HR) for both groups were lower at T1 to T6 compared to T0 (P < 0.05), likely due to the depressant effect of intravenous anesthetic drugs on the circulatory system. This physiological response is advantageous as it helps control hemodynamic disturbances that can be induced by surgical stress, enhancing the safety of the procedure. However, unplanned hypothermia during surgery can negatively impact platelet function, inhibit coagulation, increase bleeding, and reduce effective circulating blood volume, leading to hypotension. Group H, which used the inflatable heater set at 43 °C, maintained higher MAP and HR levels during surgery compared to Group L (set at 38 °C) (P < 0.05), with a smaller fluctuation range (P < 0.05). This suggests that setting the inflatable heater at 43 °C can partially counteract the circulatory depression caused by anesthetic drugs and better stabilize hemodynamic levels intraoperatively²¹.

Hypothermia is known to decrease baroreceptor sensitivity, reduce cardiac output, and cause electrophysiological changes that can lead to bradycardia and arrhythmias. It also induces aortic vasodilation, which can result in peripheral hypotension as the body attempts to maintain myocardial blood supply. Elevating the core body temperature can reverse these effects, increasing circulation, heart rate, and blood pressure²². The use of the inflatable heater at 43 °C during hysteroscopic surgery helps to mitigate the cooling effect of the operating room environment, compensates for the decrease in MAP and HR caused by general anesthesia, and maintains organ tissue perfusion. This improves the patient’s tolerance to surgical stress and preserves hemodynamic stability, which is beneficial for a quicker postoperative recovery.

The study found that the incidence of postoperative complications, includ12ing shivering and infection, was similar between Group H (43 °C setting) and Group L (38 °C setting), with no statistically significant difference in the overall complication rates (P > 0.05). While Group H had a numerically higher incidence of complications, the low frequency of these events in both groups makes it inconclusive whether the higher temperature setting increases the risk of postoperative infection.

In summary, the study suggests that maintaining a stable core body temperature and hemodynamic indicators during hysteroscopic surgery is beneficial for postoperative recovery. Setting the inflatable heater at 43 °C appears to further improve the early postoperative recovery quality compared to the 38 °C setting, particularly in terms of physical comfort and psychological support.

Limitations

This study has several limitations. First, as a single-center study conducted at Xuzhou Central Hospital, the generalizability and external validity of the findings may be limited. Furthermore, the exclusion of patients with a BMI outside the 18–25 kg/m² range may limit the generalizability of our findings, particularly as overweight and obese patients often present with distinct thermoregulatory challenges that could influence their response to active warming strategies. Although the trial adopted a randomized design, blinding of both patients and operators was not implemented due to the difficulty in masking the temperature of the heating device, which may introduce operational and assessment biases. Furthermore, the relatively strict inclusion criteria (e.g., ASA class I–II and specific BMI range) may also limit the extrapolation of the conclusions to broader populations.

Furthermore, while no thermal injuries or other serious adverse events were observed in either group, the sample size of this study may be insufficient to definitively rule out rare complications associated with the use of a 43 °C forced-air warming device. Moreover, this study primarily relied on the QoR-40 questionnaire to evaluate recovery quality and did not encompass long-term recovery outcomes, cost-effectiveness analyses, or more in-depth patient-reported experiences. Future studies should aim to validate the efficacy and safety of the forced-air warming system in hysteroscopic surgery through larger sample sizes, multicenter collaboration, and the inclusion of more diverse patient populations, thereby enhancing the comprehensiveness and practical applicability of the evidence.

Conclusions

The perioperative application of an inflatable heater set at 43 °C improved the postoperative 24-hour recovery quality score for patients undergoing hysteroscopic myomectomy, without increasing the risk of complications, when compared to a setting of 38 °C.

Author contributions

All authors made substantial contributions to the design of this study, dataacquisition and interpretation, statistical planning, drafting of the manuscript, or critical revision of the manuscript. All authors agree to be accountable forall aspects of the work and have approved the final version of the manuscriptfor submission.

Funding

This research was funded by Xuzhou Medical Young Reserve Talent Program (No. XWRCHT20220017). The funding body had no role in the design of the study; the collection, analysis, or interpretation of the data; or the writing of the manuscript.

Data availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Competing interests

The authors declare no competing interests.

Ethics approval

This study was approved by the Medical Ethics Committee of Xuzhou Central Hospital in China (XZXY-LK-20211209-049) and registered in the Chinese Clinical Trial Registry (ChiCTR2200056384, 04/02/2022). It adhered to the principles outlined in the Declaration of Helsinki and the CONSORT 2010 guidelines. Informed consent for study registration and anonymous data collection and publication was obtained from all patients.