Abstract
Introduction and aims
Blood loss is a common side-effect in orthognathic surgery. Deliberated hypotensive anaesthesia can reduce blood loss. The purpose was to evaluate the effect of add-on dexmedetomidine compared with the usual hypotensive drug bolus on blood loss and patient outcomes in orthognathic surgery.
Methods
This double-blinded randomised controlled trial study was conducted on patients with American Society of Anaesthesiology class I or II, and 18 to 45 years-old, scheduled for bimaxillary orthognathic surgery. Patients were randomly divided into 2 groups: study (add-on dexmedetomidine; D group) and control (usual bolus of the hypotensive drug; C group) by block randomisation. The primary outcome variables were blood loss, postoperative haemoglobin, and incidence of intraoperative blood transfusion. The secondary outcome variables were the stability of the vital signs, overall pain score and opioid requirement, anaesthetic time, quality of the operative visual field, surgeons’ satisfaction, hospital stay length and side effects. Statistical significance was defined as P-value <.05.
Results
The sample was composed of 60 patients with a mean age of 25.93 (4.66) years and 26 (43.30%) were male. The blood loss for D and C groups was 401.67 (131.62) and 898.33 (548.58) mL, respectively (P < .001). The D group demonstrated a significantly lower overall pain score 2.43 (1.36) versus 4.10 (1.19) for C group. The quality of the surgical field using Fromme's scale was significantly higher in D group 0.93 (0.83) versus 2.53 (0.94). Nausea/vomiting was also significantly lower in D group.
Conclusions
Adding-on dexmedetomidine in orthognathic surgery decreases blood loss and improves patient outcomes, especially in overall pain score, quality of the surgical field, and incidence of nausea/vomiting.
Clinical relevance
Dexmedetomidine can be considered a safe and effective medication for performing DHA in orthognathic surgery. Adding-on dexmedetomidine significantly reduced estimated blood loss by over 50% and improves patient outcomes.
Keywords: Dexmedetomidine, Surgical blood loss, Orthognathic surgery, Controlled hypotension, Postoperative pain
Introduction
Orthognathic surgery is performed for repositioning the maxilla, mandible, and chin, resulting in a more balanced and proportional face.1 The goals of surgery are to correct the dental occlusion, provide facial balance and improve airway patency in obstructive sleep apnea patients.2 The common complications associated with orthognathic surgery are malocclusion, inferior alveolar nerve injury, bad split, infection, and blood loss.3 A systematic review reported that the mean blood loss from orthognathic surgery was 436.11 ± 207.89 mL.4 The factors that increase blood loss in orthognathic surgery are low body mass index (BMI), more extensive or complicated surgery, such as double-jaw surgery with genioplasty or multi-piece maxillary with mandibular surgery, and prolonged operating time.5 Bleeding in orthognathic surgery can be severe, requiring intraoperative crystalloids, colloids, and/or blood products replacement, which affects the postoperative morbidity and mortality and increases the length of hospital stays.6,7
Deliberate hypotensive anaesthesia (DHA) is a strategy used to reduce blood loss during surgery by which the blood pressure is intentionally and predictably decreased to improve the quality of the surgical field.8 This strategy is effective in orthognathic surgery, especially in maxillary procedures.9,10 A meta-analysis found that hypotensive anaesthesia reduced the mean blood loss by 169 mL in orthognathic surgery and 175 mL in double-jaw surgery.11 For DHA, the mean arterial pressure (MAP) is suggested to be from 50 to 65 mm Hg.10 Others suggest decreasing the MAP 20% to 30% below the baseline MAP with a minimum of 50 mm Hg in healthy adult patients, and 80 mm Hg in elderly patients.11, 12, 13 To prevent the organ hypoperfusion risks during DHA, the modified hypotensive anaesthesia techniques, which result in a minor reduction in MAP, are sometimes applied based on the patient's underlying diseases.14,15 There are various pharmacological agents used to induce hypotension, such as deep inhalational agents, esmolol, labetalol, nicardipine, clonidine, remifentanil and dexmedetomidine (DEX). Previous studies examined the efficacy of these agents in DHA, and the results were good and comparable, with each drug having its own set of advantages and disadvantages.12,16, 17, 18, 19, 20
DEX is a highly selective alpha-2 adrenergic agonist. It possesses sedative, analgesic, dose-dependent sympatholytic and amnestic properties, without respiratory depression. DEX has ischemic and hypoxic injury protective effects, including cardiovascular, neurological and renal protection.21 Therefore, DEX may have beneficial effects in controlling hemodynamics and reducing intraoperative blood loss.
A meta-analysis reported that DEX for DHA decreased blood loss compared with normotensive anaesthesia in orthognathic surgery.11 When DEX was compared with the other pharmacological agents used in the DHA technique, the outcomes usually compared the hemodynamic parameters, the quality of the visual field, operative time, awakening and extubation time, and postoperative pain.16,17,19,20,22 Some of these studies reported outcomes on blood loss, however the bleeding in the DEX group was not significantly different.12,16,20 A retrospective study in orthognathic surgery patients reported that DEX decreased blood loss.23 Therefore, the purpose of this study was to prospectively investigate the effectiveness of DEX on blood loss and patient outcomes in orthognathic surgery. The investigators hypothesised that the DEX could decrease blood loss and improve patient outcomes. The specific aims of this study were to measure and compare: (1) blood loss, postoperative haemoglobin, and incidence of intraoperative blood transfusion, (2) the stability of the vital signs, (3) overall pain score and opioid requirement, (4) anaesthetic time, quality of the operative visual field, and surgeons’ satisfaction; and (5) hospital stay length, side effects from DEX and postoperative nausea and vomiting.
Materials and methods
Study design and sample
This double-blinded, randomised clinical trial was conducted at the Faculty of Dentistry, Chulalongkorn University from September 2023-March 2024. The patients, surgeons, and data collector were blinded to the treatment groups, while the anaesthetic team were not blinded.
The inclusion criteria were the patients with American Society of Anaesthesiology (ASA) class I or II, and 18 to 45 years-old who would be undergoing bimaxillary orthognathic surgery (Le fort I osteotomy and bilateral sagittal split ramus osteotomy (BSSRO) without segmental Le fort, genioplasty, or ancillary procedures) The exclusion criteria were patients with coagulopathy, bradycardia, cardiac dysrhythmias, known allergy to the study drugs, pregnant, or lactating.
The study design was approved by the Human Research Ethics Committee of the Faculty of Dentistry, Chulalongkorn University (HREC-DCU 2023-047). The study's protocol was registered with the Thai clinical trials registry (TCTR20230818002). The study was conducted in accordance with the Declaration of Helsinki. Informed consent was obtained from all participants before enrollment. We used the CONSORT checklist when writing our report.24
Study variables
Independent variable
The independent variable was the medication used to induce hypotension randomly divided into 2 groups: experimental (add-on dexmedetomidine; D group) or control (usual bolus of the hypotensive drug; C group). Randomisation was performed using computerised block randomisation with a block size of 4 and the allocation was concealed in an opaque envelope until the operation time. The patients did not know which group they were assigned to. After induction, without the surgeons in the operating room, the anaesthesia team opened the envelope and prepared the study drugs based on the assigned patient group. The surgeons were invited to the operating room and, thus, blinded to the treatment groups. The D group patients received a 1 mcg/kg DEX bolus over 10 minutes, then infusion at a rate of 0.4 mcg/kg/h until the beginning of suturing. The patients in the C group received normal saline solution (NSS) as a placebo. Both groups received a bolus of 5 mg intravenous labetalol, a hypotensive drug, to maintain blood pressure.
Main outcome variables
The primary outcome variables were blood loss, postoperative haemoglobin, and incidence of intraoperative blood transfusion.
Blood loss: Blood loss was estimated from the blood collected in a suction apparatus subtracted from the total irrigating water plus the weight of the blood-soaked gauzes minus the dry gauzes in grams. (1 gram is equal to 1 mL)
Postoperative haemoglobin: A blood sample for haemoglobin was collected and measured at postoperative day 1.
Incidence of intraoperative blood transfusion: If the estimated blood loss exceeded the allowable blood loss (ABL),25 a packed red cell transfusion was initiated. The ABL, which set the lowest acceptable haematocrit at 30% was calculated preoperatively. Because our dental hospital does not have its own blood bank, the time required for a packed red cell request to arrive at the operating room is ∼60 to 75 minutes, therefore, we set a higher acceptable haematocrit.
The secondary outcome variables were (1) the stability of the vital signs: intraoperative heart rate (HR), intraoperative mean arterial pressure (MAP), the amount of vasopressor used, (2) overall pain score and opioid requirement: intraoperative opioid, postoperative opioid in the recovery room, and the first 24-hours postoperatively, (3) anaesthetic time, quality of the operative visual field, and surgeons’ satisfaction, (4) hospital stay length and side effects: an episode of bradycardia, hypotension, arrhythmia, or nausea/vomiting.
Intra-operative HR and intraoperative MAP: The HR and MAP at the beginning of the Le fort I osteotomy and BSSRO.
Amount of vasopressor used: Total dosage of ephedrine used intraoperatively.
Overall pain score: Overall postoperative pain was assessed by the data collector who was blinded to the treatment groups on postoperative day 1, using a 10-point numerical rating pain scale (0 is no pain and 10 is the worst pain).
Opioid requirement: The amount of intraoperative opioids as morphine milligram equivalents (MME) were recorded. The postoperative morphine consumption in the recovery room and the first 24-hours were retrieved from the intravenous patient control analgesia (IV-PCA) record.
Anaesthetic time: The duration from the start of anaesthesia until the patient was transferred from the operating room.
Quality of the operative visual field: After the operation was finished, the surgeons were interviewed by the data collector who was blinded to the treatment groups regarding the quality of the surgical visual field. Fromme's Ordinal Scale,26 which is a 5-point scale from 0 (no bleeding) to 5 (severe bleeding), was used to represent the quality of the surgical field.
Surgeons’ satisfaction: After the operation was finished, the surgeons were interviewed by the data collector who was blinded to the treatment groups regarding their satisfaction with the surgical visual field. The surgeons’ satisfaction was graded on a 5-point Likert scale, from 1 (very dissatisfied) to 5 (very satisfied).
Hospital stay length: The number of days that the patients stayed in hospital from admission until discharge, including a 1-day preoperative admission.
Side effects: The incidence of side effects from DEX, such as an episode of bradycardia (HR below 50 beats per minutes [bpm]), hypotension (MAP below 55 mm Hg), new arrhythmias, and the incidence of postoperative nausea/vomiting were recorded.
Covariates
The covariates were sex, age, height, weight, body mass index, preoperative haemoglobin, heart rate, and mean arterial pressure.
Protocol
After arriving at the operating room, standard monitoring, such as blood pressure, electrocardiography, and pulse oximetry were applied. General anaesthesia was conducted by an anaesthesiologist using 2 mg/kg intravenous propofol, 1 mcg/kg fentanyl, and 0.15 mg/kg cis-atracurium to facilitate nasotracheal intubation. After induction, the patients in the D group received a 1 mcg/kg DEX bolus in 10 minutes then infusion at a rate of 0.4 mcg/kg/h. The patients in the C group received NSS in the same manner. Intravenous antibiotic prophylaxis drugs (amoxicillin-clavulanic acid 1.2 g or clindamycin 600 mg) and 15 mg/kg tranexamic acid were administered in both groups. Anaesthesia was maintained with 50% nitrous oxide in oxygen, 1% to 2% sevoflurane and cis-atracurium. Ventilation was supported to maintain the end-tidal carbon dioxide (EtCO2) at ∼35 to 40 mm Hg. The MAP was targeted to be within 60 to 75 mm Hg during the operation in both groups. Whenever the MAP was over 75 mm Hg, 25 mcg fentanyl was given intravenously every 10 minutes in 2 consecutive doses. If the MAP was still higher than 75 mm Hg, 5 mg intravenous labetalol, a hypotensive drug, was given. If the MAP was below 60 mm Hg, 6 mg intravenous ephedrine, a sympathomimetic drug, was administered. Both groups underwent Le fort I osteotomy and BSSRO surgery by the same surgery team and received similar standard treatment and monitoring throughout the operation. If the estimated blood loss exceeded the allowable blood loss, a packed red cell transfusion was initiated. The infusion of DEX and placebo were stopped at the start of suturing, and 40 mg Parecoxib and 0.15 mg/kg ondansetron were prescribed intravenously in both groups.
After the operation was finished, the neuromuscular blockage was reversed with 0.05 mg/kg intravenous neostigmine and 0.02 mg/kg atropine. The patients were extubated and transferred to the recovery room for immediate postoperative observation. Both groups received a 1 mg IV-PCA morphine bolus for postoperative pain control, no basal rate, and a 5-minute lockout interval.
Statistical analysis
A priori per-protocol analysis was performed to evaluate the effectiveness of DEX on blood loss and patient outcomes in orthognathic surgery. Only participants who fully adhered to the study protocol and completed the entire intervention were included in the final analysis.
The sample size was calculated by the G*power program version 3.1 using intraoperative blood loss values from a previous study27 based on the hypothesis of 2 independent means with an alpha of 0.05 and 0.8 power for a 2-sided test, which indicated that at least 27 participants per group were required. Considering a potential 10% of subjects dropping out of the study, 30 participants per group (60 participants in total) were recruited for this study.
The data was analysed using IBM SPSS Statistics for Windows, version 29.0 (IBM, Armonk, New York, USA). Descriptive statistics were reported as frequencies and percentages for the categorical variables or means and standard deviations for the quantitative variables. The differences between the D and C groups were analysed using the chi-square test or Fisher's exact test for the categorical variables, as appropriate. The quantitative variables were tested for normality and homogeneity of variances by the Shapiro-Wilk test and Levene's test, respectively. The differences in each quantitative variable between the D and C groups were analysed using the independent t-test or Mann-Whitney U test, as appropriate. Statistical significance was defined at P-value <0.05.
Results
Sixty patients were included in this prospective study and were randomised into the DEX group (D group, n = 30) and the Control group (C group, n = 30). The flow diagram of the study is presented in Figure 1. No harms or adverse effects occurred in both groups. The baseline characteristics of the patients are presented in Table 1. The patients’ age ranged from 19-37 years, with a mean age of 25.93 ± 4.66 years and 26 (43.30%) were male. All participants were in ASA class I or II, with some having dyslipidaemia or mild asthma as comorbidities. There was no significant difference in the baseline characteristics comprising sex, age, height, weight, BMI, preoperative haemoglobin, preoperative MAP, and HR between the D and C groups (P > .05). The mean dosage of labetalol used in the D and C group was 0.67 ± 2.54 and 6.50 ± 5.71 mg, respectively (P < .001).
Figure 1.
The flow diagram of the study.
Table 1.
Bivariate analyses of the covariates versus the treatment group.
| Covariates | Total | D group | C group | P-value |
|---|---|---|---|---|
| (n = 60) | (n = 30) | (n = 30) | ||
| Sex, n (%) | 1.000a | |||
| Male | 26 (43.3) | 13 (43.3) | 13 (43.3) | |
| Female | 34 (56.7) | 17 (56.7) | 17 (56.7) | |
| Age (year), mean ± SD | 25.93 ± 4.66 | 24.87 ± 4.45 | 27.00 ± 4.69 | .076b |
| Height (cm), mean ± SD | 167.15 ± 8.48 | 167.00 ± 8.96 | 167.30 ± 8.12 | .892b |
| Weight (kg), mean ± SD | 64.30 ± 13.21 | 65.48 ± 14.55 | 63.11 ± 11.84 | .492b |
| BMI (kg/m2), mean ± SD | 22.94 ± 3.78 | 23.59 ± 4.17 | 22.29 ± 3.27 | .184b |
| Preoperative haemoglobin (g/dL), mean ± SD |
13.86 ± 1.37 | 14.12 ± 1.32 | 13.59 ± 1.38 | .130b |
| Preoperative MAP (mm Hg), mean ± SD | 76.55 ± 6.02 | 75.70 ± 5.89 | 77.40 ± 6.12 | .278b |
| Preoperative HR (bpm), mean ± SD | 75.50 ± 8.18 | 75.37 ± 8.29 | 75.63 ± 8.20 | .901b |
Abbreviations: BMI, body mass index; C, Control; D, add-on dexmedetomidine; HR, heart rate; MAP, mean arterial pressure; SD, standard deviation.
Differences between groups analysed by the chi-square test.
Differences between groups analysed by the independent t-test.
Significant difference (P < .05) indicated in bold.
The results of the primary outcomes are shown in Table 2. The D group demonstrated a significantly lower estimated blood loss (Figure 2A) compared with the C group. The blood loss in the D and C group was 401.67 ± 131.62 and 898.33 ± 548.58 mL, respectively (P < .001). Postoperative haemoglobin levels (Figure 2B) were significantly higher in the D group (12.82 ± 1.35 g/dL) than those in the C group (11.26 ± 1.41 g/dL) (P < .001). There was no blood transfusion in the D group, while in the C group 36.7% received a blood transfusion.
Table 2.
Bivariate analyses of the treatment group versus blood loss, postoperative haemoglobin, and incidence of intraoperative blood transfusion
| Variable | D group | C group | P-value |
|---|---|---|---|
| (n = 30) | (n = 30) | ||
| Estimated blood loss (mL), mean ± SD | 401.67 ± 131.62 | 898.33 ± 548.58 | <.001a |
| Postoperative haemoglobin (g/dL), mean ± SD | 12.82 ± 1.35 | 11.26 ± 1.41 | <.001a |
| Blood transfusion, n (%) | 0 (0) | 11 (36.7) | <.001b |
Abbreviations: D, add-on dexmedetomidine; C, Control; SD, standard deviation.
Differences between groups analysed by the independent t-test.
Differences between groups analysed by the chi-square test.
Significant difference (P<.05) indicated in bold.
Figure 2.
Comparison of the primary and secondary outcomes between the Dexmedetomidine group (D group) and Control group (C group): (A) Estimated blood loss, (B) Haemoglobin, (C) Mean arterial pressure, and (D) Heart rate. **, *** indicate a significant difference at P < .01, P < .001, respectively. Abbreviations: C, control; D, add-on Dexmedetomidine; ns: no significant difference (P > .05).
The results of the secondary outcomes regarding physiologic measures and medication are shown in Table 3. The MAP at the incision time for Le Fort I and BSSRO (P < .001) (Figure 2C), and HR at the incision time for Le Fort I (P = .004) and BSSRO (P < .001) (Figure 2D) were significantly lower in the D group. No significant differences were observed in ephedrine dosage (P = 1.000) between the 2 groups. The results of the secondary outcomes regarding subject and operative outcomes are shown in Table 4. The overall pain score, intraoperative opioid dosage, postoperative morphine consumption in the recovery room and hospital stay length were significantly lower compared with the C group (P < .001, <.001, .001, and .024, respectively). However, no significant differences were observed in postoperative morphine consumption in the first 24 hours (P = .300) between the 2 groups. The anaesthetic time was significantly shorter in the D group (P = .002). Comparison of the surgical field quality using Fromme's scale and surgeon satisfaction using the Likert scale revealed a significant difference between the 2 groups (P < .001). The surgeons reported a better surgical field quality and higher satisfaction in in the D group compared with C group. As shown in Table 5, the incidence of nausea or vomiting was significantly lower in the D group compared with the C group (P = .045). No significant difference was observed in the incidence of hypotension between the 2 groups (P = 1.000). Additionally, no cases of bradycardia or arrhythmia were reported.
Table 3.
Bivariate analyses of the treatment group versus physiologic measures and medication
| Variable | D group | C group | P-value |
|---|---|---|---|
| (n = 30) | (n = 30) | ||
| MAP (mm Hg), mean ± SD | |||
| at Le Fort I incision | 63.37 ± 5.50 | 72.63 ± 7.46 | <.001a |
| at BSSRO incision | 64.57 ± 5.08 | 71.30 ± 6.38 | <.001a |
| HR (bpm), mean ± SD | |||
| at Le Fort I incision | 67.23 ± 7.82 | 73.60 ± 8.48 | .004a |
| at BSSRO incision | 67.80 ± 8.19 | 76.57 ± 7.28 | <.001a |
| Ephedrine (mg), mean ± SD | 1.20 ± 3.31 | 1.20 ± 4.57 | 1.000a |
Abbreviations: BSSRO, bilateral sagittal split ramus osteotomy; C, Control; D, add-on dexmedetomidine; HR, heart rate; MAP, mean arterial pressure; SD, standard deviation.
Differences between groups analysed by the independent t-test.
Significant difference (P < .05) indicated in bold.
Table 4.
Bivariate analyses of the treatment group versus subject and operative outcomes
| Variable | D group | C group | P-value |
|---|---|---|---|
| (n = 30) | (n = 30) | ||
| Overall pain score (0-10), mean ± SD | 2.43 ± 1.36 | 4.10 ± 1.19 | <.001b |
| Intraoperative opioid (MME), mean ± SD | 16.52 ± 3.91 | 23.58 ± 7.11 | <.001a |
| Postoperative morphine in recovery room (mg), mean ± SD | 0 | 1.10 ± 1.54 | .001a |
| Postoperative morphine in first 24 h (mg), mean ± SD | 2.70 ± 2.45 | 3.37 ± 2.48 | .300a |
| Hospital stay length (days), mean ± SD | 4.77 ± 0.57 | 5.10 ± 0.55 | .024a |
| Anaesthetic time (min), mean ± SD | 282.20 ± 54.74 | 336.90 ± 73.52 | .002a |
| Quality of surgical field (Fromme's scale), mean ± SD | 0.93 ± 0.83 | 2.53 ± 0.94 | <.001b |
| Surgeon satisfaction (5-point Likert scale), mean ± SD | 4.67 ± 0.48 | 3.50 ± 0.86 | <.001b |
Abbreviations: C, control; D, add-on dexmedetomidine; MME, morphine milligram equivalents; SD, standard deviation.
Differences between groups analysed by the independent t-test.
Differences between groups analysed by the Mann-Whitney U test.
Significant difference (P < .05) indicated in bold.
Table 5.
Bivariate analyses of the treatment group versus side effects
| Variable | Total | D group | C Group | P-value |
|---|---|---|---|---|
| (n = 60) | (n = 30) | (n = 30) | ||
| Bradycardia (Heart rate < 50 bpm), n (%) | 0 (0) | 0 (0) | 0 (0) | 1.000a |
| Hypotension (MAP < 55 mm Hg), n (%) | 7 (11.7) | 4 (13.3) | 3 (10.0) | 1.000b |
| Arrhythmia, n (%) | 0 (0) | 0 (0) | 0 (0) | 1.000a |
| Nausea/vomit, n (%) | 17 (28.3) | 5 (16.7) | 12 (40.0) | .045a |
Abbreviations: C, Control; D, add-on dexmedetomidine.
Differences between groups analysed by the chi-square test.
Differences between groups analysed by the Fisher's exact test.
Significant difference (P < 0.05) indicated in bold.
Discussion
The present study's results demonstrated a significant decrease in estimated blood loss, higher postoperative haemoglobin levels, and no incidence of blood transfusion in the D group. The reason may have been due to DEX helping support more stable haemodynamics. DEX does not stimulate the sympathetic autonomic nervous system during hypotensive anaesthesia.28 Therefore, the use of intraoperative antihypertensive drugs was lower. The intraoperative labetalol dosage was also significantly decreased in the D group in the present study. Similar to a previous study,23 DEX better controlled MAP and HR and decreased the dosage of the intraoperative antihypertensive drug. In contrast with another previous study,16 there was no difference in blood loss between the DEX and clonidine group to induce DHA. However, the participants in the DEX group in this study had a greater proportion of double-jaw surgery than in the clonidine group.
When the intraoperative blood loss is less, the quality of the operative visual field is better, allowing the surgeons to work easier, thus, shortening the operative time. In our centre, the surgeons requested preoperative tranexamic acid to improve the quality of the operative visual field in every orthognathic surgery case. As shown in a randomised controlled trial and meta-analysis, tranexamic acid reduces blood loss in orthognathic surgery.29, 30, 31 Single-dose preoperative tranexamic acid combined with DHA controlled blood loss in Le Fort I surgery.32 Moreover, tranexamic acid used in conjunction with DEX under DHA reduced blood loss and improved the quality of the operative visual field in orthognathic surgery.27 In the present study, this combined strategy was applied to reduce blood loss and promote the quality of the operative visual field. The surgeons reported lower Fromme's scale and higher Likert satisfaction scale values. The operative time was also less in the D group compared with C group. Additionally, a non-pharmacological method can be effectively used for DHA, such as the anti-Trendelenburg position and acute normovolemic hemodilution.15
There was a lower overall pain score and intraoperative opioid dosage, and no administration of postoperative morphine in the recovery room in the D group compared with 1.10 ± 1.54 mg in the C group. However, 12/30 patients in the C group needed morphine in the recovery room (range 2-6 mg). This may have been due to the opioid-sparing effect of DEX. Similar to previous studies, DEX decreased the intraoperative opioid requirement,19,23 and reduced postoperative pain after double-jaw surgery.33 DEX provided better pain control during the recovery room period and at the time of discharge, and less opioid usage in children undergoing alveolar bone graft surgery.34 Furthermore, DEX does not have a risk of respiratory depression,34,35 therefore, it is beneficial for the postoperative period. However, postoperative morphine in the first 24 hours was not significantly different between the D and C groups. Because the elimination half-life of DEX is ∼2 to 2.5 hours,21 its effect wore off, thus morphine was needed for pain control during the first 24 hours.
The most common side effects of DEX are hypotension and bradycardia.21,36 These transient effects have been manageable with atropine, ephedrine, fluid infusion, or discontinuing the DEX without any treatments. Nevertheless, caution should be considered, particularly in patients with impaired left ventricular function, hypovolemia, vasoconstriction, or severe heart block, where the sympatholytic actions of alpha-2 adrenergic agonists may exacerbate underlying conditions.21,37 Additionally, continuous electrocardiography monitoring is mandatory, with prompt response and treatment required for any adverse events. The occurrence of hypotension, bradycardia, and conduction block associated with DEX administration is closely related to the loading dose and infusion rate.38 By administering the slow bolus and titrating the infusion rate gradually, these adverse effects can be mitigated. Consequently, it is crucial to carefully choose appropriate patients and dosing regimens to ensure the safe utilisation of DEX. The dosage regimen for DEX is calculated based on patient weight. The recommended dosage is a loading dose of 1 mcg/kg over 10 minutes, followed by a maintenance infusion of 0.2 to 1.0 mcg/kg/h.39 The maximum dosage of DEX for maintenance infusion is 1.4 mcg/kg/h.37 Overdose of DEX may result in first- or second-degree atrioventricular block.21 Consistent with the previous studies on DEX use in orthognathic surgery,16,23 a dosage regimen of 0.5 to 1 mcg/kg bolus followed by an infusion of 0.2 to 0.5 mcg/kg/hour infusion was employed. To enhance DEX's effectiveness while mitigated potential adverse effects, a dosage regimen of 1 mcg/kg DEX bolus over 10 minutes, followed by a maintenance infusion of 0.4 mcg/kg/hour, was implemented in the present study. In this study, there was no meaningful bradycardia and arrhythmia in either group. Furthermore, the intraoperative hypotension and the usage of sympathomimetic drugs, such as ephedrine, were not different between the 2 groups. Therefore, DEX is safe and rarely has side effects when administered as in this study.
The most common side effect in this study was nausea/vomiting, especially in the C group. The cause of nausea/vomiting might be from the opioids’ side effects. The lower total dosage of opioid in the D group decreased the risk of nausea/vomiting. A previous study reported a significantly lower incidence of nausea in the DEX group (3.3%) compared with the placebo group (46.7%).33
There was a shorter hospital stay length in the D group. The risk factors for increasing the length of hospital stays were blood loss, blood transfusion, operative time, and the extensiveness of the surgical procedure.6 Because the baseline characteristics and the type of surgical procedure were similar in this study, the difference in the hospital stay length might be due to the difference in blood loss, the incidence of blood transfusion, and the anaesthetic time.
In the present study, the mean blood loss was relatively higher than in previous studies. The mean blood loss in orthognathic surgery in Thailand tends to be higher than in the meta-analysis. In a retrospective study in Thailand, the mean blood loss was 854.8 ± 442.8 mL (range 200-3400 mL) in double-jaw surgery using DHA.40 A randomised clinical trial in Thailand found that the mean blood loss was 785.00 ± 391.05 mL in double-jaw surgery using DHA with DEX.19 However, even if the estimated blood loss is lower in studies outside of Thailand, the 55% reduction in bleeding when adding-on DEX was clinically significant. Additionally, the dosage of DEX can be increased up to 0.7 mcg/kg/h to control the intraoperative haemodynamics. However, further studies should be considered to determine whether the cardiovascular side effects will be greater when administering a higher dosage of DEX.
In the present study, the anaesthetic time was quite long. This might depend on the surgical technique. Moreover, although this study was performed at a training centre for oral and maxillofacial surgery residents; every case was done under the supervision of well-experienced maxillofacial surgeons. The mean hospital stay was relatively longer than other previous studies because the postoperative hospital stay after bimaxillary orthognathic surgery in Thailand is relatively longer, generally 3 to 4 days, for postoperative intravenous antibiotic administration and postoperative observation.
Given the relatively small sample size of this study, further investigation, particularly in larger cohorts, is required to confirm the results and assess the potential for rare adverse effects. In conclusion, adding-on dexmedetomidine in orthognathic surgery significantly reduced estimated blood loss by over 50% and improved patient outcomes, especially in terms of overall pain score, quality of the surgical field, and incidence of nausea/vomiting. Therefore, DEX can be considered a safe and effective medication for performing DHA.
Conflict of interest
None disclosed.
Acknowledgments
Author contributions
Thunshuda Sumphaongern: Conception and design of study, Acquisition of data: laboratory or clinical, analysis of data. drafting of article and/or critical revision, final approval of manuscript. Soranun Chantarangsu: Conception and design of study, analysis of data, drafting of article and/or critical revision, final approval of manuscript.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not- for-profit sectors.
Acknowledgements
The authors thank Dr. Kevin Tompkins for revising the language in the manuscript.
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