|Year : 2022 | Volume
| Issue : 1 | Page : 1-7
Efficacy of combined thoracic paravertebral block and intravenous dexmedetomidine in medical thoracoscopy: a randomized controlled trial
Ayman M Maaly1, Ahmed M Abdelhady2, Rehab A Abdelaziz1
1 Department of Anaesthesia and Surgical Intensive Care, Faculty of Medicine, Alexandria University, Alexandria, Egypt
2 Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt
|Date of Submission||16-Sep-2020|
|Date of Decision||23-Sep-2020|
|Date of Acceptance||29-Jan-2021|
|Date of Web Publication||13-May-2022|
MD Rehab A Abdelaziz
Department of Anaesthesia and Surgical Intensive Care, Faculty of Medicine, Alexandria, 21131
Source of Support: None, Conflict of Interest: None
Background Medical thoracoscopy has become the gold standard for evaluation of intrapleural space. Thoracic paravertebral block is instillation of local anesthetic drug in the thoracic paravertebral space and can be used in several procedures such as medical thoracoscopy. Dexmedetomidine is a potent α-2 agonist with a higher potency and short duration of action. It has a rapid onset and offset. It produces an ‘interactive’ form of sedation and does not induce respiratory depression. This study was conducted to evaluate the efficacy of paravertebral block with intravenous (i.v.) infusion of dexmedetomidine compared with standardized general anesthesia method in medical thoracoscopy.
Patients and methods A randomized controlled trial was conducted in the Department of Chest Diseases at Alexandria Main University Hospital, on patients indicated for medical thoracoscopy.
Patients were randomized into two groups (30 patients each). Group A received general anesthesia. Group B received paravertebral block at the level of medical thoracotomy covering three levels: at, above, and below thoracotomy level plus i.v. dexmedetomidine. Demographic data, hemodynamics, patient-rated procedural pain, and operator-rated overall procedure satisfaction scores were recorded.
Results A significantly lower means of heart rate and blood pressure were found in group B after thoracotomy and immediately postoperative. Patient-rated procedural pain score in group A ranged from 2 to 5 with a mean of 3.90±0.85, while in group B, it ranged from 0 to 3 with a mean of 1.40±0.68. This difference was statistically significant (P<0.001). A significantly higher operator-rated overall procedure satisfaction score was found in group B (95.77±1.74) compared with group A (90.03±2.33) (P<0.001).
Conclusion Use of thoracic paravertebral block plus use of i.v. dexmedetomidine in medical thoracoscopy is comparable to general anesthesia as it is comfortable to the patient and the operator without dealing with airway and its difficulties.
Keywords: IV dexmedetomidine, medical thoracoscopy, thoracic paravertebral block
|How to cite this article:|
Maaly AM, Abdelhady AM, Abdelaziz RA. Efficacy of combined thoracic paravertebral block and intravenous dexmedetomidine in medical thoracoscopy: a randomized controlled trial. Res Opin Anesth Intensive Care 2022;9:1-7
|How to cite this URL:|
Maaly AM, Abdelhady AM, Abdelaziz RA. Efficacy of combined thoracic paravertebral block and intravenous dexmedetomidine in medical thoracoscopy: a randomized controlled trial. Res Opin Anesth Intensive Care [serial online] 2022 [cited 2022 Oct 6];9:1-7. Available from: http://www.roaic.eg.net/text.asp?2022/9/1/1/345224
A.M.M. this author helped conception, design, and conduction of the study, analyzed the data, and wrote the paper. A.M.A.: this author helped review and edit the paper. R.A.A.: this author helped review and edit the paper.
| Background|| |
Medical thoracoscopy, as a simple, safe, and minimally invasive procedure, has become the gold standard for evaluation of intrapleural space for diagnosis and treatment of a lot of thoracic disorders such as pleural effusion, especially exudative type, pleural tumors, and others ,.
Local anesthesia (LA) was commonly used in medical thoracoscopy to replace the more complex general anesthesia with a lower cost. The use of LA in medical thoracoscopy, especially needing frequent administration of sedatives, has gained less popularity because it is less comfortable to the patient and to the operator. So, we need an alternative appropriate method for medical thoracoscopy using nonintubating technique ,,.
Thoracic paravertebral block (TPVB) is instillation of LA drug in the thoracic paravertebral space and can be used in several procedures such as medical thoracoscopy, video-assisted thoracoscopic surgery, lobectomy, pneumonectomy, etc. Also, insertion of a catheter in the paravertebral space for continuous intraoperative and postoperative analgesia can be done .
Dexmedetomidine is a potent α-2 agonist with a higher potency and short duration of action. The relatively short-distribution half-life of ∼6 min of dexmedetomidine results in rapid onset of sedation, and an elimination half-life of ∼2 h facilitates clearance of the drug. It produces an ‘interactive’ form of sedation, in which patients may be aroused easily with stimulation, and are cooperative once aroused. Moreover, it has analgesic properties, does not induce respiratory depression at clinically relevant doses, and has predictable sympatholytic effects ,.
Hence, this study was conducted to evaluate the efficacy of TPVB with intravenous (i.v.) infusion of dexmedetomidine (degree of analgesia) compared with standardized general anesthesia method in medical thoracoscopy. The primary outcome was to compare the patient-rated pain scores in two groups of patients receiving each of the interventions. The secondary outcomes were assessment of operator-rated satisfaction score and hemodynamic changes in both groups.
| Patients and methods|| |
This randomized controlled trial was approved by the Institutional Review Board at Alexandria Faculty of Medicine (IRB No: 00012098). A written informed consent was obtained from all subjects participating in the trial and confidentiality of data was ensured. The study was registered prior to patient enrollment at Pan African Clinical trial Registry database (ID: PACTR202005777730971, principal investigator: Ayman M. Maaly, Date of registration: 30/4/2020). This paper adheres to the applicable CONSORT guidelines.
The study was conducted in the Department of Chest Diseases at Alexandria Main University Hospital, on patients indicated for medical thoracoscopy (mainly patients with undiagnosed exudative pleural effusion) American Society of Anesthesiologists II and III, aged 25–55 years with no history of allergy to any of the used drugs.
The sample size was calculated using G*Power 3.1 program (Heinrich-Heine University, Düsseldorf, Germany) based on the expected difference in the postoperative analgesia between cases and control groups (total morphine consumption 17.4±8.7 vs. 2.4±2.8 mg), at 5% level of significance and a power of 80% with a ratio of 1 : 1 .
Preoperative evaluation included detailed medical and surgical history, complete clinical examination, routine laboratory investigations, chest x-ray, ECG, and computed tomography chest if needed. Patients with a known allergy to the used drugs, vertebral column deformities, coagulopathies, injection-site infection, liver or renal impairment, severe respiratory distress, addicts, patients receiving antihypertensive drugs, and those with psychiatric disorders were excluded from the study.
Preoperatively, patients were taught how to evaluate their pain grade using the visual analog scale (VAS), scored from 0 to 10 (where 0=no pain and 10=the worst pain imaginable). Oral diazepam (5 mg) was taken at night before the procedure. At the operating room, a 18-gauge cannula was inserted. Lactated Ringer’s solution 10 ml/kg was infused i.v. over 15 min before the initiation of anesthesia. About 1 g of ceftriaxone was injected i.v. after doing hypersensitivity test. Basic monitoring (electrocardiography, noninvasive blood pressure, O2 saturation, and temperature) was applied.
The CONSORT flow diagram of the study is presented in [Figure 1]. Patients were allocated into two groups of 30 patients each using a computer-generated random-number assignment in sealed opaque envelopes. A staff anesthesiologist not involved in the study or management of the patient prepared the injectate according to randomization.
Group A patients, the general anesthesia group, received i.v. propofol 2 mg/kg, fentanyl 2 μg/kg, cisatracurium 0.1 mg/kg, and xylocaine 1.5 mg/kg. Maintenance with isoflurane MAC 1.2–1.4% with endotracheal tube insertion. Target EtCO2 was 30–35 mmgh. Then, the patient was turned to the lateral recumbent position.
Group B, after explaining the procedure to the patient, received paravertebral block (PVB) at the level of medical thoracotomy covering three levels: at, above, and below thoracotomy level, using a mixture of xylocaine 0.1% and marcaine 0.25% (total volume 6 ml, 3 ml of each) for 30 min, using a needle with remarks for distance, before the procedure. The success of the block was tested by decreased pin-prick sensation at the expected dermatomal level. After 20 min, a loading dose of i.v. dexmedetomidine of 1 μg/kg over 10 min was given. The patient was turned to the lateral recumbent position and then maintained with 0.3 μg/kg all over the procedure till reaching grade 3–4 sedation level on modified Ramsay scale in a nonintubated patient with nasal cannula oxygen flow 2 l/min.
The block was done in the sitting position with midazolam i.v. 2–3 mg. Intradermal lidocaine was used at the site of the needle insertion. The superior aspect of the spinous processes of T1–T6 was marked. The skin entry points were 3 cm lateral to the mark of the desired level of thoracotomy. A 22-gauge quincke spinal needle attached through extension tubing to a syringe containing the study drugs was used. The needle was inserted perpendicular to the skin till hitting the transverse process of the desired level. The needle was withdrawn and walked cephald off the transverse process and advanced for a further 1.5–2 cm with loss of resistance technique.
Postoperative analgesia (0.01 mg/kg morphine i.v.) was provided if needed.
- Demographic data: age, sex, and weight.
- Hemodynamics: heart rate (beats/min), mean arterial blood pressure (mmHg), and SpO2% (preoperative, during the procedure after thoracotomy, and immediate postoperative).
- Sedation score: the dose of dexmedetomidine was titrated till the sedative effect (grade 3–4 modified Ramsay scale) during the procedure while watching the heart rate and mean arterial blood pressure (MABP).
- Patient-rated procedural pain on VAS immediately postoperative after recovery.
- Operator-rated overall procedure satisfaction (quality of the image, ease of maneuvering, ease of obtaining a biopsy sample, and the expectation that the biopsy sample would reveal a definitive histological diagnosis) on VAS from 0 to 100.
The raw data were coded, entered, and analyzed using IBM SPSS Software Package version 21 (IBM SPSS Statistics for Windows, Version 21.0, Released 2012; IBM Corp., Armonk, New York, USA). The 5% level was used as the cutoff value for statistical significance.
The following statistical measures were used: descriptive statistics, including counts and percentages for qualitative variables, and arithmetic mean and SD for quantitative ones. One-sample Kolmogorov–Smirnov test was used for testing the distribution of quantitative variables. As all quantitative variables showed to be normally distributed, parametric tests were used for the analysis. Student’s t-test was used for comparing two independent quantitative normally distributed variables. Paired t-test (before and after) was used for comparing the basal value with each of the other periods. χ
2-test was used to test the association between two categorical variables or to detect the difference between two or more proportions.
| Results|| |
The present study included two groups of 30 patients each. [Table 1] shows the general characteristics of the studied patients. The age of group A patients ranged from 28 to 55 years with a mean of 40.37±7.85 years, whereas in group B, it ranged from 25 to 54 with a mean of 41.63±9.71 years. No statistically significant difference was found between the two groups regarding age, sex, and body weight.
[Table 2] illustrates the hemodynamic changes in the two studied groups. Preoperatively, the heart rate of group A patients ranged from 58 to 84 beats/min with a mean of 74.67±6.75, while in group B patients, it ranged from 60 to 85 with a mean of 72.43±7.74 with no statistically significant difference between the two groups. A statistically significant decrease of the mean heart rate was observed in patients of each group after thoracotomy as well as immediately postoperative. However, a significantly lower mean heart rate was found in group B after thoracotomy (63.57±3.90 beats/min) compared with that of group A (66.03±4.53 beats/min) (P=0.028). Also, the mean heart rate measured immediately postoperative was significantly lower in group B (66.70±4.09 beats/min) compared with that of group A (69.90±5.58 beats/min), P=0.014.
Regarding the MABP, similarly, no statistically significant difference between the two groups was found preoperatively. Then, a statistically significant decrease of the MABP was observed in patients of each group after thoracotomy as well as immediately postoperative. However, a significantly lower MABP was found in group B after thoracotomy and immediately postoperative (74.30±3.27 and 87.73±3.76 mmHg, respectively) compared with group A (82.2±2.91 and 93.1±3.76 mmHg, respectively), P<0.001.
Changes in oxygen saturation (SpO2) are presented in [Table 3]. There were no statistically significant differences in SpO2 between the two groups on all timings of measurement.
Patient-rated procedural pain score was recorded on VAS immediately after recovery and the results of the two studied groups are compared in [Table 4]. In group A, the score ranged from 2 to 5 with a mean of 3.90±0.85, while in group B, it ranged from 0 to 3 with a mean of 1.40±0.68. This difference was statistically significant (P<0.001).
|Table 4 Comparison between patient-rated procedural pain on visual analog scale immediately after recovery in the two studied groups|
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Comparison between operator-rated overall procedure satisfaction score in the two studied groups is demonstrated in [Table 5]. A significantly higher mean satisfaction score was found in group B (95.77±1.74) compared with group A (90.03±2.33), P<0.001.
|Table 5 Comparison between operator-rated overall procedure satisfaction in the two studied groups|
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| Discussion|| |
PVB is a good choice for analgesia intraoperatively and postoperatively in thoracic procedures. Dexmedetomidine is a new potent α1 agonist with potent analgesic effects. In the current study, we compared standard general anesthesia with thoracic PVB with i.v. dexmedetomidine for thoracoscopic procedure. Patients of the two groups were comparable in age, sex, and body weight with no statistically significant differences.
Regarding hemodynamic changes, our results revealed that after thoracotomy and in the immediate postoperative period, there was a significant decrease in heart rate and MABP in both groups, but a significantly lower heart rate and MABP were observed in the group that received PVB with i.v. dexmedetomidine.
These findings may be explained by direct myocardial depression and vasodilator effect of dexmedetomidine (α1-agonist effect). However, we can titrate the dose of dexmedetomidine till the sedative effect (grade 3–4 modified Ramsay scale) during the procedure while watching the heart rate and MABP.
In concordance with these results, Mohamed et al.  in 2014 concluded that the use of dexmedetomidine may result in significant bradycardia and hypotension. Similarly, Dutta et al.  in 2017 revealed that its use may be associated with bradycardia and/or hypotension.
Post-thoracotomy pain can alter chest-wall mechanics and impede effective chest expansion and coughing. This predisposes patients to ventilation/perfusion mismatch, atelectasis, hypoxemia, infection, and delayed recovery ,. Effective analgesia is fundamental to decrease these sequlae . In addition, to avoid chronicity of pain, acute pain should be treated adequately ,.
Thoracic epidural analgesia was considered the first choice for treatment of post-thoracotomy pain. However, possible devastating complications can occur, such as spinal hematoma, epidural abscess, and the resulting paraplegia . Then, PVB is considered a good choice or even superior to epidural analgesia to relieve post-thoracotomy pain ,.
In the present study, there was a significantly lower patient-rated procedural pain score, with significantly higher operator-rated overall procedure-satisfaction score, in the group that received PVB with i.v. dexmedetomidine compared with the general anesthesia group. This could be explained by the analgesic effect of dexmedetomidine as it decreases tumor necrosis factor-α level and suppresses interleukin-6 production. Moreover, PVB inhibits conduction of afferent pain fibers in the target thoracic levels . This may be also due to using a minimally invasive procedure (nasal cannula), avoiding airway, and its difficulties. In addition, the interactive form between the operator and the patient, and biopsy yielding, is good and comparable to the general anesthesia method. Also, the patient is satisfied as no EET insertion was done and thus no postoperative croup, sore throat, etc.
Several studies demonstrated that addition of dexmedetomidine to LA in epidural anesthesia or paravertebral route can decrease surgical stress response, improve quality and duration of postoperative analgesia, and decrease opioid consumption without causing respiratory depression ,,,.
Similarly, previous studies have demonstrated the benefits of PVB for analgesia after thoracoscopic procedures and of dexmedetomidine to increase the duration of nerve blockade ,,,,.
Also, Hill et al.  reported that using a PVB with bupivacaine is effective in reducing pain after thoracoscopic surgery during the first 6 h after administration. It was also reported that single-injection PVB can provide satisfactory analgesia in the early postoperative period compared with continuous wound infiltration with LA .Dutta et al.  suggested that PVB with ropivacaine and dexmedetomidine is the best method for postoperative pain control following thoracoscopic lobectomy. Another study found that dexmedetomidine, as an adjuvant to bupivacaine in TPVB, significantly decreased pain scores at rest and on movement after breast cancer surgery .
On the other hand, in a study evaluating PVB after mastectomy surgery, it was shown that one-time PVB with ropivacaine (0.5%) alone did not have an analgesic benefit as compared with saline after discharge from the postanesthesia care unit . Another study, also after mastectomy surgery, found that single-injection PVB provided more adequate analgesia during the early postoperative period, but had negligible effects later on, as compared with continuous wound infiltration with LA .
This study had some limitations. For instance, information on general ambulation, resumption of activities of daily living, food and drink and time to discharge, and related postoperative indicators were not recorded in the study. Further study is recommended using dexmedetomidine in a mixture with LA in TPVB.
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Conflicts of interest
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]