Anesthesiology and Pain Medicine
Volume:11 Issue: 2, Apr 2021

Context:

 Radiofrequency therapy is a medical procedure mainly used to reduce pain with a low complication rate (less than 1%), ease of application, and low cost. This review’s objective was to (1) evaluate the pulsed radiofrequency (PRF) effectiveness in treating radicular pain and (2) assess the PRF procedure’s safety in managing radicular pain in lumbar herniated nucleus pulposus (HNP).

 A systematic review and meta-analysis. A tertiary care center and an academic medical center. Six full articles with the following features were selected for this review: (1) Articles published in English; (2) studies on the PRF effect on radicular pain in lumbar HNP; and (3) randomized control trials.

 The studies showed that the PRF group had a reduction in pain scores at each evaluation. In four of the studies, the PRF group showed a more significant reduction in pain scores than the control, and in two of the studies, the reduction in pain scores was not significant in the PRF group compared to the control. An adverse effect was reported in one patient experiencing increased radicular pain after PRF. Lack of data required for statistical analysis, and lack use of a uniform duration for the PRF procedure by all the studies.

 PRF can be used as a promising clinical recommendation for pain management with minimally invasive radicular pain techniques due to lumbar HNP.
 

Context: 

Abdominal pain is a widespread complaint and is one of the common reasons leading patients to seek medical care, either in emergency situations or with their primary providers. While acute abdominal pain is a better defined, usually surgical condition, chronic abdominal pain requires longer, typically lifelong, therapy. Chronic abdominal pain may also present with acute flares and complications. Here we review seminal and novel evidence discussing the use of acupuncture in the treatment of abdominal pain, indications, and conditions that may benefit from this approach.

Evidence Acquisition:

 Chronic abdominal pain is a common complaint causing significant morbidity and disability and has a hefty price tag attached. Recent studies show it may be prevalent in as much as 25% of the adult population. It is defined as three episodes of severe abdominal pain over the course of three months. Chronic abdominal pain could be the result of chronicity of acute pain or of chronic pain syndromes, most commonly IBD syndromes and IBS. While a plethora of treatments exists for both conditions, these treatments usually fall short of complete symptom control, and there is a need for complementary measures to curb disability and increase the quality of life in these patients. Acupuncture is a form of integrative medicine that has long been used in Chinese and traditional medicine, based on the rebalancing of the patient’s Qi, or Ying/Yang balance. It has been shown to be effective in treating several other conditions, and novel evidence may expand its use into other fields as well. Clinical trials studying acupuncture in chronic pain conditions have been promising, and recent evidence supports the use of abdominal pain in chronic abdominal pain conditions as well. Though not curative, acupuncture is a complementary approach that helps reduce symptoms and improved quality of life.

 Chronic abdominal pain is a widespread condition, mostly affected by the IBS and IBD spectrum. Etiologies are still being studied for these conditions, and while novel treatment approaches are absolute game changers for these patients, many continue to experience some level of symptoms and disability. Acupuncture may provide further alleviation of these symptoms in select patients, thus improving quality of life, reducing disability, and saving healthcare dollars. It is a largely safe and inexpensive method that may significantly contribute to the quality of life of selected patients.

Context:

 Chronic neuropathic pain is a common condition, and up to 11.9% of the population have been reported to suffer from uncontrolled neuropathic pain. Chronic pain leads to significant morbidity, lowered quality of life, and loss of workdays, and thus carries a significant price tag in healthcare costs and lost productivity. dorsal root ganglia (DRG) stimulation has been recently increasingly reported and shows promising results in the alleviation of chronic pain. This paper reviews the background of DRG stimulation, anatomical, and clinical consideration and reviews the clinical evidence to support its use.

Evidence Acquisition: 

The DRG span the length of the spinal cord and house the neurons responsible for sensation from the periphery. They may become irritated by direct compression or local inflammation. Glial cells in the DRG respond to nerve injury, producing inflammatory markers and contribute to the development of chronic pain, even after the resolution of the original insult. While the underlying mechanism is still being explored, recent studies explored the efficacy of DRG stimulation and neuromodulation for chronic pain treatment.

 Several reported cases and a small number of randomized trials were published in recent years, describing different methods of DRG stimulation and neuromodulation with promising results. Though evidence quality is mostly low, these results provide evidence to support the utilization of this technique.

 Chronic neuropathic pain is a common condition and carries significant morbidity and impact on the quality of life. Recent evidence supports the use of DRG neuromodulation as an effective technique to control chronic pain. Though studies are still emerging, the evidence appears to support this technique. Further studies, including large randomized trials evaluating DRG modulation versus other interventional and non-interventional techniques, are needed to further elucidate the efficacy of this method. These studies are also likely to inform the patient selection and the course of treatment.

Schizophrenia is ranked among the top 10 global burdens of disease. About 1% of people meet the diagnostic criteria for this disorder over their lifetime. Schizophrenic patients can develop cataract, particularly related to age and medications, requiring surgery and anesthesia. Many concerning factors, including cognitive function, anxiety, behavioral issues, poor cooperation and paroxysmal movements, may lead to general anesthesia as the default method. Antipsychotic agents should be continued during the perioperative period if possible. Topical/regional anesthesia is suitable in most schizophrenic patients undergoing cataract surgery. It reduces potential drug interactions and many postoperative complications; however, appropriate patient selection is paramount to its success. General anesthesia remains the primary technique for patients who are considered unsuitable for the topical/regional technique. Early involvement of a psychiatrist in the perioperative period, especially for patients requiring general anesthesia, is beneficial but often under-utilized. This narrative review summarizes the anesthetic considerations for cataract surgery in patients with schizophrenia.

Context: 

Neck pain is a common phenomenon and affects a large segment of the population. Chronic neck pain, lasting more than 3 months, likely occurs in 10% - 30% of patients with acute neck pain and affects up to 288 million cases globally, carrying a significant cost in terms of quality of life, disability, and healthcare dollars. Here we review neck pain background, acupuncture and the evidence that exist to support acupuncture use in chronic neck pain.

 Neck pain not only affects quality of life directly, but also contributes to depression, job dissatisfaction and reduced productivity. Unfortunately, neck pain is strongly linked to office and computer work and is likely to continue increasing in prevalence. Traditional treatments, such as analgesics, physical therapy, exercise, and non-invasive therapy bring some relief, and invasive therapy is indicated if anatomical pathologies exist. Acupuncture is a form of integrative medicine, originally described and practiced in traditional Chinese medicine and now expanded to include methods including acupressure, dry needling, and others. Traditionally, it focused on restoring the patient’s flow of Qi by puncturing specific points along the meridians. It has previously been shown to be effective in other forms of chronic pain and disability. Clinical trials studying acupuncture for neck pain have shown significant reduction in both pain and associated symptoms. These therapies are reviewed in this text.

 Neck pain is a common and significant global problem. Acupuncture, dry needling, and cupping were all shown to be effective in alleviating pain both immediately after treatment, as well as provide long-lasting relief. These treatments are generally safe and inexpensive and should be considered as part of a multimodal approach for the treatment of neck pain. More head-to-head studies will provide better data to support a choice of a specific treatment over another.

Since December 2019, the outbreak of coronavirus disease 2019 (COVID-19) has spread worldwide. Although the majority of patients show mild symptoms, the disease can rapidly progress in severe cases and develop acute respiratory distress syndrome (ARDS) that may lead to therapeutic interventions, including oxygenation, tracheal intubation, and mechanical ventilation. It is suggested that the new coronavirus spreads mostly via droplets, surface contact, and natural aerosols. Hence, high-risk aerosol-producing procedures, such as endotracheal intubation, may put the healthcare workers at a high risk of infection. In the course of managing patients with COVID-19, it is essential to prioritize the safety of healthcare workers. Hence, this review study aimed to summarize new guidelines and proper airway management in adult and pediatric COVID-19 patients.

 This study aimed to compare the analgesic effect of single-dose spinal versus epidural analgesia for labor pain to verify if applying a single dose spinal analgesia is an efficient technique for labor pain management as an alternative for epidural analgesia.

 A total of 128 women in the active phase of labor were randomly allocated into two groups of spinal analgesia (n = 64) and epidural analgesia (n = 64). The latter received a bolus dose of 16 mL of 0.125% bupivacaine and 50 μg fentanyl and repeated 5 - 10 mL of bolus dose. The former received 2.5 mg hyperbaric bupivacaine plus 50μg fentanyl. Pain intensity was measured using the visual analog scale (VAS). The duration of analgesia, mode of delivery, the duration of labor, side effects, and maternal satisfaction were also compared.

 There were no significant differences in the rate of cesarean section, duration of labor, postpartum hemorrhage, and the frequency of the fetal heart deceleration until 30 min after analgesia between the two groups. Measured pain after 30 (P = 0.0001) and 90 min (P = 0.01) was significantly lower in the spinal group than the epidural group. However, there was no significant difference between the spinal and epidural groups concerning the VAS scores at 150, 210, and 270 minutes. Maternal satisfaction was higher in the spinal group (P = 0.002). The mean duration of analgesia was longer in the spinal group than the epidural group (P = 0.0001).

 According to the findings, single-dose spinal analgesia, compared to epidural analgesia, is a safe, fast, and efficient technique for labor analgesia, which can be easily performed. In addition, it provides a high satisfaction level in the parturient.

 Breast cancer (BC) is the most frequent cause of cancer death in women. The thoracic pectoral nerve (PECS) block has been described as the gold standard analgesic modality for BC surgery. It has been previously reported that PECS is associated with decreased BC recurrence post-mastectomy. Although several anesthetic drugs and techniques are used in surgical oncology, their effects on the behavior of cancer cells are yet to be known and the key question of whether the anesthetic technique affects cancer outcome remains unresolved.

 Since anesthetic drugs and techniques and post-operative pain may affect BC recurrence, this study aimed to determine whether the anesthetic choice and technique, PECS II block, affects in vitro apoptosis of the MDA-MB-231 BC cell line.

 Twenty-two female BC patients, 20 to 75-years-old, with the same pathologic grades were included in this study. The patients were randomly divided into two groups. The first group received propofol general anesthesia (PGA) associated with PECS and the second group received standard PGA. Blood was sampled pre and post-operation from all patients. The sera were isolated and then exposed to the MDA-MB-231 human BC cell line. The mean percentage of apoptosis indices was analyzed by flow cytometry using Annexin V-fluorescein isothiocyanate 24 hours after treatment with patients’ sera.

 A significant decrease was seen in the mean viability percentage of BC cell line in the PECS group, besides a significant increase in the mean percentage of necrosis and late apoptosis indices compared to the control group after exposure to sera collected from patients post-operation. Intra-group analysis of the control group showed that the exposure of the tumoral cell to post-operation sera resulted in a significant increase in the mean percentage of necrosis and late apoptosis index compared to pre-operation sera exposure. In the PECS group, the exposure of the tumoral cell to post-operation sera resulted in a significant increase in the mean percentage of cell viability and late apoptosis index compared to pre-operation sera exposure.

 In conclusion, anesthesia and BC surgery may induce apoptosis indices in the MDA-MB-231 human BC cell line. We also found that sera collected from PECS II block patients with BC could induce more apoptosis in the MDA-MB-231 cell line compared to collected sera from systemic analgesia alone after BC surgery.

 COVID-19 has become a pandemic since December 2019, causing millions of deaths worldwide. It has a wide spectrum of severity, ranging from mild infection to severe illness requiring mechanical ventilation. In the middle of a pandemic, when medical resources (including mechanical ventilators) are scarce, there should be a scoring system to provide the clinicians with the information needed for clinical decision-making and resource allocation.

 This study aimed to develop a scoring system based on the data obtained on admission, to predict the need for mechanical ventilation in COVID-19 patients.

 This study included COVID-19 patients admitted to Sina Hospital, Tehran University of Medical Sciences from February 20 to May 29, 2020. Patients' data on admission were retrospectively recruited from Sina Hospital COVID-19 Registry (SHCo-19R). Multivariable logistic regression and receiver operating characteristic (ROC) curve analysis were performed to identify the predictive factors for mechanical ventilation.

 A total of 681 patients were included in the study; 74 patients (10.9%) needed mechanical ventilation during hospitalization, while 607 (89.1%) did not. Multivariate logistic analysis revealed that age (OR,1.049; 95% CI:1.008-1.091), history of diabetes mellitus (OR,3.216; 95% CI:1.134-9.120), respiratory rate (OR,1.051; 95% CI:1.005-1.100), oxygen saturation (OR,0.928; 95% CI:0.872-0.989), CRP (OR,1.013; 95% CI:1.001-1.024) and bicarbonate level (OR,0.886; 95% CI:0.790-0.995) were risk factors for mechanical ventilation during hospitalization.

 A risk score has been developed based on the available data within the first hours of hospital admission to predict the need for mechanical ventilation. This risk score should be further validated to determine its applicability in other populations.

 Maintaining hemodynamic stability during intracranial surgery is one of the most important tasks. There is no general agreement regarding which anesthetics are optimal for craniotomy. Propofol and short-acting opioids are usually used, but their use is not without side effects. Recently, dexmedetomidine has been considered a safe alternative in different surgeries.

 We aimed to assess the efficacy of 0.5 µg/kg/h dexmedetomidine infusion without loading dose as an adjunct to general anesthesia for craniotomy.

 A prospective, randomized, double-blinded, parallel-group, placebo-controlled trial was conducted. Setting: Single university teaching hospital’s operating rooms and postoperative intensive care unit. Patients: A total of 50 patients scheduled for elective supratentorial craniotomy participated in this study. Interventions: Patients were randomly divided into either control group (group C) and Dexmedetomidine group (group D). Main outcome measure: Intraoperative hemodynamics measurements at specific timings.

 We found that dexmedetomidine had significantly maintained mean arterial blood pressure and heart rate (P-value < 0.001); with lower intraoperative fentanyl and propofol consumption in group D (132 ± 35 µg and 14 ± 30 mg, respectively) when compared to group C (260 ± 38 µg and 534 ± 66 mg, respectively). Finally, a lesser sedation level was noticed in the dexmedetomidine group, together with a significantly lesser recovery time of 10.3 ± 4 min.

 Dexmedetomidine infusion without loading dose could be an efficacious and safe agent in achieving hemodynamic stability with intraoperative opioid-sparing effect and lesser recovery time.

 Caudal anesthesia is an effective method of pain management, which can be successfully employed to minimize post-thoracotomy pain in pediatric patients. However, its main disadvantage is the short postoperative analgesic period, which can be prolonged by the concurrent administration of one of many adjuvants.

 This prospective randomized, blinded study aimed to compare the efficacy of dexmedetomidine versus morphine as adjuvants to bupivacaine in caudal anesthesia for thoracic surgeries in pediatric patients.

 Fifty patients were randomly allocated into two equal groups. To achieve caudal epidural block anesthesia, the patients in group M (n = 25) were administered morphine and bupivacaine, while group D (n = 25) received a mixture of dexmedetomidine and bupivacaine. The primary outcome of this study was the postoperative analgesic duration achieved. The secondary outcomes included morphine administration in the first 24 hours following caudal block anesthesia, the face, legs, activity, cry, consolability (FLACC) scale scores, and adverse effects, including vomiting, itching, bradycardia, hypotension, and respiratory depression.

 The results showed that patients who had received dexmedetomidine achieved a longer postoperative analgesia as compared to those who had received morphine (P < 0.001). Postoperatively, the heart rate, blood pressure, pain score, and mean consumption of morphine were lower in group D as compared to the group M. There was no significant difference in the adverse effects between the two groups.

 The use of dexmedetomidine as an adjuvant to bupivacaine for caudal anesthesia during pediatric thoracic surgeries induced better and prolonged postoperative analgesia as compared to morphine.
 

 Ketofol's effect on hemodynamics and the airway response during inducing general anesthesia has been studied previously. However, ketofol's effect on the smoothness of extubation has not been studied yet.

 We aimed to assess ketofol’s effect on the smoothness of extubation and compare it with propofol for inducing general anesthesia.

 This double-blind, randomized, and controlled study was conducted on 106 class I and II female patients with the “American Society of Anesthesiologists Physical Status (ASAPS),” aged 18 - 40 years, scheduled for laparoscopic drilling for polycystic ovary disease under general anesthesia. The patients were assigned to two groups of 53 patients each: Group KP = ketofol and Group P = propofol.

 There was an excellent sedation score during suction and extubation in the ketofol group. The airway response and smoothness of extubation were better in the ketofol group than in the propofol group.

 Ketofol as an induction anesthetic agent more effectively attenuated the airway response during extubation than only propofol.
 

 Post-arthroscopic shoulder surgery pain is severe enough to interfere with initial recovery and rehabilitation.

 We aimed to evaluate the analgesic effects of postoperative ultrasound-guided suprascapular plus axillary nerve blocks superficial subepidermal axon bundles (SSAB) with interscalene block (ISB) in arthroscopic shoulder surgery.

 In this single-blind randomized, open-label clinical trial, 80 candidates of elective arthroscopic shoulder surgery were randomly allocated to receive either SSAB or ISB at a postoperative care unit. The severity of resting and changing position pain was measured using visual analogue scale (VAS) score at 4h, 8h, 12h, 16h, and 24h, postoperatively. Timing of first opioid request, 24h dose requirement, patients' satisfaction rate, and side effects were also recorded. All registered data were analyzed using SPSS software version 23 for Windows (SPSS, Chicago, IL).

 Resting and changing position pain scores were comparable between SSAB and ISB groups in the most time intervals. At 12h, moving and resting pain was significantly lower in ISB than SSAB group, while moving pain was more severe in ISB group at 24h assessment. Patient satisfaction scores were comparable between the two groups except for 12h assessment. Time to first analgesic requirement and total dose of 24h opioid requirement were not significantly different between the two groups.

 Suprascapular plus axillary nerve block could be an effective and safe alternative for interscalene block for pain management after arthroscopic shoulder surgery.

 A variety of skin manifestations have been associated with COVID-19 infection. Acral lesions on hands and feet, closely resembling chilblains, have been reported in association with COVID-19, which are nonspecific. These acro-ischemic painful lesions have been described mainly in asymptomatic and mildly symptomatic pediatric COVID-19 positive patients, without a precise pathogenetic mechanism.COVID-19-induced chilblains may portend an indolent course and a good outcome. In young patients, the IFN-1 response induces microangiopathic changes and produces a chilblain lupus erythematosus-like eruption with vasculitic neuropathic pain features.

 This paper presented a case series of pediatric patients with COVID-19-related skin lesions and neuropathic-like pain.

 Clinical outcomes were collected from 11 patients diagnosed with painful erythematous skin lesions with neuropathic-like pain and positive IgG for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

 It is a mildly symptomatic condition not related to severe pain rates, and it is treated with paracetamol due to the transitory nature of the problem, which provides good results.

 A particular point of interest is skin lesion manifestation as a further indirect sign of SARS-CoV-2 infection. Due to the initial manifestation of chilblains in pauci-symptomatic pediatric patients, they need to be immediately tested and isolated. Chilblains can be considered a clinical clue to suspect SARS-CoV-2 infection and help in early diagnosis, patient triage, and infection control.

 Tissue damage caused by major surgery, such as cesarean section, may lead to a poor host immune response and excessive release of cytokines. These responses may increase the risk of infection, cause postoperative pain, and exert damaging effects on various body organs.

 Anesthesia methods may affect cytokine production after surgery. This study aimed to compare the serum levels of cytokines in general and spinal anesthesia among women undergoing cesarean section.

 Thirty parturients (ASA class I and II) undergoing cesarean section were randomly assigned into two equal groups of spinal anesthesia and general anesthesia. Blood samples were taken for measuring the levels of interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNF-α) before induction of anesthesia and 30 minutes after entering the recovery room.

 In the general anesthesia group, the postoperative serum levels of IL-6 and TNF-α were significantly higher than the corresponding preoperative levels. Significant differences were found between the two groups in the preoperative and postoperative levels of TNF-α. Changes in the IL-6 and TNF-α concentrations were significantly higher in the general anesthesia group as compared to the spinal anesthesia group. However, there was no significant difference in the IL-6:IL-10 and TNF-α: IL-10 ratios between the two groups.

 General anesthesia, as compared to spinal anesthesia, significantly increased the IL-6 and TNF-α levels after cesarean section. Therefore, the spinal anesthesia technique may be a better option for patients undergoing cesarean section.

 This study aimed to assess the effects of using Extracorporeal Shock Wave Therapy (ECSWT) and phonophoresis therapy on pain and neck disability in patients with neck myofascial pain syndrome (MPS).

 Forty eligible patients were randomly divided into two groups of ECSWT (received three sessions of ECSWT, once a week for three weeks) and phonophoresis (received ultrasound using hydrocortisone gel 1% over the trigger point on trapezius muscle, three times a week for three weeks). Patients in both groups received the same stretching exercise program and drug regimen during the intervention.

 Pain and NDI scores in both groups were significantly improved at the end of the treatment and four weeks later. At the end of the treatment, the pain score was similar between the groups. Four weeks after the treatment, the pain score in the ECSWT group was significantly lower than in the phonophoresis group (P-value = 0.030). The NDI score was not significantly different between the groups at the end of the treatment. However, four weeks after the treatment, the NDI score was significantly lower in the ECSWT group than in the phonophoresis group (P-value=0.032). The trend of changes in the pain and NDI scores was not significantly different between the groups.

 Both phonophoresis and ECSWT groups effectively decreased pain and neck disability in patients with MPS, with the superiority of ECSWT with a more lasting effect for a month after the end of the treatment.

 In this study, two cases that demonstrate the importance of bedside echocardiography and hands-off telemedicine technology for diagnosis and intervention in patients with coronavirus disease 2019 (COVID-19) are discussed.

 We report two cases of cardiac emergency associated with COVID-19. Case 1 is a 50-year-old female patient with chronic hypertension and chronic renal failure. Case 2 is a 64-year-old female with atrial fibrillation and recent stroke. Both were admitted to an isolation intensive care unit that was designated specifically to patients with COVID-19.

 During admission, both patients had sudden deterioration characterized by oxygen desaturation and hypotension necessitating inotropic support. As a result, for both patients, bedside echocardiography was performed by the attending intensivist. Echocardiographic findings showed cardiac tamponade and acute pulmonary embolism, respectively, which were confirmed by a cardiologist through telemedicine technology. Proper emergency management was initiated, and both patients recovered well. Limited bedside transthoracic echocardiography had a front-line impact on the treatment and outcome of the two patients with COVID-19. By implementing telemedicine technology, the lives of two patients were saved, demonstrating the significance of telemedicine in isolation intensive care units in the developing countries during the COVID-19 pandemic.

 Neuropathic pain can be caused by several pathologies affecting the nervous system. Peripheral neuralgias may be related to nerve entrapment, traumatic or iatrogenic events, and may also accompany many other diseases. Peripheral nerve stimulation is effective in treating many of these neuralgic syndromes.

 We treated two patients suffering from chronic neuropathic pain of peripheral origin with the implantation of a Bioness (Valencia CA, USA) StimRouter® peripheral nerve stimulation system with follow-up visits at 1 - 3 - 6 - 12 months.

 PNS performed with the StimRouter® system, implanted percutaneously under ultrasound guidance, is safe and effective for patients.
 

 A variety of spinal surgery procedures are performed on patients with different cardiac, vascular, and respiratory comorbidities. Postoperative pain management is a major determinant of hemodynamic and respiratory status in these patients and promotes clinical results, prevents complications, saves health services, and improves the quality of life of patients.

 We compared the effects of dexmedetomidine and remifentanil on pain control after spinal surgery.

 Sixty patients aged 18 - 65 years undergoing spinal surgery were randomized into the two groups of dexmedetomidine and remifentanil. The dexmedetomidine group (group D, n = 30) received dexmedetomidine infusion (0.6 mcg/kg/h), and the remifentanil group (group R, n = 30) received remifentanil infusion (0.1 mcg/kg/min) from induction of anesthesia until extubation. Propofol (1.5 mg/kg) and fentanyl (2mcg/kg) were used to initiate anesthesia, and propofol (100 - 150 mcg/kg/min) was infused to maintain anesthesia. Postoperative pain, hemodynamic parameters, and recovery characteristics were evaluated after surgery.

 The mean pain intensity in the dexmedetomidine group was significantly lower than in the remifentanil group (2.98 ± 1.29 vs. 3.80 ± 1.1; P < 0.001). Hemodynamic changes in the dexmedetomidine group (MAP: 92.60 ± 5.56, HR: 73.07 ± 7) were less, and their condition was significantly more stable than in the remifentanil group (MAP: 93.85 ± 4.78, HR: 79.15 ± 7.03; P < 0.05). The mean arterial oxygen saturation (O2 sat) in the dexmedetomidine group was significantly higher and more stable than in the remifentanil group (98.87 ± 0.51 vs. 97.92 ± 0.46; P < 0.05). The incidence of nausea and vomiting was significantly lower in the dexmedetomidine group compared to the remifentanil group (P < 0.05). The administration of analgesics in the post-anesthetic care unit (PACU) was significantly higher in the remifentanil group than the dexmedetomidine group (P = 0.016).

 Anesthetic maintenance with either dexmedetomidine or remifentanil infusion until extubation provided more smooth and hemodynamically stable conditions, without complications. However, dexmedetomidine provides better analgesia, causes a more stable hemodynamic state, and reduces postoperative nausea-vomiting, shivering, and the need for analgesics.

 Adding dexmedetomidine to bupivacaine has been shown to prolong the analgesic effects of the transversus abdominis plane (TAP) block. However, the optimal dose of this adjuvant drug is unclear.

 Identifying optimal doses of dexmedetomidine added to bupivacaine in the TAP block.

 In this randomized controlled trial, 86 patients candidate for elective open inguinal herniorrhaphy under spinal anesthesia were divided randomly into three groups; low (L), medium (M), and high (H) dose of dexmedetomidine, that finally 80 cases ended the study and were analyzed. At the end of the surgery, the patients underwent ultrasound-guided TAP block. In all patients of the three groups, the analgesic base of the block was 20 mL bupivacaine 0.125% that was supplemented with 0.5, 1, or 1.5 µ/kg of dexmedetomidine in groups L, M, and H, respectively.

 The maximum duration of the block was 4 hours in group L and 8 hours in groups M and H. None of the patients needed to receive analgesic at 0, 2, and 24 hours after the block. The dose of analgesic required in the first 8 hours of the block in groups M and H was less than in group L (P < 0.02). Patients in groups H and M were more satisfied with the block (P < 0.01) and experienced less pain compared with group L (P < 0.01). Drowsiness and sedation were observed in patients up to 4 hours after the TAP block, which was dependent on the dexmedetomidine dose (P < 0.01).

 Based on our results, the optimal dose of supplemental dexmedetomidine could be 1 µ/kg in the TAP block.