Tourniquet-induced Hypertension Research Articles

Combined femoral artery block and femoral nerve block reduces thigh tourniquet-induced hypertension

Study objectiveTourniquet hypertension (TH) is thought to be caused by sympathetically mediated C-fibers in the femoral epicardium following prolonged intraoperative inflation of the tourniquet, and we hypothesized that blocking the femoral artery at the same time as a conventional femoral nerve block would reduce the incidence of TH. DesignA prospective, double-blind, randomized, controlled trial. SettingOperating room and hospital ward in the Third Hospital of Hebei Medical University. PatientsA total of 72 patients receiving high tibial osteotomy under general anesthesia were recruited from June 2022 to September 2022. InterventionsPatients were randomly assigned to receive either a classical femoral nerve block (CFNB) or a modified femoral nerve block (MFNB). Patients in the CFNB group received a 30 mL of 0.5% ropivacaine femoral nerve block and patients in the MFNB group received a 20 mL of 0.5% ropivacaine femoral nerve block combined with a 10 mL of 0.5% ropivacaine femoral artery block. MeasurementsThe primary outcome assessed was the incidence of TH. Data on intraoperative esmolol dosage, analgesic effect, complications and hemodynamics during surgery were also recorded. Main resultsIncidence of TH was significantly higher in the CFNB group compared with the MFNB group (71.88% vs 31.25%, P = 0.002). The systolic blood pressure in the CFNB group was significantly higher than that in the MFNB group at 45, 60, 75 and 90 min after tourniquet inflation (P = 0.029, P = 0.020, P = 0.009, P = 0.007). There was also a significant increase in intraoperative esmolol dosage in the CFNB group (65.63 ± 44.15 vs 22.19 ± 33.74, P < 0.001). Postoperative pain scores and patient satisfaction were not statistically significant between the two groups. ConclusionsThe present study demonstrated that modified femoral nerve block reduced intraoperative esmolol dosage and the incidence of TH.

Efficacy of femoral periarterial block in preventing thigh tourniquet pain: a randomized controlled trial.

Tourniquet pain, described as a dull, tight, poorly localized aching sensation, is common in conscious patients. Although various pain-reduction methods have been implemented, none are completely effective. Femoral periarterial block (FAB) has been shown to attenuate tourniquet-induced hypertension in patients undergoing general anesthesia. We aimed to test the feasibility of FAB in inhibiting thigh tourniquet pain in orthopedic patients under conscious sedation. Forty-two patients (aged 18-64 years and ASA I-II) scheduled for below-knee orthopedic surgeries with an anticipated tourniquet duration of more than 40 min were recruited and received FAB (Group 1) or not (Group 2). The primary outcome was the occurrence of tourniquet pain. The onset time and severity of the tourniquet pain were recorded. Total doses of sedatives and analgesics administered intraoperatively and hemodynamic changes were documented. The occurrence of local anesthetic systemic toxicity was recorded. Kaplan-Meier time-to-event curves indicated an improved tourniquet tolerance and delayed pain onset. Tourniquet pain occurrence was lower in Group 1 than in Group 2 (30% vs. 95.5%, P=0.02). Tourniquet pain onset was delayed in Group 1 (80[67,84] min vs. 58[51.5,60] min, P<0.01). Fewer patients in Group 1 experienced severe pain (3(15%) vs. 18(81.8%), P<0.01), and less hemodynamic changes (2(10%) vs. 12(54.5%), P<0.01). Local anesthetic systemic toxicity was absent. FAB, applied with regional anesthesia in patients undergoing below-knee orthopedic surgeries, could reduce thigh tourniquet pain, stabilize blood pressure and heart rate, and prolong tourniquet duration.

Effect of Ketamine on Tourniquet Induced Hypertension

Objective: To compare the frequency of tourniquet induced hypertension in patients undergoing limb surgeries under general anesthesia with intravenous infusion of ketamine and placebo (saline infusion).&#x0D; Study Design: Comparative prospective study.&#x0D; Place and Duration of Study: Anaesthesia Department, Combined Military Hospital, Rawalpindi Pakistan, from May to Nov 2018.&#x0D; Methodology: Total 80 patients undergoing upper and lower limb surgeries with tourniquet application under general anesthesia were randomly assigned into two equivalent groups. Group A (n=40) received intravenous ketamine 0.1 mg/kg bolus followed by infusion at a rate of 2ug/kg/min while Group B (n=40) received intravenous bolus of normal saline followed by its infusion via infusion pump. Systolic blood pressures were recorded by non-invasive method 30 seconds prior to tourniquet inflation and at 60 mins interval after its inflation. Results were characterized using the descriptive statistics. Mean and standard deviation (SD) were used for quantitative variables while frequency and percentages for qualitative variables. The p-value &lt;0.05 was considered as significant.&#x0D; Results: Tourniquet induced hypertension was found in 2 (5.0%) group A patients and 11 (27.50%) group B patients with statistically significant p-value of &lt;0.05. Visual analogue scale score was slightly higher in the Saline group, but the result was statistically not significant (p=0.32).&#x0D; Conclusion: Ketamine infusion reduces the occurrence of tourniquet induced hypertension in patients undergoing surgeries with tourniquet application.

Comparison of bolus administration effects of lidocaine on preventing tourniquet-induced hypertension in patients undergoing general anesthesia: a randomized controlled trial.

BackgroundThis study assessed the effect of a single bolus administration of lidocaine on the prevention of tourniquet-induced hypertension (TIH) and compared the effect of lidocaine to that of ketamine in patients undergoing general anesthesia.MethodsThis randomized, controlled, double-blind study included 75 patients who underwent lower limb surgery using a tourniquet. The patients were administered lidocaine (1.5 mg/kg, n = 25), ketamine (0.2 mg/kg, n = 25) or placebo (n = 25). The study drugs were administered intravenously 10 min before tourniquet inflation. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were measured before tourniquet inflation, after tourniquet inflation for 60 min at 10 min intervals, and immediately after tourniquet deflation. The incidence of TIH, defined as an increase of 30% or more in SBP or DBP during tourniquet inflation, was also recorded.ResultsSBP, DBP, and HR increased significantly over time in the control group compared to those in the lidocaine and ketamine groups for 60 min after tourniquet inflation (P < 0.001, P < 0.001, and P = 0.007, respectively). The incidence of TIH was significantly lower in the lidocaine (n = 4, 16%) and ketamine (n = 3, 12%) group than in the control group (n = 14, 56%) (P = 0.001).ConclusionSingle-bolus lidocaine effectively attenuated blood pressure increase due to tourniquet inflation, with an effect comparable to that of bolus ketamine.

Tourniquet Complications in an Upper Extremity Orthopedic Surgery Patients

Abstract An arterial tourniquet is a pneumatic device consisting of an inflated cuff connected to a supply of compressed gas. The most common use for these tourniquets is in surgical procedures on the extremities, where the tourniquet is very useful in optimizing the operating conditions by creating a bloodless surgical field. However, the exsanguination process followed by ischemia will result in physiological problems with local and systemic consequences. The patient in the case to be discussed is a 54-year-old woman with a diagnosis of implant loosening et causa nonunion left Montegia fracture who was scheduled for implant revision surgery. From these cases, it is possible that the patient experienced tourniquet-induced hypertension, which is one of the systemic complications that can arise due to the use of the tourniquet. It is said that tourniquet-induced hypertension is often difficult to control and is resistant so it is difficult to lower it. Emerging hypertension may not present a significant problem in young, noncomorbid patients, but in these patients with comorbid of hypertensive heart disease (HHD), elevated blood pressure can be very detrimental. Preoperative ketamine, clonidine, or lidocaine has been used to prevent tourniquet pain, which can lead to increased arterial pressure that is difficult to control. The anesthetist is also obliged to monitor the duration and pressure applied by the tourniquet so that it is not excessive so that detrimental complications can be prevented.

Femoral artery block (FAB) attenuates thigh tourniquet-induced hypertension: a prospective randomized, double-blind, placebo-controlled trial

IntroductionProlonged tourniquet inflation during surgery frequently leads to tourniquet hypertension (TH), which is thought to arise from compression of A-δ fibers leading to sympathetically mediated C fiber activation. In the...

Combined Sciatic-Lumbar Plexus Block with General Anesthesia: Efficacy in Preventing Tourniquet-Induced Hemodynamic Changes

Background: Pneumatic arterial tourniquet is a utilized strategy in limb surgeries to provide bloodless field to facilitate surgical procedure. Be that as it may, arterial tourniquet has numerous injurious impacts including hemodynamic changes and tourniquet-induced pain which sometimes can be severe and intolerable. Objectives: Our primary aim was to assess the impact of performing “Lumbar Plexus Block and sciatic nerve block” with General Anesthesia (GA) on the degree of arterial tourniquet-induced hemodynamic effects. On the other hand, our secondary aims were: amount of postoperative analgesic prerequisites, patient satisfactory score and documented side effects. Settings and Design: Ain Shams University, Orthopedic operating theatre; a prospective, randomized, double-blind study. Methods and Material: The physical status of 50 patients (both sexes) including I and II patients from American Society of Anesthesiologists, whose ages are from 20 - 40 years, is not so ideal when they are undergoing elective knee Arthroscopy. The duration lasts no more than ninety minutes under GA with application of tourniquet. Patients were allotted haphazardly to one of two groups. In Group C (Control group): Only GA. In Group B: LPB and sciatic nerve block were performed just before GA administration. Intraoperative hemodynamics was recorded at specific timings. Results: Incidence of tourniquet induced hypertension (TIH) was markedly less with Group B at: forty five, sixty, seventy five mins after tourniquet inflation and just before tourniquet deflation. Also, the total ketorolac consumption during first 24 hours of postoperative period was significantly less with Group B (p < 0.001). Finally, patient satisfaction was significantly higher in Group B. Conclusions: Combined Sciatic-Lumbar plexus blocks when combined with general anesthesia were very effective in attenuating TIH.

Evaluation of effect of intravenous Magnesium Sulfate infusion on tourniquet induced hypertension and pain in arthroscopic knee surgery patients under epidural anesthesia

ObjectiveThis prospective randomized, double blind controlled study was designed to evaluate the effect of Intravenous (i.v) magnesium sulfate infusion on attenuation of tourniquet induced hypertension (TIH) and tourniquet pain and also its effect on postoperative analgesia in patients undergoing arthroscopic knee surgery under epidural anesthesia.Patients and methodsSeventy ASA I and II patients were scheduled for arthroscopic knee surgery with tourniquet under epidural anesthesia. Patients were allocated randomly into two equal groups (n = 35): Magnesium (Mg group) received a bolus dose of IV magnesium sulfate 30 mg/kg in 50 ml saline over 10 min, followed by infusion 10 mg/kg/h and control group received iv saline. Systolic and Diastolic blood pressure (SBP, DBP) and Heart rate (HR) were measured at baseline (before anesthesia), after epidural anesthesia, then every 10 min after the tourniquet inflation, and 1, 5, 10, and 30 min after deflation with recording incidence of (TIH), tourniquet pain, and total iv fentanyl consumption (was given iv 1 ug/kg with tourniquet pain); postoperative Visual Analogue Scale (VAS) score was assessed at 1, 2, 4, 8, 12, 18, and 24 h, postoperative pethidine consumption (given iv 0.5 mg/kg if VAS > 3) was recorded, and serum magnesium was measured preoperatively and at 6 and 24 h postoperatively.ResultsSBP, DBP and HR were significantly higher in the control group than in the Mg group (p < 0.001) after 50 min of inflation. The number of patients who developed TIH and tourniquet pain was significantly lower in Mg group compared to control group 3(8.57%) vs 12(34.28%) (p < 0.05), with significantly shorter time to feel pain in control group 48 ± 8 min versus 71 ± 7 min (p < 0.001). Intraoperative fentanyl requirements were significantly higher in control group compared to Mg group (p < 0.001). Mg group had significantly lower postoperative VAS scores and pethidine consumption (p < 0.001) and significantly longer time to first request of postoperative analgesia compared to control group (p < 0.001). Postoperative serum magnesium was significantly higher in Mg group at 6 h postoperative (p < 0.001).ConclusionIn patients undergoing arthroscopic knee surgery under epidural anesthesia, IV magnesium sulfate in a dose of 30 mg/kg, followed by 10 mg/kg/h infused before tourniquet inflation could reduce TIH, and tourniquet pain with reduction in intraoperative IV fentanyl and postoperative pethidine requirements.

Role of Low Dose Preoperative Dexmedetomidine in Preventing Tourniquet Induced Hypertension in Paediatric Orthopaedic upper Limb Surgeries during General Anaesthesia

Role of Low Dose Preoperative Dexmedetomidine in Preventing Tourniquet Induced Hypertension in Paediatric Orthopaedic upper Limb Surgeries during General Anaesthesia

Intraoperative lidocaine infusion attenuates tourniquet induced hypertension in patients undergoing anterior cruciate ligament reconstruction under general anesthesia

ObjectiveThis randomized, double blind, controlled study was designed to test whether the intraoperative use of intravenous lidocaine bolus followed by infusion would attenuate the tourniquet induced hypertension (TIH) in patients undergoing anterior cruciate ligament reconstruction (ACLR) under general anesthesia.Methods76 patients were randomly allocated into two equal groups. Lidocaine group (group L), in which patients received lidocaine 2% 1 mg/kg IV bolus after induction of anesthesia followed by lidocaine infusion (2 mg/kg/h) and placebo group (group P), in which patients received equal volumes of saline. Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded before induction of anesthesia, before tourniquet inflation (baseline value), every 15 min after tourniquet inflation, and after tourniquet deflation. The number of patients who developed TIH was recorded and total amount of propofol and fentanyl used intraoperative was recorded.ResultsSBP, DBP and HR were significantly less after tourniquet inflation in group L compared to group P in most of the time periods after tourniquet inflation (p value < 0.05), the number of patients developed TIH was significantly less in group L compared to group P (26% in group L compared to 52.6% in group P) (p value 0.019), and the total amount of propofol and fentanyl used intraoperative was significantly less in group L compared to group P (p value 0.000).ConclusionIntraoperative use of lidocaine bolus (1 mg/kg), followed by infusion (2 mg/kg/h), started 10 min before tourniquet inflation attenuated the TIH in patients undergoing anterior cruciate ligament reconstruction under general anesthesia.

Influence of Dexmedetomidine on the Tourniquet Related Responses in Hypertension Patients Receiving Unilateral Knee Arthroplasty under General Anesthesia

This study aimed to investigate the influence of dexmedetomidine (DEX) on the tourniquet related responses in hypertension patients receiving unilateral knee arthroplasty (UKA) under general anesthesia. Results showed that the incidence of tourniquet induced hypertension (TIH), hemodynamics, MAC and EtSEV in DEX group were significantly lower than those in control group, regardless of hypertension. However, significant differences in TIH, hemodynamics, minimum alveolar concentration (MAC) and end-tidal sevoflurane (EtSEV) were not observed between hypertension patients and non-hypertension patients in both control group and DEX group. Moreover, oxygen index (OI) and respiratory index (RI) remained unchanged after deflation and DEX failed to affect OI and RI within 30min after deflation, regardless of hypertension. Taken together, DEX may significantly improve the hemodynamics, which is independent of pre-existing hypertension.

Tourniquet-induced cardiovascular responses in anterior cruciate ligament reconstruction surgery under general anesthesia: Effect of preoperative oral amantadine

ObjectiveThe aim was to test the effect of amantadine, an NMDA antagonist, on tourniquet induced cardiovascular responses under general anesthesia.MethodIn a randomized, double blind, placebo-controlled study; thirty adult male patients with ASA physical status I or II, aged 18–50 years underwent anterior cruciate ligament reconstruction with a tourniquet under general anesthesia, were divided to receive either oral amantadine 200 mg capsule in the evening before surgery and 200 mg capsule 60 min before surgery (group A) or placebo capsules (group P). Heart rate, systolic and diastolic blood pressures were recorded (before induction of anesthesia, every 15 min after tourniquet inflation, before tourniquet deflation, and 10 min after tourniquet deflation). Incidence of tourniquet-induced hypertension, and postoperative tramadol consumption were also recorded.ResultsSystolic and diastolic pressures significantly increased in both groups compared to baseline values (P < 0.05) at 15, 30, 45, 60, 75 min after tourniquet inflation, and before tourniquet deflation with significantly lesser increase with amantadine compared to placebo at 45, 60, and 75 min after tourniquet inflation (P < 0.05). Heart rate significantly increased at 45, 60, and 75 min after tourniquet inflation in both groups compared to baseline values (P < 0.05) with significantly lesser increase with amantadine compared to placebo (P < 0.05). Development of tourniquet induced hypertension was less with amantadine (5 out of 15) than with placebo (8 out of 15).The total tramadol consumed during the first 24 h postoperative was significantly less with amantadine compared to placebo (P < 0.05).ConclusionPreoperative oral amantadine reduced tourniquet induced hypertension and postoperative analgesic requirements in anterior cruciate ligament reconstruction surgery under general anesthesia.

İntravenöz Rejyonel Anestezi Sırasında Turnike ile İndüklenen Hipertansiyon Üzerinde Kalsiyum Kanal Blokerleri ve Beta Blokerlerin Etkilerinin Karşılaştırılması

İntravenöz Rejyonel Anestezi Sırasında Turnike ile İndüklenen Hipertansiyon Üzerinde Kalsiyum Kanal Blokerleri ve Beta Blokerlerin Etkilerinin Karşılaştırılması

Good vagal tone, a tourniquet and dexmedetomidine: Recipe for disaster.

Sir, Arthroscopic repairs of the cruciate ligaments of the knee are fairly common place surgeries. Both anterior and posterior ligaments are commonly repaired at the same sitting, resulting in prolonged surgery and consequently, tourniquet time. These injuries are common among young, fit athletic individuals. The vagal tone may be increased in these individuals.[1] Though many patients undergoing surgery are curious about the procedure and refuse sedation in order to watch the procedure live, some are quite anxious and demand sedation. A 31-year-old footballer was posted for arthroscopic repair of both ligaments of the right knee. The patient (American society of Anaesthesiologists physical status I) though was willing for a spinal anaesthetic, requested deep sedation as he was very anxious. Baseline heart rate was 55/min and non-invasive blood pressure (NIBP) 113/71 mm of Hg. Spinal anaesthesia was administered with 17.5 mg of bupivacaine 0.5% heavy plus 25 μg of fentanyl in sitting position and midline projection via a 26 gauge Quincke needle. Sensory block height achieved was till T6 after 5 min. A pneumatic tourniquet was applied around the thigh and inflated to 300 mmHg. Midazolam 3 mg intravenous (IV) was administered just before incision and patient became drowsy but remained anxious and restless. Dexmedetomidine IV (Xamdex®100 μg/ml, 2 ml ampoule, Abbott) was started at 0.5 μg/kg/h, avoiding the loading dose as midazolam had already been given. The patient became sedated in about 10 min. Oxygen was started via polymask. The surgery prolonged beyond the default tourniquet alarm time of 60 min; the surgeon needed an additional hour and the tourniquet time was increased accordingly. The patient remained well sedated; the heart rate had dipped to about 47–52 beats/min, but the blood pressure (BP) remained stable. After 2 h, the surgeon was requested to deflate the tourniquet temporarily but disagreed since he had only a few minutes to complete the procedure. Dexmedetomidine infusion was discontinued at this time. However, completion took another 30 min and the tourniquet was deflated at 150 min. Seconds after the deflation, the patient's heart rate started dropping and when it reached 30 beats/min, injection atropine 0.6 mg IV was administered. The patient, who had awakened and become communicative after the dexmedetomidine infusion was terminated, became unresponsive. This was followed by sudden asystole on the monitor, as can be seen from the photograph of the monitor trend screen [Figure 1].Figure 1: Photograph of monitor trend screen showing asystolic arrest (yellow arrow) and recoveryQRS complexes reappeared after about 10 s and after about 30 s heart rate was 60/min. The patient became responsive and oriented, with no recall of events. After 1 min, the patient was calm, cooperative and completely stable. There was no NIBP reading at the point of asystole, but readings, while the heart rate improved, were in normal range. Post-procedure, the patient was monitored for 24 h and was discharged after 3 days. Young athletic persons manifest high vagal tone with low resting heart rates. Neuraxial blocks may also cause bradycardia and hypotension. Dexmedetomidine also causes significant bradycardia. Though prolonged use of the tourniquet is associated with a slow rise in heart rate and BP, this effect may be obtunded by other factors such as dexmedetomidine and antihypertensive drug use. Lu et al.[2] demonstrated that pre-operative dexmedetomidine prevents tourniquet-induced hypertension in patients under general anaesthesia. In our case, basal heart rate was low, but no bradycardia or hypotension occurred after spinal anaesthetic. Though dexmedetomidine infusion brought down the heart rate by about 5–7 beats, both heart rate and NIBP remained stable. Tourniquet release is associated with sudden haemodynamic changes including rate and rhythm changes, hypotension, pulmonary oedema,[3] pulmonary embolism,[45] and cardiac arrest.[67] In this case, the prolonged tourniquet for 150 min, along with the basal vagal tone and the continuing effect of the dexmedetomidine led to the asystolic arrest; fortunately, in the absence of pre-existing heart disease, response to intervention was prompt. This combination should be avoided; if inescapable, constant monitoring and use of emergency drugs and equipment can save the day.

Preoperative small-dose ketamine (Ket) postpones, but dose not prevent, the onset of tourniquet-induced hypertension (TIH) and increase of low-to high-frequency ratio of heart rate variability (LF/HF)

Preoperative small-dose ketamine (Ket) postpones, but dose not prevent, the onset of tourniquet-induced hypertension (TIH) and increase of low-to high-frequency ratio of heart rate variability (LF/HF)

Preoperative dexmedetomidine prevents tourniquet-induced hypertension in orthopedic operation during general anesthesia

This study was a double-blinded randomized control trial designed to investigate the hemodynamic effects of dexmedetomidine on prolonged tourniquet inflation. Thirty-seven patients scheduled for elective orthopedic surgery of the lower limb under general anesthesia were recruited. They were randomly assigned to receive intravenous dexmedetomidine (DEX, 0.5 μg/kg; n = 18) or normal saline (CON; n = 19) before tourniquet inflation. Arterial blood pressure and heart rate were recorded every 10 minutes until 60 minutes after the start of tourniquet inflation and again immediately after deflation. In the DEX group, arterial pressure was not significantly changed, but in the CON group arterial pressure was significantly increased at 40, 50, and 60 minutes after the start of tourniquet inflation. Development of more than 30% increase in arterial pressure during tourniquet inflation was more frequent in the CON group than in the DEX group. Preoperative intravenous dexmedetomidine could therefore prevent tourniquet-induced hypertension in patients undergoing general anesthesia.

Opioid-induced hyperalgesia: low-dose ketamine does work for some orthopaedic problems already

Editor—I read with interest the original article and accompanying editorial on opioid-induced hyperalgesia (OIH).1Minville V Fourcade O Girolami J-P Tack I Opiod-induced hyperalgesia in a mice model of orthopaedic pain: preventive effect of ketamine.Br J Anaesth. 2010; 104: 231-238doi:10.1093/bja/aep363Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar 2Colvin LA Fallon MT Opioid-induced hyperalgesia: a clinical challenge.Br J Anaesth. 2010; 104: 125-127doi:10.1093/bja/aep392Abstract Full Text Full Text PDF PubMed Scopus (54) Google Scholar There are already clinical studies, which support some of the findings, although the type of pain may be slightly different. I have used low-dose ketamine, usually 0.15 mg kg−1, for the prevention of tourniquet-induced hypertension and pain3Segerdahl M Ekblom A Sollevi A The influence of adenosine, ketamine and morphine on experimentally induced ischemic pain in healthy volunteers.Anesth Analg. 1994; 79: 787-791doi:10.1213/00000539-199410000-00029Crossref PubMed Scopus (98) Google Scholar for a number of years. Low-dose ketamine is also successful at reducing morphine requirements after anterior cruciate reconstruction surgery.4Menigaux C Fletcher D Dupont X Guignard B Guirimand F Chauvin Ml The benefits of intraoperative small-dose ketamine on postoperative pain after anterior cruciate ligament repair.Anesth Analg. 2000; 90: 129-135doi:10.1097/00000539-200001000-00029Crossref PubMed Scopus (191) Google Scholar For orthopaedic lower limb arthroplasty surgery, I add ketamine 0.15 mg kg−1 to my analgesic mixture. I think that these clinical studies are good supporting evidence for the work done by Minville and colleagues.1Minville V Fourcade O Girolami J-P Tack I Opiod-induced hyperalgesia in a mice model of orthopaedic pain: preventive effect of ketamine.Br J Anaesth. 2010; 104: 231-238doi:10.1093/bja/aep363Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar I agree that more good-quality clinical studies are needed, and there is an urgent requirement for S-ketamine to be made available to anaesthetists in the UK. Editor—We thank Dr Griffiths for his interesting observations on the clinical use of ketamine. There is indeed an increasing number of clinical studies on the use of ketamine, with opioid-sparing effects in the postoperative period.5Berti M Baciarello M Troglio R Fanelli G Clinical uses of low-dose ketamine in patients undergoing surgery.Curr Drug Targets. 2009; 10: 707-715doi:10.2174/138945009788982496Crossref PubMed Scopus (33) Google Scholar A Cochrane review of perioperative ketamine deemed 37 randomized controlled trials, with a total of 2240 patients, to be of sufficient quality to include in their analysis—of these 27 trials found that subanaesthetic doses of ketamine were effective in pain control, reducing opioid requirements, and with minimal adverse effects.6Bell RF Dahl JB Moore RA Kalso E Perioperative ketamine for acute postoperative pain. 2006doi:10.1002/14651858.CD004603.pub2Crossref Google Scholar It seems clear from this that ketamine, or perhaps other N-methyl d-aspartate (NMDA) receptor antagonists, has a role in perioperative management. S-ketamine may have a better side-effect profile, or other agents, selective for different subtypes of the NMDA receptor, might have improved clinical utility. The specific role of ketamine in preventing OIH is also of interest: whether its site of action is in the spinal cord, where we know central sensitization involving the NMDA receptor occurs, or in higher centres does require further study. Clinical imaging studies have certainly demonstrated effects on pain processing areas in the brain, but the clinical significance of this is not yet understood.7Sprenger T Valet M Woltmann R et al.Imaging pain modulation by subanesthetic s-(+)-ketamine.Anesth Analg. 2006; 103: 729-737doi:10.1213/01.ane.0000231635.14872.40Crossref PubMed Scopus (57) Google Scholar 8Rogers R Wise RG Painter DJ Longe SE Tracey I An investigation to dissociate the analgesic and anesthetic properties of ketamine using functional magnetic resonance imaging.Anesthesiology. 2004; 100: 292-301doi:10.1097/00000542-200402000-00018Crossref PubMed Scopus (102) Google Scholar By using a combination of approaches to the problem, with evidence from basic science studies, volunteer and clinical imaging studies, and good-quality clinical trials, it may be possible to develop clinical strategies to address OIH and minimize its impact on delivering effective analgesia in a variety of settings. None declared. L. A. Colvin* M. T. Fallon Edinburgh, UK E-mail: [email protected]

Effect of Stellate Ganglion Block on Tourniquet Induced Hypertension

Background: Tourniquet induced hypertension, defined as a more than 30% increase in either systolic or diastolic arterial pressure in patients with a tourniquet inflated for at least an hour, may develop despite adequate anesthesia for surgical procedure. The mechanism is uncertain. We investigated the effect of stellate ganglion block (SGB) on tourniquet induced arterial pressure and heart rate changes. Methods: Twenty-two patients of ASA physical status class 1 and 2, scheduled for lower extremity surgery using a tourniquet, were randomly assigned into two groups (SGB group, Control group). SGB was done before induction, and anesthesia was maintained with 1.5-2.0 vol% sevoflurane and 50% N20 in O2 with endotracheal intubation. The changes of heart rate, systolic, diastolic blood pressure, end tidal CO2 and end tidal sevoflurane concentration were measured before induction, 10 minutes after induction, 10, 30, and 60 minutes after tourniquet inflation, just before tourniquet deflation and 10 minutes after tourniquet deflation. Results: Heart rate increased significantly at 10 minutes after induction and 10 minutes after tourniquet inflation compared to before induction in SGB group. In both groups, systolic arterial pressure increased significantly just before tourniquet deflation compared to before induction, and there was no difference between groups. In SGB group, diastolic arterial pressure decreased significantly compared to control group at 30 minutes after tourniquet inflation. Conclusions: Preoperative stellate ganglion block was not effective in blunting tourniquet induced hypertension. (Korean J Anesthesiol 2007; 52: 409~14)

Magnesium Sulphate Attenuates Tourniquet-induced Hypertension and Spinal c-fos mRNA Expression: A Comparison with Ketamine

Magnesium and ketamine are well-known N-methyl-D-aspartic acid receptor antagonists. The aim of this study was to determine whether magnesium, in comparison with ketamine, attenuates tourniquet-induced hypertension and spinal c-fos mRNA expression. Rats were divided into four treatment groups: normal (baseline for c-fos mRNA expression); control (saline injection); magnesium injection; and ketamine injection. Arterial blood pressure and c-fos mRNA expression at 60 min were higher in the control than in the magnesium and ketamine groups. Human patients under sevoflurane-oxygen/nitrous oxide anaesthesia were also assigned to receive similar treatments. In humans, arterial blood pressure was increased in the control group at 50 min and thereafter compared with the magnesium and ketamine groups; the magnesium and ketamine groups did not differ. Magnesium and ketamine are equally effective in attenuating tourniquet-induced hypertension and spinal c-fos mRNA expression, suggesting that this effect may be due to reduced pain transmission.

Effect of Intraoperative Continuous I.V. Fentanyl on Tourniquet Induced Cardiovascular Changes and Postoperative Preemptive Analgesia in Total Knee Replacements

Background: It is difficult to treat tourniquet-induced hypertension despite adequate anesthesia, and the mechanism of that is not known. And it may be possible that intraoperative continuous infusion of opioid induces preemptive analgesia postoperatively. We investigated the effect of intraoperative continuous i.v. fentanyl on tourniquet induced cardiovascular changes and postoperative preemptive analgesia in total knee replacements. Methods: Sixty patients were randomly assigned to two groups; In study group (1.5 loading and 0.5 continuous infusion of fentanyl before skin incision and tourniquet inflation) and control group (no treatment). Anesthesia was maintained with enflurane (1-2 MAC) and 50% nitrous oxide in oxygen. Arterial pressure and heart rate were compared between two groups. They received postoperative pain treatment with patient-controlled analgesia (PCA) with fentanyl during the postoperative 48 hours after total knee replacement. Visual analog scale (VAS) scores at either rest or movement were used to assess pain. Total fentanyl dose delivered, number of PCA requests, supplemental analgesics, overall satisfaction score and adverse events were evaluated. Results: There were no significant differences between the two groups on cardiovascular changes by tourniquet induced pain effect. VAS, PCA delivered dose and PCA demands at movement in the 24-48 hour decreased in study group compared with control group (P