Tourniquet In Patients Research Articles

Effect of needle types and diameters using in spinal anesthesia on optic nerve sheath diameter: Prospective randomized study.

This prospective randomized study aimed to investigate the impact of needle types and diameters used in spinal anesthesia (SA) on optic nerve sheath diameter (ONSD) in patients undergoing lower extremity orthopedic surgery. Patients were randomly assigned to 3 groups based on the needle type and size used for SA: Group 25w (25 gauge Whitacre needle), Group 27q (27 gauge Quincke needle), and Group 25q (25 gauge Quincke needle). Initially, 165 patients (55 in each group) were enrolled, with 146 patients ultimately included in the analysis (Group 25w, n = 49; Group 27q, n = 48; Group 25q, n = 49). ONSD measurements were conducted using ultrasound guidance at 5 time points: T0 (pre-SA), T1 (5 minutes post-SA), T2 (5 minutes post-tourniquet inflation), T3 (5 minutes post-tourniquet deflation), and T4 (24 hours post-operation). Additionally, oxygen saturation, systolic arterial pressure, mean arterial pressure, diastolic arterial pressure, and heart rate were recorded at these time points. Analysis of ONSD measurements revealed no significant differences among the groups at time points T0,T1,T2, and T4 (P = .7293, P = .4428, P = .3676, and P = .3667, respectively). However, at T3, ONSD values were significantly higher in Group 27q compared to Group 25q (P = .0325). Across all groups, the mean ONSD values measured post-tourniquet release (T3) were higher than those at T0,T2, and T4 (P < .001 for all). The incidence of nausea was similar among the groups, and no cases of headache or visual impairment were reported within the initial 24 hours post-surgery. In conclusion, our study suggests that while subarachnoid injection and tourniquet inflation do not impact intracranial pressure (ICP), tourniquet deflation leads to an increase in ICP during lower limb surgery under SA. Therefore, caution should be exercised when using a tourniquet in patients at risk of elevated ICP.

Summary of the best evidence for the safe use of pneumatic tourniquet in limb surgery

PurposeTo retrieve, evaluate, and summarize the best available evidence regarding the safe use of pneumatic tourniquet in patients undergoing Limb surgery, providing guidance for preoperative assessment, operation methods and precautions, complication prevention and treatment in clinical practice.MethodsUsing the PIPOST tool, we formulated an evidence-based question, conducted searches in relevant Chinese and international databases and websites for clinical decisions, guidelines, evidence summaries, systematic reviews, and expert consensus on the use of limb surgical tourniquets. The search was limited to literature published until September 30, 2023. Quality assessment and evidence extraction were performed on eligible documents.ResultsThis study included a total of 13 articles, including 2 clinical decision-making articles, 3 guidelines, 5 expert consensus articles, 1 standard and 2 systematic reviews. A total of 34 best pieces of evidence recommendations were summarized across 10 aspects, including indications and contraindications for the use of pneumatic tourniquets, preoperative evaluation of operators, selection and placement of tourniquet cuffs, tourniquet inflation, monitoring during inflation, tourniquet deflation, common complications and prevention, equipment safety, documentation, and training and education.ConclusionThe best evidence summarized in this study can provide reference for clinical medical staff to safely use pneumatic tourniquets, but in clinical practice, targeted selection and application of evidence should be combined with specific situations to improve the safety and hemostatic effect of pneumatic tourniquet use.

Delayed Diagnosis of Ischemia after Popliteal Artery Injury during total Knee Arthroplasty

Over 600,000 TKA are performed annually in the USA. Injuries to the popliteal artery are unusual, estimated to occur in less than 0.2% of cases [1-3]. Three mechanisms of injury have been reported, the use of a pneumatic tourniquet in patients with advanced atherosclerosis [4], sharp, direct trauma to the vessels and stretching or kinking of the artery when the knee is manipulated [5,6]. It is generally believed that popliteal artery occlusion rapidly causes acute ischemia after popliteal artery occlusion because of the paucity of collaterals. Cases of acute ischemia after TKA that slowly evolve and that have been diagnosed and treated on a delayed basis have been rarely reported [3]. This may be because delays in diagnosis frequently result in major morbidity and litigation.

Trans tibial amputation with or without a tourniquet in patients with diabetic foot infection and peripheral vascular disease: Comparison of postoperative outcomes.

Background: Transtibial amputation (TTA) due to complications of diabetic foot infection (DFI) or peripheral vascular disease (PVD) is a high-risk procedure in fragile patients. The risks of reoperation, blood loss requiring blood transfusion, and mortality are high. The use of a tourniquet in this procedure is controversial and scarcely reported. Objective: this study aimed to compare the outcomes of TTAs with or without a tourniquet in a single tertiary medical center. Methods: We retrospectively identified all patients who had undergone TTA in our institution (1/2019-1/2020) and included only those who underwent the procedure due to complications of DFI or PVD (n = 69). The retrieved data included demographics, comorbidities, ASA score, the use of a tourniquet, operation duration, pre- and postoperative hemoglobin levels, administration of blood transfusions, hospitalization length, surgical site infection and 60-days reoperation and mortality rates. Results: TTA with a tourniquet was superior to TTA without a tourniquet in reducing the average operation length by 11 min (p = 0.05), the median postoperative hospitalization by 6days (p = 0.04), and the use of blood transfusions (odds ratio [OR] = 0.176, 95% confidence interval [CI]: 0.031-0.996). Conclusions: Our findings demonstrated advantages in operative time, hospitalization length, and blood transfusion requirement for TTA with a tourniquet compared to TTA without a tourniquet.

Reappraisal of Limited Duration Tourniquet in Total Knee Arthroplasty: A Double-Blinded RCT.

The majority of arthroplasty surgeons use a full duration of tourniquet while doing total knee arthroplasty. Recent literature suggests clinical dilemma about superior function with limited duration use of a tourniquet. The purpose of this study is to evaluate the time-dependent effects and clinical outcome of tourniquet in patients undergoing total knee arthroplasty (TKA) and to assess the incidence of adverse vascular events of the limb in TKA. This study is the first of its kind to evaluate all the serious vascular events prospectively. Sixty participants who underwent TKA in the duration of 1.5years at a large single tertiary care centre were recruited and randomly allocated in two groups: Full duration tourniquet (n = 30) and tourniquet only during cementation (n = 30). All patients underwent preoperative and postoperative arterial and venous Doppler to evaluate the presence of thrombosis. The operative duration, blood loss, and clinical outcome (visual analogue scale, active knee range of motion, Knee Society score, and duration of stay) were recorded. The incidence of vascular complications was not statistically significant in either group (P = 0.99). Tourniquet during cementation only group exhibited decreased postoperative pain on days 1, 2, and 3 (P < 0.01). But postoperative knee active range of motion was the same between the two groups with no significant postoperative complications. Tourniquet use only during cementation could result in faster recovery and less pain during the early rehabilitation period with no influence over the incidence of serious vascular events. AIIMS/IEC/2018/475. This study was approved by the Research Ethics Committee at All India Institute of Medical Sciences, Jodhpur and was carried out at AIIMS (Jodhpur), India.

O42: THE ROLE OF TOURNIQUETS IN TRANSTIBIAL AMPUTATION FOR PERIPHERAL VASCULAR DISEASE: A SYSTEMATIC REVIEW &amp; META-ANALYSIS

Abstract Introduction The use of lower limb tourniquets is traditionally discouraged in severe atherosclerotic disease. However, blood loss and increased transfusion requirements are associated with post-operative morbidity in patients undergoing major lower limb amputation. The aim of this systematic review is to summarise and pool the available data to determine the impact of tourniquet application when performing trans-tibial amputation for peripheral vascular disease. Method This systematic review was conducted according to PRISMA guidelines. A systematic search of Medline, Embase and Cochrane Library was undertaken for articles which compared the use of a tourniquet versus no tourniquet in patients undergoing trans-tibial amputation for peripheral vascular disease. The main outcomes included intra-operative blood loss, post-operative transfusion requirement, need for revision surgery and 30-day mortality. Result Four studies met the inclusion criteria for quantitative analysis with a total of 267 patients. A tourniquet was used in 130 patients. Both groups were matched for age, gender, co-morbidities and pre-operative haemoglobin. In patients undergoing trans-tibial amputation, tourniquets were associated with significantly lower intra-operative blood loss (Mean difference= -147.6mls; P=0.03) and lower transfusion requirements (pooled odds ratio (OR), 0.12, p=0.03). The need for stump revision (OR, 0.7; p=0.48), proceeding to transfemoral amputation within 30 days (OR, 0.67; p=0.25) and 30-day mortality (OR, 0.65; p=0.41) all favoured tourniquet use but the differences were not found to be significant. Conclusion Tourniquets can reduce intra-operative blood loss and transfusion requirements in patients undergoing trans-tibial amputation without increasing ischaemic complications and need for revision surgery. Take-home message Tourniquets are safe to use in trans-tibial amputation for severe peripheral vascular disease and can reduce intra-operative blood loss without increasing ischaemic complications.

Effect of prolonged venostasis on lipid profile parameters among apparently healthy University students: A case-control study in Ghana

Background: The effect of prolonged tourniquet application on lipid profile parameters (total cholesterol, triglyceride, high density lipoprotein cholesterol (HDL-c) and low density lipoprotein cholesterol (LDL-c)) among healthy students in the University of Cape Coast was assessed in this study. Methods: A total of 30 participants were sampled and venous blood was taken from both arms at different duration of tourniquet application. Blood was allowed to clot, centrifuged and serum separated and stored until assay. Lipid profile parameters were measured using the enzymatic techniques with the aid of a spectrophotometer. Lipid parameters were expressed in mmol/L. The relationship between the concentrations was analyzed using GraphPad Prism version 6.0. Results: The mean serum levels of total cholesterol and HDL-c were significantly (p&lt;0.05) elevated after long duration (13.44±2.40 s) of tourniquet application compared to short duration (11.20±0.38 s) of tourniquet application. Despite the fact that the serum levels of triglyceride and LDL-c increased after long duration of tourniquet application compared to short duration, the difference was not significant (p&gt;0.05). There was significant % mean differences of 7.0% (p&lt;0.0001) and 11.2% (p=0.0082) in the concentrations of total cholesterol and HDL-c respectively following prolonged tourniquet application of 120-180 s. A significant increase of up to 7% (5.01±0.04, 5.352±0.05, p&lt;0.0001) and 11% (2.41±0.07, 2.674±0.07, p=0.0082) in the concentrations of total cholesterol and HDL-c respectively was also recorded. Conclusion: Prolonged venostasis has a direct effect on the concentration of serum total cholesterol and HDL-c but not triglyceride and LDL-c. Nonapplication of tourniquet in patients with prominent veins, the application of standardized external pressure as well the early release of tourniquet after needle insertion in the vein should be followed during sample taking for lipid profile. Annals of Medical Laboratory Science (2021) 1(1), 1 - 7

Effect of Intravenous Ibuprofen on Ischemia-Reperfusion Injury Following Perioperative Tourniquet in Patients Undergoing Total Knee Arthroplasty

Oxidative stress occurs in the organism with ischemia due to tourniquet use and subsequent reperfusion. Oxidative stress increases postoperative morbidity. Some Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) perform their anti-inflammatory effects in part by binding or inhibiting their formation of active oxygen radicals at the site of inflammation. In this study, we aimed to evaluate the effect of IV ibuprofen on ischemia-reperfusion injury (IRI) in patients undergoing total knee arthroplasty over oxidative stress parameters. The patients were randomly divided into two groups. Each patient’s protocol number, age, sex, body mass index (BMI), additional disease, drug use, tourniquet time, hemoglobin value, additional analgesic requirement and application, adverse reaction development on the first postoperative day were recorded in the research follow-up form. Both groups of patients; before anesthesia, 45 minutes after tourniquet application, 5 minutes after tourniquet lowering, 20 minutes after tourniquet lowering and at 24th-hour post-op; TOS, TAS, paraoxonase, arylesterase, myeloperoxidase, catalase, ceruloplasmin, albumin, IMA, thiol-disulfide balance tests were studied. Statistical analysis of test results was performed. We observed that antioxidants decreased and oxidants increased on the first postoperative day in both groups in patients who underwent total knee arthroplasty. The decrease in antioxidant parameters was higher in IV ibuprofen doses compared to the control group in the case group; these doses indicate that the drug adversely affects the organism in the fight against oxidative stress, which is an undesirable effect. To evaluate this negative effect of IV ibuprofen which is increasingly used in postoperative analgesia, studies with different doses of drugs and different surgeries may be needed.

Protective Effects of Rocuronium Bromide on Ischemia-Reperfusion Injury in Skeletal Muscle Induced by Tourniquet in Patients Undergoing Elective Unilateral Total Knee Arthroplasty: A Prospective, Double Blind, Randomized, Controlled Study.

PurposeTo investigate the effects of different doses of rocuronium on ischemia-reperfusion injury in skeletal muscle induced by tourniquet in patients undergoing elective unilateral total knee arthroplasty.Patients and MethodsA total of 90 patients undergoing elective unilateral knee arthroplasty under general anesthesia combined with femoral nerve block were randomly divided into 3 groups: normal saline group (group S), rocuronium 0.6 mg/kg group (group L), and rocuronium 1.2 mg/kg group (group H). The primary outcome was the expression of dystrophin in skeletal muscle at 60 min after ischemia. Secondary outcomes included the concentration of malondialdehyde (MDA) and neuronal nitric oxide synthase (nNOS) in blood at 5 min and 30 min after reperfusion. In addition, thigh girth at 24 h and 48 h after operation, the leaving bed time, the incidence of tourniquet-related hypertension and short-term (3 days after operation) complications (nausea and vomiting, swelling, blister, wound infection) and long-term (3 months after operation) complications (joint instability, stiffness, nerve paralysis, pain) were recorded.Main ResultsThe expression of dystrophin in the rocuronium group was higher than that in group S after ischemia (P <0.05). The concentration of MDA in the rocuronium 1.2 mg/kg group was lower at 30 min after reperfusion (P < 0.05). There was no significant difference in nNOS among groups at each time point (P > 0.05). The change of thigh girth was the smallest in the rocuronium 1.2 mg/kg group after operation (P<0.05). The leaving bed time was significantly earlier after operation in the rocuronium group than that in group S (P <0.05).ConclusionRocuronium can protect skeletal muscle from ischemia-reperfusion injury induced by tourniquet. The mechanism may be related to the fact that rocuronium can reduce the loss of dystrophin in skeletal muscle and have the effects of anti-oxidation and anti-stress.Trial RegistrationThe study was registered at http://www.chictr.org.cn (ChiCTR1800019221, registered on 2018–10-31).

Effects of different methods of using pneumatic tourniquet in patients undergoing total knee arthroplasty: a randomized control trial.

The goal of this work was to investigate the effects of different methods of using pneumatic tourniquet on reducing blood loss in patients undergoing cemented total knee arthroplasty (TKA). One hundred and fifty patients undergoing unilateral cemented TKA were randomly divided into three groups (50 patients per group). The tourniquet was used during the entire operation (Group A), used from the beginning of operation to the completion of joint replacement (Group B), and from the beginning of osteotomy to the completion of arthroplasty (Group C). The following parameters were recorded: intraoperative blood loss (IBL), postoperative blood loss (PBL), hidden blood loss (HBL), and total blood loss (TBL); operation time and tourniquet time; incidence of postoperative complications; and hospital for special surgery (HSS) score. IBL, HBL, and TBL in group C was significantly less than that in group B (all P<0.05). Tourniquet time in group C was significantly less than that in groups A and B (all P<0.05). The incidence of tourniquet-related complications in group C (6%) was relatively lower than that in group A (10%) during hospitalization (P>0.05). Post-operative HSS scores at 2weeks after the operation in group C was significantly higher than that in group A and group B (all P<0.05). Our results suggest that using a tourniquet from the beginning of osteotomy to the completion of arthroplasty could significantly reduce TBL in TKA, and decrease the incidence of complications; thereby facilitating early post-operative functional recovery.

The Effect of Different Regional Blocks: Combined Femoral-Sciatic, Spinal and Epidural Blocks on the Different Side Effects of Arterial Tourniquet in Patients Undergoing Lower Limb Orthopedic Surgeries —A Randomized Controlled Trail

Background: Pneumatic arterial tourniquet is a very commonly used technique in limb surgeries to provide bloodless field to facilitate dissection and decrease blood loss. However, arterial tourniquet has many deleterious effects including hemodynamic changes, serum lactate and potassium level changes and tourniquet-induced pain which sometimes can be severe and intolerable. Aim of the study: To evaluate the effect of different regional blocks: femoral-sciatic, spinal and epidural blocks on serum lactate and potassium levels and the degree of arterial tourniquet-induced pain in patients undergoing lower limb orthopedic surgeries. Methods: 60 patients underwent lower limb orthopedic surgery with application of tourniquet for duration not more than 90 minutes. Patients were assigned randomly to one of three groups (20 each) Group I had sciatic-femoral block, Group II: patients had spinal anesthesia and Group III: patients had epidural anesthesia. Intraoperative hemodynamics, changes in serum potassium and lactate levels and tourniquet pain after tourniquet inflation & deflation, were recorded. Results: There was no statistically significant difference among the three groups regarding tourniquet pain after tourniquet inflation (p = 0.872) and deflation (p = 0.902), and regarding serum levels changes of potassium (p = 0.067) and lactate (p = 0.051). However, each group showed statistically significant increase in post deflation tourniquet pain (p = 0.003, 0.002, 0.003, in groups F, S, E respectively) and serum potassium (p = 0.004, 0.006, 0.000, in groups F, S, E respectively) and lactate levels (p = 0.004, 0.000, 0.000, in groups F, S, E respectively) when compared to the pre-deflation values, and the increase was directly proportional to the duration of tourniquet. Conclusion: the three different types of anesthesia (femoral-sciatic, spinal and epidural block) have the same effect on serum lactate and potassium levels and the degree of tourniquet pain, which were related to the duration of tourniquet inflation.

Massive bleeding despite tourniquet inflation in total knee replacement patient with a femoro-popliteal artery bypass graft

Massive bleeding despite tourniquet inflation in total knee replacement patient with a femoro-popliteal artery bypass graft

The impact of tourniquet on patient satisfaction in carpal tunnel decompression

Abstract Release of the transverse carpal ligament can be performed safely under local anesthesia and without the use of tourniquet. There are conflicting reports for the use of tourniquet in carpal tunnel syndrome. The aim of the study was to compare the patient satisfaction with and without tourniquet in patients with carpal tunnel decompression. This was a retrospective study performed in twenty-four patients who underwent bilateral carpal tunnel decompression. All the patients were diagnosed using a combination of clinical history, clinical tests and EMG recordings. One side was operated with use of tourniquet and other side without. Patient evaluation measure was used to assess the satisfaction score. A telephonic interview was conducted and patients were asked the questions regarding discomfort caused by tourniquet. The results demonstrated that there was a significant difference in discomfort at the tourniquet site at the time of operation (p&lt;0.00017). Long term, there was no apparent difference in functional outcome of patients operated on with or without tourniquet. There was also no significant difference in subjective sensation, grip or use of hand in patients who underwent carpal tunnel release with or without tourniquet. We conclude that we should not use tourniquet in carpal tunnel decompression.

Comparison of mepivacaine and lidocaine for intravenous regional anaesthesia: pharmacokinetic study and clinical correlation

Limitations to the use of lidocaine for intravenous regional anaesthesia (IVRA) include lack of optimal intraoperative analgesia and systemic toxic reactions. This randomized double-blind study was conducted to compare intraoperative and postoperative analgesia, adverse effects, and plasma concentrations of mepivacaine or lidocaine, on release of the tourniquet in patients undergoing IVRA for distal upper limb surgery. Forty-two adult patients were randomly allocated to receive either a 0.5% lidocaine solution 3 mg kg(-1) (n=20) or mepivacaine 5 mg kg(-1) (n=22). Plasma concentrations of both anaesthetic agents were measured at 5, 10, 20, 30, 45, and 60 min after deflation of the tourniquet by gas chromatography. Although plasma concentrations of mepivacaine and lidocaine were comparable 5 min after deflation, concentrations of lidocaine decreased significantly thereafter, whereas plasma concentrations of mepivacaine were similar over the 60-min study period. Supplementary analgesia during the intraoperative period was required by 45% of patients in the lidocaine group as compared with 9% in the mepivacaine group (P=0.02). No adverse effects were observed in patients given mepivacaine. In the lidocaine group, adverse effects were observed in 10% of the patients. The total ischaemia time, volume of the local anaesthetic, and duration of the surgical procedure were not significantly different between the two groups. Mepivacaine 5 mg kg(-1) ensured better intraoperative analgesia than lidocaine 3 mg kg(-1) when used for IVRA. Plasma concentrations of lidocaine decreased significantly between 5 and 60 min following tourniquet deflation, whereas blood concentrations of mepivacaine remained below the toxic concentration.

Lack of pressure pain modulation by heterotopic noxious conditioning stimulation in patients with painful osteoarthritis before, but not following, surgical pain relief

To investigate the influence of chronic nociceptive pain on endogenous pain modulation, the effect of heterotopic noxious conditioning stimulation (HNCS) on perception of various somatosensory modalities was assessed in 15 patients with painful osteoarthritis of the hip. Thirteen patients were re-assessed when pain-free 6–14 months following surgery. Sex- and age matched healthy subjects assessed at similar time intervals served as controls. The effects of HNCS were tested using the upper extremity submaximal effort tourniquet test. Subjects rated tourniquet-induced pain intensity on a visual analogue scale (VAS). Quantitative sensory testing (QST) was performed contralaterally to the maximally painful area in 13 patients and contralaterally to the second most painful area in two patients (i.e. lateral thigh n=12, frontal thigh n=1, lateral calf n=2). Sensibility was assessed before, during and 45 min following the tourniquet test. Perception thresholds to light touch were assessed using von Frey filaments and pressure pain thresholds by pressure algometry. Perception thresholds to non-painful and painful warmth and cold were determined using a Thermotest. In both sessions, patients rated the tourniquet-induced pain higher than controls at the start ( P<0.003 and P<0.006, respectively), but not at the end of the tourniquet test. Decreased sensitivity to light touch ( P<0.001) and innocuous cold ( P<0.002) was seen during the tourniquet in patients and controls alike, on both occasions, while perception thresholds to innocuous warmth and heat pain remained unaffected. In the first session, pressure pain thresholds increased during the tourniquet test in controls ( P<0.002), but not in patients. In the second session, pressure pain thresholds increased during the tourniquet test in controls ( P<0.001) and in patients ( P<0.02). In conclusion, no pressure pain modulation was induced by HNCS in patients before surgery, as opposed to controls, suggesting a dysfunction in systems subserving ‘diffuse noxious inhibitory controls’ (DNIC). Normal pressure pain modulation induced by HNCS was seen when patients were re-assessed in a pain-free state following surgery, indicating that the dysfunction of DNIC had been maintained by chronic nociceptive pain.

Use of a Tourniquet in Patients with Sickle-Cell Disease

Fifteen patients, 13 male and two female, known to be carrying the sickle-cell gene (12 HbSS and 3 HbAS), who were undergoing operations requiring a bloodless field, were included in the study. Of the 12 with HbSS, seven had haemoglobin A1 component of between 11 and 27%, three had fetal haemoglobin ranging from 5.7 to 29% and the remaining two had increased haemoglobin A2 concentrations suggesting a beta non-thalassaemia combination. All had a tourniquet applied to the appropriate limb and were given general anaesthesia with moderate hyperventilation throughout the procedure. The tourniquet inflation time was 61.7 +/- 27.5 min. The mean PaO2 remained above 200 mmHg, mean PaCO2 was less than 37 mmHg, and pH ranged between 7.40 and 7.45. There were no clinically important changes in BP or ECG. All patients made uneventful recoveries and none developed sickle-cell crises. It is suggested that it is safe to use tourniquet in patients with sickle-cell disease provided optimum acid-base status and oxygenation are maintained throughout the procedure.

Use of a tourniquet in patients with sickle-cell disease.

Fifteen patients, 13 male and two female, known to be carrying the sickle-cell gene (12 HbSS and 3 HbAS), who were undergoing operations requiring a bloodless field, were included in the study. Of the 12 with HbSS, seven had haemoglobin A1 component of between 11 and 27%, three had fetal haemoglobin ranging from 5.7 to 29% and the remaining two had increased haemoglobin A2 concentrations suggesting a beta non-thalassaemia combination. All had a tourniquet applied to the appropriate limb and were given general anaesthesia with moderate hyperventilation throughout the procedure. The tourniquet inflation time was 61.7 +/- 27.5 min. The mean PaO2 remained above 200 mmHg, mean PaCO2 was less than 37 mmHg, and pH ranged between 7.40 and 7.45. There were no clinically important changes in BP or ECG. All patients made uneventful recoveries and none developed sickle-cell crises. It is suggested that it is safe to use tourniquet in patients with sickle-cell disease provided optimum acid-base status and oxygenation are maintained throughout the procedure.

Changes of the spinal evoked potential induced by lateral compression of the spinal cord in dogs

To investigate the influence of chronic nociceptive pain on endogenous pain modulation, the effect of heterotopic noxious conditioning stimulation (HNCS) on perception of various somatosensory modalities was assessed in 15 patients with painful osteoarthritis of the hip. Thirteen patients were re-assessed when pain-free 6–14 months following surgery. Sex- and age matched healthy subjects assessed at similar time intervals served as controls. The effects of HNCS were tested using the upper extremity submaximal effort tourniquet test. Subjects rated tourniquet-induced pain intensity on a visual analogue scale (VAS). Quantitative sensory testing (QST) was performed contralaterally to the maximally painful area in 13 patients and contralaterally to the second most painful area in two patients (i.e. lateral thigh n=12, frontal thigh n=1, lateral calf n=2). Sensibility was assessed before, during and 45 min following the tourniquet test. Perception thresholds to light touch were assessed using von Frey filaments and pressure pain thresholds by pressure algometry. Perception thresholds to non-painful and painful warmth and cold were determined using a Thermotest. In both sessions, patients rated the tourniquet-induced pain higher than controls at the start (P<0.003 and P<0.006, respectively), but not at the end of the tourniquet test. Decreased sensitivity to light touch (P<0.001) and innocuous cold (P<0.002) was seen during the tourniquet in patients and controls alike, on both occasions, while perception thresholds to innocuous warmth and heat pain remained unaffected. In the first session, pressure pain thresholds increased during the tourniquet test in controls (P<0.002), but not in patients. In the second session, pressure pain thresholds increased during the tourniquet test in controls (P<0.001) and in patients (P<0.02). In conclusion, no pressure pain modulation was induced by HNCS in patients before surgery, as opposed to controls, suggesting a dysfunction in systems subserving ‘diffuse noxious inhibitory controls’ (DNIC). Normal pressure pain modulation induced by HNCS was seen when patients were re-assessed in a pain-free state following surgery, indicating that the dysfunction of DNIC had been maintained by chronic nociceptive pain.

Use of the Tourniquet During Surgery in Patients with Sickle Cell Hemoglobinopathies

Twenty-one patients carrying the sickle cell gene underwent 29 operative procedures using tourniquet-induced ischemia. No statistically increased incidence of complications occurred in the sickle cell group when compared with a control group of black patients who did not have the sickle cell trait, but who underwent similar operative procedures. There was no obvious contraindication to the use of the tourniquet in patients carrying the sickle cell gene.