The hemodynamic and metabolic effects of tourniquet application during knee surgery

We evaluated the effects of tourniquet application on the cardiovascular system and metabolism in 10 young men undergoing knee surgery with general anesthesia. The duration of inflation was from 75 to 108 min. Heart rate, mean arterial pressure, cardiac index (CI) by pulse contour method, and systemic vascular resistance were measured before, during, and after tourniquet inflation. pH, PaO(2), PaCO(2), and lactate blood concentrations were also measured. VO(2) and VCO(2) were assessed every minute from tracheal intubation up to 15 min after tourniquet deflation and VO(2) in excess of the basal value over the 15 min after deflation (VO(2)exc) was calculated. Mean arterial pressure increased 26% (P: < 0.05) during inflation and returned to basal values after deflation. CI did not change immediately after inflation; although, thereafter, it increased 18% (P: < 0.05). Five minutes after deflation, CI further increased to a value 40% higher than the basal value. Therefore, systemic vascular resistance increased 20% suddenly after inflation (P: < 0.05) and decreased 18% after deflation (P: < 0.05). VO(2) and VCO(2) remained stable during inflation and increased (P: < 0.05) after deflation. VO(2)exc depended on duration of tourniquet inflation time (Tisch) (P: < 0.05). After deflation, PaCO(2) and lactate increased (P: < 0.05) while Tisch increased. We conclude that tourniquet application induces modifications of the cardiovascular system and metabolism, which depend on tourniquet phase and on Tisch. Whether these modifications could be relevant in patients with poor physical conditions is not known. Implications: The clinical effects of tourniquet application were evaluated in 10 young men undergoing knee surgery. Our data indicate that tourniquet application causes hemodynamic and metabolic changes which may become clinically relevant after a long period of tourniquet inflation, particularly in patients with concomitant cardiovascular diseases.     

The hemodynamic and metabolic changes following tourniquet release during halothane anesthesia

We measured the hemodynamic and metabolic changes following the release of lower limb tourniquet during halothane anesthesia, and discussed the cause of reduction in the blood pressure and the effective method for prevention. Cardiac index decreased transiently following the release, and gradually increased afterward. Systemic vascular resistance index decreased continuously and progressively until 10 minutes after the release. These results indicate that the causative factors of reduction in the blood pressure are temporary decrease in cardiac output and subsequent decrease in systemic vascular resistance. In mixed venous blood, pH decreased, PCO2 increased and HCO3- remained unchanged after the release. It seems that pH reduction was chiefly caused by the increase in PO2. Thus, the preventive method for reduction in the blood pressure following the tourniquet release may be as follows; 1) intravenous fluid loading, 2) hyperventilation, 3) elevation of lower limb, 4) lightning the anesthesia, and 5) finally giving vasopressors.     

右美托咪啶抑制术中止血带所致心血管反应的临床研究

目的：探讨右美托咪啶对全麻下外科手术中肢体应用止血带辅助止血所致心血管反应的抑制作用.方法：38例患者全麻下行下肢骨科手术,随机分为右美托咪定组（DEX组,n=19）和对照组（n=19）.DEX组麻醉开始前静脉输注负荷剂量右美托咪啶1 μg/kg,10 min输注完毕后以0.5 μg·kg-1·h-1持续输至术毕;对照组以相同方法输注等量生理盐水.负荷剂量输完后两组采用相同的麻醉诱导和维持方法.于患者入手术室后（T0）,止血带充气前（T1）,充气后10 min（T2）、20 min（T3）、30 min（T4）、40 min（T5）、50 min（T6）、60 min（T7）,松开止血带后5min（T8）、10 min（T9）,记录有创收缩压（ISBP）、有创舒张压（IDBP）、心率、脑电双频谱指数（BIS）值,并记录停药至自主呼吸恢复及拔管所用时间.结果：与T0比较,T1时两组血压、心率、BIS值都明显降低（P〈0.05）,但两组间比较差异无显著性（P〉0.05）;与T1比较,对照组T3～T8时ISBP、IDBP、心率增高,T7达到峰值（P〈0.05或〈0.01）,DEX 组T1～T9时无显著变化（P〉0.05）.与DEX组比较,对照组T3～T8时ISBP、IDBP升高,T4～T9时心率增快（P〈0.05或〈0.01）.两组自主呼吸恢复时间、拔管时间差异均无显著性（P〉0.05）.结论：右美托咪啶可有效抑制全麻下应用肢体止血带所致的心血管反应,对患者苏醒时间无影响.     

Effect of tourniquet time on postoperative quadriceps function

Postoperative weakness of quadriceps function following knee arthrotomy has often been attributed to pain inhibition or lack of motivation. However, the delayed recovery may be the result of a slowly resolving axonal compression syndrome caused by the pneumatic tourniquet. Forty-eight patients who underwent knee arthrotomy were evaluated including postoperative electromyographic testing and clinical follow-up. Thirty of these patients (62.5%) developed postoperative EMG changes. Abnormalities were noted in various muscle groups but most commonly involved the quadriceps alone or quadriceps and gastrocnemius. An effort was made in 20 patients to substantially decrease the duration of tourniquet compression by limiting tourniquet inflation to intracapsular portions of the procedures. Fewer EMG changes and more rapid clinical recovery were noted in patients with decreased tourniquet times, suggesting that it is beneficial to minimize the duration of tourniquet compression. In all patients who returned for serial testing, the EMG abnormalities eventually resolved.     

Effect of high-dose of methylprednisolone on tourniquet ischaemia

High doses of corticosteroids have been found to have beneficial effects in various shock states. It has been well recognized that ischaemia is one of the important features in shock states. This prompted us to investigate the effect of high-dose methylprednisolone on tourniquet-induced ischaemia using mongrel dogs. After inflation of tourniquets to 600 mmHg on each thigh of the hind legs, one leg received an intravenous infusion of methyl-prednisolone, 3 mg.kg-1 dissolved in 20 ml of autologous blood. The other leg received the same amount of blood only, as a control. During two hours of tourniquet time and until 30 min after tourniquet deflation, venous blood was sampled five times from both hind legs for measurements of blood gas tensions (PvO2, PvCO2) and pH, lactic acid, creatinine kinase (CK), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH). During tourniquet ischaemia, PvO2 and pH dropped and PvCO2, lactic acid, CK, AST and LDH rose steadily and significantly in both groups of legs, indicating respiratory and metabolic acidosis, and muscle cell damage. However, those changes were significantly smaller in the methylprednisolone-treated legs. The beneficial effect of methylprednisolone could be attributed to its vasodilatory effect, cellular membrane stabilization and direct metabolic effect on skeletal muscle cells. Although the tourniquet-induced ischaemia in our study is slightly different from the clinical paradigm, the results suggest that high-dose methylprednisolone may provide a beneficial effect during tourniquet ischaemia.     

Isolated limb perfusion: distinct tourniquet and tumor necrosis factor effects on the early hemodynamic response

HYPOTHESIS: Recent evidence indicates that tumor response rates after isolated limb perfusion (ILP) are improved when tumor necrosis factor (TNF) is added to the locoregional perfusion of high doses of chemotherapy. Other factors, related to the patient or the ILP procedure, may interfere with the specific role of TNF in the early hemodynamic response after ILP with TNF and high-dose chemotherapy. DESIGN: Case-control study. SETTING: Tertiary care university hospital. PATIENTS: Thirty-eight patients with a locoregionally advanced tumor of a limb treated by ILP with TNF and high-dose chemotherapy (TNF group) were compared with 31 similar patients treated by ILP with high-dose chemotherapy alone (non-TNF group). INTERVENTIONS: Swan-Ganz catheter hemodynamic recordings, patients' treatment data collection, and TNF and interleukin 6 plasma level measurements at regular intervals during the first 36 hours following ILP. MAIN OUTCOME MEASURES: Hemodynamic profile and total fluid and catecholamine administration. RESULTS: In the TNF group, significant changes were observed (P<.006): the mean arterial pressure and the systemic vascular resistance index decreased, and the temperature, heart rate, and cardiac index increased. These hemodynamic alterations started when the ILP tourniquet was released (ie, when or shortly after the systemic TNF levels were the highest). The minimal mean arterial pressure, the minimal systemic vascular resistance index, the maximal cardiac index, the intensive care unit stay, and the interleukin 6 maximal systemic levels were significantly (P<.001 for all) correlated to the log(10) of the systemic TNF level. In the non-TNF group, only a brief decrease in the blood pressure following tourniquet release and an increase in the temperature and in the heart rate were statistically significant (P<.006). Despite significantly more fluid and catecholamine administration in the TNF group, the mean arterial pressure and the systemic vascular resistance index were significantly (P<.001) lower than in the non-TNF group. CONCLUSIONS: Release of the tourniquet induces a blood pressure decrease that lasts less than 1 hour in the absence of TNF and that is distinct from the septic shock-like hemodynamic profile following TNF administration. The systemic TNF levels are correlated to this hemodynamic response, which can be observed even at low TNF levels.     

Effect of gabapentin pretreatment on propofol consumption,hemodynamic variables,and postoperative pain relief in breast cancer surgery

Study objectiveGabapentin is an inhibitory neurotransmitter of the central nervous system. This prospective randomized double-blind study was conducted to evaluate the effects of gabapentin on intraoperative propofol requirements, hemodynamic variables, and postoperative pain relief in breast cancer patients.Materials and methodsForty adult females of the American Society of Anesthesiologists (ASA) Grade I-II physical status, undergoing total mastectomy for breast cancer were included. Patients were randomly allocated into two groups. Two hours prior to surgery the gabapentin group received gabapentin 600 mg and the control group received placebo. Anesthesia was induced with intravenous fentanyl, propofol, and vecuronium, and maintained with propofol infusion titrated according to the bispectral index. Postoperative analgesia was provided with intramuscular diclofenac sodium and intravenous morphine on demand.ResultsThe intraoperative propofol consumption was significantly less in the gabapentin group as compared with the control group (p = 0.009), whereas there was no difference in fentanyl and vecuronium requirements. Patients in the gabapentin group had lower pain scores at 30 minutes, 1 hour, and 2 hours postoperatively (p < 0.001). The postoperative morphine consumption was also less in the gabapentin group compared with the control group (p = 0.006). No significant adverse effects were noticeable.ConclusionPreoperative administration of gabapentin reduced intraoperative propofol requirements and postoperative analgesic consumption in breast cancer patients undergoing total mastectomy.     

The effects of experimental venous carbon dioxide embolization on hemodynamic and respiratory variables

BACKGROUND: Laparoscopic liver resection is a relatively new surgical procedure. Carbon dioxide (CO2) pneumoperitoneum and laparoscopic liver dissection are recognized as risk factors for CO2 embolism to the pulmonary circulation. The embolization can be difficult to detect and can theoretically increase peri-operative morbidity. The aim of this study was to evaluate the cardiopulmonary effects in a pig model during a time period of 4 h after an experimental CO2 embolization. METHODS: Eleven piglets were anesthesized. Nine were embolized with a single intravenous injection of 0.4 ml/kg CO2 and two served as controls. Respiratory and cardiovascular variables, including pulmonary artery pressure and cardiac output, were monitored for 4 h after embolization, and arterial blood gases were monitored on-line. RESULTS: The embolized piglets had an increase in ventilatory dead space, pulmonary vascular resistance and pulmonary artery pressure and a decrease in cardiac output that lasted throughout the 4-h observation time. The mean arterial pressure and heart rate were unchanged. An early sign of embolization was a rapid fall in end-tidal CO2 and P(a)O2 and a rise in P(a)CO2. CONCLUSION: Negative changes in cardiopulmonary physiology persisted for at least 4 h after a single intravenous CO2 injection, in spite of this gas being highly soluble in blood. This is a more prolonged influence of CO2 embolization than previously described. Extensive monitoring for early detection of an embolization may be recommended to limit morbidity in patients undergoing laparoscopic liver surgery.     

止血带对全膝关节置换术后深静脉血栓形成的影响

目的 探讨止血带对全膝关节置换术后深静脉血栓形成的影响.方法 采用随机对照研究,将连续入院的拟行初次全膝关节置换的80例患者随机分为两组:一组使用止血带(止血带组,40例),一组不使用止血带(非止血带组,40例).全部采用后十字韧带替代型骨水泥固定人工膝关节(Smith-Nephew),手术由同一组医生完成.比较两组患者围手术期失血量、深静脉血栓和肺动脉栓塞发生率、术中栓子面积百分率%Ae(即总栓子面积占右心房面积的百分率).术前及术后第1～10天行彩色多普勒超声检查,观察双下肢深静脉血栓的发生;术中使用经食道超声心动图监测右心房,评估止血带释放后的%Ae.结果 止血带组患者术中失血最小于非止血带组患者,但两组患者围手术期总失血量比较差异无统计学意义.止血带组患者和非止血带组患者深静脉血栓发生率比较无统计学差异,两组均未发生肺动脉栓塞.止血带组患者%Ae在释放止血带后的1 min达到高峰;非止血带组患者%Ae仅在扩髓和植入假体时出现高峰,然后缓慢下降;止血带组患者%Ae在释放止血带后大于非止血带组患者.结论 止血带的使用对全膝关节置换术围手术期总失血量并无明显影响,不增加深静脉血栓和肺栓塞的发生风险.     

Cardiac surgery patients present considerable variation in pre-operative hemodynamic variables

Background: It is essential to control hemodynamics in cardiac surgery. Patients are often monitored extensively in order to optimize hemodynamic performance. However, pre-operative values are normally unknown. Furthermore, hemodynamic goals may seem arbitrary and the lack of an evidence-based consensus may lead to both under- and over-treatment. The aim of this study was to evaluate the variables most commonly used for hemodynamic guidance in the post-operative period.
Methods: Ten patients scheduled for elective cardiac surgery were followed with invasive hemodynamic monitoring the night before surgery. All data were recorded automatically and electronically.
Results: We found considerable inter-patient differences and intra-patient variation. The greatest intra-patient variation was found in the cardiac index (CI), ranging from 1.9 to 5.3 l/min/m². Four patients had periodic CI <2.4 l/min/m². Eight patients showed SpO₂ values ≤92, four of them in more than 15% of the observations. Six patients had an SvO₂ <70% in more than 40% of the observations and two an SvO₂<64% in more than 20% of the observations.
Conclusions: This study is unique because hemodynamic reference data in cardiac surgery patients have not been published previously. The intra-patient variations were unexpectedly high in most hemodynamic variables and demonstrate the difficulties of using hemodynamic parameters as a guidance for treatment and indicate that goal-oriented therapy using currently accepted values may result in over-treatment in some patients.     

The effect of intravenous quinaprilat on plasma cytokines and hemodynamic variables during cardiac surgery

OBJECTIVES: Perioperative treatment with angiotensin-converting enzyme (ACE) inhibitors in cardiac surgery with cardiopulmonary bypass is still controversial. Using ACE inhibitors during cardiac surgery might be associated with an increased risk of critical hypotensive episodes. On the other hand, ACE inhibitors could have beneficial effects with respect to the development of the systemic inflammatory response syndrome. DESIGN: The effect of acute administration of quinaprilat on hemodynamic variables and plasma cytokines was assessed under double-blind, randomized, and placebo-controlled conditions. SETTING: Department of anesthesiology and cardiovascular surgery clinic in a university hospital. PARTICIPANTS: Forty patients without preexisting cardiac failure, undergoing coronary artery bypass grafting. INTERVENTIONS: Patients received 0.08 mg/kg of intravenous quinaprilat or intravenous isotonic saline solution after induction of anesthesia. MEASUREMENTS AND RESULTS: Blood samples were taken after induction of anesthesia (T0), before cardiopulmonary bypass (T1), at the end of surgery (T2), and 4 hours after the end of surgery (T3). There was no difference between the 2 groups regarding mean arterial pressure and inotropic or vasopressor support. Systemic vascular resistance index was significantly lower in the quinaprilat group at T2 (p = 0.016) and T3 (p = 0.017). No difference in proinflammatory cytokine levels was observed between the 2 groups. CONCLUSIONS: The present investigation shows that acute administration of an intravenous ACE inhibitor, quinaprilat, has no influence on proinflammatory cytokines during cardiac surgery with cardiopulmonary bypass. The patients treated with quinaprilat showed an improved systemic vascular resistance index with no increased risk of deleterious hemodynamic episodes.     

Effect of tourniquet ischaemia on carbohydrate metabolism of dog skeletal muscle

Metabolic changes in blood and skeletal muscle of dogs before, during and after tourniquet ischaemia were investigated to obtain further information on cellular metabolic abnormalities and restitution during and following long-lasting blood flow interruptions. Total carbohydrate and glycogen contents in the muscle tissue fell during ischaemia and remained significantly decreased even 1 h after recirculation due to inhibition of glycogen synthetase activity. Muscle glucose concentration remained stable during ischaemia and was significantly elevated 1 h after tourniquet release. In contrast, muscle lactate concentration was elevated during ischaemia and normal after recirculation. Blood lactate, pyruvate and serum inorganic phosphate concentrations increased markedly after tourniquet release and were still significantly elevated 1 h after recirculation, whereas ketone bodies and citric acid cycle intermediates remained unchanged. Tourniquet ischaemia had no effect on muscle phosphate concentration or on the activities of proteases, protease inhibitors or hydrolases in the blood. Nevertheless, our results clearly indicate metabolic abnormalities in the blood and skeletal muscle during 5 h of tourniquet ischaemia and even after 1 h of recirculation.     

Effect of clonidine on upper extremity tourniquet pain in healthy volunteers

BACKGROUND AND OBJECTIVES: Tourniquet pain is often a limiting factor during intravenous regional anesthesia (IVRA). The purpose of this study was to evaluate the efficacy of 1 microg/kg of clonidine added to IVRA-lidocaine in decreasing the onset of severe tourniquet pain. METHODS: Upper extremity IVRA was performed in 15 volunteers with a double-cuffed tourniquet on 2 separate occasions at least 1 week apart. IVRA was established with either 40 mL 0.5% lidocaine (IVRA-L) or 40 mL 0.5% lidocaine with 1 microg/kg clonidine (IVRA-Cl). Verbal pain scores (VPS) from 0 to 10 were recorded every 5 minutes. When the VPS reached 6, the distal cuff was inflated, and the proximal cuff was deflated. This was defined as the first tourniquet time (T1). The study was terminated at a VPS of 10, or at 60 minutes, whichever occurred first. The time from distal cuff inflation to deflation was defined as the second tourniquet time (T2). Total tourniquet time (TT) was the sum of T1 and T2. RESULTS: T1 for IVRA-L (21.6 +/- 3.9) and IVRA-Cl (22.7 +/- 2.7) were not significantly different. T2 and TT were significantly longer (P < .0001; P < .0007, respectively) for IVRA-Cl (33.0 +/- 6.2; 55.6 +/- 6.6) than for IVRA-L (25.5 +/- 4.4; 47.1 +/- 5.2). CONCLUSION: This study shows that the addition of 1 microg/kg of clonidine to 40 mL of 0.5% IVRA-L delays the onset time of tourniquet pain in healthy, unsedated volunteers.     

Influence of crystalloid and colloid replacement solutions on hemodynamic variables during acute normovolemic hemodilution

STUDY OBJECTIVE: To determine whether, in maintaining normovolemia during acute normovolemic hemodilution, replacement fluid choice influences intraoperative hemodynamic variables. DESIGN: Prospective, randomized, single-blinded study. SETTING: Operating room of a tertiary-care university hospital. PATIENTS: 40 adult, ASA physical status I, II, and III patients scheduled for acute normovolemic hemodilution during radical prostatectomy. INTERVENTIONS: Patients were randomly assigned to four replacement fluid groups to receive 1) Ringer's lactate, 2) 5% albumin, 3) 6% dextran 70, or 4) 6% hetastarch. A standardized general anesthetic was used, and patients underwent moderate hemodilution to a target hemoglobin of 9 gm/dL. MEASUREMENTS: Hemodynamic variables were recorded using standard monitors, 5-lead electrocardiography, radial arterial catheter, and pulmonary artery catheter. Red blood cell loss for the entire hospitalization was calculated. MAIN RESULTS: Demographic and clinical outcome data were similar among the groups. During acute normovolemic hemodilution, heart rate and pulmonary capillary wedge pressure were unchanged from baseline in all groups, but patients receiving Ringer's lactate or albumin had greater declines in mean arterial pressure at the end of acute normovolemic hemodilution. Cardiac and oxygen consumption indexes were stable during acute normovolemic hemodilution, but oxygen extraction increased. CONCLUSIONS: During hemodilution, anesthetized patients maintain whole body oxygenation by increasing oxygen extraction. The administration of hetastarch or dextran as the replacement fluid during acute normovolemic hemodilution is associated with a more stable mean arterial pressure, but overall acute normovolemic hemodilution is well tolerated irrespective of the replacement fluid used.     

The effects of transesophageal echocardiography on hemodynamic variables in small infants undergoing cardiac surgery

OBJECTIVE: To assess the effects of transesophageal echocardiography (TEE) on hemodynamic variables during cardiac surgery in small infants. DESIGN: A prospective clinical study. SETTING: A medical college-affiliated tertiary care children's hospital. PARTICIPANTS: Twenty-three infants weighing 2 to 5 kg undergoing cardiac surgery. INTERVENTIONS: Baseline heart rate, arterial pressure, and central venous pressure were recorded. A pediatric TEE probe was inserted, and the hemodynamic variables were again recorded. Postoperatively the hemodynamic measurements were measured again before and after probe removal, with the addition of left atrial pressure and pulmonary artery pressure when available. Hemodynamic parameters were carefully observed during all phases of the TEE examinations for any changes attributable to probe manipulation. MEASUREMENTS AND MAIN RESULTS: No statistically significant changes occurred in this group of patients during TEE. No clinically significant changes in any individual patient occurred during the measurement or during manipulation of the TEE probe for the complete examination. CONCLUSION: Although hemodynamic compromise can occur in small infants, this study suggests that it is infrequent. Fear of hemodynamic compromise should not prevent use of intraoperative TEE in small infants when otherwise indicated.     

止血带对全膝关节置换术后深静脉血栓形成的影响

目的 探讨止血带对全膝关节置换术后深静脉血栓形成的影响.方法 采用随机对照研究,将连续入院的拟行初次全膝关节置换的80例患者随机分为两组:一组使用止血带(止血带组,40例),一组不使用止血带(非止血带组,40例).全部采用后十字韧带替代型骨水泥固定人工膝关节(Smith-Nephew),手术由同一组医生完成.比较两组患者围手术期失血量、深静脉血栓和肺动脉栓塞发生率、术中栓子面积百分率%Ae(即总栓子面积占右心房面积的百分率).术前及术后第1～10天行彩色多普勒超声检查,观察双下肢深静脉血栓的发生;术中使用经食道超声心动图监测右心房,评估止血带释放后的%Ae.结果 止血带组患者术中失血最小于非止血带组患者,但两组患者围手术期总失血量比较差异无统计学意义.止血带组患者和非止血带组患者深静脉血栓发生率比较无统计学差异,两组均未发生肺动脉栓塞.止血带组患者%Ae在释放止血带后的1 min达到高峰;非止血带组患者%Ae仅在扩髓和植入假体时出现高峰,然后缓慢下降;止血带组患者%Ae在释放止血带后大于非止血带组患者.结论 止血带的使用对全膝关节置换术围手术期总失血量并无明显影响,不增加深静脉血栓和肺栓塞的发生风险.     

Effect of tourniquet use on blood loss in total knee arthroplasty

AIM: To reduce blood loss in total knee arthroplasty various physical measures including the use of a tourniquet are recommended. The question of an early tourniquet release is still unsettled. PATIENTS AND METHOD: To confirm our theory that blood loss and need of blood transfusions might be reduced while removing the tourniquet for meticulous hemostasis before wound closure we analysed 70 (41 male, 29 female) consecutive patients with total knee arthroplasty for osteoarthritis performed by a single surgeon in a prospective-randomized study between 1/1996 to 6/1998. In group I the tourniquet was released before, in group II after wound closure. RESULTS: We couldn't find any significant differences in the estimated blood loss, the decrease of hemoglobin and hematocrit level, and the transfusion need. In Group II we observed two cases of deep vein thrombosis. This difference was not significant. CONCLUSION: We conclude that tourniquet release for hemostasis is not an effective tool in reducing blood loss or transfusion need in total knee arthroplasty.