Tourniquet release: systemic and metabolic effects

Implementing Tourniquet Conversion Guidelines for Civilian EMS and Prehospital Organizations : A Case Report and Review

Since the first documented use of a tourniquet in 1674, the popularity of tourniquets has waxed and waned. During recent wars and more recently in Emergency Medical Services systems, the tourniquet has been proven to be a valuable tool in the treatment of life-threatening hemorrhage. However, tourniquet use is not without risk, and several studies have demonstrated adverse events and morbidity associated with tourniquet use in the prehospital setting, particularly when left in place for more than 2 h. Consequently, the US military's Committee on Tactical Combat Casualty Care has recommended guidelines for prehospital tourniquet conversion to reduce the risk of adverse events associated with tourniquets once the initial hemorrhage has been controlled. Emergency Medical Services systems that operate in rural, frontier, and austere environments, especially those with transport times to definitive care that routinely exceed 2 h, may consider implementing similar tourniquet conversion guidelines.

Cardiovascular Effects of Tourniquet Application with Cardiac Cycle Efficiency: A Prospective Observational Study

Objectives: The impact of the tourniquet on cardiac efficiency remains unknown. This study aimed to assess the impact of the tourniquet on cardiac cycle efficiency (CCE) and to interpret how general anesthesia (GA) or combined spinal epidural anesthesia (CSEA) affects this during surgery using cardiac energy parameters. Methods: This prospective observational study included 43 patients undergoing elective unilateral total knee arthroplasty (TKA) with a tourniquet divided into GA (n = 22) and CSEA (n = 21) groups. Cardiac energy parameters were measured before anesthesia (T1), pre-tourniquet inflation (T2), during inflation (T3-T8), and post-deflation (T9). The estimated power of the study was 0.99 based on the differences and standard deviations in CCE at T2-T3 for all patients (effect size: 0.88, alpha error: 0.05). Results: CCE decreased significantly more at T3 in the GA group than in the CSEA group, whereas dP/dtmax and Ea increased more (p < 0.05, p < 0.001, and p < 0.01, respectively). At T9, CCE increased significantly in the GA group, whereas dP/dtmax and Ea decreased (p < 0.05, p < 0.001, and p < 0.001, respectively). Conclusions: The tourniquet reduces cardiac efficiency through compensatory responses, and CSEA may mitigate this effect.

Change in the optic nerve sheath diameter after deflation of a pneumatic tourniquet: a prospective observational study

Applying a pneumatic tourniquet provides surgeons with a bloodless surgical field. However, application of the tourniquet induces various physiological changes. We evaluated the effect of tourniquet deflation on the intracranial pressure by using ultrasonography to measure the optic nerve sheath diameter (ONSD) in patients undergoing lower limb surgery. The ONSD was measured in 20 patients at five time points: after anesthetic induction (T0) and immediately before (T1), immediately after (T2), 5 min after (T3), and 10 min after tourniquet deflation (T4). Hemodynamic and respiratory variables were recorded. The ONSD showed significant differences at each point (P < 0.001). The ONSDs at T2 and T3 were significantly greater than that at T1 (P = 0.0007 and < 0.0001, respectively). The change in the end-tidal carbon dioxide partial pressure (EtCO2) was similar to the change in the ONSD. The change in the ONSD was significantly correlated with the change in the EtCO2 after tourniquet deflation (r = 0.484, P = 0.030). In conclusion, the ONSD, as an indicator of intracranial pressure, increased after tourniquet deflation in patients undergoing lower limb surgery. This was correlated with an increased EtCO2 and arterial carbon dioxide partial pressure.

Trial registration: ClinicalTrials.gov (NCT03782077).

Local infiltration analgesia for total knee arthroplasty: Does a mixture of ropivacaine and epinephrine have an impact on hemodynamics? An observational cohort study

Purpose:

High doses of local anesthetic administered intra-articularly and peri-articularly during local infiltration analgesia (LIA) for total knee arthroplasty (TKA) may have potential effects on patient hemodynamics. The aim of this study was to know if hemodynamic changes are associated with LIA in patients undergoing TKA.

Methods:

In a prospective observational design, elective patients undergoing orthopedic surgery for TKA and treated with LIA consisting of a mixture of ropivacaine (300 mg) and epinephrine (1 mg) were investigated for changes in selected hemodynamic parameters: heart rate (HR), non-invasively registered mean arterial blood pressure (MAP), and incidence of arrhythmias during the perioperative course, consisting of the following periods: period 1. from establishment of spinal anesthesia to prior to LIA administration, period 2. from administration of LIA to before release of ischemia tourniquet, period 3. from release ischemia tourniquet to end of surgery, and period 4. from transfer to the post anesthesia care unit to the ward. Statistical analysis was done with ANOVA-RM for the difference in means in repeated measurements, and with the Tukey Test between pairs. Data are presented as mean ± standard deviation. A P value <0.05 was considered significant.

Results:

Ninety-nine patients (mean age 77 ± 8 years) were included. HR increased from period 2 to period 3 up to 16% (67 ± 14 to 77 ± 13 bpm, P < 0.001), and from period 2 to period 4 up to 21% (67 ± 14 to 81 ± 12 bpm, P < 0.001). MAP showed no significant changes from period 2 to period 3 (89 ± 13 to 87 ± 13 mmHg, P > 0.50), and from period 2 to period 4 (89 ± 13 to 91 ± 11 mmHg, P > 0.50). No arrhythmias were detected during follow-up.

Conclusions:

A mixture of ropivacaine and epinephrine for LIA, despite the high doses administered, does not have a negative impact on hemodynamics.

The Hemodynamic Effect of Epinephrine-Containing Local Infiltration Analgesia After Tourniquet Deflation During Total Knee Arthroplasty: A Retrospective Observational Study

BACKGROUND

Local infiltration analgesia (LIA) is widely used in patients undergoing total knee arthroplasty and often contains epinephrine for a prolonged analgesic effect and to reduce systemic absorption of the local anesthetic. This retrospective observational study investigated the hemodynamic effect of locally infiltrated epinephrine after deflation of the tourniquet during total knee arthroplasty.

METHODS

We reviewed the electronic medical records of patients who underwent total knee arthroplasty between January 2017 and February 2018 at a tertiary care university hospital. Total knee arthroplasty was performed using a conventional technique with a pneumatic tourniquet. LIA consisted of ropivacaine, morphine sulfate, ketorolac, and methylprednisolone. The patients were grouped according to whether or not epinephrine was included in the LIA. The incidence of a hypertensive response (systolic blood pressure >160 mmHg or mean blood pressure >110 mmHg) after deflation of the tourniquet was compared between the 2 groups.

RESULTS

A total of 452 patients had received LIA with (n = 188) or without (n = 264) epinephrine. A hypertensive response after deflation of the tourniquet was more common in patients who received LIA containing epinephrine (42/188 [22.3%]) than in those who received LIA without epinephrine (14/264 [5.3%], P < .001). However, the incidence of hypotension after deflation of the tourniquet was not significantly different between the 2 groups (P = .976).

CONCLUSION

Because epinephrine-containing LIA can result in a hypertensive response after deflation of the tourniquet during total knee arthroplasty, it should be cautiously administered, especially in patients with cardiovascular comorbidities.

Reducing the Hypertensive Effects of the Prolonged Surgical Tourniquet Using a Dual-Cuff Strategy: A Prospective Randomized Controlled Trial

We evaluated whether moving the "line of crush" from thigh to the calf before onset of tourniquet-mediated hypertension would prevent or diminish it. We also evaluated any change in pain or functional outcome. Twenty adult patients were recruited and randomly assigned to either control or intervention groups. Inclusion criteria: any willing participant >18 years old with foot and/or ankle pathology requiring an operation lasting >90 minutes. Exclusion criteria included contraindication to general anesthesia, peripheral neuropathy affecting lower limbs of any etiology, or chronic pain requiring regular opiate analgesia. The intervention group received a thigh tourniquet for 60 minutes, after which a calf tourniquet was inflated and the thigh tourniquet was deflated. The control group received only a thigh tourniquet throughout surgery. At 90 minutes, the control group had mean arterial pressure of 86.8 mmHg, compared with the intervention group at 76.3 mmHg (p ≤ .014). At end of surgery, the difference had increased further (control 98.1 mmHg, intervention 78.3 mmHg (p ≤ .001). Moving the line of crush during limb tourniquet application prevents development of the hypertensive response. For cases in which a prolonged tourniquet application is required, a dual-tourniquet technique will prevent intraoperative hypertension and may influence long-term pain and function.

A randomized controlled trial to assess the effect of a ketamine infusion on tourniquet hypertension during general anaesthesia in patients undergoing upper and lower limb surgery

BACKGROUND

Tourniquet hypertension arising from tourniquet inflation remains a primary concern to the anaesthetist. One drug commonly used to manage tourniquet hypertension is ketamine. No studies have examined the effect of ketamine on tourniquet hypertension for a period of more than one hour or an infusion of the same.

OBJECTIVE

To compare the effect of an intravenous infusion of ketamine versus placebo on tourniquet induced hypertension in patients undergoing upper and lower limb surgery under general anaesthesia.

METHODS

Forty six adult patients scheduled for upper and lower limb surgery under general anaesthesia were randomized into two equal groups. The ketamine group received an intravenous bolus of 0.1mg/kg of ketamine followed by an infusion of 2ug/kg/min. The saline group received an intravenous bolus of physiological saline followed by an infusion of saline. All the patients were reviewed post-operatively. Data of the baseline characteristics, haemodynamic changes, post-tourniquet pain and side effects were collected. If post-tourniquet pain was present post-operatively, a visual analogue scale (VAS) was used to assess its severity.

RESULTS

46 patients successfully completed the trial. There were no significant differences between the groups for baseline patient demographics. The incidence of tourniquet hypertension was higher in the saline group (26.1%) compared with ketamine group (4.6%) with a 95% confidence interval. The difference was shown to be statistically significant ('P'<0.05). There was an increase in systolic blood pressure after 60 minutes of tourniquet inflation in the saline group but the difference was not statistically significant('P'>0.866). There were no significant differences between the groups as regards diastolic blood pressure and heart rate. VAS scores did not differ between the two groups. Statistically, there was no difference found between the two groups. Side effects were minimal in the ketamine group whilst in the saline group, nausea and vomiting were predominant but were also not statistically significant.

CONCLUSION

Based on the results of this study, there was a difference in the proportion of tourniquet hypertension between the ketamine and saline groups for patients undergoing upper and lower limb orthopaedic surgery under general anaesthesia.

American College of Foot and Ankle Surgeons® Clinical Consensus Statement: Perioperative Management

A wide range of factors contribute to the complexity of the management plan for an individual patient, and it is the surgeon's responsibility to consider the clinical variables and to guide the patient through the perioperative period. In an effort to address a number of important variables, the American College of Foot and Ankle Surgeons convened a panel of experts to derive a clinical consensus statement to address selected issues associated with the perioperative management of foot and ankle surgical patients.

Impact of remote ischaemic preconditioning on cerebral oxygenation during total knee arthroplasty

Background: Ischaemic reperfusion injury (IRI) after tourniquet release during total knee arthroplasty (TKR) is related to postoperative cerebral complications. Remote ischaemic preconditioning (RIPC) is known to minimise IRI in previous studies. Thus, we evaluated the effect of RIPC on regional cerebral oxygenation after tourniquet release during TKR. Methods: Patients undergoing TKR were randomly allocated to not receive RIPC (control group) and to receive RIPC (RIPC group). Regional cerebral oxygenation and pulmonary oxygenation were assessed up to 24 h postoperatively. The changes in serum cytokine and lactate dehydrogenase (LDH) levels were assessed and arterial blood gas analysis was performed. Total transfusion amounts and postoperative bleeding were also examined. Results: In total, 72 patients were included in the final analysis. Regional cerebral oxygenation (P < 0.001 in the left side, P = 0.003 in the right side) with pulmonary oxygenation (P = 0.001) was significantly higher in the RIPC group. The serum LDH was significantly lower in the RIPC group at 1 h and 24 h postoperatively (P < 0.001). The 24 h postoperative transfusion (P = 0.002) and bleeding amount (P < 0.001) were significantly lower in the RIPC group. Conclusions: RIPC increased cerebral oxygenation after tourniquet release during TKR by improving pulmonary oxygenation. Additionally, RIPC decreased the transfusion and bleeding amount with the serum LDH level.

Complete Neurological Recovery After Transesophageal Echocardiography-Guided Diagnosis and Management of Prolonged Cardiopulmonary Resuscitation

A 70-year-old man was scheduled for open reduction and internal fixation of his right knee fracture. When the tourniquet was deflated after 150 minutes, his arterial blood pressure and heart rate decreased precipitously. The patient was deemed to exhibit pulseless electrical activity. Cardiopulmonary resuscitation was initiated. The bispectral index reading improved to 25 to 30, but his end-tidal carbon dioxide was still very low (5 mm Hg). Transesophageal echocardiography showed a pulmonary embolism. Feedback from echo imaging improved the quality of chest compressions and motivated the resuscitation team to maintain the diastolic blood pressure>25 mm Hg. Although capnographic guidance was ineffective by itself, echocardiography monitoring was very helpful for showing the intracardiac events.

Change of QT variability index during general anesthesia

Background

The QT variability index (QTVI)–a non-invasive measure of beat-to-beat QT interval (QTI) fluctuations–is related to myocardial repolarization lability. The QTVI represents the relationship between QTI and the RR interval. Elevated QTVI is associated with an increased risk of malignant ventricular arrhythmias and sudden death. We investigated the influence of general anesthesia and tourniquets on the QTVI.

Methods

We studied fifty patients who received total knee replacement arthroplasty under sevoflurane anesthesia. We measured QTI, corrected QTI (QTc), T-wave peak-to-end interval (TPE), QTVI, and heart rate variability. All variables were calculated at baseline (B), 30 min after general anesthesia (A), 30 min (TQ1) and 60 min (TQ2) after tourniquet inflation, and at tourniquet deflation (TQR).

Results

Prolongation of QTI was detected at all times, and QTc was significantly prolonged TQR. TPE was unchanged during general anesthesia. The QTVI was significantly decreased and more negative during anesthesia and tourniquet inflation. After deflation of the tourniquet, the QTVI was restored to preanesthetic values. Low frequency (LF) was significantly decreased during general anesthesia, but high frequency (HF) was somewhat maintained, except at TQ2. The LF/HF ratio was significantly decreased at A and TQ2.

Conclusions

Sevoflurane based general anesthesia induced repolarization stability and, more negativity of the QTVI, in patients undergoing total knee replacement arthroplasty.

Compartment syndrome: diagnosis, management, and unique concerns in the twenty-first century

BACKGROUND

Compartment syndrome is an elevation of intracompartmental pressure to a level that impairs circulation. While the most common etiology is trauma, other less common etiologies such as burns, emboli, and iatrogenic injuries can be equally troublesome and challenging to diagnose. The sequelae of a delayed diagnosis of compartment syndrome may be devastating. All care providers must understand the etiologies, high-risk situation, and the urgency of intervention.

QUESTIONS/PURPOSES

This study was conducted to perform a comprehensive review of compartment syndrome discussing etiologies, risk stratification, clinical progression, noninvasive and invasive monitoring, documentation, medical-legal implication, and our step-by-step approach to compartment syndrome prevention, detection, and early intervention.

METHODS

A literature search was performed using the PubMed Database and the following search terms: "Compartment syndrome AND Extremity," "Compartment syndrome AND Gluteal," and Compartment syndrome AND Paraspinal." A total of 2,068 articles were identified. Filters allowed for the exclusion of studies not printed in English (359) and those focusing on exertional compartment syndrome (84), leaving a total of 1,625 articles available for review.

RESULTS

The literature provides details regarding the etiologies, risk stratification, clinical progression, noninvasive and invasive monitoring, documentation, medical-legal implication, and our step-by-step approach to compartment syndrome prevention, detection, and early intervention. The development and progression of compartment syndrome is multifactorial, and as complexity of care increases, the opportunity for the syndrome to be missed is increased. Recent changes in the structure of in-hospital medical care including resident work hour restrictions and the incorporation of midlevel providers have increased the frequency of "signouts" or "patient handoffs" which present opportunities for the syndrome to be mismanaged.

CONCLUSION

The changing dynamics of the health care team have prompted the need for a more explicit algorithm for managing patients at risk for compartment syndrome to ensure appropriate conveyance of information among team members.

The effect of tourniquet deflation on hemodynamics and regional cerebral oxygen saturation in aged patients undergoing total knee replacement surgery

BACKGROUND

Inflation and deflation of a pneumatic tourniquet used in total knee replacement surgery induces various changes in patient's hemodynamic and metabolic status, which may result in serious complications, especially in aged patients. Near-infrared spectroscopy (NIRS) is a monitoring device designed to estimate the regional cerebral oxygen saturation. We evaluated the effect of tourniquet deflation on hemodynamics and regional cerebral oxygen saturation in aged patients undergoing total knee replacement surgery, using NIRS.

METHODS

Twenty-eight American Society of Anesthesiologists physical status I or II patients, over the age of sixty-five years undergoing total knee replacement surgery, were included. Under general anesthesia, the mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), and regional cerebral oxygen saturation (rSO(2)) were recorded before induction of anesthesia and every 2 min after tourniquet deflation for 20 min. Arterial blood gas analysis was performed 5 min before, in addition to 0, and 10 min after tourniquet deflation.

RESULTS

The decrease of rSO(2) was not significant during 20-min deflation period. MAP, CO and SV showed significant decrease during 2 to 12, 4 to 6 and 2 to 6-min period after tourniquet deflation, respectively (P < 0.05). There was no relationship between a maximal decrease of MAP and rSO(2).

CONCLUSIONS

In aged patients undergoing total knee replacement surgery under general anesthesia, tourniquet deflation caused significant changes in hemodynamic and metabolic status, but not in regional cerebral oxygen saturation. It is recommended to monitor neurologic status, as well as hemodynamic and metabolic status to avoid serious complications, especially in aged patients.

Cuff width increases the serum biochemical markers of tourniquet-induced skeletal muscle ischemia in rabbits

Tourniquet application is a widely accepted adjuvant technique in extremity surgery. The purpose of this prospective, randomized trial was to evaluate the effect of cuff width on skeletal muscle ischemia-reperfusion injury. A 2- or 4-cm wide curved tourniquet cuff was applied around the midthigh of 36 New Zealand White rabbits and inflated to a pressure of 200 or 400 mm Hg for 2 hours: group A=2 cm to 200 mm Hg; group B=2 cm to 400 mm Hg; group C=4 cm to 200 mm Hg; group D=4 cm to 400 mm Hg. Blood levels of potassium, lactic acid, urea, lactic dehydrogenase, and creatinine phosphokinase MM isoenzyme (CPK-MM) were measured as basic indicators for limb ischemia before tourniquet inflation and 1, 5, and 30 minutes after cuff release.Potassium values did not differ among the 4 groups. Lactic acid and urea concentrations were always higher in the 400 mm Hg groups (B and D) (P<.001). However, cuff width did not affect their levels (P>.16). Lactic dehydrogenase and CPK-MM values were also greater in the 400 mm Hg groups at all times (P<.001). Further subgroup analysis of 200 mm Hg pressure groups showed higher lactic dehydrogenase (P<.02) but not CPK-MM (P>.9) concentrations in group C than in group A during the 30-minute period. At 400 mm Hg, lactic dehydrogenase and CPK-MM values were higher in group D compared with group B only 30 minutes after cuff deflation (P<.001). Broad tourniquets are associated with significantly greater and prolonged elevation of serum biochemical markers of inducible skeletal muscle ischemia-reperfusion injury compared with narrow ones. This difference is more prominent when a wide cuff is inflated to a high pressure.

Relation between preoperative autonomic function and blood pressure change after tourniquet deflation during total knee replacement arthroplasty

Background

Tourniquets are used to provide a bloodless surgical field for extremities. Hypotension due to vasodilation and bleeding after tourniquet deflation is a common event. Hemodynamic stability is modulated by the autonomic nervous system (ANS). Heart rate variability (HRV) is a sensitive method for detecting individuals who may be at risk of hemodynamic instability during general anesthesia. The purpose of this study was to investigate ANS function to predict hypotension after tourniquet deflation.

Methods

Eighty-six patients who underwent total knee replacement arthroplasty (TKRA) were studied. HRV, systolic blood pressure variability (SBPV) and baroreflex sensitivity (BRS) were analyzed. We assigned two groups depending on the lowest systolic blood pressure (SBP) or mean BP (MBP) after tourniquet release (Group H; SBP < 80 mmHg or MBP < 60 mmHg, Group S; SBP > 80 mmHg and MBP > 60 mmHg).

Results

Fifteen patients developed severe hypotension and ten patients were treated with ephedrine. Of the parameters of HRV, SBPV, and BRS, only BRS_SEQ was significant being low in Group H. BRS and high-frequency SBPV were correlated with the degree of MBP change after tourniquet deflation.

Conclusions

Preoperative low BRS is associated with hypotension after tourniquet deflation, suggesting the importance of baroreflex regulation for intraoperative hemodynamic stability.

Antioxidant effects of propofol on tourniquet-induced ischemia-reperfusion injury: an experimental study

PURPOSE

This experimental study aimed to investigate the antioxidant effects of propofol anesthesia at induction doses in a rat skeletal muscle ischemia/reperfusion injury model.

METHODS

Twenty-six rats were randomly divided into three groups to receive one of the following interventions: sham operation (n = 6), ischemia/reperfusion (I/R) injury (n = 10), or propofol administration in addition to I/R injury (n = 10). I/R injury was attained by 2-h clamping of femoral artery followed by 3-h perfusion. Then blood and tissue samples were collected for biochemical analysis and histopathologic examination. Glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) enzyme activities and nitric oxide (NO) and malondialdehyde (MDA) levels were measured in both plasma and muscle tissue. In addition, catalase (CAT) activity and protein carbonyl (PC) content were measured in muscle tissue.

RESULTS

I/R group had significantly higher SOD activity (9.05 versus 5.63 and 6.18 U/mL, P < 0.05) and NO level (46.77 versus 30.62 and 33.90 μmol/L, P < 0.05) compared with sham-operated group and I/R plus propofol group. In addition, GSH-Px activity of the I/R group was significantly higher than sham-operated group (1.26 versus 1.05 U/mL, P < 0.05). I/R group had significantly higher tissue activities of CAT (0.11 versus 0.06 and 0.04 k/g protein, P < 0.05) and SOD (0.12 versus 0.08 and 0.07 U/mg protein, P < 0.05) compared with the sham and I/R plus propofol group. Histopathologic examination showed that I/R plus propofol group had significantly lower degeneration (P = 0.021) and inflammation (P = 0.028) scores compared with I/R group.

CONCLUSION

Propofol anesthesia seems to enhance the antioxidant capacity against tourniquet induced ischemia-reperfusion injury.

Silicone ring versus pneumatic cuff tourniquet: a comparative quantitative study in healthy individuals

INTRODUCTION

The aim of the present study was to compare a new silicone ring tourniquet (SRT) with a classic pneumatic cuff tourniquet (PT) in terms of tolerance and recovery time following their use in healthy volunteers.

METHODS

Both tourniquets were applied in the arm and thigh of 15 healthy unmedicated volunteers. PT pressure was kept at 100 mmHg above the systolic blood pressure. The appropriate model of the SRT was used according to the systolic blood pressure. Pain was assessed by visual analogue scale and arterial blood pressure, pulse rate and oxygen saturation were monitored in all volunteers.

RESULTS

There was no statistically significant difference in tolerance time between SRT and PT in the arm (19.13 vs. 18.25 min) and thigh (21.52 vs. 21.39 min) nor in recovery time between the two devices.

CONCLUSION

The SRT performed similarly to the classic PT in terms of tolerance and recovery time when applied in the arm and thigh of unmedicated healthy volunteers.

Effect of high-dose vitamin C on oxygen free radical production and myocardial enzyme after tourniquet ischaemia-reperfusion injury during bilateral total knee replacement

This study investigated the effects of high-dose vitamin C on oxygen free radical production and cardiac enzymes after tourniquet application and ischaemia-reperfusion injury during bilateral total knee replacement (TKR) in elderly patients. In the vitamin C (VC) group (VC group, n = 16), during surgery, patients received a priming bolus of 0.06 g/kg vitamin C with 100 ml saline followed by 0.02 g/kg vitamin C mixed with 30 ml saline, intravenously. The control group (n = 16) received no intra-operative vitamin C. In the VC group, malondialdehyde levels were lower, and arterial oxygen tension and mean blood pressure were higher, than in controls after post-operative deflation of both knee tourniquets. Troponin I levels were lower in the VC group than in controls 8 h post-operation. Administering high-dose vitamin C during bilateral TKR could prevent oxygen free radical production and a decline in arterial oxygen tension and mean blood pressure induced by ischaemia-reperfusion injury, thereby protecting the myocardium.

Effects of the tourniquet deflation on bispectral index during knee arthroscopic surgery under the general anesthesia

BACKGROUND

Tourniquet deflation during lower extremity surgery affects the hemodynamics and metabolism of the patient, which can affect brain activity. This study examined the changes in brain activity during tourniquet deflation by measuring the bispectral index (BIS).

METHODS

The BIS was measured during surgery in forty patients who had received knee arthroscopic surgery under general anaesthesia. The BIS was measured 5 minutes before deflation (DB5) and 5 minutes after deflation (DA5).

RESULTS

The BIS at DB5 and DA5 was 50.2 +/- 9.9 and 44.4 +/- 10.4, respectively. The BIS of DA5 was significantly lower than that of DB5 (P < 0.05).

CONCLUSIONS

Tourniquet deflation during lower extremity surgery decreases the BIS associated with hemodynamic and metabolic changes. However, its clinical significance in neurologically critical patients, such as geriatric or neurologically disabled patients, remains to be clarified.

Effects of acetylcysteine and ischaemic preconditioning on muscular function and postoperative pain after orthopaedic surgery using a pneumatic tourniquet

BACKGROUND AND OBJECTIVE

The use of a pneumatic tourniquet can induce muscular and neurological complications in the operated limb. The genesis of these injuries could involve an ischaemia/reperfusion phenomenon and a compression under the cuff. We evaluated effects of an antioxidant, acetylcysteine and ischaemic preconditioning on the rhabdomyolysis and postoperative pain following a knee ligamentoplasty using a pneumatic tourniquet.

METHODS

We included 31 patients scheduled for a knee ligamentoplasty randomly assigned in three groups (control, acetylcysteine 1200 mg the day before and 600 mg at the operative day, ischaemic preconditioning).

RESULTS

There was a moderate rise in myoglobin and creatinine phosphokinase with no significant difference between the three groups. The muscular functional parameters were similar in all the groups. However, the morphine consumption within the first 48 h was smaller in the treatment groups (0.22 +/- 0.31 mg kg-1 and 0.22 +/- 0.23 mg kg-1 in the preconditioning and antioxidant groups, respectively) than in the control group (0.47 +/- 0.33 mg kg-1, P <0.05).

CONCLUSIONS

Acetylcysteine and ischaemic preconditioning do not decrease the extent of rhabdomyolysis related to the use of a pneumatic tourniquet and do not improve the postoperative muscle recovery. On the other hand, they allow a significant reduction in the postoperative morphine consumption.

Use of tissue ultrafiltration for treatment of compartment syndrome: a pilot study using porcine hindlimbs

OBJECTIVES

To demonstrate the efficacy of compartment syndrome ultrafiltration for the treatment of acute compartment syndrome in an animal model. Our hypothesis is the removal of interstitial fluid will result in a reduction of intramuscular pressure compared with untreated controls in a model of bilateral induced compartment syndrome.

DESIGN

Controlled experimental model.

SETTING

Animal research facility.

PATIENTS/PARTICIPANTS

Three pairs of porcine hindlimbs.

INTERVENTION

Acute compartment syndrome was created in the pig hindlimb by infusion of saline to maintain the intramuscular pressure 30 mm Hg greater than the animal's mean arterial pressure for 8 hours. After a 2-hour reperfusion interval, ultrafiltration (removal of fluid through 1 mm diameter porous catheters, connected to -500 mm Hg suction) was commenced in 1 limb only and continued for 9.5 hours.

MAIN OUTCOME MEASURES

Intramuscular pressure, ultrafiltrate volume, ultrafiltrate and serum levels of creatine kinase and lactate dehydrogenase, histologic measurement of extracellular and intracellular edema, as well as the degree of cellular necrosis.

RESULTS

Intramuscular pressure tended to be lower on the treated side at the end of the treatment period [treated leg: 9.3 +/- 4.0 mm Hg (+/- SE), control leg: 19.3 +/- 1.4 mm Hg, P = 0.03]. Analysis of ultrafiltrate fluid showed that levels of creatine kinase and lactate dehydrogenase were elevated compared with serum levels. Creatine kinase levels in serum were measured at 4150 +/- 780 U/L, whereas ultrafiltrate levels of creatine kinase were 28,700 +/- 17,700 U/L (+/- SE) (P = 0.1). Lactate dehydrogenase was measured at 1950 +/- 180 U/L in serum, but markedly elevated in ultrafiltrate [160,000 +/- 88,900 U/L (+/- SE), P = 0.05]. Quantification of cellular and interstitial dimensions showed no difference in control and experimental limbs. Quantification of the degree of muscle necrosis revealed 6.1 +/- 2.7% necrosis in the treated limb compared to 11.3 +/- 1.6% necrosis in the control group (P = 0.02, df = 2, 1-tailed paired t test).

CONCLUSION

This pilot study demonstrates the feasibility of tissue ultrafiltration for reduction of intramuscular pressure in this porcine model. Further studies are underway. Compartment syndrome ultrafiltration may be useful prophylactically in patients at risk for acute compartment syndrome. Sampling of interstitial fluid and frequent measurement of intramuscular pressure may allow earlier diagnosis and treatment of acute compartment syndrome, whereas the reduction of tissue pressure by compartment syndrome ultrafiltration may prevent acute compartment syndrome from occurring. Additionally, compartment syndrome ultrafiltration will not hinder the ability of clinicians to use the clinical examination and pressure monitoring as the gold standard.

Circulatory, respiratory and metabolic changes after thigh tourniquet release in combined epidural-propofol anaesthesia with preservation of spontaneous respiration

Twelve elderly patients undergoing total knee arthroplasty received lumbar epidural anaesthesia and propofol infusion at 5 mg.kg(-1).h(-1) following a 1.5-2.0 mg.kg(-1) bolus dose with preservation of spontaneous respiration via a laryngeal mask airway. Circulatory, respiratory and metabolic variables were measured before and 1, 3, 5, 15 and 30 min after release of a pneumatic thigh tourniquet. The blood pressure was decreased at all time-points and the respiratory rate increased at 1 min. The P(a)CO(2) was increased only at 1 min. Arterial blood pH and base excess were decreased at 1 and 3 min and 1, 3 and 5 min, respectively. Arterial blood lactate levels were increased at all times. These characteristics were considered to be identical to those under regional anaesthesia with conscious spontaneous respiration, showing that spontaneous respiration under this anaesthetic regimen has a similar respiratory capacity to that of conscious spontaneous respiration.

Systemic reperfusion injury during arm replantation requiring intraoperative amputation

This case describes the attempted replantation of an arm following its traumatic amputation. After a five-and-a-half hour ischaemic time, perfusion of the arm was re-established. However over the ensuing hours, the patient developed hyperkalaemia, acidaemia and severe hypotension requiting high dose inotropic support. Ultimately re-amputation was necessary to treat the systemic effects of the ischaemia reperfusion syndrome.

Tourniquet-induced systemic inflammatory response in extremity surgery

BACKGROUND

Tourniquet-induced reperfusion injury in animals produces significant systemic inflammatory effects. This study investigated whether a biologic response occurs in a clinically relevant model of tourniquet-induced reperfusion injury.

METHODS

Patients undergoing elective knee arthroscopy were prospectively randomized into controls (no tourniquet) and subjects (tourniquet-controlled). The effects of tourniquet-induced reperfusion on monocyte activation state, neutrophil activation state, and transendothelial migration (TEM) were studied. Changes in the cytokines implicated in reperfusion injury, tumor necrosis factor-alpha, interleukin (IL)-1beta, and IL-10 were also determined.

RESULTS

After 15 minutes of reperfusion, neutrophil and monocyte activation were significantly increased. Pretreatment of neutrophils with pooled subject (ischemia-primed) plasma significantly increased TEM. In contrast, TEM was not significantly altered by ischemia-primed plasma pretreatment of the endothelial monolayer. Significant elevation of tumor necrosis factor-alpha and IL-1beta were observed in subjects compared with controls after 15 minutes of reperfusion. There was no significant difference in serum IL-10 levels between the groups at all the time points studied.

CONCLUSION

These results indicate a transient neutrophil and monocyte activation after tourniquet-ischemia that translates into enhanced neutrophil transendothelial migration with potential for tissue injury.

The effects of propofol or halothane on free radical production after tourniquet induced ischaemia-reperfusion injury during knee arthroplasty

BACKGROUND

Ischaemia-reperfusion injury following tourniquet release is a good in vivo model for evaluating acute conditions. The aim of the study was to investigate the effects of propofol or halothane anaesthesia on oxidative stress by determining malondialdehyde (MDA) levels during knee arthroplasty.

METHODS

Thirty patients undergoing orthopaedic surgery were divided into two groups. Anaesthesia was induced with either fentanyl 100 microg and propofol 2 mg kg(-1) (Group 1) or fentanyl 100 microg and thiopentone 5 mg kg(-1) (Group 2) and maintained with infusion of propofol in Group 1 or inhalation of halothane in Group 2. ECG, SpO2, EtCO2, and mean arterial pressure (MAP) were monitored. Venous and arterial blood samples were obtained at different measurement times for MDA and blood gas analyses.

RESULTS

There was a significant decrease in MAP in the 1st and 5th minutes after tourniquet release (ATR) when compared with the 5th minute before tourniquet release (BTR) in both groups. Heart rate (HR) increased significantly in the 1st minute ATR in Group 1 only. EtCO2 increased significantly in the 1st and 5th minutes ATR, SpO2 decreased in the 1st minute ATR in both groups. There was a significant decrease in pH and increase in pCO2 at 1, 5 and 30 min ATR in both groups. pO2 values decreased in the 1st minute ATR in Group 1 only and returned to control values at 5 min ATR and decreased at 30 min ATR in the recovery room in both groups. The differences in SaO2 were similar to SpO2. MDA levels decreased before and after release of tourniquet when compared to baseline in both groups. However, there was a statistically significant decrease only in Group 1.

CONCLUSION

Propofol may be a good choice of anaesthetic when an ischaemia-reperfusion injury is anticipated as in orthopaedic surgery requiring a tourniquet, due to its antioxidant properties, but halothane needs further study.

Pneumatic tourniquets in extremity surgery

Pneumatic tourniquets maintain a relatively bloodless field during extremity surgery, minimize blood loss, aid identification of vital structures, and expedite the procedure. However, they may induce an ischemia-reperfusion injury with potentially harmful local and systemic consequences. Modern pneumatic tourniquets are designed with mechanisms to regulate and maintain pressure. Routine maintenance helps ensure that these systems are working properly. The complications of tourniquet use include postoperative swelling, delay of recovery of muscle power, compression neurapraxia, wound hematoma with the potential for infection, vascular injury, tissue necrosis, and compartment syndrome. Systemic complications can also occur. The incidence of complications can be minimized by use of wider tourniquets, careful preoperative patient evaluation, and adherence to accepted principles of tourniquet use.

The arterial tourniquet: pathophysiological consequences and anaesthetic implications

The arterial tourniquet is widely used in upper and lower extremity surgery and in intravenous regional anaesthesia. The local and systemic physiological effects and the anaesthetic implications are reviewed. Localised complications result from either tissue compression beneath the cuff or tissue ischaemia distal to the tourniquet. Systemic effects are related to the inflation or deflation of the tourniquet. Safe working guidelines for the application of an arterial tourniquet have not been clearly defined.

Hypotensive epidural anesthesia in total knee replacement without tourniquet: reduced blood loss and transfusion

BACKGROUND AND OBJECTIVES

[corrected] For decades, hypotensive anesthesia has been used in an attempt to reduce intraoperative blood loss. Hypotensive epidural anesthesia (HEA) is a relatively new technique in hypotensive anesthesia. Use of a tourniquet has been shown to be associated with a higher risk of cardiovascular and thromboembolic complications. The effect of HEA on blood loss and need for transfusion in total knee replacement (TKR) is not known.

METHODS

Thirty consecutive patients scheduled for TKR were randomized to HEA without tourniquet or spinal anesthesia with the use of a tourniquet (SPI). HEA was performed as an epidurally induced sympathetic block and there was an infusion of low-dose epinephrine to stabilize the circulation.

RESULTS

Intraoperative mean arterial blood pressure was 48 mm Hg (HEA) versus 83 mm Hg (SPI) (P <.001). Intraoperative blood loss was 146 mL (HEA) versus 13 mL (SPI) (P <.001). Postoperative blood loss at any time was significantly reduced in the HEA group, and total loss of blood was 1,056 mL (HEA) versus 1,826 mL (SPI) (P <.001). Half of the bleeding took place during the first 3 postoperative hours and 80% during the first 24 hours. In the HEA group, 57% of the patients went through surgery and the hospital stay without receiving blood transfusion versus 19% in the SPI group (P <.05). There was a significantly reduced amount of blood transfusion in the HEA group (193 mL) versus 775 mL in the SPI group (P <.005). No cardiopulmonary, cerebral, or renal complications were registered.

CONCLUSIONS

We conclude that HEA is a safe technique that allows TKR without a tourniquet. Compared with spinal anesthesia, the use of HEA for TKR significantly reduces blood loss and the need for blood transfusion.

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.

IMP and AMP deaminase in reperfusion injury down-regulates neutrophil recruitment

We examined gene regulation in murine lungs after hind-limb vessel occlusion and reperfusion. A rapid increase of transcript for the AMP deaminase 3 gene (AMPD3) and its enzymatic activity (EC) generating inosine monophosphate (IMP) were identified with transcripts located in bronchial and alveolar epithelium. AMP deaminase inhibitor decreased IMP levels and significantly enhanced neutrophil recruitment within lung tissue during reperfusion. In addition, IMP inhibited cytokine-initiated neutrophil infiltration in vivo and selectively attenuated neutrophil rolling by 90% in microvessels. We prepared labeled IMP and demonstrated that IMP specifically binds to neutrophils. IMP also stimulated binding of gamma-[(35)S]thio-GTP, suggesting that IMP is a potent regulator of neutrophils. Taken together, these results elucidate a previously unrecognized mechanism that protects tissues from the potentially deleterious consequences of aberrant neutrophil accumulation. Moreover, they are relevant for new therapeutic approaches to regulate neutrophil responses in inflammation and vascular disease.

Renal dysfunction after total knee replacement is not aggravated by bone cement

BACKGROUND

Total knee replacement (TKR) has been associated with postoperative renal dysfunction. The use of monomeric methylmethacrylate (MMA) bone cement causes hypotension by several mechanisms.

METHODS

In 30 patients undergoing TKR with (n = 16), or without (n = 14) bone cement, serum levels of creatinine, cystatin C and creatine kinase (CK) and urinary levels of creatinine and markers for glomerular (albumin, IgG) and tubular (protein HC) function were recorded preoperatively and on days 1, 2, 4 and 8 postoperatively.

RESULTS

There were no changes in serum creatinine. Both groups had a transient, 5-fold rise in CK and a continuous increase in cystatin C. The urinary concentration of proteins increased postoperatively with a peak in the glomerular markers on day 1 and in the tubular marker on day 2. There were no significant differences in proteinuria between the groups. The 95% CIs for the difference in the means of the AUCs of the logarithmically transformed values for the proteins were never more than 19%. On day 8 all proteins had returned to their preoperative levels.

CONCLUSION

Postoperatively, there was a transient increased leakage of proteins, indicating glomerular and tubular dysfunction. This was not influenced by the use of MMA bone cement.

Metabolic effects of a low-pressure tourniquet system compared with a high-pressure tourniquet system in arthroscopic anterior crucial ligament reconstruction

BACKGROUND

Bloodless field is an integral part of orthopedic surgery. Use of tourniquet is associated with a risk of skeletal muscle ischemia and reperfusion injury. The purpose of this prospective, open-randomized study was to determine if the use of a tourniquet system using low pressure, with a wide, curved cuff connected to a microprocessor pump is safer than a standard tourniquet system with a narrow, straight cuff using higher inflation pressures.

METHODS

Test parameters used as markers of muscular injury and anaerobic metabolism were femoral vein blood lactate, pH, pCO2, pO2, potassium, aspartate aminotransferase activity, myoglobin, creatine kinase and creatine kinase-MM activity levels after release of tourniquet. Twenty-six ASA I-II patients were studied.

RESULTS

Tourniquet times varied between 30 and 144 min. Deflation of the tourniquet caused a significant release of lactate, myoglobin and potassium detected in the femoral vein blood. pCO2 increased, but pH and pO2 decreased after tourniquet deflation. There were no differences between the study groups. The tourniquet time showed a significant correlation with femoral vein lactate.

CONCLUSION

The main finding of this study was that the metabolic changes were more pronounced with the longer tourniquet time. The results of the study did not show any difference on metabolic markers of muscular injury during the first hour after release of tourniquet between the two tourniquet systems.