Tourniquet-induced Ischemia-reperfusion Injury Research Articles

Comparison of the effects of axillary brachial plexus block, inhalation anesthesia, and total intravenous anesthesia on tourniquet-induced ischemia-reperfusion injury in upper extremity surgery.

Post-ischemia reperfusion can lead to oxidative stress and an increase in oxidative markers. Employing preventive strategies and antioxidant agents may help mitigate ischemia-reperfusion injury (IRI). The use of a tourniquet in extremity surgery has been associated with IRI. This study aims to investigate the impact of three different approaches- brachial plexus block, total intravenous anesthesia (TIVA), and inhalation anesthesia-on IRI during upper extremity surgery using a tourniquet. Patients aged 18 to 45 with American Society of Anesthesiologists (ASA) I-II scores were randomly assigned to one of three groups: Group A received an axillary block with bupivacaine; Group I underwent inhalation anesthesia with sevoflurane; and Group T received TIVA with propofol and remifentanil infusion. Blood samples were collected to measure glucose, lactate, total anti-oxidant status (TAS), total oxidant status (TOS), and ischemia-modified albumin (IMA) levels at various time points: before anesthesia (t1), 1 minute before tourniquet release (t2), 20 minutes after tourniquet release (t3), and 4 hours after tourniquet release (t4). In Group I, lactate levels at t3, and glucose levels at t2 and t3, were higher compared to the other groups. Group A exhibited lower IMA levels at t2, t3, and t4 than the other groups. Additionally, Group I had lower IMA levels at t2, t3, and t4 compared to Group T. TAS levels were higher in Group I at t2, t3, and t4 compared to the other groups. TOS levels at t2 and t3 were lower in Group A than in Group I. Axillary anesthesia results in a sympathetic block, promoting better perfusion of the upper extremity. This study demonstrated lower levels of oxidative stress markers with axillary plexus block. Therefore, these results suggest that the axillary block has the potential to mitigate IRI.

Rapsyn overexpression improves recovery of the neuromuscular junction from tourniquet-induced ischemia-reperfusion injury in mouse hindlimb

The neuromuscular junction (NMJ) is an important factor to influence skeletal muscle contractile function. Tourniquet-induced ischemia-reperfusion (IR) results in the fragmentation of nicotinic acetylcholine receptors (nAChR) clusters in the NMJ and impairs neural controlled skeletal muscle contraction. Rapsyn, a cytoplasmic nAChR-associated protein concentrates and anchors nAChRs in the postsynaptic membrane and participates in the nAChR assembly at NMJ. Here, we observed the effect of overexpression of Rapsyn on morphological and functional recovery of the NMJ from tourniquet-induced IR injuries in mouse hindlimb. Unilateral hindlimb of C57/BL6 mice were subjected to 3 hours of ischemia by placing a rubber band and followed 6 weeks of reperfusion. Ad-m-RAPSN (5.2 x 1010 PFU/ml) was injected into gastrocnemius muscle (50 μl) by Hamilton microliter syringe after 2 weeks of tourniquet-induced IR. After 6 weeks of IR, the sciatic nerve-stimulated gastrocnemius muscle contraction and endplate potential (EPP) were recorded in in-situ muscle samples; the NMJs were labelled with alpha-bungarotoxin (BTX) and nerofilment-200 (NF-200) + synaptophysin (Syn) antibodies, and NMJ images were captured with Zeiss LSM 800. After 6 weeks of IR, NMJs in the gastrocnemius muscle showed significantly fragmented nAChR clusters (9.3 ± 0.7 vs. sham 1.7 ± 0.1 for numbers of fragments) with low rapsyn expression, and the EPP (15.29 ± 0.93 mV vs. sham 26.87 ± 0.89 mV) and nerve-stimulated muscle contraction (117.2 ± 8.5 g vs. sham 157.9 ± 4.9 g) were reduced. Ad-m-RAPSN injection increased rapsyn expression, mitigated fragmentation of nAChR clusters (3.2 ± 0.3), increased the EPP (20.35 ± 0.86) and nerve-stimulated muscle contraction (138.1 ± 3.5 g). The data suggest that tourniquet-related IR induces AChR cluster fragmentation and impairs NMJ function, and rapsyn overexpression improves the morphological and functional recovery of the NMJ from tourniquet-induced IR injuries.. This research is supported by the NIH/NIGMS 1R01GM145736 to Y-LL. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Effect of Infraclavicular Block on Tourniquet-Induced Ischaemia Reperfusion Injury: A Prospective Randomized Controlled Study

The Effect of Infraclavicular Block on Tourniquet-Induced Ischaemia Reperfusion Injury: A Prospective Randomized Controlled Study

Tourniquet-induced ischemia creates increased risk of organ dysfunction and mortality following delayed limb amputation

Tourniquets are critical for the control of traumatic extremity hemorrhage. In this study, we sought to determine, in a rodent blast-related extremity amputation model, the impact of prolonged tourniquet application and delayed limb amputation on survival, systemic inflammation, and remote end organ injury. Adult male Sprague Dawley rats were subjected to blast overpressure (120±7 kPa) and orthopedic extremity injury consisting femur fracture, one-minute soft tissue crush injury (20 psi), ± 180 min of tourniquet-induced hindlimb ischemia followed by delayed (60 min of reperfusion) hindlimb amputation (dHLA). All animals in the non-tourniquet group survived whereas 7/21 (33%) of the animals in the tourniquet group died within the first 72 h with no deaths observed between 72 and 168 h post-injury. Tourniquet induced ischemia-reperfusion injury (tIRI) likewise resulted in a more robust systemic inflammation (cytokines and chemokines) and concomitant remote pulmonary, renal, and hepatic dysfunction (BUN, CR, ALT. AST, IRI/inflammation-mediated genes). These results indicate prolonged tourniquet application and dHLA increases risk of complications from tIRI, leading to greater risk of local and systemic complications including organ dysfunction or death. We thus need enhanced strategies to mitigate the systemic effects of tIRI, particularly in the military prolonged field care (PFC) setting. Furthermore, future work is needed to extend the window within which tourniquet deflation to assess limb viability remains feasible, as well as new, limb-specific or systemic point of care tests to better assess the risks of tourniquet deflation with limb preservation in order to optimize patient care and save both limb and life.

Effect of Preoperative Administration of Oral Melatonin on Pneumatic Tourniquet-Induced Ischemia-Reperfusion Injury in Orthopedic Surgery of Lower Extremities: A Randomized Clinical Trial.

Background: Ischemic reperfusion injury (IRI) causes cellular damage and dysfunction. The present study aimed to evaluate the effect of melatonin on pneumatic tourniquet-induced IRI in orthopedic surgery of the lower extremities.Methods: A randomized clinical trial was conducted at Chamran Hospital, Shiraz University of Medical Sciences (Shiraz, Iran), from September to November 2019. The target population was patients scheduled for elective orthopedic surgery of the lower extremities. A total of 67 patients were randomly divided into two groups, placebo (n=34) and melatonin (n=33). The groups received 10 mg melatonin or placebo the night before surgery and two hours before surgery. Primary outcome variables were the serum levels of superoxide dismutase (SOD) and malondialdehyde (MDA). Hemodynamic parameters, sedation score, and drug side effects were also evaluated. Data were analyzed using SPSS version 21.0 software. P<0.05 was considered statistically significant.Results: In the analysis phase, due to loss to follow-up (n=26), 41 patients divided into two groups of melatonin (n=20) and placebo (n=21) were evaluated. There was no significant difference in demographic data, duration of surgery (P=0.929), and tourniquet time (P=0.496) between the groups. The serum levels of SOD and MDA were not significantly different between the groups (P=0.866 and P=0.422, respectively), nor were the incidence of postoperative nausea (P=0.588) and patients’ satisfaction (P=0.088). However, the postoperative sedation score and vomiting between the groups were significantly different (P<0.001).Conclusion: Administration of 10 mg melatonin provided effective sedation, but had no significant effect on the serum levels of SOD and MDA, nor on pneumatic tourniquet-induced IRI in orthopedic surgery of the lower limbs.Trial registration number: IRCT20141009019470N87.

Effects of Dexmedetomidine and Oxycodone on Neurocognitive and Inflammatory Response After Tourniquet-Induced Ischemia-Reperfusion Injury.

To evaluate the effects of dexmedetomidine (Dex) and oxycodone (Oxy) on neurocognitive and inflammatory response after tourniquet-induced ischemia-reperfusion (I/R) injury. C57/BL6 mice were used to construct the mouse model of tourniquet-induced I/R injury. Mice (n = 48) were randomly divided into sham, I/R, Dex or Oxy group. Morris water maze test was performed to assess the spatial learning and memory function. The expression of NF-κB, TLR4, NR2B, M1 (CD68 and TNF-α) and M2 (CD206 and IL-10) polarization markers in mice hippocampus were detected by western blot or immunofluorescent staining. Spontaneous excitatory post-synaptic currents (sEPSCs) were recorded by electrophysiology. Dex treatment alleviated I/R-induced declines in learning and memory (p<0.05), while Oxy had no significant effect on it. Compared with I/R group, Dex and Oxy treatment down-regulated the expression of NF-κB, TLR4, TNF-α and CD68 (all p<0.05), while no significantly different was found in CD206 and IL-10. In addition, Dex treatment down-regulated the expression of NR2B and reduced the frequency and amplitude of sEPSCs in I/R model mice (all p<0.05), while Oxy had no significant effect on them. Tourniquet-induced I/R could impair the neurocognitive function of mice. Dex treatment could alleviate I/R-induced neurocognitive disorder by inhibiting abnormal synaptic transmission in hippocampal neurons. Both Dex and Oxy could alleviate the inflammatory response likely by inhibiting the polarization of microglia toward M1 phenotype via TLR4/NF-κB pathway. Future studies are needed to further examine the effects of Dex on neurocognitive disorder after tourniquet-induced I/R injury and investigate the exact mechanism.

Does hyperbaric oxygen pretreatment with 100% oxygen attenuate tourniquet‐induced acute ischemia‐reperfusion injury in mouse hindlimb?

Tourniquet-induced ischemia-reperfusion (IR) leads to an increase in reactive oxygen species (ROS) production and tissue necrosis and apoptosis during reperfusion, which disrupts the recovery of skeletal muscle contraction. Hyperbaric oxygen (HBO) therapy exposes patients to high oxygen levels at an increased pressure, which increases the amount of ROS in tissues. Using HBO therapy as a pretreatment can promote ischemic tolerance by increasing antioxidant effects in these tissues before the IR injury. In this study, we observed the effects of HBO pretreatment with 100% oxygen at 2.5 ATA on tourniquet-induced IR injury in mice. C57/BL6 mice were treated with 100% oxygen for 60 minutes at 2.5 ATA in a HBO chamber. A rubber band was placed at the hip joint of the unilateral hindlimb of the mice to induce ischemia for 3 hours, which was followed by rubber band release and subsequent reperfusion for 48 hours. All staining and measurements were performed after the 48 hours of reperfusion. TTC staining of the gastrocnemius muscle showed no significant change in IR-induced infarct size after HBO pretreatment. ROS level was decreased in the gastrocnemius muscle of HBO-pretreated IR mice compared to non-HBO-pretreated IR mice. IR mice pretreated with HBO showed a decrease in ATP level in the gastrocnemius muscle compared to mice without HBO treatment. The data suggest that one hour HBO pretreatment with 100% oxygen at 2.5 ATA increases oxidative metabolism but does not decrease tissue necrosis in mice with tourniquet-induced IR injury.

Effects of preoperative low-intensity training with slow movement on early quadriceps weakness after total knee arthroplasty in patients with knee osteoarthritis: a retrospective propensity score-matched study

BackgroundSevere and early quadriceps weakness (QW) after total knee arthroplasty (TKA), which is caused by acute inflammation resulting from surgical trauma and tourniquet-induced ischemia-reperfusion (IR) injury, can be especially problematic. We focused on tourniquet-induced IR injury, because it has been shown to be preventable through ischemic and exercise preconditioning. Low-intensity resistance exercise with slow movement and tonic force generation (LST) share some similarities with ischemic and exercise preconditioning. The present study primarily aimed to clarify the efficacy of preoperative LST program as prehabilitation for early QW among patients with TKA using propensity score matching analysis.MethodsThis single-center retrospective observational study used data from patients with knee osteoarthritis (n = 277) who were scheduled to undergo unilateral TKA between August 2015 and January 2017. Those with missing outcome data due to their inability to perform tests were excluded. The LST group included participants who performed LST and aerobic exercise (LST session) more than seven times for three months prior to surgery. The control group included participants who performed less than eight LST sessions, a general and light exercise or had no exercise for three months prior to surgery. Knee circumference, thigh volume, knee pain during quadriceps strength test (QST) and timed up and go test (TUG), quadriceps strength, and TUG were measured before and 4 days after surgery. Knee swelling, thigh swelling, Δknee pain, QW, and ΔTUG were determined by comparing pre- and postoperative measurements.ResultsPropensity score matching generated 41 matched pairs who had nearly balanced characteristics. The LST group had a significantly lower knee and thigh swelling, QW, and ΔTUG compared to the control group (all, p < 0.05). No significant differences in Δknee pain during the QST and TUG were observed between both groups (both, p > 0.05).ConclusionsThe present study demonstrated the beneficial effects of preoperative LST program on knee swelling, thigh swelling, QW, and walking disability immediately after TKA.

MicroRNA-153-3p increases autophagy in sevoflurane-preconditioned mice to protect against ischaemic/reperfusion injury after knee arthroplasty.

The use of tourniquet during total knee arthroplasty (TKA) can result in ischaemia/reperfusion injury (IRI). Of interest, microRNAs (miRs) are reported to be involved in various kinds of IRI due to their ability in modulating autophagy. Therefore, the study aimed to investigate the effect of miR‐153‐3p on autophagy in IRI in vitro and in vivo under sevoflurane preconditioning. In the in vitro model, chondrocytes from naive mice were treated with 0% FBS alone or in combination with sevoflurane. Additionally, in vivo assays were conducted in mouse models with tourniquet‐induced IRI after TKA under or without sevoflurane preconditioning. The pathological observation in vivo validated that sevoflurane preconditioning protected the knee joint against IRI. Moreover, miR‐153‐3p expression was diminished in chondrocytes of the in vitro model and in cartilage tissue of the in vivo model, but its expression was appreciably up‐regulated in the presence of sevoflurane preconditioning. Mechanistic study showed that miR‐153‐3p disrupted the interaction between Bcl‐2 and Beclin1 by targeting Bcl‐2, thereby facilitating autophagy in chondrocytes under sevoflurane preconditioning. Furthermore, the experiments in human chondrocytes also verified the protective effects of miR‐153‐3p against IRI were realized through inhibiting Bcl‐2. Collectively, miR‐153‐3p overexpression blocks the interaction between Bcl‐2 and Beclin1 via down‐regulation of Bcl‐2 to promote autophagy of chondrocytes, thus protecting knee joint against IRI after TKA under sevoflurane preconditioning.

The investigation of the preventive effects of Coenzyme Q10 and Berberine for tourniquet induced ischemia-reperfusion injury on skeletal muscle in rat hindlimb

The investigation of the preventive effects of Coenzyme Q10 and Berberine for tourniquet induced ischemia-reperfusion injury on skeletal muscle in rat hindlimb

The investigation of the preventive effects of Coenzyme Q10 and Berberine for tourniquet induced ischemia-reperfusion injury on skeletal muscle in rat hindlimb

In this study, the role of CoQ10 and berberine in the treatment of ischemia-reperfusion injury is researched by analyzing the biochemical effects of CoQ10 and berberine administered after experimental ischemia-reperfusion injury in rats. 32 Sprague-Dawley 200-250 g male rats were randomly divided into four equal groups as weighting, including: control, ischemia-reperfusion (I/R) and experimental groups treated with CoQ10 (10 mg/kg dose, 3 times with 8 h intervals) and berberine (200 mg/kg dose, 3 times with 8 h intervals) that were administered by intragastric way to the I/R+ CoQ10 and I/R+ berberine group before two hours ischemia two hours reperfusion with tourniquet. In the sham group, only gastrocnemius muscle were removed and given no CoQ10 and Berberine. By the completion of reperfusion; all rats were anesthetized with ketamine and xylazine, sacrificed after taking samples to measure levels of blood lactate dehydrogenase (LDH), creatine kinase (CK); MDA, MPO, GSH, SOD, GPx and CAT in blood and muscle tissues. Compared to control group, ischemic-reperfusion injury significantly increased plasma LDH, CK; MDA and MPO levels, decreased GSH, SOD, GPx and CAT activities of blood and muscle tissues. Treatments groups showed significantly decreased MDA and MPO levels, increased GSH levels, SOD, GPx and CAT activities compared to the IR group. Our results suggest that CoQ10 and Berberine may protect or treat against oxidative damage on ischemia-reperfusion injury and that can be benefical treating association with lower extremity ischemia-reperfusion injury.

Effect of dexmedetomidine on ischemia-reperfusion injury of liver and kidney tissues in experimental diabetes and hepatic ischemia-reperfusion injury induced rats

Background: Reperfusion following ischemia can lead to more injuries than ischemia itself especially in diabetic patients. The aim of this study was to evaluate the effect of dexmedetomidine on ischemia-reperfusion injury (IRI) in rats with have hepatic IRI and diabetes mellitus.

The effect of pregabalin on tourniquet-induced ischemia-reperfusion injury: a prospective randomized study

Background/aim The aim of this study was to investigate the efficacy of pregabalin on ischemia-reperfusion injuries.Materials and methods Fifty-four patients were randomly assigned into 2 groups. A 150-mg tablet of pregabalin was given the night before and then 1 h before the operation for patients in Group P (pregabalin group, n = 27). A placebo was given to patients in Group C (control group, n = 27) at the same times. After combined spinal-epidural anesthesia was performed, venous blood samples were taken before tourniquet inflation (t1), just before tourniquet deflation (t2), and 20 min after tourniquet deflation (t3) for the analysis of total antioxidant status (TAS), total oxidant status (TOS), catalase (CAT), and ischemia-modified albumin (IMA).Results There was no significant difference in TAS levels between the groups for the t3 period. However, the TAS in Group P was significantly higher in the t3 period than the t2 period (mean ± SD, 0.46 ± 0.1 vs. 0.38 ± 0.2 mmol of Trolox equivalent/L, respectively; P < 0.05). The CAT level in the t3 period was significantly higher in Group P than Group C (mean ± SD, 53.04 ± 32.1 vs. 35.46 ± 17.2 µmol/formaldehyde, respectively; P < 0.05). In the t3 period, the TOS was significantly lower in Group P than Group C (mean ± SD, 11.97 ± 5 vs. 18.29 ± 9.9 pg/mL, respectively; P < 0.05). The TOS in Group P was significantly lower in the t3 period than the t2 period (mean ± SD, 11.97 ± 5 vs. 18.98 ± 10.7 pg/mL, respectively; P < 0.0001).Conclusion Pregabalin has no marked antioxidant activity, but it contributes to the antioxidant defense system of an organism.

The Possible Pathophysiological Outcomes and Mechanisms of Tourniquet-Induced Ischemia-Reperfusion Injury during Total Knee Arthroplasty.

Ischemia and reperfusion (I/R) injury induced by tourniquet (TQ) application leads to the release of both oxygen free radicals and inflammatory cytokines. The skeletal muscle I/R may contribute to local skeletal muscle and remote organ damage affecting outcomes after total knee arthroplasty (TKA). The aim of the study is to summarize the current findings associated with I/R injury following TKA using a thigh TQ, which include cellular alterations and protective therapeutic interventions. The PubMed database was searched using the keywords “ischemia reperfusion injury,” “oxidative stress,” “tourniquet,” and “knee arthroplasty.” The search was limited to research articles published in the English language. Twenty-eight clinical studies were included in this qualitative review. Skeletal muscle I/R reduces protein synthesis, increases protein degradation, and upregulates genes in cell stress pathways. The I/R of the lower extremity elevates local and systemic oxidative stress as well as inflammatory reactions and impairs renal function. Propofol reduces oxidative injury in this I/R model. Ischemic preconditioning (IPC) and vitamin C may prevent oxygen free radical production. However, a high dose of N-acetylcysteine possibly induces kidney injury. In summary, TQ-related I/R during TKA leads to muscle protein metabolism alteration, endothelial dysfunction, oxidative stress, inflammatory response, and renal function disturbance. Propofol, IPC, and vitamin C show protective effects on oxidative and inflammatory markers. However, a relationship between biochemical parameters and postoperative clinical outcomes has not been validated.

Effects of dexmedetomidine on inflammatory mediators after tourniquet-induced ischemia-reperfusion injury: a randomized, double-blinded, controlled study.

Tourniquet use during total knee arthroplasty (TKA) produces ischemia-reperfusion injury (IRI), with systemic release of inflammatory cytokines and reactive oxygen species upon tourniquet release. We conducted a randomized, placebo-controlled, double-blind trial to examine whether dexmedetomidine (DEX) as an adjunct during general anesthesia in patients undergoing unilateral TKA could attenuate the rise in inflammatory cytokines and oxidative stress. Sixty-eight patients were randomized to either the control or DEX group. DEX was administered at a loading dose of 0.5 μg/kg, followed by an infusion of 0.4 μg/kg/h. We measured serum levels of malondialdehyde (biomarker of oxidative stress) and proinflammatory cytokines (interleukin-6 [IL-6] and tumour necrosis factor-α [TNF-α]) preinduction (baseline), 60 and 90 min post-tourniquet release. We also assessed hemodynamics, intraoperative remifentanil consumption, and postoperative pain scores and analgesic consumption. Malondialdehyde was higher than baseline after tourniquet release in both groups (P≤0.001), but the levels were similar between groups at all times. TNF-α was significantly higher than baseline at 60 min post-tourniquet release only in the control group (P=0.009). Serum IL-6 increased significantly above baseline at 60 and 90 min post-tourniquet release in both groups (P<0.001). At 90 min, IL-6 was significantly lower in the dexmedetomidine group than in the control group (P=0.049). Remifentanil consumption, heart rate, and pain scores were significantly lower in the dexmedetomidine group. Our results suggest that dexmedetomidine as an adjunct to general anesthesia attenuated the rise in proinflammatory cytokines, providing protective effects in tourniquet-induced IRI.

Tourniquet-Induced Ischemia-Reperfusion Injury during Total Knee Arthroplasty

Tourniquet-Induced Ischemia-Reperfusion Injury during Total Knee Arthroplasty

The effects of ketamine and lidocaine on free radical production after tourniquet-induced ischemia-reperfusion injury in adults.

The primary aim of this study was to compare the effects of a small-dose infusion of 2 antioxidant agents, ketamine and lidocaine, on ischemia-reperfusion injury (IRI) in patients undergoing elective lower limb surgery. Ischemia-modified albumin (IMA), lactate, and blood gas levels were all measured and assessed. A total of 100 patients who underwent lower extremity surgery were randomized into 3 groups. After spinal anesthesia, the ketamine group (Group K, n=33) was given a ketamine infusion, a lidocaine infusion was administered to the lidocaine group (Group L, n=33), and in the control group (Group C), 0.9% a sodium chloride infusion was performed. Blood samples were obtained for IMA analysis before anesthetic administration (baseline), at 30 minutes of tourniquet inflation (ischemia), and 15 minutes after tourniquet deflation (reperfusion). Arterial blood gas measurements were determined before anesthetic administration and 15 minutes after tourniquet deflation. The lactate and IMA levels at reperfusion were significantly lower in both the ketamine group and the lidocaine group when compared with the control group. The administration of both ketamine and lidocaine infusions significantly decreased skeletal muscle IRI-related high lactate and IMA levels. These results suggest the possibility of the clinical application of ketamine or lidocaine infusions in cases of skeletal muscle-related IRI.

Administration of FTY720 during Tourniquet-Induced Limb Ischemia Reperfusion Injury Attenuates Systemic Inflammation.

Acute ischemia-reperfusion injury (IRI) of the extremities leads to local and systemic inflammatory changes which can hinder limb function and can be life threatening. This study examined whether the administration of the T-cell sequestration agent, FTY720, following hind limb tourniquet-induced skeletal muscle IRI in a rat model would attenuate systemic inflammation and multiple end organ injury. Sprague-Dawley rats were subjected to 1 hr of ischemia via application of a rubber band tourniquet. Animals were randomized to receive an intravenous bolus of either vehicle control or FTY720 15 min after band placement. Rats (n = 10/time point) were euthanized at 6, 24, and 72 hr post-IRI. Peripheral blood as well as lung, liver, kidney, and ischemic muscle tissue was analyzed and compared between groups. FTY720 treatment markedly decreased the number of peripheral blood T cells (p < 0.05) resulting in a decreased systemic inflammatory response and lower serum creatinine levels and had a modest but significant effect in decreasing the transcription of injury-associated target genes in multiple end organs. These findings suggest that early intervention with FTY720 may benefit the treatment of IRI of the limb. Further preclinical studies are necessary to characterize the short-term and long-term beneficial effects of FTY720 following tourniquet-induced IRI.

Tourniquet-induced ischaemia-reperfusion injury: the comparison of antioxidative effects of small-dose propofol and ketamine

ObjectivesThe aim of the present study was to investigate the preventive effects of propofol and ketamine as small dose sedation during spinal anaesthesia on tourniquet-induced ischaemia-reperfusion injury. Methods30 patients were randomly assigned into two groups of 15 patients. In the propofol group, sedation was performed with propofol 0.2mg·kg−1 followed by infusion at a rate of 2mg·kg−1·h−1. In the ketamine group, a continuous infusion of ketamine 0.5mg·kg−1·h−1 was used until the end of surgery. Intravenous administration of midazolam was not used in any patients. Ramsay sedation scale was used for assessing the sedation level. Venous blood samples were obtained before propofol and ketamine infusion (T1), at 30minutes (min) of tourniquet ischaemia (T2), and 5min after tourniquet deflation (T3) for malondialdehyde (MDA) measurements. ResultsNo differences were noted between the groups in haemodynamic (p>0.05) and demographic data (p>0.05). There was no statistically significant difference between the two groups in terms of T1, T2 and T3 periods (p>0.05). There was a statistically increase observed in MDA values respectively both in Group P and Group K between the reperfusion period (1.95±0.59, 2.31±0.48) and pre-ischaemia (1.41±0.38, 1.54±0.45), and ischaemia (1.76±0.70, 1.71±0.38) (μmoL−1) periods (p<0.05). ConclusionsSmall-dose propofol and ketamine has similar potential to reduce the oxidative stress caused by tourniquet-induced ischaemia-reperfusion injury in patients undergoing arthroscopic knee surgery under spinal anaesthesia.

Postischemic conditioning does not reduce muscle injury after tourniquet-induced ischemia-reperfusion injury in rats

BackgroundThe widespread application of tourniquets has reduced battlefield mortality related to extremity exsanguinations. Tourniquet-induced ischemia-reperfusion injury (I/R) can contribute to muscle loss. Postischemic conditioning (PostC) confers protection against I/R in cardiac muscle and skeletal muscle flaps. The objective of this study was to determine the effect of PostC on extremity muscle viability in an established rat hindlimb tourniquet model. MethodsRats were randomly assigned to PostC-1, PostC-2, or no conditioning ischemic groups (n = 10 per group). Postischemic conditioning, performed immediately after tourniquet release, consisted of four 15-second cycles (PostC-1) or eight 15-second cycles (PostC-2) of alternating occlusion and perfusion of hindlimbs. Twenty-four hours later, muscles were excised. The primary end points were muscle edema and viability; secondary end points were histologic and markers of oxidative stress. ResultsIschemia-reperfusion injury decreased viability in all tourniquet limbs, but viability was not improved in either PostC group. Likewise, I/R resulted in substantial muscle edema that was not reduced by PostC. The predominant histologic feature was necrosis, but no significant differences were found among groups. Markers of oxidative stress were increased similarly among groups after I/R, although myeloperoxidase activity was significantly increased only in the no conditioning ischemic group. A protective effect from PostC was not observed in our model suggesting that PostC was not effective in reducing I/R skeletal muscle injury or any benefits of PostC were not sustained for 24 hours when tissues were assessed. ConclusionThese negative findings are pertinent as the military investigates different strategies to extend the safe time for tourniquet application.