Morphological changes in striated muscle during ischaemia. A clinical and histological study in man

A randomized controlled trial: Comparison of one-per-mil tumescent technique and tourniquet in surgery for burn hand contracture in creating clear operative field and assessment of functional outcome

BACKGROUND

This study aims to compare the use of one-per-mil tumescent solution (a mixture of epinephrine and 0.2% lidocaine in a ratio of 1:1,000,000 in normal saline solution) and tourniquet to create clear operative fields and to evaluate the functional outcomes after post burn hand contracture surgery.

METHODS

The subjects of this randomized controlled trial were divided into one-permil tumescent technique and tourniquet group for a similar surgical procedure. Three independent assessors evaluated the clarity of the operative fields through recorded videos for the first 15 min and the first 10-minute of each hour of the surgery. Functional outcome was evaluated at least three months postoperatively using total active and passive motion (TAM and TPM) of each digit. Malondialdehyde (MDA) and tumor necrosis factor alpha (TNF-α) were tested during baseline (5 min before the procedures), ischemia phase, and reperfusion phase (a phase when the blood flow returned to the tissue).

RESULTS

35 subjects were included in this study: 17 in the tumescent group and 18 in the tourniquet group. We found a significant difference in the clarity of operative field between tumescent and tourniquet groups, 5 vs 35 bloodless operative fields, respectively (p < 0.05). TAM and TPM of each digit before surgery and 3 months postoperatively showed no significant difference between both groups (p > 0.05). Furthermore, we found no difference in MDA and TNF-α levels between both groups at their respective phases.

CONCLUSIONS

The use of one-per-mil tumescent technique does not replace tourniquet use to create bloodless operative fields in burned hand contracture surgery. However, the postoperative functional results were similar in both groups showing that tumescent technique can be used as an alternative to tourniquet without compromising outcomes. The MDA and TNF-α examinations do not provide conclusive outcomes regarding ischemia and reperfusion injury.

Acute Limb Ischemia-Much More Than Just a Lack of Oxygen

Acute ischemia of an extremity occurs in several stages, a lack of oxygen being the primary contributor of the event. Although underlying patho-mechanisms are similar, it is important to determine whether it is an acute or chronic event. Healthy tissue does not contain enlarged collaterals, which are formed in chronically malperfused tissue and can maintain a minimum supply despite occlusion. The underlying processes for enhanced collateral blood flow are sprouting vessels from pre-existing vessels (via angiogenesis) and a lumen extension of arterioles (via arteriogenesis). While disturbed flow patterns with associated local low shear stress upregulate angiogenesis promoting genes, elevated shear stress may trigger arteriogenesis due to increased blood volume. In case of an acute ischemia, especially during the reperfusion phase, fluid transfer occurs into the tissue while the vascular bed is simultaneously reduced and no longer reacts to vaso-relaxing factors such as nitric oxide. This process results in an exacerbative cycle, in which increased peripheral resistance leads to an additional lack of oxygen. This whole process is accompanied by an inundation of inflammatory cells, which amplify the inflammatory response by cytokine release. However, an extremity is an individual-specific composition of different tissues, so these processes may vary dramatically between patients. The image is more uniform when broken down to the single cell stage. Because each cell is dependent on energy produced from aerobic respiration, an event of acute hypoxia can be a life-threatening situation. Aerobic processes responsible for yielding adenosine triphosphate (ATP), such as the electron transport chain and oxidative phosphorylation in the mitochondria, suffer first, thus disrupting the integrity of cellular respiration. One consequence of this is irreparable damage of the cell membrane due to an imbalance of electrolytes. The eventual increase in net fluid influx associated with a decrease in intracellular pH is considered an end-stage event. Due to the lack of ATP, individual cell organelles can no longer sustain their activity, thus initiating the cascade pathways of apoptosis via the release of cytokines such as the BCL2 associated X protein (BAX). As ischemia may lead to direct necrosis, inflammatory processes are further aggravated. In the case of reperfusion, the flow of nascent oxygen will cause additional damage to the cell, further initiating apoptosis in additional surrounding cells. In particular, free oxygen radicals are formed, causing severe damage to cell membranes and desoxyribonucleic acid (DNA). However, the increased tissue stress caused by this process may be transient, as radical scavengers may attenuate the damage. Taking the above into final consideration, it is clearly elucidated that acute ischemia and subsequent reperfusion is a process that leads to acute tissue damage combined with end-organ loss of function, a condition that is difficult to counteract.

Law enforcement-applied tourniquets: a case series of life-saving interventions

Although the epidemiology of civilian trauma is distinct from that encountered in combat, in both settings, extremity hemorrhage remains a major preventable cause of potential mortality. The current paper describes the largest case series in the literature in which police officers arriving prior to emergency medical services applied commercially available field tourniquets to civilian victims of violent trauma. Although all 3 patients with vascular injury arrived at the receiving emergency department in extremis, they were successfully resuscitated and survived to discharge without major morbidity. While this outcome is likely multifactorial and highlights the exceptional care delivered by the modern trauma system, tourniquet application appears to have kept critically injured patients alive long enough to reach definitive trauma care. No patient had a tourniquet-related complication. This case series suggests that law enforcement officers can effectively identify indications for tourniquets and rapidly apply such life-saving interventions.

MicroRNA profiling in ischemic injury of the gracilis muscle in rats

Background

To profile the expression of microRNAs (miRNAs) and their potential target genes in the gracilis muscles following ischemic injury in rats by monitoring miRNA and mRNA expression on a genome-wide basis.

Methods

Following 4 h of ischemia and subsequent reperfusion for 4 h of the gracilis muscles, the specimens were analyzed with an Agilent rat miRNA array to detect the expressed miRNAs in the experimental muscles compared to those from the sham-operated controls. Their expressions were subsequently quantified by real-time reverse transcription polymerase chain reaction (real-time RT-PCR) to determine their expression pattern after different durations of ischemia and reperfusion. In addition, the expression of the mRNA in the muscle specimens after 4 h of ischemia and reperfusion for 1, 3, 7, and 14 d were detected with the Agilent Whole Rat Genome 4 × 44 k oligo microarray. A combined approach using a computational prediction algorithm that included miRanda, PicTar, TargetScanS, MirTarget2, RNAhybrid, and the whole genome microarray experiment was performed by monitoring the mRNA:miRNA association to identify potential target genes.

Results

Three miRNAs (miR-21, miR-200c, and miR-205) of 350 tested rat miRNAs were found to have an increased expression in the miRNA array. Real-time RT-PCR demonstrated that, with 2-fold increase after 4 h of ischemia, a maximum 24-fold increase at 7 d, and a 7.5-fold increase at 14 d after reperfusion, only the miR-21, but not the miR-200c or miR-205 was upregulated throughout the experimental time. In monitoring the target genes of miR-21 in the expression array at 1, 3, 7, 14 d after reperfusion, with persistent expression throughout the experiment, we detected the same 4 persistently downregulated target genes (Nqo1, Pdpn, CXCL3, and Rad23b) with the prediction algorithms miRanda and RNAhybrid, but no target gene was revealed with PicTar, TargetScanS, and MirTarget2.

Conclusions

This study revealed 3 upregulated miRNAs in the gracilis muscle following ischemic injury and identified 4 potential target genes of miR-21 by examining miRNAs and mRNAs expression patterns in a time-course fashion using a combined approach with prediction algorithms and a whole genome expression array experiment.

Drop foot after high tibial osteotomy: a prospective study of aetiological factors

Drop foot is not uncommon after high tibial osteotomy for genu varum. The authors report their results of a prospective study of 16 patients operated on between May 1990 and May 1991. All patients had medial femoro-tibial osteoarthritis with a constitutional genu varum. They all had a subtraction valgus high tibial osteotomy fixed by a blade plate. The experimental protocol included clinical review, antero-lateral compartment pressure measurements, intra- and post-operative electromyography, assessment of the post-operative drainage, serum estimation of muscle enzymes and post-operative arteriography. From their own results and a literature review, the authors consider successively the different aetiological factors for post-operative drop foot. Certain deficits occur due to direct trauma on the nerve during high osteotomy of the fibula, by local high pressure due to poor haemostasis or ineffective drainage. In addition, there are several related phenomena. The pneumatic tourniquet sensitises the nerve to trauma, and stretching of the nerve during correction of the deformation depends on the local anatomical factors and their marked variation. In order to diminish the frequency of these post-operative complications, the authors suggest limiting the surgical approach, and limiting as far as possible the traumatic manoeuvres on the nerve by using a tibial resection jig, which allows correction without forced manoeuvres. Finally, the authors discuss the benefits of using a pneumatic tourniquet.

Tourniquets in arterial bypass surgery

BACKGROUND

successful infra-popliteal bypass depends on precise, atraumatic technique in performing the distal anastomosis. The use of a tourniquet facilitates the distal anastomosis, reducing dissection, avoiding traumatising clamping of the vessels and providing an "uncluttered" operating field. Despite these advantages the technique is under-used.

OBJECTIVES

to review the use of tourniquets in arterial reconstruction, with particular reference to safety issues and complications. DESIGN, METHODS AND MATERIALS: a Medline search was performed (last search Feb. 2000), and keywords from relevant papers were used to perform subsequent searches. References were reviewed from each relevant paper.

RESULTS

no randomised controlled trials were found. The review details reported use of tourniquets in arterial reconstruction, including techniques, outcomes and potential complications.

CONCLUSION

the use of a tourniquet is a safe and effective technique to facilitate arterial reconstruction.

Surgical hemostasis by pneumatic ankle tourniquet during 3027 podiatric operations

A retrospective study was performed at the Denver Doctors Hospitals in which 3818 surgical cases on the foot and/or ankle were reviewed over a 4-year period from July 1986 through May 1990. From the 3027 ankle tourniquet cases reviewed, it was determined that pneumatic ankle tourniquets are safe and effective in providing hemostasis during foot surgery. There were five postoperative complications noted with ankle cuffs, with post-tourniquet syndrome being the most common (three cases). Over the 4-year period, ankle tourniquets failed a total of 50 times, a 1.8% failure rate (0.25% failure rate in the last 17 months). The most common pressure setting used for ankle cuffs was 325 mm. Hg (400 mm. Hg for thigh cuffs). Tourniquet ischemia lasted from 4 to 139 min.; the most common duration of ischemia noted for ankle tourniquets was 30 to 60 min. (60 to 90 min. for thigh tourniquets). A review of the potential complications associated with tourniquets, as well as safeguards, recommendations, and contraindications are presented.

Compartment syndrome. A complication of intravenous regional anesthesia in the reduction of lower leg shaft fractures

Forty-one consecutive patients who had closed reduction of closed lower leg shaft fractures under an intravenous regional anesthetic are reviewed for the complication of compartment syndrome. Four patients were graded as having mild compartment syndrome, two as moderate, and five as severe, giving an overall rate of 27%. This was compared with a control group of 39 consecutive patients who also underwent closed reduction of closed lower leg shaft fractures, but under general anesthesia or intravenous analgesia alone rather than an intravenous regional anesthetic. In the control group, three patients were graded as having mild compartment syndrome, and two as severe, giving an overall complication rate of 13%. The authors feel that the use of the thigh tourniquet with the intravenous regional anesthetic technique increases the frequency of compartment syndrome as a complication in lower leg fractures.

Isolated contracture of the abductor digiti minimi

A case of isolated contracture of an intrinsic hand muscle, the abductor digiti minimi, after the use of an upper extremity tourniquet is reported. Six cadaver specimens were studied after latex arterial injection. We present an anatomic study and pathomechanical analysis, along with a review of the literature on tourniquet-associated injuries.

Local compression patterns beneath pneumatic tourniquets applied to arms and thighs of human cadavera

Distributions of tissue fluid pressure were examined beneath a standard pneumatic tourniquet in six upper extremities and six lower extremities of fresh human cadavera, disarticulated at the shoulder and hip, respectively. A standard 8-cm-wide tourniquet cuff was applied at mid-humerus or mid-femur position. Tissue fluid pressures were measured by 100-cm-long slit catheters inserted parallel to the bone at four tissue depths: subcutaneous, subfascial, mid-muscle, and adjacent to bone. All arms and thighs were studied at the following cuff pressures: 100, 150, 200, 250, 300, 400, and 500 mm Hg. Tissue fluid pressure was always maximal in subcutaneous tissue at mid-cuff. Transmission of cuff pressures to deeper tissues was significantly less (p less than 0.01) in the thighs with a girth of 40-52 cm than in the arms with a girth of 22-33 cm. At the four tissue depths studied, tissue fluid pressures fell steeply in a longitudinal direction near the cuff edge to levels near zero at points 1-2 cm outside each cuff edge. Our results suggest that wider cuffs are required on thighs than on arms to provide a bloodless field during limb surgery and to minimize underlying tissue injury associated with high cuff pressures. Our recommendation for wider tourniquet cuffs than those presently used during orthopaedic surgery is contrary to recent prevailing knowledge.

Energy metabolism and histomorphological findings in replanted rat hind limbs using various conservation methods

Using various storage and conservation methods, we examined amputated and subsequently replanted limbs for their ischaemia tolerance level by investigating the changes in the adenylphosphocreatine system and glycolysis cycle. After replantation, amputated limbs that had been stored at room temperature (21.0 +/- 1.5 degrees C) for 2 hours were examined 14 days after operation. The adenosine triphosphate level of the skeletal muscle was reduced to 51% and the creatine phosphate to 77% of that of the control group. The glycogen was 13% of the normal value. The biochemical findings correlate with the histomorphological findings. After 2 hours ischaemia, the cross striations of the skeletal muscle and nuclear staining remained intact. There is a breakdown of the biochemical systems after 4 hours of ischaemia. They are no longer intact and the ischaemic limb does not recover. Histologically, muscle necrosis can be observed.

Patency of anastomosed arteries and veins subjected to reapplication of microvascular clamps

One hundred and two rat femoral vessels, both vein and artery, were transected and repaired with a standard technique. After a 30-minute observation period, vessel clamps were reapplied in a standardized manner. The repairs were reexplored at 2 weeks. The results demonstrated no serious reduction in vessel patency in the first period or at the 2 week exploration. Reapplication of vessel clamps after an initial flow period post anastomosis does not have a significant effect on vessel patency.

Early histopathologic changes in experimentally replanted extremities

Early serial histologic changes in replanted extremities have not been well defined; their contribution to a suboptimal functional result is unknown. With the use of a rat hind limb replantation model to address this question, we studied tissues of the replanted legs by light microscopy from 1 to 60 days after replantation. Although early lesions were consistent with ischemic injury, the chronic preparations were remarkably normal, and the lesions were more consistent with denervation. Poor function in clinical replantations may be a reflection of more pronounced versions of these pathologic lesions.

Effect of tourniquet ischaemia on muscle energy metabolism in meniscectomy patients

The enzyme levels of muscle energy metabolism were studied in eight male meniscectomy patients before and 10 minutes after release of the tourniquet and on the third post-operative day. The average tourniquet time was 65.1 min. The muscle samples were taken from the vastus lateralis muscles; the healthy side served as the control. The greatest enzyme changes 10 min after release of the tourniquet were the falls in succinate dehydrogenase (SDH) and creatine phosphokinase (CPK) activities, (p less than 0.01 and p less than 0.025 respectively). On the 3rd day phosphofructokinase (FFK) and malate dehydrokinase (MDH) activities were also lowered in the tourniquet limb, but the lactate dehydrogenase (LDH) was not changed significantly. In the control extremity only SDH showed a lowered value on the 3rd post-operative day (p less than 0.05), perhaps due to hypokinesia in hospital. The results indicate that even one-hour tourniquet ischaemia causes an enzyme release from muscle and for at least three days after the tourniquet enzyme activities in muscle are lowered, perhaps because of the combined effect of the tourniquet ischaemia and hypokinesia after the operation.

The effect of tourniquet ischaemia on intact, tenotomized and motor nerve injured human hand muscles

Ultrastructural examination of the intrinsic hand muscles was performed on young healthy patients undergoing reconstructive operation following tendon or nerve lesions. The muscle specimens were taken at the start and then every fifteen to twenty minutes until the end of the tourniquet ischaemia. The authors have not found any morphological alterations following the use of a tourniquet up to two hours in either the intact or previously injured muscles.

Morphological and biochemical changes in striated muscle after experimental tourniquet ischaemia

Histological and biochemical changes were studied in the striated muscle following total tourniquet ischaemia between one and four h, the reflow time being 30 min and 24 h. Electronmicroscopy was applied to study the fine structure of the muscle after 24 h reflow. In light microscopy ischaemic changes were not seen even when the tourniquet time was extended to four h. When a four-h ischaemia was followed by a 24-h recovery period, the electron microscopy showed a variety of minor mitochondrial changes such as condensed and slightly dilatated mitochondria. The SDH activities did not vary significantly between the experimental and control samples even after a four-h ischaemia followed by 30 min or 24h reflow. The differences between the experimental and control samples were, however, highly significant in the LDH values in the groups where ischaemia had lasted for three and four h. The results indicate that tourniquet ischaemia for two to three h does not significantly affect the striated muscle of a rabbit and the alterations even after a four-h ischaemia seem to be partly reversible.

Systemic reactions to tourniquet ischaemia

In 15 patients, mean age 60 years, undergoing knee arthroplasty under lumbar epidural analgesia, changes in ECG, blood pressure, blood gases, serum potassium, acid-base status and serum creatine-phosphokinase were studied following release of a tourniquet applied for 70-135 min. During and after the ischaemia, the skin temperature of the leg operated on was monitored. Although dextran-70 was rapidly infused following tourniquet release, the blood pressure decreased significantly, due to a reduction in peripheral resistance. There were no signs of myocardial or pulmonary disturbances. Serum potassium in arterial blood increased significantly and reached a peak 3 min after tourniquet release. There was a tendency to metabolic acidosis, most pronounced after 3 min and caused by local lactate production. The skin temperature of the ischaemic leg fell progressively, which, combined with muscular relaxation, indicates a low metabolic rate. There was no evidence of local ischaemic muscular injury. It is concluded that the systemic changes after interruption of up to 2 h of tourniquet ischaemia are moderate and reversible, even in the elderly.

The tourniquet

The morbidity of the tourniquet is not well documented. The "post-tourniquet syndrome" is the most common side effect, but is usually unrecognized. The causation of nerve palsy, although this sequela is uncommon, has been documented. Other problems associated with tourniquet use are discussed.

The acute effects of tourniquet ischemia on tissue and blood gas tensions in the primate limb

Tourniquet ischemia results in tissue hypoxia which has been measured indirectly by blood gas analysis. The Medspect mass spectrometer allows direct measurement of gas tension in different tissues and may provide more useful information regarding safe tourniquet times. Calibrated Teflon catheters were inserted into the subcutaneous tissue (11 animals), tibial medullary cavities (bone) (nine animals), and tibialis anterior muscles (10 animals) in both lower extremities of anesthetized stumptail monkeys. Tourniquet ischemia was maintained for 1 hour at 400 mm Hg. Tissue and venous blood gas tensions were recorded from both limbs for 1 1/2 hours. Comparisons between gas tensions in each tissue group were made on the basis of their percentage change from control values. In the ischemic limb within 5 minutes muscle PO2 fell 42 +/- 4% (p is less than 0.001), whereas bone and subcutaneous PO2 dropped 25 +/- 4% (p is less than 0.05). Blood PO2 fell 29 +/- 3% and differed only from that of muscle (p is less than 0.01). One hour after tourniquet inflation, blood PO2 levels has fallen 90 +/- 5% (p is less than 0.001) from their control. Changes in tissue PCO2 were less dramatic and did not vary significantly from those recorded in venous blood. After deflation, blood PO2 exceeded its control by 20 +/- 6% (p is less than 0.005) in 5 minutes, but tissue tensions remained 50 +/- 6% below their control values. These studies indicate that tissue gas tensions are a more sensitive indicator of tourniquet hypoxia than are blood gases within the ischemic extremity.

Tourniquet ischemia: ultrastructural and histochemical observations of ischemic human muscle and of monkey muscle and nerve

Biopsies of muscle from ten patients and of muscle and nerve from three monkeys were obtained during periods of continuous ischemia and studied by light and electron microscopy and by histochemical means. Between the third and fourth hours of ischemia, swelling of the mitochondria was noted in monkey muscle. One week later the appearance was normal. In the monkey nerves degenerated myelin was seen one week later but appeared to be normal at 2 weeks. If after 3 hours the tourniquet was deflated for 30 minutes and then reapplied for 2 additional hours, no changes were found. Succinic dehyrogenase analysis was used to identify swelling of the mitochondria. No mitochondrial changes were seen in human muscle made ischemic by a tourniquet for 2 hours.

The risk of deep-vein thrombosis after operations on a bloodless lower limb. A venographic study

In 17% of 40 patients undergoing operation in a bloodless field on the lower limb, thrombosis was diagnosed phlebographically. Phlebography was performed between the second and eighth postoperative day. The incidence of thrombosis in this series was relatively low, considering other reports on postoperative thrombosis and the theoretical dangers of thrombosis involved in the use of a tourniquet. Factors which could explain the relatively low frequency of postoperative thrombosis are discussed.

Human skeletal muscle energy metabolism during and after complete tourniquet ischemia

The extent of cellular metabolic deterioration and its reversibility was studied on human skeletal muscle needle biopsies during operations in bloodless field. The tissue levels of high energy phosphates and glycolytic metabolites were analyzed after various times of tourniquet ischemia and compared to contralateral control extremity levels. In the ischemic extremity the phosphocreatine (CrP) levels decreased by 40% within 30-60 min and after 60-90 min a 60% reduction was found. No significant ATP changes occurred. Lactate levels increased by 225% after 30-60 min and by 300% after 60-90 min. The glucose and G-6-P levels increased slightly and indicated glycogenolysis. The rate of the metabolic changes decreased with ischemia time. In the control leg no significant metabolic changes could be seen. After the release of the tourniquet there was a rapid restoration of the phosphagen content and clearance of lactate in the ischemic leg. Near control levels of these substances were seen already after 5 min. The present results show that clinical tourniquet ischemia of up to 90 min duration produces less pronounced metabolic alterations than those seen in working muscle.