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Available hind limb IR animal model are either artery vein ligation or tourniquet application (by rubber band or O-ring).
Possible treatments are the application of IR related-pathway derived drug/inhibitor and cell therapy. The study has been done a role for p53 in activating necrosis. During oxidative stress, p53 accumulates in the mitochondrial matrix and triggers mitochondrial permeability transition pore (PTP) opening. To the end of this, necrosis occurs by physical interaction with the PTP regulator cyclophilin D (CypD). The mitochondrial p53-CypD axis as an important contributor to oxidative stress-induced necrosis and implicates in disease pathology and possible treatment. Cyclosporine A, known as a potent the mitochondrial permeability transition pore (mPTP) opening inhibitor and extremely powerful in protecting cardiomyocytes from IR, normalized ROS production, decreased inflammation, and restored mitochondrial coupling during aortic cross-clamping in Rat hind limb IR model.
There are some preliminary studies that seem to indicate that treatment with hydrogen sulfide (HS) can have a protective effect against reperfusion injury.
Pneumatic, surgical tourniquets are frequently applied in the controlled environment of the operating room in order to control blood loss during an upper or lower extremity operative case. Aside from lower blood loss in itself, this improves visualization and surgical efficiency. Modern examples are found in many different sizes to accommodate different patients and sites of applications, with adult cuffs approximately 4" wide. This distributes the pressure over, generally, a broader area than field (emergency, combat) tourniquets. The cuff is typically attached to an adjustable pneumatic pump with a built-in timer. Surgical tourniquet times in excess of 2 hours have been associated with an increased risk of nerve damage (e.g., neuropraxia), likely related to both direct nerve compression as well as decreased arterial inflow and oxygenation. The ischemia-reperfusion injury associated with surgical tourniquets is typically not clinically apparent when used for less than 2 hours.
Emergency field tourniquets have been used for many centuries, and have seen a resurgence in the recent combat operations in Afghanistan and Iraq, as well as expanded use in civilian trauma and mass casualty settings. Expedient and widespread tourniquet use in the modern combat setting is frequently cited as a primary driver for increased survival following major battlefield trauma. These tourniquets are often 1-2" in width, which concentrates the pressure to a narrow band of tissue. They can result in tissue necrosis if kept in place for long periods, and should only be applied after other methods to control bleeding (e.g., elevation or direct pressure to the wound) have failed, except in settings where time does not allow waiting. Generally, tissue distal to a field tourniquet that has been in place for greater than 6 hours is considered likely to be non-viable.
In the same way that external compression tourniquets reduce or eliminate arterial blood flow, aortic cross clamping has the same effect. The Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) device achieves this as well. By design, these devices induce ischemia to the lower extremities (as a secondary effect, or less commonly as their primary use). Releasing the cross clamp or removing the REBOA initiates reperfusion, and IR injury to the lower extremities may follow.
A study of aortic cross-clamping, a common procedure in cardiac surgery, demonstrated a strong potential benefit with further research ongoing.
Early treatment is essential to keep the affected limb viable. The treatment options include injection of an anticoagulant, thrombolysis, embolectomy, surgical revascularisation, or amputation. Anticoagulant therapy is initiated to prevent further enlargement of the thrombus. Continuous IV unfractionated heparin has been the traditional agent of choice.
If the condition of the ischemic limb is stabilized with anticoagulation, recently formed emboli may be treated with catheter-directed thrombolysis using intraarterial infusion of a thrombolytic agent (e.g., recombinant tissue plasminogen activator (tPA), streptokinase, or urokinase). A percutaneous catheter inserted into the femoral artery and threaded to the site of the clot is used to infuse the drug. Unlike anticoagulants, thrombolytic agents work directly to resolve the clot over a period of 24 to 48 hours.
Direct arteriotomy may be necessary to remove the clot. Surgical revascularization may be used in the setting of trauma (e.g., laceration of the artery). Amputation is reserved for cases where limb salvage is not possible. If the patient continues to have a risk of further embolization from some persistent source, such as chronic atrial fibrillation, treatment includes long-term oral anticoagulation to prevent further acute arterial ischemic episodes.
Decrease in body temperature reduces the aerobic metabolic rate of the affected cells, reducing the immediate effects of hypoxia. Reduction of body temperature also reduces the inflammation response and reperfusion injury. For frostbite injuries, limiting thawing and warming of tissues until warmer temperatures can be sustained may reduce reperfusion injury.
Oxygen consumption of skeletal muscle is approximately 50 times larger while contracting than in the resting state. Thus, resting the affected limb should delay onset of infarction substantially after arterial occlusion.
Low molecular weight heparin is used to reduce or at least prevent enlargement of a thrombus, and is also indicated before any surgery. In the legs, below the inguinal ligament, percutaneous aspiration thrombectomy is a rapid and effective way of removing thromboembolic occlusions. Balloon thrombectomy using a Fogarty catheter may also be used. In the arms, balloon thrombectomy is an effective treatment for thromboemboli as well. However, local thrombi from atherosclerotic plaque are harder to treat than embolized ones. If results are not satisfying, another angiography should be performed.
Thrombolysis using analogs of tissue plasminogen activator (tPA) may be used as an alternative or complement to surgery. Where there is extensive vascular damage, bypass surgery of the vessels may be necessary to establish other ways to supply the affected parts.
Swelling of the limb may cause inhibited flow by increased pressure, and in the legs (but very rarely in the arms), this may indicate a fasciotomy, opening up all four leg compartments.
Because of the high recurrence rates of thromboembolism, it is necessary to administer anticoagulant therapy as well. Aspirin and low molecular weight heparin should be administered, and possibly warfarin as well. Follow-up includes checking peripheral pulses and the arm-leg blood pressure gradient.
The clinician must protect the patient against hypotension, renal failure, acidosis, hyperkalemia and hypocalcemia. Admission to an intensive care unit, preferably one experienced in trauma medicine, may be appropriate; even well-seeming patients need observation. Treat open wounds as surgically appropriate, with debridement, antibiotics and tetanus toxoid; apply ice to injured areas.
Intravenous hydration of up to 1.5 L/hour should continue to prevent hypotension. A urinary output of at least 300 ml/hour should be maintained with IV fluids and mannitol, and hemodialysis considered if this amount of diuresis is not achieved. Use intravenous sodium bicarbonate to keep the urine pH at 6.5 or greater, to prevent myoglobin and uric acid deposition in kidneys.
To prevent hyperkalemia/hypocalcemia, consider the following adult doses:
- calcium gluconate 10% 10ml or calcium chloride 10% 5 ml IV over 2 minutes
- sodium bicarbonate 1 meq/kg IV slow push
- regular insulin 5–10 U
- 50% glucose 1–2 ampules IV bolus
- kayexalate 25–50 g with sorbitol 20% 100 ml by mouth or rectum.
Even so, cardiac arrhythmias may develop; electrocardiographic monitoring is advised, and specific treatment begun promptly.
The main goals of treatment in distributive shock are to reverse the underlying cause and achieve hemodynamic stabilization. Immediate treatment involves fluid resuscitation and the use of vasoactive drugs, both vasopressors and inotropes. Hydrocortisone is used for patients whose hypotension does not respond to fluid resuscitation and vasopressors. Opening and keeping open the microcirculation is a consideration in the treatment of distributive shock, as a result limiting the use of vasopressors has been suggested. Control of inflammation, vascular function and coagulation to correct pathological differences in blood flow and microvascular shunting has been pointed to as a potentially important adjunct goal in the treatment of distributive shock.
Patients with septic shock are treated with antimicrobial drugs to treat the causative infection. Some sources of infection require surgical intervention including necrotizing fasciitis, cholangitis, abscess, intestinal ischemia, or infected medical devices.
Anaphylactic shock is treated with epinephrine.
Chronic compartment syndrome in the lower leg can be treated conservatively or surgically. Conservative treatment includes rest, anti-inflammatories, and manual decompression. Elevation of the affected limb in patients with compartment syndrome is contraindicated, as this leads to decreased vascular perfusion of the affected region. Ideally, the affected limb should be positioned at the level of the heart. The use of devices that apply external pressure to the area, such as splints, casts, and tight wound dressings, should be avoided. If symptoms persist after conservative treatment or if an individual does not wish to cease engaging in the physical activities which bring on symptoms, compartment syndrome can be treated by a surgery known as a fasciotomy. Surgery is the most effective treatment for compartment syndrome. Incisions are made in the affected muscle compartments so that they will decompress. This decompression will relieve the pressure on the venules and lymphatic vessels, and will increase bloodflow throughout the muscle. Left untreated, chronic compartment syndrome can develop into the acute syndrome and lead to permanent muscle and nerve damage.
A military study conducted in 2012 found that teaching individuals with lower leg chronic exertional compartment syndrome to change their running stride to a forefoot running technique abated symptoms. Follow up studies are needed to confirm the finding of this study.
Hyperbaric oxygen therapy has been suggested by case reports – though as of 2011 not proven in controlled randomized trials – to be an effective adjunctive therapy for crush injury, compartment syndrome, and other acute traumatic ischemias, by improving wound healing and reducing the need for repetitive surgery.
The treatment of mesenteric ischemia depends on the cause, and can be medical or surgical. However, if bowel has become necrotic, the only treatment is surgical removal of the dead segments of bowel.
In non-occlusive mesenteric ischemia, where there is no blockage of the arteries supplying the bowel, the treatment is medical rather than surgical. People are admitted to the hospital for resuscitation with intravenous fluids, careful monitoring of laboratory tests, and optimization of their cardiovascular function. NG tube decompression and heparin anticoagulation may also be used to limit stress on the bowel and optimize perfusion, respectively.
Surgical revascularisation remains the treatment of choice for mesenteric ischaemia related to an occlusion of the vessels supplying the bowel, but thrombolytic medical treatment and vascular interventional radiological techniques have a growing role.
If the ischemia has progressed to the point that the affected intestinal segments are gangrenous, a bowel resection of those segments is called for. Often, obviously dead segments are removed at the first operation, and a second-look operation is planned to assess segments that are borderline that may be savable after revascularization.
Acute compartment syndrome is a medical emergency requiring immediate surgical treatment, known as a fasciotomy, to allow the pressure to return to normal. Although only one compartment is affected, fasciotomy is done to release all compartments. For instance, if only the deep posterior compartment of a leg is affected, the treatment would be fasciotomy (with medial and lateral incisions) to release all compartments of the leg in question, namely the anterior, lateral, superficial posterior and deep posterior.
An acute compartment syndrome has some distinct features such as swelling of the compartment due to inflammation and venous occlusion. Decompression of the nerve traversing the compartment might alleviate the symptoms (Rorabeck, 1984). Until definitive fasciotomy can be performed, the extremity should be placed at the level of the heart. Hypotension should also be avoided, as this decreases perfusion pressure to the compartment. Supplemental oxygen also optimizes tissue and neural oxygenation.
As mentioned, permissive hypotension is unwise. Especially if the crushing weight is on the patient more than 4 hours, but often if it persists more than one hour, careful fluid overload is wise, as well as the administration of intravenous sodium bicarbonate. The San Francisco emergency services protocol calls for a basic adult dose of a 2 L bolus of normal saline followed by 500 ml/h, limited for "pediatric patients and patients with history of cardiac or renal dysfunction."
If the patient cannot be fluid loaded, this may be an indication for a tourniquet to be applied.
When someone presents with an ischemic event, treatment of the underlying cause is critical for prevention of further episodes.
Anticoagulation with warfarin or heparin may be used if the patient has atrial fibrillation.
Operative procedures such as carotid endarterectomy and carotid stenting may be performed if the patient has a significant amount of plaque in the carotid arteries associated with the local ischemic events.
Intracerebral hemorrhages is a severe condition requiring prompt medical attention. Treatment goals include lifesaving interventions, supportive measures, and control of symptoms. Treatment depends on the location, extent, and cause of the bleeding. Often, treatment can reverse the damage that has been done.
A craniotomy is sometimes done to remove blood, abnormal blood vessels, or a tumor. Medications may be used to reduce swelling, prevent seizures, lower blood pressure, and control pain.
The first line of treatment is often to treat the patients pain with neuropathic drugs such as tricyclic antidepressants, serotonin reuptake inhibitors, and anticonvulsants. The second lines of drugs to treat pain are non-steroidal anti-inflammatories, tramadol, and opioids. Other techniques used to facilitate healing of the nerve and pain are either static or dynamic splinting that can both help protect the injured part as well as improve function. Sometimes surgery is an option, although the prognosis is still very poor of regaining function of the affected nerve. The goal of surgery is to join healthy nerve to unhealthy nerve. The most common surgical techniques include external neurolysis, end-to-end repair, nerve grafting, and nerve transfer from somewhere else in the body.
Alteplase (tpa) is an effective medication for acute ischemic stroke. When given within 3 hours, treatment with tpa significantly improves the probability of a favourable outcome versus treatment with placebo.
The outcome of brain ischemia is influenced by the quality of subsequent supportive care. Systemic blood pressure (or slightly above) should be maintained so that cerebral blood flow is restored. Also, hypoxaemia and hypercapnia should be avoided. Seizures can induce more damage; accordingly, anticonvulsants should be prescribed and should a seizure occur, aggressive treatment should be undertaken. Hyperglycaemia should also be avoided during brain ischemia.
Treatment approaches can include osmotherapy using mannitol, diuretics to decrease fluid volume, corticosteroids to suppress the immune system, hypertonic saline, and surgical decompression to allow the brain tissue room to swell without compressive injury.
The fact that the ischemic cascade involves a number of steps has led doctors to suspect that neuroprotectants such as calcium channel blockers or glutamate antagonists could be produced to interrupt the cascade at a single one of the steps, blocking the downstream effects. Though initial trials for such neuroprotective drugs led many to be hopeful, until recently, human clinical trials with neuroprotectants such as NMDA receptor antagonists were unsuccessful.
On October 7, 2003, a U.S. patent number 6630507 entitled "Cannabinoids as Antioxidants and Neuroprotectants" was awarded to the United States Department of Health and Human Services, based on research carried out at the National Institute of Mental Health (NIMH), and the National Institute of Neurological Disorders and Stroke (NINDS). This patent claims that cannabinoids are "useful in the treatment and prophylaxis of wide variety of oxidation associated diseases such as ischemia, inflammatory ... and autoimmune diseases. The cannabinoids are found to have particular application as neuroprotectants, for example in limiting neurological damage following ischemic insults, such as stroke and trauma..."
On November 17, 2011, in accordance with 35 U.S.C. 209(c)(1) and 37 CFR part 404.7(a)(1)(i), the National Institutes of Health, Department of Health and Human Services, published in the Federal Register, that it is contemplating the grant of an exclusive patent license to practice the invention embodied in U.S. Patent 6,630,507, entitled “Cannabinoids as antioxidants and neuroprotectants” and PCT Application Serial No. PCT/US99/08769 and foreign equivalents thereof, entitled “Cannabinoids as antioxidants and neuroprotectants” [HHS Ref. No. E-287-1997/2] to KannaLife Sciences Inc., which has offices in New York, U.S. This patent and its foreign counterparts have been assigned to the Government of the United States of America. The prospective exclusive license territory may be worldwide, and the field of use may be limited to: The development and sale of cannabinoid(s) and cannabidiol(s) based therapeutics as antioxidants and neuroprotectants for use and delivery in humans, for the treatment of hepatic encephalopathy, as claimed in the Licensed Patent Rights.
With treatment, approximately 80% of patients are alive (approx. 95% after surgery) and approximately 70% of infarcted limbs remain vital after 6 months.
Septic shock is associated with significant mortality and is the leading non cardiac cause of death in intensive care units (ICUs).
Management involves general measures to stabilize the person while also using specific investigations and treatments. These include the prevention of rebleeding by obliterating the bleeding source, prevention of a phenomenon known as vasospasm, and prevention and treatment of complications.
Stabilizing the person is the first priority. Those with a depressed level of consciousness may need to be intubated and mechanically ventilated. Blood pressure, pulse, respiratory rate, and Glasgow Coma Scale are monitored frequently. Once the diagnosis is confirmed, admission to an intensive care unit may be preferable, especially since 15 percent may have further bleeding soon after admission. Nutrition is an early priority, with by mouth or nasogastric tube feeding being preferable over parenteral routes. In general, pain control is restricted to less-sedating agents such as codeine, as sedation may impact on the mental status and thus interfere with the ability to monitor the level of consciousness. Deep vein thrombosis is prevented with compression stockings, intermittent pneumatic compression of the calves, or both. A bladder catheter is usually inserted to monitor fluid balance. Benzodiazepines may be administered to help relieve distress. Antiemetic drugs should be given to awake persons.
People with poor clinical grade on admission, acute neurologic deterioration, or progressive enlargement of ventricles on CT scan are, in general, indications for the placement of an external ventricular drain by a neurosurgeon. The external ventricular drain may be inserted at the bedside or in the operating room. In either case, strict aseptic technique must be maintained during insertion. In people with aneurysmal subarachnoid hemorrhage the EVD is used to remove cerebrospinal fluid, blood, and blood byproducts that increase intracranial pressure and may increase the risk for cerebral vasospasm.
Warfarin and vitamin K antagonists are anticoagulants that can be taken orally to reduce thromboembolic occurrence. Where a more effective response is required, heparin can be given (by injection) concomitantly. As a side effect of any anticoagulant, the risk of bleeding is increased, so the international normalized ratio of blood is monitored. Self-monitoring and self-management are safe options for competent patients, though their practice varies. In Germany, about 20% of patients were self-managed while only 1% of U.S. patients did home self-testing (according to one 2012 study). Other medications such as direct thrombin inhibitors and direct Xa inhibitors are increasingly being used instead of warfarin.
Schwann cells provide the nerve with protection through the production of Nerve Growth Factors, and because these cells are intact this kind of nerve injury can be cured and normal feeling and sensations can be restored. Surgery can be done in order to help the nerve heal. The surgery will help with nerve regeneration, providing guidance to the nerve sprouts on where to attach on the proximal side of the injury. Damaged nerve axons can reattach themselves after surgery. Treatment of axonotmesis also consists of:
- Physical therapy or Occupational Therapy. Physical or Occupational therapy aims include:
- Pain relief
- Maintain range of motion
- Reducing muscular atrophy
- Patient education
- Use of assistive devices (Orthotic needs)
Vasospasm, in which the blood vessels constrict and thus restrict blood flow, is a serious complication of SAH. It can cause ischemic brain injury (referred to as "delayed ischemia") and permanent brain damage due to lack of oxygen in parts of the brain. It can be fatal if severe. Delayed ischemia is characterized by new neurological symptoms, and can be confirmed by transcranial doppler or cerebral angiography. About one third of people admitted with subarachnoid hemorrhage will have delayed ischemia, and half of those have permanent damage as a result. It is possible to screen for the development of vasospasm with transcranial Doppler every 24–48 hours. A blood flow velocity of more than 120 centimeters per second is suggestive of vasospasm.
The use of calcium channel blockers, thought to be able to prevent the spasm of blood vessels by preventing calcium from entering smooth muscle cells, has been proposed for prevention. The calcium channel blocker nimodipine when taken by mouth improves outcome if given between the fourth and twenty-first day after the bleeding, even if it does not reduce the amount of vasospasm detected on angiography. It is the only Food and Drug Administration (FDA) approved drug for treating cerebral vasospasm. In "traumatic" subarachnoid hemorrhage, nimodipine does not affect long-term outcome, and is not recommended. Other calcium channel blockers and magnesium sulfate have been studied, but are not presently recommended; neither is there any evidence that shows benefit if nimodipine is given intravenously.
Some older studies have suggested that statin therapy might reduce vasospasm, but a subsequent meta-analysis including further trials did not demonstrate benefit on either vasospasm or outcomes. While corticosteroids with mineralocorticoid activity may help prevent vasospasm their use does not appear to change outcomes.
A protocol referred to as "triple H" is often used as a measure to treat vasospasm when it causes symptoms; this is the use of intravenous fluids to achieve a state of hypertension (high blood pressure), hypervolemia (excess fluid in the circulation), and hemodilution (mild dilution of the blood). Evidence for this approach is inconclusive; no randomized controlled trials have been undertaken to demonstrate its effect.
If the symptoms of delayed ischemia do not improve with medical treatment, angiography may be attempted to identify the sites of vasospasms and administer vasodilator medication (drugs that relax the blood vessel wall) directly into the artery. Angioplasty (opening the constricted area with a balloon) may also be performed.
Thrombolysis is the pharmacological destruction of blood clots by administering thrombolytic drugs including recombitant tissue plasminogen activator, which enhances the normal destruction of blood clots by the body's enzymes. This carries an increased risk of bleeding so is generally only used for specific situations (such as severe stroke or a massive pulmonary embolism).