Musculoskeletal Flashcards
What are the two theories regarding the pathophysiology of compartment syndrome
Arteriovenous pressure gradient theory, Ischemia-reperfusion syndrome theory
Explain the arteriovenous pressure gradient theory in compartment syndrome
increased pressure within the tissue leads to increased pressure of the veins in the compartment, this causes a decrease in the arteriovenous pressure gradient (reduced arterial pressure, increased venous pressure) within the compartment. The decrease in pressure gradient results in decreased oxygen delivery. Inadequate venous drainage further increases pressure -> ischemia of the affected organs or tissue within the compartment
compartment pressures capable of compromising perfusion develop when they rise to within 10 to 30 mmHg of diastolic pressure; muscle oxygenation decreases as tissue pressure approaches mean arterial pressure. Therefore, acute extremity compartment syndrome develops based on both compartment and systemic blood pressures. As an example, compared with a normotensive patient, a patient with hypotension is less likely to tolerate any given increase in tissue pressure.
Explain the ischemia-reperfusion syndrome theory in compartment syndrome
As the pressure within the individual compartments increases, the interstitial fluid pressure will rise above the capillary pressure, and when this happens there is an inability to perfuse the organs or tissue within that compartment (ischemia). Following a period when perfusion is impaired, the ensuing reperfusion causes a massive production of reactive oxygen species (ROS) in addition to the decreased oxygen delivery. A vicious cycle of hypoxia, anaerobic metabolism, further vasoconstriction, and continued cellular damage ensues.
What is primary and secondary compartment syndrome
Primary due to injury or disease proves within that compartment
Secondary due to injury or disease outside that compartment
Clinical signs of skeletal muscle compartment syndrome
Pain of the limb, palpable tenseness, paraesthesia or paresis of the limb, pulselessness of the limb
How do you get a definite diagnosis of skeletal compartment syndrome
insert needle into compartment and use manometer to measure pressure
near-infrared spectroscopy
what is normal intrabdominal pressure in the dog and in the cat and when should you treat
normal intraabdominal pressure dogs 1.5-5.1 mmHg
normal intraabdominal pressure cats 3.8-6.5 mmHg
pressures > 10 cm H2O be considered mild elevations in IAP. I treat when IAP > 20 cm H2O in dogs and cats
what is the definition of abdominal compartment syndrome
defined as a sustained or repeated pathological elevation in intraabdominal pressure ≥ 12 mm Hg
give 3 systemic affects of intraabdominal hypertension and abdominal compartment syndrome
cardiovascular: compression of the vena cava resulting in decreased left ventricular filling and decreased cardiac output. Decreased left ventricular compliance because of a secondary rise in intrathoracic pressure. Direct myocardial ischemia
cns: increased intracranial pressure secondary to combination of decreased cardiac output and obstruction of cerebral venous outflow causing decreased cerebral perfusion pressure
renal: increased pressure in the abdomen resulting in compression of the urinary collecting ducts and renal vessels, leading to oligura
lymphatics: decreased to absent mesenteric lymph flow secondary to compression from the increased abdominal pressure
pulmonary: decreased diaphragmatic excursion secondary to compression from the abdomens distention, resulting in decreased ventilation and hypoxia. Intraabdominal pressure is also transmitted into the thorax through the diaphragm resulting in increased intrathoracic pressures
gastrointestinal: impaired wound healing: gut wall oedema secondary to increased inflammatory mediators, decreased lymphatic flow, and capillary leakage. Potential translocation of bacteria through compromised GI tract.
hepatic: Decreased hepatic blood flow resulting in hypoxia and hepatic dysfunction. Possible acute hepatic failure
How do you measure intraabdominal pressure
u-cath. Two three-way stopcocks. Manometer 0 level at px symphysis pubis (level with tip of ucath) Empty bladder. Install 0.5-1 ml/kg of Nacl 0,9% in bladder. Fill manometer and the AP will be difference between the zero level (keep at the level of the tip of the ucath) and saline level in the manometer
give 5 risk factors for developing increased abdominal pressure and compartment syndrome
- severe shock, sepsis, pancreatitis
- high volume resuscitative fluids
- ARDS
- Mechanical ventilation
- Severe abdominal or pelvic injury +/- sx
- Ex lap
- GI perforations
- Bile peritonitis
- Abdominal masses
- pregnancy
give 5 non-surgical interventions to reduce intraabdominal pressure (prior to abdominal compartment syndrome)
- rectal decompression with enemas
- changing body position
- diuresis to remove excess fluid and oedema from tissues
- paracentesis to remove excess fluid from abdominal cavity
- haemodialysis
- neuromuscular blockade
- sedation
- analgesia
o epidural - prokinetics
- avoid overzealous fluid therapy
o consider hypertonic fluid to reduce the total fluid amount given - diuretics or dialysis if fluid overloaded
in tail pull injuries, what it most important prognostic factor for urination
neuro grade
How do you perform a closed reduction on a hip luxation on a craniodorsal luxation
- if no complicating factors and within 4-5 days of luxation
- Anesthetised animal
- Lateral recumbency with luxated leg dorsally/upwards
- robe in groin area to secure
- one hand on tarsus and other hand under limb, externally rotate the limb and pull caudally
- when femoral head lateral to acetabulum, rotate limb to set femoral head within acetabulum.
- Keep pressure on trochanter major and gently rotate the leg to get rid off clots and granulation tissue. 10-15 min
- Ehmer sling for 7-10 days (cats cage rest instead)
Describe how to place an ehmer sling
- thin layer of cast padding around metatarsal area and gauze around.
- maximally flex the stifle and bring gauze medially between body wall and limb and wrap thigh. pull firmly, bring gauze over front of knee to maintain flexion.
- wrap gauze over lateral surface of thigh (till knävecket) and bring it distally medial to the tarsus (twist at that point) and over the padded metatarsal area.
- Twist bandage and go medial to knee again. repeat the wrapping 3-4 times.
- Last turn ok to go over tibia and over back to secure. Always toes exposed. vet wrap runt
goal: knee in, hock out. never over the tibia unless for final lap that goes over the back
