Compartment Syndrome

Keep the pressure up - The compartment is perfused by the gradient between the patient's blood pressure and the compartment pressure. Hypotension shrinks that gradient and extends the ischemia, so a deep anesthetic or a permissive-hypotension strategy is actively harmful in a limb at risk. Treat hypotension early rather than watching it drift.

Delta pressure is the number that decides - Delta p is diastolic blood pressure minus compartment pressure. A delta p under 30 mmHg, or an absolute compartment pressure over 30 mmHg, indicates fasciotomy, and some centers operate at a delta of 20 mmHg. One normal reading does not exclude the diagnosis — the pressure has to be trended serially or measured continuously.

Pain out of proportion, and pain on passive stretch - Those are the early findings and they are close to pathognomonic. The classic five Ps — pain, pulselessness, paresthesia, paralysis, pallor — are all late except paresthesia. A palpable pulse means nothing here: systolic pressure usually exceeds compartment pressure, so pulses persist in a limb that is dying.

The regional anesthesia argument, honestly - The findings everyone is relying on are pain-based, and they are unreliable or absent in the patient who is unconscious, sedated, has nerve damage, is a child, or has had a regional block for pain relief. That is the real objection to a dense block in an at-risk limb — not that blocks cause compartment syndrome, but that they remove the monitor. If you do block that limb, say so explicitly to the surgical team and get compartment pressure monitoring arranged, because pressure becomes the endpoint in place of pain.

Escalating analgesia is the tell - A rising analgesic requirement, and in children anxiety alongside it, is a reliable indicator. A block or epidural that keeps needing topping up in a fractured limb is a reason to measure a pressure, not a reason to give more drug.

Lithotomy causes it - Well-leg compartment syndrome occurs in roughly 1 in 3500 patients positioned in lithotomy, in the anterior and lateral compartments, because hip and knee flexion impairs venous drainage and raises lower limb venous pressure. Keep hip and knee flexion under 90 degrees, hip abduction under 45 degrees, and the hip in neutral rotation. If the case will run past four hours, lower the legs for a few minutes every two hours.

The rest of the routine-care causes - Tight casts, splints, and circumferential dressings; malfunctioning sequential compression devices; poorly fitted compression stockings; intramuscular or intracompartmental injections; intraosseous lines; extravasated hypertonic fluid or contrast; bleeding into a compartment from an attempted arterial or venous cannulation; and pressurized pulsatile irrigation. Uni-valving or bi-valving a cast drops the pressure by about half.

An open fracture does not protect the compartment - A skin laceration does not decompress the muscle compartments underneath it. Open tibial fractures still develop compartment syndrome, and the patients who develop it without any fracture at all are the ones who get diagnosed late and do worst.

Time is the whole prognosis - Fasciotomy within six hours gives near-complete recovery of limb function. By twelve hours only about two-thirds recover normally, and beyond that roughly 8% do. Fasciotomy is not recommended after 36 hours. In one series of combat casualties, delayed fasciotomy carried twice the amputation rate and three times the mortality.

Plan the emergency fasciotomy as a general anesthetic - Fasciotomy is performed under general anesthesia, usually urgently, often in a patient with other injuries. Expect a return to the operating room at 48 to 72 hours for a second look and debridement, and about half of these wounds eventually need split-thickness skin grafting.

Reperfusion is the renal event - Rhabdomyolysis complicates up to 23% of acute compartment syndrome cases and presents as muscle stiffness, muscle and back pain, and dark or scant urine. Once the compartment is released, reperfusion can drive multiorgan failure. Follow CPK, BUN, creatinine, serum electrolytes, calcium, and urine myoglobin, keep the patient well hydrated, watch the arterial blood gases, and correct the electrolyte disturbances. Acute renal failure at this point is managed with intravenous fluids and dialysis.

Compartment syndrome is a rise in pressure inside a closed osteofascial compartment to the point that the tissue inside can no longer be perfused. Fascia is thin and inelastic, so a compartment cannot expand to accommodate bleeding or swelling.

As pressure climbs, venous outflow collapses first and venous capillary pressure rises. Once compartment pressure approaches arterial inflow pressure, arterial inflow falls as well, and the muscle and nerve inside go ischemic. Ischemic cells release histamine-like mediators that increase capillary permeability, and lysing cells draw in water osmotically, so the process feeds itself. Normal compartment pressure is under 10 mmHg; 30 mmHg or more is diagnostic. Because perfusion depends on the gradient between systemic pressure and compartment pressure, systemic hypotension directly worsens the ischemia. Fasciotomy is the only treatment, and outcome is decided almost entirely by how quickly it happens.