Polyarteritis Nodosa (PAN)

Hypertension is renin-driven - Patients with renal involvement most often present with hypertension, and it is mediated through activation of the renin-angiotensin system. First-line treatment is an ACE inhibitor, with a calcium channel blocker as the alternative when GFR falls. Find out whether the ACE inhibitor was taken the morning of surgery and expect a labile pressure through the case.

Renal function - Check serum creatinine and urinalysis. Renal failure is one of the major causes of death in PAN, and long-standing hypertension compounds it. Dose renally cleared drugs accordingly and hold perfusion pressure rather than running the patient dry.

Mesenteric arteritis - Mesenteric involvement predominantly affects the small intestine and produces postprandial abdominal pain, the classic "intestinal angina," along with nausea, vomiting, melena, and diarrhea. Severe disease progresses to ischemia and perforation, and bowel perforation is one of the operations these patients actually present for. Approach the acute abdomen in PAN as ischemic bowel: volume deficits, acidosis, and sepsis physiology.

Aneurysms rupture - Mesenteric or renal arteriography shows aneurysms and constrictions in the larger vessels with occlusion of smaller arteries, and renal artery aneurysms can rupture. Surgery is often needed for aneurysms, bowel perforation, and cholecystitis. Sudden unexplained hypotension with abdominal pain is a rupture until proven otherwise.

Cardiac - Vasculitis of the coronary arteries plus long-standing hypertension leads to heart failure and myocardial infarction, and MI is a listed cause of death. Baseline ECG and echocardiogram when there is dyspnea, edema, or known cardiac involvement.

Document mononeuritis multiplex first - It is the most common neurologic deficit in PAN, in nearly 70% of patients, most often involving the radial, ulnar, and peroneal nerves with both sensory and motor loss. Those are the same nerves at risk from positioning, so an undocumented baseline becomes your problem in the PACU.

Hepatitis B and C - Secondary PAN is associated with hepatitis B, usually within the first six months of infection, and with hepatitis C. Check the hepatitis serologies and liver panel already in the chart: hepatic function affects drug metabolism and coagulation, and antivirals are part of these patients' treatment.

Steroids and immunosuppression - Mild disease is treated with prednisone 1 mg/kg/day up to 60 to 80 mg, tapered over six to eight months; moderate to severe disease adds cyclophosphamide, azathioprine, or methotrexate. Give a perioperative stress-dose steroid and treat these patients as immunocompromised — deaths in PAN are frequently from complications of the immunosuppressive therapy itself.

Skin - Tender erythematous nodules resembling erythema nodosum, palpable purpura, livedo reticularis, ulcerations, and digital ischemia, mostly on the lower extremities. Pad pressure points, be careful with adhesives over involved skin, and document existing lesions.

The lungs are usually spared - PAN chiefly affects the skin and other organs but typically leaves the lungs alone, which is the opposite of the ANCA-associated vasculitides. A normal chest exam and imaging is the expectation here; if the lungs are involved, reconsider the diagnosis.

Neurologic prognosis - CNS involvement portends a poor prognosis and cerebral infarction is a listed cause of death. Keep blood pressure within the patient's own usual range rather than chasing a textbook number, particularly in a chronically hypertensive patient with a rightward-shifted autoregulation curve.

Muscle - Myalgias and generalized weakness are common when muscle is involved. Check a creatine kinase when myopathy is suspected and titrate neuromuscular blockade to a peripheral nerve stimulator.

Polyarteritis nodosa (PAN) is a systemic necrotizing vasculitis of medium-sized arteries that, unlike the ANCA-associated vasculitides, is typically ANCA-negative and characteristically spares the lungs. Inflamed vessels thicken by intimal proliferation, which narrows the lumen, reduces flow, and predisposes to thrombosis; at the same time the inflamed wall weakens and forms aneurysms. The result is ischemia and infarction across the kidney, gut, nerve, skin, heart, and muscle.

The kidney is the most commonly affected organ. Renal artery inflammation produces aneurysms that can rupture, while luminal narrowing causes glomerular ischemia that activates the renin-angiotensin system and drives hypertension. Most PAN is primary and idiopathic; secondary disease is classically associated with hepatitis B, usually within the first six months of infection, and also with hepatitis C and hairy cell leukemia.