Undiagnosed Thrombocytopenia Results Right Below-Knee Amputation

Allegation 

Failure to timely diagnose and treat heparin-induced thrombocytopenia, resulting in limb ischemia and right BKA. 

Case Details 

The patient, a 56 YOF (5’2”, 202 lb) presented to the hospital for an off-pump CABG x3 using a non-aortic clamp technique with the left internal mammary artery to the LAD, reverse saphenous vein graft connected to the aorta using the PAS-Port device connected distally to the right coronary artery before its bifurcation; exclusion of the left atrial appendage using a 40 mm AtriClip; and bilateral endoscopic harvesting of the greater saphenous vein from the groin to below the knee on the left side and groin to lower leg on the right side. 

She had a history significant for an MI six weeks prior and a cardiac catheterization one week prior to presentation which demonstrated significant three-vessel coronary artery disease. Her co-morbidities included HTN, hyperlipidemia, CVA causing right-sided weakness, hepatitis, cluster headaches, depression, asthma, sleep apnea, glaucoma, and insulin-dependent diabetes. Surgical history included cholecystectomy, umbilical hernia, cyst removal from spine, and four negative breast biopsies. 

Post-procedure, the patient was noted to be neurologically intact and hemodynamically stable. She remained hospitalized for 6 days, during which endocrinology consulted regarding blood glucose management, physical and occupational therapy were ordered, and a CPAP was prescribed for use at bedtime. During her hospitalization she received 5,000 units heparin 1 mL 14 times. Platelet counts were taken at least once per day while admitted and ranged from 128-206. At admission, the platelet count was 143 and at discharge the count was 203. On the sixth day the patient was discharged from the hospital to be followed by home health. 

Three days after discharge, the patient returned to the cardiovascular surgeon with complaints of leg pain and possible infection. The surgeon noted no signs of infection and asked the patient to continue the Lasix until her scheduled appointment in two weeks. 

Four days later, the patient was seen by her PCP. She indicated she was not having much chest pain but was having right leg pain. She revealed she had increased swelling and pain prior to her appointment with her surgeon and was told her leg was not infected. She also told her PCP she had fevers post operatively but was not running a fever on that day. On exam, the left leg appeared to be healing well. There was right thigh tenderness to palpation with edema and induration on the dorsal thigh to buttock. The edema was extending to the foot. The erythema and tenderness tracked from the vein harvest site in the right calf to the vein harvest site in the right thigh. The PCP ordered Keflex to cover for possible phlebitis, wrote an order for a Doppler ultrasound to rule out DVT and instructed the patient to go to the emergency department for the assessment. 

The same day, the patient presented to the emergency department for the ultrasound with complaints of right leg pain and swelling since her surgery 12 days prior. She was evaluated by an emergency medicine resident who noted severe pain, moderate swelling, and moderate distress secondary to pain. Vital were BP 118/79, P 81, R 20, T 97.6, pulse ox was 97% on room air. Labs reveled WBC 17.3, RBC 2.91, Hgb 8.7, Hct 26.5, platelet 107, Neuro Auto 79.4, Lymph Auto 12.1. Her PTT was 32.7 and prothrombin time (PT) was 15.7. An ultrasound of the right lower extremity showed extensive occlusive deep venous thrombosis throughout the entire right lower extremity. The attending emergency medicine physician ordered heparin 4,500 units IV push and 14.5 mL/hr IV infusion with dosing by the pharmacy. The patient was admitted to the ICU. 

The next day, the patient received 4,500 units of heparin IV push and heparin 25,000 units continuous infusion. A CTA of the chest was completed. With findings of extensive bilateral pulmonary embolism, old granulomatous disease with discoid atelectasis versus scar involving both lungs. She was evaluated by the ICU resident. The plan was to continue heparin for treatment of the DVT and PE. An NP for the cardiothoracic service also evaluated the patient and agreed with the continued heparin. Labs drawn 10 hours after the administration of the heparin revealed a platelet count of 74 and PTT of 60.1. Five hours after the labs, the cardiothoracic surgeon evaluated the patient and agreed with the plan laid out by the NP and ICU resident which included continuation of the heparin. Finally, the patient was evaluated by the defendant internist. The internist noted the chief complaint was leg pain and the assessment included acute bilateral pulmonary embolism, right lower extremity DVT, coronary artery disease-status post-CABAG surgery, HTN, history of CVA, DM, morbid obesity, obstructive sleep apnea, leukocytosis, and anemia. He noted the patient was admitted to the ICU and started on IV heparin. An hour later, PTT was 62.9. An echocardiogram was planned with consultations from pulmonary and thoracic surgery. The defendant internist also noted he discussed the patient’s condition with the family at the bedside. 

The following day, the patient was evaluated by critical care, a platelet count of 58 was noted. The patient was also evaluated by a vascular surgery resident. He noted the consultation was requested to rule out compartment syndrome. Examination of the right extremity revealed no pain with passive movement of the leg. There was some toe discoloration noted in the greater and second toe. The patient could distinguish between blunt and sharp sensations and had positive biphasic Doppler in the posterior tibial and dorsalis pedis. The anterior compartment was tender to palpation. The leg was soft, and no firmness was noted. The resident did note a wound draining in the anterior compartment of the leg and notified his supervisors to determine next steps. The patient was told to notify nursing if the pain changed or worsened in any way and vascular checks were ordered Q1H. An order to discontinue heparin was entered. That evening, the defendant internist evaluated the patient. His plan was to continue the patient on IV heparin and request a consult from vascular surgery. 

The next day, the patient’s platelet count was 38 with a PTT of 126.6. She was evaluated by the vascular surgery resident who noted the platelet count and questioned heparin-induced thrombocytopenia (HIT). He noted medical management was done by the ICU team and was seeing the patient regarding follow up for possible compartment syndrome. An order to discontinue the heparin and start argatroban 50 mg was entered. Cardiology evaluated the patient and noted she had been diagnosed with thrombocytopenia and anemia. Another cardiologist evaluated the patient and noted she had blackening of the right first toe and right lower extremity cellulitis. 

The day after, the patient was evaluated by hematology. The hematologist noted her history and lab work, which indicated a platelet count of 58. He also noted her HIT antibody was 2.34. 

The defendant internist saw the patient the following day and noted she was anemic but made no mention of low platelets or HIT. Platelet and neutrophil immunology confirmed the diagnosis of HIT. The defendant internist, along with the ICU team, continued to follow the patient until the decision was made to transfer her to a different hospital for vascular intervention nine days later. 

Eight days after transfer for vascular intervention, the patient underwent a right below-the-knee amputation. 

Expert testimony and Resolution 

Experts were generally supportive of the care provided by the insured internist. However, HIT cases can be challenging to defend. When the case involves multiple departments, numerous providers, and their differing responsibilities to the patient, the case can become even more challenging to defend. Consequently, the defense elected to settle this case for a reasonable, confidential amount. 

Risk Reduction Strategies 

Communication is key, not just communication with the patient, but communication with the other healthcare providers. This is particularly important when treating patients in the ICU, whether a closed or semi-closed ICU. Physicians need to be clear on their responsibility to the patient and clearly communicate with the other healthcare providers to be sure the patient is receiving optimal care. In cases involving HIT, it can be extremely challenging if the providers are not communicating the results of lab work and responding appropriately. In this example, the physicians were not clearly communicating with each other and in some instances, were changing medication orders without speaking to the other providers, which added to the difficulty in defending the case. 

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