Appropriate implementation of regional anesthetic techniques requires careful assessment of perceived risks and benefits with special emphasis on patient factors, including current medications, comorbid medical conditions, and cognitive–behavioral characteristics as well as procedural factors including length, complexity, and anatomic location of the operative site. Psoas compartment (i.e., lumbar plexus) blockade is a commonly performed regional technique for orthopedic procedures involving the hip, anterior thigh, and knee. Although it is technically considered a peripheral nerve block, there remains concern for bleeding given the depth and proximity of the lumbar plexus to the neuraxis. Indeed, several cases of clinically significant bleeding have been described in the literature.1–4
When present, preoperative coagulation tests and patient medications should be fully reviewed before needle placement in an attempt to avoid bleeding complications in patients undergoing psoas compartment blockade. Although thrombocytopenia is considered a risk factor for periprocedural bleeding complications, the platelet count is not always a reliable marker of platelet function, and it is possible that significant hemorrhagic complications may occur at normal or supratherapeutic platelet values. We present the case of a patient with myeloproliferative thrombocytosis who underwent total hip arthroplasty with preoperative psoas catheter placement. His perioperative course was complicated by the rapid development of a large and hemodynamically significant retroperitoneal hematoma within 1 hour of needle placement. Written informed consent for publication of this report was obtained from the patient, and the authors were directly involved in the patient’s perioperative care.
An 87-year-old, 80-kg (body mass index 19 kg/m2) man with a 2-year history of a myeloproliferative neoplasm consistent with essential thrombocytosis was scheduled for an elective left total hip arthroplasty secondary to severe degenerative changes. He had baseline platelet counts between 600 and 700 × 109/L and had been receiving high-dose hydroxyurea therapy for approximately 1 year in an effort to decrease his supraphysiologic platelet count and prevent thrombotic complications. Of note, he had experienced no previous thrombotic or bleeding complications and had a hemoglobin value of 11.5 g/dL the day before the procedure. One week before the scheduled surgery, 325 mg aspirin therapy twice daily was initiated for deep venous thrombosis prophylaxis, as is the routine for his orthopedic surgeon.
After standard American Society of Anesthesiologists monitors were placed, the patient was sedated with 2 mg IV midazolam and 100 μg IV fentanyl and a left-sided psoas compartment catheter was placed in the right lateral decubitus position with an 18-gauge, 4-inch insulated Tuohy needle (Contiplex®; B Braun, Bethlehem, PA) using nerve stimulation.5 Continuous psoas compartment block was chosen over epidural analgesia for this patient given the desire for unilateral postoperative sensory blockade with minimization of common epidural-related side effects including hypotension, pruritus, and urinary retention. Several passes were required before obtaining an adequate quadriceps twitch at 1.5 mA, which diminished appropriately but was still present at a current of 0.5 mA. Although the catheter threaded easily, there was blood on initial aspiration. The catheter was removed and then subsequently replaced with negative aspiration. He received an uneventful initial loading dose of 30 mL of 0.5% bupivacaine with 1:200,000 epinephrine.
Approximately 20 minutes after regional block placement, the patient underwent IV induction of general anesthesia with propofol, succinylcholine, and fentanyl followed by direct laryngoscopy and uneventful endotracheal intubation. However, over the ensuing 15 minutes, the patient became progressively hypotensive with mean arterial blood pressure readings of 40 mm Hg. There were no changes in respiratory status to suggest an anaphylactic reaction and no signs of acute surgical blood loss or a cardiopulmonary event. A radial arterial line was placed, and a phenylephrine infusion was initiated in addition to aggressive fluid resuscitation with both crystalloid and 5% albumin solutions. These efforts resulted in successful restoration of arterial blood pressure. He was tracheally extubated uneventfully at the completion of the procedure, and vasopressor support was discontinued before operating room exit. Estimated blood loss for the 2-hour case was 250 mL.
On arrival in the postanesthesia care unit, the patient again became profoundly hypotensive with mean arterial blood pressure readings between 30 and 40 mm Hg. Laboratory evaluation revealed a hemoglobin level of 5.2 g/dL from a baseline of 11.7 g/dL. He was transfused 3 units of packed red blood cells. His physical examination was unremarkable, including no flank hematoma and no signs of excessive bleeding from the surgical site or drains. Despite the lack of physical examination findings, an urgent computed tomography scan of the abdomen and pelvis was obtained <7 hours after needle placement, which revealed a large retroperitoneal hematoma (Fig. 1). He was transferred to the intensive care unit (ICU) for further evaluation and management, at which time the psoas catheter was removed given normal coagulation parameters including a platelet count between 300 and 400 × 109/L. His hemoglobin was monitored every 4 hours for the first 24 hours, remaining >7.0 g/dL at all times. No surgical intervention was required. The patient’s pain was well controlled with fentanyl patient-controlled analgesia, oral oxycodone, and oral acetaminophen. His average pain score was 4 of 10 in severity after removal of the psoas catheter. He was transferred out of the ICU on postoperative day 2, and 325 mg aspirin twice daily was reinitiated. He received an additional 2 units of red blood cells on postoperative day 4 for a hemoglobin value of 7.4 g/dL. He was discharged home on postoperative day 6. A repeat computed tomography scan 2 weeks later showed significant resolution of the retroperitoneal hematoma. There were no neurologic sequelae.
The development of a retroperitoneal hematoma after lumbar plexus block is a rare complication, which has been described several days to weeks after needle placement and in the setting of high-dose low-molecular-weight heparin (LMWH) and unfractionated heparin therapy.1–4 In most of these cases, multiple needle passes were required for block placement. In addition, the timing between needle placement and LMWH administration would be considered noncompliant with the most recent American Society of Regional Anesthesia and Pain Medicine guidelines, which recommend at least 6 to 8 hours between block placement and medication administration for single daily dosing and 24 hours for twice-daily dosing.6 Indwelling catheters should be removed before initiation of twice-daily dosing of LMWH but may be maintained with once-daily dosing regimens. With once-daily dosing, catheters should be removed a minimum of 10 to 12 hours after the last dose of LMWH.
The safety of regional anesthesia in the setting of aspirin therapy in doses >325 mg daily remains understudied, although American Society of Regional Anesthesia and Pain Medicine guidelines do not recommend avoiding either single-shot or catheter techniques.6 In addition, there are no specific concerns regarding the timing of aspirin administration in relation to needle placement. Aspirin, a nonreversible inhibitor of cyclooxygenase, prevents the formation of thromboxane A2, which is a known prothrombotic agent involved in platelet activation and aggregation. Theoretically, low-dose aspirin (<325 mg daily) may pose greater bleeding risk than higher doses because increasing doses may paradoxically result in prothrombogenic effects secondary to prostacyclin inhibition.6
Little is known regarding the safety of regional anesthesia in patients with myeloproliferative neoplasms including essential thrombocytosis, although these patients are known to be at high risk for both thrombotic and bleeding complications. One potential mechanism for the paradoxical increase in hemorrhage risk in essential thrombocytosis is related to the development of acquired von Willebrand deficiency, which occurs because of the cleavage of large von Willebrand factor (vWF) multimers by the ADAMTS13 cleaving protease in a manner that is dependent on platelet count such that greater loss of functional vWF occurs with higher platelet counts.7 However, this relative deficiency may not be readily apparent with basic quantification of vWF or factor VIII antigen levels but rather requires laboratory assessment of vWF function such as ristocetin cofactor activity. Although bleeding complications can occur at any platelet count, it is most commonly seen in the setting of thrombocytosis with platelet counts exceeding 1000 × 109/L.8–11 Advanced age and a history of bleeding complications are also known risk factors for hemorrhage in these patients.12
In addition to acquired von Willebrand deficiency, platelet dysfunction may occur because of increased platelet activation, decreased adrenergic receptor expression, impaired adrenergic responsiveness to epinephrine, acquired platelet storage pool deficiency, and decreased platelet membrane glycoprotein expression.7 Interestingly, concomitant use of aspirin in excess of 325 mg daily has been associated with hemorrhagic complications in patients with myeloproliferative thrombocytosis, because this may unmask an underlying bleeding diathesis.13 In our patient, 650 mg aspirin therapy daily, coupled with multiple needle passes and an underlying increased bleeding risk associated with his disease, may have significantly contributed to his hemorrhagic complication.
In our case, a large retroperitoneal hematoma associated with hemorrhagic shock developed within 1 hour of needle placement in a patient with myeloproliferative thrombocytosis receiving high-dose aspirin therapy. The bleeding complication was recognized early and managed appropriately with no neurologic deficits. Although many would advocate waiting for the correction of coagulopathy before regional catheter removal, there is notably little evidence to guide the removal of regional catheters in the setting of ongoing bleeding or coagulopathy. In this case, the psoas catheter was removed at the discretion of the ICU team after reassurance of a normal laboratory coagulation profile and concern for the future development of worsening coagulopathy. We advocate that regional anesthetic techniques should be used cautiously in patients with myeloproliferative disorders, especially in the setting of concomitant aspirin therapy. Suspicion of bleeding should be heightened in the setting of hypotension and multiple needle passes. In these patients, the presence of supraphysiologic platelet counts does not provide assurance of normal hemostasis.
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