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Departments of
*Anesthesia and Critical Care and
Surgery, Children’s Hospital and Regional Medical Center, University of Washington School of Medicine, Seattle, Washington
Address correspondence and reprint requests to A. Andrew Zimmerman, MD, Department of Anesthesia CH-05, Children’s Hospital and Regional Medical Center, 4800 Sand Point Way, Seattle, WA 98105. Address e-mail to azimme{at}chmc.org
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Case Report |
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The patient was brought to the operating room (OR) after being sedated with oral midazolam. After placement of routine monitors and the induction of anesthesia, appropriate IV and arterial access was secured in anticipation of major blood loss, and postoperative mechanical ventilation: a 20-gauge peripheral IV catheter in the right hand; a central venous catheter (5F, 15-cm, double-lumen catheter; Cook Critical Care, Bloomington, IN) via right femoral vein; and a right radial arterial catheter (22-gauge; Becton Dickinson, Sandy, UT). A precordial Doppler stethoscope was also placed to monitor for possible venous air embolism. Anesthesia was maintained with isoflurane (0.3%–0.8%) in an air/oxygen mixture, fentanyl (1–5 µg · kg-1 · h-1) and intermittent doses of pancuronium for neuromuscular blockade. During the procedure, arterial blood gases, complete blood counts, and coagulation studies were measured periodically. The patient had an estimated blood loss of 2000 mL and received the following fluid and blood component replacement: 3 L of lactated Ringer’s solution, 500 mL of 5% albumin, 500 mL of cell saver, 3 U of packed red blood cells, 2 U of fresh-frozen plasma, 2 U of platelets, and 50 mL of cryoprecipitate. Total anesthesia time was 14 h, and the patient was transported directly to the intensive care unit (ICU).
On arrival to the ICU, it was noticed that the patient’s right upper arm had a bluish discoloration that had not been identified in the OR. The right hand was mottled, but pulses were present by Doppler examination. Throughout the operative procedure and during the immediate postoperative period, the arterial line consistently had a good wave form and blood return. In addition, the IV catheter in the right hand had a good blood return with no sign of infiltration. At that time, we elected to remove the arterial and IV catheters from the patient’s right arm. Despite this, over the next several hours, she developed progressive ischemia and swelling in the right arm that seemed to progress proximally. The patient was taken back to the OR, where releasing fasciotomies were performed for a compartment syndrome. The artery was exposed at the wrist and was found to be thrombosed. Further discection revealed thrombus formation up to the junction of the brachial artery. A thrombectomy and an intraoperative angiogram with urokinase were performed. No evidence of venous thrombosis was identified. The patient was placed on a heparin infusion and was transferred back to the ICU. Over the next 10 days, the ischemic soft tissue regions along the fasciotomy margins further demarcated, which subsequently required debridement and split-thickness skin grafting.
There was no evidence of an iatrogenic prothrombotic state secondary to the patient’s transfusions because intraoperative and early postoperative coagulation variables were actually prolonged (PT 19 s, APTT 36 s, fibrinogen 132 g/dL) on arrival in the ICU. Postoperative evaluation for a possible prothrombotic disorder revealed that the patient had hereditary protein S deficiency. The patient’s protein S activity was reported as 34% (normal in our lab ranges from 65% to 150%). All other coagulation tests, including antithrombin III, protein C, and factor V Leiden, were normal. Family history revealed that the patient’s father had had one episode of a deep venous thrombosis, but he was not receiving anticoagulant therapy. Further studies revealed that he had the heterozygous form of protein S deficiency. The patient’s sister also tested positive for the disorder but has had no thrombotic episodes.
Fifteen weeks after the first procedure, additional extensive craniofacial surgery was planned. Similarly, this procedure was anticipated to require arterial and central venous catheters. Therefore, after consultation with the hematology service, several steps were taken to minimize the risk of recurrence of thrombosis. Preoperative coagulation tests were all normal, including a baseline thromboelastogram. A repeat protein S activity level was not performed.
A 4F, 8-cm, heparin-bonded, double-lumen catheter was placed in the left femoral vein. A custom heparin-bonded, 2.5F, 22-gauge, 8-cm, single-lumen catheter was placed in the right femoral artery, and pulse oximetry was monitored continuously in the right foot distal to the arterial line. Intermittent Doppler measurements were also made to assess patency of the femoral artery and its branches throughout the procedure. Direct visual examination of both catheter sites and both lower extremities was made throughout the case.
During the procedure, the patient had an estimated blood loss of 2000 mL, and she received 4 L of lactated Ringer’s solution, 250 mL of cell saver, 2 U of packed red blood cells, and 2 U of whole blood. At the end of the procedure, she was transferred directly to the ICU, where her arterial line was immediately removed. Hemostasis was achieved after 10 min of direct pressure at the site. Distal pulses were monitored at 30-min intervals after the catheter was removed, and at no time were the pulses diminished or lost. Twenty-four hours postoperatively, she was placed on low molecular weight heparin (LMWH; 1 mg/kg subcutaneously, twice a day), which was continued until her activity returned to normal just before discharge. Ventilator management was assisted by pulse oximetry, capnography, and venous blood gases, and the patient was extubated on the fourth postoperative day. The femoral venous line was removed on the sixth postoperative day when the port clotted, but a follow-up Doppler ultrasound that day showed no clots in the femoral venous system. The patient was discharged on the 12th postoperative day and had no signs of any thrombotic complications.
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Discussion |
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Protein S deficiency is inherited as an autosomal dominant trait. The homozygous protein S deficiency is extremely rare and is associated with life-threatening neonatal purpura fulminans (7). The heterozygous deficiency of protein S was first described as a cause of venous thrombosis in 1984 (8). The heterozygous protein S deficiency has been reported in many clinically affected families (8–11). The diagnosis is made by measuring quantitative levels of protein S antigen with an immunoradiometric assay. Protein S activity is also measured and reported as a percentage of normal. Most patients with protein S deficiency have normal coagulation tests (APTT, PT, fibrinogen, D-dimer, thrombin time) (12). In a review by Blanco et al. (12), 57% of pediatric patients had venous thrombosis, 20% had arterial thrombosis, and 14% had presented with both types. Our patient had the heterozygous form of the disease, which was also found in the patient’s father and sister.
Protein S deficiency is typically associated with venous thrombosis, especially during periods of immobility including pregnancy and surgery. Arterial thromboses, as in our case, have been associated with protein S deficiency, but are much less common. The current recommendation for children with protein S deficiency is prophylaxis with LMWH during times of immobility to prevent thrombotic complications (13). LMWH has several advantages over standard heparin, including lower bleeding complications and more predictable pharmacokinetics minimizing the frequency of monitoring (13). Because of the extensive anticipated intraoperative blood loss, we elected to defer LMWH therapy until 24 h after the procedure.
For the second surgical procedure, we also elected to use central venous and arterial catheters that were bonded with heparin. Bonding venous catheters with heparin decreases the incidence of catheter-associated thrombosis with the first 24 h of placement (14,15). Although the use of heparin bonding also reduces the incidence of arterial thrombosis (16), its use in arteries has been associated with significant bleeding at the site, especially upon removal (Brian Bates, personal communication, Cook Critical Care, Bloomington, IN, 1998). Despite this concern, we believed that the benefit of using a small, 2.5F, 22-gauge catheter bonded with heparin would outweigh the potential risk of bleeding at the site. During the procedure, we had direct access to the insertion site, and no bleeding was observed. Additionally, when the catheter was removed, hemostasis was achieved after only 10 min of direct pressure. Because the risk of arterial thrombosis with arterial catheters increases with the duration of placement, we elected to remove the arterial catheter immediately at the end of the surgical procedure (17,18). The central venous line was left in place at the end of the procedure only because of difficult venous access and the requirement for postoperative blood sampling.
Placement of the catheters was also controversial. Placing another arterial line in a peripheral artery may have been associated with an increased risk of thrombosis because of the small size of the vessels. We thought that placing the smallest available catheter in a relatively large artery would limit the risk of thrombosis. Because repeated access to the same vessel is associated with an increased risk of thrombosis, we placed the central venous catheter in the left femoral vein, which was not cannulated during the first procedure. Upper extremity lines were avoided because of the patient’s previous complication and because placing lines close to the surgical field would make it difficult to monitor them during the procedure.
In summary, we present a case of protein S deficiency presenting as an acute arterial thrombosis associated with peripheral arterial and venous catheters. We also have shown our approach to minimize the risk of thrombotic complications when this patient presented again for major surgery, using heparin-bonded catheters, early removal of the arterial catheter, and LMWH.
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This article has been cited by other articles:
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  P. Monagle, A. Chan, P. Massicotte, E. Chalmers, and A. D. Michelson Antithrombotic Therapy in Children*: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy Chest, September 1, 2004; 126(3_suppl): 645S - 687S. [Abstract] [Full Text] [PDF]
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P. Monagle, A. D. Michelson, E. Bovill, and M. Andrew Antithrombotic Therapy in Children Chest, January 1, 2001; 119(1_suppl): 344S - 370S. [Full Text] [PDF]
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