To minimize thromboembolic complications and maintain patency of the circuit, proper anticoagulation is essential during ECMO. Bleeding complications are one of the most common problems in elderly patients who undergo ECMO, and they are also an important cause of accidental death. In this study, three patients had retroperitoneal hemorrhage beyond 7 days after ECMO initiation. There were no related trauma or iatrogenic procedures. Current risk factors for idiopathic retroperitoneal hemorrhage include anticoagulation, antiplatelet therapy, and chronic renal failure8.
Retroperitoneal bleeding itself is difficult to diagnose and can present with nonspecific symptoms. The literature indicates that 10.1% of retroperitoneal hemorrhages are misdiagnosed or never diagnosed4. Ranney D, et al pointed out that retroperitoneal hemorrhages should be considered when ECMO fluctuates or ECMO circuit flow rates are low despite volume infusion9. During ECMO, bleeding situations, such as bleeding at the puncture site and gastrointestinal bleeding, can easily cover a retroperitoneal hemorrhage. At present, CT is the first recommendation for diagnosing retroperitoneal hemorrhage, and ultrasound is only accepted as an evaluation criterion10. Three patients in this study were diagnosed with retroperitoneal hemorrhage by CT and routinely monitored by ultrasound.
The three patients with COVID-19 in this study were elderly patients who underwent ECMO for severe ARDS. Low platelet levels (< 50 103/µL) during ECMO have become one of the reasons for the formation of retroperitoneal hemorrhage. Among them, the patient in Case 3 had experienced a replacement of an ECMO oxygenator before the retroperitoneal hemorrhage. This operation gave rise to a transient consumption of coagulation substances. During the first 4 hours after oxygenator replacement: APTT 78.7 s; prothrombin time intertional normalized ratio (PT-INR): 1.2; and platelets 94*109/L. This may cause bleeding, which should cause alarm.
In addition to antithrombotic therapy, other causes of retroperitoneal hemorrhage include trauma and benign and malignant renal tumors11. Three cases of retroperitoneal hemorrhage in this report showed multiple diffuse bleeding, and physical shock should be considered first. The course of COVID-19 was long, and protective clothing increased the difficulty of caretaking for the nursing staff. Inadequate care of the body position, particularly the waist and back, and the frequent prone position for the treatment of patients and imaging examinations can cause long-term compression of the waist and back and affect blood circulation.
Another possible mechanism is bleeding from rehabilitation injuries because two of the patients had bleeding after rehabilitation. Therefore, specific programs should be developed for elderly patients with ECMO to reduce the incidence of retroperitoneal hemorrhage. At present, there are similar reports of retroperitoneal hemorrhage during ECMO, but the etiology and early diagnosis are less discussed12. Three cases were reported in our center at one time, and the pathogenesis and possible causes were analyzed. These three patients received care and active support in the intensive care unit (ICU), including blood transfusions, coagulopathy reversal, and radiation interventions. The patients in case 1 and case 2 underwent TAE hemostasis within 2 hours; the patient in case 3 was treated with corrected blood coagulation to reduce postural injury and recover from injury. If patients have a significant decrease in hemoglobin and exhibit shock, early TAE treatment is recommended.
Retroperitoneal hemorrhages in patients with ECMO often have severe consequences. Some suggestions are as follows: elderly patients need a combination of awake ECMO and rehabilitation; patients should use anticoagulation reduction standards; changes in blood coagulation function and hemoglobin should be closely monitored; routine ultrasound examination should be performed to determine the occurrence of retroperitoneal hemorrhages; if ECMO patients undergo a transfer, a patient transfer board and other aided measures are recommended; and if patients complain of lower back pain, with decreased Hb, or decreased ECMO flow, retroperitoneal bleeding should be considered.