Corresponding Author
Ryo Ichibayashi, MD, PhD
ORCID iD https://orcid.org/0000-0002-1273-4875
Department of Critical Care Center
Toho University Medical Center Omori Hospital
6-11-1 Omori-Nishi
Ota-ku, Tokyo 143-8541, Japan
Phone: +81-3-3762-4151
Fax: +81-3-3-3765-6518
e-mail: ryou.ichibayashi@med.toho-u.ac.jp
KEY CLINICAL MESSAGE
Measurement of L-FABP levels can aid in indicators of circulation and management of VA-ECMO. L-FABP levels can be measured in approximately 10 minutes, the advantage over lactate is the non-invasive results from the urine test.
ABSTRACT
Herein, we discuss a case in which L-FABP measurements were used to manage a 46-year-old male patient receiving VA-ECMO support. His mean blood pressure was ≥ 75 mmHg for the first 24 h after the initiation of VA-ECMO, and he experienced a rapid decrease in L-FABP.
KEYWORDS
Liver-type fatty acid-binding protein, extracorporeal membrane oxygenation, lactate, circulation index
1 INTRODUCTION
Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is applied in circulatory failure cases such as cardiogenic shock, cardiac arrest, and refractory ventricular fibrillation. VA-ECMO management includes echocardiographic assessments of cardiac function and evaluations of peripheral circulation based on venous oxygen saturation, lactate levels, regional cerebral oxygen saturation, and central venous pressure. ECMO flow rates exceeding cardiac output result in low pulse pressure, leading to low mean blood pressure. Thus, the mean blood pressure is also used to manage organ perfusion and peripheral circulation during ECMO support.
Urinary liver-type fatty acid-binding protein (L-FABP)—a biomarker of renal ischemia—has also been considered to reflect acute systemic ischemic injury and to be effective in the assessment of sepsis treatment [1,2]. However, no reports have discussed L-FABP use during VA-ECMO management in severe ischemic injury after cardiac arrest cases.
Herein, we discuss a case in which L-FABP measurements were used during VA-ECMO management.
2 CASE HISTORY
The patient was a 46-year-old man who had collapsed at home, following which a witnessing family member called for an ambulance and performed chest compressions until the emergency medical team’s arrival. Monitor waveforms at the time of their arrival indicated ventricular fibrillation. The team performed cardiac massage, secured the airway with a laryngeal tube, and defibrillated the patient three times, following which he was transported to our hospital. Extracorporeal cardiopulmonary resuscitation was performed on arrival, given the persistence of ventricular fibrillation. The interval from cardiac arrest to resuscitation with VA-ECMO cannulation was 45 minutes.
Based on the increase in creatine kinase-muscle/brain (CK-MB) levels and electrocardiographic changes, acute myocardial infarction was suggested, and emergency coronary angiography was performed (Table 1). Coronary angiography revealed significant stenosis in branch #6 of the left anterior descending artery, which led to a diagnosis of acute myocardial infarction. Percutaneous coronary intervention (PCI) was performed, following which an intra-aortic balloon pump (IABP) was inserted. The patient was admitted to the intensive care unit (ICU), where targeted temperature management (TTM) was performed at 34°C for 24 h. Thereafter, the patient’s body temperature was gradually restored to 36°C over 2 days.
Figure 1 shows changes in L-FABP levels, lactate levels, mean blood pressure, daily fluid balance, flow rate, and other parameters during ICU admission. Values measured from urine collected before ECMO cannulation on arrival were regarded as baseline values, and urine L-FABP and serum lactate levels were measured every 6 h. L-FABP levels were also measured every 24 h after weaning. On arrival, the patient’s L-FABP level was 74,100 μg/gCr, which decreased to 816 μg/gCr at 24 h after admission, at which time the lactate level, which had also been high, decreased to 2.4 mmol/L. Twenty-four hours after arrival, the ECMO flow rate was 2.6–3.6 L/min; mean blood pressure, 76–97 mmHg; and pulse pressure, 42–60 mmHg. On and after hospital day 2, the patient’s lactate levels remained at 0.9–1.0 mmol/L. However, his mean blood pressure increased, while L-FABP levels decreased.
On hospital day 5, the patient was weaned off VA-ECMO without deterioration of L-FABP levels, lactate levels, or mean blood pressure. On hospital day 6, he was weaned off IABP without changes in mean blood pressure or lactate levels. Thereafter, although the mean blood pressure remained unchanged, L-FABP levels temporarily increased, following which they decreased again. During the same period, the daily fluid balance was negative on consecutive days. On hospital day 8, he could follow instructions and was weaned off mechanical ventilation and extubated on hospital day 10. On hospital day 13, he was discharged from the ICU and transferred to the general ward. On hospital day 24, no neurological sequelae were noted, and he was discharged from our hospital with independent gait.
3 DISCUSSIONS
Lactate levels increase owing to tissue hypoxia resulting from circulatory failure or insufficient oxygen supply. Therefore, improving circulation or oxygenation should decrease lactate levels. However, some patients with normal hemodynamics and oxygenation exhibit elevated lactate levels due to the influence of underlying diseases such as sepsis and malignant tumors [3]. Such elevation may be attributed to increased lactate production, decreased lactate consumption, or both in various organs such as the muscles, skin, and brain. Contrastingly, FABPs are specifically distributed in various tissues [4]. For example, urinary L-FABP, which is released from proximal tubule cells, has been highlighted as a strong biomarker of acute ischemic injury [1]. Given that L-FABP is unlikely to be affected by other factors, it may represent a more sensitive hemodynamic indicator than lactate.
During ECMO, the mean blood pressure is often maintained at ≥ 65 mmHg. However, there are no clear criteria for the index value, and the target value varies across institutions. Although one report suggested a higher survival rate among patients managed with a target mean blood pressure of 70–80 mmHg [5], the optimal mean blood pressure is considered to differ for each patient. L-FABP levels should decrease if patients are managed with optimal mean blood pressure, suggesting they can aid in blood pressure management.
Our patient’s mean blood pressure was ≥ 75 mmHg for the first 24 h after VA-ECMO initiation, and he experienced rapid decreases in both L-FABP and lactate levels. In this case, the target mean blood pressure was 70 mmHg, and weaning from VA-ECMO was eventually successful. Since both L-FABP and lactate levels were low during weaning, L-FABP also appeared to be an appropriate hemodynamic index for VA-ECMO management.
In patients managed with a mean blood pressure of ≥ 70 mmHg who exhibit normal lactate levels, temporary increases in L-FABP may occur following extubation, as observed in our patient. During this period, the daily fluid balance is adjusted between –500 and –5,000 mL to achieve successful extubation or improve systemic edema. Therefore, the volume of fluid replacement is maintained at the minimum level to ensure a relatively higher urinary output. Thus, L-FABP levels may reflect a slight shortage of intravascular volume that is not reflected by lactate levels.
Our findings suggest that L-FABP can be used as a hemodynamic indicator for managing patients receiving VA-ECMO support and it can be used equivalently to conventional hemodynamic indicators such as lactate and mean blood pressure. Thus, Measurement of L-FABP levels appears to be useful for determining whether to increase or decrease the flow rate of VA-ECMO, and determining whether weaning from VA-ECMO is appropriate. Unfortunately, LFABP failed to prove to be more sensitive than traditional hemodynamic indicators such as lactate and mean blood pressure. However, this study is suggested that L-FABP may be more sensitive than lactate in controlling intravascular water balance. Therefore, it is necessary to accumulate and investigate cases in the future. L FABP measurement has a Limitation. Since L-FABP levels are measured from urine samples, they cannot be used for patients undergoing dialysis or those with anuria in the early stage of shock. As strong point of test, L-FABP levels can be measured in approximately 10 minutes, and the results can be obtained more non-invasively than blood tests.
CONFLICT OF INTEREST
None declared.
AUTHOR CONTRIBUTIONS
RI: wrote and drafted the manuscript
SY: measured L-FABP and lactate levels
YN: drafted the manuscript
YM: measured L-FABP and lactate levels
HS: drafted the manuscript
MW: drafted the manuscript
TY: drafted the manuscript
MH: drafted the manuscript
All authors read and approved the final manuscript
ETHICAL APPROVAL
The present study was approved by the Toho University Medical Center Omori Hospital Ethics Committee. Informed consent was obtained from participants or their family members prior to enrollment and after receiving written explanations about the aims and procedures used in the study (Approval No. M19141).
CONSENT
Written informed consent was obtained from the patient for publication of this case report.
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.