Estimation of plasma fibrinogen levels based on hemoglobin, base excess and Injury Severity Score upon emergency room admission

Abstract

Introduction: Fibrinogen plays a key role in hemostasis and is the first coagulation factor to reach critical levels in massively bleeding trauma patients. Consequently, rapid estimation of plasma fibrinogen (FIB) is essential upon emergency room (ER) admission, but is not part of routine coagulation monitoring in many centers. We investigated the predictive ability of the laboratory parameters hemoglobin (Hb) and base excess (BE) upon admission, as well as the Injury Severity Score (ISS), to estimate FIB in major trauma patients.

Methods: In this retrospective study, major trauma patients (ISS ≥16) with documented FIB analysis upon ER admission were eligible for inclusion. FIB was correlated with Hb, BE and ISS, alone and in combination, using regression analysis.

Results: A total of 675 patients were enrolled (median ISS 27). FIB upon admission correlated strongly with Hb, BE and ISS. Multiple regression analysis showed that Hb and BE together predicted FIB (adjusted R2 = 0.46; loge(FIB) = 3.567 + 0.223.Hb - 0.007.Hb2 + 0.044.BE), and predictive strength increased when ISS was included (adjusted R2 = 0.51; loge(FIB) = 4.188 + 0.243.Hb - 0.008.Hb2 + 0.036.BE - 0.031.ISS + 0.0003.ISS2). Of all major trauma patients admitted with Hb <12 g/dL, 74% had low (<200 mg/dL) FIB and 54% had critical (<150 mg/dL) FIB. Of patients admitted with Hb <10 g/dL, 89% had low FIB and 73% had critical FIB. These values increased to 93% and 89%, respectively, among patients with an admission Hb <8 g/dL. Sixty-six percent of patients with only a weakly negative BE (<-2 mmol/L) showed low FIB. Of patients with BE <-6 mmol/L upon admission, 81% had low FIB and 63% had critical FIB. The corresponding values for BE <-10 mmol/L were 89% and 78%, respectively.

Conclusions: Upon ER admission, FIB of major trauma patients shows strong correlation with rapidly obtainable, routine laboratory parameters such as Hb and BE. These two parameters might provide an insightful and rapid tool to identify major trauma patients at risk of acquired hypofibrinogenemia. Early calculation of ISS could further increase the ability to predict FIB in these patients. We propose that FIB can be estimated during the initial phase of trauma care based on bedside tests.

Figures

Figure 1

Correlation between FIB and Hb, BE or ISS. Plasma fibrinogen concentration (FIB, mg/dL) versus (A) hemoglobin (Hb, g/dL), (B) base excess (BE, mmol/L) and (C) Injury Severity Score (ISS). The fitted regression line (solid) is shown along with a corresponding 95% confidence interval (dotted lines).

Figure 2

FIB stratified according to different categories of Hb, BE and ISS. Plasma fibrinogen concentration (FIB, mg/dL) stratified according to (A) hemoglobin (Hb, g/dL), (B) base excess (BE, mmol/L) and (C) Injury Severity Score (ISS).***P <0.001. Boxes indicate the range between the 25th and 75th percentile, whiskers represent the range between the 5th and 95th percentile, horizontal lines represents the median, and black circles represent outliers. Yellow areas represents FIB values between 199 and 150 mg/dL, red areas indicates FIB values below 150 mg/dL.

Figure 3

Combined admission variables resulting in a median plasma fibrinogen level (FIB, mg/dL). (A) Hemoglobin (Hb, g/dL) and base excess (BE, mmol/L), (B) Injury Severity Score (ISS) and Hb, and (C) ISS and BE. Green columns indicate adequate FIB (≥200 mg/dL), yellow columns indicate low FIB (<200 mg/dL), and red columns indicate critical FIB (<150 mg/dL).

Figure 4

Percentage of patients with adequate, low and critical FIB stratified according to Hb and BE. Observed percentage of patients with adequate plasma fibrinogen concentration (FIB) (≥200 mg/dL, green), low FIB (199 to 150 mg/dL, yellow) and critical FIB (<150 mg/dL, red) when combining the admission variables hemoglobin (Hb, g/dL) and base excess (BE, mmol/L).

Figure 5

Percentage of patients with adequate, low and critical FIB stratified according to ISS and BE. Observed percentage of patients with adequate plasma fibrinogen concentration (FIB) (≥200 mg/dL, green), low FIB (199 to 150 mg/dL, yellow) and critical FIB (<150 mg/dL, red) when combining the admission variables Injury Severity Score (ISS) and base excess (BE, mmol/L).

Figure 6

Percentage of patients with adequate, low and critical FIB stratified according to ISS and Hb. Observed percentage of patients with adequate plasma fibrinogen concentration (FIB) (≥200 mg/dL, green), low FIB (199 to 150 mg/dL, yellow) and critical FIB (<150 mg/dL, red) when combining the admission variables Injury Severity Score (ISS) and hemoglobin (Hb, g/dL).