Cardiac troponin and skeletal muscle oxygenation in severe post-partum haemorrhage

Abstract

Introduction: Cardiac troponin has been shown to be elevated in one-half of the parturients admitted for post-partum haemorrhage. The purpose of the study was to assess whether increased cardiac troponin was associated with a simultaneous alteration in haemoglobin tissue oxygen saturation in peripheral muscles in post-partum haemorrhage.

Methods: Tissue haemoglobin oxygen saturation of thenar eminence muscle (StO2) was measured via near-infrared spectroscopy technology. Two sets of StO2 parameters (both isolated baseline and during forearm ischaemia-reperfusion tests) were collected at two time points: upon intensive care unit admission and prior to intensive care unit discharge. Comparisons were performed using Wilcoxon paired tests, and univariate associations were assessed using logistic regression model and Wald tests.

Results: The 42 studied parturients, admitted for post-partum haemorrhage, had clinical and biological signs of severe blood loss. Initial cardiac troponin I was increased in 24/42 parturients (0.43 +/- 0.60 microrg/l). All measured parameters of muscular haemoglobin oxygen saturation, including Srecovery, were also altered at admission and improved together with improved haemodynamics, when bleeding was controlled. Multivariate analysis showed that muscular Srecovery <3%/second at admission was strongly associated with increased cardiac troponin.

Conclusions: Our study confirmed the high incidence of increased cardiac troponin, and demonstrated the simultaneous impairment in the reserve of oxygen delivery to peripheral muscles in parturients admitted for severe post-partum haemorrhage.

Figure 1

Thenar muscle tissue haemoglobin oxygen saturation in a patient hospitalized for severe post-partum haemorrhage. Representative example of thenar muscle tissue haemoglobin oxygen saturation (StO₂) at admission and at intensive care unit discharge in the same patient. Set of measurements: StO₂ at baseline, during cuff inflation (S_occlusion) and after cuff release (reperfusion phase, S_recovery). cTnI, cardiac troponin I (normal range <0.04 μg/l).

Figure 2

Tissue haemoglobin oxygen saturation ascent at admission. Upper panel: bimodal distribution of the baseline ascent slope (S_recovery). Lower panel: most parturients (16/18) with negative cardiac troponin I (cTnI) showed S_recovery >3%/second, only 13% had negative cTnI. *P < 0.002.

Figure 3

Association of tissue haemoglobin oxygen saturation ascent with plasma troponin I. Receiver operating characteristic curve of tissue haemoglobin oxygen saturation ascent (S_recovery) to association with plasma troponin I. AUC, area under the curve; NPV, negative predictive value; PPV, positive predictive value.