In this example, a 52-years-old female patient presenting symptoms consistent with the Class II Functional Classification of the NYHA received mitral valve replacement using the cardiopulmonary bypass technique. After surgery, the patient experienced a profuse bleeding at the Intensive Care Unit, so emergency re-operation was carried out [1].

[1] Beltran, N. E., et al. "The predictive value of gastric reactance for postoperative morbidity and mortality in cardiac surgery patients." Physiological measurement 31.11 (2010): 1423.

[2] Andersen, Lars W., et al. "Etiology and therapeutic approach to elevated lactate levels." Mayo Clinic Proceedings. Vol. 88. No. 10. Elsevier, 2013.

Fig. 1 Changes of Reactance Biomarker (XL) during the monitoring period vs lactate and mean arterial pressure (MAP).  Female patient, 52 years old, operated for mitral valve replacement. Parsonnet score of 39, NYHA of 2. Complications: profuse bleeding in ICU (3100 mL). Emergency re-operation, hypovolemic shock and death during monitoring. Events: (a) patient bleeding,(b) transfusion, (c) bleeding 600 mL in 1 h, (d) plasma transfusion, (e) bolus of norepinephrine and start adrenaline, hemorrhage and hypovolemic shock, and (f) death.

 At the time the patient was admitted, the Reactance Biomarker (XL) increased abnormally while lactate measurements trended downwards. The Reactance Biomarker (XL) kept showing abnormal values at the time the MAP plunged, and when the lactate measurement was taken again (1.5 hours later) the patient was under hypovolemic shock. Resuscitation attempts were made by administering norepinephrine and adrenaline but the patient passed away three hours after being admitted to the ICU.

Lactate levels are commonly evaluated in acutely ill patients. Although most commonly used in the context of evaluating shock, lactate can be elevated for many reasons [2].


Whilst lactate is a sensitive indicator of impaired oxygen utilization, it is a slow variable in terms of the time that it takes to accumulate on the blood stream to cause a readable change of concentration and in terms of the time it takes to be cleared away by the liver and the kidney once that appropriate oxygen utilization restored. Conversely, the Reactance Biomarker (XL) responds more rapidly and provides information in sharper time scales, as it detects structural changes on the tissue as they occur.