Same, same but different: why absolute blood pressure values do not always provide an absolutely true picture

A 45 year old woman was hospitalised for acute, symptomatic Dengue Fever with thrombopenia. Besides body ache and pruritus, she complained of non- postural giddiness. Her blood pressure throughout was in the hypotensive range, hovering between 80- 90 mm Hg systolic and 45–65 mm Hg diastolic. This raised concerns for Dengue- virus mediated endothelial dysfunction and shock. Symptomatic swelling of hands and feet were suspicious for capillary leak syndrome, which would be a relative contraindication for crystalline volume substitution. At the same time, however, the heart rate remained bradycardic, ranging from 52- 74 beats per minute despite febrile temperatures. With incipient thrombocyte recovery, patient requested discharge but agreed to outpatient follow up. In clinic, she revealed that she had had known low blood pressure and bradycardic heart rate for all her adult life. She had been a competitive swimmer in her youth with up to 10 weekly training sessions until age 17. Given thyroid function and cortisol levels were normal, we carried out two non- invasive cardiac assessments using the NICAs device (NIMedical), which evaluates cardiac function via bioimpedance cardiography. At rest, NICAs showed hypotension (86/47 mm Hg), bradycardia 58 bpm and subnormal cardiac output (3.8 L/min) and cardiac index (2.4 L/min/m 2 ). NICAs was repeated after brief aerobic exercise (50 squats, 20 push-ups, 30 straight leg raises). This brought heart rate into the low normal range, averaging at 61bpm. Systolic blood pressure could be normalised to 92 mm Hg, but diastolic pressure remained low at 51 mm Hg. At the same time, cardiac output and cardiac index moved into the normal range at 4.0 L/min and 2.6 L/min/m 2 , respectively. While still suffering from mild giddiness, symptoms improved on exercise. While the measured absolute blood pressure values were in the hypotensive range, the patient was haemodynamically stable. The improved cardiac parameters after exercise and her personal exercise history suggest a permanent set-point to lower sympathetic drive. As such, medical alerts for this patient needed to be individually adjusted, and a personalised approach to treatment is likely to yield better outcomes. The case serves as a reminder that our guidelines are based on studies on large populations, while our patients need to be assessed as individuals if we aim to provide optimal care.