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AuthorsManu L.N.G. Malbrain
Introduction and background
Preload and fluid responsiveness are two different things. In certain situations like patients with increased intrathoracic pressures, traditional barometric filling pressures as the central venous pressure are erroneously increased. In those circumstances volumetric preload indices better reflect the true preload conditions of the patient. Fluid management in these patients can be very tricky because adequate early initial resuscitation is mandatory however in order to prevent organ edema and secondary abdominal hypertension one must avoid ongoing futile fluid loading. We will illustrate opposite changes between barometric and volumetric preload indices in a patient with increased intrathoracic pressure.
Patients and methods
The case of a 26 year old man admitted to the ICU after general seizures described. This case was presented at the 32nd annual international symposium on intensive care and emergency medicine (ISICEM) in Brussels on March 20th and at the 2nd International Fluid Academy Day (IFAD) in Antwerp on November 17th.
In this patient, that developed shock within 18 hours of ICU admission the dynamic evolution is presented. Despite initial normal (and thus adequate) filling pressures, further fluid resuscitation was needed to overcome the ebb phase (this was guided by functional hemodynamic parameters and volumetric preload indices). Diuretics were initiated after 24 hours to help the patient to transgress to the flow phase because of respiratory failure due to capillary leak as evidenced by increased extravascular lung water.
This case nicely demonstrates the biphasic clinical course from ebb to flow during shock as well as the inability of traditional filling pressures to guide us through these different phases. It also provides answers to the four basic but crucial questions that need to be solved in order not to do any harm to the patient: (1) when do I start giving fluids, (2) when do I stop giving fluids, (3) when do I start to empty my patient, and finally ( 4) when do I stop emptying?