Author: Shailesh Bihari
Bihari, Shailesh, 2015 Contribution of fluids and electrolyte management to lung injury, Flinders University, School of Medicine
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Introduction: Fluid administration and electrolyte management is perhaps the most common intervention done in the hospital. Acute lung injury is common in critically ill patients and is associated with increased morbidity and mortality. Current literature suggests that administration of fluids is not straightforward and there are concerns of potential harm with fluid administration. Similarly electrolyte abnormalities are known to have adverse effects in critically ill patients. This work focuses on the effects of fluid and electrolyte management on lung injury. Methods: Effects of sodium, fluid boluses and osmolality on lung injury were separately investigated. I utilised animal models, healthy human volunteers, clinical and epidemiological studies to investigate the effects of fluid and electrolyte management on lung injury Results: Sodium: Current levels of sodium administration are more than thrice the NHMRC recommendations in both adult and paediatric patients, most of which is from the inadvertent sources such drug infusions, drug boluses and flushes. Such high levels of administration leads to positive sodium balance which in turn causes an expansion of the extra cellular fluid compartment and is associated with respiratory dysfunction as evidenced by the decreased oxygen levels and prolong length of invasive mechanical ventilation. Fluid boluses: Utilizing both basic sciences and clinical studies I found that bolus administration of intravenous fluids has minimal physiological benefit and may actually be harmful. In patients with severe sepsis there was a decrease in the oxygen levels after its administration, in animals studies bolus i.v. fluids resulted in permeability pulmonary edema despite a 'safe'(non-hydrostatic) left heart pressure. Such lung injury after administration of fluid boluses is likely through activation of endothelial calcium ion channels (Transient receptor potential Valladolid 4 (TRPV4) channels. This fluid induced lung injury was prevented by administration of relatively specific TRPV4 blocker (ruthenium red). Hyperosmolality : Using animal studies I found that induced hypernatremia is lung protective in acute lung injury, independent of fluid or sodium load. Based on our animal work, we hypothesised that lung-protective effects of hypernatremia would reduce its general adverse effects, leading to amelioration of the increase in mortality risk in patients with lung injury. To confirm this we examined a large administrative database - Australia New Zealand Intensive Care Society- Centre for Outcome and Resource Evaluation (ANZICS CORE) and found that high admission serum sodium is associated with increased odds for ICU death, except in respiratory patients. Conclusions: In critically ill patients (i) inadvertent sodium administration is common which leads to a large positive sodium balance and it has adverse respiratory effects (ii) Bolus administration of fluids induces lung injury (iii) Induced hyperosmolarity is lung protective.
Keywords: Fluid,sodium,serum sodium,lung injury
Subject: Medicine thesis
Thesis type: Doctor of Philosophy
School: School of Medicine
Supervisor: Andrew D Bersten, Dani Dixon