From the Journals

New analysis challenges fluid resuscitation guidelines for patients in shock


 

FROM THE LANCET RESPIRATORY MEDICINE

Although guideline recommended, treating children in shock with a bolus of saline or albumin fluid imposes counterproductive effects on respiratory and neurologic function, ultimately increasing risk of death, according to a detailed analysis of available data, including a randomized trial.

Several sets of guidelines for resuscitation of patients in shock have advocated volume expansion with bolus intravenous fluid, but that recommendation was based on expected physiologic benefits not a randomized trial. The only randomized trial associated this approach showed increased mortality, and a new analysis of these and other data appears to explain why.

According to the findings of a study lead by Michael Levin, MD, of the department of medicine at Imperial College London and colleagues, “volume resuscitation is associated with deterioration of respiratory function and neurological function in some patients.” Their study was published in Lancet Respiratory Medicine. The authors stated that saline-induced hyperchloremic acidosis appears to have been “a major contributor” to the observed increase in adverse outcomes.

The key take home message is that “normal saline and other unbuffered crystalloid solutions should be avoided in resuscitating seriously ill patients,” according to the authors, who believe the findings might be relevant to adults as well as children.

The controversy about the role of volume expansion for management of shock was ignited by a 2011 trial called FEAST (N Engl J Med. 2011;364:2483-95). That trial, which randomized African children with severe febrile illness to a bolus of 20-40 mg of 5% albumin solution, a bolus of 0.9% saline solution, or no bolus, was halted early when 48-hour mortality data showed a lower death rate in the no bolus group (7.3%) than either the albumin (10.6%) or saline (10.5%) bolus groups.

The FEAST result was unexpected and so contrary to accepted thinking that it prompted widespread debate, including whether findings in the resource-poor area of the world where the FEAST trial was conducted could be extrapolated to centers elsewhere in the world. Arguing for benefit, fluid resuscitation is known to increase pulse pressure and urinary output. Arguing against benefit, pulmonary edema is a known complication of bolus fluid replacement.

In an attempt to address and potentially resolve this controversy, data collected in the FEAST trial along with four other sets of data involving volume expansion in critically ill children were evaluated with a focus on changes in cardiovascular, neurological, and respiratory function. Analysis of blood biochemistry and blood oxygen transport were also conducted.

The cardiovascular, respiratory, and neurologic functions were scored on the basis of objective measurements, such as heart rate, respiratory rate, and blood pressure. These measures were evaluated prior to fluid administration and at 1 hour, 4 hours, 8 hours, 24 hours, and 48 hours after fluid administration. Odds ratio (OR) of an adverse outcome were evaluated in the context of each 10-unit change in these scores.

Relative to baseline, there was worsening respiratory and neurological function after fluid administration. Although cardiovascular function improved, hemoglobin concentrations were lower in those who received fluid than in those who did not. Fluid resuscitation was also associated with lower bicarbonate and increased base deficit and chloride at 24 hours.

Regression modeling with physiological variables suggests “that the increased mortality in FEAST can be explained by bolus-induced worsening in respiratory and neurological function, hemodilution, and hyperchloremic acidosis,” according to the authors.

Analyses of the four other sets of data, which included children treated for meningococcal sepsis in the United Kingdom, acutely ill with malaria treated in Malawi, and cohorts of children in South Africa and a London hospital for acute illnesses, provided supportive data.

Although this analysis does not address the value of administering buffered solutions in low volumes, the authors concluded that the data from the FEAST trial are generalizable. They challenge the routine use of bolus infusions of saline or albumin in the initial management of shock, which has been guideline recommended. The risks of fluid resuscitation might be particularly high among children who already have compromised respiratory or neurologic function.

SOURCE: Levin M et al. Lancet Respir Med. 2019;7:581-93.

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