Permissive Hypotension in The Extremely Low Birth Weight Infant With Signs Of Good Perfusion

Abstract

Introduction: Many practitioners routinely treat infants whose mean arterial blood pressure (BP) in mm Hg is less than their gestational age in weeks (GA).

Objective: To assess the effectiveness of utilising a combined approach of clinical signs, metabolic acidosis and absolute BP values when deciding to treat hypotension in the ELBW.

Methods: Retrospective cohort study of all live born ELBW admitted to our NICU over a 4 yr period. Patients were grouped as either normotensive (BP never less than gestational age (GA)), hypotensive and not treated (BP < GA but signs of good perfusion: this we termed permissive hypotension) and hypotensive treated (BP < GA with signs of poor perfusion).

Results: 118 patients were admitted during this time period. BP data was available on 108 patients. 53% of patients were hypotensive (mean BP in mmHg less than GA in weeks). Patients treated were of lower birth weight and GA and had significantly lower BP at 6,12,18 and 24 hrs. Normotensive patients and patients designated as having permissive hypotension have similar outcomes. Mean blood pressure in the permissive group increased from 26mmHg at 6hrs to 31mmHg at 24 hrs. In a logistic regression model, hypotension that was treated is independently associated with mortality, Odds Ratio 8.0 (95% CI 2.3, 28, p<0.001).

Conclusions: BP spontaneously improves in ELBW infants during the first 24hours. Infants hypotensive on GA criteria but had clinical evidence of good perfusion had as good an outcome as normotensive patients. Low blood pressure that was treated was associated with adverse outcome.