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Effect of mechanical ventilation and volume loading on left ventricular performance in premature infants with
Insights
Mechanical ventilation in premature infants with respiratory distress syndrome reduced cardiac output. Volume loading, however, improved left ventricular performance, indicating low preload was the primary issue.
Area of Science:
- Neonatal Cardiology
- Pediatric Critical Care Medicine
- Echocardiography
Background:
- Premature infants with severe respiratory distress syndrome often require mechanical ventilation.
- Left ventricular (LV) performance can be affected by mechanical ventilation, but the underlying mechanisms require further elucidation.
Purpose of the Study:
- To assess the impact of mechanical ventilation on left ventricular (LV) performance in premature infants with severe respiratory distress syndrome.
- To determine if low preload contributes to changes in LV function during ventilation.
Main Methods:
- Echocardiography was used to measure LV size and function in 19 premature infants.
- 14 infants (group 1) were assessed before and during mechanical ventilation with positive end-expiratory pressure.
- 5 infants (group 2) received volume loading (blood transfusion) during ventilation to assess preload effects.
Main Results:
- Mechanical ventilation decreased LV dimensions, peak filling rate, stroke volume, and cardiac output in group 1.
- Systemic blood pressure remained unchanged, suggesting peripheral vasoconstriction.
- Volume loading in group 2 prevented the decline in LV filling rate and improved LV dimensions, stroke volume, cardiac output, and systolic blood pressure.
Conclusions:
- Mechanical ventilation significantly impairs left ventricular performance in premature infants with respiratory distress syndrome, primarily due to reduced preload.
- Volume loading can counteract these negative effects, highlighting the importance of maintaining adequate preload in ventilated neonates.
Abstract:
Left ventricular (LV) performance was assessed by echocardiography in 19 premature infants with severe respiratory distress syndrome. Measurements of LV size and function were made from digitized M-mode echocardiographic data in 14 babies (group 1) before and during treatment with mechanical ventilation and positive end-expiratory pressure. During ventilation, maximum LV dimension decreased (p = .001) as did peak filling rate (p = .01). LV shortening fraction decreased slightly (p = .05). There were marked reductions in calculated stroke volume (SV) (p = .001) and cardiac output (p = .0001) but systemic BP was unchanged, presumably due to peripheral vasoconstriction. The effect of simultaneous volume loading was studied in five other babies (group 2) who were ventilated under similar conditions. Blood transfusion with packed cells (10 mg/kg) prevented the fall in LV filling rate, while LV dimensions (max, p = .01; min, p = .02), SV (p = .05), cardiac output (p = .05), and systolic BP (p = .05) increased. This indicates that a low preload was responsible for the decreases observed in group 1.