Neonatal Med.  2013 Feb;20(1):42-50. 10.5385/nm.2013.20.1.42.

The Time When the Metabolic Compensation for Hypercapnia Begin to Occur in Very Low Birth Weight Infants

• Lee JM
• Kim C
• Kim YJ
• Shin SH
• Lee J
• Sohn JA
• Sohn SH
• Choi GY
• Lee JA
• Park HW
• Choi CW
• Kim EK
• Kim HS
• Kim BI
• Choi JH

• KMID: 2052454
• DOI: http://doi.org/10.5385/nm.2013.20.1.42

Abstract

PURPOSE
Lung injury from mechanical ventilation is one of the major pathogenetic factors of bronchopulmonary dysplasia. Permissive hypercapnia (PH) is one of the strategies for reducing lung injury. However, PH is frequently infeasible in very low birth weight infants (VLBWI) due to their immature renal compensation for respiratory acidosis. The purpose of this study was to identify time when metabolic compensation for hypercapnia begin to occur in VLBWIs.
METHODS
Data were retrospectively collected from 82 VLBWI who were admitted to Seoul National University Bundang Hospital from January 2011 to December 2012. The postnatal day when the difference between actual bicarbonate and expected bicarbonate levels became less than 2.0 mmol/L consistently for the first time under hypercapnea (>40 mmHg) was defined as the time when metabolic compensation for hypercapnea occurred.
RESULTS
Metabolic compensation for hypercapnea occurred on 9.1+/-3.9 postnatal day. The younger the gestational age (GA) was and the smaller the birth weight was, the later metabolic compensation for hypercapnea occurred. Late metabolic compensators (> or =9 days) were significantly younger in GA (P=0.001), lighter at birth (P=0.041), intubated longer (P=0.002), and less frequently afflicted with respiratory distress syndrome (P=0.036) compared to early metabolic compensators (<9 days). However, logistic regression analysis revealed only young GA was associated with late metabolic compensation with marginal significance (P=0.068).
CONCLUSION
Metabolic compensation for hypercapnea occurred 9 days after birth on average. PH strategy for reducing lung injury should be considered after renal metabolic compensation for hypercapnea occurs in VLBWI.

Keyword

Permissive hypercapnia; Metabolic compensation; Very low birth weight infants

MeSH Terms

Acidosis, Respiratory
Birth Weight
Bronchopulmonary Dysplasia
Compensation and Redress
Gestational Age
Humans
Hydrogen-Ion Concentration
Hypercapnia
Infant
Infant, Newborn
Infant, Very Low Birth Weight
Logistic Models
Lung Injury
Parturition
Respiration, Artificial
Retrospective Studies