Impact of inspired gas mixtures on preoperative infants with hypoplastic left heart syndrome during controlled ventilation.

Abstract

BACKGROUND:

Management strategies for preoperative infants with hypoplastic left heart syndrome (HLHS) include increased inspired nitrogen (hypoxia) and increased inspired carbon dioxide (hypercarbia). There are no studies directly comparing these 2 therapies in humans. This study compares the impact of hypoxia versus hypercarbia on oxygen delivery, under conditions of fixed minute ventilation.

METHODS AND RESULTS:

Ten anesthetized and paralyzed preoperative infants with HLHS were evaluated in a prospective, randomized, crossover trial comparing hypoxia (17% FIO(2)) with hypercarbia (2.7% FICO(2)). Each patient was treated in a random order (10 minutes per condition) with a recovery period (15 to 20 minutes) in room air. Arterial (SaO(2)) and superior vena caval (SvO(2)) co-oximetry and cerebral oxygen saturation (ScO(2)) measurements were made at the end of each condition and recovery period. ScO(2) was measured by near infrared spectroscopy. Hypoxia significantly decreased both SaO(2) (-5.2+/-1.1%, P=0.0014) and SvO(2) (-5.6+/-1.7%, P=0.009) compared with baseline, but arteriovenous oxygen saturation (AVO(2)) difference (SaO(2)-SvO(2)) and ScO(2) remained unchanged. Hypercarbia decreased SaO(2) (-2.6+/-0.6%, P=0.002) compared with baseline but increased both ScO(2) (9.6+/-1.8%, P=0.0001) and SvO(2) (6+/-2.2%, P=0.022) and narrowed the AVO(2) difference (-8.5+/-2.3%, P=0.005). Both hypoxia and hypercarbia decreased the balance between pulmonary and systemic blood flow (Qp:Qs) compared with baseline.

CONCLUSIONS:

In preoperative infants with HLHS, under conditions of anesthesia and paralysis, although Qp:Qs falls in both conditions, oxygen delivery is unchanged during hypoxia and increased during hypercarbia. These data cannot differentiate cerebral from systemic oxygen delivery.

• Authors: S Tabbutt, C Ramamoorthy, L M Montenegro, S M Durning, C D Kurth, J M Steven, R I Godinez, T L Spray, G Wernovsky, S C Nicolson
• Journal: Circulation (Circulation) Vol. 104 Issue 12 Suppl 1 Pg. I159-64 (Sep 18 2001) ISSN: 1524-4539 [Electronic] United States
• PMID: 11568049 (Publication Type: Clinical Trial, Comparative Study, Journal Article, Randomized Controlled Trial)

Chemical References

• Carbon Dioxide
• nitrox
• Nitrogen
• Oxygen

Topics

• Administration, Inhalation
• Anesthesia
• Arteries (physiopathology)
• Blood Gas Monitoring, Transcutaneous (instrumentation)
• Brain (metabolism)
• Carbon Dioxide (administration & dosage)
• Cross-Over Studies
• Hemodynamics (drug effects)
• Humans
• Hypoplastic Left Heart Syndrome (physiopathology, therapy)
• Hypoxia (blood, chemically induced)
• Infant, Newborn
• Monitoring, Physiologic
• Nitrogen (administration & dosage)
• Oxygen (administration & dosage, analysis, metabolism)
• Preoperative Care
• Prospective Studies
• Respiration, Artificial (methods)
• Spectroscopy, Near-Infrared