Elsevier

Journal of Pediatric Surgery

Volume 40, Issue 9, September 2005, Pages 1395-1403
Journal of Pediatric Surgery

Original article
Relationship among cardiac index, inspiration/expiration ratio, and perfluorocarbon dose during partial liquid ventilation in an oleic acid model of acute lung injury in sheep,

https://doi.org/10.1016/j.jpedsurg.2005.05.038Get rights and content

Abstract

Background

The aim of this study was to demonstrate the influence of different inspiration/expiration (I/E) ratios on cardiac index (CI) and hemodynamics during partial liquid ventilation (PLV) using a large animal model of acute respiratory failure in a prospective, randomized controlled animal laboratory trial.

Methods

After induction of respiratory failure by right atrial injection of 0.09 mL/kg oleic acid, (1) determination of agreement between reversed Fick and pulmonary artery thermodilution (QTD) techniques with progressive doses of perflubron (LiquiVent, Alliance Pharmaceutical Corp, San Diego, Calif) (n = 7 sheep) and (2) comparison of 4 groups with I/E ratios of 3.4:1, 2:1, 1:1, and 1:2 were performed, applying identical ventilatory patterns in all I/E groups (n = 28 sheep). PLV was established with intratracheal instillation of 25 mL/kg perflubron. Cardiac index was assessed at 15-minute intervals for a 120-minute experimental period by QTD.

Results

During progressive doses of PLV, the correlation (r) between Fick and QTD techniques was 0.82. Thermodilution deteriorated after induction of lung injury and recovered after PLV start. Regarding QTD, no significant changes after PLV onset (within-group comparison) and between I/E groups were observed (P < .05).

Conclusion

The QTD technique is a satisfactory reflector of CI during PLV, and I/E ratio has no significant influence on CI, even using extreme inverse ratio ventilation.

Section snippets

Animal preparation

After review and approval by the Regierungspräsidium Karlsruhe, Germany, the study was carried out as a prospective, randomized controlled trial in the animal laboratories of the Klinikum Mannheim University Medical Center. University of Heidelberg guidelines for the use and care of animals were followed throughout. After intramuscular premedication with 2 mL Xylazin (Rompun 2%, Bayer Leverkusen, Germany), anesthesia was started by intravenous injection of 3 mg/kg ketamine (Ketanest,

Fick and QTD techniques comparison

In a total of 98 simultaneous measurements, mean QTD was 1.40 ± 0.07 L/min · m2 and mean QFick was 1.51 ± 0.06 L/min · m2. Correlation between techniques was r = 0.82 and Bland-Altman analysis revealed variation reliability between techniques with a mean difference of 0.21 ± 0.15 L/min · m2 (Fig. 1). However, the paired samples t test revealed significant differences between techniques at P = .001. Progressive doses of perflubron stepwise from 10 to 40 mL/kg had no significant influence on the

Discussion

At induction of acute lung injury, PEEP was set to and maintained at 12 cm H2O based on the results of previous studies in oleic-acid injured sheep during PLV [25]. It was shown that PEEP of more than 12 cm H2O is sufficient to maintain airway pressures above the lower inflection point (LIP) of the pressure-volume curve [13]. All other ventilatory parameters besides I/E ratio were kept constant among all investigational groups.

Improvements in pulmonary parameters during perfluorocarbon PLV in

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    This study was supported in part by departmental funds of the Klinikum Mannheim University Medical Center. Perflubron was generously provided by the Alliance Pharmaceutical Corp, San Diego, Calif.

    This work is attributed to and was performed at the Animal Research Laboratories, Universitätsklinikum Mannheim, Fakultät für klinische Medizin der Universität Heidelberg, Mannheim, Germany. This study was presented in part at the 1999 meeting of the European Society of Intensive Care Medicine [Int Care Med. 1999;25(suppl 1):199].

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