The Science Journal of the American Association for Respiratory Care

1999 OPEN FORUM Abstracts

PARTIAL LIQUID VENTILATION: HISTOLOGIC AND MORPHEMETRIC DIFFERENCES BETWEEN FRC AND LOW DOSE AMOUNTS WITH EXOGENOUS SURFACTANT.

Patricia A. Meyers RRT, JM Manaligod MD, EM Bendel-Stenzel MD, DR Bing RRT, SC Simonton MD, MC Mammel MD. Infant Pulmonary Research Center, Children's Hospital-St. Paul, Minnesota and Dept. Of Pediatrics, University of Minnesota, Mpls, MN.

Introduction: Partial liquid ventilation (PLV) using FRC amounts of perflubron (LiquiVentÒ), exogenous surfactant (SurvantaÒ; S) and high frequency ventilation (HFV) have each been reported to cause less barotrauma in lung injured animals and humans. Does low dose PLV provide the same amount of protection? We evaluated histology and morphometry in 32 newborn piglets with saline lavage induced lung injury. Method: 32 newborn piglets were sedated, paralyzed, and ventilated using a volume target of 12cc/kg. We induced lung injury, defined as PaO2<60 torr at FiO2 1.0 and lung compliance reduction by >30%. After stabilization on conventional ventilation (CV, Dräger BabylogÒ), we randomized animals to 4 groups of 8 each: CV+S+PLV to FRC(28.5±5.7 mL/kg), HFV (SensorMedics 3100)+S, HFV+S+low PLV (10 mL/kg) and HFV+S+PLV to FRC(27.5±6.8mL/kg) and ventilated for 20 hrs. PLV animals had perfluorocarbon instilled intratracheally. Evaporative loss were replaced hourly by assessing meniscus in ET tube, HFV+S+low PLV received 3ml/kg/hr replacement. Ventilators were adjusted as in clinical use. Lungs were excised en block, inflated to 30 cm H2O pressure and fixed in 10% formalin. We scored alveolar and interstitial inflammation and hemorrhage, edema, atelectasis, necrosis, and presence of hyaline membranes on a 0=none to 4=100% involvement scale, for right and left upper and lower lobes. Upper and lower lobes were scored separately, then summed. Scores were analyzed using the Kruskal-Wallis test. We assessed group differences with the Newman-Keuls test.

Table 1: Histology, mean and total injury scores, upper (u) and lower (l) lobes

Mean (u) total (u) mean (l) total (l)
CV+S+PLV 0.45 3.63 0.36 2.88
HFV+S 0.88* 7.00* 0.95* 7.63*
HFV+S+lo PLV 0.40 3.19 0.32 2.56
HFV+S+PLV 0.36 2.88 0.30 2.38

Table 2; Morphometry, mean %tissue area and squared root of variance

% area (u) var. (u) % area (l) var. (l)
CV+S+PLV 33.96 10.66 29.21 9.06
HFV+S 49.11* 16.39* 58.05* 15.23*
HFV+S+lo PLV 28.79 13.00 30.70 11.11
HFV+S+PLV 27.23 9.85 31.72 10.31
* HFV+S is different from CV+S+PLV, HFV+S+lo PLV, and HFV+S+PLV(p<.022), ?HFV+S is different from CV+S+PLV, and HFV+S+lo PLV (p=.024)

Conclusion: Lung injury was similar in the PFC treated groups. HFV+S+low PLV resulted in similar injury, as the groups which received FRC amounts PFC. HFV+S resulted in more injury when compared to the PFC treated groups.

OF-99-018

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