Susan C. Simonton

Prolonged partial liquid ventilation using conventional and high-frequency ventilatory techniques: gas exchange and lung pathology in an animal model of respiratory distress syndrome.

OBJECTIVE To evaluate the effect of prolonged partial liquid ventilation with perflubron (partial liquid ventilation), using conventional and high-frequency ventilatory techniques, on gas exchange, hemodynamics, and lung pathology in an animal model of lung injury. DESIGN Prospective, randomized, controlled study. SETTING Animal laboratory of the Infant Pulmonary Research Center, Childrens Health Care-St. Paul. SUBJECTS Thirty-six newborn piglets. INTERVENTIONS We studied newborn piglets with lung injury induced by saline lavage. Animals were randomized into one of five treatment groups: a) conventional gas ventilation (n = 8); b) partial liquid ventilation with conventional ventilation (n = 7); c) partial liquid ventilation with high-frequency jet ventilation (n = 7); d) partial liquid ventilation with high-frequency oscillation (n = 7); and e) partial liquid ventilation with high-frequency flow interruption (n = 7). After induction of lung injury, all partial liquid ventilation animals received intratracheal perflubron to approximate functional residual capacity. After 30 mins of stabilization, animals randomized to high-frequency ventilation were changed to their respective high-frequency modes. Hemodynamics and blood gases were measured before and after lung injury, after perflubron administration, and then every 4 hrs for 20 hrs. Histopathologic evaluation was carried out using semiquantitative scoring and computer-assisted morphometric analysis on pulmonary tissue from animals surviving at least 16 hrs. MEASUREMENTS AND MAIN RESULTS All animals developed acidosis and hypoxemia after lung injury. Oxygenation significantly (p < .001) improved after perflubron administration in all partial liquid ventilation groups. After 4 hrs, oxygenation was similar in all ventilator groups. The partial liquid ventilation-jet ventilation group had the highest pH; intergroup differences were seen at 16 and 20 hrs (p < .05). The partial liquid ventilation-oscillation group required higher mean airway pressure; intergroup differences were significant at 4 and 8 hrs (p < .05). Aortic pressures, central venous pressures, and heart rates were not different at any time point. Survival rate was significantly lower in the partial liquid ventilation-flow interruption group (p < .05). All partial liquid ventilation-treated animals had less lung injury compared with gas-ventilated animals by both histologic and morphometric analysis (p < .05). The lower lobes of all partial liquid ventilation-treated animals demonstrated less damage than the upper lobes, although scores reached significance (p < .05) only in the partial liquid ventilation-conventional ventilation animals. CONCLUSIONS In this animal model, partial liquid ventilation using conventional or high-frequency ventilation provided rapid and sustained improvements in oxygenation without adverse hemodynamic consequences. Animals treated with partial liquid ventilation-flow interruption had a significantly decreased survival rate vs. animals treated with the other studied techniques. Histopathologic and morphometric analysis showed significantly less injury in the lower lobes of lungs from animals treated with partial liquid ventilation. High-frequency ventilation techniques did not further improve pathologic outcome.

Urological Aspects of Sacrococcygeal Teratoma in Children

Sacrococcygeal teratoma is the most common extragonadal germ cell tumor of infancy. Associated urological complications, most of which are reported in children with malignancy, include vesicoureteral reflux, ureteral and urethral obstruction, and neurogenic bladder. To evaluate the influence of tumor grade and type on adverse urological outcome we reviewed the charts of 29 children with sacrococcygeal teratoma and correlated urological problems to lesion type and grade. No correlation was noted between tumor grade and the incidence of urological complications. The most common urological complications were neurogenic bladder in 12% of the patients, ureteral obstruction in 10% and vesicoureteral reflux in 7%. The highest incidence of urological complications (81%) was seen in patients with type IV (presacral) disease. We recommend early radiographic and neurourodynamic evaluation in all children with sacrococcygeal teratoma.

Perfluorocarbon priming and surfactant: physiologic and pathologic effects.

OBJECTIVE To test the hypothesis that perfluorocarbon (PFC) priming before surfactant administration improves gas exchange and lung compliance, and also decreases lung injury, more than surfactant alone. DESIGN Prospective, randomized animal study. SETTING Animal research laboratory of Childrens Hospital of St. Paul. SUBJECTS Thirty-two newborn piglets, weighing 1.55 +/- 0.18 kg. INTERVENTIONS We studied four groups of eight animals randomized after anesthesia, paralysis, tracheostomy, and establishment of lung injury using saline washout to receive one of the following treatments: a) surfactant alone (n = 8); b) priming with the PFC perflubron alone (n = 8); c) priming with perflubron followed by surfactant (n = 8); and d) no treatment (control; n = 8). Perflubron priming was achieved by instilling perflubron via the endotracheal tube in an amount estimated to represent the functional residual capacity, ventilating the animal for 30 mins, and then removing perflubron by suctioning. After all treatments were given, animals were mechanically ventilated for 4 hrs. MEASUREMENTS AND MAIN RESULTS We evaluated oxygenation, airway pressures, respiratory system compliance, and hemodynamics at baseline, after induction of lung injury, and at 30-min intervals for 4 hrs. Histopathologic evaluation was carried out using a semiquantitative scoring system and by computer-assisted morphometric analysis. After all treatments, animals had decreased oxygenation indices (p < .001) and increased respiratory system compliance (p < .05). Animals in PFC groups had similar physiologic responses to treatments as animals treated with surfactant only; both the PFC-treated groups and the surfactant-treated animals required lower mean airway pressures throughout the experiment (p < .001) and had higher pH levels at 90 and 120 mins (p < .05) compared with the control group. Pathologic analysis demonstrated decreased lung injury in surfactant-treated animals compared with animals treated with PFC or the controls (p < .02). CONCLUSIONS Priming the lung with PFC neither improved the physiologic effects of exogenous surfactant nor improved lung pathology in this animal model.

Surfactant and partial liquid ventilation via conventional and high-frequency techniques in an animal model of respiratory distress syndrome.

Objective To compare the physiologic and pathologic effects of conventional ventilation (CV) and high-frequency ventilation (HFV) during partial liquid ventilation (PLV) with perflubron after surfactant treatment with the results of HFV plus surfactant in an animal lung-injury model created by saline lavage. We also studied the dose effects of perflubron during HFV. Design Randomized experimental study. Setting Research animal laboratory. Subjects A total of 32 newborn piglets. Interventions After lung injury was induced, the animals were randomized to one of four groups: a) CV + surfactant + perflubron to functional residual capacity (FRC); b) HFV + surfactant + perflubron to FRC; c) HFV + surfactant + 10 mL/kg perflubron; and d) HFV + surfactant. All then received intratracheal surfactant. After 30 mins, perflubron was administered to the PLV groups. The animals underwent ventilation for 20 hrs. Measurements and Main Results Arterial blood gases and hemodynamic variables were continuously monitored. Pulmonary histologic and morphometric analyses were performed after death or euthanasia at 20 hrs. All animals had sustained improvements in arterial/alveolar oxygen ratios, and no differences were observed among groups. All HFV groups required higher mean airway pressures to maintain oxygenation (p < .05). Hemodynamics did not differ among groups. Pathologic analysis demonstrated decreased lung injury in both cranial-dorsal (nondependent) and caudal-ventral (dependent) lobes of all animals treated with PLV when compared with those treated with HFV + surfactant (p < .05). Conclusions After surfactant treatment, physiologic support over 20 hrs was similar during HFV with or without perflubron and CV with perflubron. All PLV modalities improved lung pathologic factors uniformly to a greater degree than did HFV + surfactant. A lower treatment volume of perflubron during HFV produced physiologic and pathologic results similar to those produced by perflubron with respect to FRC during either CV or HFV.

PARTIAL LIQUID VENTILATION VS GAS VENTILATION: HISTOLOGIC DIFFERENCES USING HIGH FREQUENCY AND CONVENTIONAL TECHNIQUES. † 2083

PARTIAL LIQUID VENTILATION VS GAS VENTILATION: HISTOLOGIC DIFFERENCES USING HIGH FREQUENCY AND CONVENTIONAL TECHNIQUES. † 2083

High Frequency Oscillatory and Conventional Ventilation, Exogenous Surfactant, and Partial Liquid Ventilation: Physiologic Effects of Prolonged Treatment in an Animal Lung Injury Model

High Frequency Oscillatory and Conventional Ventilation, Exogenous Surfactant, and Partial Liquid Ventilation: Physiologic Effects of Prolonged Treatment in an Animal Lung Injury Model

High Frequency Oscillatory and Conventional Ventilation, Exogenous Surfactant, and Partial Liquid Ventilation: Effect of Prolonged Treatment on Lung Pathology in an Animal Lung Injury Model

High Frequency Oscillatory and Conventional Ventilation, Exogenous Surfactant, and Partial Liquid Ventilation: Effect of Prolonged Treatment on Lung Pathology in an Animal Lung Injury Model

Exogenous Surfactant during Partial Liquid Ventilation: Lung Pathology.† 1550

Surfactant (surf, Survanta®) followed by partial liquid ventilation(PLV) with perflubron (LiquiVent®) improves lung mechanics and oxygenation more than S only, PLV only, or PLV followed by S (Peds Res 1996:39;343A). Histologic and morphometric analysis was performed on slides from the upper anterior and lower posterior lobes of 32 newborn piglets (1.7±0.8 kg) with saline lavage-induced lung injury (PaO2<60 torr, FiO2 1.0) after randomization into 4 groups and treatment for 2 hours with: 1) surf only (S; n=8); 2) PLV only (PLV; n=8); 3) PLV followed by surf (PLV-S; n=8 and 4) surf followed by PLV (S-PLV; n=8). Ventilators were adjusted to maintain tidal volume of 15 cc/kg; FiO2 was 1.0. Histologic variables (alveolar, interstitial inflammation; alveolar, interstitial hemorrhage; edema; atelectasis; necrosis) were scored on a 0-4 point scale (no injury = 0, injury in 25% of field = 1, injury in 50% of field = 2, injury in 75% of field = 3, and injury throughout field = 4). Morphometric analysis on trichrome-stained slides analyzed total cellular to air space, expressed as percent tissue area (% tissue area =[cellular area/total area] × 100). Kruskal-Wallis, Wilcoxin, and paired t-tests with Bonferroni correction (p<0.05) were used to assess differences. Table