ABSTRACT
Objective To investigate the effects of 3 different ventilation methods,including conventional mechanical ventilation(CMV),high-frequency oscillatory ventilation(HFOV) and partial liquid ventilation(PLV),on the morphology of type Ⅱ alveolar epithelium cell (ACE Ⅱ) of newborn piglet with acute lung injury (ALI).Methods Twenty-four less than 3-day-old newborn piglets were enrolled.After ALI was established with saline lavage (38 ℃,0.035 L/kg),newborn piglets were randomly assigned to 4 study groups:control group(n =6,no ventilation),CMV group(n =6),HFOV group(n =6),and PLV group(n =6,38 ℃,0.018 L/kg).Piglets in the 4 groups were sacrificed after being ventilated for 24 hours,and the number,area,density of fluorescence of ACE Ⅱ were detected.Results Through 24 hours mechanical ventilation,the numbers of ACE Ⅱ in CMV group,HFOV group and PLV group remained were 30 ± 5,52 ± 5,81 ± 7,respectively,while areas of fluorescence were 340.40 ± 47.50,329.69 ± 124.50,295.55 ± 109.30,respectively,and there were significant differences among the 3 groups,and the population mean of density of fluorescence had significant difference among the 3 groups.The number of ACE Ⅱ remains was lowest in CMV group compared with HFOV group(P =0.026) and PLV group (P =0.000),and the density of fluorescence of ACE Ⅱ was lowest in CMV group compared with HFOV group (P =0.001) and PLV group (P =0.002).Conclusions Different mechanical ventilations have various effects for ACE Ⅱ,and CMV is the most harmful mechanical ventilation on ACE Ⅱ,while PLV is the least harmful.
ABSTRACT
OBJECTIVE: Evaluation of myocardial histological changes in an experimental animal model of neonatal hypoxiareoxygenation. METHODS: Normocapnic hypoxia was induced in 40 male Landrace/Large White piglets. Reoxygenation was initiated when the animals developed bradycardia (HR <60 beats/min) or severe hypotension (MAP <15 mmHg). The animals were divided into four groups based on the oxygen (O2) concentration used for reoxygenation; groups 1, 2, 3, and 4 received 18%, 21%, 40%, and 100% O2, respectively. The animals were further classified into five groups based on the time required for reoxygenation: A: fast recovery (<15 min); B: medium recovery (15-45 min); C: slow recovery (45-90 min); D: very slow recovery (>90 min), and E: nine deceased piglets. RESULTS: Histology revealed changes in all heart specimens. Interstitial edema, a wavy arrangement, hypereosinophilia and coagulative necrosis of cardiomyocytes were observed frequently. No differences in the incidence of changes were observed among groups 1-4, whereas marked differences regarding the frequency and the degree of changes were found among groups A-E. Coagulative necrosis was correlated with increased recovery time: this condition was detected post-asphyxia in 14%, 57%, and 100% of piglets with fast, medium, and slow or very slow recovery rates, respectively. CONCLUSIONS: The significant myocardial histological changes observed suggest that this experimental model might be a reliable model for investigating human neonatal cardiac hypoxia-related injury. No correlation was observed between the severity of histological changes and the fiO2 used during reoxygenation. Severe myocardial changes correlated strictly with recovery time, suggesting an unreported individual susceptibility of myocardiocytes to hypoxia, possibly leading to death after the typical time-sequence of events.