Effects Of Hemodynamics, Respiratory Mechanics And Respiratory Function In Health And Acute Lung Injury Dogs By Pressure Regulated Volume-controlled Ventilation

Objectives To study effects of hemodynamics, respiratory mechanics and respiratory function in health and acute lung injury (ALI) dogs by pressure regulated volume-controlled ventilation (PRVC) in various PEEP level and compared with intermittent positive pressure ventilation (IPPV).Methods Thirteen health hybrid dogs were randomly assigned either IPPV or PRVC modality, ventilated 30 minutes when PEEP=0, 0.5, 1.0 and 1.5kPa respectively randomly. Peak inspiration pressure(PIP),mean airway pressure (mPaw), dynamic compliance (Cdyn), cardiac output (CO), cardiac index(CI), pulmonary artery pressure (PAP), pulmonary capillary wedge pressure (PCWP), mean artery pressure (MAP),heart rate(HR), arterial and mixed venous blood sap were measured. Meanwhile, pulmonary vascular resistance (PVR), systemic vascular resistance (SVR), PaO2/FiO2, right-to-left shunt ratio (Qs/Qt), delivery of oxygen (DO2) and oxygen consumption (VO2) were calculated according to the above parameters. Acute lung injury (ALI) in dogs was induced by i.v injected oleic acid from central venous when above experiment finished. The ALI dogs were randomly assigned either IPPV or PRVC modality, ventilated 30 minutes when PEEP =0, 0.5, 1.0 and 1.5kPa respectively randomly. The measured marker was the same as those of health dogs. Results (1) Effects of PRVC and IPPV on hemodynamics In health dogs, at the same PEEP level, PVR dealed with PRVC modality was lower than that of IPPV modality except PEEP=0 kPa (p<0.05). There was no significant difference in HR, MAP, CO, CI, SVR, LVSW and RVSW. In the same ventilation modality, CO and MAP of two ventilation modalities when PEEP=1.5 kPa was lower than that of PEEP=0 kPa (p<0.05). (2) Effects of PRVC and IPPV on respiratory mechanics and respiratory function in health dogs At the same PEEP level in two ventilation modalities, PIP dealed with PRVC modality was lower than that of IPPV modality and Cdyn was higher than that of IPPV modality when PEEP=0.5 kPa (p<0.05). In the same ventilation modality, with the increase of PEEP level, PIP and mPaw of two vetilation modalities when PEEP =0.5, 1.0kPa was higher than that of PEEP=0 kPa (p<0.05), however, Cdyn only in PEEP= 0.5kPa was higher than that of PEEP=0kPa (p< 0.05). (3) Effects of PRVC and IPPV on hemodynamics in ALI dogs In the same PEEP level, There was no significant difference in all marker of hemodynamics in PRVC modality compared to IPPV.In the same ventilation modality, MAP, CO, CI, PVR and LVSW of two ventilation modalities when PEEP= 1.5 kPa was lower than that of PEEP=0 kPa (p<0.05). (4) Effects of PRVC and IPPV on respiratory mechanics and respiratory function in ALI dogs In various PEEP level, PIP dealed with PRVC modality was lower than that of IPPV (p<0.05). Cdyn was lower than that of IPPV when PEEP=0.5kPa and PEEP=1.0kPa (p<0.05). mPaw of dealed with PRVC modality was lower than that of IPPV only when PEEP=1.0kPa(p<0.05). PaO2 and PaO2/FiO2 dealed with PRVC modality was higher than those of IPPV when PEEP=0, 0.5 and 1.0 kPa (p<0.05). P(A-a)O2 and QS/Qt dealed with PRVC modality was lower than that of IPPV when PEEP=0.5 and 1.0 kPa (p<0.05).Conclusions (1) Compared to IPPV modality, PRVC modality could decrease PIP and had advantageous in decreasing the incidence of VILI; Meanwhile, PRVC modality could increase Cdyn and PaO2.But; there was no significant difference in hemodynamics between two ventilation modalities. Therefore, PRVC may be serving to treat ALI/ARDS better than IPPV. (2) PEEP could increase PIP and mPaw, with the increase of PEEP level, Qs/Qt reduced and PaO2 enhanced, meanwhile the inhibition of hemodynamics reinforced. and DO2 decreased.