Effects of different interventions for early-stage acute lung injury on respiratory response and work of breathing in canine model / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effects of different interventional strategies, namely controlled high-concentration oxygen therapy, continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP) ventilation, on respiratory response and work of breathing (WOB) in canine models of early-stage acute lung injury (ALI).</p><p><b>METHODS</b>After successful duplication of ALI models with oleic acid (diagnostic criteria: Pa(O2)/Fi(O2)<or=300 mmHg), 24 adult mongrel dogs were randomized into 3 equal groups for treatment with controlled high-concentration oxygen therapy (O2), CPAP, and BiPAP, respectively. The parameters of respiratory response and WOB were recorded continuously at the baseline, early-stage ALI, and 1-4 hours after treatment.</p><p><b>RESULTS</b>BiPAP resulted in the most significant effects in reducing the respiratory rate (RR) and f/V(T) (P<0.001), followed by CPAP and O2 interventions (P<0.001). None of the 3 treatments showed obvious effects on V(E) (P>0.05), which maintained the level of early ALI/ARDS stage. BiPAP greatly improved V(T) and V(T)/Ti, showing better effects than CPAP and O2. No significant differences were noted among the 3 groups in T(I)/T(tot) (P>0.05). BiPAP showed superior effect to CPAP in lowering the peak transdiaphragmatic pressure (Pdi). CPAP and BiPAP both effectively counteracted intrinsic positive end expiratory pressure (PEEPi) (P<0.01), while O2 produced no obvious such effects (P>0.05). BiPAP showed the most evident effects, followed by CPAP, in reducing WOB, but oxygen therapy produced no obvious effects. CPAP (P<0.01) and BiPAP (P>0.05) both effectively reduced the proportion of ingredients in WOB related to PEEPi.</p><p><b>CONCLUSION</b>BiPAP and CPAP can produce favorable effects in relieving dyspnea, reducing WOB and improving respiratory response to control the deterioration of ARDS. BiPAP has more significant therapeutic effects than CPAP and oxygen therapy.</p>

Assessment of early-stage physiological response to acute lung injury in canine models using balloon catheter system for measuring esophageal and gastric pressure / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore feasible and reliable methods for estnbolishment and of acute lung injury model in animal models.</p><p><b>METHODS</b>Twenty-four healthy adult mongrel dogs with oleic acid-induced acute lung injury were evaluated for early-stage physiological response to acute lung injury using a balloon catheter system for measuring esophageal and gastric pressure.</p><p><b>RESULTS</b>In canine models of early-stage oleic acid-induced acute lung injury that sustained spontaneous breathing, in terms of respiratory mechanics, some parameters obviously increased including the respiratory rate (RR), minute ventilation (VE), peak inspiratory volume (Vinsp, peak), mean inspiratory volume (VT/Ti), inspiratory airway resistance (Raw, insp) (P<0.001 for all the parameters), with also significantly increased peak transdiaphragmatic pressure (Pdi, peak, P=0.0185). The tidal volume (VT) and dynamic lung compliance (CL,dyn), however, were significantly decreased (P<0.001), and significant variation occurred in the ratio of inspiratory time to duration of one breath (Ti/Ttot, P=0.163). In terms of gas exchange, the pH, PaO(2), SaO(2), PaO(2)/FiO(2), and end tidal partial pressure of carbon dioxide (PETCO(2)) all evidently declined (P<0.001), but PaCO(2) and ratio of alveolar dead space to tidal volume [VD(alv)/VT] increased significantly (P<0.001).</p><p><b>CONCLUSION</b>Application of balloon catheter system for measuring esophageal and gastric pressures allows objective evaluation of the various physiological responses in early stage of acute lung injury.</p>