In mechanical ventilation for status asthmaticus, a lung protective strategy directed at reducing dynamic hyperinflation must be used, with low tidal volumes and long expiratory times. Pressure regulated volume control is a dual mode with tidal volume is feedback control for continuously adjusting pressure control. On the other hand pressure control is a fixed pressure in each breath with no target tidal volume.
Objective: To compare between the two modes (PC and VC+) regarding clinical, gasometric and ventilatory response in patients with status asthmaticus.
Patients& methods: Fourty intubated patients (21males and 19 females) with status asthmaticus were studied. The patients had been mechanically ventilated with puritan Bennett, 840 ventilator. They are divided into two groups: G1: Submitted to PC, and G2: Submitted to VC+.
Results: Both groups were comparable regarding demographic, clinical, gasometric, and laboratory data. The successful outcome was recorded in 75% of patients in G1, versus 80 % in G2. There was a significant (P<0.05) improvement in RR, pH, PaCO2, PaO2after 1hour of mechanical ventilation in both groups, with significantly better improvement for pH & PaCO2 in G2.In successful outcome there was a significant (P<0.05) lower end inspiratory pressure inG2 (21.6 ±2.1 vs 27 ± 0.9 in G1), lower auto PEEP in G2 (3.3 ±0.7 vs 5.2 ± 1.0 in G1), and decrease of missing efforts in G2 (0.9 ±0.6 vs 1.7 ± 0.5 in G1) after 6hours ventilation. Also Tidal volume revealed a significant (P<.001) higher values in G2 (394 ±33 vs 330 ± 28 in G1) after 1 hour ventilation. In both groups, auto PEEP showed significant positive correlation(r=0.916; P<0.001in G1 and r=0.872; P<0.001 ) with number of missing efforts.
Conclusion: VC+ offers better minute ventilation, lower inspiratory pressure, less homodynamic compromise and is more comfortable than pressure control for intubated patients with status asthmaticus.