IN MECHANICAL VENTILATION
Medical Academy of Postgraduate Studies, St. Petersburg , Russia
Physiologic preference of spontaneous breathing over mechanical ventilation is well known. One of its motifs is stereotypic pattern of the latter in myoplegic patient, leading to time-dependent changes in lung tissue mechanics.
We proposed the algorithm of mechanical ventilation (CMV), providing continuous random changes of parameters – VT , PPEAK , TI , TPLAT , etc. – within the preset range. For example, in case of preset value VT = 500 ± 50 ml, real VT string may seem like 541, 457, 514, 485, 505 ml etc. The algorithm, available in both pressure and volume controlled CMV modes, can be easily realized by pseudorandom numbers generator in ventilator software without any changes in basic pneumatic platform design.
This option of CMV mode gives an additional advantage. In modern ventilators, static compliance (C) and resistance (R) measurement requires plateau maneuver, since P PLAT level is a borderline between R- and C-dependent components of the peak pressure equation. Randomized CMV mode could give the system of 2 equations with 2 unknowns every 2 breathing cycles – without any necessity of specific measurement maneuvers.
The first ventilator realizing these algorithms, demonstrated at X Congress of Russian anaesthesiologists ( St. Petersburg , September 2006), is now being prepared for the clinical test.