Static versus dynamic respiratory mechanics for setting the ventilator.

Lichtwarck-Aschoff, M; Kessler, V; Sjöstrand, U H; Hedlund, A; Mols, G; Rubertsson, S; Markström, A M; Guttmann, J · Br J Anaesth · 2000

basic_science · Level V

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Abstract

The lower inflection point (LIP) of the inspiratory limb of a static pressure-volume (PV) loop is assumed to indicate the pressure at which most lung units are recruited. The LIP is determined by a static manoeuvre with a PV-history that is different from the PV-history of the actual ventilation. In nine surfactant-deficient piglets, information to allow setting PEEP and VT was obtained, both from the PV-curve and also during ongoing ventilation from the dynamic compliance relationship. According to LIP, PEEP was set at 20 (95% confidence interval 17-22) cm H2O. Volume-dependent dynamic compliance suggested a PEEP reduction (to 15 (13-18) cm H2O). Pulmonary gas exchange remained satisfactory and this change resulted in reduced mechanical stress on the respiratory system, indirectly indicated by volume-dependent compliance being consistently great during the entire inspiration.

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