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Efficacy of high frequency ventilation combined with volume controlled ventilation in dependency of extravascular lung water
Author(s) -
Zeravik J.,
Pfeiffer U. J.
Publication year - 1989
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1989.tb02968.x
Subject(s) - medicine , anesthesia , ventilation (architecture) , cardiac index , mean airway pressure , mechanical ventilation , oxygenation , vascular resistance , hemodynamics , oxygenation index , stroke volume , cardiac output , tidal volume , arterial blood , respiratory system , blood pressure , heart rate , mechanical engineering , engineering
In a prospective study continuous positive pressure ventilation (CPPV) was compared with the combination of CPPV and high frequency ventilation (CHFV). Forty‐seven patients of a surgical intensive care unit who required mechanical ventilation were randomly assigned to a CHFV group (n = 27) or a control group with CPPV (n=20). Usual hemodynamic and oxygenation variables, intrathoracic blood volume (ITBV) and extravascular lung water (ETV) were assessed before and 6 h after switching to CHFV (CHFV group) or maintaining CPPV (control group). In both groups mean airway pressure (MPaw) was kept constant. The change of the respiratory index (dRI) was used for evaluation of the effect of the ventilation mode. A negative correlation was found between ETV and dRI (r= –0.67), which led to the conclusion that the height of ETV determines the efficacy of CHFV. In a CHFV subgroup with ETV > 15 ml/kg (n= 17), CHFV significantly improved Pao 2 /Fio 2 (18.7 to 26.4 kPa), RI (4.44 to 2.99) and intrapulmonary shunt (33.5 to 27.5%) and slightly, but significantly impaired cardiac index (CI, 4.45 to 3.92 l/min · m 2 ), stroke volume index (40.7 to 36.4 ml/m 2 ) and pulmonary vascular resistance index (PVRI, 310 to 366 dyn · s · cm ‐5 · m 2 ), but oxygen delivery (Do 2 ) remained almost unchanged. The CI decrease came about with an increase of PVRI on account of an increased lung volume under CHFV in this group. CHFV induced no significant effects in the subgroup with ETV < 15 ml/kg (n=10). There were no differences in any variable during CPPV between the CHFV subgroups and corresponding subgroups of the control group. In conclusion, ETV helps to identify patients in whom CHFV markedly improves oxygenation. In these patients CHFV also slightly decreases CI, if MPaw is kept constant. However, the CI decrease is outweighed by the improvement of oxygenation, as Do 2 remains unchanged.