[Mean airway pressure during pressure-controlled ventilation with static vs. dynamic positive end-expiratory pressure].
BACKGROUND
Positive end-expiratory pressure increases mean airway pressure (Paw) in patients with mechanical ventilation. We undertook this study to compare mean airway pressure (Paw) generated with static PEEP (sPEEP) vs. dynamic PEEP (dPEEP) at the same level of total PEEP (tPEEP) in the same patient with pressure-controlled mechanical ventilation (PC).


METHODS
We conducted a prospective clinical trial at the Intensive Care Unit of a university-affiliated hospital. Consecutive patients in PC with SaO2>90%; FiO2<50%; sPEEP of 4 cm H2O and inspiration-expiration ratio (I:E ratio) 1:2 were included in the study. After a basal period of time of 15 min, Paw was registered (phase one of the study protocol). In phase 2 with the ventilator settings constant, only the I:E ratio was switched to 2:1 to generate dPEEP, and after 15 min Paw and total PEEP (tPEEP) were registered (tPEEP=sPEEP+dPEEP). In phase 3, the I:E ratio was switched back to 1:2 substituting the dPEEP generated in the second phase of the study by sPEEP to maintain the same level of tPEEP of phase 2. After 15 min, Paw was again registered. Friedman and Wilcoxon's test were used, p value<0.05 was considered statistically significant.


RESULTS
Thirty eight patients were admitted to the study protocol, tPEEP was 4, 8 and 8 cm H2O and median of the Paw 8.7, 13.8, and 11.4 cm H2O, respectively, with a p value<0.05 in the first, second and third phases of the study.


CONCLUSIONS
During pressure control ventilation, mean airway pressure is affected by the level of total PEEP and its composition. Paw is higher when dynamic PEEP participates in the composition of total PEEP.
León-Gutiérrez
Marco Antonio
MA
Facultad de Medicina, Universidad Nacional Autónoma de México, and Unidad de Cuidados Intensivos y Medicina Crítica, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, IMSS, Huixquilucan, Estado de México, México.
Castañón-González
Jorge Alberto
JA
Lázaro-Castillo
Eugenio E
EE
Pech-Quijano
Jorge Alfredo
JA
Abraján-Hernández
Octavio Iván
OI
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011312:Pressure; D011446:Prospective Studies; D015656:Respiratory Mechanics / Q000502:physiology*