TY - JOUR

T1 - Different low constant flows can equally determine the lower inflection point in acute respiratory distress syndrome patients

AU - Casati Nogueira Gama, Ana Maria

AU - Meyer, Eduardo Correa

AU - Araújo Silva Gaudêncio, Ana Maria

AU - Andrade Grunauer, Michelle

AU - Passos Amato, Marcelo Britto

AU - Ribeiro De Carvalho, Carlos Roberto

AU - Barbas, Carmen Sílvia Valente

PY - 2001

Y1 - 2001

N2 - Among the possible techniques to obtain the pressure-volume (P × V) curve at the bedside the low constant flow (CF) is the easiest and quickest one. However, the best value for CF to perform a good semi-static P × V curve is still to be determined. The purpose of this study was to evaluate the influence of 4 different CFs (1, 2, 5, and 10 L/min) on determination of lower inflection point of the P × V curve (L-Pflex) and upper inflection point of the P × V curve (U-Pflex) on the maximum slope and on the inspiratory work of breathing (up to volume of 1.35 L; inspiratory work L/cm H2O), comparing the volume estimated from the CF with the measured volume obtained by the respiratory inductive plethysmograph. The design was a prospective study, and the setting was an adult medical intensive care unit of a university hospital. There were 7 acute respiratory distress syndrome (ARDS) patients, less than 5 days of installation, after the standardization of lung volume history received sequentially from 4 different low inspiratory CFs in 2 trials. The P × V curve lasted from 73 ± 1.6 s (1 L/min) to 8.8 ± 0.69 s (10 L/min). The L-Pflex differed in the 2 performed trials (p = 0.04). There was no difference of L-Pflex among the 4 CFs comparing the 3 methods (p = 0.072) used for its calculation as well as comparing the estimated and the measured volume (p = 0.456). The maximum slope decreased significantly while increasing the flow from 1 to 10 L/min just in the estimated volume (p = 0.03). The inspiratory work did not increase with the increment of the flow either in the estimated volume (p = 0.217) or in the measured volume (p = 0.149). The U-Pflex differed among the trials (p = 0.003) and the methods used for its calculation (p < 0.01). Constant flows from 1 to 10 L/min can equally determine L-Pflex in ARDS patients and is an easy and quick way to obtain the L-Pflex in order to optimize positive end expiratory pressure (PEEP) in ARDS patients.

AB - Among the possible techniques to obtain the pressure-volume (P × V) curve at the bedside the low constant flow (CF) is the easiest and quickest one. However, the best value for CF to perform a good semi-static P × V curve is still to be determined. The purpose of this study was to evaluate the influence of 4 different CFs (1, 2, 5, and 10 L/min) on determination of lower inflection point of the P × V curve (L-Pflex) and upper inflection point of the P × V curve (U-Pflex) on the maximum slope and on the inspiratory work of breathing (up to volume of 1.35 L; inspiratory work L/cm H2O), comparing the volume estimated from the CF with the measured volume obtained by the respiratory inductive plethysmograph. The design was a prospective study, and the setting was an adult medical intensive care unit of a university hospital. There were 7 acute respiratory distress syndrome (ARDS) patients, less than 5 days of installation, after the standardization of lung volume history received sequentially from 4 different low inspiratory CFs in 2 trials. The P × V curve lasted from 73 ± 1.6 s (1 L/min) to 8.8 ± 0.69 s (10 L/min). The L-Pflex differed in the 2 performed trials (p = 0.04). There was no difference of L-Pflex among the 4 CFs comparing the 3 methods (p = 0.072) used for its calculation as well as comparing the estimated and the measured volume (p = 0.456). The maximum slope decreased significantly while increasing the flow from 1 to 10 L/min just in the estimated volume (p = 0.03). The inspiratory work did not increase with the increment of the flow either in the estimated volume (p = 0.217) or in the measured volume (p = 0.149). The U-Pflex differed among the trials (p = 0.003) and the methods used for its calculation (p < 0.01). Constant flows from 1 to 10 L/min can equally determine L-Pflex in ARDS patients and is an easy and quick way to obtain the L-Pflex in order to optimize positive end expiratory pressure (PEEP) in ARDS patients.

KW - Acute respiratory distress syndrome

KW - Constant flow technique

KW - Mechanical ventilation

KW - Pflex

KW - Positive end expiratory pressure

KW - Pressure-volume curves

UR - http://www.scopus.com/inward/record.url?scp=0035667384&partnerID=8YFLogxK

U2 - 10.1046/j.1525-1594.2001.06898.x

DO - 10.1046/j.1525-1594.2001.06898.x

M3 - Artículo

C2 - 11903141

AN - SCOPUS:0035667384

SN - 0160-564X

VL - 25

SP - 882

EP - 889

JO - Artificial Organs

JF - Artificial Organs

IS - 11

ER -