scholarly journals 1686 CHANGES IN MEAN AIRWAY PRESSURE: SIGNIFICANCE IN NEONATAL AIRLEAK SYNDROME

1981 ◽  
Vol 15 ◽  
pp. 724-724 ◽  
Author(s):  
Millard A Litzenberger ◽  
H Douglas Cunningham ◽  
Nirmala S Desai ◽  
Jacqueline A Noonan
Keyword(s):  
Airway Pressure ◽  
Mean Airway Pressure

scholarly journals Evaluation of a Humidified Nasal High-Flow Oxygen System, Using Oxygraphy, Capnography and Measurement of Upper Airway Pressures

2011 ◽  
Vol 39 (6) ◽  
pp. 1103-1110 ◽  
Author(s):  
J. E. Ritchie ◽  
A. B. Williams ◽  
C. Gerard ◽  
H. Hockey
Keyword(s):  
Healthy Volunteers ◽  
Airway Pressure ◽  
Gas Flow ◽  
Air Entrainment ◽  
High Flow ◽  
Positive Pressure ◽  
Mean Airway Pressure ◽  
Flow Rates ◽  
Oxygen Fraction ◽  
Airway Pressures

In this study, we evaluated the performance of a humidified nasal high-flow system (Optiflow™, Fisher and Paykel Healthcare) by measuring delivered FiO2 and airway pressures. Oxygraphy, capnography and measurement of airway pressures were performed through a hypopharyngeal catheter in healthy volunteers receiving Optiflow™ humidified nasal high flow therapy at rest and with exercise. The study was conducted in a non-clinical experimental setting. Ten healthy volunteers completed the study after giving informed written consent. Participants received a delivered oxygen fraction of 0.60 with gas flow rates of 10, 20, 30, 40 and 50 l/minute in random order. FiO2, FEO2, FECO2 and airway pressures were measured. Calculation of FiO2 from FEO2 and FECO2 was later performed. Calculated FiO2 approached 0.60 as gas flow rates increased above 30 l/minute during nose breathing at rest. High peak inspiratory flow rates with exercise were associated with increased air entrainment. Hypopharyngeal pressure increased with increasing delivered gas flow rate. At 50 l/minute the system delivered a mean airway pressure of up to 7.1 cmH2O. We believe that the high gas flow rates delivered by this system enable an accurate inspired oxygen fraction to be delivered. The positive mean airway pressure created by the high flow increases the efficacy of this system and may serve as a bridge to formal positive pressure systems.

Estimation of Mortality Risk in Chronically Ventilated Infants With Bronchopulmonary Dysplasia

PEDIATRICS ◽  
1991 ◽  
Vol 88 (6) ◽  
pp. 1153-1160 ◽  
Author(s):  
Debora W. Overstreet ◽  
J. Craig Jackson ◽  
Gerald van Belle ◽  
William E. Truog
Keyword(s):  
Mechanical Ventilation ◽  
Bronchopulmonary Dysplasia ◽  
Airway Pressure ◽  
Life Support ◽  
Water Pressure ◽  
Accurate Estimation ◽  
Regression Equations ◽  
Bacterial Sepsis ◽  
Mean Airway Pressure ◽  
Predictors Of Mortality

Bronchopulmonary dysplasia is a chronic, sometimes fatal lung disease, which primarily affects premature infants and often leads to a dependence on mechanical ventilation lasting many months. To identify prognostic factors of mortality at 1 and 2 months of age, the authors reviewed the medical records of the 144 neonates admitted to two neonatal intensive care units in Seattle from January 1, 1986, through December 31, 1988, who required mechanical ventilation throughout the first month of life. Likely predictors of mortality were tested by logistic regression analysis. The calculated mean airway pressure at 30 days of age (MAP30) and the diagnosis of bacterial sepsis at any time during the first month of life (Bact0-30) were statistically significant predictors of mortality (P < .001 and P = .018, respectively) and had the lowest deviance in the regression model. The probability of mortality was estimated by 1/(1 + e-x, where x = -6.510 + 0.4588 (MAP30) + 1.475 (Bact0-30), and where MAP30 is expressed as centimeters of water pressure (1 cm H2O = 0.0978 kPa) and the presence or absence of bacteremia is 1 and 0, respectively. The records of the 57 infants who still required mechanical ventilation at 60 days of age were reanalyzed with clinical data available during the first 2 months of life. Mean airway pressure (MAP60) and the fraction of inspired oxygen (F60) at 60 days of age combined to form the best predictors of mortality, where x = -7.668 + 0.2940 (MAP60) + 5.935 (F60). The occurrence of bacterial sepsis during the first 2 months of life, the degree of hypochloremia, and the duration of chronic sedative use were also significant predictors of survival, even controlling of MAP60 and F60. These regression equations allow more accurate estimation of the likelihood of survival for chronically ventilated infants and may facilitate decisions regarding withdrawal or continuation of life support.

Effect of the Ti/Te ratio on mean intratracheal pressure in high-frequency oscillatory ventilation

1998 ◽  
Vol 84 (5) ◽  
pp. 1520-1527 ◽  
Author(s):  
Ulrich Thome ◽  
Frank Pohlandt
Keyword(s):  
High Frequency ◽  
Airway Pressure ◽  
High Frequency Oscillatory Ventilation ◽  
Inspiratory Time ◽  
Mean Airway Pressure ◽  
Air Trapping ◽  
Oscillatory Ventilation ◽  
Mean Pressure ◽  
Oscillation Frequencies ◽  
High Frequency Oscillatory

In high-frequency oscillatory ventilation (HFOV), an adequate mean airway pressure is crucial for successful ventilation and optimal gas exchange, but air trapping cannot be detected by the usual measurement at the y piece. Intratracheal pressures produced by the high-frequency oscillators HFV-Infantstar (IS), Babylog 8000 (BL), and the SensorMedics 3100A (SM) [the latter with either 30% (SM30) or 50% (SM50) inspiratory time] were investigated in four anesthetized tracheotomized female piglets that were 1 day old and weighed 1.6–1.9 kg (mean 1.76 kg). The endotracheal tube was repeatedly clamped while the piglets were ventilated with an oscillation frequency of 10 Hz, and the airway pressure distal of the clamp was recorded as a measure of average intrapulmonary pressure during oscillation. Clamping resulted in a significant decrease of mean airway pressure when the piglets were ventilated with SM30(−0.86 cmH2O), BL (−0.66 cmH2O), and IS (−0.71 cmH2O), but airway pressure increased by a mean of 0.76 cmH2O with SM50. Intratracheal pressure, when measured by a catheter pressure transducer at various oscillation frequencies, was lower than at the y piece by 0.4–0.9 cmH2O (SM30), 0.3–3 cmH2O (BL), and 1–4.7 cmH2O (IS) but was 0.4–0.7 cmH2O higher with SM50. We conclude that the inspiratory-to-expiratory time (Ti/Te) ratio influences the intratracheal and intrapulmonary pressures in HFOV and may sustain a mean pressure gradient between the y piece and the trachea. A Ti/Te ratio < 1:1 may be useful to avoid air trapping when HFOV is used.

scholarly journals MEAN AIRWAY PRESSURE (MAP) DURING HIGH FREQUENCY FLOW INTERRUPTION (HFFI).1979

1996 ◽  
Vol 39 ◽  
pp. 332-332
Author(s):  
Wil Geven ◽  
Dianne Visser ◽  
Jeroen Hopman ◽  
Desiree Cremers ◽  
Margot van de Bor
Keyword(s):  
High Frequency ◽  
Airway Pressure ◽  
Mean Airway Pressure ◽  
Flow Interruption

Setting Mean Airway Pressure during High-frequency Oscillatory Ventilation According to the Static Pressure–Volume Curve in Surfactant-deficient Lung Injury

2003 ◽  
Vol 99 (6) ◽  
pp. 1313-1322 ◽  
Author(s):  
Thomas Luecke ◽  
Juergen P. Meinhardt ◽  
Peter Herrmann ◽  
Gerald Weisser ◽  
Paolo Pelosi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Lung Volume ◽  
High Frequency ◽  
Airway Pressure ◽  
Static Pressure ◽  
High Frequency Oscillatory Ventilation ◽  
Mean Airway Pressure ◽  
Oscillatory Ventilation ◽  
Hemodynamic Variables ◽  
High Frequency Oscillatory

Background Numerous studies suggest setting positive end-expiratory pressure during conventional ventilation according to the static pressure-volume (P-V) curve, whereas data on how to adjust mean airway pressure (P(aw)) during high-frequency oscillatory ventilation (HFOV) are still scarce. The aims of the current study were to (1) examine the respiratory and hemodynamic effects of setting P(aw) during HFOV according to the static P-V curve, (2) assess the effect of increasing and decreasing P(aw) on slice volumes and aeration patterns at the lung apex and base using computed tomography, and (3) study the suitability of the P-V curve to set P(aw) by comparing computed tomography findings during HFOV with those obtained during recording of the static P-V curve at comparable pressures. Methods Saline lung lavage was performed in seven adult pigs. P-V curves were obtained with computed tomography scanning at each volume step at the lung apex and base. The lower inflection point (Pflex) was determined, and HFOV was started with P(aw) set at Pflex. The pigs were provided five 1-h cycles of HFOV. P(aw), first set at Pflex, was increased to 1.5 times Pflex (termed 1.5 Pflex(inc)) and 2 Pflex and decreased thereafter to 1.5 times Pflex and Pflex (termed 1.5 Pflex(dec) and Pflex(dec)). Hourly measurements of respiratory and hemodynamic variables as well as computed tomography scans at the apex and base were made. Results High-frequency oscillatory ventilation at a P(aw) of 1.5 Pflex(inc) reestablished preinjury arterial oxygen tension values. Further increase in P(aw) did not change oxygenation, but it decreased oxygen delivery as a result of decreased cardiac output. No differences in respiratory or hemodynamic variables were observed when comparing HFOV at corresponding P(aw) during increasing and decreasing P(aw). Variation in total slice lung volume (TLVs) was far less than expected from the static P-V curve. Overdistended lung volume was constant and less than 3% of TLVs. TLVs values during HFOV at Pflex, 1.5 Pflex(inc), and 2 Pflex were significantly greater than TLVs values at corresponding tracheal pressures on the inflation limb of the static P-V curve and located near the deflation limb. In contrast, TLVs values during HFOV at decreasing P(aw) (i.e., 1.5 Pflex(dec) and Pflex(dec)) were not significantly greater than corresponding TLV on the deflation limb of the static P-V curves. The marked hysteresis observed during static P-V curve recordings was absent during HFOV. Conclusions High-frequency oscillatory ventilation using P(aw) set according to a static P-V curve results in effective lung recruitment, and slice lung volumes during HFOV are equal to those from the deflation limb of the static P-V curve at equivalent pressures.

Association Between Neonatal Care Practices and Efficacy of Exogenous Human Surfactant: Results of a Bicenter Randomized Trial

PEDIATRICS ◽  
1993 ◽  
Vol 91 (3) ◽  
pp. 552-560
Author(s):  
Mikko Hallman ◽  
T. Allen Merritt ◽  
Kristina Bry ◽  
Charles Berry
Keyword(s):  
Airway Pressure ◽  
Fluid Intake ◽  
Ductus Arteriosus ◽  
Neonatal Care ◽  
Mean Airway Pressure ◽  
Oxygen Requirement ◽  
Good Outcome ◽  
Surfactant Substitution ◽  
Care Practices ◽  
The Impact

The purpose of this study was to analyze the impact of neonatal care practices on the efficacy of exogenous human surfactant. Two hundred newborns (gestational age 24.0 to 29.9 weeks, lecithin-sphingomyelin ratio less than 2 or absent phosphatidylglycerol, and requirement of mechanical ventilation at birth) participated in a randomized bicenter trial of human surfactant substitution. In only one of the two sites (site 2) surfactant substitution decreased the severity of respiratory failure and increased neonatal survival without bronchopulmonary dysplasia. For analysis of three-way association, continuous variables describing patient characteristics and treatment were dichotomized at the median. The following variables were significantly associated with good outcome in site 1 and 2 and with surfactant substitution in site 2: low oxygen requirement during first three neonatal days, low mean airway pressure during second and third day, low Paco2 during first two neonatal days, and no ligation of ductus arteriosus. Low fluid intake during the first three days and low colloid intake during the first two days of life were associated with good outcome in both sites. The ratio between mean airway pressure and the oxygen requirement was higher in site 2 than in site 1 during the first day of life. Fluid intake and ventilatory management may influence the efficacy of exogenous surfactant.

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