FUNCTIONAL RESIDUAL CAPACITY AND VENTILATORY PRESURES DURING POSITIVE-PRESSURE VENTILATION AT HIGH FREQUENCIES

We have used a rapid-freeze method to stop mechanical changes in the living lung in 0-10 sec and have adapted histological techniques to prepare thick three-dimensional sections from which diameters of alveoli and alveolar ducts were determined for lungs at two volumes, functional residual capacity and high lung volume, during positive-pressure ventilation. Diameters of both alveoli and ducts increase 30% from the lower to the higher lung volume. The calculated surface area of alveoli increases 70%. The volumes of alveoli and ducts were calculated to increase about twofold. The ventilation unit of the lung includes the alveolar ducts with their associated alveoli stemming from one respiratory bronchiole. The distribution of inspired gas to the respiratory surface of the lung is not determined by hundreds of millions of individual alveoli but by these larger ventilation units. Submitted on September 5, 1961

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Effect of position and positive pressure ventilation on functional residual capacity in morbidly obese patients: a randomized trial

Canadian Journal of Anesthesia/Journal canadien d anesthésie ◽

10.1007/s12630-018-1050-1 ◽

2018 ◽

Vol 65 (5) ◽

pp. 522-528 ◽

Cited By ~ 4

Author(s):

Etienne J. Couture ◽

Steeve Provencher ◽

Jacques Somma ◽

François Lellouche ◽

Simon Marceau ◽

...

Keyword(s):

Randomized Trial ◽

Functional Residual Capacity ◽

Positive Pressure Ventilation ◽

Positive Pressure ◽

Morbidly Obese ◽

Obese Patients ◽

Residual Capacity

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Lung interdependence and lung-chest wall interaction of sublobar and lobar units in pigs

Journal of Applied Physiology ◽

10.1152/jappl.1979.46.1.8 ◽

1979 ◽

Vol 46 (1) ◽

pp. 8-13 ◽

Cited By ~ 5

Author(s):

A. Zidulka ◽

J. T. Sylvester ◽

S. Nadler ◽

N. R. Anthonisen

Keyword(s):

Chest Wall ◽

Positive Pressure Ventilation ◽

Esophageal Pressure ◽

Positive Pressure ◽

Elastic Recoil ◽

Lung Unit ◽

Residual Capacity ◽

Diaphragmatic Motion ◽

Wall Interaction ◽

The Right

In anesthetized and paralyzed pigs in the left decubitus position we obstructed, at functional residual capacity (FRC), either the right middle and lower lobes, or a small posterior basal lung unit, and then passively inflated the unobstructed remaining lung. Measurements were made of alveolar pressure in the obstructed and unobstructed lung regions as well as of esophageal pressure. The tendency of the obstructed lung region to inflate as the remainder of the lung was inflated was assessed by an index (A), which was the end-inspiratory pressure difference between unobstructed and obstructed alveolar pressures, normalized by the change in elastic recoil of unobstructed lung. With the chest wall intact, inflation of unobstructed lung resulted in a tendency to inflate the obstructed regions. This tendency was abolished with the chest wall removed. In a second group of pigs with the basilar lung unit obstructed, the height of the unit was changed by turning a pig from right to left decubitus positions. In each position A was assessed with both spontaneous and positive pressure ventilation. The magnitude of A was found to vary directly with the magnitude of caudal diaphragmatic motion and was greatest with the lung unit dependent and with spontaneous ventilation. These results suggest that lung-chest wall interaction was a more important factor tending to preserve homogenous inflation than lung tissue interdependence.

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Short- and Intermediate-Term Outcomes of Preterm Infants Receiving Positive Pressure Ventilation in the Delivery Room

Critical Care Research and Practice ◽

10.1155/2013/715915 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Megan O'Reilly ◽

Po-Yin Cheung ◽

Khalid Aziz ◽

Georg M. Schmölzer

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Neonatal Intensive Care ◽

Positive Pressure Ventilation ◽

Survival Rates ◽

Delivery Room ◽

Positive Pressure ◽

Protective Strategy ◽

Residual Capacity ◽

Ventilation Strategies

Although recent advances in neonatal care have improved survival rates, rates of bronchopulmonary dysplasia remain unchanged. Although neonatologists are increasingly applying gentle ventilation strategies in the neonatal intensive care unit, the same emphasis has not been applied immediately after birth. A lung-protective strategy should start with the first breath to help in the establishment of functional residual capacity, facilitate gas exchange, and reduce volutrauma and atelectotrauma. This paper will discuss techniques and equipment during breathing assistance in the delivery room.

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From Continuous Positive-pressure Breathing to Ventilator-induced Lung Injury

Anesthesiology ◽

10.1097/00000542-200410000-00028 ◽

2004 ◽

Vol 101 (4) ◽

pp. 1015-1017 ◽

Cited By ~ 4

Author(s):

Henning Pontoppidan ◽

Srinivasa N. Raja

Keyword(s):

Respiratory Failure ◽

Acute Respiratory Failure ◽

Positive Pressure Ventilation ◽

Arterial Oxygen Tension ◽

Intermittent Positive Pressure Ventilation ◽

Arterial Oxygen ◽

Positive Pressure ◽

Residual Capacity ◽

The Mean ◽

Continuous Positive Pressure

Continuous positive-pressure ventilation in acute respiratory failure. By Kumar A, Falke KJ, Geffin B, Aldredge CF, Laver MB, Lowentein E, Pontoppidan H. N Engl J Med 1970; 283:1430-6. Reprinted with permission. Continuous positive-pressure ventilation was used in eight patients with severe acute respiratory failure. Cardiac output and lung function were studied during continuous positive-pressure ventilation (mean end-expiratory pressure, 13 cm H2O) and a 30-min interval of intermittent positive-pressure ventilation. Although the mean cardiac index increased from 3.6 to 4.5 l/min per square meter of body surface area, the mean intrapulmonary shunt increased by 9% with changeover to intermittent positive-pressure ventilation. Satisfactory oxygenation was maintained in all patients during continuous positive-pressure ventilation with 50% inspired oxygen or less. With intermittent positive-pressure ventilation, arterial oxygen tension promptly fell by 161 mm of mercury, 79% occurring within 1 min. Prevention of air-space collapse during expiration and an increase in functional residual capacity probably explain improved oxygenation with continuous positive-pressure ventilation. In four patients, subcutaneous emphysema or pneumothorax developed. Weighed against the effects of prolonged hypoxemia, these complications were not severe enough to warrant cessation of continuous positive-pressure ventilation.

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