Dimensional responses of bronchi in apneic dogs to airway pressure, gases and drugs

1960 ◽  
Vol 15 (2) ◽  
pp. 229-234 ◽  
Author(s):  
Kaye H. Kilburn
Keyword(s):  
Carbon Dioxide ◽  
Negative Pressure ◽  
Airway Pressure ◽  
Morphological Changes ◽  
Positive Pressure ◽  
Yield Data ◽  
Consistent Effect ◽  
Airway Pressures ◽  
The Right

To quantitate in vivo the morphological changes produced in bronchial dimensions by various stimuli, 42 sets of bronchograms were made of the right lungs of 23 anesthetized mongrel dogs. The effects of gases and drugs on bronchial length and width were estimated by comparing the bronchograms made at similar airway pressures with control bronchograms without these agents. Negative pressure, acetylcholine, histamine, 5-hydroxytryptamine (serotonin) and 5% carbon dioxide narrow bronchial segments. Positive pressure, atropine and isoproterenol widen and, to a lesser degree, lengthen them. Theophylline ethylenediamine (aminophyllinè) lacks a consistent effect on dimensions. Modifications of these techniques in man might yield data of value in differentiating bronchial abnormalities in patients with normal inspiratory bronchograms. Submitted on November 5, 1959

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.

scholarly journals Oxygen and Carbon Dioxide Transport Characteristics of the Blood of the Nile Monitor Lizard (Varanus Niloticus)

1987 ◽  
Vol 130 (1) ◽  
pp. 27-38
Author(s):  
JAMES W. HICKS ◽  
ATSUSHI ISHIMATSU ◽  
NORBERT HEISLER
Keyword(s):  
Carbon Dioxide ◽  
Haemoglobin Concentration ◽  
Oxygen Affinity ◽  
Total Blood ◽  
Carbon Dioxide Transport ◽  
Monitor Lizard ◽  
The Right ◽  
Dissociation Curves

Oxygen and carbon dioxide dissociation curves were constructed for the blood of the Nile monitor lizard, Varanus niloticus, acclimated for 12h at 25 and 35°C. The oxygen affinity of Varanus blood was low when Pco2 w a s in the range of in vivo values (25°C: P50 = 34.3 at PCOCO2 = 21 mmHg; 35°C: P50 = 46.2 mmHg at PCOCO2 = 35 mmHg; 1 mmHg = 133.3 Pa), and the oxygen dissociation curves were highly sigmoidal (Hill's n = 2.97 at 25°C and 3.40 at 35°C). The position of the O2 curves was relatively insensitive to temperature change with an apparent enthalpy of oxygenation (ΔH) of −9.2kJ mol−1. The carbon dioxide dissociation curves were shifted to the right with increasing temperature by decreasing total CCOCO2 at fixed PCOCO2, whereas the state of oxygenation had little effect on total blood CO2 content. The in vitro buffer value of true plasma (Δ[HCO3−]pl/-ΔpHpl) rose from 12.0 mequiv pH−1−1 at 25°C to 17.5 mequiv pH−11−1 at 35°C, reflecting a reversible increase of about 30% in haemoglobin concentration and haematocrit levels during resting conditions in vivo.

In Vivo Visualization of Intracardiac Structures With Gaseous Carbon Dioxide

1956 ◽  
Vol 186 (2) ◽  
pp. 325-334 ◽  
Author(s):  
M. J. Oppenheimer ◽  
T. M. Durant ◽  
H. M. Stauffer ◽  
G. H. Stewart ◽  
P. R. Lynch ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Body Position ◽  
Left Heart ◽  
Mortality And Morbidity ◽  
X Ray ◽  
Carbon Dioxide Gas ◽  
Great Vessels ◽  
Gaseous Carbon Dioxide ◽  
The Right

Carbon dioxide gas was injected a) intravenously, b) into the left heart, c) into the peripheral end of the carotid artery. Resulting cardiovascular and respiratory changes were observed by cinefluorography and by measurements of pressure pulses in various locations. Blood and respiratory gas changes were also observed. All changes were minimal (seconds duration) when the gas was introduced on the right or left side of the circulation. Injection into the peripheral carotid produced no untoward effects. The gas gave good visualization of valves and great vessels. Body position was not an important factor in mortality and morbidity when carbon dioxide was the gas used for contrast visualization by a cinefluorography x-ray technique. Carbon dioxide is a safe contrast medium to use for in vivo study of intracardiac structures. The gas has been used successfully by intravenous injection in human cases.

Indomethacin compromises hemodynamics during positive-pressure ventilation, independently of prostanoids

1993 ◽  
Vol 74 (4) ◽  
pp. 1672-1678 ◽  
Author(s):  
D. D. Malcolm ◽  
J. L. Segar ◽  
J. E. Robillard ◽  
S. Chemtob
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Cerebral Blood Flow ◽  
Airway Pressure ◽  
Regional Blood Flow ◽  
Blood Gases ◽  
Positive Pressure ◽  
Organ Blood Flow ◽  
Mean Airway Pressure ◽  
Airway Pressures

We examined whether prostanoids contribute to the impaired cardiac function and decrease in regional blood flow induced by increasing mean airway pressure. Using microspheres, we measured cardiac output and major organ blood flow and assayed prostaglandin E2, 6-ketoprostaglandin F1 alpha, and thromboxane B2 in blood at mean airway pressures of 5–25 cmH2O in mechanically ventilated newborn piglets treated with ibuprofen (40 mg/kg, n = 6), indomethacin (0.3 mg/kg, n = 6), or vehicle (n = 6). Blood gases and pH were stable throughout the experiments. Prostanoid levels remained constant with increasing mean airway pressure in vehicle-treated pigs and were unchanged by indomethacin. However, ibuprofen decreased the prostanoid levels at all mean airway pressures studied (P < 0.01). As ventilatory pressure was progressively increased, cardiac output decreased gradually and similarly by 42–45% (P < 0.05) in all groups. At the highest mean airway pressure, blood flow decreased to the kidneys by 37–57%, to the ileum by 58–74%, and to the colon by 53–71% (P < 0.05) in all groups. Cerebral blood flow remained constant at all ventilatory pressures regardless of the treatment. There was no difference in cardiac output and regional hemodynamics between ibuprofen- and vehicle-treated animals. However, after indomethacin, ileal blood flow at the higher ventilatory pressures was 41–46% lower and cerebral blood flow at all mean airway pressures was 14–25% lower than after the other treatments (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Systemic Air Embolism Associated with Pleural Pigtail Chest Tube Insertion

2016 ◽  
Vol 2016 ◽  
pp. 1-3
Author(s):  
Emad Alkhankan ◽  
Ahmad Nusair ◽  
Rida Mazagri ◽  
Mohammed Al-Ourani
Keyword(s):  
Airway Pressure ◽  
Positive Pressure Ventilation ◽  
Positive Airway Pressure ◽  
Rare Complication ◽  
Air Embolism ◽  
Positive Pressure ◽  
Pigtail Catheter ◽  
Tube Insertion ◽  
Systemic Air Embolism ◽  
The Right

Pleural pigtail catheter placement is associated with many complications including pneumothorax, hemorrhage, and chest pain. Air embolism is a known but rare complication of pleural pigtail catheter insertion and has a high risk of occurrence with positive pressure ventilation. In this case report, we present a 50-year-old male with bilateral pneumonia who developed a pneumothorax while on mechanical ventilation with continuous positive airway pressure mode. During the placement of the pleural pigtail catheter to correct the pneumothorax, the patient developed a sudden left sided body weakness and became unresponsive. An air embolism was identified in the right main cerebral artery, which was fatal.

Continuous Positive Airway Pressure

PEDIATRICS ◽  
1972 ◽  
Vol 49 (3) ◽  
pp. 468-469
Author(s):  
Peter A. M. Auld ◽  
Alfred N. Krauss ◽  
David B. Klain
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Negative Pressure ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Clinical Course ◽  
Lower Extremities ◽  
Hyaline Membrane Disease ◽  
Positive Pressure ◽  
Hyaline Membrane ◽  
Intermittent Positive Pressure Breathing

The recent enthusiastic report of the use of continuous positive airway pressure (CPAP) prompts us to report our own experience with this method of therapy in infants with severe hyaline membrane disease. In 1968, four severely affected infants with hyaline membrane disease were treated with CPAP. The therapy was undertaken in infants whose clinical course was deteriorating under intermittent positive pressure breathing. The CPAP was applied by a negative pressure chamber that enclosed a child's chest, abdomen, and lower extremities.

Unilateral pulmonary edema in rabbits after reexpansion of collapsed lung

1979 ◽  
Vol 46 (1) ◽  
pp. 31-35 ◽  
Author(s):  
J. Pavlin ◽  
F. W. Cheney
Keyword(s):  
Pulmonary Edema ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Rabbit Model ◽  
Dry Weight ◽  
Pleural Space ◽  
Positive Pressure ◽  
Unilateral Pulmonary Edema ◽  
Reexpansion Pulmonary Edema ◽  
The Right

The effects of the mode of reinflation and of the duration of prior collapse on the development of unilateral pulmonary edema following reexpansion of collapsed lung were studied in a rabbit model simulating the human syndrome of “reexpansion pulmonary edema.” The right lungs of rabbits were maintained in an atelectatic state for 0.5 h to 8 days, by injection of air into the pleural space. Reexpansion was achieved in 2 h by application of positive pressure to the airway while a chest tube was connected to underwater seal, or by application of negative pressure (-20 to -100 Torr) to a screened window in the partietal pleura. The lung surface pressures we actually applied by the two methods are not known. Animals were then killed and pulmonary edema was determined by wet-to-dry weight ratios. The incidence of unilateral pulmonary edema increased as the duration of prior collapse was increased (85% after 7--8 days; 17% after 3 days; and 0% after 0,5 h) when reinflated with -100 Torr applied to the pleural window. Although the incidence was less, it also occurred following the use of pleural window pressure less negative than -100 Torr, and after reinflation by positive airway pressure.

scholarly journals Comparison of airway pressures and expired gas washout for nasal high flow versus CPAP in child airway replicas

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Kelvin Duong ◽  
Michelle Noga ◽  
Joanna E. MacLean ◽  
Warren H. Finlay ◽  
Andrew R. Martin
Keyword(s):  
Carbon Dioxide ◽  
Airway Pressure ◽  
High Flow ◽  
Nasal Airway ◽  
Lung Simulator ◽  
Airway Pressures ◽  
Obstructive Sleep ◽  
Tracheal Pressure ◽  
Expired Gas ◽  
End Tidal

Abstract Background For children and adults, the standard treatment for obstructive sleep apnea is the delivery of continuous positive airway pressure (CPAP). Though effective, CPAP masks can be uncomfortable to patients, contributing to adherence concerns. Recently, nasal high flow (NHF) therapy has been investigated as an alternative, especially in CPAP-intolerant children. The present study aimed to compare and contrast the positive airway pressures and expired gas washout generated by NHF versus CPAP in child nasal airway replicas. Methods NHF therapy was investigated at a flow rate of 20 L/min and compared to CPAP at 5 cmH2O and 10 cmH2O for 10 nasal airway replicas, built from computed tomography scans of children aged 4–8 years. NHF was delivered with three different high flow nasal cannula models provided by the same manufacturer, and CPAP was delivered with a sealed nasal mask. Tidal breathing through each replica was imposed using a lung simulator, and airway pressure at the trachea was recorded over time. For expired gas washout measurements, carbon dioxide was injected at the lung simulator, and end-tidal carbon dioxide (EtCO2) was measured at the trachea. Changes in EtCO2 compared to baseline values (no intervention) were assessed. Results NHF therapy generated an average positive end-expiratory pressure (PEEP) of 5.17 ± 2.09 cmH2O (mean ± SD, n = 10), similar to PEEP of 4.95 ± 0.03 cmH2O generated by nominally 5 cmH2O CPAP. Variation in tracheal pressure was higher between airway replicas for NHF compared to CPAP. EtCO2 decreased from baseline during administration of NHF, whereas it increased during CPAP. No statistical difference in tracheal pressure nor EtCO2 was found between the three high flow nasal cannulas. Conclusion In child airway replicas, NHF at 20 L/min generated average PEEP similar to CPAP at 5 cm H2O. Variation in tracheal pressure was higher between airway replicas for NHF than for CPAP. The delivery of NHF yielded expired gas washout, whereas CPAP impeded expired gas washout due to the increased dead space of the sealed mask.

scholarly journals Positive Airway Pressure at Extubation Minimizes Subglottic Secretion Leak In Vitro

2022 ◽  
Vol 11 (2) ◽  
pp. 307
Author(s):  
Tzu-Pei Wang ◽  
Hsin-Hsien Li ◽  
Hui-Ling Lin
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Endotracheal Tube ◽  
Negative Pressure ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Positive Pressure ◽  
Subglottic Secretion ◽  
Pressure Setting ◽  
Lower Volume

Accumulated secretion above the endotracheal tube cuff can be aspirated during extubation after deflation. The possible techniques for minimizing pulmonary aspiration from subglottic secretion during extubation have not been well explored. This study aimed to determine the effect of different extubation techniques on secretion leakage. An endotracheal tube was placed in a tube mimicking an airway. We measured the leak volume of water or artificial sputum of different viscosities with three extubation techniques—negative pressure with suctioning; positive pressure with a resuscitator; and continuous positive airway pressure set at 5, 10, and 20 cm H2O. Extubation with continuous positive airway pressure resulted in lower secretion leakage than that with negative pressure with suctioning and positive pressure with a resuscitator. Increasing the continuous positive airway pressure level decreased secretion leakage volume during extubation. We further determined a correlation of leak volume with sputum viscosity. Continuous positive airway pressure at 5 cm H2O produced lower volume secretion leakage than the other two techniques, even with higher secretion viscosity. Based on these results, using continuous positive airway pressure with a previous ventilator continuous positive airway pressure/positive end-expiratory pressure setting for extubation is recommended.

Sign in / Sign up

Export Citation Format

Share Document