scholarly journals The Effects of Three Manual Hyperinflation Techniques on Pattern of Ventilation in a Test Lung Model

2002 ◽  
Vol 30 (3) ◽  
pp. 283-288 ◽  
Author(s):  
L. Maxwell ◽  
E. R. Ellis
Keyword(s):  
Airway Pressure ◽  
Lung Model ◽  
Peak Airway Pressure ◽  
Treatment Technique ◽  
Valve Closure ◽  
Test Lung ◽  
Flow Rates ◽  
Pair Comparisons ◽  
Expiratory Flow Rates ◽  
Circuit Configuration

Manual hyperinflation (MHI) is used by physiotherapists as a treatment technique in intubated patients. This study investigated the effect of three different MHI techniques using a Mapleson-C circuit configuration with a CIG Medishield valve on volume delivered (Vt), peak inspiratory (PIFR) and expiratory flow rates (PEFR), and peak airway pressure (PAP) in a test lung model. The protocols differed in the degree of valve closure and inclusion of an inspiratory pause. For protocols 1, 2 and 3 the measures were Vt—1.33 (0.21), 2.74 (0.13), 3.55 (0.12) litres; PAP— 14.30 (0.82), 24.00 (0.47), 30.20 (0.92) cmH 2 O and PIFR—1.13 (0.05), 1.51 (0.15), 1.32 (0.09) l/s respectively. All pair comparisons were statistically significant except for PEFR (l/s), which was significantly lower for protocol 1 [1.62 (0.06)], compared to protocols 2 [2.01 (0.25)] and 3 [2.10 (0.19)] but not between protocols 2 and 3. Circuit and technique choice should be considered in relation to the specific therapeutic aim of treatment.

HIGH FREQUENCY PERCUSSIVE VENTILATION CAN MIMIC AIRWAY PRESSURE RELEASE VENTILATION IN A TEST LUNG MODEL

2004 ◽  
Vol 32 (Supplement) ◽  
pp. A38
Author(s):  
Faera L Byerly ◽  
Bruce A Cairns ◽  
Kathy A Short ◽  
John A Haithcock ◽  
Lynn Shapiro ◽  
...  
Keyword(s):  
High Frequency ◽  
Airway Pressure ◽  
Airway Pressure Release Ventilation ◽  
Lung Model ◽  
Test Lung ◽  
Pressure Release ◽  
Pressure Release Ventilation

Muscarinic agonists and antagonists cause vasodilation in isolated rat lung

1995 ◽  
Vol 78 (4) ◽  
pp. 1404-1411 ◽  
Author(s):  
P. S. Wilson ◽  
P. L. Khimenko ◽  
J. W. Barnard ◽  
T. M. Moore ◽  
A. E. Taylor
Keyword(s):  
Airway Pressure ◽  
Lung Model ◽  
Peak Airway Pressure ◽  
Receptor Subtypes ◽  
Rat Lung ◽  
Muscarinic Agonists ◽  
Selective Antagonist ◽  
M1 Receptors ◽  
Isolated Rat Lung ◽  
Isolated Rat

The present study investigated the ability of atropine and different muscarinic receptor subtypes to affect acetylcholine (ACh)-induced bronchoconstriction and vasodilation in the isolated rat lung model. ACh (10(-7) M) given after U-46619 decreased total (RT), precapillary, and postcapillary vascular resistances and increased peak airway pressure. Atropine (20 microM) decreased RT and precapillary and postcapillary vascular resistances and blocked ACh-induced increases in peak airway pressure. The M1-selective agonist McN-A-343 (1.3 x 10(-5) M) decreased RT from 40.27 +/- 2.98 to 29.20 +/- 2.81 cmH2O.l–1.min-100 g lung wt (P = 0.01), and ACh caused no further dilation. The M1-selective antagonist pirenzepine (1.6 x 10(-6) M) blocked ACh-induced vasodilation. The M2-selective antagonist gallamine (7.5 x 10(-7) M) decreased RT from 45.50 +/- 3.19 to 34.86 +/- 1.25 cmH2O.l–1.min.100 g lung wt (P < 0.05), and after gallamine, ACh further decreased RT to 28.59 +/- 1.75 cmH2O.l–1.min.100 g lung wt (P < 0.01). Neither the selective muscarinic agonists nor antagonists affected peak airway pressures. We conclude that ACh-induced vasodilation in isolated rat lungs preconstricted with U-46619 is mediated by M1 receptors. Atropine-induced vasodilation in this model is mediated through the inhibition of the M2 receptor. We postulate that this represents either a blockade of postganglionic receptors, permitting release of vasodilator substances from local nerve terminals, or a direct vasodilatory effect on the vascular smooth muscle.

scholarly journals Accuracy of P0.1 measurements performed by ICU ventilators: a bench study

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
François Beloncle ◽  
Lise Piquilloud ◽  
Pierre-Yves Olivier ◽  
Alice Vuillermoz ◽  
Elise Yvin ◽  
...  
Keyword(s):  
Airway Pressure ◽  
Inspiratory Effort ◽  
Lung Model ◽  
Respiratory Drive ◽  
Test Lung ◽  
Limits Of Agreement ◽  
Bench Study ◽  
Pressure Time ◽  
Bland Altman Method ◽  
Potential Impact

Abstract Background Occlusion pressure at 100 ms (P0.1), defined as the negative pressure measured 100 ms after the initiation of an inspiratory effort performed against a closed respiratory circuit, has been shown to be well correlated with central respiratory drive and respiratory effort. Automated P0.1 measurement is available on modern ventilators. However, the reliability of this measurement has never been studied. This bench study aimed at assessing the accuracy of P0.1 measurements automatically performed by different ICU ventilators. Methods Five ventilators set in pressure support mode were tested using a two-chamber test lung model simulating spontaneous breathing. P0.1 automatically displayed on the ventilator screen (P0.1vent) was recorded at three levels of simulated inspiratory effort corresponding to P0.1 of 2.5, 5 and 10 cm H2O measured directly at the test lung and considered as the reference values of P0.1 (P0.1ref). The pressure drop after 100 ms was measured offline on the airway pressure–time curves recorded during the automated P0.1 measurements (P0.1aw). P0.1vent was compared to P0.1ref and to P0.1aw. To assess the potential impact of the circuit length, P0.1 were also measured with circuits of different lengths (P0.1circuit). Results Variations of P0.1vent correlated well with variations of P0.1ref. Overall, P0.1vent underestimated P0.1ref except for the Löwenstein® ventilator at P0.1ref 2.5 cm H2O and for the Getinge group® ventilator at P0.1ref 10 cm H2O. The agreement between P0.1vent and P0.1ref assessed with the Bland–Altman method gave a mean bias of − 1.3 cm H2O (limits of agreement: 1 and − 3.7 cm H2O). Analysis of airway pressure–time and flow–time curves showed that all the tested ventilators except the Getinge group® ventilator performed an occlusion of at least 100 ms to measure P0.1. The agreement between P0.1vent and P0.1aw assessed with the Bland–Altman method gave a mean bias of 0.5 cm H2O (limits of agreement: 2.4 and − 1.4 cm H2O). The circuit’s length impacted P0.1 measurements’ values. A longer circuit was associated with lower P0.1circuit values. Conclusion P0.1vent relative changes are well correlated to P0.1ref changes in all the tested ventilators. Accuracy of absolute values of P0.1vent varies according to the ventilator model. Overall, P0.1vent underestimates P0.1ref. The length of the circuit may partially explain P0.1vent underestimation.

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.

Breathing at low lung volumes and chest strapping: a comparison of lung mechanics

1981 ◽  
Vol 50 (3) ◽  
pp. 650-657 ◽  
Author(s):  
N. J. Douglas ◽  
G. B. Drummond ◽  
M. F. Sudlow
Keyword(s):  
Lung Volume ◽  
Maximum Flow ◽  
Normal Subjects ◽  
Lung Mechanics ◽  
Lung Volumes ◽  
Flow Rates ◽  
Recoil Pressure ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

In six normal subjects forced expiratory flow rates increased progressively with increasing degrees of chest strapping. In nine normal subjects forced expiratory flow rates increased with the time spent breathing with expiratory reserve volume 0.5 liters above residual volume, the increase being significant by 30 s (P less than 0.01), and flow rates were still increasing at 2 min, the longest time the subjects could breathe at this lung volume. The increase in flow after low lung volume breathing (LLVB) was similar to that produced by strapping. The effect of LLVB was diminished by the inhalation of the atropinelike drug ipratropium. Quasistatic recoil pressures were higher following strapping and LLVB than on partial or maximal expiration, but the rise in recoil pressure was insufficient to account for all the observed increased in maximum flow. We suggest that the effects of chest strapping are due to LLVB and that both cause bronchodilatation.

Measurement of peak expiratory flow rates in 220 normal children from 4.5 to 18.5 years of age

1963 ◽  
Vol 62 (2) ◽  
pp. 186-189 ◽  
Author(s):  
Andrew B. Murray ◽  
Charles D. Cook ◽  
Joanna H. Shaw ◽  
Mary Alice Shahidi
Keyword(s):  
Peak Expiratory Flow ◽  
Normal Children ◽  
Flow Rates ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

Patterns of gas flow in the upper bronchial tree

1959 ◽  
Vol 14 (5) ◽  
pp. 753-759 ◽  
Author(s):  
J. B. West ◽  
P. Hugh-Jones
Keyword(s):  
Gas Flow ◽  
Lower Lobe ◽  
Bronchial Tree ◽  
High Flow ◽  
Human Beings ◽  
Lobe Bronchus ◽  
Flow Rates ◽  
Expiratory Flow ◽  
Different Gases ◽  
Expiratory Flow Rates

Patterns of gas flow in the upper bronchial tree have been studied by observing the flow of dye and different gases through a lung cast, and by measurements made on open-chested dogs and on human beings at bronchoscopy. Flow is completely laminar throughout the bronchial tree at low expiratory flow rates (up to 10 l/min.) and completely turbulent, proximal to the segmental bronchi, at high flow rates (80 l/min.). Both at low and high expiratory flow rates, gas from segmental bronchi was not uniformly mixed in the lobar or main bronchi which they supplied. The composition of a catheter sample in these airways would therefore not be representative of the alveolar gas in the corresponding lobe or lung unless the alveolar gas in all areas distal to the sampling tube was homogeneous. Penetration of the left upper lobe bronchus by gas from the lower lobe was demonstrated in the model and a normal subject at bronchoscopy. Submitted on September 3, 1958

scholarly journals Manual hyperinflation and the role of physical therapy in intensive care and emergency units

2017 ◽  
Vol 30 (suppl 1) ◽  
pp. 241-248
Author(s):  
Rafael Vinícius Santos Cruz ◽  
Fabiana do Socorro da Silva Dias de Andrade ◽  
Pollyanna Dórea Gonzaga de Menezes ◽  
Bruno Oliveira Gonçalves ◽  
Robson da Silva Almeida ◽  
...  
Keyword(s):  
Intensive Care ◽  
Physical Therapy ◽  
Airway Pressure ◽  
Physical Therapists ◽  
High Peak ◽  
Peak Airway Pressure ◽  
Routine Practice ◽  
Perceived Benefits ◽  
Therapy Technique ◽  
Emergency Units

Abstract Introduction: Although manual hyperinflation (MHI) is a physical therapy technique commonly used in intensive care and emergency units, there is little consensus about its use. Objective: To investigate the knowledge of physical therapists working in intensive care and emergency units about manual hyperinflation. Methods: Data were collected through self-administered questionnaires on manual hyperinflation. Data collection took place between September 2014 and January 2015, in Itabuna and Ilhéus, Bahia, Brazil. Results: The study sample was composed of 32 physical therapists who had between 4 months and 10 years working experience. All respondents affirmed that they used the technique in their professional practice. However, only 34.4% reported it to be a routine practice. 90.6% stated that the most common patient position during manual hyperinflation is “supine”. Participants were almost unanimous (93.8%) in citing secretion removal and cough stimulation as perceived benefits of MHI. High peak airway pressure was identified as being a precaution to treatment with MHI by 84.4% of participants, whilst 100% of the sample agreed that an undrained pneumothorax was a contraindication to MHI. Conclusion: The most common answers to the questionnaire were: supine position during MHI; secretion removal and cough stimulation as perceived benefits; high peak airway pressure as a precaution; and an undrained pneumothorax as a contraindication.

scholarly journals Massive Subcutaneous Emphysema during Laparoscopic Cholecystectomy

1970 ◽  
Vol 21 (1) ◽  
pp. 77-79
Author(s):  
ASM Moosa ◽  
M Baharul Islam ◽  
Shahina Akther ◽  
M Latifur Rahman ◽  
Nazim Uddin Ahmed
Keyword(s):  
Carbon Dioxide ◽  
Laparoscopic Cholecystectomy ◽  
Partial Pressure ◽  
Subcutaneous Emphysema ◽  
Airway Pressure ◽  
Surgical Techniques ◽  
Lung Ventilation ◽  
Peak Airway Pressure ◽  
Sudden Increase ◽  
Partial Pressure Of Oxygen

Laparoscopic surgical techniques are increasingly being applied to treat cholelithiasis and other indications of gallbladder diseases. These procedures however are not without potential morbidity. Herein we describe two patients treated with laparoscopic cholecystectomy; those cases were complicated with subcutaneous emphysema and hypercarbia per-operatively. After discontinuation of pneumoperitoneum, saturation of partial pressure of oxygen (SpO2) gradually increased with improvement of the neck subcutaneous emphysema, at the same time the lung ventilation also improved. Our findings show that we have to stop pneumoperitoneum or decrease partial pressure of end carbon dioxide level immediately, when we find a sudden increase of the peak airway pressure or decrease SpO2 with subcutaneous emphysema during laparoscopic cholecystectomy.   doi: 10.3329/taj.v21i1.3225 TAJ 2008; 21(1): 77-79

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