-
Journal of Anesthesia 2007
Topics: Airway Resistance; Bacteria; Bacterial Infections; Filtration; Humans; Prone Position; Sensitivity and Specificity; Virus Diseases; Viruses
PubMed: 17458667
DOI: 10.1007/s00540-006-0479-5 -
Lancet (London, England) Jul 1988
Topics: Airway Resistance; Animals; Colforsin; Guinea Pigs; Humans; Isoproterenol
PubMed: 2899207
DOI: 10.1016/s0140-6736(88)90707-6 -
Annals of the American Thoracic Society Jun 2013
Topics: Airway Resistance; Humans; Lung; Lung Diseases; Marijuana Smoking
PubMed: 23802822
DOI: 10.1513/AnnalsATS.201302-034ED -
Pediatric Pulmonology Nov 2015The forced oscillation technique (FOT) may be affected by the upper airway artifact in children with airway obstruction. The aim was to test the impact of the artifact...
BACKGROUND
The forced oscillation technique (FOT) may be affected by the upper airway artifact in children with airway obstruction. The aim was to test the impact of the artifact on FOT ability to diagnose asthma in children as recommended by current guidelines.
METHODS
The FOT was performed in 58 asthmatics and 27 controls before and after salbutamol. Respiratory resistance (Rrs) was measured at 8 Hz with a standard generator (SG), and a head generator (HG) that minimizes the upper airway artifact. The response to salbutamol was computed as change in respiratory resistance (Δ%Rrs) and admittance (Δ%Ars) that almost cancels the effect of the upper airway artifact.
RESULTS
Rrs and Δ%Rrs were significantly larger in patients than controls by HG (respectively P < 0.001 and P = 0.002) but not SG, while Δ%Ars was larger in asthma than control by both (P < 0.04). Best discriminators between patients and controls were Rrs or Δ%Rrs by HG and Δ%Ars by SG.
CONCLUSION
In asthmatic children, the upper airway artifact significantly impacts FOT measurements. The diagnostic value may be improved by minimization of the shunt, such as the computation of Δ%Ars.
Topics: Airway Obstruction; Airway Resistance; Albuterol; Asthma; Bronchodilator Agents; Child; Female; Humans; Male; Treatment Outcome
PubMed: 25384559
DOI: 10.1002/ppul.23131 -
Journal of Applied Physiology... Oct 1987Nasal airway resistance was assessed in halothane-anesthetized rats by measuring the transnasal pressure at constant airflow through both nasal cavities. Low inflation...
Nasal airway resistance was assessed in halothane-anesthetized rats by measuring the transnasal pressure at constant airflow through both nasal cavities. Low inflation pressures (2.5-5 cmH2O) decreased nasal airway resistance, whereas higher inflation pressures (10-20 cmH2O) caused a biphasic response: an initial increase in resistance followed by a decrease in resistance. The nasal responses to all levels of inflation were completely abolished by hexamethonium, guanethidine, or bretylium pretreatment or cervical sympathectomy and greatly lessened by cervical vagotomy or phenoxybenzamine pretreatment. Atropine and propranolol pretreatments had no effect on the responses. These findings indicate that the nasal airway resistance is related to the level of inflation through pulmonary reflexes with afferents along the vagi and efferents via the alpha-adrenergic nervous system.
Topics: Airway Resistance; Anesthesia; Animals; Blood Pressure; Female; Lung; Male; Nose; Rats; Rats, Inbred Strains; Sympathectomy; Vagotomy
PubMed: 3693166
DOI: 10.1152/jappl.1987.63.4.1339 -
The Journal of Physiology Dec 19891. In pentobarbitone-anaesthetized dogs with constant-flow vascular perfusion of nasal mucosa on both sides, nasal airway resistance, vascular resistance, vascular...
1. In pentobarbitone-anaesthetized dogs with constant-flow vascular perfusion of nasal mucosa on both sides, nasal airway resistance, vascular resistance, vascular capacitance (via changes in total venous outflow) and blood flow in the anterior and posterior venous systems were measured. 2. Electrical stimulation of the cut peripheral ends of the cervical sympathetic trunk, caudal nasal nerve, or major palatine nerve increased vascular resistance and decreased vascular capacitance and airway resistance. Propranolol and atropine had no effect on the responses while bretylium completely abolished them; phentolamine greatly lessened the vascular resistance response and partially decreased the vascular capacitance and airway responses. Hence, sympathetic stimulation causes constriction of the resistance vessels via alpha-adrenergic mechanism and constriction of capacitance vessels via alpha-adrenergic as well as some non-adrenergic and non-cholinergic mechanisms. 3. Denervation of the cervical sympathetic trunk, caudal nasal nerve and major palatine nerve decreased nasal vascular resistance and increased vascular capacitance and airway resistance, suggesting tonic sympathetic discharge to nasal mucosa via caudal nasal and major palatine nerves. 4. Electrical stimulation of the nerve of pterygoid canal decreased vascular resistance but increased vascular capacitance (in the posterior venous system) and airway resistance to low-voltage stimulation (below 10 V), and decreased vascular capacitance (in the anterior venous system) and airway resistance to high-voltage stimulation (above 10 V). Hexamethonium reversed the vascular resistance response as well as vascular capacitance and airway responses to high-voltage stimulation. Bretylium and phentolamine enhanced the vascular resistance response and reversed vascular capacitance and airway resistance responses to high-voltage stimulation. Hence, low-voltage stimulation results in parasympathetic dilatation of resistance and capacitance vessels whereas high-voltage stimulation results in parasympathetic dilatation of resistance vessels and sympathetic constriction of capacitance vessels. The parasympathetic vasodilatation was atropine resistance and the sympathetic vasoconstriction was partially via alpha-adrenergic mechanisms. 5. Denervation of the nerve of pterygoid canal did not affect vascular resistance, vascular capacitance or airway resistance suggesting negligible tonic parasympathetic and sympathetic discharges to nasal blood vessels via the nerve. 6. Simultaneous optimal stimulation of sympathetic and parasympathetic nerves resulted in vasoconstriction, especially in capacitance vessels, suggesting sympathetic predominance over parasympathetic control.
Topics: Airway Resistance; Animals; Autonomic Nervous System; Dogs; Female; Male; Nasal Mucosa; Vascular Resistance
PubMed: 2621625
DOI: 10.1113/jphysiol.1989.sp017864 -
Respiratory Physiology & Neurobiology Jun 2015We have recently shown that if the lung parenchyma is modeled in 2 dimensions as a network of springs arranged in a pattern of repeating hexagonal cells, the...
We have recently shown that if the lung parenchyma is modeled in 2 dimensions as a network of springs arranged in a pattern of repeating hexagonal cells, the distortional forces around a contracting airway propagate much further from the airway wall than classic continuum theory predicts. In the present study we tested the hypothesis that this occurs because of the negligible shear modulus of a hexagonal spring network. We simulated the narrowing of an airway embedded in a hexagonal network of elastic alveolar walls when the hexagonal cells of the network offered some resistance to a change in shape. We found that as the forces resisting shape change approach about 10% of the forces resisting length change of an individual spring the range of distortional force propagation in the spring network fell of rapidly as in an elastic continuum. We repeated these investigations in a 3-dimensional spring network composed of space-filling polyhedral cells and found similar results. This suggests that force propagation away from a point of local parenchymal distortion also falls off rapidly in real lung tissue.
Topics: Airway Resistance; Computer Simulation; Elasticity; Humans; Linear Models; Models, Cardiovascular; Nonlinear Dynamics; Pulmonary Alveoli
PubMed: 25812796
DOI: 10.1016/j.resp.2015.03.004 -
British Journal of Anaesthesia Jul 1990
Review
Topics: Airway Resistance; Anesthesia, General; Humans; Lung Compliance; Mathematics; Respiratory Mechanics
PubMed: 2200483
DOI: 10.1093/bja/65.1.4-a -
Journal of Applied Physiology... Dec 1996It has been demonstrated that methacholine (MCh) challenge produces a greater increase in lung resistance in immature than in mature rabbits (R. S. Tepper, X. Shen, E....
It has been demonstrated that methacholine (MCh) challenge produces a greater increase in lung resistance in immature than in mature rabbits (R. S. Tepper, X. Shen, E. Bakan, and S. J. Gunst. J. Appl. Physiol. 79: 1190-1198, 1995). To determine whether this maturational difference in the response to MCh was primarily related to changes in airway resistance (Raw) or changes in tissue resistance, we assessed airway narrowing in 1-, 2-, and 6-mo-old rabbits during intravenous MCh challenge (0.01-5.0 mg/kg). Airway narrowing was determined from measurements of Raw in vivo and from morphometric measurements on lung sections obtained after rapidly freezing the lung after the MCh challenge. The fold increase in Raw was significantly greater for 1- and 2-mo-old animals than for 6-mo-old animals. Similarly, the degree of airway narrowing assessed morphometrically was significantly greater for 1- and 2-mo-old animals than for 6-mo-old animals. The fold increase in Raw was highly correlated with the degree of airway narrowing assessed morphometrically (r2 = 0.82, P < 0.001). We conclude that the maturational difference in the effect of MCh on lung resistance is primarily caused by greater airway narrowing in the immature rabbits.
Topics: Airway Resistance; Animals; Animals, Newborn; Dose-Response Relationship, Drug; Methacholine Chloride; Rabbits; Respiratory System
PubMed: 9018516
DOI: 10.1152/jappl.1996.81.6.2637 -
Journal of Pharmacological and... Nov 1993The pathophysiology of human airway narrowing is only partly understood. In order to gain more insight in the mechanisms of human lung diseases and potential beneficial... (Review)
Review
The pathophysiology of human airway narrowing is only partly understood. In order to gain more insight in the mechanisms of human lung diseases and potential beneficial therapeutic agents, adequate models are needed. Animal airway models are of limited value since lung diseases such as asthma and chronic obstructive pulmonary disease (COPD) are unique to humans and because the mechanisms of airway narrowing differ between species. Therefore, it is important to perform studies on human isolated airways. We describe the models that have been developed to study airway function in vitro, emphasizing human airway preparations. The easily prepared airway strip and ring preparations are described first. The potential damage during preparation and the interference with airway structure are important drawbacks in these preparations. Lung parenchymal strips, described next, were designed in order to study responsiveness of small airways. However, parenchymal strips are anatomically complex, and responsiveness is determined by the relative amounts of airway and vascular smooth muscle. The lack of reproducibility between species and even within one animal limits their usefulness. Airway tube preparations, in which luminal and serosal stimulation can be separated, enable us to study the modulatory role of the airways epithelium in vitro. Furthermore, airway compliance can be measured. In the isolated perfused lung preparation, relationships between the airways and the vascular system are preserved and the interaction between these two systems can be studied. Weight gain due to fluid extravasation is a problem in this model which has not been used yet to study human lungs in vitro. Next, methodological aspects such as tissue handling and storage, recording of responses, removal of the epithelium, and electrical field stimulation are discussed in some detail. Although animal airways tissue can be studied immediately after removal, human tissue is often obtained with some delay. However, this seems tenable since electron microscopy of lung tissue obtained at autopsy showed that recovery of the preparation occurs during incubation of carbogenated Krebs-Henseleit (K-H) buffer. Dissected airways can be stored overnight in cooled K-H buffer until up to 55 hr after resection without losing viability. Commonly used physiological salt solutions which bath the tissue contain osmotic molecules, ions important for contractility, glucose as a substrate, and a bicarbonate-carbon dioxide buffer.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Airway Resistance; Humans; In Vitro Techniques; Models, Biological; Pulmonary Medicine; Respiratory Physiological Phenomena
PubMed: 8305711
DOI: 10.1016/1056-8719(93)90034-c