Methods of Airway Resistance Assessment
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Maximum Expiratory Flow Rates in Induced Bronchoconstriction in Man
Maximum expiratory flow rates in induced bronchoconstriction in man A. Bouhuys, … , B. M. Kim, A. Zapletal J Clin Invest. 1969;48(6):1159-1168. https://doi.org/10.1172/JCI106073. Research Article We evaluated changes of maximum expiratory flow-volume (MEFV) curves and of partial expiratory flow-volume (PEFV) curves caused by bronchoconstrictor drugs and dust, and compared these to the reverse changes induced by a bronchodilator drug in previously bronchoconstricted subjects. Measurements of maximum flow at constant lung inflation (i.e. liters thoracic gas volume) showed larger changes, both after constriction and after dilation, than measurements of peak expiratory flow rate, 1 sec forced expiratory volume and the slope of the effort-independent portion of MEFV curves. Changes of flow rates on PEFV curves (made after inspiration to mid-vital capacity) were usually larger than those of flow rates on MEFV curves (made after inspiration to total lung capacity). The decreased maximum flow rates after constrictor agents are not caused by changes in lung static recoil force and are attributed to narrowing of small airways, i.e., airways which are uncompressed during forced expirations. Changes of maximum expiratory flow rates at constant lung inflation (e.g. 60% of the control total lung capacity) provide an objective and sensitive measurement of changes in airway caliber which remains valid if total lung capacity is altered during treatment. Find the latest version: https://jci.me/106073/pdf Maximum Expiratory Flow Rates in Induced Bronchoconstriction in Man A. Bouiuys, V. R. HuNTr, B. M. Kim, and A. ZAPLETAL From the John B. Pierce Foundation Laboratory and the Yale University School of Medicine, New Haven, Connecticut 06510 A B S T R A C T We evaluated changes of maximum ex- rates are best studied as a function of lung volume. -
Introduction to Airway Resistance Measurements
Introduction to airway resistance measurements Dr. David Kaminsky Department of Medicine The University of Vermont VT 05405 Burlington UNITED STATES OF AMERICA [email protected] AIMS Review physiology of airway resistance Survey measures of airway resistance Provide examples of clinical applications Highlight research applications SUMMARY Airway resistance (Raw) is one of the fundamental features of the mechanics of the respiratory system. While the flow-volume loop offers insight into the volume and flow of air, it is limited in terms of specific information regarding lung mechanics. Airway resistance is the ratio of driving pressure divided by flow through the airways. It specifies the pressure required to achieve a flow of air with a velocity of 1L/sec. If the airway is represented by a simple, rigid tube, with laminar flow of air through it, the airway resistance Raw = (8 x L x )/ r4, where L = length of the tube, = viscosity of the gas, and r = radius of the tube. It is important to note that the r4 relationship demonstrates how sensitive resistance is to the size of the tube, varying inversely with the 4th power of the radius. The inner diameter of the airway is itself determined by many factors, including airway smooth muscle contractile state, airway wall thickness (related to inflammation, edema and remodeling), airway wall buckling and formation of mucosal folds, the interdependence, or linkage, of airway and surrounding lung parenchyma, and the intrinsic elastic recoil of the lung parenchyma, which serves as a load on the airway and variably resists bronchoconstriction. Of course, the airways are not rigid tubes, and in fact flow is a complex process involving both laminar and turbulent conditions, so this calculation of Raw is an approximation only. -
Does the Reduction of Inferior Turbinate Affect Lower Airway Functions?
Braz J Otorhinolaryngol. 2019;85(1):43---49 Brazilian Journal of OTORHINOLARYNGOLOGY www.bjorl.org ORIGINAL ARTICLE Does the reduction of inferior turbinate affect lower ଝ airway functions? a,∗ a b a Ozlem Unsal , Mehtap Ozkahraman , Mufide Arzu Ozkarafakili , Meltem Akpinar , a a a Arzu Yasemin Korkut , Senem Kurt Dizdar , Berna Uslu Coskun a Sisli Hamidiye Etfal Training and Research Hospital, Clinic of Otorhinolaryngology, Istanbul, Turkey b Sisli Hamidiye Etfal Training and Research Hospital, Clinic of Pulmonary Diseases, Istanbul, Turkey Received 31 July 2017; accepted 16 October 2017 Available online 6 November 2017 KEYWORDS Abstract Acoustic rhinometry; Introduction: Although the nose and lungs are separate organs, numerous studies have reported Turbinates; that the entire respiratory system can be considered as a single anatomical and functional unit. Hypertrophy; The upper and lower airways affect each other either directly or through reflex mechanisms. Spirometry; Objective: In this study, we aimed to evaluate the effects of the radiofrequency ablation of Respiratory system persistent inferior turbinate hypertrophy on nasal and pulmonary function. Methods: Twenty-seven patients with bilateral persistent inferior turbinate hypertrophy with- out septal deviation were included in this study. All of the patients were evaluated using anterior rhinoscopy, nasal endoscopy, acoustic rhinometry, a visual analogue scale, and flow-sensitive spirometry on the day before and 4 months after the radiofrequency ablation procedure. Results: The post-ablation measurements revealed that the inferior turbinate ablation caused an increase in the mean cross-sectional area and volume of the nose, as well as in the forced expiratory volume in 1 s, forced vital capacity, and peak expiratory flow of the patients. -
Role of the Allergist-Immunologist and Upper Airway Allergy in Sleep-Disordered Breathing
AAAAI Work Group Report Role of the Allergist-Immunologist and Upper Airway Allergy in Sleep-Disordered Breathing Dennis Shusterman, MD, MPHa, Fuad M. Baroody, MDb, Timothy Craig, DOc, Samuel Friedlander, MDd, Talal Nsouli, MDe, and Bernard Silverman, MD, MPHf; on behalf of the American Academy of Allergy, Asthma & Immunology’s Rhinitis, Rhinosinusitis and Ocular Allergy Committee Work Group on Rhinitis and Sleep-disordered Breathing San Francisco, Calif; Chicago, Ill; Hershey, Pa; Solon, Ohio; Washington, DC; and Brooklyn, NY BACKGROUND: Sleep-disordered breathing in general and RESULTS: Survey results were returned by 339 of 4881 active obstructive sleep apnea in particular are commonly encountered members (7%). More than two-third of respondents routinely conditions in allergy practice. Physiologically, nasal (or asked about sleep problems, believed that sleep-disordered nasopharyngeal) obstruction from rhinitis, nasal polyposis, or breathing was a problem for at least a “substantial minority” adenotonsillar hypertrophy are credible contributors to snoring (10%-30%) of their adult patients, and believed that medical and nocturnal respiratory obstructive events. Nevertheless, therapy for upper airway inflammatory conditions could existing practice parameters largely relegate the role of the potentially help ameliorate sleep-related complaints. Literature allergist to adjunctive treatment in cases of continuous positive review supported the connection between high-grade nasal airway pressure intolerance. congestion/adenotonsillar hypertrophy and obstructive sleep OBJECTIVES: To survey active American Academy of Allergy, apnea, and at least in the case of pediatric patients, supported the Asthma & Immunology members regarding their perceptions use of anti-inflammatory medication in the initial management and practices concerning sleep-disordered breathing in adult and of obstructive sleep apnea of mild-to-moderate severity. -
Heated and Humidified High-Flow Oxygen Therapy Reduces Discomfort During Hypoxemic Respiratory Failure
Heated and Humidified High-Flow Oxygen Therapy Reduces Discomfort During Hypoxemic Respiratory Failure Elise Cuquemelle MD, Tai Pham MD, Jean-Franc¸ois Papon MD PhD, Bruno Louis PhD, Pierre-Eric Danin MD, and Laurent Brochard MD PhD BACKGROUND: Non-intubated critically ill patients are often treated by high-flow oxygen for acute respiratory failure. There is no current recommendation for humidification of oxygen devices. METHODS: We conducted a prospective randomized trial with a final crossover period to compare nasal airway caliber and respiratory comfort in patients with acute hypoxemic respiratory failure receiving either standard oxygen therapy with no humidification or heated and humidified high- flow oxygen therapy (HHFO2) in a medical ICU. Nasal airway caliber was measured using acoustic rhinometry at baseline, after 4 and 24 hours (H4 and H24), and 4 hours after crossover (H28). Dryness of the nose, mouth, and throat was auto-evaluated and assessed blindly by an otorhinolaryngologist. After the crossover, the subjects were asked which system they preferred. RESULTS: Thirty subjects completed the protocol and were analyzed. Baseline median oxygen flow was 9 and 12 L/min in the ؍ standard and HHFO2 groups, respectively (P .21). Acoustic rhinometry measurements showed no difference between the 2 systems. The dryness score was significantly lower in the HHFO2 group at H4 During the crossover period, dryness increased promptly .(004. ؍ and H24 (0 vs 8, P (007. ؍ vs 6, P 2) ؍ after switching to standard oxygen and decreased after switching to HHFO2 (P .008). Sixteen subjects ؍ (53%) preferred HHFO2 (P .01), especially those who required the highest flow of oxygen at admis- ؍ sion (P .05). -
Dynamic Mechanics of the Lung Answer to the Last Class’S Question
Dynamic mechanics of the lung Answer to the Last class’s question Resistive (Frictional Forces) Opposing Lung Inflation Frictional opposition occurs only when the system is in motion. Frictional opposition to ventilation has the two components: 1. tissue viscous resistance 2. airway resistance. Tissue Viscous Resistance: the impedance of motion (opposition to flow) caused by displacement of tissues during ventilation that includes the lungs, rib cage, diaphragm, and abdominal organs. The frictional resistance is generated by the movement of each organ surface sliding against the other (e.g., the lung lobes sliding against each other and against the chest wall). Tissue resistance accounts for only approximately 20% of the total resistance to lung inflation. In conditions : obesity, pleural fibrosis, and ascites, the tissue viscous resistance increases the total impedance to ventilation. Airway Resistance (flow resistance) - Resistance to ventilation by the movement of gas through the airways. • accounts for approximately 80% of the frictional resistance to ventilation. • -is usually expressed in units of cm H2O/L/sec: R= ∆P/ ∆V • Airway resistance in healthy adults ranges from approximately 0.5 to 2.5 cm H2O/L/sec. • To cause gas to flow into or out of the lungs at 1 L/sec, a healthy person needs to lower his alveolar pressure 0.5 to 2.5 cm H2O below atmospheric pressure. Measurement of Airway Resistance • Airway resistance is the pressure difference between the alveoli and the mouth divided by a flow rate. Mouth pressure is easily measured with a manometer. Alveolar pressure can be deduced from measurements made in a body plethysmograph. -
Subjective and Objective Improvement in Breathing After Rhinoplasty
ORIGINAL ARTICLE ONLINE FIRST Subjective and Objective Improvement in Breathing After Rhinoplasty Richard A. Zoumalan, MD; Minas Constantinides, MD Objective: To determine whether rhinoplasty im- cedures undergone, including spreader grafts and alar bat- proves subjective and objective nasal patency. ten grafts, and on the absence of osteotomies. These groups had similar results. In patients with severe obstruction, Design: Retrospective study including subjective breath- all measured values improved more than any other sub- ing scores and acoustic rhinometry before and 6 to 9 group, including the MCA, which improved signifi- months after septorhinoplasty among a cohort of 31 pa- cantly by an average of 55%. Patients with normal pre- tients. We used a paired t test to analyze the difference operative MCA values did not experience any significant between preoperative and postoperative values. changes except for an anterior shift in MCA. Setting: Academic medical center. Conclusions: Septorhinoplasty increases nasal vol- ume, decreases nasal resistance, and advances the MCA Patients: Patients undergoing septorhinoplasty with po- anteriorly. These changes coexist with subjective im- tassium titanyl phosphate laser turbinate reduction at a single institution. provements in nasal patency, which suggests that this new anatomic configuration creates a positive outcome on na- Results: The mean subjective breathing scores im- sal airflow. Spreader grafts do not increase the MCA sig- proved significantly, with an overall improvement of 38%. nificantly. Patients with preoperative severe obstruc- The overall mean volume increased and the overall re- tion have the best overall improvement, whether measured sistance decreased, but the changes were significant only subjectively or objectively. on the right side. -
The Respiratory System - 3 Pressure Changes and Resistance
The Respiratory System - 3 Pressure changes and resistance Jennifer Carbrey Ph.D. Department of Cell Biology image by OCAL, http://www.clker.com/clipart-26501.html, public domain Respiratory System 1. Anatomy and mechanics 2. Lung volumes and compliance 3. Pressure changes and resistance 4. Pulmonary function tests and alveolar ventilation 5. Oxygen transport 6. CO2 transport and V/Q mismatch 7. Regulation of breathing 8. Exercise and hypoxia Respiratory System pleural sac: inner layer covers lungs outer layer is attached to chest wall fluid in between image by OCAL (modified), http://www.clker.com/clipart-12109.html, public domain Pressure & Lung Volumes PA Lungs P Intrapleural fluid ip Chest wall Patm = 0 mm Hg = 760 mm Hg Pressure & Lung Volumes PA Pip = -3 PA – Pip determines lung size and PA - Patm determines air flow Pressure & Lung Volumes end of expiration during expiration PA= +1 PA=0 Pip = -4 Pip = -3 during inspiration end of inspiration PA – Pip determines lung size and PA=0 PA= -1 PA - Patm determines air flow F = (PA- Patm) /R Pip = -5 Pip = -6 P1V1=P2V2 – Boyles Law Resistance & Air Flow F = (PA- Patm) /R Factors that influence resistance: 1. Airway diameter – the smaller the diameter the more resistance in that tube in lung, more tubes as you go further into lung - so combined resistance gets lower as enter lung 2. Lung volume – if have a greater lung volume then airways are not as compressed – can be a compensation to lung disease with increased resistance 3. Muscle tone – parasympathetic stimulation causes bronchiolar smooth muscle to contract; sympathetic stimulation causes relaxation 4. -
Alteraes Na Mucosa Nasal Provocadas Pela Presso Atmosfrica, Oxignio E
ALTERAÇÕES NA MUCOSA NASAL PROVOCADAS PELA PRESSÃO ATMOSFÉRICA, OXIGÉNIO E OUTROS FACTORES PAULO SÉRGIO ALVES VERA-CRUZ PINTO Dissertação de doutoramento em Ciências Médicas 2009 PAULO SÉRGIO ALVES VERA-CRUZ PINTO ALTERAÇÕES NA MUCOSA NASAL PROVOCADAS PELA PRESSÃO ATMOSFÉRICA, OXIGÉNIO E OUTROS FACTORES Dissertação de candidatura ao grau de Doutor em Ciências Médicas, submetida ao Instituto de Ciências Biomédicas de Abel Salazar da Universidade do Porto. Orientador – Professor Doutor Carlos Zagalo, professor do Instituto de Ciências da Saúde Egas Moniz. Co-Orientador – Professor Doutor Artur Águas, professor catedrático do Instituto de Ciências Biomédicas de Abel Salazar da Universidade do Porto. Porto 2009 2 À Carla, ao Gonçalo e ao Bernardo 3 4 “Try and leave this world a little better than you found it and when your turn come to die, you can die happy in feeling that at any rate you have not wasted your time but have done your best.” Lord Robert Baden-Powell's Last Message to Scouts, 1941 5 6 ÍNDICE Preceitos legais ...................................................................................................................9 Agradecimentos.................................................................................................................10 INTRODUÇÃO...................................................................................................................12 1- Anatomia das Fossas Nasais no Humano ................................................................12 2 - Anatomia das Fossas Nasais no Rato .....................................................................14 -
Airway Resistance Measurements in the Evaluation of Obstructive Lung Disease by Michael Snow, RPFT
Clinical Perspectives Airway Resistance Measurements in the Evaluation of Obstructive Lung Disease by Michael Snow, RPFT hronic obstructive Measuring maximal airflow is determined by the size pulmonary disease (COPD) and airflow of the airway. Once maximal air- Casthma are growing health prob- Most commonly, the diagnosis flow has been achieved, continu- lems and are expected to be of airway obstruction is based on ing to increase driving pressure among the leading causes of changes in airflow as assessed by will not increase airflow. In a mortality worldwide as we enter maximal, forced expiratory patient model, the expiratory the next century. Recent studies maneuvers (FEV1 and PEF). airflow proceeds from small, evaluating the role of quality of Although these maneuvers non-rigid, peripheral airways, life indicators with educational reflect changes in airway resis- combining into larger, more interventions in asthma, as well tance, forced expiratory maneu- rigid, central airways. The cumu- as a growing understanding of vers reflect a complex, dynamic lative cross-sectional area of the the role of inflammatory relationship between patient larger airways determines the processes in the progression of effort, muscle strength, compli- maximal airflow. COPD, have highlighted the ance, and elastic recoil, as well as The magnitude of the inspired importance of early diagnosis airway resistance. As a result, volume is determined by the and treatment of airway using forced expiratory maneu- elastic properties of the lung obstruction.1-4 The primary vers to assess changes in airway combined with muscle strength cause of airway obstruction, resistance can frequently be mis- required to overcome these regardless of etiology, is leading or create uncertainty forces. -
Physiologic Changes in the Elderly Michael C
Theme 1: Physiologic Changes in the Elderly Michael C. Lewis, MD Associate Professor of Clinical Anesthesiology This unit forms the second part of a series of teaching modules on Anesthesia for the Elderly. It will guide you step-by-step through some salient physiologic differences between the aged and the younger adult population. It is our hope that on completing this component you will appreciate why understanding physiologic differences between these age groups guides us in our anesthetic management. Introduction This section describes significant physiologic changes between the aged and younger populations as defined in longitudinal studies of healthy people. It will be seen that aging results in significant anatomic and functional changes in all the major organ systems. Aging is marked by a decreased ability to maintain homeostasis. However, within the elderly population there is significant heterogeneity of this decline. This unit introduces facts in a systemic fashion, and then asks you some questions testing your mastery of the information. Each section is self-contained and leads to the next. One should not progress until one has fully understood the material in the previous section. Goals After completing this unit the resident should be able to: Understand the main structural and functional changes associated with normal aging Understand how these changes will impact the practice of anesthesiology 1 Cardiovascular System (CVS) “In no uncertain terms, you are as old as your arteries.” — M. F. Roizen, RealAge It is controversial whether significant CVS changes occur with aging. Some authors claim there is no age-related decline in cardiovascular function at rest. -
Reference Values of Total Respiratory Resistance, Determined with the "Opening" Interruption Technique
Eur Respir J 1989. 2. 966-971 Reference values of total respiratory resistance, determined with the "opening" interruption technique P.H. Vooren*, B.C. van Zomeren ** Reference values of total respiratory resistance, determined with the "open *Department of Pulmonary Diseases, University ing" interruption technique. P.H. Vooren, B.C. van Zorneren. Hospital, Leiden, Holland. ABSTRACT: In a large epidemiological survey of lung function the sub· jects performed maximum expiratory now volume (MEFV) manoeuvres. They were also Interviewed by trained interviewers using a standardized ••Department of Mathematics, Delft Universiry of questionnaire. In a random subset of the subjects the resistance of the Technology, Holland. respiratory system was measured with the "opening" Interruption tech· nlque, In which the mouth pressure before the end of the Interruption period Is divided by the flow shortly after the end of lt. The subset con· Correspondence: Dr. P.H. Vooren, Pulmonary Depart· talned men and women, and smokers as well as nonsmokers, 229 of whom ment, Building 1, C3P, Academic Hospital, 2333 AA were considered to be healthy because they bad no history of compllants Leiden, Netherlands. and a "normal" now-volume curve. ln this group mean Inspiratory and expiratory reslstances did not differ signlncantly (0.27 and 0.29 for men and 0.39 and 0.38 kPa·t1·s for women). The averages of In· and expiratory Keywords: Asynchronous ventilation; reference resistance were 0.28±0.10 kPa·t1·s for men and 0.39±0.11 kPa·t1·s for values; respiratory resistance; small airways. women. The resistance values were slightly but significantly correlated with body height, FEV and MEF501 but not with smoking habits.