Obstruction Of Airflow Research Articles

PI3K signalling in chronic obstructive pulmonary disease and opportunities for therapy.

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease characterised by airway inflammation and progressive obstruction of the lung airflow. Current pharmacological treatments include bronchodilators, alone or in combination with steroids, or other anti-inflammatory agents, which have only partially contributed to the inhibition of disease progression and mortality. Therefore, further research unravelling the underlying mechanisms is necessary to develop new anti-COPD drugs with both lower toxicity and higher efficacy. Extrinsic signalling pathways play crucial roles in COPD development and exacerbations. In particular, phosphoinositide 3-kinase (PI3K) signalling has recently been shown to be a major driver of the COPD phenotype. Therefore, several small-molecule inhibitors have been identified to block the hyperactivation of this signalling pathway in COPD patients, many of them showing promising outcomes in both preclinical animal models of COPD and human clinical trials. In this review, we discuss the critically important roles played by hyperactivated PI3K signalling in the pathogenesis of COPD. We also critically review current therapeutics based on PI3K inhibition, and provide suggestions focusing on PI3K signalling for the further improvement of the COPD phenotype. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

EFFECT OF HAREETAKYADI YOGA IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE – PRE TEST-POST TEST DESIGN

Chronic Obstructive Pulmonary Disease (COPD) is a lung disease characterized by chronic obstruction of lung airflow that interferes with normal breathing, which is progressive and is not fully reversible. COPD includes chronic bronchitis and emphysema. Symptoms of COPD are well explained in Ayurveda in the context of Kasa and Swasa among which chronic bronchitis can be better correlated to Vataja and Kaphaja kasa and emphysema to Tamaka swasa. COPD is characterized by mucous hyper secretion, airway narrowing, fibrosis and destruction of lung parenchyma. Even though the existing conventional management is excellent, Ayurveda provides additional benefits such as improvement in quality of life. The study drug Hareetakyadi yoga is mentioned in Prakarana of kasa in Chikitsa manjari. The objective of the study was to evaluate the Effect of Hareetakyadi yoga in Chronic Obstructive Pulmonary Disease. The Study includes 10 subjects of age group 40-70 years of both gender, diagnosed clinically and as per investigations satisfying COPD, stage 1 & 2 as per GOLD criteria of spirometry attending department of Kayachikitsa, Government Ayurveda College, Thiruvananthapuram. A protocol from Deepana to Virechana were done as preparatory phase before administering drug. Hareetakyadi yoga having the properties of Kapha vata hara, Agni deepana and Rasayana property seems to be effective in the management of this disease.

Clinical Pharmacist Approach towards Effectiveness of Pulmonary Rehabilitation of the Patient with COPD: A Randomized Controlled Study

Abstract: Background: COPD is characterized by chronic obstruction of lung airflow that interferes with normal breathing and is not fully reversible. Pulmonary rehabilitation is widely accepted as a best result outcome treatment for COPD patients. Clinical pharmacist play a very important role in patient prescription analysis, promoting the Quality of life, patient education, in developing the drug regimen, sensitivity and allergic condition of the patient to the drugs, finding out any ADRs. Objectives: To compare and assess the impact of pharmacist approach on Health related quality of Life of COPD patients undergoing pulmonary rehabilitation at two different time point. Results: Total 112 patients were screened as per study criteria, 70 were recruited and randomized into control and intervention groups of 35 each, respectively. Compared to baseline QOL score, it was improved at the follow-up in intervention group. Out of 35 subjects 33 subjects has shown good and very good QOL (94.28%). All the domains of QOL were improved compared to control group at the follow-up. Highest improved domain was physical health domain among all (difference 25.83) and lowest was socio-economic domain (difference 12.14) Mean total score of quality of life at follow-up has the significant difference 18.1 (p<0.0001). Conclusion: This study elaborated that quality of life of patients with COPD undergoing pulmonary rehabilitation was improved after the clinical pharmacists approach when compared to only standard treatment (control group). Key words: COPD, Pulmonary rehabilitation, Collaborative approach, Pharmacist’s intervention, Pharmaceutical care, Quality of life.

Gut microbiota modulates COPD pathogenesis: role of anti-inflammatory Parabacteroides goldsteinii lipopolysaccharide

ObjectiveChronic obstructive pulmonary disease (COPD) is a global disease characterised by chronic obstruction of lung airflow interfering with normal breathing. Although the microbiota of respiratory tract is established to be...

Role of Depression in Chronic Obstructive Pulmonary Disease Patients

Abstract Chronic obstructive pulmonary disease is a progressive lung disease characterized by chronic obstruction of the lung airflow that interferes with normal bleeding and is not fully reversible. Chronic smoking is the most common risk factor for COPD causing severe cough, wheezing, labored breathing and reduced functionality. COPD not only exerts pulmonary symptoms but also has a spill over the extra pulmonary effects. Owing to the impact of the disease, it may lead to conditions like osteoporosis, cardiovascular complications as well as to psychological effects such as depression and anxiety. Such comorbidities are hidden and are not effectively treated. Depression, one of the most common hidden comorbidities is known to be present but never diagnosed. Various scales like HAM-D and Bode Index can be used to diagnose the extent of depression. Our review mainly focuses on the various studies conducted worldwide and comparing the results of the same. Based on the worldwide analysis, depression is known to affect a COPD patient at later stages and requires immediate diagnosis and appropriate treatment.

Bacteriological profile and antibiotic sensitivity pattern in chronic obstructive pulmonary disease patients

Chronic obstructive pulmonary disease (COPD) is a progressive chronic disease, which is characterized by obstinate obstruction of airflow with an enhanced chronic inflammatory response in the airways and the lung to toxic elements or gases. COPD is a major etiology of morbidity and one among the primary causes of the death globally. The objective of this study is to analyze the bacteriological profile of the patients with COPD and also to study their antimicrobial sensitivity pattern, which may help to scheme a proper antibiotic treatment to the COPD patients, which will have a beneficial effect in preventing the morbidity and mortality of the disease. A narrative review of the literature was carried out after a bibliographical search on the database PubMed, Science Direct and Scopus and active search lists of bibliographical references of articles selected up to November 2019. According to various studies addressed, the causative agents in COPD from both sputum and bronchoscopic samples are found to be Haemophilus influenza, Streptococcus pneumoniae, and Moraxella catarrhalis. However, to conclude, the bacterial flora in COPD varies with disease severity as Gram-negative organisms, such as Pseudomonas aeruginosa are more commonly detected in patients with more severe airflow obstruction in both stable COPD and in exacerbations.

Lung volume reduction surgery: from National Emphysema Treatment Trial to non-intubated awake video-assisted thoracoscopic surgery.

Chronic obstructive pulmonary disease (COPD) is a major public health problem. Loss of elastic recoil, hyperinflation and obstruction of the expiratory airflow lead to an increased breathing work, which results in dyspnea during minimal physical activity of the patients. Reduction of the lung volume in these patients leads to improvement of dyspnea, physical activity and quality of life in these patients. Beside endoscopic lung volume reduction (ELVR), lung volume reduction surgery (LVRS) represents an important and valuable treatment option for patients with advanced lung emphysema. Since the National Emphysema Treatment Trial (NETT), thoracic surgery experienced a remarkable evolution of the surgical techniques enabling safe surgery and quick recovery in this critically ill patient cohort. A paradigm shift from open surgical approaches to most minimally invasive techniques accompanied by improvement of anesthesiologic management of these patients was evident. Moreover, indications for LVRS, which were originally described in the NETT, were extended to apply for further groups of patients with advanced lung emphysema, enabling significant clinical improvement in well-selected patients with a low perioperative morbidity and mortality. The current review will give an overview of the historical approaches for LVRS, highlight the indications for LVRS and discuss the development of the surgical approaches.

A 10 Year Post Mortem Study of Choking Cases Brought to the Mortuary of a Tertiary Care Hospital in Imphal

Choking is the obstruction of air flow into the lungs and is almost always accidental. In this paper, cases ofchoking mistaken to be deaths due to foul play are studied. Any complaint is not true unless it is proved so.In all these cases, family members blamed the deaths on some parties who were in fact completely innocent.Meticulous autopsy helped in establishing the exact cause of death in these cases by disproving the falsecharge of assault. From the legal standpoint, the importance of establishing an exact diagnosis is obvious.

Fixed airflow obstruction in patients with asthma

According to international guidelines in recent years, it has been proposed that bronchial asthma (BA) with fixed airflow obstructions (FAO) be identified as a separate phenotype.The aimof the study was the clinical and functional characterization and identification of risk factors for the formation of the phenotype BA with FAO.Materials.We examined adult outpatients with BA (n = 432) and a combination of BA and chronic obstructive pulmonary disease (COPD) without exacerbation (n = 58). Anamnesis collection, objective examination, spirometry with the assessment of obstruction reversibility (spirograph 2120 Vitalograph, UK), atopic status assessment (skin samples or specific IgE in serum) were performed. The level of eosinophils and neutrophils in peripheral blood was determined (by the impedance method on the automatic haemoanalyzer). Nitric oxide of exhaled air was measured by a chemiluminescent gas analyzer (Logan 4100, UK). BA control and quality of life of patients were evaluated using the Russian language versions of the Asthma Control Questionnaire (ACQ-5) and the St. George's Hospital Respiratory Questionnaire (St. George's Respiratory Questionnaire – SGRQ) respectively. Statistical analysis was carried out using parametric and non-parametric methods using the application program package Statistica 10. The value of bilateral p &lt; 0.05 was considered statistically significant.Results.Among patients with BA without COPD, the incidence of FAO was 31%, with the most frequent (60%) FAO was found in severe BA and less often – in the mild (7%) and medium (36%) course of the disease. Among patients with a combination of BA and COPD, a severe course of the disease prevailed – 77%. Patients with FAO were older and had a longer duration of disease. The presence of FAO was accompanied by lower rates of pulmonary function, a higher frequency of positive markers of eosinophilic inflammation, worse indicators of control over BA and quality of life, a higher need for “emergency” drugs and drugs to support the treatment of BA, including biological therapy, increased use of healthcare resources. The risk factors for FAO in patients with BA include the debut of BA under 25 years of age (odds ratio (OR) – 1.6), sensitization to ticks of house dust (OR – 1.8), passive smoking (OR – 6.5), suffered during the life of pneumonia (OR - 3.0).Conclusion. The combination of BA + FAO can be considered as a separate phenotype of the disease with a more severe course and less favorable prognosis.

EFFECT OF AIR FLOW OBSTRUCTION IN A CONDENSING UNIT ON SPLIT AIR CONDITIONER PERFORMANCE

Obstructions of air flow in the outdoor unit could block the condenser air flow and reduce its heat rejection As a result, it could decrease the performance of a room air conditioning system. The paper presents the effects of the air flow obstruction of a condensing unit on the performance of a split-type air conditioner with refrigerant R410A. The study was conducted experimentally by employing front and side obstructions with varied distance from the condensing unit. The front obstruction of 100 cm height was applied at varied distance from 10 cm to 100 cm, while the side obstruction of the same height was applied at distance of 5, 10, and 15 cm. The presence of air flow obstructions results in the decrease of cooling capacity and coefficient of performance (COP). On the other hand, it increases the input power of the AC unit. From the experiment, it is obvious that the distance of front obstruction of 10 cm results in the reduction of cooling capacity by 46% and COP by 56%. It is also revealed that the distance of the front obstruction of 50 cm or more has no significant effect for the performance of the air conditioning unit. In addition, the side obstructions have the less significant effect than that of the front obstruction.

A Morphing Cargo Drone for Safe Flight in Proximity of Humans

Delivery drones used by logistics companies today are equipped with unshielded propellers, which represent a major hurdle for in-hand parcel delivery. The exposed propeller blades are hazardous to unsuspecting bystanders, pets, and untrained users. One solution to provide safety is to enclose a drone with an all-encompassing protective cage. However, the structures of existing cage designs have low density in order to minimize obstruction of propeller airflow, so as to not decrease efficiency. The relatively large openings in the cage do not protect hands and fingers from fast rotating propellers. Here we describe a novel approach to safety and aerodynamic efficiency by means of a high-density cage and morphing arms loosely inspired by the box turtle. The drone cage is made of a dense and lightweight grid. When flying in proximity of humans, the arms and propellers are retracted and fully sealed within the cage, thus making the drone safe and also reducing the total footprint. When flying at cruising altitude far from people and objects, the arms and propellers extend out of the protective grid, thus increasing aerodynamic efficiency by more than 20%.

Resistance Exercise and Knee Osteoarthritis

Resistance Exercise and Knee Osteoarthritis

Effectiveness Active Cycle of Breathing Technique (ACBT) with Pursed Lips Breathing Technique (PLBT) to tripod position in increase oxygen saturation in patients with COPD, West Sumatera

Chronic Obstructive Pulmonary Disease (COPD) is a chronic lung disease characterized by obstruction or obstruction of airflow in a reversible or partial nonreversible airway. Dyspnea is a common symptom in COPD sufferers; this can cause problems with oxygen saturation, or the oxygen saturation value is below normal. Non-pharmacological actions given in the form of breathing exercises can be done by a nurse to help reduce shortness of breath in COPD patients. The exercise is given by adjusting the resting position that is comfortable and comfortable so that the extra breath muscles can work well. The position that can do the position of the tripod with Active Cycle of Breathing and Pursed lips are breathing so that shortness of breath is reduced and SaO2 can have increased so that more oxygen has obtained in Lung Hospital, West Sumatra. This research is quantitative research, with quasi-experimental research methods. They used two pre-test-posttest design groups. The sample in this study amounted to 30 people with quota sampling technique. In this study showed that there was a difference in the increase in oxygen saturation of COPD patients which was effective in the tripod position group with Active Cycle Breathing Technique (ACBT) with a p-value of 0.00 while in the tripod position group with the Active Respiratory and Lip Cycle there was a difference of p-value 0.023. It has concluded that the tripod position with ACT and PBLT could increase oxygen saturation and nasal breathlessness reduced, but the tripod position with ACT is more effective in COP patients because with chronic respiratory patients who are short of breath due to sputum buildup, then with ACT will clean the airway and the flow of the road effective breathing so that shortness of breath have reduced and oxygen saturation increases. Furthermore, it has recommended that in hospitals, especially nurses, in dealing with COPD patients in addition to the correct position of breathing exercises with ACT to help patients.

A primer on viral-associated olfactory loss in the era of COVID-19.

Early reports have suggested that smell loss may be an early symptom associated with the pandemic known as coronavirus disease 2019 (COVID‐19). The possibility that severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) might cause olfactory dysfunction is certainly plausible. Patients presenting to specialized smell clinics are commonly diagnosed with upper respiratory infection (URI)‐associated olfactory loss and most are presumed to be viral related. In acute phases of infection, it is common to experience some smell loss as a result of nasal inflammation, mucosal edema, and obstruction of airflow into the olfactory cleft. In most cases, these episodes of smell loss are self‐limiting and coincide with resolution of URI symptoms. However, in some cases the smell loss persists for months to years and this is presumed to occur through a more direct olfactory insult by the virus. It remains too early to know whether infection with SARS‐CoV‐2 causes persistent olfactory dysfunction. However, given the scale of this pandemic, if SARS‐CoV‐2 does cause chronic olfactory loss in even a small portion of those infected, then the overall population prevalence could be quite large. This review provides a brief, practical overview of viral‐associated olfactory loss, realizing that evidence related to COVID‐19 will likely not be clear for some time. Our goal is to highlight the existence and importance of this condition and provide information geared for both providers and patients. Practical suggestions regarding evaluation and treatment will be provided, realizing that there may be constraints on medical resources and the nature of this pandemic remains dynamic.

Study of the relation between speckle tracking echocardiography and BODE index in patients with chronic obstructive pulmonary disease

Background Chronic obstructive pulmonary disease (COPD) is a widespread lung disease with a high mortality and morbidity especially with co-morbid cardiac impairment. Severity of COPD can be assessed using BODE Index (body mass index, obstruction of airflow, dyspnea degree and exercise capacity). Aim To study the relationship between BODE index and right ventricle (RV) and left ventricle (LV) functions using Two-dimensional speckle-tracking echocardiography (2D-STE) in COPD patients. Subjects and methods Fifty stable COPD patients and matched fifty control subjects underwent transthoracic echocardiography, where conventional and speckle tracking parameters were taken. BODE indices were calculated and divided to quartiles (Q) (Q1; BODE index = 0–2, Q2; BODE index = 3–4 Q3; BODE index = 5–6, Q4; BODE index = 7–10). Results COPD patients had lower RV fractional area change (FAC%, P Conclusion COPD patients had RV, LV systolic dysfunction and LV diastolic dysfunction. The more COPD severity increased (assessed by BODE index) the more impairment of RV systolic function and LV diastolic function would be.

Trans-4,4′-dihydroxystilbene ameliorates cigarette smoke-induced progression of chronic obstructive pulmonary disease via inhibiting oxidative stress and inflammatory response

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease resulted from airflow obstructions, and there is a driving requirement for novel and effective preventive and therapeutic agents of COPD. Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been regarded to be a promising therapeutic target for COPD. Resveratrol is a natural Nrf2 activator with antioxidant and anti-inflammatory properties, however, its application is limited by its relative low efficiency and poor bioavailability. Herein, based on the skeleton of resveratrol, trans-4,4′-dihydroxystilbene (DHS) has been firstly identified to be an Nrf2 activator, which is more potent than the well-known sulforaphane (SF) and resveratrol. Our results indicate that DHS blocks Nrf2 ubiquitylation through specifically reacting with Cys151 cysteine in Keap1 protein to activate Nrf2-regulated defensive response, and thus enhances intracellular antioxidant capability. Furthermore, DHS relieves lipopolysaccharide (LPS)-stimulated inflammatory response via inhibition of NF-κB. Importantly, DHS significantly ameliorates pathological alterations (e.g. infiltration of leukocytes and fibrosis), downregulates the levels of oxidant biomarkers malondialdehyde (MDA) and 8-oxo-7,8-dihydro-2′-deoxyguanosin (8-oxo-dG), and inhibits the overproductions of inflammatory mediators [e.g. tumor necrosis factor α (TNF-α), cyclooxygenase-2 (COX-2), and matrix metalloproteinase-9 (MMP-9)] in a cigarette smoke (CS)-induced pulmonary impairment mice model. Taken together, this study demonstrates that DHS attenuates the CS-induced pulmonary impairments through inhibitions of oxidative stress and inflammatory response targeting Nrf2 and NF-κB in vitro and in vivo, and could be developed into a preventive agent against pulmonary impairments induced by CS.

ACUTE ON COPD

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Central Airway Obstruction (CAO) is pathologic obstruction of air flow in the trachea and main stem bronchi. The most common cause of CAO is non-small cell lung cancer, but other common causes are tracheobronchomalacia, tracheal strictures, and other malignancies. Less commonly, primary tumors of the trachea and metastatic cancers can also cause central airway obstruction. CASE PRESENTATION: A 68 year old female with a prior medical history of hypertension, hyperlipidemia, past alcohol dependence, and COPD due to a 45 pack year smoking history presented to the emergency department via EMS. She was intubated for acute hypoxic and hypercapnic respiratory failure and was admitted to the ICU where she underwent treatment for COPD exacerbation, community-acquired pneumonia, and urinary tract infection with azithromycin, methylprednisolone, and ceftriaxone. A review of the patient’s chart showed a screening CT had been completed two days prior to admission and showed a paratracheal mass with invasion into the trachea and right main bronchus. Given the patient’s lack of response to maximal medical therapy, bronchoscopic evaluation was pursued. During bronchoscopy, a mass was found protruding from the right main stem bronchus, occluding 80-90% of the trachea. The bronchoscope could not be passed around the mass, however biopsies were taken before the procedure was aborted. Interventional Pulmonology was consulted with plans for further evaluation and management. The patient underwent a second bronchoscopic evaluation, which showed near occlusion of the trachea due to tumor in the left main stem bronchus. Debulking provided rapid improvement in oxygen saturation. Further debulking of the trachea and right main stem bronchus were completed with rigid bronchoscopy and a stent was placed at the entrance of the right main stem to prevent further airway collapse. The following day, the patient was successfully extubated without further respiratory difficulties. She was transferred from the ICU to the general medical floor and ultimately to a rehabilitation facility with Oncology follow up. The patient has quit smoking, follows at UW medicine for her sarcoma, and is handling her symptoms well. DISCUSSION: Pathology on the specimens obtained showed poorly differentiated synovial sarcoma. Synovial sarcoma most commonly affects children and young adults. It routinely affects the knees and ankles but can involve other joints. It is normally found proximal to tendons and bursae without invasion of surrounding tissues, joint space, or synovial membranes. Case reports have described synovial sarcoma in almost all anatomical locations despite its predilection for synovial joints. CONCLUSIONS: Obstructive lung disease can have multiple causes, therefore it is important to consider that respiratory failure may be secondary to more than just a patient’s known underlying lung pathology. Reference #1: Herth, Felix JF. (2018). Clinical Presentation, diagnostic Evaluation, and management of central airway obstruction in adults. G. Finlay (Ed.), UpToDate. Retrieved March 10, 2019, from https://www.uptodate.com/contents/clinical-presentation-diagnostic-evaluation-and-management-of-central-airway-obstruction-in-adults Reference #2: Goldblum, John R. Rosai and Ackerman’s Surgical Pathology, 11th ed. Elsevier Inc. C2018. Chapter 41, Soft Tissues; p. 1810-1914. Reference #3: David Feller-Kopman, Atul C. Mehta and Momen M. Wahidi. Murray and Nadel's Textbook of Respiratory Medicine. 6th ed. Saunders. c2016. Chapter 23, Therapeutic Bronchoscopy; p. 383-392. DISCLOSURES: no disclosure on file for Jonathan Danaraj; No relevant relationships by Matthew Strohmeyer, source=Web Response

Pemilihan Bronkodilator Pada Penyakit Paru Obstruktif Kroni

Chronic obstructive pulmonary disease (COPD) is a disease that is often found, can be prevented and treated. It characterized by symptoms of persistent respiration and obstruction of airflow, associated with airway disorders and/or alveoli due to exposure to significant harmful particles or gases. COPD currently causes the world's fourth death and is projected to be third in 2020. In 2012, COPD has caused 3 million deaths (6% of all deaths) and will contribute 4.5 million deaths by 2030. COPD requires high costs especially in exacerbation conditions that require hospital treatment.Exposure to cigarette smoke or harmful agents will cause stimulation of macrophages and airway epithelium. Stimulation of macrophages will stimulate inflammatory processes and the underlying cascade such as protease formation and increased oxidative stress. One treatment of COPD is through pharmacological therapy approaches using a bronchodilator which aims to overcome airflow limitation with or without the addition of corticosteroids, mucolytics, antioxidants, and other drugs. The choice of bronchodilators in COPD patients is very individual. The selection must pay attention to the degree of the complaint, the magnitude of the risk of exacerbation, side effects, drug availability, costs, the presence of comorbid diseases and device inhalers.

The airway epithelium in asthma.

Asthma is a genetically and phenotypically complex disease that has a major impact on global health. Signs and symptoms of asthma are caused by the obstruction of airflow through the airways. The epithelium that lines the airways plays a major role in maintaining airway patency and in host defense. The epithelium initiates responses to inhaled or aspirated substances, including allergens, viruses, and bacteria, and epithelial-derived cytokines are important in the recruitment and activation of immune cells in the airway. Changes in the structure and function of the airway epithelium are a prominent feature of asthma. Approximately half of individuals with asthma have evidence of active type 2 immune responses in the airway. In these individuals, epithelial cytokines promote type 2 responses, and responses to type 2 cytokines result in increased epithelial mucus production and other effects that cause airway obstruction. Recent work also implicates other epithelial responses, including interleukin-17, interferon and ER stress responses, that may contribute to asthma pathogenesis and provide new targets for therapy.

Wind-driven natural ventilation of greenhouses with vegetation

A large eddy simulation (LES) model was used to examine the wind-driven cross ventilation of gable-roof greenhouses containing vegetation. The obstruction of air flow by vegetation was described by a porous drag model in the numerical model, and the simulation results were validated using wind tunnel experiments. The numerical model was then utilised to inspect the influences of vegetation and greenhouse length (in the wind direction) on the ventilation rate. The results revealed that the diminishing effects of the vegetation, insect screen and internal friction on the ventilation rate can all be quantified by a physical-based resistance model. The driving force (the difference between windward and leeward pressures) of long, multi-span greenhouses was found to be less than that of a short, single-span greenhouse leading to a lower ventilation rate. The resistance factor of the vegetation and the insect screen depends on their porosity, while the resistance factor of the internal friction increased as the greenhouse length increased. In addition, the internal friction of multi-span greenhouses should be considered when the length of the greenhouse was greater than six times the greenhouse height.