Technique to Determine Inspiratory Impedance during Mechanical Ventilation: Implications for Flow Limited Patients

We present the design of an enhanced ventilator waveform (EVW) for routine measurement of inspiratory resistance (R) and elastance (E) spectra in ventilator-dependent and/or severely obstructed flow-limited patients. The EVW delivers an inspiratory tidal volume of fresh gas with a flow pattern consisting of multiple sinusoids from 0.156 to 8.1 Hz and permits a patient-driven exhalation to the atmosphere or positive end-expiratory pressure. Weighted least-squares estimates of the coefficients in a sinusoidal series approximation of the EVW inspirations yielded inspiratory R and E spectra. We first validated the EVW approach using simulated pressure and flow data under different physiological conditions, noise levels, and harmonic distortions. We then applied the EVW in four intubated patients during anesthesia and paralysis: two with mild airway obstruction and two with severe emphysema and flow limitation. While the level of inspiratory R was similar in both groups of patients, the inspiratory E of the emphysematous patients demonstrated a pronounced frequency-dependent increase consistent with severe peripheral airway obstruction. We conclude that the EVW offers a potentially practical and efficient approach to monitor lung function in ventilator-dependent patients, especially those with expiratory flow limitation. © 1999 Biomedical Engineering Society. PAC99: 8719Uv, 8780-y     

How Heterogeneous Bronchoconstriction Affects Ventilation Distribution in Human Lungs: A Morphometric Model

Convective dependent flow heterogeneities associated with airways proximal to the acini are the dominant cause of abnormal ventilation distribution during induced bronchoconstriction (Verbanck, S., D. Schuermans, A. Van Muylem, M. Paira, M. Noppen, and W. Vincken. Ventilation distribution during histamine provocation. J. Appl. Physiol. 83:1907–1916, 1997). We applied a morphometric model of the human lung to predict flow distributions among the acini during heterogeneous bronchoconstriction and relate these distributions to impairments in the mechanical properties of the lung. The model has an asymmetrical branching airway system. Heterogeneous constriction was invoked by defining an airway constriction distribution with a mean () and coefficient of variation (CV) and either a Gaussian or log normal distribution. The lung resistance (R _L ) and elastance E _L were most sensitive to severely heterogeneous constriction that produced a few highly constricted or closed airways dispersed randomly throughout the periphery. Ventilation distribution in the healthy lung was effectively homogeneous over the frequency range of 0.1–5.0 Hz. With homogeneous or mildly heterogeneous constriction (CV20%) ventilation remained fairly homogeneous at low frequencies (0.1 Hz) but rapidly became heterogeneous as frequency increased. Conversely, a low mean but severely heterogeneous constriction that produced random airway closure produced abnormal ventilation distribution in most acini at all frequencies, and some acini received up to 25 times the normal ventilation. This suggests that certain forms of heterogeneity can lead to shear induced lung injury even at common mechanical ventilation rates. © 1999 Biomedical Engineering Society. PAC99: 8710+e, 8719Uv, 8719Rr     

Relation Between Structure,Function, and Imaging in a Three-Dimensional Model of the Lung

Previous studies have reported morphometric models to predict function relations in the lung. These models, however, are not anatomically explicit. We have advanced a three-dimensional airway tree model to relate dynamic lung function to alterations in structure, particularly when constriction patterns are imposed heterogeneously in specific anatomic locations. First, we predicted the sensitivity of dynamic lung resistance and elastance R _L and E _L ) to explicit forms of potential constriction patterns. Simulations show that severe and heterogeneous peripheral airway constriction confined to a single region in the lung (apex, mid, or base) will not produce substantial alterations in whole lung properties as measured from the airway opening. Conversely, when measured R _L and E _L are abnormal, it is likely that significant (but not necessarily homogeneous) constriction has occurred throughout the entire airway tree. We also introduce the concept of image-assisted modeling. Here positron emission tomographic imaging data sensitive to ventilation heterogeneity is synthesized with R _L and E _L data to help identify which airway constriction conditions could be consistent with both data sets. An ultimate goal would be personalized predictions. © 2003 Biomedical Engineering Society. PAC2003: 8719Uv, 8710+e, 8758Fg     

The Estimation of Lung Mechanics Parameters in the Presence of Pathology: A Theoretical Analysis

Mechanical lung function is frequently assessed in terms of lung resistance (R _L), lung elastance (E _L), and airway resistance (R _aw). These quantities are determined by measuring input impedance at various oscillation frequencies, and allow lung tissue resistance (R _t) to be estimated as the difference between R _L and R _aw. These various parameters change in characteristic ways in the presence of lung pathology. In particular, the ratio R _t/E _L (known as hysteresivity, (η) has been shown both experimentally and in numerical simulations to increase when regional heterogeneities in mechanical function develop throughout the lung. In this study, we performed an analytical investigation of a two-compartment lung model and showed that while heterogeneity always leads to an increase in E _L, η will increase only initially. When heterogeneity becomes extreme, η stops increasing and starts to decrease. However, there are no experimental reports of η decreasing under conditions in which heterogeneity would be expected to exist. We speculate that this is because liquid bridges invariably form across airway lumen that narrow to a certain point, thereby preventing them from achieving arbitrarily small non-zero radii. We also show that recruitment of closed lung units during lung inflation may lead to variables responses in both η and E _L.     

Optimal Tracheal Tube Cuff Inflation in Infants: Implications for Mechanical Ventilation and Respiratory Mechanics

Uncuffed tracheal tubes (TT) are used to intubate infants and children to avoid laryngotracheal tissue injury. The geometric mismatch resulting from such intubation limits the efficacy of mechanical ventilation, and reliability of derived respiratory mechanical properties. This study tested the hypotheses that (1) normal stresses applied to the cuff surface by leak flows during ventilation result in intracuff pressure (P _cuff) fluctuations proportionate to leak magnitudes, and (2) these fluctuations reach a steady minimum when cuff volume reaches a critical value V _crit at which the TT–airway mismatch is removed. Physical model and piglet measurements showed that, during simultaneous cuff inflation and mechanical ventilation, P _cuff consisted of a leak-dependent P _cuff,1 component that cycles with the ventilator superimposed on a ramp rise due to cuff inflation. The breath-to-breath peak P _cuff,1 (max P _cuff)decreased as leak flows are reduced, and these were relatively greater for higher ventilator flows and when the load impedance is increased such as by disease. These results describe a reproducible method of TT cuff inflation that removes leaks without increased risk of laryngotracheal tissue injury. Moreover, inflation of the TT cuff more securely improved ventilation efficacy and allowed for accurate respiratory mechanics. © 2001 Biomedical Engineering Society. PAC01: 8719Uv, 8780-y     

Reliability of Estimating Stochastic Lung Tissue Heterogeneity from Pulmonary Impedance Spectra: A Forward-Inverse Modeling Study

Heterogeneity of regional lung mechanics is an important determinant of the work of breathing and may be a risk factor for ventilator associated lung injury. The ability to accurately assess heterogeneity may have important implications for monitoring disease progression and optimizing ventilator settings. Inverse modeling approaches, when applied to dynamic pulmonary impedance data (Z _L), are thought to be sensitive to the detection of mechanical heterogeneity with the ability to characterize global lung function using a minimal number of free parameters. However, the reliability and bias associated with such model-based estimates of heterogeneity are unknown. We simulated Z _L spectra from healthy, emphysematous, and acutely injured lungs using a computer-generated anatomic canine structure with asymmetric Horsfield branching and various predefined distributions of stochastic lung tissue heterogeneity. Various inverse models with distinct topologies incorporating linear resistive and inertial airways with parallel tissue viscoelasticity were then fitted to these Z _L spectra and evaluated in terms of their quality of fit as well as the accuracy and reliability of their respective model parameters. While all model topologies detected appropriate changes in tissue heterogeneity, only a topology consisting of lumped airway properties with distributed tissue properties yielded accurate estimates of both mean lung tissue stiffness and the spread of regional elastances. These data demonstrate that inverse modeling approaches applied to noninvasive measures of Z _L may provide reliable and accurate assessments of lung tissue heterogeneity as well as insight into distributed lung mechanical properties. Address correspondence to David W. Kaczka, Division of Obstetric and Regional Anesthesia, Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Hospital, 600 North Wolfe Street, Meyer 299C, Baltimore, MD 21287, USA. Electronic mail: dkaczka1@jhmi.edu An erratum to this article can be found at     

Assessment of time-domain analyses for estimation of low-frequency respiratory mechanical properties and impedance spectra

Time-domain estimation has been invoked for tracking of respiratory mechanical properties using primarily a simple single-compartment model containing a series resistance (R _rs) and elastance (E _rs). However, owing to the viscoelastic properties of respiratory tissues,R _rs andE _rs exhibit frequency dependence below 2 Hz. The goal of this study was to investigate the bias and statistical accuracy of various time-domain approaches with respect to model properties, as well as the estimated impedance spectra. Particular emphasis was placed on establishing the tracking capability using a standard step ventilation. A simulation study compared continuous-timeversus discrete-time approaches for both the single-compartment and two-compartment models. Data were acquired in four healthy humans and two dogs before and after induced severe pulmonary edema while applying sinusoidal and standard ventilator forcing.R _rs andE _rs were estimated either by the standard Fast Fourier Transform (FFT) approach or by a time-domain least square estimation. Results show that the continuous-time model form produced the least bias and smallest parameter uncertainty for a single-compartment analysis and is quite amenable for reliable on-line tracking. The discrete-time approach exhibits large uncertainty and bias, particularly with increasing noise in the flow data. In humans, the time-domain approach produced smooth estimates ofR _rs andE _rs spectra, but they were statistically unreliable at the lower frequencies. In dogs, both the FFT and time-domain analysis produced reliable and stable estimates forR _rs orE _rs spectra for frequencies out to 2 Hz in all conditions. Nevertheless, obtaining stable on-line parameter estimates for the two-compartment viscoelastic models remained difficult. We conclude that time-domain analysis of respiratory mechanics should invoke a continuous-time model form.     

Allergen-induced airway responses in rats pretreated with Sephadex

Even though the eosinophil is potentially an important contributor to airway narrowing during the late allergic airway response, direct evidence of its participation is lacking. Therefore, we examined the effects of eosinophilia induced by Sephadex on the magnitude of the late airway response of sensitized rats following allergen challenge. Brown Norway rats were actively sensitized to ovalbumin (OA). At the same time and 14 days later, a test group was administered Sephadex G200 (0.5 mg intravenously). The animals were challenged with an aerosol of OA and pulmonary resistance (R _L) was measured over 6 h. The early response to OA reached a peak more rapidly and the magnitude of the late response, measured as the area under the curve ofR _L against time, was significantly greater in the Sephadex-treated group (48.3; geometric mean) compared to the control animals (18.9;p<0.02). The percentage of eosinophils was increased in the bronchoalveolar lavage of Sephadex-treated animals (4%) compared to the controls (0.9%;p<0.02) following OA challenge. These results demonstrate that Sephadex induces eosinophilia in Brown Norway rats and is associated with an increase in the late allergic airway response. This is consistent with the hypothesis that the eosinophil is an important determinant of the late response.     

Bopindolol, pindolol, and atenolol in patients with chronic obstructive lung disease

Summary Twelve subjects with chronic obstructive lung disease and a partially reversible obstruction received increasing single doses of bopindolol (1, 2, 4, and 8 mg), pindolol (7.5, 15, and 30 mg), and atenolol (50 and 100 mg). Resting heart rate and blood pressure were reduced in a dose-dependent fashion. The actions of the drugs on lung function were assessed by whole body plethysmography. Pindolol did not influence mean airway resistance (R _aw). Bopindolol (1, 2 and 4 mg) and atenolol (50 mg) exhibited a neutral effect on meanR _aw. Atenolol (100 mg) and to a lesser extent bopindolol (8 mg) induced a long-lasting increase in mean R_aw.Abbreviations R_aw airway resistance - HR heart rate     

Different strains of mice present distinct lung tissue mechanics and extracellular matrix composition in a model of chronic allergic asthma

The impact of genetic factors on asthma is well recognized but poorly understood. We tested the hypothesis that different mouse strains present different lung tissue strip mechanics in a model of chronic allergic asthma and that these mechanical differences may be potentially related to changes of extracellular matrix composition and/or contractile elements in lung parenchyma. Oscillatory mechanics were analysed before and after acetylcholine (ACh) in C57BL/10, BALB/c, and A/J mice, subjected or not to ovalbumin sensitization and challenge. In controls, tissue elastance (E) and resistance (R), collagen and elastic fibres’ content, and α-actin were higher in A/J compared to BALB/c mice, which, in turn, were more elevated than in C57BL/10. A similar response pattern was observed in ovalbumin-challenged animals irrespective of mouse strain. E and R augmented more in ovalbumin-challenged A/J [E: 22%, R: 18%] than C57BL/10 mice [E: 9.4%, R: 11%] after ACh In conclusion, lung parenchyma remodelled differently yielding distinct in vitro mechanics according to mouse strain.     

Assessment of upper airway mechanics during sleep

Obstructive sleep apnea, which is the most prevalent sleep breathing disorder, is characterized by recurrent episodes of upper airway collapse and reopening. However, the mechanical properties of the upper airway are not directly measured in routine polysomnography because only qualitative sensors (thermistors for flow and thoraco-abdominal bands for pressure) are used. This review focuses on two techniques that quantify upper airway obstruction during sleep. A Starling model of collapsible conduit allows us to interpret the mechanics of the upper airway by means of two parameters: the critical pressure (P_crit) and the upstream resistance (R_up). A simple technique to measure P_crit and R_up involves the application of different levels of continuous positive airway pressure (CPAP) during sleep. The forced oscillation technique is another non-invasive procedure for quantifying upper airway impedance during the breathing cycle in sleep studies. The latest developments in these two methods allow them to be easily applied on a routine basis in order to more fully characterize upper airway mechanics in patients with sleep breathing disorders.     

Repeated aeroallergen challenge induces lung dysfunction but not bronchial hyperresponsiveness in conscious guinea pigs

Adult male Hartley-strain guinea pigs were sensitized by 10 min exposure to aerosolized 1% ovalbumin (OA; 10 mg/ml in normal saline containing 4% heat-killedB. pertussis vaccine and 0.02% antifoam B emulsion). One week after sensitization, animals were placed in an exposure chamber and challenged (nebulized OA 0.5%) until each animal showed labored breathing. Maximal exposure time was 10 min. Diphenhydramine (20 mg/kg, i.p.) was given 1 h before each OA challenge to protect the animals from bronchospasmic death. Antigen challenge was repeated twice a week for 2 weeks. The specific airway resistance (sR _aw) changes in response to increasing concentrations of aerosolized acetylcholine (Ach) were determined. The data obtained in this study demonstrated that repeated antigen challenge produced a significant bronchial tone i.e. an increase in sR _aw and a decline in specific airway conductance (sG _aw) and failed to induce bronchial hyperreactivity to aerosolized acetylcholine (Ach) in conscious guinea pigs.     

Exercise stimulus increases ventilation from maximal to supramaximal intensity

This study investigated the influence of an exercise stimulus on pulmonary ventilation (V _E) during severe levels of exercise in a group of ten athletes. The altered ventilation was assessed in relation to its effect on blood gas status, in particular to the incidence and severity of exercise induced hypoxaemia. Direct measurements of arterial blood were made at rest and during the last 15 s of two intense periods of cycling; once at an intensity found to elicit maximal oxygen uptake (VO_2max; MAX) and once at an intensity established to require 115% ofVO_2max (SMAX). Oxygen uptake (VO₂) and ventilatory markers were continually recorded during the exercise and respiratory flow-volume loops were measured at rest and during the final 30 s of each minute for both exercise intensities. When compared to MAX exercise, the subjects had higher ventilation and partial pressure of arterial oxygen (P _aO₂) during the SMAX intensity. Regression analysis for both conditions indicated the levels ofP _aO₂ and oxygen saturation of arterial blood (S _aO₂) were positively correlated with relative levels of ventilation during exercise. It was apparent that mechanical constraints to ventilate further were not present during the MAX test since the subjects were able to elevateV _E during SMAX and attenuate the level of hypoxaemia. This was also confirmed by analysis of the flow volume recordings. These data support the conclusions firstly, that overwhelming mechanical constraints onV _E were not present during the MAX exercise, secondly, the subjects exhibiting the most severe hypoxaemia had no consistent relationship with any measure of expiratory flow limitation, and thirdly, ventilatory patterns during intense exercise are strong predictors of blood gas status.     

Impact of Positive End-Expiratory Pressure During Heterogeneous Lung Injury: Insights from Computed Tomographic Image Functional Modeling

Image Functional Modeling (IFM) synthesizes three dimensional airway networks with imaging and mechanics data to relate structure to function. The goal of this study was to advance IFM to establish a method of exploring how heterogeneous alveolar flooding and collapse during lung injury would impact regional respiratory mechanics and flow distributions within the lung at distinct positive end-expiratory pressure (PEEP) levels. We estimated regional respiratory system elastance from computed tomography (CT) scans taken in 5 saline-lavaged sheep at PEEP levels from 7.5 to 20 cmH₂O. These data were anatomically mapped into a computational sheep lung model, which was used to predict the corresponding impact of PEEP on dynamic flow distribution. Under pre-injury conditions and during lung injury, respiratory system elastance was determined to be spatially heterogeneous and the values were distributed with a hyperbolic distribution in the range of measured values. Increases in PEEP appear to modulate the heterogeneity of the flow distribution throughout the injured lung. Moderate increases in PEEP decreased the heterogeneity of elastance and predicted flow distribution, although heterogeneity began to increase for PEEP levels above 12.5–15 cmH₂O. By combining regional respiratory system elastance estimated from CT with our computational lung model, we can potentially predict the dynamic distribution of the tidal volume during mechanical ventilation and thus identify specific areas of the lung at risk of being overdistended.     

In Silico Ventilation Within the Dose-Volume is Predictive of Lung Function Post-radiation Therapy in Patients with Lung Cancer

Lung cancer is a leading cause of death worldwide. Radiation therapy (RT) is one method to treat this disease. A common side effect of RT for lung cancer is radiation-induced lung damage (RILD) which leads to loss of lung function. RILD often compounds pre-existing smoking-related regional lung function impairment. It is difficult to predict patient outcomes due to large variability in individual response to RT. In this study, the capability of image-based modelling of regional ventilation in lung cancer patients to predict lung function post-RT was investigated. Twenty-five patient-based models were created using CT images to define the airway geometry, size and location of tumour, and distribution of emphysema. Simulated ventilation within the 20 Gy isodose volume showed a statistically significant negative correlation with the change in forced expiratory volume in 1 s 12-months post-RT (p?=?0.001, R?=?? 0.61). Patients with higher simulated ventilation within the 20 Gy isodose volume had a greater loss in lung function post-RT and vice versa. This relationship was only evident with the combined impact of tumour and emphysema, with the location of the emphysema relative to the dose-volume being important. Our results suggest that model-based ventilation measures can be used in the prediction of patient lung function post-RT.

     

Lung mechanics are both dose and tidal volume dependant in LPS-induced lung injury

Endotoxin stimulus plays a significant role in various forms of acute lung injury (ALI) which may be exacerbated by mechanical ventilation. Here, we identify the temporal pathophysiologic sequence following inhaled lipopolysaccharide (LPS) and subsequently examine both LPS dose and V_T relationships. Rats received intratracheal LPS (3, 9 or 15 mg/kg) prior to mechanical ventilation (V_T = 6, 9 or 12 ml/kg) and measurement of forced impedance mechanics for up to 4 h. LPS-induced lung injury was achieved within the 15 min of LPS instillation with a 78% decrease in PaO₂ promptly followed by 30% deterioration in tissue elastance. Despite a 41% increase in total surfactant, the active disaturated phospholipid fraction decreased 3–7% with decreasing PaO₂ and tissue mechanics and with increases in total lung lavage protein (150%) and wet-to-dry lung weight ratio (10%). V_T = 12 ml/kg resulted in an additional deterioration in tissue resistance (130%) and elastance (63%). These results suggest that LPS-induced lung injury is both LPS dose and V_T sensitive, supporting a ‘two hit’ model of ALI.     

Respiratory input impedance measurement: Forced oscillation methods

The paper reviews how forced oscillation techniques (FOT) for measuring respiratory input impedance Z_{rs, in} have recently been used in clinical applications. Z_{rs, in} is clinically relevant, as it provides data on both the resistive, R_rs, and nonresistive, X_rs, components of the respiratory system. Additionally, when excitatory test signals extending into low- (<4 Hz) or high-frequency (>100 Hz) ranges are used, reliable partitioning of lung tissue from airway components is feasible. Adult and paediatric studies examining the use of Z_{rs, in} for routine lung-function assessment, sleep and mechanical ventilation are reviewed. For clinicians, Z_{rs, in} is repeatable and sensitive to airway resistance. It is helpful for assessing unco-operative and severely obstructed patients, for monotoring mechanics during artificial ventilation and for tracking airway closure during sleep studies. For paediatricians, longitudinal studies of the growth and development of the respiratory system can also be made using Z_{rs, in}. Forced oscillation techniques, however, require further standardisation, and Z_{rs, in} is limited by upper-airway shunt artifacts. In conclusion, measurement of Z_{rs, in} using FOT is an important and sophisticated non-invasive lung-function test, showing good potential for future clinical applications.     

Role of eicosanoids in airflow obstruction and airway plasma exudation induced by trimellitic anhydride-conjugate in guinea-pigs 3 and 8 weeks after sensitization

Abstract. Trimellitic anhydride (TMA) is a low molecular weight chemical which can cause occupational asthma. We studied the role of eicosanoids in airway responses to TMA at different times after sensitization in actively sensitized guinea-pigs. Sensitization was performed by two intradermal injections of free TMA (0.1 ml of 0.3% TMA in corn oil). At 3 and 8 weeks after sensitization, the guinea-pigs were anaesthetized and challenged with intratracheal instillation of 0.5% TMA conjugated to guinea-pig serum albumin (TM A-GPSA; 50 μl). Lung resistance (RL) was measured to assess airflow obstruction, and the tissue content of Evans Blue dye was measured to assess airway plasma exudation. Intratracheal instillation of TMA-GPSA induced a slowly progressing increase in R_L, reaching a peak at approximately 3.5 min after the challenge (6.0 ± 2.0cm H₂O/ml/s in the 3-week group and 3.8 + 0.6 in the 8-week group). Pretreatment before challenge with pyrilamine (anti-histamine: 2 mg/kg. intravenously) slowed the onset of the increase in R_L following challenge with TMA-GPSA, and significantly attenuated the peak response. A combination of pyrilamine and IC1-192, 605 (thromboxane receptor antagonist; 0.5 mg/kg, intravenously) completely abolished the increase in R_Lin both week groups. A combination of pyrilamine and ICI-198, 615 (leukotrieneC₄/D₄/ E₄ receptor antagonist: 0.5 mg/kg, intravenously) did not further attenuate the increase in R_L compared with pretreatment with pyrilamine alone, but the induced Evans Blue dye extravasation was completely inhibited in the 3-week group, whereas a remaining extravasation was observed in the 8-week group. We conclude that the bronchoconstrictor response to TMA-GPSA in actively sensitized guinea-pigs is mediated by histamine and thromboxane A₂ both early and late after sensitization, whereas leukotrienes and histamine partially mediate TMA-induced airway plasma exudation.     

A new infant hybrid respiratory simulator: preliminary evaluation based on clinical data

A new hybrid (numerical–physical) simulator of the respiratory system, designed to simulate spontaneous and artificial/assisted ventilation of preterm and full-term infants underwent preliminary evaluation. A numerical, seven-compartmental model of the respiratory system mechanics allows the operator to simulate global and peripheral obstruction and restriction of the lungs. The physical part of the simulator is a piston-based construction of impedance transformer. LabVIEW real-time software coordinates the work of both parts of the simulator and its interaction with a ventilator. Using clinical data, five groups of “artificial infants” were examined: healthy full-term infants, very low-birth-weight preterm infants successfully (VLBW) and unsuccessfully extubated (VLBWun) and extremely low-birth-weight preterm infants without (ELBW) and with bronchopulmonary dysplasia (ELBW_BPD). Pressure-controlled ventilation was simulated to measure peak inspiratory pressure, mean airway pressure, total (patient + endotracheal tube) airway resistance (R), total dynamic compliance of the respiratory system (C), and total work of breathing by the ventilator (WOB). The differences between simulation and clinical parameters were not significant. High correlation coefficients between both types of data were obtained for R, C, and WOB (γ _R  = 0.99, P < 0.0005; γ _C  = 0.85, P < 0.005; γ_WOB = 0.96, P < 0.05, respectively). Thus, the simulator accurately reproduces infant respiratory system mechanics.     

Airway response to emotion‐ and disease‐specific films in asthma,blood phobia,and health

Earlier research found autonomic and airway reactivity in asthma patients when they were exposed to blood‐injection‐injury (BII) stimuli. We studied oscillatory resistance (R_os) in asthma and BII phobia during emotional and disease‐relevant films and examined whether muscle tension counteracts emotion‐induced airway constriction. Fifteen asthma patients, 12 BII phobia patients, and 14 healthy controls viewed one set of negative, positive, neutral, BII‐related, and asthma‐related films with leg muscle tension and a second set without. R_os, ventilation, cardiovascular activity, and skin conductance were measured continuously. R_os was higher during emotional compared to neutral films, particularly during BII material, and responses increased from healthy over asthmatic to BII phobia participants. Leg muscle tension did not abolish R_os increases. Thus, the airways are particularly responsive to BII‐relevant stimuli, which could become risk factors for asthma patients.