Altered Breathing Pattern Research Articles

Influence of prenatal nicotine exposure on postnatal development of breathing pattern.

To determine if prenatal nicotine exposure alters the postnatal development of the ventilatory pattern and the frequency and duration of apneas, we recorded respiratory airflow with head-out body plethysmography in awake neonates on postnatal days 1, 2, 6, 10, 14, and 18. Data from 12 nicotine-exposed animals were compared with data from 12 saline-exposed animals. Nicotine (6 mg/kg of nicotine tartrate per day) or saline exposure was induced by osmotic minipumps that were implanted subdermally on the fifth day of gestation in Sprague-Dawley Dams. Although both saline- and nicotine-exposed pups gained weight at the same rate throughout the studies, there were subtle differences in ventilatory indices between the two groups. Nicotine-exposed animals had a significantly higher breathing frequency on day 10, and a lower tidal volume on days 14 and 18. Although ventilation tended to be lower in the nicotine-exposed animals, the difference was not significant. There was a significantly higher frequency of apneas in the nicotine-exposed compared with the saline-exposed animals on postnatal days 1 and 2, but the apnea duration did not differ between the groups. No apneas were observed in any of the animals after the sixth postnatal day. Prenatal nicotine exposure is associated with a greater incidence of apneas on the first two postnatal days, and then an altered breathing pattern that manifests at a later stage of development.

Arm work interferes with normal ventilation

Arm work, by limiting movement of the chest wall and use of the respiratory muscles, may alter breathing pattern and gas exchange sufficiently to interfere with the ability to perform certain tasks. To determine the effects of arm work on breathing pattern during a well-controlled work task, depth of breathing, breathing frequency and end-expiratory lung volume (EELV) were measured at rest and during cycling exercise using an arm and a leg ergometer. Six subjects performed arm work at light, moderate and heavy intensities (30%, 60% and 90% of maximum arm work capacity respectively) and leg work at three intensities where ventilation was matched for that achieved during the arm work. This matching was necessary since the level of ventilation affects the breathing pattern. Subjects breathed on a mouthpiece and tubing that led to automated equipment for the measurement of respiratory variables. Ventilation during arm work was accomplished with a lower depth of breathing, a higher breathing frequency and a decreased EELV compared to leg work. Arm work places increased demands on the ventilatory system, including the muscles of respiration that are also recruited for task performance. The competition for using these muscles for breathing as opposed to a particular work task may result in a compromise in breathing capacity that ultimately may limit the ability to perform tasks requiring sustained heavy use of the arms. These increased demands on the upper body muscles must be considered when evaluating the ability of individuals to perform tasks that involve heavy arm work.

Respiratory Allergy to Trimellitic Anhydride in Rats: Concentration-Response Relationships During Elicitation

The present study investigated whether airway responses of sensitized rats to trimellitic anhydride (TMA) were concentration dependent and whether these were related to irritation by TMA. Groups of BN and Wistar rats were sensitized by two dermal applications of TMA (50% w/v, followed by 25% w/v in vehicle). Controls received vehicle (acetone–olive oil 4:1, v/v). All animals were challenged 3 wk after the first sensitization by inhalation of one of a range of concentrations of TMA (0.2–61 mg/m3 for BN rats, 15–250 mg/m3 for Wistar rats). Breathing pattern, breathing frequency, and tidal volume were measured before, during, and after challenge to assess allergic and irritative airway responses. One day after challenge, nonspecific airway responsiveness to a range of concentrations of methacholine was measured. At necropsy on the same day, blood was withdrawn for measuring total serum immunoglobulin E (IgE) and organs were weighed. Larynx, trachea and lungs were examined histopathologically. In BN rats, TMA sensitization elevated total IgE levels; subsequent inhalation challenge with 2 mg/m3 of TMA and higher caused laryngeal inflammation with squamous epithelial metaplasia, and pulmonary hemorrhages. Concentration-related decreases in breathing frequency and alterations in breathing pattern, which differed from the irritation-induced pattern, were also observed at these levels. Inhalation challenge with TMA concentrations of 12 mg/m3 and higher increased lung weight. Increased nonspecific airway responsiveness was observed at the 2 next higher tested concentrations of 46 and 61 mg/m3. In unsensitized BN rats, only laryngeal squamous metaplasia was observed, albeit at higher challenge concentrations of TMA, and decreased breathing frequency, a typical breathing pattern characteristic of irritation. Identically sensitized Wistar rats showed airway inflammation and pulmonary hemorrhages upon challenge with TMA, but no functional changes, even at distinctly irritating concentrations of TMA up to 250 mg/m3. In conclusion, TMA challenge of sensitized BN rats caused challenge concentration-related allergic airway inflammation, asthmalike changes in breathing pattern, and increased nonspecific airway responsiveness. The lowest no-observed-effect level (NOEL) based on the most sensitive endpoint investigated was 0.2 mg/m3, a value that is well below the irritation concentration. The presence of a NOEL in the sensitized BN rat suggests that assessment of safe human exposure levels is feasible.

Effects of Muscle Training on Breathing Pattern in Patients With Severe Chronic Obstructive Pulmonary Disease

During physical exertion, the ventilatory response of patients with severe chronic obstructive pulmonary disease (COPD) is more rapid and shallow than that of healthy subjects. There is evidence that exercise training can alter breathing pattern in COPD patients. The purpose of the present study was to observe the effects of physical training on patients with severe COPD and to determine whether or not any possible changes were maintained over time. Patients with severe COPD without bronchial reversibility were enrolled in a randomized controlled trial of a peripheral muscle training program carried out in a hospital setting. All enrolled patients were clinically stable, without exacerbation, and were randomly assigned to a training program of high (group A) or low (group B) intensity. Thirty-five men with severe COPD in stable condition (mean [SD] forced expiratory volume in 1 second at 41%[7%]) were enrolled in the study. The mean age was 64(5) years. Group A underwent training at 70(22) W and group B at 35(10) W, such that the estimated total work was 8050(2882) kJ in group A and 4044(1205) kJ in group B. Breathing pattern changes were detected in exercise tests only for group A patients, but the changes were not maintained 12 months after the end of the program. Intense training produces changes in the breathing pattern of patients with severe COPD. The changes are not specific to the task performed, not dependent on lactate production, and not maintained over the long term.

Immediate sensory nerve-mediated respiratory responses to irritants in healthy and allergic airway-diseased mice.

The immediate responses of the upper respiratory tract (URT) to the irritants acrolein and acetic acid were examined in healthy and allergic airway-diseased C57Bl/6J mice. Acrolein (1.1 ppm) and acetic acid (330 ppm) vapors induced an immediate increase in flow resistance, as measured in the surgically isolated URT of urethane-anesthetized healthy animals. Acrolein, but not acetic acid, induced a small URT vasodilatory response. In awake spontaneously breathing mice, both vapors induced a prolonged pause at the start of expiration (a response mediated via stimulation of nasal trigeminal nerves) and an increase in total respiratory specific airway flow resistance, the magnitude of which was similar to that observed in the isolated URT. Both responses were significantly reduced in animals pretreated with large doses of capsaicin to defunctionalize sensory nerves, strongly suggesting a role for sensory nerves in development of these responses. The breathing pattern and/or obstructive responses were enhanced in mice with ovalbumin-induced allergic airway disease. These results suggest that the primary responses to acrolein and acetic acid vapors are altered breathing patterns and airway obstruction, that sensory nerves play an important role in these responses, and that these responses are enhanced in animals with allergic airway disease.

Does Intercostal Stretch Alter Breathing Pattern and Respiratory Muscle Activity in Conscious Adults?

The effects of intercostal (IC) stretch on breathing patterns and respiratory muscle activity were monitored in nine healthy subjects. Tidal volume (Vt), breathing frequency (Fb), and inspiratory (Ti) and expiratory (Te) durations were determined from a pneumotachometer. Peak amplitudes and burst durations of activity in the diaphragm, parasternal ICs and external abdominal oblique muscles were determined from surface EMGs. The third and eighth IC spaces were stretched in phase with inspiration or expiration when supine and 60° semi recumbent. Vt increased and Ti and Te were prolonged, resulting in a decreased Fb, independent of site of stretch, phase of breathing, or body position, during IC stretch compared to controls. Peak amplitudes and burst durations of diaphragmatic EMG and burst durations of parasternal ICs were greater when the third and eighth IC spaces were stretched during inspiration compared to controls. Peak amplitudes of parasternal ICs increased only when the third IC space was stretched during inspiration. When applied during expiration, IC stretch increased only parasternal activity in the supine position. Intercostal stretch applied in phase with inspiration resulted in a slower, deeper breathing pattern with increased activity of the diaphragm and parasternal IC muscles. IC stretch may alter breathing sufficiently to improve gas exchange in some patients with pulmonary disorders.

Breathing pattern retraining and exercise in persons with chronic obstructive pulmonary disease.

Breathing pattern retaining, in the form of pursed-lip breathing, has been used as one method in pulmonary rehabilitation to help alleviate the symptoms of dyspnea endured by people who suffer from airflow obstruction secondary to chronic obstructive pulmonary disease (COPD). Other techniques such as biofeedback also have been successfully used. This article describes the altered breathing patterns used by patients with COPD at rest and during physical activity. The literature is reviewed regarding techniques of breathing pattern retraining that have been developed to improve the capacity of persons with COPD to perform activities of daily living, a primarily rehabilitative outcome.

Biomechanical changes of the oral and craniofacial regions as a result of altered breathing patterns

The purpose of this report is to discuss the biomechanical changes in the oral and craniofacial regions as a result of altered breathing patterns. The increase in air pollution and allergens, resulting in allergic reactions, is often the cause of chronic nasal obstruction. The biomechanics of the oral, cranial and facial areas are intimately linked, and will be adversely affected by any change in the breathing pattern. As a result of nasal obstruction, the biomechanics of respiration changes to facilitate mouth breathing, and the resting position of the tongue and mandible is disrupted. The lips are parted, the freeway space and craniocervical angulation increase. The muscle activity of the posterior cervical musculature, anterior temporalis and suprahyoid muscles will be increased. The equilibrium of forces in the oral and craniofacial region is disturbed, and these abnormal forces could lead to the development of “adenoid facies”, malocclusions and dysfunction over a period of time. It is important to diagnose chronic nasal obstruction and mouth breathing early and start treatment before the negative effects of the musculoskeletal system occur. A sound understanding of the biomechanical changes will enable the physiotherapist to carry out a skilful examination and plan a treatment program, based on informed decisions.

TIME COURSE OF RESPONSE TO OZONE EXPOSURE IN HEALTHY ADULT FEMALES

Ozone exposure causes acute decrements in pulmonary function, increases airway responsiveness, and changes the breathing pattern. We examined these responses in 19 ozone-responsive (D FEV1 > 5%) young females exposed to both air and 0.35 ppm ozone. The randomized 75-min exposures included two 30-min exercise periods at V E 40 L/min. Responses were measured before, during, and after exposure and at 18 and 42 h postexposure. FVC, FEV1, and FIV0.5 decreased (p < .01) immediately postexposure by 13.2%, 19.9%, and 20.8%, respectively, and the airway responsiveness was significantly increased. Raw increased (p < .05), while TGV remained essentially unchanged. At 18 h postexposure, the airways were still hyperresponsive and FEV1 and FIV0.5 were still 5% below the preexposure levels. There were no residual effects in any of the variables at 42 h postexposure. During exercise in ozone the tidal volume was decreased (-14%) and respiratory frequency increased (+15%). The changes in airway responsiveness were not related to changes in spirometric measurements. We found no significant differences between postair and postozone mouth occlusion pressure (Pm0.1) and the hypercapnic response to CO2 rebreathing. We conclude that ozone induced typical acute changes in airway responsiveness and that ventilatory (exercise), spirometric (inspiratory and expiratory), and plethysmographic pulmonary function may show some residual effects for up to 18 h after exposure. The ozoneinduced alteration in breathing pattern during exercise does not appear to be related to a change in ventilatory drive.

Altered Breathing Pattern and Tachycardia in Young Lambs Exposed To Nicotine Prenatally

Altered Breathing Pattern and Tachycardia in Young Lambs Exposed To Nicotine Prenatally

Influence of drive and timing mechanisms on breathing pattern and ventilation during mental task performance

Assessment of multiple respiratory measures may provide insight into how behavioral demands affect the breathing pattern. This is illustrated by data from a study among 44 subjects, in which tidal volume, respiration rate, minute ventilation and indices of central drive and timing mechanisms were assessed via inductive plethysmography, in addition to end-tidal PCO 2. After a baseline, three conditions of a memory comparison task were presented. The first two conditions differed only with regard to the presence or absence of feedback of performance (NFB and FB). In the third `all-or-nothing' (AON) condition, subjects only received a monetary bonus, if their performance exceeded that of the previous two conditions. Minute ventilation increased from baseline to all task conditions, and from NFB and FB to AON. Respiration rate increased in all task conditions, but there were no differences between task conditions. Tidal volume decreased during NFB, but was equal to baseline during FB and AON. Of the respiratory control indices, inspiratory flow rate covaried much more closely with minute ventilation than duty cycle. The task performance induced a minor degree of hyperventilation. The discussion focusses on how behavioral demands affect respiratory control processes to produce alterations in breathing pattern and ventilation.

The effects of cervical epidural anesthesia with bupivacaine on pulmonary function in conscious patients.

Cervical epidural anesthesia (CEA) can affect diaphragmatic function. We investigated the effects of CEA on the diaphragm muscle performance, breathing pattern, and respiratory drive of 10 healthy patients undergoing hand surgery before and after the administration of 0.25% and 0.375% bupivacaine. The lung volumes and flows, respiratory rate (RR), minute ventilation, respiratory cycle time, occlusion pressure, maximal inspiratory pressure (MIP), and hand grip strength were determined. ETCO2 and SpO2 were continuously monitored. The diaphragmatic excursion was evaluated using ultrasonography. Although CEA allowed painless hand rehabilitation, both 0.25% and 0.375% bupivacaine impaired diaphragmatic excursion, with values decreasing from 5.6 to 4.4 and 3.3 cm (P < 0.05), respectively, during forced sniff maneuvers. In the 0.25% and 0.375% bupivacaine groups, the values of MIP decreased from 74 to 56 and 44 cm H2O, forced vital capacity decreased from 3.8 to 3.2 and 2.8 L, and hand grip strength decreased from 43.3 to 27.8 and 20.5 kg force, respectively (P < 0.05). The tidal volume decreased from 0.8 to 0.6 and 0.5 L in the 0.25% and 0.375% bupivacaine groups, respectively, the RR increased from 14 to 18 breaths/min in both groups, and the occlusion pressure increased from 1.5 to 2.1 and 2.9 cm H2O in the 0.25% and 0.375% bupivacaine groups, respectively (P < 0.05). ETCO2 increased from 35.2 to 38.1 and 39.3 mm Hg in the 0.25% and 0.375% bupivacaine groups, respectively, and SpO2 decreased by 2% +/- 1% in the 0.375% bupivacaine group. CEA affects diaphragmatic function and the resulting lung volumes and MIP values. The observed alterations in breathing pattern and the significant increase in ventilatory drive may be caused by changes in the diaphragmatic muscle tension and an augmented CO2 load. In conclusion, we do not recommend this technique for routine postoperative hand rehabilitation using the studied bupivacaine concentrations. We studied cervical epidural anesthesia in healthy patients undergoing hand surgery. The technique allowed painless rehabilitation but affected breathing pattern, diaphragmatic function, and respiratory drive. We cannot recommend this technique for routine clinical use.

Relationships between Hippocampal Activity and Breathing Patterns

HARPER, R. M., G. R. POE, D. M. RECTOR, M. P. KRISTENSEN. Relationships between hippocampal activity and breathing patterns. NEUROSCI BIOBEHAV REV 22(2) 233–236, 1998.—Single cell discharge, EEG activity, and optical changes accompanying alterations in breathing patterns, as well as the knowledge that respiratory musculature is heavily involved in movement and other behavioral acts, implicate hippocampal regions in some aspects of breathing control. The control is unlikely to reside in oscillatory breathing movements, because such patterns emerge in preparations retaining only the medulla (and perhaps only the spinal cord). However, momentary changes in breathing patterns induced by affect, startle, whole-body movement changes, or compensatory ventilatory changes mediated by rostral brain regions likely depend on hippocampal action in aspects of control. Hippocampal activity was enhanced prior to sighs, and this enhancement was accompanied by increased slow theta activity. Theta frequency increased during apnea, prior to return of breathing. Consideration of hippocampal contributions to breathing control should be viewed in the context that significant interactions exist between blood pressure changes and ventilation, and that modest breathing challenges, such as exposure to hypercapnia or to increased resistive loads, bring into action a vast array of brain regions involving nearly every level of the neuraxis.

Ozone affects breathing and pulmonary surfactant function in mice

The effect on breathing of BALB/c mice immediately following ozone exposure (2 ppm) for 0, 2, 4, 6, and 8 h was studied with a whole body plethysmograph. Whether such exposure affected the normal function of pulmonary surfactant of maintaining airway patency was evaluated with a capillary surfactometer. Respiratory rate in mice that were not exposed was 358±16 (mean±S.E.) breaths/min and decreased to 202±10 after 6 h exposure. The mean pressure change caused by breathing diminished significantly, indicating a reduced tidal volume. BAL fluid from controls maintained patency for 88±2% of the study time, 120 s, implying a good surfactant function, but the ozone exposure caused the surfactant to lose its capability of maintaining patency ( P<0.0001).This decaying surfactant function of the BAL fluid coincided with an increasing protein concentration in the fluid of exposed animals (1.46±0.14 mg/ml in the 8-h group) as compared to controls (0.44±0.04 mg/ml, P<0.0001). It is concluded that leakage of plasma proteins into the airway lumen was probably the main reason for the surfactant dysfunction, which may have contributed to the altered breathing pattern.

Physiologic benefits of exercise training in rehabilitation of patients with severe chronic obstructive pulmonary disease.

We determined the effect on exercise tolerance and physiological exercise responses of rigorous rehabilitative exercise training in chronic obstructive pulmonary disease (COPD). Fifteen men and 10 women (mean age, 68 +/- 6 yr; FEV1, 0.93 +/- 0.27 L) participated in a rehabilitation program with an exercise component of three per week 45-min sessions of cycle ergometer training for 6 wk with exercise intensity kept near maximal targets. Before and after rehabilitation, patients performed an incremental test and a constant work rate (CWR) test at 80% of the peak work rate in the preprogram incremental test. Ventilation (V(E)) and gas exchange were measured breath by breath; arterialized venous blood was analyzed for blood gas determinations and lactate. Rehabilitation yielded an average increase in peak work rate in the incremental test of 36% (p < 0.001), and in the duration of the CWR test of 77% (p < 0.001). In the CWR test, the kinetics of O2 uptake, CO2 output, V(E), and heart rate were markedly slower than those of healthy subjects. After training, mean response time decrease averaged 17, 22, 34, and 29%, respectively (p < 0.02), evidence of a physiologic training effect. Further, for identical CWR tasks, V(E) was 10% lower (p < 0.02) after training, attributable to altered breathing pattern: tidal volume increased by 8% and respiratory rate decreased by 19%, yielding lower V(D) /V(T) (0.46 versus 0.53 p < 0.005). Rigorous exercise training for patients with severe COPD yields more efficient exercise breathing pattern and lower V(E); this is associated with improved exercise tolerance.

Contribution of vagal afferents to breathing pattern in rats with lung fibrosis

In anesthestized male Wistar rats with bleomycin-induced lung fibrosis we examined the influence of lung vagal non-myelinated and myelinated afferents in setting breathing pattern. Fourteen days after intratracheal instillation of bleomycin, lung compliance, total lung capacity (TLC) and inspiratory capacity were reduced while functional residual capacity and residual volume were increased. Baseline tidal volume (V t) was decreased and frequency (f r) increased in the bleomycin treated rats compared with controls. Selective vagal C-fiber blockade did not affect f r or V t in any group. Vagotomy resulted in an increase in V t and decrease in f r in both groups with the percent increase in V t/TLC and decrease in f r being significantly greater in the bleomycin rats compared with controls. Vagotomy also attenuated the significantly elevated P CO 2 in the bleomycin treated rats suggesting that bleomycin-induced alterations in breathing pattern contribute to blood gas abnormalities. We conclude that vagal myelinated afferents contribute to the rapid shallow breathing in bleomycin treated rats.

This Month in the Journal

This Month in the Journal

Effect of apparatus on functional residual capacity

As the route of breathing and use of airway apparatus such as mask, mouthpiece and noseclip can alter breathing pattern, this study has used the helium dilution method to estimate the effects of mouthpiece and mask breathing on functional residual capacity (FRC) in the supine position, and the change in FRC that occurs between the sitting and supine positions while breathing by mouthpiece. In 13 normal subjects, breathing by mouthpiece, FRC was smaller, by a median of 1.07 litre (interquartile values 0.73-1.43 litre) in the supine compared with the sitting position (P < 0.01), but residual volume (RV) did not change significantly. FRC measured in the supine position was significantly greater when breathing by mask than by mouthpiece (0.25, 0.04-0.38 litre) and RV was greater by similar amounts (0.20, -0.02 to 0.49 litre). This difference may result from increased inspiratory activity while breathing via the mask.

Control of breathing patterns and abdominal muscles during graded loads and tilt.

Tilting from supine to upright purportedly enhances both segmental and pulmonary proprioceptive feedback, whereas an expiratory threshold load (ETL) preferentially enhances pulmonary feedback. To test this we studied 13 adults when supine and 60 degrees and 90 degrees head up. We measured tidal volume, inspiratory duration (TI), and expiratory duration (TE) from flow; estimated end-expiratory lung volume from inspiratory capacity; and determined burst amplitudes and durations from abdominal electromyograms (EMGs). ETLs were incremented from 0 (control) to 25 cmH2O in 5-cmH2O steps. Tidal volume was significantly increased by ETL but was unaffected by body position. Every load prolonged TE, whereas TI remained unchanged. When subjects were supine, abdominal EMGs were silent but became tonically active when subjects were upright. During ETL, abdominal activity became rhythmical and phase locked to expiration. Bursts amplitudes were enhanced with each increment in ETL, but burst durations did not change even though TE was prolonged. The altered breathing pattern and active expiration augmented inspiratory flow and decreased end-tidal PCO2. Responses were greatest when subjects were 90 degrees head up. The load-related increments in abdominal recruitment, with no change in burst durations, fit the concept of two central pattern generators: one controlling pattern and the other controlling rhythm of the central respiratory drive.

Carotid chemoreceptors and respiratory adaptations to dead space loading during incremental exercise.

Dead space (VD) loading has been shown to cause an increase in tidal volume and a decrease in respiratory frequency at moderate to high levels of ventilation (VI) during exercise (J. Appl. Physiol. 70: 55-62, 1991). This study examined the role of carotid chemoreceptors (CC) in the breathing pattern response to added VD during maximal incremental exercise; we used hyperoxia to silence the CC. Nine healthy subjects exercised on a bicycle ergometer on 4 different days while inspiring air with VD (AVD) and without VD [air control (AC)] and while inspiring 100% O2 with VD (O2VD) and without VD (O2C). Equipment resistance for VD and control studies was identical, and the exercise tests were done in a randomized order. At a matched level of VI equivalent to 75% VI at the end of the AC experiments (102 l/min), the breathing pattern in the AVD and O2VD tests was significantly deeper and slower (P < 0.05) than that in the AC and O2C tests. The difference in tidal volume between AVD and AC tests (delta = 0.26 +/- 0.16 liter) was not significantly different from that between O2VD and O2C tests (delta = 0.23 +/- 0.23 liter). The breathing pattern was the same in the AC and O2C tests. It is concluded that the altered breathing pattern with VD loading is not mediated by the CC.