Shallow Breathing Pattern Research Articles

Abstract Number ‐ 113: A Lateral Medullary Infarct Complicated by Central Hypoventilation Syndrome

Introduction A 43‐year‐old male with no known past medical history presented to a primary stroke center for sudden onset headache, nausea, vomiting, and dizziness while driving. A computed tomography angiogram of the head and neck revealed a left vertebral artery occlusion, and the patient was transferred to our comprehensive stroke center for further evaluation and treatment. Upon arrival at our facility, the patient was noted to have a national institute of health stroke scale score of 7 with left facial droop, dysarthria, and right upper extremity dysmetria. A cerebral angiogram revealed a tortuous left vertebral artery with dissection in the V4 segment. Subsequent brain diffusion weighted imaging revealed an acute infarct in the right lateral medulla measuring 1.4cm and several acute cerebellar infarcts. (fig. 1) In the postangiography period, the patient had dysphagia, sialorrhea, multiple aspiration episodes, and oral secretions requiring early tracheostomy and percutaneous endoscopic gastrostomy on hospital day (HD) #6. The subsequent hospital course was complicated by prolonged singultus lasting until HD #23 and repetitive vomiting requiring a transition from a gastric to a gastro‐jejunal feeding tube. Methods A central hypoventilation syndrome (CHS) prolonged ventilator weaning. Despite preserved ability to take large‐volume voluntary breaths, the patient experienced multiple episodes of sleep‐associated apnea and rapid shallow breathing pattern during daily spontaneous breathing trials (SBT). The apnea episodes were registered with ventilator apnea alarms set at 20 seconds. This pattern continued when attempting an SBT utilizing a T‐piece adaptor. The ability to maintain adequate minute ventilation in an asleep state subsequently improved, and the patient was able to tolerate 48 hours of spontaneous breathing with no apnea on HD #35. Results Few cases of CHS secondary to lateral medullary infarction (LMI) have been documented in the literature.(1‐3) As the respiratory drive originates from neurons in the latero‐rostro‐ventral medulla, infarcts in this brainstem region may lead to respiratory failure. More specifically to our patient, ataxic breathing may result from lesions in the rostro‐ventral medulla with yawning and hiccups being seen in lesions to the posterolateral medulla.(4) As our patient presented with a sizable 1.4cm lesion, likely impairing these brainstem centers, it is expected that his symptoms would account for multiple respiratory symptoms. The unique feature of the acquired CHS in the setting of LMI is its unilateral location implying lateralization of the respiratory control. In addition to the aforementioned symptoms, his lesion likely led to prolonged weaning from the ventilator as has been described previously.(5) Conclusions This case raises awareness regarding potentially disastrous complications of the lateral medullary syndrome like central hypoventilation syndrome. We urge caution and careful evaluation of patients with lateral medullary infarctions for disorders of the respiratory control system.

Comparing heart rate variability biofeedback and simple paced breathing to inform the design of guided breathing technologies

IntroductionA goal of inbodied interaction is to explore how tools can be designed to provide external interactions that support our internal processes. One process that often suffers from our external interactions with modern computing technology is our breathing. Because of the ergonomics and low-grade-but-frequent stress associated with computer work, many people adopt a short, shallow breathing pattern that is known to have a negative effect on other parts of our physiology. Breathing guides are tools that help people match their breathing patterns to an external (most often visual) cue to practice healthy breathing exercises.However, there are two leading protocols for how breathing cues are offered by breathing guides used in non-clinical settings: simple paced breathing (SPB) and Heart Rate Variability Biofeedback (HRV-b). Although these protocols have separately been demonstrated to be effective, they differ substantially in their complexity and design. Paced breathing is a simpler protocol where a user is asked to match their breathing pattern with a cue paced at a predetermined rate and is simple enough to be completed as a secondary task during other activities. HRV-b, on the other hand, provides adaptive, real-time guidance derived from heart rate variability, a physiological signal that can be sensed through a wearable device. Although the benefits of these two protocols have been well established in clinical contexts, designers of guided breathing technology have little information about whether one is better than the other for non-clinical use.MethodsTo address this important gap in knowledge, we conducted the first comparative study of these two leading protocols in the context of end-user applications. In our N=28 between-subject design, participants were trained in either SPB or HRV-b and then completed a 10-minute session following their training protocol. Breathing rates and heart rate variability scores were recorded and compared between groups.Results and discussionOur findings indicate that the exercises did not significantly differ in their immediate outcomes – both resulted in significantly slower breathing rates than their baseline and both provided similar relative increases in HRV. Therefore, there were no observed differences in the acute physiological effects when using either SPB or HRV-b. Our paper contributes new findings suggesting that simple paced breathing – a straightforward, intuitive, and easy-to-design breathing exercise – provides the same immediate benefits as HRV-b, but without its added design complexities.

Experienced Respiratory Symptoms and the Impact on Daily Life from the Perspective of People with Parkinson's Disease: A Grounded Theory.

Background:Abnormal respiratory function tests can be observed early in the course of Parkinson’s disease (PD). A better understanding of the impact of respiratory dysfunction on daily life in PD is needed to prevent later occurring complications as a (aspiration) pneumonia.Objective:To explain which respiratory symptoms people with PD or a form of atypical parkinsonism experience and how these symptoms impact on their daily lives.Methods:This qualitative study used a grounded theory approach. A purposeful sample strategy was used to capture information-rich cases. Data were collected in semi-structured interviews with participants diagnosed with either PD (n = 11) or atypical parkinsonism (n = 3), all of whom had confirmed respiratory symptoms. Data were analyzed using grounded theory analysis by creating codes, categories, theoretical themes, and, ultimately, a conceptual model.Results:Four respiratory profiles emerged, describing different types of respiratory dysfunction, with various positive and negative influencing factors. First, a loss of breathing automatism was experienced. Second, episodes of breathlessness or a rapid, shallow breathing pattern were triggered by either physical exertion, fatigue, or postural deformities. Third, stress and anxiety also triggered episodes of breathlessness. Fourth, a decreased cough strength and frequent coughing. Based on these findings, we constructed a conceptual model that visualizes the relations between these four types of respiratory dysfunction and their impact on daily life, with ‘discomfort’ and ‘avoidance of social activities’ as crucial elements.Conclusion:A tailored approach for each profile of respiratory dysfunction is recommended to improve respiratory dysfunction and to reduce its social impact in people with PD.

Cardiopulmonary Exercise Testing in Patients With Interstitial Lung Disease.

Interstitial lung disease (ILD) is a heterogeneous group of conditions characterized by fibrosis and/or inflammation of the lung parenchyma. The pathogenesis of ILD consistently results in exertional dyspnea and exercise intolerance. Cardiopulmonary exercise testing (CPET) provides important information concerning the pathophysiology of ILD that can help inform patient management. Despite the purported benefits of CPET, its clinical utility in ILD is not well defined; however, there is a growing body of evidence that provides insight into the potential value of CPET in ILD. Characteristic responses to CPET in patients with ILD include exercise-induced arterial hypoxemia, an exaggerated ventilatory response, a rapid and shallow breathing pattern, critically low inspiratory reserve volume, and elevated sensations of dyspnea and leg discomfort. CPET is used in ILD to determine cause(s) of symptoms such as exertional dyspnea, evaluate functional capacity, inform exercise prescription, and determine the effects of pharmacological and non-pharmacological interventions on exercise capacity and exertional symptoms. However, preliminary evidence suggests that CPET in ILD may also provide valuable prognostic information and can be used to ascertain the degree of exercise-induced pulmonary hypertension. Despite these recent advances, additional research is required to confirm the utility of CPET in patients with ILD. This brief review outlines the clinical utility of CPET in patients with ILD. Typical patterns of response are described and practical issues concerning CPET interpretation in ILD are addressed. Additionally, important unanswered questions relating to the clinical utility of CPET in the assessment, prognostication, and management of patients with ILD are identified.

Disordered Leptin signaling in the retrotrapezoid nucleus is associated with the impaired hypercapnic ventilatory response in obesity

Sleep-disordered breathing is characterized by disruptions of normal breathing patterns during sleep. Obesity is closely related to hypoventilation or apnea and becomes a primary risk factor for sleep-disordered breathing. Leptin, a peptide secreted by adipose tissue, has been implicated in central control of breathing. Activation of the retrotrapezoid nucleus (RTN) neurons, a critical central respiratory chemoreceptor candidate, potentiates a central drive to breathing. Here, we ask whether the disordered leptin signaling in the RTN is responsible for obesity-related hypoventilation. In a diet induced obesity (DIO) mouse model, the hypercapnic ventilatory response (HCVR) was assessed and the cellular leptin signaling in the RTN was examined. Our main findings demonstrate that DIO mice exhibit overweight, hypercapnia, high levels of serum and cerebrospinal leptin. During exposure to room air, DIO mice manifest basal hypoventilation with a rapid and shallow breathing pattern. Exposure to CO2 elicits the impaired HCVR in DIO mice. In addition, both the number of CO2-activated neurons and expression of TASK-2 channels in the RTN are dramatically reduced in DIO mice. Moreover, there is leptin signaling disorder in RTN neurons in DIO mice, including a significant decrease in leptin-activated RTN neurons, downregulation of phosphorylated STAT3 and upregulation of SOCS3. Altogether, we suggest that the disordered leptin/STAT3/SOCS3 signaling pathway in the RTN plays a role in obesity-related hypoventilation.

Impact of Dyspnea on Functional Capacity in Breast Cancer Patients

Background and Objective: Breast cancer in females stands most common cancer in India with rate of incidence as 25.8 per 1,00,000 females. In breast and lung cancer dyspnea is more commonly seen. Dyspnea is a multidimensional experience of breathing discomfort.[1] Dyspnea is fourth most common symptom seen in cancer patients.[6] On functional activity breast cancer with dyspnea patients had general respiratory weakness, lower peak exercise capacity and peak ventilation and more shallow and rapid breathing pattern in response to activity. The purpose of this study was to find the impact of dyspnea on functional capacity in breast cancer patients. Material and Methodology: In this cross sectional study,100 subjects were taken between the age of 30-65 years, subjects were taken according to MRC score. Thus tests such as 6MWT and 1MSTS were performed and cancer dyspnea scale was used to determine the impact. Result: A total of 100 patients with dyspnea data were included. The study duration was of 6 months One minute sit to stand test results (n=100, p=0.005),6 minute walk test results (n=100, p=0.005), the main result was showed (n=100, p=0.0001) that was 43% subjects score positive and 57% subjects score negative impact on functional capacity. Conclusion: By this study, it is concluded that there is very low negative impact of dsypnea on functional capacity in breast cancer patients.

Modulation of the tongue muscle activity in response to bronchopulmonary C‐fiber activation following mid‐cervical contused in the rat

The present study was designed to investigate the tongue muscle activity in response to bronchopulmonary C‐fiber activation following mid‐cervical spinal contusion in the rat. The esophageal pressure and electromyogram of extrinsic tongue muscles (genioglossus and hyoglossus) were monitored before and after inhalation of capsaicin (25 and 100 μg/ml) at the acute, subchronic and chronic injured stages after mid‐cervical contusion. The results demonstrated that pre‐inspiratory and inspiratory burst amplitude of tongue muscle were generally enhanced at the acute and subchronic injured stages in mid‐cervical contused animals vs. uninjured animals. Inhalation of capsaicin usually caused a rapid shallow breathing pattern associated with a reduction in pre‐inspiratory and inspiratory activity of the tongue muscle in uninjured animals at the acute injured stage; however, this altered breathing pattern and decreased tongue muscle activity were blunted in contused animals. During the chronic injured stage, the expiratory duration was prolonged to a similar degree in both uninjured and contused animals after inhalation of capsaicin. Notably, inhibition of genioglossus muscle activity during capsaicin inhalation is more severed in chronically contused animals. These results demonstrated that cervical spinal cord injury is associated with alteration of supraspinal respiratory activity, which may modulate upper airway motor outputs and bronchopulmonary C‐fiber mediated respiratory reflexes. The compensatory increase in the tongue muscle activity at the acute injured stage may be benefit to the maintenance of the upper airway patency; however, the susceptible tongue muscle activity during bronchopulmonary C‐fiber activation may increase the risk of airway obstruction during the chronic injured stage.Support or Funding InformationMOST (105‐2628‐B‐110‐002‐MY3 & 108‐2636‐B‐110‐001), Higher Education Sprout Project (07C030111), NSYSU‐KMU Joint Research Project (107‐I001)

Novel peritoneopericardial diaphragmatic hernia in a dog

A 23-month-old German shepherd dog (GSD) with chronic intermittent gastrointestinal signs presented following acute deterioration compatible with gastrointestinal obstruction and suspected peritoneopericardial diaphragmatic hernia (PPDH). Physical examination revealed depression, abdominal...

Using Cine-Averaged CT With the Shallow Breathing Pattern to Reduce Respiration-Induced Artifacts for Thoracic Cavity PET/CT Scans.

OBJECTIVE. PET/CT provides a fusion of both anatomic and functional information. However, because of the temporal difference of both modalities and respiratory motion of lungs, misregistration of lesions is frequently observed on thoracic PET/CT scans. The effect of cine-averaged CT (CACT) acquisition incorporated with the shallow breathing pattern of patients on the improvement of registration and quantification of lesions was investigated. MATERIALS AND METHODS. Thirty patients with cancer who underwent routine PET/CT followed by CACT of the thoracic region were enrolled. The misalignment between PET/helical CT (HCT) and PET/CACT was calculated. In addition, the PET data were attenuation-corrected by HCT and CACT images, and the maximum standardized uptake value (SUVmax) was evaluated. RESULTS. All lesions in the PET/HCT images showed misalignment larger than 5 mm, whereas only 33% of lesions in the PET/CACT images showed misalignment larger than 5 mm. The mean values of the maximum misalignment of the lesions in PET/HCT and PET/CACT images were 14.10 ± 6.26 mm and 5.92 ± 4.31 mm, respectively. Seven percent of the lesions had an increase in SUVmax of more than 20%, and 47% showed a slight increase in SUVmax of less than 5% after applying CACT. The mean percentage difference between the SUVmax of CACT and that of HCT was 12%. CONCLUSION. Using the CACT technique and the shallow breathing pattern effectively reduces misregistration of lesions and recovers the underestimated SUVmax. The CACT method can be applied in clinical practice of thoracic PET/CT for better cancer management.

Ventilatory responses in males and females during graded exercise with and without thoracic load carriage.

To compare the effects of thoracic load carriage on the ventilatory and perceptual responses to graded exercise, 14 pairs of height-matched, physically active males and females completed randomly ordered modified Balke treadmill exercise tests with and without a correctly sized and fitted 20.4kg backpack and work clothing. Subjects walked at 1.56m.s- 1 while grade was increased by 2% every 2min until exhaustion. Ventilatory responses were measured with open circuit spirometry and perceptual responses were evaluated using the modified Borg scale. Inspiratory capacity maneuvers were performed to calculate operating lung volumes. Despite height matching, males had significantly greater lung volumes and peak oxygen uptake ([Formula: see text]O2peak). Peak [Formula: see text]O2 and ventilation ([Formula: see text]E) were lower (p < 0.05) for all subjects under load. Throughout exercise, the ventilatory equivalents for [Formula: see text]O2 and carbon dioxide production were significantly higher in females, independent of condition. At similar relative submaximal intensities (%[Formula: see text]O2peak), there was no difference in [Formula: see text]E between conditions in either group, however, all subjects adopted a rapid and shallow breathing pattern under load with decreased tidal volume secondary to lower end-inspiratory lung volume. The relative changes in breathing pattern and operating lung volume between unloaded and loaded conditions were similar between males and females. Females reported significantly higher dyspnea ratings for a given [Formula: see text]E compared to males; however, the relationship between dyspnea and [Formula: see text]E was unaffected by load carriage. The relative response patterns for ventilatory and perceptual responses to graded exercise with thoracic loading were similar in males and females.

Device Measured Rapid Shallow Breathing Index Reflects Changing Respiratory Patterns but Minute Ventilation Reflects Changing Activity During Worsening Heart Failure in Ambulatory Patients

Background Respiratory distress is common in heart failure (HF) and a primary driver for HF hospitalizations. Minute Ventilation (MV), a product of respiratory rate and tidal volume, is known to be elevated in HF patients due to ventilation/perfusion (V/Q) mismatch. However, it is not known if changes in MV accurately reflect emergence of rapid shallow breathing patterns in ambulatory patients preceding a HF event. Methods The MultiSENSE trial enrolled 900 patients implanted with a COGNIS CRT-D and followed them up to 1 year. Device software was modified to permit collection of chronic diagnostic sensor data including impedance based respiration rate (RR) and tidal volume (TV), which was used to compute MV (= RR*TV) and Rapid Shallow Breathing Index (RSBI = RR/TV), and activity (XL). Daily averages were separately computed over entire 24 hours as well as during resting epochs. HF events (HFEs) were independently adjudicated and defined as HF admissions or unscheduled visits with intravenous HF treatment. Relative changes preceding HFEs were computed between a baseline 30–60 days prior to HFEs (BL) and 3-day pre-HFE (ST) as (ST-BL)/BLx100% and reported as mean +/- SEM. Significance was tested using Wilcoxon signed-rank test. Results 900 patients followed for a year experienced 192 HFEs. Using 24-hour averages, significant changes were observed in RR, TV and RSBI indicating the emergence of rapid shallow breathing pattern leading up to HFE. MV average over 24 hours showed nonsignificant decrease coincident with decreased patient activity but showed no change when daily averaging was limited to resting epochs. In contrast, RR, TV and RSBI were significantly changed even at rest in directions consistent with the emergence of rapid shallow breathing pattern. Conclusion Device measured rapid shallow breathing is significantly elevated in the three day epoch preceding HFEs, whereas minute ventilation is not, in both 24-hour as well as resting period daily averages. Automatic ambulatory longitudinal monitoring of changes in rapid shallow breathing patterns may enable better monitoring for emerging respiratory distress in HF patients.

Characteristic plethysmographic findings in a guinea pig model of COPD

ABSTRACTAim of the Study: Long-term exposure to cigarette smoke generates chronic obstructive pulmonary disease (COPD) in guinea pigs, but a comprehensive evaluation of changes in lung function, as assessed by barometric whole body plethysmography (WBP), is lacking. Materials and Methods: Female guinea pigs were exposed to the smoke of 20 cigarettes/day, 5 days/week, during 10 weeks (COPD group, n = 8), and were compared with unexposed female guinea pigs of the same age (control group, n = 8). WBP was performed in both groups, followed by lung histology. Results: At the end of the exposure period, guinea pigs in the COPD group had higher respiratory frequency, while duty cycle (Ti/Ttot) was unaffected. There was a trend toward minute ventilation (MV) and expiratory flow at the mid-tidal volume (EF50) to be higher in the COPD group. Enhanced pause (Penh) was lower, while time of braking (TB) and time to PEF relative to Te (Rpef) were higher in the COPD group. All guinea pigs exposed to tobacco smoke developed emphysematous lesions in their lungs and gained less body weight than controls. Conclusions: In this COPD model, exposure to cigarette smoke produced changes in WBP characterized by a shallow breathing pattern with decreased Penh and a trend toward increasing EF50 (probably due to decreased elastic recoil), increased TB (suggesting dynamic laryngeal narrowing), and a trend of increasing MV (probably due to a higher metabolic rate). Many of these functional changes resemble those observed in patients with COPD and corroborate the suitability of this guinea pig model for the study of COPD.

Changes of Respiratory Mechanics in COPD Patients from Stable State to Acute Exacerbations with Respiratory Failure

ABSTRACTSymptoms, clinical course, functional and biological data during an exacerbation of chronic obstructive pulmonary disease (EXCOPD) have been investigated, but data on physiological changes of respiratory mechanics during a severe exacerbation with respiratory acidosis requiring noninvasive mechanical ventilation (NIMV) are scant. The aim of this study was to evaluate changes of respiratory mechanics in COPD patients comparing data observed during EXCOPD with those observed during stable state in the recovery phase. In 18 COPD patients having severe EXCOPD requiring NIMV for global respiratory failure, we measured respiratory mechanics during both EXCOPD (T0) and once the patients achieved a stable state (T1). The diaphragm and inspiratory muscles effort was significantly increased under relapse, as well as the pressure-time product of the diaphragm and the inspiratory muscle (PTPdi and PTPes). The resistive loads to breathe (i.e., PEEPi,dyn, compliance and inspiratory resistances) were also markedly increased, while the maximal pressures generated by the diaphragm and the inspiratory muscles, together with forced expired volumes were decreased. All these indices statistically improved but with a great intrasubject variability in stable condition. Moreover, tension-time index (TTdi) significantly improved from the EXCOPD state to the condition of clinical stability (0.156 ± 0.04 at T0 vs. 0.082 ± 0.02 at T1 p < 0.001). During an EXCOPD, the load/capacity of the respiratory pump is impaired, and although the patients exhibit a rapid shallow breathing pattern, this does not necessarily correlate with a TTdi ≥ 0.15. These changes are reverted once they recover from the EXCOPD, despite a large variability between patients.

Diaphragm abnormalities in heart failure and aging: mechanisms and integration of cardiovascular and respiratory pathophysiology.

Inspiratory function is essential for alveolar ventilation and expulsive behaviors that promote airway clearance (e.g., coughing and sneezing). Current evidence demonstrates that inspiratory dysfunction occurs during healthy aging and is accentuated by chronic heart failure (CHF). This inspiratory dysfunction contributes to key aspects of CHF and aging cardiovascular and pulmonary pathophysiology including: (1) impaired airway clearance and predisposition to pneumonia; (2) inability to sustain ventilation during physical activity; (3) shallow breathing pattern that limits alveolar ventilation and gas exchange; and (4) sympathetic activation that causes cardiac arrhythmias and tissue vasoconstriction. The diaphragm is the primary inspiratory muscle; hence, its neuromuscular integrity is a main determinant of the adequacy of inspiratory function. Mechanistic work within animal and cellular models has revealed specific factors that may be responsible for diaphragm neuromuscular abnormalities in CHF and aging. These include phrenic nerve and neuromuscular junction alterations as well as intrinsic myocyte abnormalities, such as changes in the quantity and quality of contractile proteins, accelerated fiber atrophy, and shifts in fiber type distribution. CHF, aging, or CHF in the presence of aging disturbs the dynamics of circulating factors (e.g., cytokines and angiotensin II) and cell signaling involving sphingolipids, reactive oxygen species, and proteolytic pathways, thus leading to the previously listed abnormalities. Exercise-based rehabilitation combined with pharmacological therapies targeting the pathways reviewed herein hold promise to treat diaphragm abnormalities and inspiratory muscle dysfunction in CHF and aging.

Sex differences in the intensity and qualitative dimensions of exertional dyspnea in physically active young adults.

Understanding sex differences in the qualitative dimensions of exertional dyspnea may provide insight into why women are more affected by this symptom than men. This study explored the evolution of the qualitative dimensions of dyspnea in 70 healthy, young, physically active adults (35 M and 35 F). Participants rated the intensity of their breathing discomfort (Borg 0-10 scale) and selected phrases that best described their breathing from a standardized list (work/effort, unsatisfied inspiration, and unsatisfied expiration) throughout each stage of a symptom-limited incremental-cycle exercise test. Following exercise, participants selected phrases that described their breathing at maximal exercise from a list of 15 standardized phrases. Intensity of breathing discomfort was significantly higher in women for a given ventilation, but differences disappeared when ventilation was expressed as a percentage of maximum voluntary ventilation. The dominant qualitative descriptor in both sexes throughout exercise was increased work/effort of breathing. At peak exercise, women were significantly more likely to select the following phrases: "my breathing feels shallow," "I cannot get enough air in," "I cannot take a deep breath in," and "my breath does not go in all the way." Women adopted a more rapid and shallow breathing pattern and had significantly higher end-inspiratory lung volumes relative to total lung capacity throughout exercise relative to men. These findings suggest that men and women do not differ in their perceived quality of dyspnea during submaximal exercise, but subjective differences appear at maximal exercise and may be related, at least in part, to underlying sex differences in breathing patterns and operating lung volumes during exercise.

Ventilatory responses to prolonged exercise with heavy load carriage.

The purpose of this experiment was to study breathing pattern and operating lung volume during 45 min of exercise with a heavy backpack (25 kg) and examine the effect of this exercise on respiratory muscle strength. Fifteen males completed randomly ordered graded exercise tests on a treadmill with and without a correctly sized and fitted 25 kg pack. Subsequently, each subject completed, in random order, on separate days, 45 min of treadmill walking with and without the pack. Oxygen demand was matched between conditions (loaded: 3.01 ± 0.11 and unloaded 3.02 ± 0.11 L min(-1)). With load, breathing frequency (f B) and minute ventilation increased by 21.7 and 15.1 % (P < 0.05), respectively, while tidal volume (V T) and end-inspiratory lung volume (EILV) were reduced by 6.3 and 6.4% (P < 0.05), respectively, compared to unloaded. Following loaded exercise, maximal inspiratory pressure decreased by 6.7% (P < 0.05) with no change in maximal expiratory pressure. No changes in maximal inspiratory or expiratory pressures were observed following unloaded exercise. Despite equivalent oxygen demand, perceived exercise stress and breathing discomfort was higher (P < 0.05) in the loaded condition. The mechanical disadvantage placed on the respiratory system during exercise with a heavy pack led to compensatory changes in breathing pattern and EILV, and a reduction in maximal inspiratory pressure post-exercise. We suggest that in an attempt to minimize the work of breathing, subjects adopted a shallow and frequent breathing pattern. However, this pattern increased deadspace and minute ventilation, which likely contributed to altered perceptions of exercise stress and breathing discomfort.

Changes in lung function testing associated with obesity

Excess bodyweight has an important impact on the physiology of breathing. In fact, it affects resting lung volumes and exercise capacity. These effects appear as a consequence of ventilatory and inflammatory changes commonly associated to obesity. As a result, obese individuals have a rapid and shallow pattern of breathing, their respiratory compliance is reduced and the airway resistance tends to be higher. However, with respect to aerobic capacity, contradictory results have been reported depending on the way peak oxygen uptake is expressed. Moreover, the inability of this population to achieve maximal efforts during exercise testing also affects their cardiorespiratory fitness.

Respiratory motor outputs following unilateral midcervical spinal cord injury in the adult rat

The present study was designed to investigate the impact of midcervical spinal cord injury on respiratory outputs and compare respiratory recovery following high- vs. midcervical spinal injury. A unilateral hemisection (Hx) in the spinal cord at C2 or C4 was performed in adult rats. Respiratory behaviors of unanesthetized animals were measured at normoxic baseline and hypercapnia by whole body plethysmography at 1 day and 1, 2, 4, and 8 wk after spinal injury. C2Hx and C4Hx induced a similar rapid shallow breathing pattern at 1 day postinjury. The respiratory frequency of C4Hx animals gradually returned to normal, but the tidal volume from 1 to 8 wk postinjury remained lower than that of the control animals. Linear regression analyses indicated that the tidal volume recovery was greater in the C4Hx animals than in the C2Hx animals at the baseline, but not at hypercapnia. The bilateral phrenic nerve activity was recorded in anesthetized animals under different respiratory drives at 8-9 wk postinjury. The phrenic burst amplitude ipsilateral to the lesion reduced following both high- and midcervical Hx; however, the ability to increase activity was lower in the C4Hx animals than in the C2Hx animals. When the data were normalized by the maximal inspiratory effort during asphyxia, the phrenic burst amplitude enhanced in the C4Hx animals, but reduced in the C2Hx animals compared with the control animals. These results suggest that respiratory deficits are evident following midcervical Hx, and that respiratory recovery and neuroplasticity of phrenic outputs are different following high- vs. midcervical spinal injury.

Asbestos-related pleural plaques

An 85-year-old man with type 2 diabetes mellitus presented to our clinic with the chief complaints of dry cough and dyspnea on exertion for several months. The oxygen saturation under ambient room air was 92%. Upon physical examination, the patient looked ill and appeared with rapid, shallow breathing pattern. Fine, end-inspiratory crackles were auscultated at bilateral basal lungs. Chest radiography (Figure 1a) and computed tomography (CT) (Figure 1b) showed calcified pleural plaques, mostly distributed along …

Schwann cell transplantation enhances diaphragm recovery following cervical spinal cord injury

Respiratory function is compromised following cervical spinal cord injuries (cSCI) due to interruption of respiratory pathways. Peripheral nerve grafts, a source of Schwann cells (SCs), alone or in combination with other treatments have been reported to promote improved respiration after cervical hemisection. SC transplantation in a contusion model has shown to improve locomotor function. In this study, we looked at how SCs would affect respiration in a clinically‐relevant contusion cSCI model.Adult female rats received lateralized C3/C4 contusion cSCI, leading to a rapid shallow breathing pattern (RSB). At 1 week post‐injury, animals were injected into the lesion site with SCs (~2.5 million) expressing either mCherry or green fluorescent protein (gfp). Controls were lesioned only. Animals receiving SCs were immunosuppressed. Respiratory function under eupneic and hypercapnic conditions was assessed. Histological analyses confirmed survival of SCs. Our initial findings show that RSB was absent in SC recipients, which also had improvement in diaphragm EMG activity during hypercapnia. Preliminary results with grafts of SCs expressing Chondroitinase ABC did not have any additional effect. These preliminary results suggest SCs can alone promote recovery after experimental cSCI. Identifying substrates mediating this recovery and how brainstem plasticity is affected also are under investigation.