Increase In Respiratory Effort Research Articles

Effect of Ambulatory Oxygen on the Respiratory Pattern during the 6 Min Walking Test in Patients with Interstitial Lung Diseases.

Patients with pulmonary fibrosis experience early oxyhemoglobin desaturation under effort, which limits their ability to exercise and their quality of life. Recent studies have shown that in resting normoxaemic patients who become hypoxemic under exertion, administration of outpatient oxygen significantly improves stress dyspnoea and quality of life. It is unclear how this happens, since oxygen administration does not act directly on dyspnoea, and does not appear to have much effect on the heart rate and pulmonary artery pressure. We tested the hypothesis that correcting the hypoxaemia could reduce the increase in respiratory effort during the 6 min walking test, recording the breathing pattern during administration of oxygen or placebo. We evaluated 20 patients with fibrotic interstitial lung diseases (17 males and 3 females; mean age 72 ± 2 years; M ± SE) with a resting SpO2 ≥92 that fell to ≤88% during the 6 min walk test (6MWT). After first establishing the oxygen flow necessary to prevent desaturation, the patients underwent two further 6MWT, 15-20 min apart, one with administration of medical air and one with oxygen at the same flow, in randomized double-blind order. During the test, SpO2, heart rate, respiratory rate, tidal volume and minute ventilation (VE) were recorded, using a Spiropalm spirometer (Cosmed, Rome, Italy). Oxygen saturation during the 6MWT decreased to a minimum value of 82.3% (95% CI 80.1-84.5%) during placebo and to 92% (90.3-93.7%) during oxygen with an average difference of 9.7% (7.8-11.6%, p < 0.0001). On the contrary, heart rate showed an increasing trend with walking time reaching a significantly higher maximum rate during placebo, with a difference of 5.4 bpm (2.9-8.7, p < 0.005) compared to oxygen. The distance walked was slightly but significantly greater after oxygen by 28 m (2-53, p < 0.05) and end of test dyspnoea after placebo by 0.6 points (0.1-1.1, p < 0.05). Respiratory rate increased over time, without differences between oxygen and placebo in the first minute of walking, then increasing significantly more during placebo (p < 0.0005). With placebo, tidal volume increased rapidly reaching a plateau at about 48% of FVC after 3 min, while with oxygen, the increase was slower, reaching a maximum of about 45% of FVC at the end of the test. Nevertheless, the difference was highly significant (p < 0.0005) at all the time points. Minute ventilation also increased significantly with walking time but remained at a highly significant lower level during oxygen than placebo at all the time points. Mean reduction in VE during the test with oxygen compared to placebo was 4.4 L/min (3.9-4.9, p < 0.0005). In our ILD patients, administration of outpatient oxygen during walking was related to a reduced increase in heart rate, respiratory rate, tidal volume and minute ventilation necessary to meet increased oxygen requirements, resulting in a lower workload on the cardiovascular system and on respiratory muscles and a consequent reduction in dyspnoea.

Flow-Identified Site of Collapse During Drug-Induced Sleep Endoscopy: Feasibility and Preliminary Results

Flow-Identified Site of Collapse During Drug-Induced Sleep Endoscopy: Feasibility and Preliminary Results

Carbon dioxide narcosis due to human error in a dog

Incorrect assembly of a parallel Lack (Mapleson A) breathing system resulted in carbon dioxide narcosis in a dog due to rebreathing of expiratory gases. A seven-year-old, male neutered Rottweiler, weighing 49 kg, failed to recover after discontinuation of inhalational anaesthesia following a forequarter amputation for osteosarcoma. During recovery, the endotracheal tube had been connected to a parallel Lack anaesthetic breathing system delivering 100 per cent oxygen at 5 l/minute. Although a prolonged recovery, 30 minutes, all vital parameters were considered within normal limits until a severe increase in respiratory effort was noted. Capnography revealed rebreathing with an end-tidal carbon dioxide tension of &gt;150 mm Hg (&gt;19.9 kPa). The dog was transferred to a circle breathing system, and with normalisation of the capnogram, recovery proceeded without further complications. Visual inspection of the parallel Lack breathing system revealed misassembly which had resulted in rebreathing of expiratory gases, extreme hypercapnia causing prolonged recovery due to narcosis.

Emergency typhlectomy for caecal strangulation caused by chronic diaphragmatic hernia in a dog

A two‐year‐old female entire Catahoula leopard dog was referred for investigation and management of suspected chronic diaphragmatic hernia, 11 months post road traffic accident. The dog had a two‐month history of progressive lethargy and one‐week history of vomiting and anorexia. Physical examination revealed a slight increase in respiratory effort with normal respiratory rate. Cardiac and pulmonary sounds were muffled on thoracic auscultation and intestinal loops were not immediately palpable in the abdomen. Thoracic radiographs acquired before referral were suggestive of a diaphragmatic hernia, which was later confirmed on abdominal and thoracic ultrasound. Cardiorespiratory deterioration was evident eight hours post presentation and an emergency exploratory laparotomy was performed. The small intestines, caecum, and the ascending and transverse colon were found to have herniated into the thorax. Marked caecal necrosis was found intraoperatively. A typhlectomy and repair of the diaphragmatic defect were performed. The patient recovered uneventfully and was in good health nine months postoperatively.

Neurobehavioral Outcomes in School-Aged Children with Primary Snoring.

We assess behavioral and attentional problems and neurocognitive functioning in school-aged children with primary snoring (PS). Seventeen children with PS and 27 non-snoring peers aged 6-10years took part in the study. All children underwent a polysomnography (PSG) at the Sleep Laboratory. Snoring was defined by parents and with PSG. Children with obstructive sleep apnea were excluded. The parents completed the Sleep Disturbance Scale for Children. Parents and teachers assessed behavioral and attentional problems with the Child Behavior Checklist and the Conners' Rating Scale-Revised. Neuropsychological assessment included the Wechsler Intelligence Scale for Children and the Developmental Neuropsychological Assessment (NEPSY test). The PS group had significantly more parent-reported internalizing, total, and attentional problems than the control group. Teachers did not report behavioral problems in the PS group. The PS and control groups had equal IQ scores and similar core neurocognitive functions, except for one visuospatial subtest. The PS group had significantly more inspiratory flow limitation and increased diaphragmatic electromyography compared with the controls. Parents reported significantly more daytime sleepiness in the PS group. Daytime sleepiness and snoring time were consistently associated with more behavioral and attentional problems. Flow limitation and more oxygen saturation values under 90% were associated with attentional problems, higher oxygen desaturation index, and lower mean oxygen saturation percentage with reduced language functions. Snoring with an increase in respiratory effort without apneas and hypopneas and parent-reported daytime sleepiness may be linked to daytime symptoms. School-aged children with PS are at risk for behavioral and attentional problems, but not cognitive impairments.

Repetitive versus standard tactile stimulation of preterm infants at birth – A randomized controlled trial

AimTo evaluate the direct effect of repetitive tactile stimulation on breathing effort of preterm infants at birth. MethodsThis randomized controlled trial compared the effect of repetitive stimulation on respiratory effort during the first 4 min after birth with standard stimulation based on clinical indication in preterm infants with a gestational age of 27–32 weeks. All details of the stimulation performed were noted. The main study parameter measured was respiratory minute volume, other study parameters assessed measures of respiratory effort; tidal volumes, rate of rise to maximum tidal volumes, percentage of recruitment breaths, and oxygenation of the infant. ResultsThere was no significant difference in respiratory minute volume in the repetitive stimulation group when compared to the standard group. Oxygen saturation was significantly higher (87.6 ± 3.3% vs 81.7 ± 8.7%, p = .01) while the amount of FiO2 given during transport to the NICU was lower (28.2 (22.8–35.0)% vs 33.6 (29.4–44.1)%, p = .04). There was no significant difference in administration of positive pressure ventilation (52% vs 78%, p = .13), or the duration of ventilation (median (IQR) time 8 (0–118)s vs 35 (13–131)s, p = .23). Caregivers decided less often to administer caffeine in the delivery room to stimulate breathing in the repetitive stimulation group (10% vs 39%, p = .036). ConclusionAlthough the increase in respiratory effort during repetitive stimulation did not reach significance, oxygenation significantly improved with a lower level of FiO2 at transport to the NICU. Repetitive tactile stimulation could be of added value to improve breathing effort at birth.

Impact of arousal threshold and respiratory effort on the duration of breathing events across sleep stage and time of night

PurposeThe frequency and duration of breathing events are influenced by sleep stage and time of day. In the present study we examined if these modifications are linked to adaptations in the arousal threshold and/or the magnitude of respiratory effort during and immediately after breathing events. MethodsParticipants with sleep apnea slept for 3h in the evening and morning. For breathing events detected during these sessions the rate of change of respiratory effort, maximum respiratory effort immediately prior to termination of an event, and the maximum tidal volume and the minimum partial pressure of end-tidal carbon dioxide (PETCO2) immediately following an event were measured. ResultsThe rate of change of respiratory effort was similar in N2 compared to N1 but the maximum respiratory effort immediately prior to event termination was greater (−10.7±1.2 vs. −9.6±1.0cmH2O/s, P<0.05). Likewise, tidal volume was increased (1169±105 vs. 1082±100ml, P<0.05) and PETCO2 was decreased (37.0±0.8 vs. 37.7±0.8mmHg P<0.05) following events in N2 compared to N1. A similar tidal volume and PETCO2 response was evident following events in the morning compared to the evening independent of sleep stage. ConclusionsWe conclude that alterations in the arousal threshold, reflected by an increase in respiratory effort at event termination, coupled to increases in tidal volume and reductions in PETCO2 contribute to modifications in event duration and frequency associated with variations in sleep state or time of night.

Inspiratory flow limitation in a normal population of adults in São Paulo, Brazil.

Inspiratory flow limitation (IFL) during sleep occurs when airflow remains constant despite an increase in respiratory effort. This respiratory event has been recognized as an important parameter for identifying sleep breathing disorders. The purpose of this study was to investigate how much IFL normal individuals can present during sleep. Cross-sectional study derived from a general population sample. A "normal" asymptomatic sample derived from the epidemiological cohort of São Paulo. This study was derived from a general population study involving questionnaires and nocturnal polysomnography of 1,042 individuals. A subgroup defined as a nonsymptomatic healthy group was used as the normal group. N/A. All participants answered several questionnaires and underwent full nocturnal polysomnography. IFL was manually scored, and the percentage of IFL of total sleep time was considered for final analysis. The distribution of the percentage of IFL was analyzed, and associated factors (age, sex, and body mass index) were calculated. There were 95% of normal individuals who exhibited IFL during less than 30% of the total sleep time. Body mass index was positively associated with IFL. Inspiratory flow limitation can be observed in the polysomnography of normal individuals, with an influence of body weight on percentage of inspiratory flow limitation. However, only 5% of asymptomatic individuals will have more than 30% of total sleep time with inspiratory flow limitation. This suggests that only levels of inspiratory flow limitation > 30% be considered in the process of diagnosing obstructive sleep apnea in the absence of an apnea-hypopnea index > 5 and that < 30% of inspiratory flow limitation may be a normal finding in many patients.

Pulse transit time as a measure of respiratory effort under noninvasive ventilation

Among the respiratory events that may occur during nocturnal noninvasive ventilation (NIV), differentiating between central and obstructive events requires appropriate indicators of respiratory effort. The aim of the present study was to assess pulse transit time (PTT) as an indicator of respiratory effort under NIV in comparison with oesophageal pressure (P(oes)). During wakefulness, PTT was compared to P(oes) during spontaneous breathing and under NIV with or without induced leaks in 11 healthy individuals. In addition, the contribution of PTT versus P(oes) to differentiation of central from obstructive respiratory events occurring under NIV during sleep was evaluated in 10 patients with obesity hypoventilation syndrome (OHS). From spontaneous breathing to NIV without leaks, respiratory effort decreased significantly whereas, with increasing level of leaks, there was a significant increase in respiratory effort. Changes in PTT accurately reflected changes in P(oes). In OHS patients during nocturnal NIV, intraclass correlation coefficients between P(oes) and PTT were 0.970 for total number of events and 0.970 for percentage of central events. PTT accurately reflects the unloading of respiratory muscles induced by NIV and the increase in respiratory effort during leaks. PTT during sleep is also useful to differentiate central from obstructive respiratory events occurring under NIV.

Novel methods to diagnose obstructive sleep apnea in children

Sleep-disordered breathing encompasses a spectrum of disorders that increase in severity from snoring to obstructive sleep apnea (OSA). OSA is a clinical disorder that requires a polysomnogram (PSG) to make the diagnosis. The PSG is the gold standard to confirm OSA. Alternative diagnostic tests are presented to supplement the clinical evaluation with objective information when evaluating the snoring child. Diagnostic tests to identify the anatomical site of obstruction are also discussed.

Critérios diagnósticos e tratamento dos distúrbios respiratórios do sono: RERA

In polysomnography, RERA is defined as a respiratory parameter that indicates an arousal associated with a respiratory event and an increase in respiratory effort. Initially, RERA was described by means of esophageal manometry for the evaluation of respiratory effort. This greater respiratory effort occurs as a response to an increase in upper airway resistance, which is a factor present in the pathophysiology of sleep-disordered breathing, such as obstructive sleep apnea syndrome and upper airway resistance syndrome. Later, the use of a nasal pressure cannula was reported to be a reliable means of identifying airflow limitation and one that is more sensitive than is a thermistor. In addition, the nasal pressure cannula method has been used as a surrogate for esophageal manometry in the identification of periods in which upper airway resistance increases. Consequently, the American Academy of Sleep Medicine recommend the use of either method for the identification of RERA, which is defined by the flattening of the inspiratory curve, characteristic of airflow limitation. Although RERA has been identified and evaluated in current medical practice, it has yet to be standardized. Therefore, it is recommended that polysomnographic reports indicate which abnormal respiratory events were taken into consideration in the evaluation of the severity of sleep-disordered breathing.

Disseminated, histologically confirmed Cryptococcus spp infection in a domestic ferret

A 4-year-old castrated male domestic ferret from central Massachusetts was evaluated for weight loss over a 1.5-month period and for 2 days of retching, diarrhea, and signs of lethargy. It had been housed indoors, with 2 other ferrets, 2 cats, and humans that lacked signs or symptoms of disease. Physical examination revealed a thin body condition, tachypnea, an increase in respiratory effort, and retching. Splenomegaly was detected during abdominal palpation. Clinicopathologic analysis revealed lymphopenia, lactic acidosis, hypoglycemia, hypocalcemia, hypoalbuminemia, and hyperglobulinemia. A pulmonary bronchointerstitial pattern was evident on radiographs, and abdominal ultrasonography revealed a suspected pancreatic mass and mesenteric lymphadenopathy. After 2 weeks of medical treatment and once clinical signs resolved, an exploratory laparotomy was performed and a lymph node biopsy specimen was collected. Histologic evaluation of the specimen revealed Cryptococcus-like organisms. Antifungal treatment was initiated with itraconazole (PO) and amphotericin B (IV). The ferret died after 2 days of treatment. A full necropsy was performed, revealing multicentric cryptococcosis affecting the lungs, brain, spleen, and multiple lymph nodes. Paraffin-embedded, formalin-fixed lung tissue was submitted for DNA extraction, and the organism was identified as Cryptococcus neoformans var grubii. To the authors' knowledge, this is the first report of disseminated cryptococcosis in a North American ferret. This case is unique in that the ferret lived indoors, in a geographic region in which reports of cryptococcosis are rare. The genotyping technique used to identify the Cryptococcus strain can aid in better understanding the epidemiology of cryptococcosis.

Chronic fatigue, unrefreshing sleep and nocturnal polysomnography

Background and purpose To investigate the complaint of unrefreshing sleep with study of sleep electroencephalogram (EEG) in patients with chronic fatigue. Patients and methods Fourteen successively seen patients (mean age: 41.1 9.8) who complained of chronic fatigue but denied sleepiness and agreed to participate were compared to 14 controls (33.6±10.2 years) who were monitored during sleep recorded in parallel. After performing conventional sleep scoring we applied Fast Fourier Transformation (FFT) for the delta 1, delta 2, theta, alpha, sigma 1, sigma 2, beta EEG frequency bands. The presence of non-rapid eye movement (NREM) sleep instability was studied with calculation of cyclic alternating pattern (CAP) rate. Two-way analysis of variance (ANOVA) was performed to analyze FFT results and Mann–Whitney U-test to compare CAP rate in both groups of subjects. Results Slow wave sleep (SWS) percentage and sleep efficiency were lower, but there was a significant increase in delta 1 (slow delta) relative power in the chronic fatigue group when compared to normals ( P<0.01). All the other frequency bands were proportionally and significantly decreased compared to controls. CAP rate was also significantly greater in subjects with chronic fatigue than in normals ( P=0.04). An increase in respiratory effort and nasal flow limitation were noted with chronic fatigue. Conclusions The complaints of chronic fatigue and unrefreshing sleep were associated with an abnormal CAP rate, with increase in slow delta power spectrum, affirming the presence of an abnormal sleep progression and NREM sleep instability. These specific patterns were related to subtle, undiagnosed sleep-disordered breathing.

Effects of Prehospital Spinal Immobilization: A Systematic Review of Randomized Trials on Healthy Subjects

To evaluate the effects of spinal immobilization on healthy participants. A systematic review of randomized, controlled trials of spinal immobilization on healthy participants. Seventeen randomized, controlled trials compared different types of immobilization devices, including collars, backboards, splints, and body strapping. For immobilization efficacy, collars, spine boards, vacuum splints, and abdominal/torso strapping provided a significant reduction in spinal movement. Adverse effects of spinal immobilization included a significant increase in respiratory effort, skin ischemia, pain, and discomfort. Data from this review provide the best available evidence to support the well-recognized efficacy and potential adverse effects of spinal immobilization. However, comparisons of different immobilization strategies on trauma victims must be considered in order to establish an evidence base for this practice.

Effects of reduced rebreathing time, in spontaneously breathing patients, on respiratory effort and accuracy in cardiac output measurement when using a partial carbon dioxide rebreathing technique: a prospective observational study

IntroductionNew technology using partial carbon dioxide rebreathing has been developed to measure cardiac output. Because rebreathing increases respiratory effort, we investigated whether a newly developed system with 35 s rebreathing causes a lesser increase in respiratory effort under partial ventilatory support than does the conventional system with 50 s rebreathing. We also investigated whether the shorter rebreathing period affects the accuracy of cardiac output measurement.MethodOnce a total of 13 consecutive post-cardiac-surgery patients had recovered spontaneous breathing under pressure support ventilation, we applied a partial carbon dioxide rebreathing technique with rebreathing of 35 s and 50 s in a random order. We measured minute ventilation, and arterial and mixed venous carbon dioxide tension at the end of the normal breathing period and at the end of the rebreathing periods. We then measured cardiac output using the partial carbon dioxide rebreathing technique with the two rebreathing periods and using thermodilution.ResultsWith both rebreathing systems, minute ventilation increased during rebreathing, as did arterial and mixed venous carbon dioxide tensions. The increases in minute ventilation and arterial carbon dioxide tension were less with 35 s rebreathing than with 50 s rebreathing. The cardiac output measures with both systems correlated acceptably with values obtained with thermodilution.ConclusionWhen patients breathe spontaneously the partial carbon dioxide rebreathing technique increases minute ventilation and arterial carbon dioxide tension, but the effect is less with a shorter rebreathing period. The 35 s rebreathing period yielded cardiac output measurements similar in accuracy to those with 50 s rebreathing.

Endorphins and the control of breathing. Ability of naloxone to restore flow-resistive load compensation in chronic obstructive pulmonary disease.

Since narcotic drugs profoundly depress breathing, we tested whether endogenous opioids influenced control of breathing in chronic obstructive pulmonary disease (COPD), reasoning that the stress of chronic dyspnea might cause elaboration of "endorphins." In 14 patients with COPD (but without respiratory failure) and eight normal controls, we measured ventilation, mechanical lung function, respiratory sensitivity to carbon dioxide, and the increase in respiratory effort elicited by an increase in resistance to breathing; each measurement was performed before and after administration of the opiate antagonist naloxone. Before naloxone, increased resistance to breathing enhanced respiratory effort in all controls, but seven of 14 patients with COPD had no response. After naloxone, these seven patients had load responses. Furthermore, the respiratory effort elicited by the resistance also increased after the drug was given to the patients who had had a response. These data suggest that endorphin elaboration minimizes the stress of chronic airway obstruction.