Prolonged Expiration Research Articles

Clinical diagnosis of pneumonia, typical of experts

Clinical diagnosis of pneumonia is a concern when a patient presents with recent cough--new or worsened--together with fever as the chief complaint. Given this presentation, the doctor would benefit from having access to software that specifies, first, what diagnostic indicators experts typically use in that diagnosis; then, upon entry of those facts, what experts' typical probability of pneumonia is in such a case; and finally, how much this probability might change upon adding the facts from chest radiography. We specified a set of 36 hypothetical presentations of this type by patients 20-70 years of age, involving a comprehensive set of clinical-diagnostic indicators. Members of three separate expert panels independently set the probability of pneumonia in each of these cases, and also the range of possible post-radiography probabilities. A logistic function of the diagnostic indicators was fitted to the medians of the probabilities. The median probability of pneumonia was a joint function of the patient's age and current rate of cigarette smoking; history as to the cough's duration, the fever's maximum, dyspnea (including whether on effort only) and rigors; and physical examination as to temperature, signs of upper respiratory infection, prolongation of expiration, dullness on percussion and some auscultation findings. Non-contributory were history of wheezing, pain on inspiration, type of sputum and signs of cold or influenza. This probability function, and the post-radiography functions based on the same indicators, are accessible at http://www.evimed.ch/pneumonia. The expert inputs to clinical diagnosis that were derived and made readily accessible provide for expertly clinical diagnosis of pneumonia, relevant for decisions about radiography and treatment without it.

INTERNAL JUGULAR VEIN VALVE INSUFFICIENCY IN COUGH SYNCOPE

A 53-year-old man with chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea was admitted to the hospital for the evaluation of recurrent syncopal episodes induced by paroxysmal cough. Loss of consciousness was brief, and preceded by the sensation of “fullness in the head.” Syncope was provoked also by prolonged expiration during spirometry, which revealed severe bronchial obstruction. However, oxygen saturation on room air and blood gases were within normal limits. To reproduce reported symptoms, the Valsalva maneuver (VM) was performed with the patient in the supine position with noninvasive, continuous blood pressure monitoring (Finapres, Ohmeda) and finger pulse oximetry. This resulted in a brief loss of consciousness, although no desaturation, decrease in blood pressure, or bradycardia was noted. Transthoracic echocardiography revealed normal left and right ventricular function, mild tricuspid insufficiency, and no evidence of pulmonary hypertension. There was no right-to-left shunt detected on the bubble-contrast study. Neurologic assessment, MRI of the brain, and EEG were unremarkable. Duplex-Doppler examination of extracranial carotid and vertebral arteries showed no stenosis. However, evaluation of the internal jugular veins (IJVs) with the use of color Doppler revealed right internal jugular valve insufficiency with flow reversal during inspiration (figure …

Catathrenia (Nocturnal Groaning): What is It?

Catathrenia (Nocturnal Groaning): What is It?

Catathrenia (nocturnal groaning): an abnormal respiratory pattern during sleep

Catathrenia (nocturnal groaning) is a rare condition characterized by monotonous irregular groans occurring during sleep. Ten patients (five women; mean age: 27 +/- 7.4 years, range: 15-41) with sleep-related groaning persisting for years or decades and normal daytime fibreoptic laryngoscopy and respiratory function tests underwent videopolysomnographic recording (VPSG) analysing their respiratory patterns during sleep. After the VPSG, all patients were clinically followed up for a mean period of 4.9 +/- 3.5 years. On VPSG, all patients showed nocturnal groaning during NREM sleep and particularly during REM sleep stages. Groaning was associated with disproportionate prolonged expiration causing reduced breathing rate without oxygen desaturation. The breathing pattern with prolonged expiration and sound production alternated with a normal respiratory pattern without groaning. Endoesophageal pressure during groaning showed mildly positive swings at the initial phase of expiration suggesting a partial mild expiratory upper airway obstruction. At the end of the follow-up period, all patients reported persistent nocturnal groaning but no other clinical manifestations. Groaning confined to sleep alternating with normal breathing and the absence of long-term clinical consequences suggest that catathrenia is because of an abnormality of the internal respiratory drive system, possibly related to persistence of a neonatal (vestigial) type of breathing pattern.

Delayed bezafibrate‐induced angio‐oedema in a 68‐year‐old man

Delayed bezafibrate‐induced angio‐oedema in a 68‐year‐old man

Exercise Challenge Test in 3- to 6-Year-Old Asthmatic Children

The exercise challenge test (ECT) is a common tool to assess exercise-induced asthma (EIA) in school-aged children. EIA has not been explored in the early childhood setting. To assess the existence of EIA in children in this age group. A 6-min, controlled, free-run test was performed in 55 children (age range, 3 to 6 years old) who were classified into the following groups: 30 children in whom asthma had been previously diagnosed (group A); and 25 children with prolonged coughing (group B). Spirometry measurements were obtained before the run, and at 1, 2, 3, 5, 10, and 20 min after the run. A positive finding of EIA was defined as a 13% decrease from baseline FEV(1) or baseline forced expiratory volume in the first 0.5 s (FEV(0.5)). The actual duration of each run was age-related (mean [+/- SD] duration, 4.8 +/- 0.8 min). The nadir in indexes occurred after a mean time of 2.98 +/- 1.31 min. A positive EIA finding determined by FEV(1) was present in 15 children, and by FEV(0.5) in 34 children. Twenty-six children were from group A, but only 8 children were from group B. Wheezing and/or prolonged expiration were associated with a positive test result in 31 of 34 children. Coughing was frequent in children with both negative and positive ECT findings. The present study documents for the first time the presence of EIA in response to a free-run test in early childhood. Our findings suggest that a free-run test for the presence of EIA is suitable, but that the running duration is limited by age. The duration of airflow limitation after exercise is significantly earlier and shorter in young children with asthma compared with older children. FEV(0.5) is a better index than the traditional FEV(1) for describing positive ECT results in young children. The association of wheezing and/or prolonged expiration may help in defining EIA in early childhood in the absence of a spirometer.

Prolonged expiration down to residual volume leads to severe arterial hypoxemia in athletes during submaximal exercise

The goal of this study was to assess the effects of a prolonged expiration (PE) carried out down to the residual volume (RV) during a submaximal exercise and consider whether it would be worth including this respiratory technique in a training programme to evaluate its effects on performance. Ten male triathletes performed a 5-min exercise at 70% of maximal oxygen consumption in normal breathing (NB(70)) and in PE (PE(70)) down to RV. Cardiorespiratory parameters were measured continuously and an arterialized blood sampling at the earlobe was performed in the last 15s of exercise. Oxygen consumption, cardiac frequency, end-tidal and arterial carbon dioxide pressure, alveolar-arterial difference for O(2) (PA(O2) - Pa(O2)) and P(50) were significantly higher, and arterial oxygen saturation (87.4+/-3.4% versus 95.0+/-0.9%, p<0.001), alveolar (PA(O2)) or arterial oxygen pressure, pH and ventilatory equivalent were significantly lower in PE(70) than NB(70). There was no difference in blood lactate between exercise modalities. These results demonstrate that during submaximal exercise, a prolonged expiration down to RV can lead to a severe hypoxemia caused by a PA(O2) decrement (r=0.56; p<0.05), a widened PA(O2) - Pa(O2) (r=-0.85; p<0.001) and a right shift of the oxygen dissociation curve (r=-0.73; p<0.001).

Effect of inspired oxygen fraction on alveolar derecruitment in acute respiratory distress syndrome

High fractions of inspired oxygen (FIO(2)) used in acute lung injury (ALI) may promote resorption atelectasis. The impact of derecruitment related to high FIO(2) in ALI is debated. We evaluated derecruitment with 100% vs. 60% FIO(2) at two levels of positive end-expiratory pressure (PEEP). Fourteen consecutive patients with ALI were studied. Recruited volume at two PEEP levels was computed from two pressure-volume curves, recorded from PEEP and from zero end-expiratory pressure, using the sinusoidal flow modulation method. PEEP-induced recruitment was measured during prolonged expiration as the difference between the two curves at a given pressure. PaO(2)/FIO(2) was also measured. PEEP was 5 +/- 1 or 14 +/- 3 cmH(2)O and FIO(2) was 60% or 100%, yielding four combinations. We looked for differences between the beginning and end of a 30-min period with each combination. With low PEEP and 100% FIO(2), recruited volume decreased significantly from 68 +/- 53 to 39 +/- 43 ml and PaO(2)/FIO(2) from 196 +/- 104 to 153 +/- 83 mmHg. With the three other combinations (low PEEP and 60% FIO(2) or high PEEP and 60% or 100% FIO(2)) none of the parameters decreased significantly. In mechanically ventilated patients with ALI the breathing of pure oxygen leads to derecruitment, which is prevented by high PEEP.

Optimally fitted tracheal tubes decrease the probability of postextubation adverse events in children undergoing general anesthesia

The air leak test is recommended for assessing the appropriate size of an uncuffed tracheal tube (TT) in children. Our objectives were to determine whether there is a certain threshold air leak value beyond which a higher risk for adverse events after removal of TT can be predicted and to define other risk factors related to extubation. We enrolled 234 cases ranging from newborn to 9 years of age requiring tracheal intubation for elective or emergency surgery. General anesthesia was induced by a mask or intravenously. The TT size was calculated using the formula: [age (years)/4] + 4.5. After the induction of anesthesia, the patient's trachea was intubated and the correct position was confirmed. The attending anesthetist assessed the leak pressure. Incidences of adverse events (prolonged or barking cough, obstructed or prolonged inspiration or expiration, subcostal and sternal retractions, arterial desaturation, or laryngospasm) were recorded after removal of TT. Ten patients were excluded from the study. A total of 218 children underwent 224 operations under general anesthesia. Children who had an absent air leak at 25 cmH(2)O pressure had 2.8 times more adverse events during emergence from anesthesia than those with an audible air leak. Adverse events after the removal of TT were 3.7 times more likely to occur in children whose anesthesia was provided by a less experienced anesthesia trainee. Adverse events after removal of TT were more likely to occur in children with an absent air leak at 25 cmH(2)O pressure and in children whose anesthesia was provided by a less experienced anesthetist.

Decreased barosensitivity in rats conditioned with intermittent hypoxia

Decreased barosensitivity has been identified as a contributing factor in hypertension. Conditioning rats with chronic (30 d) intermittent hypoxia (CIH) leads to hypertension. Indeed, early reports indicate that barosensitivity may be decreased in CIH-conditioned animals. We tested this hypothesis directly in adult male Sprague Dawley (Zivic Miller) rats by recording splanchnic sympathetic nerve (sSNA) and phrenic nerve activities (PNA) and their changes to step increases in blood pressure (BP). Intermittent hypoxia consisted of 15 s with ambient oxygen below 6% interspersed with 5 min of room air for 8 h each day. Mean arterial blood pressure was increased approximately 5, 10 and 20 mmHg by inflating an embolectomy catheter (#2 Fr) that was inserted in the descending aorta above the renal arteries. Data analysis compared the breathing pattern and respiratory cycle-triggered averages of sSNA before, during and after each stimulus. Increases in BP coincidently decreased sSNA and respiratory rate, i.e., prolonged expiration without amplitude effects. Further, the elicited decrease in sSNA recorded in naïve animals (n=2) appeared greater than that of conditioned animals (n=3). These preliminary results indicate that decreased barosensitivity coupled with increased chemosensitivity promote increased sSNA associated with the hypertension in CIH conditioned animals. Supported by NIH/NHLBI 25830

Modulation of the Hering-Breuer reflex by raphe pallidus in rabbits

Activation of the pulmonary stretch receptors by lung inflation or vagal stimulation evokes Hering-Breuer (HB) reflex, which is characterized by inspiratory inhibition and expiratory prolongation. In this work, whether the HB reflex could be modulated by the serotonergic raphe pallidus (RP) was studied by comparing the strength of this reflex before and after electrical or chemical stimulation of the RP. Experiments were performed on urethane anesthetized adult rabbits. The HB reflex was simulated with electrical stimulation of the central end of cervical vagus nerve. The RP was stimulated electrically or chemically by microinjection of glutamate. We found that after either electrical stimulation or chemical stimulation of the RP, the inspiratory inhibition and expiratory prolongation of the HB reflex were significantly attenuated. This attenuation showed post-stimulation time dependency or short-term memory, as well as RP stimulation intensity dependency. Results of the present study suggested that the serotonergic RP could exert its respiratory effects by modulating the strength of HB reflex.

Oral Feeding in the Preterm Infant

After completing this article, readers should be able to: 1. Describe the sequential development of sucking, swallowing, and respiration. 2. Delineate the limitation of an infant’s oral feeding skills at specific times of development to provide realistic expectations for oral feeding performance. 3. Define oral feeding success in preterm infants. 4. Use the current knowledge of preterm infants’ oral motor skills to facilitate and enhance their performance. 5. Enumerate the potential short- and long-term consequences of an infant’s oral feeding aversion for the patient, family, and health professional. Oral feeding issues in preterm infants are a growing concern for neonatologists because attainment of independent oral feeding is one of the prerequisites for hospital discharge. With the increase in survival of infants born continuously more preterm, understanding such issues has a certain urgency. Concerns do not pertain only to difficulties encountered by neonatologists during the birthstay hospitalization, but also by pediatricians and pediatric gastroenterologists who attend to long-term feeding difficulties/disorders, such as oral feeding aversion. Indeed, greater than 40% of patients followed in feeding disorder clinics are former preterm infants. Research over the last decade has begun to shed light on the development of oral feeding skills in these infants as they mature, which has increased understanding of their limited skills at varying postmenstrual ages. Such knowledge is crucial in clinical practice insofar as expectations of these infants’ oral feeding performance must take into account the ever-changing level of maturity of their skills. This article focuses on the development of sucking, swallowing, and respiration (as it pertains to oral feeding) and the coordination of these three functions. Additional factors, separate from infant feeding skills, also are discussed because they can affect oral feeding performance. This review examines information gathered from bottle feeding because more extensive research has been conducted on bottle feeding than on breastfeeding. However, …

Chronic hypoxia abolishes expiratory prolongation following carotid sinus nerve stimulation in the anesthetized rat

In anesthetized rats, increases in phrenic nerve (PN) amplitude and frequency during brief periods of hypoxia or electrical stimulation of the carotid sinus nerve (CSN) are followed by an increase in expiratory duration. We investigated the effects of chronic exposure to hypoxia on PN responses to CSN stimulation. In Inactin anesthetized (100 mg/kg) Sprague-Dawley rats PN discharge and arterial pressure responses to 10-120 s of CSN stimulation (20 Hz, 0.2 ms duration pulses) were recorded after 7-10 days exposure to hypoxia (10 +/- .5% O2). In normoxic rats, the degree of CSN-evoked expiratory prolongation was dependent upon the duration of CSN stimulation. CSN-evoked increases in PN burst amplitude were not different comparing chronic hypoxic rats to rats maintained at normoxia while CSN-evoked increases in PN burst frequency were greater in chronic hypoxic rats (p<.05). CSN-evoked expiratory prolongation was abolished in chronic hypoxic rats. Following chronic hypoxia, changes occur within the central processing of arterial chemoreceptor inputs so that CSN stimulation evokes an enhanced PN frequency response and no expiratory prolongation.

A Pox on Your House

A 31-year-old, previously healthy white man presented to the emergency department with complaints of malaise, fevers, shortness of breath, a non-productive cough, and a "rash." His physical exam revealed a temperature of 100.2F, a pulse of 129 bpm, respiratory rate of 14 BPM, and blood pressure of 140/74 mm Hg. He was alert, oriented, and in no distress. His oropharynx was dry, his neck was supple, and cervical lymphadenopathy was absent. He had tachycardia, bilateral wheezes, and rhonchi with prolonged expirations. There was a diffuse vesicular eruption enveloping his entire body with involvement sparing his palms and soles (Figures 1 and 2). Laboratory values showed a hemoglobin of 16.0 g/dL and a white blood cell count of 7100 cells/pL, with 39%neutrophils, 23% bands, and 35% lymphocytes. His platelet count was mildly decreased to 86,000 x 103/pL. Chest radiograph revealed bilateral diffuse interstitial infiltrates. A diagnosis of acute varicella-zoster virus pneumonia (varicella pneumonia) was made, and the patient was started on IV acyclovir (10 mg/kg every 8 hours). Upon further questioning, the patient stated that his daughter had been diagnosed with "chickenpox" 7 days ago. The patient had numerous exposures to chickenpox in the past but had never developed clinical expressions of varicella. He was not at risk for HIV infection, not having multiple sexual partners, IV drug abuse, or blood transfusions. During the 1 day of in-hospitalization, his fever abated and the pulmonary signs diminished. Following discharge, IV acyclovir was replaced by valacyclovir to complete a 7-day course of therapy.

Histamine induced airway response in pre-school children assessed by a non-invasive EMG technique

The aim of the study was to investigate the association between surface electromyographic (EMG) activity of the diaphragm and intercostal muscles, and clinical symptoms (wheeze, cough, increased respiratory rate and prolonged expiration) during bronchial challenge testing and after administration of salbutamol in asthmatic pre-school children. A histamine challenge test was performed in 20 asthmatic pre-school children. The histamine dose at the appearance of 1 or more clinical symptoms was defined as the maximum histamine provocation dose (PDcs). The clinical symptoms were recorded with a microphone over the trachea. The logarithm of the EMG-Activity-Ratio (log EMGAR; mean peak activity ratio to baseline of respiratory muscles during tidal breathing) was used as EMG parameter. In both the diaphragmatic and the intercostal log EMGAR values a linear increase was observed in the four histamine dose-steps prior to PDcs. At PDcs the mean log EMGAR of the diaphragm (di) and intercostal muscles (int) was significantly increased as compared to the baseline values. After administration of salbutamol the log EMGARdi and log EMGARint returned to baseline values and the clinical symptoms normalized in all children. At PDcs, no significant differences in the log EMGAR values could be detected at the appearance of the distinctive clinical symptoms, which suggests that wheezing is not the only indicator for the detection of airway responsiveness in young children. We found a linear association between histamine dose and the increase in surface diaphragmatic and intercostal respiratory EMG activity during a bronchial challenge test in pre-school asthmatic children, which returned to baseline values after inhalation of salbutamol. These findings support the idea that EMG measurements of the diaphragm and intercostal muscles may offer an opportunity to estimate airway response in young children in an alternative way.

Revised one-step method for determination of cardiac output.

Cardiac output (Q) is a determinant of blood pressure and O(2) delivery and is critical in the maintenance of homeostasis, particularly during environmental stress and exercise. Cardiac output can be determined invasively in patients; however, indirect methods are required for other situations. Soluble gas techniques are widely used to determine (Q). Historically, measurements during a breathhold, prolonged expiration and rebreathing to CO(2) equilibrium have been used; however, with limitations, especially during stress. Farhi and co-workers developed a single-step CO(2) rebreathing method, which was subsequently revised by his group, and has been shown to be reliable and compared closely to direct, invasive measures. V(CO2), P(ACO2), and P(VCO2) are determined during a 12-25s rebreathing, using the appropriate tidal volume, and (Q) is calculated. This method can provide accurate data in laboratory and field experiments during exercise, increased or decreased gravity, water immersion, lower body pressure, head-down tilt, altered ambient pressure or changes in inspired gas composition.

Infection‐induced wheezing during the first year of life does not mean asthma: a 50‐year‐old observation

Boesen published in Acta Paediatrica 50 y ago before the era of laboratory studies for respiratory viruses or for markers of atopy an article considering the outcome of young children with wheezing. In the years 1940-1945 185 infants or young children were admitted to hospital with asthmatic bronchitis defined by the presence of prolonged expiration in a child with respiratory tract infection. By currently used diagnostic terms the material of the study consisted of patients with bronchiolitis and obstructive (or wheezy) bronchitis. In 1951 when the children were 6-11 y of age a questionnaire was sent to all of them and 162 (88%) answered. Thirty-one of them were = 5 mo 54 were 6-11 mo 44 were 1-2 y and 33 were = 3 y of age during the original hospitalization. There were four main results in the study. (excerpt)

Cardiac output: a view from Buffalo.

Cardiac output (Q) is a primary determinant of blood pressure and O2 delivery and is critical in the maintenance of homeostasis, particularly during environmental stress. Cardiac output can be determined invasively in patients; however, indirect methods are required for other situations. Soluble gas techniques are widely used to determine Q. Historically, measurements during a breathhold, prolonged expiration and rebreathing to CO2 equilibrium have been used; however, with limitations, especially during stress. Farhi and co-workers developed a single-step CO2 rebreathing method, which was subsequently revised by his group, and has been shown to be valid (compared to direct measures) and reliable. Carbon dioxide output (VCO2), partial pressure of arterial CO2 (PaCO2), and partial pressure of mixed venous CO2 (Pv(CO2)) are determined during 12-25 s of rebreathing, using the appropriate tidal volume, and Q is calculated. This method has the utility to provide accurate data in laboratory and field experiments during exercise, increased and micro-gravity, water immersion, lower body pressure, head-down tilt, and changes in gas composition and pressure. Utilizing the Buffalo CO2 rebreathing method it has been shown that the Q can adjust to a wide range of changes in environments maintaining blood pressure and O2 delivery at rest and during exercise.

The issue of dynamic hyperinflation in acute respiratory distress syndrome patients.

Dynamic hyperinflation is produced by a diffuse expiratory flow limitation impairing exhalation under mechanical ventilation. It constitutes a serious clinical problem in patients exhibiting bronchial asthma or chronic obstructive pulmonary disease, when mechanical ventilation is required. But this phenomenon may also complicate respiratory support in acute respiratory distress syndrome (ARDS) patients. The presence of diffuse airflow limitation in ARDS patients has sometimes been noticed in the past, but its consequences have only recently been emphasised in a dynamic study, using bedside recording of flow/volume loops during respiratory support. More recently, by recording systematically a prolonged expiration, the current authors have observed a localised airflow limitation in a majority of ARDS patients, constituting another potential factor of dynamic hyperinflation under respiratory support. In the same report, the current authors' have emphasised the impact of this limitation on the shape of the pressure/volume loop. At a time when increasing respiratory support is proposed to improve carbon dioxide clearance in acute respiratory distress syndrome submitted to protective ventilation, dynamic hyperinflation may become a major clinical problem in this setting.

Interrater Agreement in the Clinical Evaluation of Acute Pediatric Asthma

Prior studies of observer agreement of the clinical exam of children with asthma have focused on small numbers of specially trained observers, often in the setting of clinical trials. Our objective was to evaluate interobserver reliability in the physical exam of acute pediatric wheezing and asthma among a large group of diverse examiners, in a setting of routine clinical practice, and without prior special training. The setting was a large urban children's hospital. Observers were attending pediatric emergency physicians and fellows; hospital respiratory therapists; and emergency department (ED) nurses. Patients were children receiving nebulized medications for wheezing in the ED or inpatient asthma unit. Pairs of observers simultaneously but independently rated work of breathing, wheeze, decreased air entry, prolonged expiration, breathlessness, respiratory rate, mental status, and global (or overall) severity using a structured exam template. A total score for each exam was also evaluated. A total of 230 pairs of observations were performed; mean patient age was 5.3 years. For all pairs, the weighted kappa statistics for the exam components ranged from 0.61 to 0.74 (moderate or substantial agreement). The global severity category and total score had weighted kappas of 0.80 and 0.82, respectively (excellent agreement). Agreement was generally somewhat lower for unlike (different profession) observer pairs than for like observer pairs, but remained acceptable. Agreement in two age groups (≤3 years old and ≥4) was at least moderate for all exam components analyzed. Spearman rank correlations between individual exam components and the global assessments of patient severity were all greater than 0.5, indicating at least moderate to good correlations. We found substantial interobserver agreement among a broad range of examiners in the components of the clinical examination of acute wheezing in both younger and older children. This is contrary to the commonly held observation that the poor interobserver reliability of physical exam findings in asthma may limit their usefulness as asthma outcome measures. Support for use of a structured respiratory exam format or template in asthma guidelines was also shown.