Functional approach to infants and young children with noisy breathing: validation of pneumotachography by blinded comparison with bronchoscopy

Flow-volume loop evaluation yields considerable diagnostic information about adult patients with upper airway obstruction. No conclusive data support the reliability of this method in young children with noisy breathing. We used analysis of flow-volume loops at tidal breathing (TB-FV) as a first diagnostic approach to young children presenting with persistent noisy breathing (chronic stridor and/or wheezing). Flexible fiberoptic bronchoscopy was performed to establish a conclusive diagnosis and was used to verify the accuracy of the preliminary functional localization of the airway obstruction causing noisy breathing. The physician conducting pneumotachography was blinded to the bronchoscopic findings in the study, and the investigators conducting bronchoscopy were blinded to the pneumotachographic findings. Through a 6-yr period, 113 consecutive young children (ranging in age from 15 to 48 mo) with noisy breathing were enrolled in the study. Three morphologically abnormal TB-FV patterns, as compared with the normal round-shaped TB-FV loops obtained with 15 healthy children, were identified in 110 patients. A TB-FV pattern of inspiratory fluttering was found in 26 subjects and in the first 3 yr of the study was always associated with an endoscopic diagnosis of isolated laryngomalacia. Subsequently, this pattern was used to diagnose isolated laryngomalacia in 18 other infants, in whom endoscopy was avoided. Of infants with endoscopic evidence of airway obstruction ranging from the glottis to the mainstem bronchi (49 subjects), all but three showed a TB-FV loop pattern characterized by expiratory-limb flattening. A concave expiratory loop, with early expiratory peak flow and low flow at low volume, was invariably associated with peripheral bronchoconstriction, without endoscopic evidence of anatomic abnormalities (20 cases). In conclusion, TB- FV loop analysis is a noninvasive, accurate method of establishing the site of airway obstruction in young children with recurrent stridor and/or wheezing. Clinical use of this method may provide interesting pathophysiologic information and may be useful in addressing the diagnostic management of such children.     

Functional upper airway obstruction. Psychogenic pharyngeal constriction.

A 15-year-old boy, known to have asthma, developed acute inspiratory airway obstruction with marked stridor. Spirometry indicated extrathoracic airway obstruction and a bronchofiberoptic examination disclosed narrowing in the hypopharynx. After administration of sedatives, the stridor suddenly disappeared. Psychotherapy decreased the frequency of subsequent stridor attacks. It is suggested that psychogenic pharyngeal constriction may have caused the upper airway obstruction with respiratory distress.     

Brief upper airway (laryngeal) dysfunction

We describe in six men, recurrent episodes recurring over months or years, of sudden, brief complete obstruction to respiration followed by dyspnoea with loud inspiratory stridor lasting two to five minutes. Attacks occurred during wakefulness and/or sleep. In one patient an episode was witnessed endoscopically: the initial obstruction was seen to be caused by complete laryngeal closure. The false vocal cords then opened, but the vocal cords remained adducted and caused inspiratory stridor. The similarity of the attacks described by the other patients suggests that they were all caused by laryngeal closure. Furthermore, they could simulate the episodes by voluntarily adducting their vocal cords. The symptoms were usually preceded by a sensation of throat irritation and in four cases symptoms of upper respiratory infection were present. Associated features present in some of the patients included post-nasal discharge, snoring, sleep apnoea and gastro-oesophageal reflux. None was hypocalcaemic. Although stimulation of laryngeal receptors is known to produce reflex laryngeal closure, cough is the usual response during wakefulness. Treatment aimed at reducing upper airway irritation and voluntary inhibition of coughing appeared successful in reducing the incidence and severity of the episodes. Recognition of the condition is important as it may be confused with other causes of acute dyspnoea and it appears to respond to specific management.     

Post-extubation pulmonary function tests in detection of upper airway obstruction in drug-overdosed patients

A relatively high percentage of hypnotic-sedative drug-overdosed (HSDO) patients suffer post-extubation upper airway obstruction. Since early detection and treatment of these lesions is desirable, we studied 20 recently extubated (within 24 hours) as well as 11 non-intubated HSDO patients employing flow-volume loops and spirometry. Abnormalities in tests for upper airway obstruction were common in both groups but only in the four post-extubation patients with clinically suspected upper airway obstruction was an inspiratory plateau by flow volume loops found. In addition, three of these four patients had mid-VC ratios greater than 1.25. We conclude that the Inspiratory flow volume loop and the mid-VC ratio may help in detecting post-extubation upper airway obstruction in lethargic, HSDO patients.     

Effect of laryngeal anesthesia on pulmonary function testing in normal subjects

Pulmonary function tests (PFT) were performed on 11 normal subjects before and after topical anesthesia of the larynx. The PFT consisted of flow volume loops and body box determinations of functional residual capacity and airway resistance, each performed in triplicate. After the first set of tests, cotton pledgets soaked in 4% lidocaine were held in the pyriform sinuses for 2 min to block the superior laryngeal nerves. In addition, 1.5 ml of 10% cocaine was dropped on the vocal cords via indirect laryngoscopy. PFT were repeated 5 min after anesthesia. Besides routine analysis of the flow volume loops, areas under the inspiratory (Area I) and expiratory (Area E) portions of the loops were calculated by planimetry. Area I, peak inspiratory flow (PIF), as well as forced inspiratory flow at 25, 50, and 75% forced vital capacity (FVC), decreased after anesthesia. Peak expiratory flow decreased after anesthesia, but Area E and forced expiratory flow at 25, 50, and 75% FVC were unchanged. This protocol also was performed in 12 normal subjects with isotonic saline being substituted for the lidocaine and cocaine. In this group, no significant differences were observed when flow volume loop parameters were compared before and after topical application of saline. In 5 spontaneously breathing anesthetized dogs, posterior cricoarytenoid muscle and afferent superior laryngeal nerve activity were recorded before and after laryngeal anesthesia performed with the same procedure used in the human subjects. Laryngeal anesthesia resulted in a substantial decrease or a complete disappearance of afferent SLN activity recorded during unobstructed and obstructed respiration. The data suggest that laryngeal receptors help modulate upper airway patency in man.     

Retropharyngeal hematoma as a new cause of acute upper airway obstruction in rheumatoid arthritis

A patient with severe rheumatoid arthritis (RA) receiving chronic anticoagulation therapy developed acute life threatening airway obstruction. The source of obstruction was a retropharyngeal hematoma compressing the upper airway rather than acute laryngeal dysfunction from the patient's RA. Our case illustrates a new cause of acute stridor and airway obstruction in RA. Publications on upper airway obstruction in RA and airway obstruction secondary to retropharyngeal hematoma are discussed.     

Upper airway dysfunction in olivopontocerebellar atrophy.

We report the findings in a patient known to have olivopontocerebellar atrophy who developed respiratory distress, inspiratory stridor, and maximum inspiratory and expiratory flow volume loops. Treatment with carbidopa-levodopa gave symptomatic relief.     

The ability of noninvasive methods to detect and quantify laryngeal obstruction

The ability of the noninvasive methods forced oscillation technique (Rosc), spirometry and flow-volume curves to detect and quantify laryngeal obstruction, using assessment of orolaryngeal (upper) airway resistance (Rol) as reference, was compared in 55 patients with various laryngeal diseases. Statistical analysis was performed by means of sensitivity/specificity, simple regression, stepwise regression and stepwise logistic regression. The results showed that the ability to detect a laryngeal obstruction was acceptable and that Rosc-Insp, peak inspiratory flow (PIF) and forced inspiratory volume in one second (FIV1) seemed to be the best variables for detection of a laryngeal obstruction. None of the studied noninvasive methods appeared to be adequate for quantification of laryngeal obstruction.     

Postobstruction pulmonary edema

Several occurrences of pulmonary edema following relief of acute upper airway obstruction have been reported. The edema is associated with normal cardiac filling pressures and responds promptly to conservative therapy. Its origin may be attributed to the cardiopulmonary effects of the vigorous inspiratory effort that the spontaneously breathing patient generates to overcome respiratory obstruction (the Müller maneuver). A patient with postobstruction pulmonary edema complicated by hypovolemia and myocardial infarction is described. Prompt invasive hemodynamic monitoring in selected high-risk patients is suggested.     

Bilateral vocal cord paralysis with respiratory failure. A presenting manifestation of bronchogenic carcinoma

A patient with lung cancer presented with upper airway obstruction and hypercapnic respiratory failure resulting from bilateral vocal cord paralysis. Computed tomography demonstrated tumor extension into the superior mediastinum, with probable disruption of both recurrent laryngeal nerves. Unlike the more common unilateral cord paralysis, bilateral cord dysfunction is often associated with preservation of voice and varying degrees of stridor that may lead to potentially life-threatening delays in diagnosis and treatment. Proper management requires urgent translaryngeal intubation if airway obstruction is high grade, with subsequent consideration of laryngeal surgical procedures for long-term care.     

Diagnosis of upper airway obstruction by pulmonary function testing.

We compared 11 patients with upper airway obstruction (obstruction at or proximal to the carina) to 22 patients with chronic obstructive pulmonary disease and to 15 normal subjects utilizing spirometry, lung volumes, airway resistance, maximal voluntary ventilation, single-breath diffusion capacity, and maximal inspiratory and expiratory flow-volume loops. Four values usually distinguished patients with upper airway obstruction: (1) forced inspiratory flow at 50 percent of the vital capacity (FIF50%) less than or equal to 100 L/min; (2) ratio of forced expiratory flow at 50 percent of the vital capacity of the FIR50% (FEF50%/FIF50%) larger than or equal to 1; (3) ratio of the forced expiratory volume in one second measured in milliliters to the peak expiratory flow rate in liters per minute (FEV1/PEFR) larger than or equal to 10 ml/L/min; and (4) ratio of the forced expired volume in one second to the forced expired volume in 0.5 second (FEV1/FEV0.5) larger than or equal to 1.5. The last ratio can be determined with a simple spirometer.     

Alveolar pressure and airway resistance during maximal and submaximal respiratory efforts

A digital computing technique was used to extract continuous calculations of average alveolar pressure and airway resistance from body plethysmographic measurements during forced inspiratory and expiratory vital capacity maneuvers and tidal breathing in human subjects. Derived alveolar pressures were similar to those obtained using an interrupter technique (linear regression slope, 0.99 +/- 0.02; r = 0.98) and by comparison with esophageal pressure measurements. Studies in normal subjects revealed a characteristic pattern of increasing airway resistance throughout the expiratory phases of maximal and submaximal respiratory maneuvers, with maximal resistance of 33 to 110 cm H2O/L/s at low lung volumes during forced vital capacities. In contrast, inspiratory resistance remained low and constant throughout maximal and submaximal inspiratory maneuvers. Patients with COPD showed substantially higher inspiratory and expiratory resistances. In three patients with flow-volume loops suggestive of variable extrathoracic upper airway obstruction, measurements of alveolar pressure and airway resistance made it clear that two of the patients had upper airway obstruction, whereas the other was exerting an inadequate effort. We conclude that this noninvasive technique provides valid estimates of alveolar pressure and airway resistance continuously throughout both phases of the respiratory cycle over a wide range of volumes and flow rates. It may prove to be useful in the assessment of effort and airway obstruction in patients with a variety of pulmonary conditions.     

Reversibility of upper airway obstruction after levodopa therapy in Parkinson's disease

Serial flow-volume loops obtained in a 66-year-old patient with Parkinson's disease and recurrent episodes of dyspnea revealed a pattern consistent with upper airway obstruction, reversible after oral intake of levodopa. This observation shows that extrapyramidal involvement of the striated upper airway musculature may limit airflow and cause respiratory symptoms. Persistence of flow oscillations on the flow-volume loop contour after reversal of upper airway obstruction and dyspnea should be considered to reflect upper airway dysfunction with possibly serious consequences.     

Upper airways obstruction with bilateral vocal cord paralysis.

In ten patients with bilateral vocal cord paralysis, we demonstrated variable extrathoracic airway obstruction. The ratio of forced expiratory flow at 50 percent vital capacity to forced inspiratory flow at the same lung volume (VE50/VI50) was 1.65 +/- 0.77 (mean +/- 1 SD). There was marked variability of inspiratory flow obstruction with a mean VI50 of 1.63 +/- 0.75 liters/ sec and a range from 0.9 liters/sec to 3.2 liters/sec. Nine of the ten patients required tracheostomy for symptoms of dyspnea. Follow-up flow volume loops were obtained to document the effects of surgical intervention and tracheostomy.     

Extrathoracic obstruction and hypoxemia occurring during exercise in a competitive female cyclist

A 22-year-old competitive female cyclist complained of cough, chest tightness, and wheeze during high-intensity exercise that had previously been diagnosed as exercise-induced bronchospasm (EIB). A loud stridor, a sensation of her "throat closing," and severe dyspnea developed during maximal cycling exercise with concomitant reductions in both inspiratory and expiratory flow rates. A decrease of 25 L/min (26%) in minute ventilation and arterial hypoxemia (PaO(2) decrease, 93 to 76.5 mm Hg) resulted from this obstruction. Spontaneous tidal flow-volume loops (FVLs) during exercise exhibited a sawtooth pattern during inspiration, and substantial drops in flow rates after the stridor developed. However, maximal FVLs were unchanged from baseline following exercise, indicating that the obstruction was not EIB. We suggest that the continuous measurement of spontaneous breath-by-breath tidal FVLs may be a useful diagnostic tool for the identification of exercise-induced extrathoracic obstruction. Additionally, extrathoracic obstruction should be considered as an uncommon but potential cause of inadequate ventilation and arterial hypoxemia during exercise.     

Tracheomalacia and bronchomalacia associated with Larsen syndrome

Bronchomalacia has not previously been described in association with Larsen syndrome. In this article, three children with Larsen syndrome are reported. All three patients have tracheomalacia, and one of them has diffuse bronchomalacia diagnosed at flexible fiberoptic bronchoscopy. The patients' symptoms of airway obstruction include stridor, cyanosis, apnea, and recurrent pneumonias. Recognition of these abnormalities may allow the institution of supportive therapy.     

Spasmodic croup in the adult

Recurrent inspiratory stridor, for which there appears to be no organic basis, can present a serious medical problem. We measured the changes in cross-sectional area of the glottic aperture during the respiratory cycle in a patient with recurrent inspiratory stridor when she was well, during a spontaneous attack, and during one induced with histamine aerosol. The glottis was visualized using a fiberoptic bronchoscope passed transnasally and attached to a video camera and tape recorder. During stridor there was marked constriction of the glottis on inspiration and phase reversal of the normal movements of the vocal cords with respect to respiration. Intermittent positive pressure ventilation (IPPV) and continuous positive airway pressure (CPAP) applied during stridor, in the absence of inspiratory effort, reversed the glottic narrowing. Pulmonary resistance (RL) on inspiration was elevated during stridor and returned to normal during IPPV and CPAP. Expiratory RL was normal throughout. Our results show that stridor in this patient was due to dynamic inspiratory constriction of the vocal cords. Glottic constriction could be induced by histamine aerosol and reversed when lung inflation was unaccompanied by inspiratory effort during IPPV and CPAP. Recognition and appropriate management of this condition may avoid potentially dangerous therapeutic interventions.     

Diagnosis and Nd-YAG laser treatment of unsuspected malignant tracheal obstruction

Thirteen adult patients underwent palliative Nd-YAG laser treatment for relief of severe dyspnea due to malignant endotracheal obstruction. Three of the 13 patients had underlying chronic airflow obstruction (CAO) due to diffuse obstructive pulmonary disease. Despite dyspnea, cough, wheezing, stridor and/or hemoptysis, the diagnosis was delayed because of a normal chest roentgenogram in eight patients and nondiagnostic pulmonary function studies (including maximal expiratory and inspiratory flow-volume loops) in all three patients with CAO and in four of ten patients without CAO. The location of the tumor was extrathoracic in two patients, including one with CAO; intrathoracic in seven patients, including two with CAO; and combined extra- and intrathoracic in four. Tracheal diameter increased from 3.5 +/- 1.0 mm before, and to 9.8 +/- 2.0 mm after single or multiple laser treatments. Increased patency of the trachea after laser surgery was associated with improvement in expiratory and/or inspiratory flow rates and with symptomatic relief in all patients which persisted for 14.1 +/- 8.7 months (range four to 48 months). These results indicate that severe symptomatic narrowing of the extra- and/or intrathoracic trachea to a diameter of 2 to 5 mm may not be detected by conventional chest radiography or even by sensitive physiologic tests, especially in patients with underlying CAO. The resultant delay in diagnosis defers possible relief of disabling symptoms with palliative therapy, including Nd-YAG laser photocoagulation.     

Flow-volume curve abnormalities and obstructive sleep apnea syndrome

Recent reports have suggested that flow volume curve abnormalities may be of interest in the diagnosis of obstructive sleep apnea syndromes by showing either extrathoracic airway obstruction (ratio of expiratory flow to inspiratory flow at 50 percent of forced vital capacity [FEF50/FIF50] exceeding 1) or upper airway fluttering (indicated by a sawtooth aspect on the mid-half of the inspiratory part of the curve) or both. In our study, 57 patients referred for a suspected sleep apnea syndrome (SAS) underwent conventional spirometry, assessment of flow-volume curves, ENT examination, and polysomnography. Thirty patients had an obstructive SAS, four patients a central SAS, and 23 patients no SAS. Signs of upper airway fluttering (the sawtooth sign) were present in 61 percent of the patients with obstructive SAS and in 46 percent of the patients without obstructive SAS (central SAS or no SAS). Signs of extrathoracic upper airway obstruction (FEF50/FIF50 greater than 1) were present in 67 percent of the patients with obstructive SAS and in 71 percent of the patients without obstructive SAS. These results suggest that upper airway abnormalities, as reflected by abnormal flow volume curves, are not always associated with obstructive SAS; they favor the hypothesis of a central component in the mechanism of upper airway occlusion during sleep.     

Severe asthma associated with myasthenia gravis and upper airway obstruction.

An unusual association of asthma and myasthenia gravis (MG) complicated by tracheal stenosis is reported. The patient was a 35-year-old black woman with a history of severe asthma and rhinitis over 30 years. A respiratory tract infection triggered a life-threatening asthma attack whose treatment required orotracheal intubation and mechanical ventilatory support. A few weeks later, tracheal stenosis was diagnosed. Clinical manifestations of MG presented 3 years after her near-fatal asthma attack. Spirometry showed severe obstruction with no response after inhalation of 400 microg of albuterol. Baseline lung function parameters were forced vital capacity, 3.29 L (105% predicted); forced expiratory volume in 1 second (FEV1), 1.10 L (41% predicted); maximal midexpiratory flow rate, 0.81 L/min (26% predicted). FEV1 after administration of albuterol was 0.87 L (32% predicted). The patient's flow-volume loops showed flattened inspiratory and expiratory limbs, consistent with fixed extrathoracic airway obstruction. Chest computed tomography scans showed severe concentric reduction of the lumen of the upper thoracic trachea.