Elucidating nonlinear baroreflex and respiratory contributions to heart rate variability in obstructive sleep apnea syndrome

Using a Volterra-Wiener model and the Laguerre expansion technique, we estimated in a previous study the parameters that characterize linear and the second order effects of respiration ("RSA") and arterial blood pressure ("ABR") on heart rate. RSA and ABR gains were significantly lower in Obstructive Sleep Apnea (OSA) patients than in normal subjects. During sleep, ABR gain increased in normals but remained unchanged in OSA. In the present work, we investigated the physiological interpretation of the nonlinear components of the described model of heart rate variability, by means of simulation on the computed linear and nonlinear kernels. Our results indicate that the 2^ndorder kernels reflect specific characteristics of the RSA and ABR mechanisms, such as a RSA frequency response dependence upon tidal volume, saturation in the ABR-Blood Pressure relation, and respiratory modulation of ABR.

Closed-loop minimal model analysis of the cardiovascular response to transient arousal from sleep in healthy humans

In a previous work we reported discrepancies in the cardiovascular response to arousal from NREM sleep between OSAS patients and healthy controls. The long lasting cardiac sympathetic increase observed in normals was not present in the OSAS group, whereas the peripheral vasculature reaction was similar between the two groups. Analysis of REM arousal revealed that there was a similar temporary cardiac sympathetic impairment in the control group. In this work we have implemented a model-based time domain system identification method to assess the mechanisms involved in this reaction to arousal from both NREM and REM sleep in a group of healthy subjects. The use of time-varying techniques has enabled us to characterize the arousal reaction by analyzing the change in shape of the impulse responses of the system. The mechanisms regulating respiration and vascular effects on heart rate (respiratory sinus arrhythmia or RSA and arterial baroreflex or ABR, respectively) were the most affected by NREM arousal, likely as a result of the return of the wakefulness stimulus. The effect observed on the cardiac influence on the vasculature (circulatory dynamics, CID) was attributed to a change in the dominant mechanism prevailing in its dynamics.

Microscopic pulmonary embolisation of an indwelling central venous catheter with granulomatous inflammatory response

Indwelling catheters can disintegrate into tiny fragments and embolise. Once the fragments are detected radiographically, they can be removed using vascular intervention techniques. Rarely, indwelling catheters dwindle into inextricable pieces that embolise into minute pulmonary vessels and lymphatics, causing granulomatous changes microscopically. The present study reports a 54-yr-old female who had received several indwelling central lines during several abdominal surgeries over a 5-yr period. The patient developed a noncaseating granulomatous skin lesion followed by exertional dyspnoea a few months later. Chest radiographs and computed tomography showed diffuse interstitial infiltrates. Open lung biopsy showed two types of granulomas: 1) peri-lymphangitic and peri-bronchiolar non-necrotising granulomas consistent with sarcoidosis; and 2) distinct foreign body granulomas. In some of the foreign body granulomas, confocal Raman spectroscopy identified the presence of bisphenol-A-polycarbonate, a polymer commonly used in biomedical devices. The patient improved following treatment with prednisone followed by methotrexate. The present case illustrates an interesting combination of two causes of granulomatous disease, the importance of examining all biopsy specimens from sarcoidosis patients for foreign particles and the rare occurrence of microscopic embolisation of catheter fragments to the lung with foreign-body giant cell reaction to them.

Determinants of heart rate variability in obstructive sleep apnea syndrome during wakefulness and sleep

Heart rate variability (HRV) is mediated by at least three primary mechanisms: 1) vagal feedback from pulmonary stretch receptors (PSR), 2) central medullary coupling between respiratory and cardiovagal neurons (RCC), and 3) arterial baroreflex (ABR)-induced fluctuations. We employed a noninvasive experimental protocol in conjunction with a minimal model to determine how these sources of HRV are altered in obstructive sleep apnea syndrome (OSAS). Respiration, heart rate, and blood pressure were monitored in eight normal subjects and nine untreated OSAS patients in relaxed wakefulness and stage 2 and rapid eye movement sleep. A computer-controlled ventilator delivered inspiratory pressures that varied randomly from breath to breath. Application of the model to the corresponding subject responses allowed the delineation of the three components of HRV. In all states, RCC gain was lower in OSAS patients than in normal subjects (P < 0.04). ABR gain was also reduced in OSAS patients (P < 0.03). RCC and ABR gains increased from wakefulness to sleep (P < 0.04). However, there was no difference in PSR gain between subject groups or across states. The findings of this study suggest that the adverse autonomic effects of OSAS include impairment of baroreflex gain and central respiratory-cardiovascular coupling, but the component of respiratory sinus arrhythmia that is mediated by lung vagal feedback remains intact.

Measurement of lung mechanics at different lung volumes and esophageal levels in normal subjects: effect of posture change

Lung elastance and resistance increase in the supine posture. To evaluate the effects of change in posture on regional lung mechanics at different lung volumes, lung elastance and resistance were measured at graded volume subdivisions and three esophageal levels at seated and supine body positions, using the esophageal balloon technique. Volumes were adjusted to be the same in both postures. In general, lung elastance (both static and dynamic) tended to be higher in supine posture and uniform at all lung volumes, except at 80% vital capacity, where it increased sharply. The ratio of dynamic to static lung elastance was slightly higher at the cephalad esophageal level, where regional flow rates and relative volume expansion are lower. Lung resistance varied inversely with lung volume but was higher at corresponding volume subdivisions in the supine posture. It decreased at more cephalad esophageal levels, where volume expansion and flow are less. Thus, the increase in regional flow at low volume subdivisions (most marked in the supine position) also contributed to higher lung resistance at these volumes. These findings are explained on the basis of a combination of Newtonian physics as well as nonlinear viscoelastic properties of the lung as applied to regional flow and volume expansion.

Respiratory muscle strength, lung function, and dyspnea in patients with sarcoidosis

BACKGROUND

Sarcoidosis is a systemic granulomatous disorder that is estimated to involve the skeletal muscles in up to 50% of patients. There is little information on the relationship among respiratory muscle strength, lung volumes, and the degree of dyspnea in patients with sarcoidosis.

DESIGN AND PATIENTS

Lung function and maximal respiratory muscle force generation were measured in 36 patients with sarcoidosis (24 patients with pulmonary parenchymal infiltration) and 25 control subjects free of cardiorespiratory disease. Dyspnea in the sarcoidosis patients was quantitated by a score based on an activity tolerance assessment scale (ranging from rest to climbing hills or stairs).

SETTING

Outpatient clinics of two teaching hospitals.

RESULTS

Mean FVC, maximal voluntary ventilation, total lung capacity (TLC), functional residual capacity, residual volume (RV), and diffusing capacity of the lung for carbon monoxide (DLCO) were all at least 16% less than corresponding control values (in all cases, p < 0.001), while maximal inspiratory mouth pressure (PImax) and maximal expiratory mouth pressure (PEmax) were 37% and 39% less, respectively, than control values (both at p < 0.0001). PImax and PEmax declined with increasing dyspnea in a more graded, steady manner than did spirometric and DLCO values. For all measurements, however, the lowest mean values were found in patients with the most severe level of dyspnea. Strong inverse relationships were observed between PEmax and PImax with dyspnea level (p < 0.0001 and p < 0.01, respectively). Both PImax and PEmax correlated best with absolute values of FVC, while only PEmax correlated with RV (absolute and percent predicted) and percent predicted values of TLC.

CONCLUSIONS

Maximal respiratory pressures correlate more closely with dyspnea level than lung volumes and DLCO. Since dyspnea is the most common presentation in early to moderately advanced sarcoidosis, respiratory pressures may be a more reliable index of functional work capacity and reflection of activities of daily living than standard tests of lung function.

Lung mechanics in individuals with spinal cord injury: effects of injury level and posture

Individuals with spinal cord injury (SCI) exhibit reduced lung volumes and flow rates as a result of respiratory muscle weakness. These features have not, however, been investigated in relation to the combined effects of injury level and posture. Changes in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), FEV(1)/FVC, forced expiratory flow at 50% vital capacity (FEF(50)), inspiratory capacity (IC), and expiratory reserve volume (ERV) were assessed by injury level in the seated and supine positions in 74 individuals with SCI. The main findings were 1) FVC, FEV(1), and IC increased with descending SCI level down to T(10), below which they tended to level off; 2) supine values of FVC and FEV(1) tended to be larger in the supine compared with the seated posture down to injury level T(1), caudad to which they were less than when seated; 3) IC increased proportionately more down to injury level L(1), below which it declined slightly and plateaued; 4) ERV was measurable even at high cervical injuries, was generally smaller in the supine position, reached peak values in both positions at T(10) injury level, and then rapidly declined at lower levels; 5) when subjects were separated according to current, former, and never smokers, only formerly smoking paraplegic individuals demonstrated spirometric values significantly less than paraplegic individuals who never smoked. Changes in spirometric measurements in SCI are dependent on injury level and posture. These findings support the concept that the increase in vital capacity in supine position is related to the effect of gravity on abdominal contents and increase in IC.

Long term non-invasive ventilation in the community for patients with musculoskeletal disorders: 46 year experience and review

BACKGROUND

A study was undertaken to assess the long term physiological and clinical outcome in 79 patients with musculoskeletal disorders (73 neuromuscular, six of the chest wall) who received non-invasive ventilation for chronic respiratory failure over a period of 46 years.

METHODS

Vital capacity (VC) and carbon dioxide tension (PCO(2)) before and after initiation of ventilation, type and duration of ventilatory assistance, the need for tracheostomy, and mortality were retrospectively studied in 48 patients who were managed with mouth/nasal intermittent positive pressure ventilation (M/NIPPV) and 31 who received body ventilation. The two largest groups analysed were 45 patients with poliomyelitis and 15 with Duchenne's muscular dystrophy. Twenty five patients with poliomyelitis received body ventilation (for a mean of 290 months) and 20 were supported by M/NIPPV (mean 38 months). All 15 patients with Duchenne's muscular dystrophy were ventilated by NIPPV (mean 22 months).

RESULTS

Fourteen patients with poliomyelitis on body ventilation (56%) but only one on M/NIPPV, and 10 of 15 patients (67%) with Duchenne's muscular dystrophy eventually received tracheostomies for ventilatory support. Five patients with other neuromuscular disorders required tracheostomies. Twenty of 29 tracheostomies (69%) were provided because of progressive disease and hypercarbia which could not be controlled by non-invasive ventilation; the remaining nine were placed because of bulbar dysfunction and aspiration related complications. Nine of 10 deaths occurred in patients on body ventilation (six with poliomyelitis), although the causes of death were varied and not necessarily related to respiratory complications. A proportionately greater number of patients on M/NIPPV (67%) reported positive outcomes (improved sense of wellbeing and independence) than did those on body ventilation (29%, p<0.01). However, other than tracheostomies and deaths, negative outcomes in the form of machine/interface discomfort and self-discontinuation of ventilation also occurred at a rate 2.3 times higher than in the group who received body ventilation. None of the six patients with chest wall disorders (all on M/NIPPV) required tracheostomy or died. Hospital admission rates increased nearly eightfold in patients receiving body ventilation (all poliomyelitis patients) compared with before ventilation (p<0.01) while in those supported by M/NIPPV they were reduced by 36%.

CONCLUSIONS

Non-invasive ventilation (NIV) in the community over prolonged periods is a feasible although variably tolerated form of management in patients with neuromuscular disorders. While patients who received body ventilation were followed the longest (mean 24 years), the need for tracheostomy and deaths occurred more often in this group (most commonly in the poliomyelitis patients). Despite a number of discomforts associated with M/NIPPV, a larger proportion of patients experienced improved wellbeing, independence, and ability to perform daily activities.

Expiratory flow limitation during spontaneous breathing: comparison of patients with restrictive and obstructive respiratory disorders

BACKGROUND AND STUDY OBJECTIVES

Comparison of tidal and forced expiratory flow-volume (V-V) curves has inherent technical problems in the characterization of expiratory flow limitation. In addition, patients with neuromuscular disorders may be unable to perform forced expiratory maneuvers because of muscle weakness or poor coordination. A recently developed simple, noninvasive technique that avoids these problems was used to detect expiratory flow limitation at rest in 19 seated patients with restrictive respiratory (13 with musculoskeletal) disorders (RD) and 20 with chronic obstructive airway disease (COAD).

SETTING

A large rehabilitation hospital for the care of patients with chronic musculoskeletal and respiratory disorders.

INTERVENTIONS AND MEASUREMENTS

The method consisted of applying negative pressure of about 5 cm H2O at the airway opening during expiration and comparing the ensuing V-V curve to the preceding tidal V-V curve.

RESULTS

While nine patients with COAD demonstrated flow limitation, only one patient with RD did so. Patients with expiratory flow limitation exhibited various contours of the control tidal expiratory V-V curve. Thus, inspection of the tidal V-V curve is not a reliable means of detecting expiratory flow limitation.

CONCLUSIONS

We conclude that expiratory flow limitation during resting breathing is common in patients with COAD but not in patients with RD.

Pulmonary physiology in interstitial lung disease: recent developments in diagnostic and prognostic implications

Pulmonary function changes in interstitial lung disease are characterized by loss of lung volume, increase in ratio of forced expiratory volume in 1 second to forced vital capacity, and decrease in carbon monoxide diffusion capacity. Recent developments in the assessment of respiratory mechanics in infiltrative lung disease have elucidated volume and flow dependence of lung and total respiratory resistance and elastance related to the viscoelastic properties of the respiratory system. A new, simple test of applying negative expiratory pressure at the mouth during tidal expiration can be used to generate expiratory flow-volume curves to detect flow limitation in patients with restrictive as well as obstructive disorders. This method is useful in patients who are weak, uncoordinated, or who cough during forced maneuvers. Poor prognostic signs in interstitial lung disease include male gender, paucity of lymphocytes on bronchoalveolar lavage, extensive radiographic infiltration, absence of cellular histologic findings on lung biopsy, presence of right-axis deviation, persistent or progressive decrease in lung volumes, and diffusion capacity of carbon monoxide.

Contribution of lung and chest wall mechanics following emphysema resection

OBJECTIVE

To determine the contributions of (1) chest wall (Pcw) and (2) lung elastic recoil pressure (PL) to (3) total elastic recoil pressure exerted by the respiratory system (Prs) in 18 patients (12 men) aged 66 +/- 6 years (mean +/- 1 SD) with severe emphysema who underwent video-assisted thoracoscopic bilateral lung volume reduction surgery under paralyzed (vecuronium) general anesthesia (isoflurane).

DESIGN

We measured preoperative and 6-week postoperative lung function studies, and intraoperative inspiratory lung conductance (GL), PL, Pcw, and Prs (cm H2O) at end-expiratory lung volume (EELV), EELV plus 0.60 +/- 0.0 L, and EELV plus 1.15 +/- 0.0 L. All values are mean +/- SEM.

RESULTS

Preoperative vs postoperative FVC was 1.9 +/- 0.1 L vs 2.3 +/- 0.1 L (p = 0.03); FEV1 was 0.6 +/- 0.1 L vs 0.9 +/- 0.1 L (p < 0.02); total lung capacity was 7.4 +/- 0.4 L vs 5.9 +/- 0.3 L (p < 0.001); functional residual capacity was 5.7 +/- 0.4 L vs 4.4 +/- 0.2 L (p = 0.001). At EELV preoperative vs postoperative, PL was 0.0 +/- 0.3 vs 1.1 +/- 0.05 (p = 0.04), Pcw was 5.0 +/- 0.7 vs 2.4 +/- 0.9 (p = 0.02), and Prs was 5.0 +/- 0.8 vs 3.5 +/- 0.7 (p = 0.08). AT EELV plus 0.60 L, PL was 3.2 +/- 0.6 vs 6.1 +/- 0.9 (p < 0.001), Pcw was 8.8 +/- 0.8 vs 7.0 +/- 0.9 (p = 0.12), and Prs was 12.0 +/- 0.8 vs 13.1 +/- 0.7 (p = 0.80). At EELV plus 1.15 L, PL was 6.8 +/- 0.9 vs 10.3 +/- 1.1 (p < 0.001), Pcw was 13.5 +/- 1.0 vs 11.2 +/- 1.2 (p = 0.12), and Prs was 20 +/- 1.2 vs 21.5 +/- 1.0 p = 0.93). AT EELV plus 0.06 L, GL was 0.09 +/- 0.00 L/S/cm H2O vs 0.16 +/- 0.01 (p < 0.01). At EELV plus 1.15 L, GL was 0.12 +/- 0.01 vs 0.21 +/- 0.03 (p < 0.05) with similar preoperative vs postoperative GL/PL slopes.

CONCLUSION

The increase in PL and decrease in Pcw following LVRS for emphysema may be responsible for the increase in spirometry and airway conductance.

Immediate response to inspiratory resistive loading in anesthetized patients with kyphoscoliosis: spirometric and neural effects

In kyphoscoliosis (KS), lung volumes are reduced, respiratory elastance and resistance are increased, and breathing pattern is rapid and shallow, attributes that may contribute to defense of tidal volume (VT) in the face of inspiratory resistive loading. The control of ventilation of 12 anesthetized patients about to undergo corrective spinal surgery was compared to that of 11 anesthetized patients free of cardiothoracic disease during quiet breathing and the first breath through one of three linear resistors. Mean forced vital capacity (FVC) of the KS group was 48% that of the controls (C). Passive elastance (Ers) and active elastance and resistance (E'rs and R'rs, respectively) were computed according to previously described techniques (Behrakis PK, Higgs BD, Baydur A, Zin WA, Milic-Emili J (1983) Active inspiratory impedance in halothane-anesthetized humans. J Appl Physiol 54: 1477-1481). Baseline tidal volume VT, inspiratory duration Tl, expiratory duration TE, duration of total breathing cycle TT, and inspiratory duty cycle TI/TT were significantly reduced, while VE was slightly decreased in the KS. Ers, E'rs, and R'rs, were, respectively, 72, 69, and 89% greater in the KS. Driving pressure (Pmus) was derived from the equation of motion, using active values of respiratory elastance. With resistive loading, there was greater prolongation of TI in the C, while percent reduction in VT and minute ventilation VE was less in KS. Compensation in both groups was achieved through three changes in the Pmus waveform. (1) Peak amplitude increased. (2) The duration of the rising phase increased. (3) The rising Pmus curve became more concave to the time axis. These changes were most marked with application of the highest resistance in both groups. Peak driving pressure and mean rate of rise of Pmus were greater in the KS. Increased intrinsic impedance, Pmus, and differences in changes in neural timing in anesthetized kyphoscoliotics contribute to modestly greater VT defense, compared to that of anesthetized subjects free of cardiorespiratory disease.

Fatal intrathoracic hemorrhage in a patient with von Recklinghausen's disease

Neurofibromatosis can involve the mediastinum. A 44-year-old woman with a dumbbell-shaped mediastinal mass developed a large pleural effusion, respiratory failure and fatal hemoptysis. Autopsy revealed systemic neurofibromatosis involving the mediastinum and pleura. Mediastinal and pleural hemorrhage probably occurred as a result of an eroded thoracic artery. Massive hemorrhage in mediastinal neurofibromatosis occurs uncommonly but with potentially fatal results.

Strategies for home-assisted ventilation

The Council on Scientific Affairs of the California Medical Association presents the following epitomes of progress in chest diseases. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and clinical importance. The items are presented in simple epitome, and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, researchers, and scholars to stay abreast of progress in medicine, whether in their own field of special interest or another. The epitomes included here were selected by the Advisory Panel to the Section on Chest Diseases of the California Medical Association, and the summaries were prepared under the direction of Dr Cosentino and the panel.

Respiratory mechanics by the passive relaxation technique in conscious healthy adults and patients with restrictive respiratory disorders

The passive relaxation single-breath technique has been used primarily in anesthetized human subjects to measure total respiratory system elastance and resistance. This method was used to assess the pressure-flow characteristics in 32 relaxed, conscious patients with restrictive respiratory disorders (20 with neuromuscular disease, 12 with sarcoidosis) and 27 similarly aged control subjects free of cardiothoracic disease. Using Rohrer's pressure-flow relationship during passive expiration, P/V = K1 + K2V, considerable curvilinear pressure-flow characteristics were found in both groups. These can be attributed to a combination of the upper airway and viscoelastic and elastoplastic behavior of the respiratory system. Despite the greater elastic recoil pressure (and respiratory elastance) of the restrictive patients, their pressure-flow characteristics were similar to those of the control subjects. These findings imply structural similarities in at least the lower airways, or in the effects of retractile forces along airways compensating for reduced lung volumes.

Passy-Muir tracheostomy speaking valve on ventilator-dependent patients

Communication for handicapped ventilator-dependent patients is a problem, not only for the patient but also for the healthcare personnel. The inability of these patients to vocalize is a paramount problem in their care. This study evaluates the efficacy of a one-way speaking valve on ventilator-dependent patients and evaluates the resulting effectiveness of their speech. Fifteen ventilator-dependent patients were fitted with the one-way Passy-Muir Tracheostomy Speaking Valve and their communicative skills and ease of vocalization were evaluated. This clinical evaluation was done by the patient, a speech pathologist, two nurses in charge of the patient, and the patient's private physician. No complications were observed in any of the patients. All 15 patients showed marked improvement, not only in speech intelligibility but in speech flow, the elimination of speech hesitancy, and speech time. This ability to communicate enhanced the care given by the healthcare personnel. In conclusion, use of the Passy-Muir Tracheostomy Speaking Valve restored verbal communicative skills of ventilator-dependent patients, facilitated care, and greatly enhanced the mental outlook of these patients without observed complications.

Control of ventilation, respiratory muscle strength, and granulomatous involvement of skeletal muscle in patients with sarcoidosis

Granulomatous involvement of skeletal muscle occurs in 50 to 80 percent of patients with sarcoidosis. How this may affect respiratory muscle function in sarcoidosis is not known. To attempt to answer this question, we compared respiratory function and muscle force generation, and control of ventilation in 12 untreated patients with 12 healthy, nonsmoking subjects. While seated, room air breathing, measurements included expiratory reserve volume (ERV), components of breathing pattern, and occlusion pressure at 1 s (P0.1). Three of nine patients who consented to muscle biopsy demonstrated granulomatous involvement on histologic examination, and Pmax values less than the group mean; however, some patients without muscle granulomas also demonstrated low Pmax values. Breathing pattern in the sarcoid patients was rapid and shallow, but not related to the degree of radiographic infiltration or respiratory elastance. Mean inspiratory flow (VT/TI), minute ventilation, and P0.1 were, in general, greater than in the control subjects, indicating an increase in central drive. There was a significant inverse correlation between FVC and P0.1, and a weak inverse relationship between ERV and P0.1. With no significant difference between group "effective impedances" (P0.1/(VT/TI)), findings indicate that in the sarcoidosis group, decreased muscle force generation was compensated for by an increase in central drive. Granulomatous infiltration may be one of many factors contributing to respiratory muscle weakness in sarcoidosis.

Decay of inspiratory muscle pressure during expiration in anesthetized kyphoscoliosis patients

The decay of pressure developed by the inspiratory muscles during expiration (PmusI) has not been studied in subjects with increased respiratory impedance such as in kyphoscoliosis. PmusI was compared in 11 anesthetized patients with kyphoscoliosis with that in 11 anesthetized normal subjects. PmusI was obtained according to the following equation: PmusI(t) = Ers.V(t) - K1V(t) - K2V2(t), where V is volume and V is airflow at any instant t during spontaneous expiration, Ers is the passive elastance, and K1V + K2V2 is the flow resistance (curvilinear in both groups because of the endotracheal tube and the intrinsic resistance in the kyphoscoliotics) of the total respiratory system. Ers was determined by the relaxation method and resistance from the ensuing V-V relationships during the ensuing relaxed expiration. Changes in impedance due to pliometric work done by the inspiratory muscles during relaxation were neglected. Subjects in both groups showed marked braking of expiratory flow by PmusI. The mean time for PmusI to decrease to 50 and 0% amounted to 17 and 8% less, respectively, in the kyphoscoliosis group. Average values for flow-resistive work in the control and kyphoscoliosis groups both amounted to approximately 40% of the elastic energy stored during inspiration. The remaining portion, used as negative work, amounted to approximately 60% in both groups. Expiratory braking in anesthetized kyphoscoliotic patients appears to be in proportion to their magnitude of elastic recoil and intrinsic flow resistance.

Respiratory muscle strength and control of ventilation in patients with neuromuscular disease

To assess the relationship between respiratory mechanics and muscle strength and control of ventilation in patients with neuromuscular disease (NMD), we compared PImax and PEmax at RV, FRC and TLC, total respiratory elastance (Ers) with VT, TI, TT, VE, VT/TI, TI/TT, P.01, and P.01/(VT/TI) effective impedance in 21 patients with NMD and 21 healthy control (C) subjects, in seated position breathing room air. Ers in NMD patients was 79 percent higher than in the C subjects. While TI, TT, and VT in NMD were approximately half the corresponding C values, P.01 was 66 percent greater than in the C subjects (both p less than 0.001). NMD PImax and PEmax ranged from 37 to 52 percent of corresponding C values, respectively. Despite significant respiratory muscle weakness, only 7 of 16 patients demonstrated a PaCo2 greater than 45 mm Hg. Ventilatory output in NMD was modulated by respiratory mechanics as indicated by the increased P.01. In spite of muscle weakness, central drive in patients with NMD is not decreased, and in fact, is often increased. VE is not an accurate measure of central drive because of abnormal intrinsic respiratory mechanics and the effects of conscious responses or reflexes.

Cardiorespiratory effects of endoscopic esophageal variceal sclerotherapy

Endoscopic variceal sclerotherapy (EVS) is an effective means of controlling variceal hemorrhage, which develops as a consequence of portal hypertension. While esophageal perforation, ulceration, strictures, and mediastinitis are potential complications associated with this procedure, it is not clear whether isolated pleuropulmonary events such as pleuritis, pneumonitis, and adult respiratory distress syndrome are causally related to the EVS. Endoscopy and sedation with the attendant risk of aspiration, particularly in the background of hepatic encephalopathy, may account for some of these events. Recent controlled studies of respiratory function demonstrate that EVS as such results in minor changes in gas exchange, lung volumes, and pulmonary and systemic hemodynamics. Most pulmonary complications have been reported with the use of sodium morrhuate sclerosant. Comparative studies among different sclerosants are necessary to evaluate relative safety. Finally, there have been rare reports of myocardial ischemia and pericarditis reported in association with EVS, but these are of a transient nature. Chest symptoms, roentgenographic pleuropulmonary changes, pulmonary hemodynamics, and cardiac perturbations are transient and should not preclude offering EVS to patients with variceal hemorrhage.

Respiratory mechanics in anesthetized young patients with kyphoscoliosis. Immediate and delayed effects of corrective spinal surgery

To our knowledge, the effects of corrective spinal surgery on total respiratory mechanics and its components in anesthetized patients with kyphoscoliosis have not been previously reported in detail. We studied 13 patients with kyposcoliosis; their mean (+/- SD) age was 24.7 +/- 2.1 years; eight underwent anterior and posterior spinal fusions (AF and PF, respectively) two weeks apart (group A), four underwent PF alone (group B), and one had a three-stage procedure. Mean total respiratory elastance (Ers), static and dynamic lung elastance (Est,L and Edyn,L, respectively), chest wall elastance (Ew), and lung resistance (RL) were derived according to previously described methodology. In group A, Ers and Ew increased by 39 percent and 58 percent, respectively, following AF and by 20 percent and 129 percent following PF, while Est,L and Edyn,L did not change or declined following PF. Lung resistance increased 19 percent and 41 percent by the end of AF and PF, respectively, in group A. In group B, Ew more than doubled, resulting in a 39 percent increase in Ers. Increases in Ers, Ew, and respiratory flow resistance observed at the time of spinal corrective surgery for kyphoscoliosis may result from rib cage trauma and changes in airway caliber related to microatelectasis and uneven distribution of mechanical properties within the lungs. Spinal correction results in immediate and short-term deterioration of respiratory mechanics measured under anesthesia.

Decline in respiratory function and experience with long-term assisted ventilation in advanced Duchenne's muscular dystrophy

We present 17 patients with advanced DMD who required long-term assisted ventilation. Eleven patients used part-time assisted ventilation. Five of the patients received BV and/or M-IPPV or N-IPPV between two and nine years before requiring full-time T-IPPV, while six others initially used part-time T-IPPV. One patient used all three modes before requiring full-time T-IPPV. Mean (+/- SD) FVC and rebreathe PCO2 at the outset of assisted ventilation were 0.62 +/- 0.20 L and 47.4 +/- 7.5 mm Hg, respectively. Clinical features were divided between symptoms suggesting respiratory muscle fatigue and sleep-related disordered breathing. We found that, while useful in early respiratory insufficiency, BV is associated with recurrent aspiration. In our experience, N-IPPV offers the safest and most convenient form of noninvasive ventilation. When the VC has decreased to about 300 ml, most patients will require full-time ventilation; T-IPPV is advised to provide airway access to suction secretions.

The effect of the halovest and body position on pulmonary function in quadriplegia

Pulmonary function (vital capacity) was measured in ten quadriplegics and ten normal subjects in the following situations: supine, sitting, supine with a halovest, and sitting with a halovest. When changing from the supine to sitting positions, vital capacity decreased in the quadriplegics and increased in normal subjects. The halovest significantly reduced the vital capacity in normal subjects, but had much less of a detrimental effect in quadriplegics. As a result of this prospective, controlled study, we conclude the following: (a) the compromised state of pulmonary function in quadriplegics is not a contraindication for the use of a halovest, (b) the halovest causes a significant (p less than 0.01) restriction in vital capacity in able bodied subjects, and (c) when tenuous pulmonary function exists in a quadriplegic, pulmonary mechanics are better in the supine position.

Respiratory elastic load compensation in anesthetized patients with kyphoscoliosis

To evaluate the effects of abnormal respiratory mechanics and neuromuscular drive on the various components of elastic load compensation, we studied 16 anesthetized patients with kyphoscoliosis whose mean passive and active respiratory elastance (Ers and E'rs, respectively), active respiratory resistance, and peak inspiratory occlusion pressure were, respectively, 89, 84, 100, and 37% greater and inspiratory duration (TI) 13% less than corresponding values in 13 anesthetized controls. Ers comprised approximately 66% of effective elastance (E*rs) in both groups. E'rs, reflecting the role of the force-length properties of the active inspiratory muscles in increasing the internal impedance, comprised 83.8 and 86.1% of E*rs in the kyphoscoliosis patients and controls, respectively (P less than 0.001). This demonstrates the influence of increased intrinsic elastance and resistance and decreased TI on tidal volume defense in kyphoscoliosis patients in the absence of vagal modulation. In some patients the difference between Ers and E*rs was substantial, despite an unchanged or even shortened TI, suggesting that the Hering-Breuer reflex may affect stability through ways other than altering TI (e.g., via graded volume-dependent "terminal inhibition"). Characteristics of elastic load compensation in anesthetized kyphoscoliosis patients are similar to those of anesthetized normal subjects.

Patient and family participation in the management of respiratory failure in Duchenne's muscular dystrophy

Mechanical ventilation is now considered a therapeutic option for respiratory failure associated with Duchenne's muscular dystrophy (DMD). Through the monitoring of forced vital capacity and PCO2, prediction of impending respiratory failure is possible. This knowledge allows the patient to choose institution of mechanical ventilation before acute respiratory failure or no intervention and preparation for a natural death. To assist patients and families in this decision making, a special clinic was established. Thirty adolescent boys with DMD were followed up. Eighteen boys reached the end stage of their disease. Three died of cardiac failure. Prediction of respiratory failure was possible in 14 of the remaining 15; 11 of the 15 were able to make educated choices regarding respirator assistance or a natural death. The clinic has shown that in the majority of cases, when properly educated, patients and families can be active participants in life-and-death decisions.

Gated radionuclide ventriculography in the evaluation of cardiac function in Duchenne's muscular dystrophy

Left ventricular ejection fractions were determined in 38 patients with Duchenne's muscular dystrophy. No significant correlation between the severity of respiratory dysfunction or age and cardiac function was seen. We suggest that the cardiac status of each patient should be evaluated separately from his respiratory status, particularly when long-term assisted ventilation is being considered.

Effect of posture on ventilation and breathing pattern during room air breathing at rest

We measured minute ventilation (VE), tidal volume (VT), mean inspiratory flow (VT/TI), and occlusion pressure (P.1) in 10 resting subjects breathing room air, in sitting, supine, right and left lateral positions, and compared them with corresponding data on static lung compliance [Cst(l)], dynamic lung compliance [Cdyn(l)], and pulmonary flow resistance [R(l)]. Highest values for VT, VE, VT/TI, P.1, and effective inspiratory impedance [P.1/(VT/Ti)] were observed in the supine posture. Values for P.1 and P.1/(VT/TI in lateral decubitus were intermediate to those obtained when seated and supine. While the increases in P.1 and P.1/(VT/TI) in recumbent postures were qualitatively similar to the decrease in Cdyn(l) and increase in R(l), there was no significant correlation between them, probably reflecting the complex relationship between P.1/(VT/TI) and lung compliance and resistance, as the former, in addition to lung mechanics, also depends on the shape of the inspiratory driving pressure wave, the active inspiratory impedance, the mechanics of the chest wall, and the duration of inspiration.

Validation of esophageal balloon technique at different lung volumes and postures

The esophageal balloon technique for measuring pleural surface pressure (Ppl) has recently been shown to be valid in recumbent positions. Questions remain regarding its validity at lung volumes higher and lower than normally observed in upright and horizontal postures, respectively. We therefore evaluated it further in 10 normal subjects, seated and supine, by measuring the ratio of esophageal to mouth pressure changes (delta Pes/delta Pm) during Mueller, Valsalva, and occlusion test maneuvers at FRC, 20, 40, 60, and 80% VC with the balloon placed 5, 10, and 15 cm above the cardia. In general, delta Pes/delta Pm was highest at the 5-cm level, during Mueller maneuvers and occlusion tests, regardless of posture or lung volume (mean range 1.00-1.08). At 10 and 15 cm, there was a progressive increase in delta Pes/delta Pm with volume (from 0.85 to 1.14). During Valsalva maneuvers, delta Pes/delta Pm also tended to increase with volume while supine (range 0.91-1.04), but was not volume-dependent while seated. Qualitatively, observed delta Pes/delta Pm fit predicted corresponding values (based on lung and upper airway compliances). Quantitatively there were discrepancies probably due to lack of measurement of esophageal elastance and to inhomogeneities in delta Ppl. At every lung volume in both postures, there was at least one esophageal site where delta Pes/delta Pm was within 10% of unity.

Partitioning of respiratory mechanics in young adults. Effects of duration of anesthesia

General anesthesia increases total respiratory elastance and flow resistance within minutes after induction. We determined if respiratory mechanics changed progressively during anesthesia by measuring total respiratory elastance and resistance and their respective lung and chest wall components in 10 young adults free of cardiorespiratory disease at the start and end of premedicated anesthesia administered for orthopedic surgery (isoflurane, enflurane, or halothane, minimal alveolar concentration approximately 1.5 in 60% N2O-40% O2; interval between measurements was 0.42 to 5.0 h, mean +/- SD = 2.08 +/- 1.56 h). Static lung recoil pressure, static total respiratory and lung elastance, dynamic lung elastance, chest wall elastance, and total respiratory and lung and chest wall resistances were measured during steady-state breathing (greater than 10 min after induction). Resistance of the endotracheal tube, pneumotachygraph and connectors were subtracted from the total flow resistance to obtain total intrinsic resistance. Average values of static lung recoil pressure and all elastances and chest wall resistance did not change significantly from start to end of the study, regardless of the elapsed time. Total respiratory and lung resistance increased by 49% (p less than 0.05) and 45% (p less than 0.02), respectively, but were not time-dependent. We conclude that lung static recoil and total respiratory and lung elastances did not change beyond the first 10 min after induction, regardless of duration of anesthesia. The increases in total respiratory and lung resistance were small, independent of duration of anesthesia, and may have been due to accumulated airway secretions.

Effect of esophageal variceal sclerotherapy (EVS) on lung function. A prospective controlled study

A prospective, controlled study to determine the short- and long-term effects of esophageal variceal sclerotherapy (EVS) on lung function was carried out on 11 patients with cirrhotic portal hypertension and variceal hemorrhage. Eleven patients with chronic liver disease undergoing diagnostic endoscopy served as controls. There was no difference in lung function tests and gas exchange in both the EVS or control groups after either procedure. No change in these parameters was noted during follow-up on continued sclerotherapy in the EVS group. Ventilation-perfusion scans and chest roentgenograms, performed before and after EVS, demonstrated no significant change. We conclude that in patients with stable liver disease and without hepatic failure, EVS does not result in serious short- and long-term impairment of lung function.

Immediate response to resistive loading in anesthetized humans

In eight spontaneously breathing anesthetized subjects (halothane: approximately 1 minimal alveolar concn; 70% N2O-30% O2), we determined 1) the inspiratory driving pressure by analysis of the pressure developed at the airway opening (Poao) during inspiratory efforts against airways occluded at end expiration; 2) the active inspiratory impedance; and 3) the immediate (first loaded breath) response to added inspiratory resistive loads (delta R). Based on these data we made model predictions of the immediate tidal volume response to delta R. Such predictions closely fitted the experimental results. The present investigation indicates that 1) in halothane-anesthetized humans the shape of the Poao wave differs from that in anesthetized animals, 2) the immediate response to delta R is not associated with appreciable changes in intensity, shape, and timing of inspiratory neural drive but depends mainly on intrinsic (nonneural) mechanisms; 3) the flow-dependent resistance of endotracheal tubes must be taken into account in studies dealing with increased neuromuscular drive in intubated subjects; and 4) in anesthetized humans Poao reflects the driving pressure available to produce the breathing movements.

Mechanisms of respiratory elastic load compensation in anesthetized humans

In anesthetized humans the nature of tidal volume (VT) compensation during elastic loading (as reflected in the difference between passive and effective respiratory elastances (Ers) and (E*rs), respectively) has not been fully elucidated. We assessed the relative contribution of various mechanisms contributing to VT compensation during linear elastic loading in 10 young anesthetized adults free of cardiorespiratory disease. Ers averaged 22.0 cmH2O X 1(-1), representing 64% of E*rs. Most of E*rs (84%) was comprised of the active elastance (E'rs), reflecting the major role played by the addition of force-length properties of inspiratory muscles to the internal impedance, and chest wall distortion played in the defense of VT. Of the remaining 16% of E*rs, the difference between E*rs and isotime E*rs, representing the contribution of prolongation of inspiratory time (TI) via the Hering-Breuer reflex, amounted to only 9%. Finally, the remainder of E*rs, which reflects the difference between E*rs and E'rs in the absence of vagal modulation, and attributed to several factors [shape of driving pressure wave, duration of control TI, and magnitude of E'rs and intrinsic flow resistance plus external resistances (Zin, Rossi, Zocchi, and Milic-Emili. J. Appl. Physiol. 57: 271-277, 1984)], amounted to less than 7%.

Active inspiratory impedance and load compensation: effects of duration of anesthesia

General anesthesia results in increases in respiratory elastance and flow resistance within 10-15 min after induction. Stabilization (compensation) of the respiratory system in the face of this added load is related to the addition of active (contractile) force-length and force-velocity properties to its internal impedance during inspiration. The difference between active (inspiratory) and passive (relaxation-exhalation) values of elastance and resistance can be used as an index of load compensation. We therefore evaluated the effects of duration of anesthesia on respiratory impedance and stabilization by comparing active elastance (E'rs) and flow resistance (R'rs) to their corresponding passive values (Ers, Rrs) at the beginning and end of steady-state breathing in ten young, healthy anesthetized adults undergoing orthopedic surgery (anesthesia approximately 1.5 MAC of a halogenated anesthetic in 60% N2O-40% O2). Occlusion pressure (P0.1) and components of ventilation also were measured. Duration of anesthesia did not correlate with changes in active or passive mechanics or with control of ventilation. Mean Rrs increased by 76% (P less than 0.025), probably due to a decline of atropine effect; however, R'rs increased by only 17%, indicating near-maximum stabilization of flow-resistive properties at the end. Passive elastance increased 6%, whereas E'rs increased 3.8%, indicating essentially constant volume-elastic stabilization throughout. Occlusion pressure increased 20% and VT/TI 22%, probably due to a decline in effects of sedation and neuromuscular blockade. We conclude that after induction of anesthesia, the reserve available to overcome flow resistance (intrinsic plus equipment) diminishes but is not related to duration of anesthesia. The reserve available to overcome elastic properties remains essentially constant throughout anesthesia.

Small airways function in nonsmokers with rheumatoid arthritis

To evaluate the possible relationship between rheumatoid arthritis (RA) and airways dysfunction independent of cigarette smoking, we studied 19 lifetime nonsmokers with RA and 47 healthy nonsmokers. Ten tests of small airways function were administered to the subjects. In addition, diffusing capacity and static lung compliance were measured, and upstream airway conductance at mid-to-low lung volumes was calculated. Mean values were not significantly lower in the RA group than in the control group in any of the tests of small airways function. Three of the 19 (16%) patients with RA versus 15 of the 47 (32%) control subjects had abnormal findings on greater than 2 tests of small airways function (P greater than 0.1). Although mean diffusing capacity and static lung compliance were both within normal limits in each group, the former tended to be lower, while the latter was significantly lower, in the RA subjects. We conclude that airways dysfunction in RA, if present, is probably related to factors other than the underlying disease; if an association between RA and small airways abnormality is present in some patients, its prevalence is too small to have been detected in our sample.

Respiratory mechanics during halothane anesthesia and anesthesia-paralysis in humans

In six spontaneously breathing anesthetized subjects [halothane approximately 1 maximum anesthetic concentration (MAC), 70% N2O-30% O2], we measured flow (V), volume (V), and tracheal pressure (Ptr). With airway occluded at end-inspiration tidal volume (VT), we measured Ptr when the subjects relaxed the respiratory muscles. Dividing relaxed Ptr by VT, total respiratory system elastance (Ers) was obtained. With the subject still relaxed, the occlusion was released to obtain the V-V relationship during the ensuing relaxed expiration. Under these conditions, the expiratory driving pressure is V X Ers, and thus the pressure-flow relationship of the system can be obtained. By subtracting the flow resistance of equipment, the intrinsic respiratory flow resistance (Rrs) is obtained. Similar measurements were repeated during anesthesia-paralysis (succinylcholine). Ers averaged 23.9 +/- 4 (+/- SD) during anesthesia and 21 +/- 1.8 cmH2O X 1(-1) during anesthesia-paralysis. The corresponding values of intrinsic Rrs were 1.6 +/- 0.7 and 1.9 +/- 0.9 cmH2O X 1(-1) X s, respectively. These results indicate that Ers increases substantially during anesthesia, whereas Rrs remains within the normal limits. Muscle paralysis has no significant effect on Ers and Rrs. We also provide the first measurements of inspiratory muscle activity and related negative work during spontaneous expiration in anesthetized humans. These show that 36-74% of the elastic energy stored during inspiration is wasted in terms of negative inspiratory muscle work.

Active inspiratory impedance in halothane-anesthetized humans

We have used the method of Siafakas et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 51: 109-121, 1981) to determine active elastance (E'rs) and flow resistance (R'rs) of the respiratory system in eight spontaneously breathing humans anesthetized with halothane. From measurements of flow (V) and volume (V) during unoccluded inspirations and of tracheal pressure (P0tr) during subsequent inspirations with the airways occluded at end expiration, we were able to compute E'rs and R'rs as slopes and intercepts of the following function: -P0tr/V = R'rs + E'rsV/V. These measurements were repeated during inspirations loaded with a series of linear flow resistances (delta R). Neither E'rs nor R'rs was significantly affected by delta R. On the average E'rs and R'rs were, respectively, 34.4 and 16.7% higher than the corresponding passive elastance and flow resistance of the respiratory system, indicating that during active breathing the internal impedance of the respiratory system increases. This provides an internal mechanism by which passive loads are compensated.

Lung mechanics in sitting and horizontal body positions

We measured lung compliance, pulmonary flow-resistance, and expiratory reserve volume (ERV) in ten healthy young adults in sitting, supine, and lateral positions. Average lung compliance was 0.21 in sitting, 0.19 in lateral and 0.16 L.cm H2O-1 in supine positions. The change was significant (p less than 0.01) between sitting and supine position. Flow-resistance increased from 1.78 in sitting to 2.5 cm H2O.L-1.s (p less than 0.001) in lateral positions, and did not increase further in the supine posture in spite of a 35 percent decrease in ERV (p less than 0.001). Since it is known that lower airways resistance increases with decreasing lung volume, the lack of change in flow-resistance when shifting from lateral to supine posture suggests that upper airways flow-resistance (larynx and oropharynx) is greater in the lateral decubitus than in the supine positions. The decrease of lung compliance in horizontal postures probably reflects increased pulmonary blood volume and small airways closure.

A simple method for assessing the validity of the esophageal balloon technique

The validity of the conventional esophageal balloon technique as a measure of pleural pressure was tested in 10 subjects in sitting, supine, and lateral positions by occluding the airways at end-expiration and measuring the ratio of changes in esophageal (delta Pes) and mouth pressure (delta Pm) during the ensuing spontaneous occluded inspiratory efforts. Similar measurements were also made during static Mueller maneuvers. In both tests, delta Pes/delta Pm values were close to unity in sitting and lateral positions, whereas in the supine position, substantial deviations from unity were found in some instances. However, by repositioning the balloon to different levels in the esophagus, even in these instances a locus could be found where the delta Pes/delta Pm ratio was close to unity. No appreciable phase difference between delta Pes and delta Pm was found. We conclude that by positioning the balloon according to the "occlusion test" procedure, valid measurements of pleural pressure can be obtained in all the tested body positions.

Hypercalcemia, pneumothorax and pneumoperitoneum in a patient with pulmonary mycobacteriosis and esophageal carcinoma

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Acute respiratory failure and pulmonary arteritis without parenchymal involvement: demonstration in a patient with rheumatoid arthritis

A 28-year-old woman with a eight-year history of rheumatoid arthritis presented with a three-day history of dyspnea. Physical and electrocardiographic findings were consistent with pulmonary hypertension. Arterial blood gases revealed a ventilation-perfusion mismatch. Chest roentgenogram was normal. After transient improvement, she suddenly deteriorated and died. At autopsy, a necrotizing pulmonary panarteritis was found without parenchymal involvement by rheumatoid disease. The pulmonary arteries were the only vessels affected. Immunofluorescent staining revealed immunoproteins scattered throughout the vessel walls without localization to the basement membrane. The unique features of the case are discussed in relation to pulmonary hypertension and rheumatoid lung disease in which vascular lesions are usually associated with honeycomb lung. The association between the rheumatoid arthritis and pulmonary vasculitis was probably coincidental.

The spectrum of extrapulmonary tuberculosis

The incidence of new cases of extrapulmonary tuberculosis has remained constant, despite the decline in new cases of active pulmonary tuberculosis. This might be due to a delay in recognition, and particularly a lack of consideration of tuberculosis when the presenting symptoms are other than respiratory. Extrapulmonary tuberculosis should be considered in the differential diagnosis of bone, joint, genitourinary tract and central nervous system (CNS) diseases. To determine factors that might delay recognition and identification, 62 patients having extrapulmonary tuberculosis during 1969-1972 at the Los Angeles County-University of Southern California Medical Center were studied.Three quarters of these patients had had CNS, skeletal or genitourinary tuberculosis in equal distribution or 25 percent each. CNS involvement was seen frequently in the disseminated form. Presenting symptoms were protean and not specific, such as fever, anorexia, weight loss, cough, lymphadenopathy and neurologic abnormalities. Roentgenograms of the chest were abnormal in most. When a roentgenogram of the chest suggests pulmonary tuberculosis, signs and symptoms in other body systems should suggest extrapulmonary tuberculosis. If no abnormalities are seen on a roentgenogram of the chest, however, this does not preclude the diagnosis of extrapulmonary tuberculosis. Neither does a negative tuberculin skin test exclude the condition. Abnormal laboratory findings are common, especially in disseminated tuberculosis. These include various anemias, bone marrow disorders, hyponatremia due to inappropriate antidiuretic hormone syndrome. Analyses of pleural, peritoneal, pericardial and joint fluid usually show an exudate high in lymphocytes and occasionally low in glucose. Similar findings are seen in spinal fluid. The histological features of caseous or noncaseous granulomas are suggestive of but not specific for tuberculosis. Only culture of mycobacteria from sputum, urine, spinal fluid, pleural and other effusions and tissue biopsy specimens will yield a definitive diagnosis. Physicians must have a high index of suspicion to diagnose extrapulmonary tuberculosis, as it can resemble any disease in any organ system. Immediate therapy in the disseminated variety, sometimes even before a definite diagnosis can be made, may be lifesaving.

Pneumopericardium and pneumothorax complicating bronchogenic carcinoma

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Adenoid cystic carcinoma (cylindroma) of the trachea masquerading as asthma

A 40-year-old woman was admitted with upper airway obstruction; chest roentgenogram with tomograms, laryngoscopy, and bronchoscopy verified the presence of a subglottic tumor. Spirometry disclosed a maximum inspiratory flow rate more reduced than in the maximum expiratory flow rate, suggestive of upper airway obstruction. The pathologic conditions were consistent with cystic adenoid carcinoma (cylindroma) of the trachea. The patient underwent tracheostomy and total laryngectomy with an uneventful recovery. No evidence of local extension or distant metastases were evident at time of surgery.