Functional single ventricle: cardiorespiratory response to exercise.

The cardiorespiratory response to exercise was measured in 27 children with functional single ventricle. All 27 patients had a significant reduction in exercise time, work performed, maximal exercise heart rate, maximal oxygen uptake and systemic arterial blood oxygen saturation. The reduction in exercise performance increased with increasing age of the patients. All patients ventilated excessively at rest and during exercise. This study documented the precise level of exercise intolerance in patients with functional single ventricle. The progressive deterioration in exercise performance with increasing patient age may lend credence to the concept that operation for physiologic correction of functional single ventricle should be considered during or before adolescence.

Exercise tolerance and cardiorespiratory response to exercise after the Fontan operation for tricuspid atresia or functional single ventricle.

To determine the impact of the Fontan operation on exercise tolerance and on the cardiorespiratory response to exercise, we compared the results of graded exercise to maximal effort of 81 patients with tricuspid atresia or single functional ventricle studied preoperatively with those of 29 patients studied postoperatively. Postoperatively, the values for total work performed, duration of exercise and maximal oxygen uptake increased significantly. Regardless of operative status, the maximal heart rate during exercise was reduced. The cardiac output and stroke volume response to exercise were subnormal after operation. Systemic arterial blood oxygen saturation was reduced markedly preoperatively both at rest and during exercise; postoperatively, it was significantly greater than the preoperative value but it remained slightly abnormal. The ventilatory response to exercise (respiratory rate, minute ventilation and ventilatory equivalent for oxygen) decreased toward normal after operation. Exercise tolerance and the cardiorespiratory responses to exercise improve after the Fontan operation. Formal exercise testing is essential to quantitate the degree of improvement.

Obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome is the most common cause of hypersomnolence in patients referred to sleep disorders centers. This type of sleep apnea is characterized by loud snoring, nocturnal oxyhemoglobin desaturation, and disrupted sleep that leads to daytime hypersomnolence. The anatomic configuration of the pharynx and the physiologic responses to occlusion of the upper airway play a major role in the pathogenesis of this disorder. Polysomnography can accurately identify obstructive sleep apnea, and the multiple sleep latency test allows an objective measurement of daytime alertness. Weight loss and training the patient to sleep in a lateral position are frequently used to alleviate mild cases. Nasally applied continuous positive airway pressure is an extremely effective modality for treating moderate and severe obstructive sleep apnea. Surgical correction of obvious anatomic defects has a role in diminishing obstructive sleep apnea, but the exact role of surgical intervention in patients without obvious anatomic defects remains unknown. The choice of therapy should be tailored to the individual patient with sleep apnea, and careful follow-up is essential to ensure a positive response to therapy.

Unexplained dyspnea.

Dyspnea is a common symptom that is difficult to define and can result from a wide variety of causes. This complex sensation that arises from multiple stimuli involves both subjective perceptions and objective reactions. In the assessment of patients with dyspnea, use of a systematic approach to determine the precipitating factors and the degree of breathlessness is important. Although many diseases may produce dyspnea, two thirds of the cases result from a pulmonary or cardiac disorder. Neuromuscular and psychogenic causes should also be considered. A comprehensive history, physical examination, and basic laboratory tests are important in the initial assessment; however, the diagnosis may depend on specialized testing, the results of which may differ from the initial clinical impression. Initial testing should include electrocardiography, chest roentgenography, hemoglobin determination, thyroid function, and spirometry with use of a bronchodilator. More specialized evaluation includes detailed pulmonary function testing and echocardiography. As shown in our illustrative case, cardiopulmonary exercise testing is important for evaluation of unexplained dyspnea when initial test results are nondiagnostic. Accurate diagnostic data are critical for choosing appropriate treatment.

"Postpolio" sequelae and sleep-related disordered breathing.

OBJECTIVE: To analyze the clinical manifestations and various types of sleep-related disordered breathing (SRDB) in patients with a history of poliomyelitis and with current "postpolio" sequelae (PPS). MATERIAL AND METHOD: We retrospectively reviewed the medical records of 108 consecutive patients with PPS and sleep disturbances encountered during an 11-year period at Mayo Clinic Rochester and abstracted the features of acute polio, PPS, and results of sleep evaluation (overnight oximetry or polysomnography). Only those patients who were not receiving ventilatory support were included in the study. RESULTS: The features of PPS were dyspnea, fatigue, new weakness, and musculoskeletal pain. Of the 108 patients, 35 fulfilled the inclusion criteria. Sleep evaluations revealed three general types of disturbances: obstructive sleep apnea (group O, N = 19); hypoventilation (group H, N = 7); and both (group OH, N = 9). The mean apnea/hypopnea index was 37, 4, and 16 per hour in patients in groups O, H, and OH, respectively (P < 0.05), and the mean arterial carbon dioxide tension was 39, 60, and 55 mm Hg in these respective study groups (P < 0.05). The overall mean age at onset of symptoms of SRDB was 47 years, and the mean latent period after acute polio was 37 years. Hypersomnolence was the commonest SRDB symptom, present in 32 of the 35 patients. Snoring was noted in 100% of patients in group O, 0% in group H, and 67% in group OH. Patients in group O were obese and had normal lung function. Patients in group H tended to have normal weights and a history of diffuse neurologic deficits involving the trunk during the acute episode of polio. Scoliosis, restricted lung function, cor pulmonale, and decreased maximal respiratory pressures were common in patients in group H. Patients in group OH had overlapping features of those in groups O and H. CONCLUSION: In patients with PPS, we identified three patterns of sleep disturbances--obstructive sleep apnea, hypoventilation, and a combination of both. These groups are characterized by clinical features and by results of arterial blood gas determinations, overnight oximetry, and polysomnography. SRDB is a late sequela of poliomyelitis, and clinical evaluation should include information about sleep.

Cardiorespiratory function in asymptomatic survivors of neonatal respiratory distress syndrome.

We measured cardiopulmonary function at rest and during exercise in 15 healthy survivors of neonatal respiratory distress syndrome (RDS) and compared the results with those in 15 normal subjects. The mean birth weight of the RDS group was 1,771 g, and 12 of the 15 patients had required endotracheal intubation. The oxygen scores ranged from 79 to 3,322. Five of the 15 RDS patients had abnormal results of pulmonary function studies at rest. Peak expiratory flow was lower (P less than 0.05) in the RDS group (2.98 liters/min) than in the control group (3.57 liters/min). A negative correlation was noted between the forced expiratory flow between 25 and 75% of vital capacity and the oxygen score in these patients. Exercise tolerance was below normal in two of the RDS patients, both of whom also had abnormal pulmonary function at rest. One patient in the RDS group had systemic arterial hypertension at rest and during exercise. No significant differences in exercise tolerance or the cardiorespiratory response to exercise were observed between the two groups.

A prospective study of airway reactivity before bone marrow transplantation.

The purposes of this study were to assess baseline airway function and to determine the frequency of airway reactivity in patients before bone marrow transplantation (BMT). The ratio of the forced expiratory volume at 1 second to the forced vital capacity (FEV1/FVC) was the measure of baseline airflow. Using methacholine challenge, we tested 53 patients before conditioning chemotherapy, total-body irradiation, and BMT. All patients had a baseline FEV1/FVC of 70% or more. The mean baseline FEV1/FVC was 84(+)/- 6%. The response to methacholine challenge was defined by the change in FEV1 from baseline (delta FEV1). A positive response (delta FEV1 of 20% or more) occurred in 11 of 53 patients (21%), a borderline response of (delta FV1 of less than 20% but greater than or equal to 10%) was was found in 10 (19%), and no response (Delta FEV1 of less than 10%) was elicited in 32 (60%). In our group of patients with a positive or borderline response to methacholine, we found no significant relationship to baseline FEV1/FVC, smoking history, hematologic diagnosis or study, or major post-BMT pulmonary complications including bronchiolitis obliterans. We concluded that pretransplantation airway reactivity, as measured by methacholine challenge and in the setting of normal baseline FEV1/FVC, was common before BMT. The presence of a borderline or positive response to methacholine challenge before transplantation was not associated with the development of either clinical or pathologically proven posttransplantation bronchiolitis obliterans.

Successful treatment of obstructive sleep apnea with use of nasal continuous positive airway pressure in three patients with mucosal hemangiomas of the oral cavity.

Cysts and benign tumors are uncommon causes of obstructive sleep apnea (OSA), and surgical removal is usually favored. In patients in whom an operation poses a high risk, however, nasal continuous positive airway pressure (CPAP) may prove beneficial. We describe three patients with hemangiomas of the oral cavity in whom polysomnography revealed moderate to severe OSA. In all three patients, nasal CPAP effectively decreased sleep-related disordered breathing events and dramatically improved their sleep. To our knowledge, this is the first report of OSA associated with hemangiomas involving the upper airway. Our experience suggests that nasal CPAP therapy is effective and well tolerated in such patients.

Upper airway obstruction and disordered nocturnal breathing in children.

Fourteen children with disordered breathing during sleep (obstructive apnea, obstructive hypopnea, or snoring) and anatomic obstruction of the upper airway were studied. Twelve children had hypertrophied tonsils and adenoids, and two had a deviated nasal septum. No child had sequelae of severe sleep apnea--that is, cor pulmonale, pulmonary hypertension, or alveolar hypoventilation. Results of polysomnographic studies were abnormal in all and revealed that obstructive hypopnea (increased respiratory effort with decreased airflow) was more common than obstructive apnea (increased respiratory effort without airflow). Surgical removal or correction of the upper airway obstructive lesion in 12 children resulted in normal nocturnal respiration. Surgical intervention was declined in two patients, and their symptoms persist. We conclude that surgical removal of upper airway obstructive lesions in children with disturbed nocturnal sleep should not be reserved only for those with serious sequelae of obstructive sleep apnea; considerable benefit is gained in selected patients with mild obstructive sleep apnea or hypopnea.

Exercise limitation and pulmonary rehabilitation in chronic obstructive pulmonary disease.

Impairment of exercise tolerance is a common problem in patients with severe chronic obstructive pulmonary disease. The cause of exercise intolerance in patients with severe chronic obstructive pulmonary disease is multifactorial and includes impaired lung mechanics, fatigue of inspiratory muscles, impaired gas exchange, right ventricular dysfunction, malnutrition, occult cardiac disease, deconditioning, and psychologic problems; however, impaired lung mechanics and gas exchange abnormalities seem to be the major limiting factors. Recently, the approach to management of pulmonary rehabilitation in patients with chronic obstructive pulmonary disease has changed because improvement in exercise tolerance has been demonstrated after pulmonary rehabilitation. Other adjunctive measures that have been shown to contribute to the observed improvement in exercise tolerance include administration of oxygen, nutritional support, cessation of smoking, and psychosocial support. The roles of ventilatory muscle endurance training, respiratory muscle rest therapy, nasally administered continuous positive airway pressure, and training of the muscles of the upper extremities are less clearly defined.

Effect of resection of the sternum and manubrium in conjunction with muscle transposition on pulmonary function.

We recorded the changes in pulmonary function that occurred after removal of the sternum and manubrium and repair by pectoralis major muscle transposition in six patients. Of these patients, three had osteomyelitis of the manubrium and sternum, two had osteosarcoma of the sternum, and one had osteomyelitis and radionecrosis of the manubrium and sternum. Body plethysmography and the rebreathing, hypercapnic ventilatory response test with inductive plethysmographic recordings of chest-wall motion were performed preoperatively and postoperatively. Preoperatively, four of the six patients had evidence of mild to moderate chest-wall restriction. Pulmonary function was normal in the other two patients. Postoperatively, total lung capacity was unchanged but the vital capacity decreased 11.5% in the overall group. Static compliance, retractive force, and the steady-state diffusing capacity for carbon monoxide decreased modestly but significantly postoperatively. The expiratory flow rates and maximal voluntary ventilation remained unchanged. Preoperatively, the slope of the hypercapnic ventilatory response was less than that predicted. Postoperatively, the slope did not change. In three patients, however, increased dependence on the abdomen for breathing suggested a dynamic restriction of rib-cage motion. On the basis of our findings, we conclude that surgical removal of the sternum and manubrium in conjunction with muscle flap repair is a well-tolerated procedure. Any postoperative changes in pulmonary function are minor.

Long-term clinical experience with transtracheal oxygen catheters.

OBJECTIVE: To evaluate and discuss the use of transtracheal oxygen catheters for the treatment of chronic hypoxemia and to discuss the complications associated with the placement and care of these devices. DESIGN: We conducted a retrospective study at a tertiary medical center and reviewed the pertinent literature. MATERIAL AND METHODS: The medical records of 56 patients who received a transtracheal oxygen catheter between January 1987 and June 1992 at our institution were reviewed for demographic data, diagnosis leading to catheter placement, complications related to catheter use, reason for catheter removal, and duration of use. Follow-up results were established by documentation in the medical records or telephone interview. RESULTS: During the study period, 39 men and 17 women received a transtracheal catheter. More than half the patients (52%) had chronic obstructive pulmonary disease. The duration of use of the catheter ranged from 2 days to more than 6 years, and the most frequent cause for removal of the catheter was death. Of the 56 patients, 42 died with the catheter in place, 24 within the first year after placement. Complications ranged from mucous plugging (38 % of patients) to pneumothorax (4%), and no patient died of a catheter-related complication. Overall, 55% of patients had their catheter for less than 1 year after placement. CONCLUSION: In patients with transtracheal oxygen catheters, problems related to mucous plugging are common, but severe complications such as pneumothorax and pneumomediastinum are uncommon. Although selection factors that would identify ideal candidates for transtracheal oxygen therapy have not been established, such a catheter is best placed in highly motivated patients who can physically manage the daily care of this device.

Carbon monoxide diffusing capacity of the lungs determined by single-breath and steady-state exercise methods.

We measured carbon monoxide diffusing capacity of the lungs (DL,CO) by both the resting single-breath (SB) and steady-state (SS) exercise methods in 95 patients referred for pulmonary function testing. A 10-second breath-holding method was used for the SB test. DL,CO (SS) was measured during the last minute of a 3-minute exercise test on a 9-inch step. Results of the two methods showed good agreement, the SB-SS difference averaging -0.70 (SD, 3.39) ml/min per mm Hg. The difference between the two methods was not correlated with other measurements of pulmonary function except minute ventilation during the exercise performed in the DL,CO (SS) procedure. In a separate study of laboratory personnel, the day-to-day variabilities of the two tests were similar (SD, 1.4 ml/min per mm Hg). Alveolar volume obtained by helium dilution during the SB test was comparable to total lung capacity (TLC) estimated by multiple-breath nitrogen washout in patients without severe airway obstruction. In severe airway obstruction, the mean SB alveolar volume was 13.8% less than the TLC by nitrogen washout, a difference that may be useful as an indicator of inefficiency of gas mixing in the lungs. We conclude that the SB and SS exercise methods provide similar estimates of DL,CO in patients referred to a pulmonary function laboratory.

The lipoprotein profile of chylous and nonchylous pleural effusions.

The lipoprotein electrophoregrams and the cholesterol and triglyceride levels of the pleural fluid were evaluated for patients with chylous pleural effusions, as defined by the presence of a distinctive band of chylomicrons on the lipoprotein electrophoregram, and in patients with nonchylous effusions of various causes. One hundred forty-one patients were studied during a 3-year period. The chylous effusions had strikingly higher triglyceride levels (median 249, range 49 to 2,270 mg/dl) than the nonchylous group (median 33, range 13 to 107 mg/dl); there were no significant differences in cholesterol or protein between the two groups. The gross description of the fluid was a poor indicator of its origin, being described as consistent with chyle in less than 50% of cases of chylous effusions. The triglyceride values distinguished chylous effusion from nonchylous effusion; values greater than 110 mg/dl are highly suggestive of a chylous effusion. Equivocal cases--triglyceride values between 50 and 110 mg/dl--required lipoprotein analysis. Pleural effusions of undetermined cause, regardless of gross appearance of the fluid, require that a screening triglyceride value be obtained to rule out a chylous effusion.

Impaired exercise tolerance after inferior vena caval interruption.

Four patients were evaluated for persistent dyspnea eight months to four years after inferior vena caval interruption for treatment of pulmonary emboli. Maximal exercise testing with gas-exchange analysis was performed. All patients attained less than 64 percent of predicted maximal oxygen uptake. Peak exercise heart rates were 85 percent or greater of predicted values. Arterial hypoxemia was not observed. The ratio of dead space to tidal volume (VD/VT) decreased with exercise, and the ratios of maximal exercise ventilation to maximal voluntary ventilation (VE/MVV) were less than 67 percent. These results suggest a cardiac rather than a ventilatory limitation to exercise. Inadequate venous blood return to the heart is the likely mechanism for the impaired exercise performances.

Pulmonary hypertension, hemolytic anemia, and renal failure. A mitomycin-associated syndrome.

After treatment with mitomycin C, a patient developed pulmonary hypertension with interstitial infiltrates, microangiopathic hemolytic anemia, systemic hypertension, and renal failure with the nephrotic syndrome. Open lung biopsy documented intracapillary fibrin thrombi in the pulmonary vasculature. Renal biopsy documented glomerular and arteriolar changes that were most consistent with a thrombotic-thrombocytopenic-like process. Treatment with corticosteroids, fresh-frozen plasma, and total plasma exchange was ineffective. The patient died six months after the onset. When mitomycin-C therapy is given, the clinician should be aware of the pulmonary, renal, and microangiopathic changes that can be associated with such therapy.

Time course of recovery from frostbitten phrenics after coronary artery bypass graft surgery.

Bilateral diaphragmatic paralysis developed in a patient after coronary artery bypass graft surgery during which cold cardioplegia was used. The patient's progress and eventual recovery over an 18-month period is described, with particular reference to chest wall motion and respiratory pressure measurements.

Exercise cardiorespiratory function in adolescents with pectus excavatum. Observations before and after operation.

We studied 12 children with pectus excavatum (mean age, 13.8 years) using pulmonary function and exercise testing. Eight patients had surgical repair and were studied before and after repair. Four patients did not have repair and were tested twice. The degree of chest wall deformity in the two groups was similar. All patients reached 86% or more of their maximal predicted heart rate with exercise. Total lung capacity decreased 8% (p less than 0.01) after operation. In the nonoperated control group, total lung capacity was similar during both studies. The ratio of ventilation at maximal exercise to maximal voluntary ventilation was 68% +/- 12% before and 66% +/- 9% after operation in the operated group and 69% +/- 18% and 79% +/- 30% at two studies in the nonoperated group (nonsignificant changes). Maximal oxygen uptake was 36.1 +/- 4.4 ml/kg/min preoperatively and 38.1 +/- 8.1 postoperatively and 41.2 +/- 7.3 ml/kg/min and 43.0 +/- 6.9 on two studies in the nonoperated group (nonsignificant changes). Cardiac output and stroke volume increased appropriately with exercise both before and after operation. Operation had no physiologically significant effect on the cardiorespiratory response to exercise. Slight changes in cardiorespiratory function occurred in both operated and nonoperated subjects. These results emphasize the importance of studying patients before and after operation and of using a control group.

Direct and indirect blood pressure during exercise.

In 27 subjects, we compared rest and exercise blood pressure (BP) measurements determined directly by catheterization of the radial artery with simultaneous values obtained indirectly by auscultation of the brachial artery. As work increased, the systolic BP increased, whereas the diastolic BP did not change. Considering all comparisons, direct BP was greater than indirect BP by a mean of 29.0 mm Hg for systolic BP and 12.3 mm Hg for diastolic BP. As exercise level increased, the difference between direct and indirect systolic BP decreased whereas the difference between direct and indirect diastolic BP did not change. Both methods have advantages for assessment of BP response to exercise: normality of BP response is best assessed by auscultation, whereas beat-by-beat trends in BP are more accurately defined by the direct method.

Factitial leg ulcers associated with an unusual sleep disorder.

A 19-year-old woman presented with a 14-month history of multiple, factitially induced, full-thickness leg ulcers. Nocturnal polysomnography with video monitoring revealed a short sleep latency and frequent sleep stage changes. Rapid eye movement sleep was absent. All stages of non-rapid eye movement sleep were associated with leg rubbing. After treatment that included avoidance of daytime naps and administration of chlorpromazine at bedtime, affect, daytime behavior, nocturnal sleep, and the ulcers improved markedly. To our knowledge, there are no reports of factitial dermatosis associated with disordered sleep. Our findings suggest that abnormal sleep may play a role in initiating or perpetuating factitial dermatoses. This case illustrates that polysomnography and video monitoring may be indicated in the evaluation of patients with factitial dermatoses.