Marc H. Lavietes

Natural history of severe chronic fatigue syndrome

OBJECTIVE To evaluate the natural history of chronic fatigue syndrome (CFS) in a severely ill group of patients at three points in time. DESIGN Patients were enrolled from April 1992 to February 1994 and were evaluated three times. Time 1 (at enrollment): history, physical evaluation, and psychiatric evaluation; Time 2 (median = 1.6yrs after initial evaluation): postal questionnaire to assess current condition; Time 3 (median = 1.8 yrs after Time 2): medical and psychiatric evaluations. SETTING The New Jersey CFS Cooperative Research Center, an ambulatory setting. PATIENTS Twenty-three patients fulfilled the 1988 case definition for CFS and had symptom complaints that were substantial or worse in severity. All patients were ill less than 4.5 years; and none had a DSM-III-R psychiatric disorder in the 5 years before illness onset; none had substance abuse in the 10 years before enrollment. MAIN OUTCOME MEASURES Severity of CFS symptoms was assessed by self-report questionnaires, laboratory tests, and medical examination. Psychological status was assessed using the Q-D15 and the Centers for Epidemiological Study-Depression Scale. At each time of evaluation, patients were categorized as severe, slightly improved, improved, and recovered. RESULTS Over the 4 years of the study, 13 patients remained severely ill, 9 improved but still fulfilled the 1994 case definition for CFS, and 1 recovered. Illness duration, mode of onset, psychiatric status or depressed mood at intake, or chemical sensitivity did not predict illness outcome. One patient was diagnosed with an alternate illness, but it probably did not explain her CFS symptoms. Mood improved for those patients whose illness lessened. CONCLUSIONS The prognosis for recovery was extremely poor for the severely ill subset of CFS patients. The majority showed no symptom improvement and only 4% of the patients recovered. Illness severity between Times 2 and 3 remained stable.

Relationship of Static Respiratory Muscle Pressure and Maximum Voluntary Ventilation in Normal Subjects

40 normal subjects performed spirometry, maximum voluntary ventilation (MVV), and tests of static inspiratory (Pi max) and expiratory (Pe max) respiratory muscle pressure. Forced expiratory volumes in 0.5 (FEV0.5), in 0.75 (FEV0.75), and 1 sec (FEV1) correlated significantly with MVV (r = 0.805, 0.804, 0.779, respectively). When Pi max was considered as a second independent variable, the probability of predicting MVV from timed forced expiratory volumes was enhanced (r = 0.914, 0.900 and 0.872 for FEV0.5, FEV0.75, and FEV1, respectively). Statistical analysis indicated that multiple regression with Pi max was superior to regression with timed forced expiratory volume alone in the prediction of MVV. For any given FEV1, however, Pi max was widely dispersed (range: -60 to -200 cm H2O). MVV values, expressed as percentage difference between largest and smallest value, varied less than did Pi max. Pe max, vital capacity, height and age did not enhance the ability of timed forced expiratory volumes to predict MVV. These data indicate that while respiratory muscle strength is important for sustaining maximal ventilation, the MVV is not a sensitive indicator of respiratory muscle strength.

Dyspnea and Symptom Amplification in Asthma

Background: The severity of a patient’s asthma and the intensity with which he describes his dyspnea do not correlate. Objectives: There is an indirect relationship between airway function in asthma and the intensity of dyspnea; this relationship is found only when the measure of a patient’s general tendency to exaggerate the intensity of any somatic symptom is considered simultaneously. Methods: Lung function, including spirometry (forced expiratory volume in 1 s, FEV1) and plethysmography (airway resistance, Raw), dyspnea (Borg scale score) and the tendency to exaggerate (the somatosensory amplification scale score, SSAS) have been quantified in 42 stable asthmatic patients. Results: There was no correlation between the Borg score and any spirometric or plethysmographic measure in these subjects. By contrast, there was a moderate correlation between the Borg score and the SSAS (r = 0.36, p = 0.03). However, when FEV1 or Raw (abscissa) and Borg scores (ordinate) were converted to residuals, there was a moderate correlation between the residuals and the SSAS score (for FEV1, r = 0.33 and p = 0.05; for Raw, r = –0.36 and p = 0.03). Conclusion: A physician may make a reasonable estimate of an asthmatic patient’s lung function from the intensity of his complaint only if he – the physician – considers the patient’s tendency to symptom amplify as well.

Respiratory Muscle Length and Strength in Patients with Chronic Abdominal Distension

Starlings law (the energy of muscle contraction is proportional to the initial fiber length) has been applied to contraction of inspiratory muscles. Its application to the expiratory muscles is difficult because both maximal length and maximal pressure development occur at total lung capacity (TLC). We hypothesize that decrease of both inspiratory (Pimax) and expiratory (Pemax) muscle strength in chronic ascites (CA) will reflect generalized muscle weakness and stretching of both the diaphragm and abdominal wall as well. To test this hypothesis, we evaluated Pimax and diaphragm length (at functional residual capacity) in 22 patients. Pemax, external oblique and transversus abdominus muscle lengths, and anterior abdominal wall muscle thickness were measured at TLC. We found Pimax (78 +/- 19% predicted), Pemax (61 +/- 17%), and--as an index of general muscle strength--handgrip strength (75 +/- 22%) all to be minimally reduced. Respiratory muscle strength did not correlate with any measurement of inspiratory/expiratory muscle length or thickness. With fluid removal, abdominal muscles shortened; diaphragmatic curvature decreased although diaphragm length was unchanged. Nevertheless, neither Pimax nor Pemax increased. Respiratory muscle strength depends upon generalized muscle strength more so than upon muscle length in CA patients.

Right Ventricular Failure in a Patient with Diabetic Neuropathy (Myopathy) and Central Alveolar Hypoventilation

An unusual patient with hypoxemia, hypercapnia, and right ventricular failure is presented. Minimal skeletal muscle weakness, although present, cannot explain hypercapnia. Muscle biopsy revealed diabetic microangiopathy. Carbon dioxide stimulation demonstrated a diminished hypercapnic ventilatory response. The patient benefited from progesterone therapy. In this unusual patient, mild muscular weakness, caused by diabetes, and central alveolar hypoventilation have acted in synergism to cause abnormal ventilation and right ventricular failure.

The Interpretation of Dyspnea in the Patient with Asthma.

Physicians have noted dyspnea in severely ill asthmatic patients to be associated with fright or panic; in more stable patients dyspnea may reflect characteristics including lung function, personality and behavioral traits. This study evaluates the symptom of dyspnea in 32 asthmatic patients twice: first when acutely ill and again after an initial response to therapy. Spirometry was performed, dyspnea quantified (Borg scale), and panic assessed with a specialized measure of acute panic (the acute panic inventory (API)) in the 32 patients before and again after treatment. After treatment, questionnaires to evaluate somatization and panic disorder were also administered. When acutely ill, both the API and all spirometric measures (PEFR; FEV1; IC) correlated with dyspnea. Multiple linear regression showed that measures of the API, the peak expiratory flow rate, and female sex taken together accounted for 41% of dyspnea in acute asthma. After treatment, the API again predicted dyspnea while spirometric data did not. Those subjects who described themselves as having chronic panic disorder reported high grades of dyspnea after treatment also. We conclude that interpretations of the self-report of asthma differ between acutely ill and stable asthmatic patients.