Idiopathic diaphragmatic paralysis: Bell's palsy of the diaphragm?

STUDY OBJECTIVES: Idiopathic diaphragm paralysis is probably more common and responsible for more morbidity than generally appreciated. Bell's palsy, or idiopathic paralysis of the seventh cranial nerve, may be seen as an analogous condition. The roles of zoster sine herpete and herpes simplex have increasingly been recognized in Bell's palsy, and there are some data to suggest that antiviral therapy is a useful adjunct to steroid therapy. Thus, we postulated that antiviral therapy might have a positive impact on the course of acute idiopathic diaphragm paralysis which is likely related to viral infection. METHODS: Three consecutive patients with subacute onset of symptomatic idiopathic hemidiaphragm paralysis were empirically treated with valacyclovir, 1,000 mg twice daily for 1 week. Prior to therapy, diaphragmatic function was assessed via pulmonary function testing and two-dimensional B-mode ultrasound, with testing repeated 1 month later. Diaphragmatic function pre- and post-treatment was compared to that of a historical control group of 16 untreated patients. RESULTS: All three subjects demonstrated ultrasound recovery of diaphragm function 4-6 weeks following treatment with valacyclovir. This recovery was accompanied by improvements in maximum inspiratory pressure (PI(max)) and vital capacity (VC). In contrast, in the untreated cohort, diaphragm recovery occurred in only 11 subjects, taking an average of 14.9 +/- 6.1 months (mean +/- SD). CONCLUSIONS: The results of this small, preliminary study suggest that antiviral therapy with valacyclovir may be helpful in the treatment of idiopathic diaphragm paralysis induced by a viral infection.

Medical professionalism in the new millennium: are there intercultural differences? Brief report and commentary.

We hypothesized that differences in premedical and medical indoctrination might lead to demonstrable differences in notions of medical professionalism among U.S. medical schoolgraduates (USMG) and international medical graduates (IMG). We used the previously validated Barry Challenges to Professionalism questionnaire to query applicants to our Medicine residency. Two hundred sixty-six of 1,476 applicants responded; 57 were USMG and 188 IMG were non-U.S. citizens. There were no significant differences in responses based on gender or medical school background (comparing USMG vs IMG). Graduates of U.S. and Canadian schools were more likely than those of Indian schools to answer correctly three of 10 questions. We use the results of this ostensibly "negative" study to comment on the foundations for the hypothesis and logistic difficulty of studying the question.

Monitoring recovery from diaphragm paralysis with ultrasound.

BACKGROUND: Diaphragmatic paralysis is an uncommon, yet underdiagnosed cause of dyspnea. Data regarding the time course and potential for recovery has come from a few small case series. The methods that have been traditionally employed to diagnose diaphragmatic weakness or paralysis are either invasive or limited in sensitivity and specificity. A new technique utilizing two-dimensional, B-mode ultrasound (US) measurements of diaphragm muscle thickening during inspiration (Deltatdi%) has been validated in the diagnosis of diaphragm paralysis (DP). The purpose of this study was to assess whether serial US evaluation might be utilized to monitor the potential recovery of diaphragm function. METHODS: Twenty-one consecutive patients with clinically suspected DP were referred to the pulmonary physiology laboratory. Sixteen patients were found to have DP by US (unilateral, 10 patients; bilateral, 6 patients). Subjects were followed up for up to 60 months. On initial and subsequent visits, Deltatdi% was measured by US. Additional measurements included upright and supine vital capacity (VC), maximal inspiratory pressure (Pimax), and maximal expiratory pressure. RESULTS: Eleven of 16 patients functionally recovered from DP. The mean (+/- SD) recovery time was 14.9 +/- 6.1 months. No diaphragm thickening was noted in those patients who did not recover. Positive correlations were found between improvement in Deltatdi% and interval changes in VC, Pimax, and end-expiratory measurements of diaphragm thickness. CONCLUSIONS: US may be used to assess for potential functional recovery from diaphragm weakness or DP. As in previous series, recovery occurs in a substantial number of individuals, but recovery time may be prolonged.

A simulation-based biodefense and disaster preparedness curriculum for internal medicine residents.

AIMS: Disaster and bioterrorism preparedness is poorly integrated into the curricula of internal medicine residency programs. Given that victims may present to a variety of healthcare venues, including primary care practices, inpatient hospital wards, and intensive care units, we developed a curriculum to address this need. METHODS: The curriculum consisted of four didactic sessions with supplemental readings covering biologic, chemical, and radiologic agents, as well as public health infrastructure. All 30 internal medicine resident participants also underwent a four hour training seminar at a high fidelity human simulation center. Instruction included the use of personal protective equipment (PPE)and participation in simulated scenarios utilizing technologically sophisticated mannequins with monitoring and interactive capability. Sessions were videotaped, reviewed with participants, and followed by self-evaluation and constructive feedback. RESULTS: Compared to a control group of residents who did not undergo training, the participants' level of knowledge was significantly better, with mean objective test scores of 66.8%+/-11.8% SD vs. 50%+/-13.1% SD, p < 0.0001. Although there was a trend toward increasing knowledge with increasing level of training in the control group, this difference was not significant. Subjective preparedness was also significantly better in the intervention group (p < 0.0001). Objective improvements were not maintained after one year. CONCLUSIONS: In this pilot study, a disaster-preparedness curriculum including simulation-based training had a positive effect on residents' knowledge base and ability to respond to disaster. However, this effect had diminished after one year, indicating the need for reinforcement at regular intervals.

An Official American Thoracic Society Workshop Report: Chemical Inhalational Disasters. Biology of Lung Injury, Development of Novel Therapeutics, and Medical Preparedness.

This report is based on the proceedings from the Inhalational Lung Injury Workshop jointly sponsored by the American Thoracic Society (ATS) and the National Institutes of Health (NIH) Countermeasures Against Chemical Threats (CounterACT) program on May 21, 2013, in Philadelphia, Pennsylvania. The CounterACT program facilitates research leading to the development of new and improved medical countermeasures for chemical threat agents. The workshop was initiated by the Terrorism and Inhalational Disasters Section of the Environmental, Occupational, and Population Health Assembly of the ATS. Participants included both domestic and international experts in the field, as well as representatives from U.S. governmental funding agencies. The meeting objectives were to (1) provide a forum to review the evidence supporting current standard medical therapies, (2) present updates on our understanding of the epidemiology and underlying pathophysiology of inhalational lung injuries, (3) discuss innovative investigative approaches to further delineating mechanisms of lung injury and identifying new specific therapeutic targets, (4) present promising novel medical countermeasures, (5) facilitate collaborative research efforts, and (6) identify challenges and future directions in the ongoing development, manufacture, and distribution of effective and specific medical countermeasures. Specific inhalational toxins discussed included irritants/pulmonary toxicants (chlorine gas, bromine, and phosgene), vesicants (sulfur mustard), chemical asphyxiants (cyanide), particulates (World Trade Center dust), and respirable nerve agents.

Respiratory muscle strength in the physically active elderly.

Advancing age is associated with a decline in the strength of the skeletal muscles, including those of respiration. Respiratory muscles can be strengthened with nonrespiratory activities. We therefore hypothesized that regular exercise in the elderly would attenuate this age-related decline in respiratory muscle strength. Twenty-four healthy subjects older than 65 years were recruited (11 males and 13 females). A comprehensive physical activity survey was administered, and subjects were categorized as active (n = 12) or inactive (n = 12). Each subject underwent testing of maximum inspiratory and expiratory pressures (PI(max) and PE(max)). Diaphragmatic thickness (tdi) was measured via two-dimensional B-mode ultrasound. There were no significant differences between the active and inactive groups with respect to age (75 vs. 73 years) or body weight (69.1vs. 69.9 kg). There were more women (9) than men (3) in the inactive group. Diaphragm thickness was greater in the active group (0.31 +/- 0.06 cm vs. 0.25 +/- 0.04 cm; p = 0.011). PE(max) and PI(max) were also greater in the active group (130 +/- 44 cm H(2)O vs. 80 +/- 24 cm H(2)O; p = 0.002; and 99 +/- 32 cm H(2)O vs. 75 +/- 14 cm H(2)O; p = 0.03). There was a positive association between PI(max )and tdi (r = 0.43, p = 0.03). Regular exercise was positively associated with diaphragm muscle thickness in this cohort. As PE(max) was higher in the active group, we postulate that recruitment of the diaphragm and abdominal muscles during nonrespiratory activities may be the source of this training effect.

Principles of pulmonary artery catheterization in the critically ill.

The pulmonary artery catheter (PAC) may be helpful in determining the etiology of shock, lactic acidosis, pulmonary edema, oliguric renal failure, pulmonary hypertension, and a number of cardiac abnormalities. In addition, it may also be useful in guiding fluid and vasoactive therapy. However, although hemodynamic data from the pulmonary artery catheter (PAC) is widely used diagnostically and therapeutically in the care of critically ill patients, the use of the catheter has not been shown to provide outcomes benefit. In fact, there is some evidence to suggest that placement of the PAC may actually be detrimental. The reasons for this are unclear, but it has been shown that both physicians and nurses frequently misinterpret waveforms and other data obtained from the PAC. Presently, there are a number of ongoing randomized, controlled trials investigating the use of the PAC in specific clinical situations and/or patient populations as well as using specific treatment strategies. In the meantime, if any benefit is to be achieved, it is imperative that clinicians have a thorough understanding of the indications, contraindications, complications, and pitfalls of data interpretation prior to using the catheter. These are reviewed in this article.