Richard M. Schwartzstein

An Official American Thoracic Society Statement: Update on the Mechanisms, Assessment, and Management of Dyspnea

BACKGROUND Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome. PURPOSE The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea. METHODS An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members. RESULTS Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains. CONCLUSIONS Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.

Pathophysiology of dyspnea

Dyspnea may be defined as an uncomfortable sensation of breathing. The sense of respiratory effort, chemoreceptor stimulation, mechanical stimuli arising in lung and chest wall receptors, and neuroventilatory dissociation may all contribute to the sensation of dyspnea. Different mechanisms likely give rise to qualitatively different sensations of dyspnea. In most patients, dyspnea is probably due to a combination of mechanisms. For example, in asthma, a heightened sense of effort, neuroventilatory dissociation, and vagal stimuli arising from bronchoconstriction and airway inflammation may all play a role. Patients with different disorders and different mechanisms of dyspnea use different phrases to describe their breathing discomfort. Hence, the language patients use to describe their dyspnea may provide clues to the etiology of their symptoms.

The Affective Dimension of Laboratory Dyspnea Air Hunger Is More Unpleasant than Work/Effort

RATIONALE It is hypothesized that the affective dimension of dyspnea (unpleasantness, emotional response) is not strictly dependent on the intensity of dyspnea. OBJECTIVES We tested the hypothesis that the ratio of immediate unpleasantness (A(1)) to sensory intensity (SI) varies depending on the type of dyspnea. METHODS Twelve healthy subjects experienced three stimuli: stimulus 1: maximal eucapnic voluntary hyperpnea against inspiratory resistance, requiring 15 times the work of resting breathing; stimulus 2: Pet(CO(2)) 6.1 mm Hg above resting with ventilation restricted to less than spontaneous breathing; stimulus 3: Pet(CO(2)) 7.7 mm Hg above resting with ventilation further restricted. After each trial, subjects rated SI, A(1), and qualities of dyspnea on the Multidimensional Dyspnea Profile (MDP), a comprehensive instrument tested here for the first time. MEASUREMENTS AND MAIN RESULTS Stimulus 1 was always limited by subjects failing to meet a higher ventilation target; none signaled severe discomfort. This evoked work and effort sensations, with relatively low unpleasantness (mean A(1)/SI = 0.64). Stimulus 2, titrated to produce dyspnea ratings similar to those subjects gave during stimulus 1, evoked air hunger and produced significantly greater unpleasantness (mean A(1)/SI = 0.95). Stimulus 3, increased until air hunger was intolerable, evoked the highest intensity and unpleasantness ratings and high unpleasantness ratio (mean A(1)/SI = 1.09). When asked which they would prefer to repeat, all subjects chose stimulus 1. CONCLUSIONS (1) Maximal respiratory work is less unpleasant than moderately intense air hunger in this brief test; (2) unpleasantness of dyspnea can vary independently from perceived intensity, consistent with the prevailing model of pain; (3) separate dimensions of dyspnea can be measured with the MDP.

Twelve tips for facilitating Millennials’ learning

Background: The current, so-called “Millennial” generation of learners is frequently characterized as having deep understanding of, and appreciation for, technology and social connectedness. This generation of learners has also been molded by a unique set of cultural influences that are essential for medical educators to consider in all aspects of their teaching, including curriculum design, student assessment, and interactions between faculty and learners. Aim: The following tips outline an approach to facilitating learning of our current generation of medical trainees. Method: The method is based on the available literature and the authors’ experiences with Millennial Learners in medical training. Results: The 12 tips provide detailed approaches and specific strategies for understanding and engaging Millennial Learners and enhancing their learning. Conclusion: With an increased understanding of the characteristics of the current generation of medical trainees, faculty will be better able to facilitate learning and optimize interactions with Millennial Learners.

Longitudinal pedagogy: a successful response to the fragmentation of the third-year medical student clerkship experience.

A longitudinal clerkship was designed at Harvard Medical School (HMS) in 2004–2005 to emphasize continuity, empathy, learner-centeredness, and patient-centered care. In 2005–2006, the curriculum was piloted with eight students who voluntarily enrolled in the third-year curriculum, which focused on longitudinal mentorship and feedback, interdisciplinary care, integration of clinical and basic science, and humanism in patient care. Eighteen traditional curriculum (TC) students at HMS who were comparable at baseline served as a comparison group. SHELF exams and OSCE performance, monthly and end-of-year surveys, and focus groups provided comparisons between pilot and TC students on their performance, perceptions, attitudes, and satisfaction. Pilot students performed as well as or better than their peers in standardized measures of clinical aptitude. They demonstrated statistically significant greater preservation of patient-centered attitudes compared with declining values for TC students. Pilot students rated the atmosphere of learning, effective integration of basic and clinical sciences, mentorship, feedback, clerkship satisfaction, and end-of-year patient-care preparedness significantly higher than TC students. The authors conclude that implementation of a longitudinal third-year curriculum, with only modest alterations in existing clinical training frameworks, is feasible and effective in meeting its stated goals. “Exposing” the hidden curriculum through specific longitudinal activities may prevent degradation of student attitudes about patient-centered care. Minimizing the disjointed nature of clinical training during a critical time in students’ training by providing a cohesive longitudinal curriculum in parallel to clinical clerkships, led by faculty with consistent contact with students, can have positive effects on both professional performance and satisfaction.

Multidimensional Dyspnea Profile: an instrument for clinical and laboratory research

There is growing awareness that dyspnoea, like pain, is a multidimensional experience, but measurement instruments have not kept pace. The Multidimensional Dyspnea Profile (MDP) assesses overall breathing discomfort, sensory qualities, and emotional responses in laboratory and clinical settings. Here we provide the MDP, review published evidence regarding its measurement properties and discuss its use and interpretation. The MDP assesses dyspnoea during a specific time or a particular activity (focus period) and is designed to examine individual items that are theoretically aligned with separate mechanisms. In contrast, other multidimensional dyspnoea scales assess recalled recent dyspnoea over a period of days using aggregate scores. Previous psychophysical and psychometric studies using the MDP show that: 1) subjects exposed to different laboratory stimuli could discriminate between air hunger and work/effort sensation, and found air hunger more unpleasant; 2) the MDP immediate unpleasantness scale (A1) was convergent with common dyspnoea scales; 3) in emergency department patients, two domains were distinguished (immediate perception, emotional response); 4) test–retest reliability over hours was high; 5) the instrument responded to opioid treatment of experimental dyspnoea and to clinical improvement; 6) convergent validity with common instruments was good; and 7) items responded differently from one another as predicted for multiple dimensions. The Multidimensional Dyspnea Profile provides a unified, reliable instrument for both clinical and laboratory research http://ow.ly/Ix8ic

What Can Medical Education Learn From the Neurobiology of Learning

The last several decades have seen a large increase in knowledge of the underlying biological mechanisms that serve learning and memory. The insights gleaned from neurobiological and cognitive neuroscientific experimentation in humans and in animal models have identified many of the processes at the molecular, cellular, and systems levels that occur during learning and the formation, storage, and recall of memories. Moreover, with the advent of noninvasive technologies to monitor patterns of neural activity during various forms of human cognition, the efficacy of different strategies for effective teaching can be compared. Considerable insight has also been developed as to how to most effectively engage these processes to facilitate learning, retention, recall, and effective use and application of the learned information. However, this knowledge has not systematically found its way into the medical education process. Thus, there are considerable opportunities for the integration of current knowledge about the biology of learning with educational strategies and curricular design. By teaching medical students in ways that use this knowledge, there is an opportunity to make medical education easier and more effective. The authors present 10 key aspects of learning that they believe can be incorporated into effective teaching paradigms in multiple ways. They also present recommendations for applying the current knowledge of the neurobiology of learning throughout the medical education continuum.

Procedural Competence in Internal Medicine Residents: Validity of a Central Venous Catheter Insertion Assessment Instrument

Purpose Despite mandates from accreditation bodies for programs to ensure procedural competence, standardized measures do not exist to assess residents’ skills in performing central venous catheter (CVC) insertion. The objective of the present study was to develop an instrument to assess residents in subclavian (SC) CVC insertion, to set performance standards, and to validate the tool using performance data. Method In 2007, the authors convened experts to create an assessment tool for CVC insertion using a modified Delphi method. They applied the Angoff method to a second set of experts to determine minimum passing scores (MPSs) for both the borderline trainee and the competent trainee. Two faculty evaluators then used the checklist to assess residents performing CVCs on simulators. Results The authors created and experts confirmed a 24-item checklist. Using the Angoff method, the MPS required completion of 10 major and 2 minor criteria for a trainee to show borderline proficiency with CVC insertion under supervision. This MPS was correlated with a global rating of 2 on a 5-point scale. The MPS for competence was 17 major and 5 minor criteria. None of the residents deemed competent on a global rating scale achieved the MPS for competence. Conclusions The authors were able to create and validate a consensus-driven procedural assessment tool with data-driven standards for basic proficiency and competence that faculty can use to assess residents as they perform CVC insertion.

Simulation training and its effect on long-term resident performance in central venous catheterization

Introduction: Simulation is a safe alternative to practicing procedural skills on patients. However, few published studies have examined the long-term effect of simulation technology on bedside procedures such as central venous catheter (CVC) insertion. Methods: To determine whether simulation-based teaching improves procedural comfort, performance, and clinical events in CVC insertion, over traditional methods of procedural teaching, and to assess the long-term effect of this training, we conducted a prospective, randomized controlled trial with 53 postgraduate year-1 and postgraduate year-2 medical residents at a tertiary-care teaching hospital. At the start of the study, we assessed all residents’ procedural comfort and previous training and experience with CVCs. We then measured their baseline performance in placing CVCs on simulators, using a validated assessment tool (pretest). For the intervention group, we reassessed performance immediately after simulation training (posttest). All subjects then placed actual CVCs as clinically indicated while on their medical intensive care unit rotations, under the supervision of critical care faculty. We measured clinical events associated with these CVCs. After their medical intensive care unit rotations, we reassessed CVC insertion skills on simulators and procedural comfort of all subjects (delayed posttest). Results: Intervention subjects demonstrated a significant improvement in skills immediately after simulation training. At delayed posttesting, performance diminished somewhat in the intervention subjects and was not significantly different from control subjects; however, a significant increase over pretest scores persisted in both groups. Conclusions: A CVC insertion simulation course improves procedural skills. These skills decline over time, and simulation conferred no long-term additional benefit over traditional methods of procedural teaching.

Dyspnea: A sensory experience

Dyspnea—an unpleasant or uncomfortable awareness of breathing or need to breathe—is a common symptom of patients with cardiopulmonary disease. Although often thought of as a single symptom, dyspnea probably subsumes many sensations. Experimental conditions used to induce dyspnea are characterized by discrete groups or clusters of descriptive phrases. Similarly, as the language of dyspnea is refined further, different disease states may be distinguishable by the nuances of breathlessness described by patients. Evidence is gathering that the sensations of dyspnea are modified by information from a variety of receptors throughout the respiratory system. The sense of effort, although still important in the breathlessness associated with mechanical loads, is insufficient to explain the dyspnea arising from a number of experimental and clinical conditions. As our understanding of the interactions between effort and afferent information from the respiratory system grows, new therapeutic interventions to alleviate dyspnea are likely to follow.