Multiple dimensions of cardiopulmonary dyspnea.

Background: The current theory of dyspnea perception presumes a multidimensional conception of dyspnea. However, its validity in patients with cardiopulmonary dyspnea has not been investigated.

Methods: A respiratory symptom checklist incorporating spontaneously reported descriptors of sensory experiences of breathing discomfort, affective aspects, and behavioral items was administered to 396 patients with asthma, chronic obstructive pulmonary disease (COPD), diffuse parenchymal lung disease, pulmonary vascular disease, chronic heart failure, and medically unexplained dyspnea.

Breathlessness rating type influences respiratory behavior during hypercapnia in the rebreathing test.

Objective: The online rating of perceived breathlessness in a rebreathing test (RT) is a new and powerful technique to analyze the psychological and physiological process related to the mechanisms of breathlessness. The aim of the present study was to assess the influence of rating type on respiratory sensation and behavior during repeated hypercapnic exposures.

Methods: Sixty-one healthy women performed three rebreathing trials.

The language of medically unexplained dyspnea.

Background: Medically unexplained dyspnea (MUD) refers to a condition characterized by a sensation of dyspnea and is typically applied to patients presenting with anxiety and hyperventilation without cardiopulmonary explanations for their dyspnea. The diagnosis is difficult. We investigated whether descriptors of dyspnea and associated symptoms of MUD are differentially diagnostic.

Fearful imagery induces hyperventilation and dyspnea in medically unexplained dyspnea.

Background: Medically unexplained dyspnea refers to a condition characterized by a sensation of dyspnea and is typically applied to patients presenting with anxiety and hyperventilation without underlying cardiopulmonary pathology. We were interested to know how anxiety triggers hyperventilation and elicits subjective symptoms in those patients. Using an imagery paradigm, we investigated the role of fearful imagery in provoking hyperventilation and in eliciting symptoms, specifically dyspnea.

Repeated experiences of air hunger and ventilatory behavior in response to hypercapnia in the standardized rebreathing test: effects of anxiety.

In this study, we assessed air hunger (AH) and ventilatory responses to repeated CO(2) exposures in healthy women (N=31), scoring high or low for trait anxiety. A standardized rebreathing test, implying a gradually increasing CO(2) stimulus, was administered three times with 15-min intervals. Respiratory behavior and the intensity of AH perception were measured continuously.

Anxiety and respiratory variability.

Associations of inter- and intra-individual differences in anxiety and fear with within subject variability in breathing parameters were explored. Timing and volume components of respiration and FETCO(2) were measured non-intrusively before and during anxious and fearful imagery in 98 young women. Trait anxiety was associated with less variability in several breathing parameters during baseline preceding imagery.

US-inflation in a differential odor-conditioning paradigm is not robust: relevance for medically unexplained symptoms.

Reported somatic symptoms without clear relation to physiological processes are studied. A learning paradigm was used with two odors (CSs) and the inhalation of CO(2)-enriched air (US), while measuring symptom levels and respiratory behavior. After paring one odor with the CO(2)-enriched air and the other odor with air, half of the participants received a US-inflation manipulation (information manipulation and enhanced US).

Air hunger and ventilation in response to hypercapnia: effects of repetition and anxiety.

We investigated the effects of anxiety on the intensity of air hunger during gradually increasing levels of CO2 until the end-tidal fractional concentration of CO2 was 7.9% or air hunger was intolerable. Normal high and low (trait) anxious participants (N=23) went through three rebreathing trials (15 min interval).

Acquired lightheadedness in response to odors after hyperventilation.

Objective: This study aimed to investigate whether lightheadedness in response to odors could be acquired through previous associations with hyperventilation-induced hypocapnia.

Methods: Diluted ammonia and acetic acid served as conditional odor cues (CSs) in a differential associative learning paradigm. Hyperventilation-induced hypocapnia (unconditional stimulus [US]) was used to induce lightheadedness.

Imagined risk of suffocation as a trigger for hyperventilation.

Objective: Although hyperventilation has been hypothesized to play a role in many pathologies, its critical triggers remain poorly understood. The present experiment aimed to test whether stronger hyperventilation responses occur in response to suggested risk of suffocation compared with other fearful situations in high- and low-trait anxious women.

Methods: Fractional end-tidal CO2-concentration (FetCO2), respiratory frequency, and inspiratory volume were measured nonintrusively in high- (n = 24) and low- (n = 24) trait anxious women during imagery of 3 fear, 1 tension, 1 depressive, and 3 relaxation scripts.

Respiratory complaints in Chinese: cultural and diagnostic specificities.

Study Objectives: We investigated the qualitative components of a wide range of Chinese descriptors of dyspnea and associated symptoms, and their relevance for clinical diagnosis.

Measurements: Sixty-one spontaneously reported descriptors were elicited in Chinese patients to make a symptom checklist, which was administered to new groups of patients with different cardiopulmonary diseases, to patients with medically unexplained dyspnea and to healthy subjects.

Results: Test-retest reliability was satisfactory for most of the descriptors.

Perceived relation between odors and a negative event determines learning of symptoms in response to chemicals.

Background: We investigated the effects of worrying information about chemical pollution on subjective symptoms in response to an odor that was previously associated with symptom episodes.

Methods: Ammonia and butyric acid in harmless concentrations were used as odor cues, and 10% CO2-enriched air was used to induce symptoms. One of two odors was consistently mixed with CO2-enriched air while the other odor was presented in room air during 80 s breathing trials (three trials of each).

Resting end-tidal CO2 and negative affectivity.

Objective: Dhokalia, Parsons, and Anderson (Psychosom Med 1998;60:33-37) found a positive correlation between a trait measure of negative affectivity (NA; neuroticism) and resting end-tidal fractional concentration of CO2 (FetCO2) (fractional-concentration of end-tidal carbon dioxide) in a nonclinical sample. This contrasts sharply with studies reporting a negative association of FetCO2 with state measures of NA and with studies reporting no or a negative relationship between FetCO2 and trait NA. In two studies we aimed to clarify this paradox.

Media warnings about environmental pollution facilitate the acquisition of symptoms in response to chemical substances.

Objective: Previous studies showed that somatic symptoms can be acquired in response to chemical substances using an associative learning paradigm, but only when the substance was foul smelling and not when it smelled pleasant. In this study, we investigated whether warnings about environmental pollution would facilitate acquiring symptoms, regardless of the pleasantness of the smell.

Method: One group received prior information framing the study in the context of the rapidly increasing chemical pollution of our environment.

Guidelines for mechanical lung function measurements in psychophysiology.

Studies in psychophysiology and behavioral medicine have uncovered associations among psychological processes, behavior, and lung function. However, methodological issues specific to the measurement of mechanical lung function have rarely been discussed. This report presents an overview of the physiology, techniques, and experimental methods of mechanical lung function measurements relevant to this research context.