This document provides an update to the European Respiratory Society (ERS)/American Thoracic Society (ATS) technical standards for single-breath carbon monoxide uptake in the lung that was last updated in 2005. Although both D (diffusing capacity) and T (transfer factor) are valid terms to describe the uptake of carbon monoxide in the lung, the term D is used in this document. A joint taskforce appointed by the ERS and ATS reviewed the recent literature on the measurement of D and surveyed the current technical capabilities of instrumentation being manufactured around the world. The recommendations in this document represent the consensus of the taskforce members in regard to the evidence available for various aspects of D measurement. Furthermore, it reflects the expert opinion of the taskforce members on areas in which peer-reviewed evidence was either not available or was incomplete. The major changes in these technical standards relate to D measurement with systems using rapidly responding gas analysers for carbon monoxide and the tracer gas, which are now the most common type of D instrumentation being manufactured. Technical improvements and the increased capability afforded by these new systems permit enhanced measurement of D and the opportunity to include other optional measures of lung function.

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The study of carbon dioxide (CO2) inhalation in psychiatry has a long and varied history, with recent interest in using inhaled CO2 as an experimental tool to explore the neurobiology and treatment of panic disorder. As a consequence, many studies have examined the panic-like response to the gas either using the single or double breath 35% CO2 inhalation or 5-7% CO2 inhaled for 15-20 min, or rebreathing 5% CO2 for a shorter time. However, this lower dose regime produces little physiological or psychological effects in normal volunteers. For this reason we have studied the effects of a higher concentration of CO2, 7.5%, given over 20 min. Twenty healthy volunteers were recruited to a double blind, placebo-controlled study where air and 7.5% CO2 were inhaled for 20 min. Cardiovascular measures and subjective ratings were obtained. When compared to air, inhaling 7.5% CO2 for 20 min increases systolic blood pressure and heart rate, indicating increased autonomic arousal. It also increases ratings of anxiety and fear and other subjective symptoms associated with an anxiety state. The inhalation of 7.5% CO2 for 20 min is safe for use in healthy volunteers and produces robust subjective and objective effects. It seems promising as an anxiety provocation test that could be beneficial in the study of the effects of anxiety on sustained performance, the discovery of novel anxiolytic agents, and the study of brain circuits and mechanisms of anxiety.

Sleep disturbance is common in patients with advanced cancer, and their family carers also may suffer from sleep problems. The aims of this study were to determine the prevalence of sleep-wake disturbances in patients with advanced cancer and their carers, to monitor the amount of daytime spent in activity and rest, and to examine the relationship between sleep, physical, and psychological symptoms. This was a prospective, descriptive observational study in patients with advanced incurable cancer and their carers attending a regional cancer center, using subjective (Short Form-36, Epworth Sleepiness Score, Hospital Anxiety and Depression Scale, Memorial Symptom Assessment Scale, and sleep history and diary) and objective (Actiwatch) assessments over a seven-day period. Sixty patients with advanced cancer and their family carers completed the study. Poor sleep was a frequent complaint: 47% of the patients and 42% of the carers reported that they did not sleep well, yet patients reported sleeping an average of 8.2 hours and carers 7.8 hours per night. The objective assessments revealed that although sleep efficiency (SE) was greater than 90% for most patients and carers, sleep fragmentation was high in both groups. Patients and carers who complained of poor sleep were significantly more anxious (P<0.001 and <0.05) compared with patients and carers who reported sleeping well. Patients who complained of poor sleep had significantly more pain (P<0.05). These results show that a substantial proportion of advanced cancer patients and their carers complained of poor sleep despite reporting "normal" duration of sleep. Objective measurements using Actiwatch revealed good SE but high levels of sleep fragmentation and movement, suggesting that sleep quality may be disturbed. Further work is required to investigate sleep quality and the consequences of poor sleep. In the meantime, health care professionals need to routinely inquire about sleep and consider possible reversible underlying factors, such as pain and anxiety, for those who report sleep disturbance.

Acute hypercapnia was studied to assess its potential as a noninvasive and simple test for evoking neuroendocrine, cardiovascular and psychological responses to stress in man. A single breath of four concentrations of carbon dioxide (CO(2)), 5%, 25%, 35% and 50%, was administered to nine healthy volunteers in a randomized, single-blind fashion. Although no adverse effects occurred, most subjects were unable to take a full inspired vital capacity breath of 50% CO(2). In response to the remaining exposures, subjective and somatic symptoms of anxiety increased in a dose-dependent manner. Unlike 5% and 25% CO(2), 35% CO(2) stimulated significant adrenocorticotropic hormone and noradrenaline release at 2 min and cortisol and prolactin release at 15 min following inhalation. This same dose also provoked a significant bradycardia that was followed by an acute pressor response. No significant habituation of psychological, hypothalamic-pituitary-adrenal (HPA) or cardiovascular responses following 35% CO(2) was seen when this dose was repeated after 1 week. A single breath of 35% CO(2) safely and reliably produced sympathetic and HPA axis activation and should prove a useful addition to currently available laboratory tests of the human stress response.