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Biomedical subjects

G Hibbert

Publications and source records attributed to G Hibbert.

9 recordsLinked to original sources
PubMed1989

Hyperventilation: is it a cause of panic attacks?

During transcutaneous PCO2 (PtcCO2) monitoring of 15 freely ambulant patients suffering from panic attacks, all the patients experienced a typical attack. Seven were identified as hyperventilators, as PtcCO2 fell to abnormally low levels during the attack. This group could not be distinguished on the basis of either their usual symptoms of panic or the hyperventilation provocation test. There was no apparent association between absolute levels of PCO2 and the nature of symptoms. The anxiety ratings of hyperventilators were lower than those of non-hyperventilators. These data do not support the hypothesis that hyperventilation causes panic attacks or contributes to their severity. Hyperventilation may be better understood as a consequence of panic.

Adult↗
PubMed1988

Time-dependent variations of transcutaneous PCO2 level in normal subjects.

Transcutaneous PCO2 (PtcCO2), which is linearly related to arterial PCO2, was continuously recorded in healthy, adult, normal volunteers for 8-h periods. Recording this variable with the apparatus employed permits measurement of changes in the level of ventilation while subjects are freely ambulant and unencumbered by invasive and flow-resistive respiratory apparatus. The time series obtained exhibited marked periodicities. The frequencies and amplitudes varied between subjects. Peak-to-peak variation was 10-20% of mean values. There was no apparent association between fluctuations in PCO2 and activity other than formal exercise. Visual inspection of the time series and preliminary statistical analysis of digitally converted data suggested that the time-dependent changes of PtcCO2 were normally distributed. However, more rigorous statistical examination revealed that in no case was PtcCO2 actually normally distributed.

Adult↗
PubMed1988

Hyperventilation in panic attacks. Ambulant monitoring of transcutaneous carbon dioxide.

Transcutaneous carbon dioxide monitoring has been used to investigate directly the frequency and role of hyperventilation during naturally occurring panic attacks in freely ambulant volunteers and patients. Illustrative preliminary data from healthy subjects and from four patients with panic attacks are presented. These confirm that some patients do hyperventilate during their attacks but indicate that some do not. The unreliability of traditional methods for identifying hyperventilators is demonstrated. These data indicate the potential of ambulant monitoring in research into hyperventilation and panic.

Adult↗
PubMed1987

Anxiety management for persistent generalised anxiety.

A preliminary controlled investigation of the effectiveness of Anxiety Management as a treatment for generalised anxiety disorder (GAD) is described. Patients with a primary diagnosis of GAD, in which the current episode had lasted for at least 6 months but not more than 2 years, were included. Anxiety Management, a self-help treatment including procedures for managing somatic and cognitive symptoms, and for dealing with avoidance and low self-confidence, was given either immediately or after a 12-week waiting period. The average length of treatment was 8.7 sessions. Highly significant changes in anxiety, depression, and problem ratings were shown after treatment. These changes were replicated when the waiting list group had also received treatment, and gains were maintained by both groups for 6 months. Similar degrees of improvement and maintenance of change were shown in subgroups with and without minor depressive disorder or recurrent panic attacks.

Adult↗
PubMedDate not supplied

An ambulatory system for long-term continuous monitoring of transcutaneous PCO2.

Apparatus suitable for continuous, ambulatory transcutaneous PCO2 monitoring is described. This consists of a Stow-Severinghaus transcutaneous sensor with a miniaturized amplifier and recorder. Its performance characteristics and vulnerability to artefact have been assessed. The procedure for prolonged ambulatory recording is outlined. The response time (for 67% of change) was 13 s in dry gas and 5 min on skin (the reasons for this difference are discussed). With 28 subjects, the between subject correlation (r) of transcutaneous and arterial PCO2 measurements was 0.97. After equilibration, recorded values drifted only occasionally. When it did occur, the average was 0.03 kPa X h-1 in dry gas and 0.1 kPa X h-1 on skin. There was no evidence of artefact due to changes in temperature or blood flow. Movement artefact were eliminated using an adequate attachment procedure. A number of healthy volunteers were monitored for up to 12 h while freely ambulant. In all subjects, small fluctuations in transcutaneous PCO2 were observed, of less than 0.5 kPa. The apparatus is of value in the assessment of conditions and situations in which acute change in ventilation has been implicated and for investigation of normal respiratory physiology with freely ambulant subjects.

Ambulatory Care↗