Duncan C. Galletly

Bio: Duncan C. Galletly is an academic researcher from University of Otago. The author has contributed to research in topics: Heart rate & Heart rate variability. The author has an hindex of 29, co-authored 70 publications receiving 1961 citations. Previous affiliations of Duncan C. Galletly include Wellington Management Company.

Effect of halothane, isoflurane and fentanyl on spectral components of heart rate variability

Abstract: We have examined the effect of isoflurane, halothane and fentanyl on heart rate variability (HRV) using power spectral analysis (PSA). Forty patients were allocated randomly to receive one of four anaesthetic techniques. Anaesthesia was induced with propofol 2 mg kg−1 and all patients breathed a mixture of 66% nitrous oxide in oxygen. Twenty of these spontaneously breathing patients received 1.5% isoflurane and 20 received 0.75% halothane. Ten patients in each of these groups received fentanyl 1 μg kg−1 before induction. PSA was performed on 5-min segments of beat-to-beat R-R interval data taken before and 5 min after induction. No significant difference was observed in time domain or spectral HRV measures between inhalation agents. Fentanyl was associated with significantly slower heart rates, although no difference was observed in the power spectrum of those receiving fentanyl. Analysis of pooled data from the 40 subjects showed that mean heart rate was unchanged and heart rate SD was decreased, as were total and individual powers in three frequency bands of the HRV spectrum (low 0.02–0.08 Hz, mid 0.08–0.15 Hz and high 0.15–0.45 Hz). A significant decrease in the ratio of high power to (low+mid) power indicated a shift towards sympatholysis with anaesthesia. However, a significantly greater depression of mid frequency components in comparison with low or high frequencies suggests that anaesthesia selectively depressed components of the HRV mechanism, independent of a general effect on autonomic tone.

Heart rate variability during propofol anaesthesia

Abstract: We have examined the effect of i.v. propofol anaesthesia on beat-to-beat heart rate variability. The power in all frequency bands (0.02–0.08, 0.08–0.15, 0.15–0.45 Hz) decreased, although the reduction in lower power was significantly less than that for mid (P = 0.001) and high (P = 0.04) power.

Knowledge of and attitudes towards resuscitation in New Zealand high-school students.

Abstract: Background: Introducing cardiopulmonary resuscitation (CPR) training in the high-school curriculum has been widely recommended as a long-term strategy to educate the wider community. Although CPR has been included in the New Zealand school curriculum, it is listed as an optional subject only. Aim: To assess the attitude towards and knowledge of CPR in 16–17-year-old high-school students in New Zealand. Methods: Questionnaires were administered to 494 students aged 16–17 years across six high schools in Wellington, New Zealand. Both knowledge and attitude were evaluated in the questionnaire. Results: Students showed poor theoretical knowledge, with a mean (SD) score of 5.61 (2.61) out of a maximum score of 18. Although there was no difference between male and female students, those who had received previous first-aid training (70%) showed greater knowledge (6.04 (2.56)) than their untrained counterparts (4.91 (2.24); p = 0.001). Those students with a positive attitude towards CPR and first-aid training (63%) acquired a higher knowledge score (6.12 (2.4)) than those with a negative attitude (17%; 4.65 (2.5); p = 0.001). Students with negative associations were also less likely to want to learn more about CPR and first aid (11%) when compared with those with positive associations (92%), and indicated less willingness to perform CPR on a stranger (negative v positive, 47% v 70%). Conclusions: These findings suggest that although most high-school students are willing and motivated to learn CPR, a smaller percentage of students had a negative attitude towards CPR that would act as a barrier to future learning or performance of resuscitation. Introducing CPR training to high schools is still recommended; however, this study shows the need to associate this training with positive references in an attempt to assist those for whom negative attitude may present as a barrier to learning and retaining CPR knowledge.

Cardioventilatory coupling in resting human subjects.

Abstract: In 48 conscious resting subjects we examined the temporal coupling of heart beat timing and the onset of inspiration (cardioventilatory coupling), and the relationship between coupling and spectral indices of autonomic function. Using the proportional Shannon entropy (SH(alpha)) of the RI(-1) interval (interval between inspiration and the preceding ECG R wave) as a measure of coupling we detected statistically significant coupling in 32 of the 48 subjects. This was confirmed by visual inspection of time series plots of RI intervals, in which coupling was evident as horizontal banding. Coupling resulted in a significant preference for whole number heart rate/respiratory frequency ratios. The strongest coupling was associated with low ventilatory frequency and high heart rate variability in the high (0.15-0.40 Hz) and low (0.04-0.15 Hz) frequency ranges, but was not related to blood pressure variability, or to a spectral measure of baroreflex sensitivity (alpha-index, low frequency range). There was no difference in coupling strength between males and females. We have previously described cardioventilatory coupling in spontaneously breathing anaesthetised subjects. The current study extends those observations by demonstrating that the qualitative features of coupling seen during anaesthesia are also observed in the conscious state. We conclude that the role of coupling in normal physiological respiratory control needs to be more widely explored.

Photoplethysmography and its application in clinical physiological measurement.

Abstract: Photoplethysmography (PPG) is a simple and low-cost optical technique that can be used to detect blood volume changes in the microvascular bed of tissue. It is often used non-invasively to make measurements at the skin surface. The PPG waveform comprises a pulsatile ('AC') physiological waveform attributed to cardiac synchronous changes in the blood volume with each heart beat, and is superimposed on a slowly varying ('DC') baseline with various lower frequency components attributed to respiration, sympathetic nervous system activity and thermoregulation. Although the origins of the components of the PPG signal are not fully understood, it is generally accepted that they can provide valuable information about the cardiovascular system. There has been a resurgence of interest in the technique in recent years, driven by the demand for low cost, simple and portable technology for the primary care and community based clinical settings, the wide availability of low cost and small semiconductor components, and the advancement of computer-based pulse wave analysis techniques. The PPG technology has been used in a wide range of commercially available medical devices for measuring oxygen saturation, blood pressure and cardiac output, assessing autonomic function and also detecting peripheral vascular disease. The introductory sections of the topical review describe the basic principle of operation and interaction of light with tissue, early and recent history of PPG, instrumentation, measurement protocol, and pulse wave analysis. The review then focuses on the applications of PPG in clinical physiological measurements, including clinical physiological monitoring, vascular assessment and autonomic function.

Heart Rate Variability and Cardiac Vagal Tone in Psychophysiological Research - Recommendations for Experiment Planning, Data Analysis, and Data Reporting.

Abstract: Psychophysiological research integrating heart rate variability (HRV) has increased during the last two decades, particularly given the fact that HRV is able to index cardiac vagal tone. Vagal tone, which represents the activity of the parasympathetic system, is acknowledged to be linked with many phenomena relevant for psychophysiological research, including self-regulation at the cognitive, emotional, social, and health levels. The ease of HRV collection and measurement coupled with the fact it is relatively affordable, non-invasive and pain free makes it widely accessible to many researchers. This ease of access should not obscure the difficulty of interpretation of HRV findings that can be easily misconstrued, however this can be controlled to some extent through correct methodological processes. Standards of measurement were developed two decades ago by a Task Force within HRV research, and recent reviews updated several aspects of the Task Force paper. However, many methodological aspects related to HRV in psychophysiological research have to be considered if one aims to be able to draw sound conclusions, which makes it difficult to interpret findings and to compare results across laboratories. Those methodological issues have mainly been discussed in separate outlets, making difficult to get a grasp on them, and thus this paper aims to address this issue. It will help to provide psychophysiological researchers with recommendations and practical advice concerning experimental designs, data analysis, and data reporting. This will ensure that researchers starting a project with HRV and cardiac vagal tone are well informed regarding methodological considerations in order for their findings to contribute to knowledge advancement in their field.

Part 8: Advanced Life Support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

Abstract: Part 8 : Advanced life support : 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations