The effects of heart rate variability biofeedback in patients with preterm labour.

Preterm birth is a highly prevalent phenomenon that was shown to be associated with mental stress during pregnancy (Rich-Edwards and Grizzard in Am J Obstet Gynecol 192(5 Suppl):S30-S35, 2005). We aimed to assess the effects of heart rate variability (HRV)-biofeedback in patients with preterm labour. Therefore, we conducted a controlled randomized parallel group study in 48 female patients aged 19-38 years (median = 29) with preterm labour at gestational week 24th-32nd (median = 29th). In this study, one group (n = 24) attended six sessions of HRV-biofeedback over 2 weeks whereas patients of the other group (n = 24) were assigned to control sessions. In the HRV-biofeedback treated group, perception of chronic stress was decreased 4 weeks after completion of training compared to baseline (p < 0.05) but there was no change in the control group. In the HRV-biofeedback group, preterm birth was seen in 3 patients (13 %) whereas in the control group, preterm delivery occurred in 8 patients (33 %, p = n.s.). There was no difference in birth weight between groups and HRV remained unchanged. In conclusion, our study demonstrates that HRV-biofeedback can reduce chronic stress in patients with preterm labour when administered as an adjunct to routine care. However, it remains unclear whether stress reduction through HRV-biofeedback has a beneficial effect on preterm birth.

[Influence of rescue service personnel's shift work on psycho-physical parameters]. / Einfluss der Schichtarbeit im Rettungsdienst auf psychophysische Parameter.

BACKGROUND: The aim of the investigation was to receive information about the interaction between psycho-physical parameters as a function of the strain by shift work for rescue service personnel. MATERIAL AND METHODS: We examined 26 persons, who are active in the rescue service. The investigations always took place in the morning between 7.00 and 8.00 o'clock, either after 3 days off (n = 26), after 3 night shifts (n = 14) or in the morning of the third day shift (n = 14). The investigations included measurements of blood pressure, heart rate variability, and salivary cortisol. Additionally, standardized questionnaires (WHO-5, EBF 72/3) were used. RESULTS: A significant rise of the quotient LF/HF--as indicator for a sympathetic dominance--could be proven by means of a simple three minute arithmetic task at every investigation (after 3 days off from 0.81 to 2.30; p < 0.001). By means of the EBF a clear impairment could be demonstrated after 3 night shifts. Fatigue and somatic complaints were the main outcomes. In our study a more impaired well-being was associated with a more pronounced decrease of salivary cortisol (r = 0.538; p < 0.05) as well as lower blood pressure values (r = 0.547; p < 0.05), and a lower LF/HF quotient (r = 0.836; p < 0.01), indicating lower sympathetic and/or increased vagale activation, after three night shifts. CONCLUSIONS: After three night shifts a lower sympathetic activation seems to negatively affect the well-being. Due to the provable specific strain night- and shift-workers should be a priority target group for prevention and workplace health promotion.

The effects of lorazepam on skin conductance responses to aversive stimuli in healthy subjects.

BACKGROUND: Autonomic responses to aversive stimuli are widely used to model anxiolytic drug effects in healthy humans. Benzodiazepine anxiolytics dose dependently attenuate autonomic responses to aversive stimuli by their anxiolytic as well as sedative action. The present study aimed to examine the effects of non-sedative doses of lorazepam on skin cutaneous responses to aversive stimuli and subjective mood. METHODS: A randomized, double blind, cross over study of 12 healthy male volunteers aged 24 years (23-32; median; range) was carried out. Subjects received single oral doses of 0.5 and 1.0 mg lorazepam as well as placebo on three different occasions with at least 5 days in-between. Skin conductance responses (SCRs) to unpleasant pictures and noises, pupillary unrest index as well as subjective levels of anxiety were measured repeatedly before and after drug administration. RESULTS: SCRs were found significantly lower 2 hours following ingestion of 0.5 mg lorazepam as well as 1, 2 and 3 hours after 1.0 mg lorazepam were given as compared to baseline conditions. By contrast, administration of placebo did not influence SCRs to a significant extent. Both doses of lorazepam did not change pupillary unrest index nor subjective mood. CONCLUSIONS: Lorazepam may attenuate SCRs to aversive stimuli without affecting vigilance nor subjective mood. Attenuation of autonomic responses to aversive stimuli may not be specific for an anxiolytic effect.

Quantification of inspiratory-induced vasoconstrictive episodes: a comparison of laser Doppler fluxmetry and photoplethysmography.

Laser Doppler fluxmetry (LDF) or photoplethysmography (PPG) are frequently used as non-invasive tools to assess skin blood flow. They are both thought to be suitable and interchangeable methods for the detection of sympathetically activated vasoconstrictive episodes that can be provoked by a voluntary deep inspiration (DI), the so-called inspiratory gasp response (IGR). However, a rigorous comparison of the two methods has not been reported in the literature. The aim of this study was to compare the detection of IGR with LDF and PPG. We investigated 14 healthy volunteers (five female, nine male, 25.4 +/- 2.7 years). A PPG probe was applied to the tip of the thumb of the dominant hand, a LDF sensor to the tip of the adjacent index finger. After adaptation and baseline measurements the subjects were asked to perform a DI with time intervals of 90, 60, 30 and 15 s. We found that both methods are useful to detect individual IGR. Overall correlation of IGR amplitude detected with LDF and PPG was significant (r=0.433). Surprisingly, there was a continuous increase of the correlation coefficient from the first (r=0.105) or second (r=-0.184) IGR to the fifth (r=0.727) IGR. This implies that experimental data obtained with PPG and LDF are not equivalent and that one has to be cautious regarding the comparison and interpretation of results obtained with these two different methods.

Effects of sertraline on autonomic and cognitive functions in healthy volunteers.

RATIONALE: Though sertraline, a selective serotonin reuptake inhibitor (SSRI), causes autonomic and cognitive adverse events such as dry mouth and somnolence, there is a paucity of appropriately designed studies on the cognitive and autonomic effects of the drug in the literature. OBJECTIVE: To compare the effects of sertraline on cognitive and autonomic functions with those of placebo in healthy humans. METHOD: A randomized, double blind, cross over study of 12 healthy male volunteers aged 24 (21- 32; median; range) years. Subjects orally received 50 mg sertraline and placebo once daily for periods of 14 days each with at least 14 days in between. Heart rate variability (HRV), skin conductance level (SCL) and skin conductance response (SCR) following sudden deep respiration were employed as parameters for autonomic function. Quantitative EEG (qEEG) and psychometric tests served as parameters for cognitive function. Measurements were performed repeatedly before the start of drug administration and on the last treatment day. RESULTS: Sertraline caused a significant reduction of heart rate and SCL ( P<0.05), whereas HRV and SCR were not changed. Cognitive functions such as flicker fusion frequency, memory, choice reaction time and psychomotor performance were not influenced by sertraline but slow and fast beta power density in the qEEG was increased. CONCLUSION: Cognitive and psychomotor performance are not altered in healthy humans receiving multiple dosing with sertraline. The observed decreases in heart rate and SCL may be due to a sympatho-inhibitory effect of sertraline.

Agreement of two different methods for measurement of heart rate variability.

BACKGROUND: The widespread use of affordable devices with sufficient precision for measurement of heart rate variability (HRV) might lead to early detection of abnormalities in a large number of high-risk patients and athletes. The purpose of this study was to determine the limits of agreement of two devices for measuring HRV parameters differing in price and assumed precision. SUBJECTS AND METHODS: 36 healthy subjects (22 men and 14 women) with a mean age of 27.4 (SD 11.1) years were included. The two devices used for comparison were PowerLab with Chart software as the reference golden standard, and Polar Transmitter/Advantage with Precision Performance software, respectively. Measurements included the following heart rate variability parameters: heart rate, range of R-R-interval duration, SDNN, rMSSD, total Power, VLF power, LF power, and HF power. Measurements were taken during metronomic respiration over a total period of 3 minutes. Statistical analysis was performed according to Bland and Altman and by means of scatterplots and Spearman correlation coefficients. RESULTS: Good agreement was found for heart rate (95 % CI of limits of agreement: -0.7-0.6 bpm; r = 0.999), range of duration of R-R-intervals (95 % CI: -18.9-17.0 ms; r = 0.997), rMSSD (95 % CI: -1.5-2.5 ms; r = 0.999), and SDNN (95 % CI: -3.0-3.1 ms; r = 0.997). Correlation of measurements was high for the variables total Power, VLF power, LF power, and HF power. Analysis of method agreement for frequency domain variables was statistically not feasible. CONCLUSION: The level of agreement for the analyzed time domain variables between the reference golden standard and the inexpensive device is sufficient to permit initial screening by family doctors, and self-administration by high-risk patients and athletes.