ABSTRACT
BACKGROUND: Chronic alcoholism represents a risk factor for cardiac arrhythmias. One underlying mechanism is a sympathetically dominated autonomic imbalance. This is especially apparent during acute withdrawal from alcohol. Since linear analysis of heart rate variability may not be entirely adequate to detect such autonomic dysfunction in acute alcohol withdrawal, we applied novel non-linear parameters and measures for cardio-respiratory coupling. METHODS: 20 patients suffering from acute alcohol withdrawal syndrome and 20 controls were included. For patients, heart rate and respiration were recorded on admission, after medication and at discharge. From these data, complexity measures (symbolic dynamics, approximate entropy) of heart rate modulation and respiration as well as parameters for cardio-respiratory coupling (coherence, cross-approximate entropy) which relate to vagal function were calculated. RESULTS: Heart rate modulation was significantly less complex in patients acutely admitted for alcohol withdrawal. Furthermore, coupling between beat-to-beat (RR) intervals and respiration time series was significantly diminished. Of the parameters assessed, cross-approximate entropy showed a trend for correlation with symptom severity. CONCLUSION: These data indicate diminished vagal function in acute alcohol withdrawal. Applying the methods described thus allows a sensitive detection of vagal neuropathy in this disease.
Subject(s)
Cardiovascular Physiological Phenomena/drug effects , Central Nervous System Depressants/adverse effects , Ethanol/adverse effects , Respiratory Mechanics/drug effects , Substance Withdrawal Syndrome/physiopathology , Adult , Alcoholism/psychology , Algorithms , Chlormethiazole/therapeutic use , Entropy , Heart Rate/drug effects , Humans , Hypnotics and Sedatives/therapeutic use , Male , Multivariate Analysis , Psychiatric Status Rating Scales , Substance Withdrawal Syndrome/drug therapy , Vagus Nerve/physiopathologyABSTRACT
BACKGROUND: Many symptoms of alcohol withdrawal (AW) such as tachycardia or elevated blood pressure might be explained by increased peripheral and central adrenergic activity. In contrast to many neurochemical studies of sympathetic activation during AW, only very few studies investigated autonomic balance using neurophysiological methods. METHODS: We investigated heart rate variability (HRV) and sympathetic skin response (SSR) in male patients suffering from mild AW syndrome (n = 20, no treatment required) and in patients with moderate to severe AW syndrome (n = 20, clomethiazole treatment) in the acute stage. Sympathovagal influence was quantified using measures of time and frequency domain of HRV as well as modern nonlinear parameters (compression entropy). Furthermore, we obtained latencies and amplitudes of SSR to quantify isolated sympathetic influence. Measures were obtained during the climax of withdrawal symptomatology before treatment, 1 day after climax, and shortly before discharge from hospital. Alcohol withdrawal scores were obtained and correlated to autonomic measures. RESULTS: Ambulatory blood pressure and AW scores revealed characteristic withdrawal symptoms in both patient groups. Apart from the nonlinear parameter compression entropy, Hc, measures of HRV revealed no sign of autonomic dysfunction in contrast to the significantly increased heart rates at the time of admission. Latencies and amplitudes of SSR did not indicate any increase of sympathetic activity. A negative correlation was found between Hc and mental withdrawal symptoms. CONCLUSIONS: We show here that classical measures for autonomic nervous system activity such as HRV and SSR are not suitable for describing the autonomic changes seen in acute AW, although a major role for the sympathetic nervous system has been proposed. This might be due to multiple dysregulation of metabolites in AWS or to subtle alcohol-induced damage to neuronal structures, issues that should be addressed in future studies.
Subject(s)
Central Nervous System Depressants/adverse effects , Ethanol/adverse effects , Galvanic Skin Response/physiology , Heart Rate/physiology , Substance Withdrawal Syndrome/physiopathology , Adult , Alcohol Withdrawal Delirium/physiopathology , Autonomic Nervous System/physiology , Chlormethiazole/therapeutic use , GABA Modulators/therapeutic use , Humans , Male , Middle Aged , Nonlinear Dynamics , Substance Withdrawal Syndrome/drug therapyABSTRACT
Acute alcohol withdrawal is often associated with increased sympathetic activity, and a decreased baroreflex sensitivity (BRS) can be assumed. Parameters of heart rate variability (HRV), blood pressure variability (BPV), BRS as well as cardiac index (CI), left ventricular work index (LVWI) and total peripheral resistance (TPR) were investigated in 20 patients undergoing acute alcohol withdrawal and matched controls. Measures were obtained during the peak of withdrawal symptomatology prior to treatment as well as 2 and 24h under continuous clomethiazole treatment. Alcohol withdrawal scores were obtained and correlated with autonomic measures. In addition, parameters were assessed in 15 subjects who abstained from alcohol after long-term intake. We found a severe down-regulation of BRS during acute alcohol withdrawal and to a milder extent in abstained alcoholics. Furthermore, HRV and BPV did not unequivocally reveal signs of elevated sympathetic activity. Non-linear parameters of HRV and parameters of BRS correlated with the severity of AWS. The distinct decrease of BRS in AWS and in long-term abstained subjects described here is of importance since similar alterations have been identified as independent prognostic factors for cardiac mortality in other diseases.
