Regular low frequency cardiac output oscillations observed in critically ill surgical patients

Abstract

A serendipitous finding during development of an automated “electronic flow chart” system to gather data on ICU patients [1] was the observation of low frequency oscillations in blood pressure that were not explained by systematic variability in the environment. [2] This finding has since been confirmed by others. [3,4] In the present report, hemodynamic data for critically ill surgical patients was continuously collected and visualized on a computer workstation to search for patterns not noted by standard monitoring. With this system, we observed low‐frequency periodic oscillations in the cardiac output of ten patients, with regular periodicities of 4 to 280 minutes (average = 34 minutes). The mortality rate in these patients was 40%, while the mortality was only 10.8% in 83 similarly monitored intensive care unit (ICU) patients who did not develop regular oscillations in cardiac output. Interestingly, these oscillatory patterns appear to be associated with inadequate resuscitation of increased metabolic rates. The mathematical definition of “chaos” refers to irregular behavior that appears to be random but is actually deterministic. [5] A surprising finding concerning transitions between states of apparent randomness and order in nonlinear systems is that many systems become more organized after being disturbed. Chaotic behavior in biological systems may represent a normal physiologic state, while the loss of chaotic behavior may herald a pathophysiologic state. [6] The mechanism of the regular low frequency oscillations in cardiac output remains to be determined, but the high mortality rate suggests that it is a pathophysiologic marker, perhaps due to inadequate oxygen delivery in under‐resuscitated shock. © 1997 John Wiley & Sons, Inc.

Chaotic global analysis of heart rate variability following power spectral adjustments during exposure to traffic noise in healthy adult women

“…Chaotic global techniques are more responsive to erraticism in dynamical systems than those based on linear, time-domain, geometric methods, frequency domain or the nonlinear measurements [2]. Chaotic behaviour in biological systems typically indicates normal physiological status; while a reduction of chaotic tendencies could be a pathophysiological marker [13]. Such computations are beneficial when assessing surgical patients [13], particularly if sedated [14,15] or incapable of indicating discomfort as with sleep apnea [16] or those with "air hunger" [17,18].…”

“…Chaotic behaviour in biological systems typically indicates normal physiological status; while a reduction of chaotic tendencies could be a pathophysiological marker [13]. Such computations are beneficial when assessing surgical patients [13], particularly if sedated [14,15] or incapable of indicating discomfort as with sleep apnea [16] or those with "air hunger" [17,18]. We expected the subjects exposed to traffic noise to perform in a nonlinear manner equivalent to persons with cardiac arrest [19], epileptic seizures [20,21], chronic obstructive pulmonary disease (COPD) [22] or attention deficit hyperactivity disorder (ADHD) [8].…”

Oscillations in Cardiovascular Function During Acute Hypoxia in the Newborn Piglet Are Associated With Less Neurological Damage and Occur More Frequently in Females

“…Our own data have shown that serum cortisol concentrations are also related to neurologic damage and cardiovascular function, an effect which may be mediated via the activity of the sympathetic nervous system (SNS) (2). Several studies have reported that the cardiovascular system can exhibit an oscillating response during periods of stress, such as hypoxia and cerebral ischemia (3)(4)(5)(6). Oscillations in cardiovascular function occur at different frequencies.…”

“…In comparison, type-3 waves are slower with a cycle period of 10 to 160 s. They have been observed in the presence of hypoxia, hemorrhage, cold, endotoxic shock, and increased intracranial pressure (4). Type-3 waves in blood pressure have been reported to occur in neonatal rats during acute hypoxia (5).…”

21st ESICM Annual Congress

“…Cyclic blood pressure (BP) and cardiac output variation in varying frequencies and depth have been observed in critically ill patients ( 1 – 4 ). The slower cyclic variations are sometimes named Traube-Hering-Mayer waves.…”