Simultaneous monitoring of somatosensory evoked potentials and regional cerebral oxygen saturation combined with serial measurement of plasma levels of cerebral specific proteins for the early diagnosis of postoperative brain damage in cardiovascular surgery

S100 and S100β: biomarkers of cerebral damage in cardiac surgery with or without the use of cardiopulmonary bypass

OBJECTIVE

The present study is to describe the clinical impact of S100 and S100β for the evaluation of cerebral damage in cardiac surgery with or without the use of cardiopulmonary bypass (CPB).

METHODS

Quantitative results of S100 and S100β reported in the literature of the year range 1990-2014 were collected, screened and analyzed.

RESULTS

Cerebrospinal fluid and serum S100 levels showed a same trend reaching a peak at the end of CPB. The cerebrospinal fluid/serum S100 ratio decreased during CPB, reached a nadir at 6 h after CPB and then increased and kept high untill 24 h after CPB. Serum S100 at the end of CPB was much higher in infant than in adults, and in on-pump than in off-pump coronary artery bypass patients. ∆S100 increased with age and CPB time but lack of statistical significances. Patients receiving an aorta replacement had a much higher ∆S100 than those receiving a congenital heart defect repair. Serum S100β reached a peak at the end of CPB, whereas cerebrospinal fluid S100 continued to increase and reached a peak at 6 h after CPB. The cerebrospinal fluid/serum S100β ratio decreased during CPB, increased at the end of CPB, peaked 1 h after CPB, and then decreased abruptly. The increase of serum S100β at the end of CPB was associated with type of operation, younger age, lower core temperature and cerebral damages. ∆S100β displayed a decreasing trend with age, type of operation, shortening of CPB duration, increasing core temperature, lessening severity of cerebral damage and the application of intervenes. Linear correlation analysis revealed that serum S100β concentration at the end of CPB correlated closely with CPB duration.

CONCLUSION

S100 and S100β in cerebrospinal fluid can be more accurate than in the serum for the evaluations of cerebral damage in cardiac surgery. However, cerebrospinal fluid biopsies are limited. But serum S100β and ∆S100β seem to be more sensitive than serum S100 and ∆S100. The cerebral damage in cardiac surgery might be associated with younger age, lower core temperature and longer CPB duration during the operation. Effective intervenes with modified CPB circuit filters or oxygenators and supplemented anesthetic agents or priming components may alleviate the cerebral damage.

Neurocognitive monitoring and care during pediatric cardiopulmonary bypass-current and future directions

Neurologic injury in patients with congenital heart disease remains an important source of morbidity and mortality. Advances in surgical repair and perioperative management have resulted in longer life expectancies for these patients. Current practice and research must focus on identifying treatable risk factors for neurocognitive dysfunction, advancing methods for perioperative neuromonitoring, and refining treatment and care of the congenital heart patient with potential neurologic injury. Techniques for neuromonitoring and future directions will be discussed.

Recent Advances in Application of Cerebral Oximetry in Adult Cardiovascular Surgery

Cerebral oximetry is a noninvasive technology that continuously monitors cerebral tissue oxygen saturation, which is a sensitive index of global cerebral hypoperfusion. On the basis of near-infrared spectroscopy technology, information is provided on the availability of oxygen in brain tissue at risk during numerous pathological conditions. Complementary to the arterial oxygen saturation measured by pulse oximetry, cerebral tissue oxygen saturation reflects regional cerebral metabolism and the balance of local cerebral oxygen supply/demand. Recently, patient management with the guidance of cerebral oximetry has resulted in improved patient outcomes. This review will briefly describe the physics behind cerebral oximetry and will provide an overview of the literature focusing primarily on articles published within the past 5 years.

Effects of temporary bilateral ligation of the internal carotid arteries on the low- and high-frequency somatic evoked potentials in the swine

OBJECTIVE

We studied effects of a temporary bilateral ligation of the internal carotid arteries on the subcortical and cortical structures of the somatosensory system by examining the thalamic input and postsynaptic cortical responses contained in the somatic evoked potentials (SEPs) recorded from the primary somatosensory cortex (SI) of the juvenile piglets in vivo. We predicted that the ligation should differentially affect these structures due to differences in blood supply.

METHODS

The SEPs between 1 and 3000 Hz were measured in the SI cortex with a multichannel electrode array before, during and after a 20 min bilateral ligation of the internal carotid arteries in the swine under a barbiturate anesthesia.

RESULTS

The ligation differentially affected the thalamic input and the cortical responses contained in the high-frequency signals (HFSs) between 400 and 2000 Hz. The amplitude of the thalamic input did not change, but the amplitudes of the cortical HFS postsynaptic to the thalamic inputs decreased immediately after start of ligation, recovering over the next 30-90 min. The latency showed a small, but significant increase for several minutes after the start of ligation for both the thalamic input and cortical responses. The ligation increased the latency and reduced the amplitude of the peak of the first cortical response in the wideband SEP corresponding to human N20.

CONCLUSIONS

The HFS is useful for distinguishing selective effects of the temporary ligation on the subcortical and cortical structures of the somatosensory system. Since the porcine N20 starts after the presynaptic HFS, it was not useful in differentiating thalamic and cortical effects.

SIGNIFICANCE

The HFS may open a new window in studying the cortical physiology in humans.