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Published on: September 15, 2023
Causality analysis reveals the link between cerebrovascular control and acute kidney dysfunction after coronary
Emanuele Vaini1, Vlasta Bari1, Angela Fantinato1
1Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy.
Insights
Impaired cerebrovascular control, indicated by reduced cerebral blood flow velocity (CBFV) regulation during coronary artery bypass graft (CABG) surgery, may predict acute kidney dysfunction (AKD) after the procedure.
Area of Science:
- Cardiovascular Physiology
- Nephrology
- Neuroscience
Background:
- Coronary artery bypass graft (CABG) surgery can lead to postoperative complications, including acute kidney dysfunction (AKD).
- Hypoperfusion is a potential cause of AKD following CABG.
- Impaired cerebrovascular control may indicate vascular damage and increase the risk of AKD.
Purpose of the Study:
- To characterize cerebrovascular control in CABG patients by analyzing the relationship between mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV).
- To identify markers of dynamic interactions between MCBFV and MAP that could predict postoperative AKD.
Main Methods:
- Beat-to-beat MAP and MCBFV data were collected from 23 patients before CABG under propofol anesthesia.
- Patients were categorized into AKD (n=9) and noAKD (n=14) groups post-surgery.
- Time-domain, spectral, and cross-spectral markers, along with transfer entropy (TE) between MAP and MCBFV, were computed.
Main Results:
- Traditional time, spectral, and cross-spectral markers showed limited ability to differentiate between AKD and noAKD groups.
- Transfer entropy from MAP to MCBFV was significantly elevated in the AKD group compared to the noAKD group.
- This elevated TE in AKD patients suggests a significant dependence of cerebral blood flow on arterial pressure.
Conclusions:
- Reduced cerebrovascular autoregulation, as indicated by transfer entropy, is a potential marker for identifying patients at risk of AKD after CABG.
- Impaired cerebrovascular control may predispose patients to hypoperfusion during CABG, contributing to the development of AKD.
Background:
Patients undergoing coronary artery bypass graft (CABG) surgery might experience postoperative complications and some of them, such as acute kidney dysfunction (AKD), are the likely consequence of hypoperfusion. We hypothesized that an impaired cerebrovascular control is a hallmark of a vascular damage that might favor AKD after CABG.
Objective:
Our aim is to characterize cerebrovascular control in CABG patients through the assessment of the relationship between mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV) and to check whether markers describing MCBFV-MAP dynamical interactions could identify subjects at risk to develop postoperative AKD.
Approach:
MAP and MCBFV beat-to-beat series were extracted from invasive arterial pressure and transcranial Doppler recordings acquired simultaneously in 23 patients just before CABG after the induction of propofol general anesthesia. Subjects were divided into AKD group (n = 9, age: 68 ± 9, 8 males) and noAKD group (n = 14, age: 65 ± 8, 12 males) according to whether they developed postoperative AKD or not after CABG. We computed MAP and MCBFV time-domain and spectral markers as well as MCBFV-MAP cross-spectral indexes in very-low-frequency (VLF, 0.02-0.07 Hz), low-frequency (LF, 0.07-0.15 Hz) and high-frequency (HF, 0.15-0.30 Hz) bands. We also calculated model-based transfer entropy (TE) to quantify the degree of MCBFV dependence on MAP and vice versa. The null hypothesis of MCBFV-MAP uncoupling was tested via a surrogate approach associating MAP and MCBFV in different patients.
Main Results:
Time, spectral and cross-spectral markers had a limited power in separating AKD from noAKD individuals. Conversely, TE from MAP to MCBFV was significantly above the level set by surrogates only in AKD groups and significantly larger than that computed in noAKD.
Significance:
The reduced cerebrovascular autoregulation in AKD patients suggest a vascular impairment likely making them more at risk of hypoperfusion during CABG and AKD after CABG.
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