Cranial Neurosurgery
Conditions
Keywords
HRV, heart rate variability, EEG, electroencephalography, EEG patterns, EEG signatures, pEEG, processed EEG, Neurosurgery, Monitoring, PACU, Post Anesthesia Care Unit, Autonomous Nervous System, Cortical Function, Outcome after Neurosurgery, Post Operative Period, Post Operative Monitoring, Post Operative Outcome, Anesthesia, Emergence, Awakening, Recovery
Brief summary
Patients undergoing cranial neurosurgery face a high-risk postoperative period, particularly during emergence from anesthesia and early recovery in the post-anesthesia care unit (PACU). Standard monitoring provides limited insight into brain and autonomic recovery processes. Heart rate variability (HRV) and processed electroencephalography (pEEG) may offer complementary markers of autonomic and cortical function, with potential to improve early detection of complications and guide individualized care.
Detailed description
Patients undergoing cranial neurosurgery face a particularly vulnerable postoperative course. The immediate hours after surgery represent a high-risk window, as the transition from anesthesia to recovery is marked by abrupt physiological shifts and the potential for neurological or systemic instability. As patients transition from deep anesthesia to consciousness, dynamic fluctuations in autonomic tone and cortical activity reflect the brain's ability to recover from surgical and anesthetic stress. Smooth emergence and extubation are therefore essential: coughing, hypertension, or surges in intracranial pressure (ICP) can endanger hemostasis and compromise brain protection. Most serious complications-such as intracranial bleeding, cerebral edema, ischemia, hydrocephalus, or herniation-tend to arise within the first hours after surgery. The Post Anesthesia Care Unit (PACU) constitutes a important window of observation. At this critical phase many strategies have been developed to protect the brain from complication triggering events. For example, remifentanil infusion-whether manual or target-controlled at effect-site concentrations, like adopted at our institution, titrated to suppress airway reflexes and blunt cardiovascular responses-have been shown to promote safe and controlled awakening while preserving prompt neurological evaluation(1-6), facilitating the identification of surgical from anesthetic causes of delayed recovery. Any unrecognized or delayed deterioration early after surgery may herald potentially warning signs, highlighting the need for accurate, physiology-based monitoring to support timely detection and intervention. Standard monitoring-focused largely on vital signs-offers limited insight into the underlying brain and autonomic processes that govern recovery. Heat rate variability (HRV) and processed electroencephalography (pEEG) features, may provide novel means to characterize patient vulnerability in the PACU, improving risk stratification and guiding individualized perioperative care.
Interventions
None listed
Sponsors
Fondazione I.R.C.C.S. Istituto Neurologico Carlo Besta
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Adult patients (≥18 years) scheduled for elective cranial neurosurgery. * Planned extubation in the PACU after surgery. * Ability to obtain high-quality ECG and EEG recordings intra- and postoperatively (≥60 min expected PACU monitoring). * Written informed consent signed preoperatively.
Exclusion criteria
* Pre-existing severe cardiac arrhythmias (e.g., atrial fibrillation, frequent ectopy) or pacemaker dependence. * Known severe autonomic neuropathy (e.g., advanced diabetes, Parkinson's disease with autonomic failure). * Preoperative conditions associated with abnormal EEG (status epilepticus, uncontrolled seizures, sedative/hypnotic overdose). * Intraoperative or immediate postoperative events necessitating continued mechanical ventilation or ICU admission (e.g., massive bleeding, intraoperative arrest). * Inability to provide informed consent (e.g., cognitive impairment, language barrier without interpreter). * Refusal of informed consent
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Temporal trajectories of HRV and pEEG after Neurosurgery in the PACU | 1 year | Quantitative assessment of autonomic and cortical recovery during the entire period of PACU staying until 120 minutes after extubation or PACU discharge 1. Heart Rate Variability (HRV) parameters derived from continuous ECG recording, including: Time-domain indices: RMSSD (ms) SDNN (ms) Frequency-domain indices: LF power (ms²) HF power (ms²) LF/HF ratio (dimensionless) HRV will be calculated from high-resolution ECG signals using validated software following international standards (Task Force of the European Society of Cardiology and North American Society of Pacing and Electrophysiology). 2. Processed EEG (pEEG) parameters obtained from a commercial depth-of-anesthesia monitor, including: Processed EEG index value (dimensionless scale, 0-100) Spectral edge frequency (Hz) Relative alpha and delta power (% of total EEG power) Measurements will be extracted in predefined 5-minute epochs during of PACU monitoring |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Correlation Between HRV/pEEG Parameters in PACU and Incidence of Early Postoperative Complications Within 48 Hours | 48 hours after surgery | Association between HRV and pEEG parameters (RMSSD, SDNN, LF/HF ratio, pEEG index, spectral edge frequency) measured during the first 60 minutes in PACU and the occurrence of predefined postoperative complications within 48 hours. Postoperative complications will include: * Intracranial hemorrhage * Cerebral edema * Hydrocephalus * Ischemic events * Delirium * Reintubation * Unplanned ICU admission Complications will be recorded as a binary variable (presence/absence). The strength of association will be quantified using: * Odds Ratios (OR) from multivariable logistic regression models * Area Under the Receiver Operating Characteristic Curve (AUC) Unit of Measure: * Incidence (% of patients with complication) * Odds ratio (dimensionless) * AUC (0-1 scale) |
| Correlation Between HRV/pEEG Parameters and Perioperative Drug Exposure | Intraoperative period | Correlation between HRV/pEEG parameters measured in PACU and intraoperative anesthetic and opioid exposure including: * Total propofol dose (mg) * Total remifentanil dose (µg) * Effect-site concentration at end of surgery (µg/mL or ng/mL) The relationship will be quantified using: * Pearson or Spearman correlation coefficients (r) * Multivariable linear regression coefficients (β) Unit of Measure: * Drug dose (mg, µg) * Effect-site concentration (µg/mL or ng/mL) * Correlation coefficient (r, -1 to +1) |
| Correlation Between HRV/pEEG Parameters and Perioperative Clinical Variables | Intraoperative period | Correlation between PACU HRV/pEEG parameters and: * Duration of surgery (minutes) * Intraoperative hypotension duration (minutes below MAP threshold) * Estimated blood loss (mL) * ASA physical status classification Association will be assessed using: * Pearson/Spearman correlation * Multivariable regression models Unit of Measure: * Minutes * mL * ASA class (categorical scale) * Correlation coefficient (r) |
| Feasibility and Data Quality of HRV and pEEG Monitoring in PACU | First 60 minutes of PACU stay | Assessment of feasibility and signal quality of ECG and pEEG recordings during PACU monitoring, including: * Percentage of analyzable ECG epochs (%) * Percentage of analyzable EEG epochs (%) * Artifact burden (% of recording time excluded) Unit of Measure: Percentage (%) |
Countries
Italy
Contacts
CONTACTAndrea Gentile, MD
CONTACTMarco Gemma, M.D.
Outcome results
None listed