Anesthetic Management Guided by the Medstrom Instrument

This prospective randomized controlled trial (RCT) aims to evaluate the feasibility and safety of the integrated Medstrom monitoring system for real-time, comprehensive assessment of pain, sedation level, and neuromuscular blockade (NMB) during laparoscopic radical colectomy. It addresses significant limitations of conventional fragmented monitoring systems, such as data conflicts between independent devices (e.g., BIS for sedation, TOF for NMB, HRV for pain), delayed clinical interpretation, and suboptimal resource utilization.

The Medstrom technology utilizes palmar/plantar PAM sensors to objectively quantify pain via skin conductance peaks (SCP). SCPs are generated by emotional sweating triggered via spinal nociceptive reflexes, offering key advantages: objective pain quantification (SCP amplitude correlates with stimulus intensity), rapid response (within 1-2 seconds to noxious stimuli), resilience against hemodynamic instability, temperature variations, or medications, and the unique capability to simultaneously output validated sedation and neuromuscular indices. This single-device integration aims to replace the need for separate BIS, TOF, and HRV monitors.

The study design involves 45 patients (adjusted for 10% dropout from n=40) aged 18-65 years with ASA physical status I-III and confirmed colon cancer, undergoing elective laparoscopic radical colectomy. Key exclusions include BMI ≥30, significant organ dysfunction, neurological/neuromuscular disorders, and pregnancy. Participants are randomized into two groups:

• Medstrom-Guided Group (Intervention): Continuous monitoring using palmar/plantar sensors with real-time display of integrated pain, sedation, and NMB indices guiding anesthesia management.
• Conventional Monitoring Group (Control): Standard care using separate BIS (target 40-60) + TOF + standard hemodynamic monitoring.

A standardized anesthesia protocol is employed for both groups: Induction with Propofol (1.5-2.5 mg/kg) + Sufentanil (0.2-0.4 μg/kg) + Rocuronium (0.6-1.0 mg/kg), and Maintenance with Propofol (4-12 mg/kg/h) + Remifentanil (0.1-0.2 μg/kg/min) + bolus Rocuronium/Sufentanil as needed. Data collection occurs at 8 critical intraoperative timepoints, including intubation, skin incision, pneumoperitoneum, surgical end, and pre/post supplemental sufentanil administration.

The primary endpoints focus on establishing the feasibility and correlation of the Medstrom indices against current gold standards:

• Correlation of Medstrom-Pain vs. HRV (Pearson/Spearman).

Feasibility is defined by statistically significant correlations (p<0.05, adjusted for multiple comparisons using Bonferroni/Dunn-Šidák).

Secondary outcomes include hemodynamic stability (HR/MAP fluctuations), total anesthetic consumption, device-related adverse events (e.g., skin irritation, signal errors), and analysis of interactions between the integrated indices (using SEM/pathway analysis).

The statistical approach is based on a sample size of 40 (calculated for multivariate repeated measures: α=0.05, β=0.1/power=90%, effect size f²=0.15, variable correlation ρ=0.4), increased to N=45 to account for a 10% dropout rate. Analyses include correlation (95% CIs), consistency (Bland-Altman/ICC for agreement), multivariable comparisons (Hotelling's T² for correlated outcomes), and time effects (Linear mixed models with random intercepts).

This study holds innovative significance as the first RCT to validate a single-device, triple-parameter integrated monitoring system (pain, sedation, NMB) specifically in major abdominal surgery. It addresses critical clinical gaps: providing objective pain quantification (replacing subjective hemodynamic interpretation), minimizing device interference issues (e.g., BIS distortion by neuromuscular agents), and enhancing resource efficiency. The potential clinical impact includes reducing the risk of intraoperative awareness/pain recall and establishing a framework for more cost-effective and streamlined anesthesia management.

Inclusion criteria

• 1. Timeframe & Location: Patients treated at the First Medical Center of the Chinese PLA General Hospital between June 2025 and December 2026.

• Age: 18 to 65 years old. 3. Diagnosis: Pathologically confirmed colon cancer requiring laparoscopic radical resection.

• Physical Status: American Society of Anesthesiologists (ASA) Physical Status Class I-III.

• Informed Consent: Patients who voluntarily participate in the study and provide written informed consent.

Exclusion criteria

• 1. Body Mass Index (BMI): BMI ≥ 30 kg/m². 2. Organ Dysfunction: Severe concomitant cardiac, pulmonary, hepatic, or renal dysfunction.

• Neurological Conditions:

• History of autonomic nervous system disorders.
• Current use of medications affecting autonomic nervous system function.
• History of neuromuscular dysfunction. 4. Pregnancy/Lactation: Pregnant or lactating women. 5. Recent Surgery: History of secondary surgery within the preceding month. 6. Psychiatric/Cognitive Conditions:
• History of psychiatric disorders or cognitive impairment.
• History of psychotropic or narcotic drug abuse.
• Significant communication barriers.

Withdrawal Criteria:

1.Requirement for conversion to open surgery or other significant deviation from the planned laparoscopic approach due to intraoperative findings.