Not applicable- observational study: Observation of hemodynamic parameters before and after clinically indicated norepinephrine dose reduction. No investigator-initiated intervention was performed.
Study summary
This study prospectively observes changes in critical closing pressure (Pcc) and derived hemodynamic parameters in mechanically ventilated distributive shock patients when clinically indicated norepinephrine dose reduction is performed by the attending physician. Pcc is measured before and 30 minutes after dose reduction using a stepwise inspiratory hold maneuver via PiCCO monitoring.
Eligibility
Sex
ALL
Min age
18 Years
Max age
—
Healthy volunteers
No
Inclusion Criteria:
1. Adult distributive shock patients aged ≥18 years;
2. Receiving norepinephrine infusion with MAP in the 75-85 mmHg range;
3. PiCCO catheter in situ;
4. Under mechanical ventilation;
5. Clinically indicated norepinephrine dose reduction per attending physician judgment.
Exclusion Criteria:
1. Significant cardiac arrhythmia affecting CO measurement reliability;
2. Contraindication to airway plateau pressure maneuver;
3. Active titration of other vasoactive agents within 30 minutes prior to measurement;
4. Hemodynamic instability making it impossible to reduce norepinephrine dose.
Primary outcome measure(s)
Change in critical closing pressure (Pcc, Unit: mmHg) before and after norepinephrine dose reduction — Baseline and 30 minutes after norepinephrine dose reduction Pcc is derived from linear regression of simultaneously measured cardiac output against mean arterial pressure during stepwise inspiratory hold maneuvers via PiCCO monitoring. The x-intercept of the regression line (at zero flow) represents Pcc. Measurement is performed at baseline and 30 minutes after norepinephrine dose reduction.
Change in tissue perfusion pressure (TPP, unit: mmHg) before and after norepinephrine dose reduction — Baseline and 30 minutes after norepinephrine dose reduction TPP is calculated as the difference between mean arterial pressure (MAP) and critical closing pressure (Pcc): TPP = MAP minus Pcc, unit: mmHg
Trial sites (1)
Facility
City
Region
Status
Peking Union Medical College Hospital
Beijing
Beijing Municipality
Recruiting
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This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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