Critical Illness, Distributive Shock, Hemodynamic Assessment
Conditions
Keywords
Critical closing pressure, Tissue perfusion pressure, Vascular waterfall, Norepinephrine dose, Distributive shock
Brief 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.
Detailed description
In distributive shock patients receiving norepinephrine with MAP maintained in the 75-85 mmHg range, attending physicians may reduce norepinephrine dose based on clinical judgment. This study observes hemodynamic changes associated with such reductions without any investigator-initiated intervention. Critical closing pressure (Pcc) and derived parameters including tissue perfusion pressure (TPP), mean systemic filling pressure analogue (Pmsf), and vascular waterfall (VW) are measured at baseline and 30 minutes after dose reduction, provided MAP variability is less than 5 mmHg. Pcc is derived from linear regression of simultaneously measured cardiac output (CO) and mean arterial pressure (MAP) during stepwise inspiratory hold maneuvers. Steady-state CO and MAP values are recorded during the final 3 seconds of 12-second inspiratory holds at plateau pressures of 5, 15, 25, and 35 cmH2O. The x-intercept of the CO-MAP regression line is taken as Pcc.
Interventions
OTHERNot applicable- observational study
Observation of hemodynamic parameters before and after clinically indicated norepinephrine dose reduction. No investigator-initiated intervention was performed.
Sponsors
Peking Union Medical College Hospital
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 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 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in mean systemic filling pressure analogue (Pmsf, unit: mmHg) before and after norepinephrine dose reduction | Baseline and 30 minutes after norepinephrine dose reduction | Pmsf is estimated as the x-intercept of the linear regression of cardiac output against central venous pressure (CVP), representing the venous pressure at zero flow. |
| Change in Vascular waterfall (VW, unit: mmHg) before and after norepinephrine dose reduction | Baseline and 30 minutes after norepinephrine dose reduction | Vascular waterfall (VW) is calculated as Pcc minus Pmsf. |
| Change in capillary refill time (CRT, unit: seconds） | Baseline and 30 minutes after norepinephrine dose reduction | Capillary refill time is assessed by applying pressure to the fingertip for 5 seconds and measuring the time for color to return after release. |
Countries
China
Contacts
CONTACTBin Du, Dr
Outcome results
None listed