None listed
Conditions
Brief summary
Currently, cardiac assessment of critical care patients involves the analysis of changes in aortic pressure, cardiac output, central venous pressure, heart rate, ECG and gas exchange measurements relative to a normal or “average” patient. However, complex interactions in these measurements can hide the underlying disease state so that clinicians receive no clear picture of overall circulatory status or function. This research proposes to use a computer model of the CVS to aggregate the clinical data into a more readily understood physiological context for clinicians, by exposing hidden dynamics, and thus allowing a stronger foundation for treatment selection. This study tests the ability of the CVS model to monitor and characterize cardiac disturbances in a critical care setting. During the observation period, the participants will receive interventions which are determined by clinical judgement and which follow standardized protocols. These interventions will involve administering fluids, medicines that increase blood pressure and stimulate the heart, and changing ventilator settings, which are known to impact on the circulation. Each participant’s CVS response will be recorded and all interventions will be consistent with normal clinical practice.
Interventions
A series of short therapeutic interventions will be performed on study patients following a pre-defined protocol:
1. A thermo-dilution will be performed at the start of each study to assess cardiac output and correctly reflect the patient’s volume status.
2. Optimizing ventilator settings by adjusting the PEEP level will help quantify fluid responsiveness. PEEP will be varied +/-5 cmH2O from the clinically-determined setting. The changes in CVS responses will be recorded.
3. Patients are ofte
A series of short therapeutic interventions will be performed on study patients following a pre-defined protocol: 1. A thermo-dilution will be performed at the start of each study to assess cardiac output and correctly reflect the patient’s volume status. 2. Optimizing ventilator settings by adjusting the PEEP level will help quantify fluid responsiveness. PEEP will be varied +/-5 cmH2O from the clinically-determined setting. The changes in CVS responses will be recorded. 3. Patients are often given infusions of adrenaline and/or noradrenaline (heart stimulants) which are titrated to a clinical response. No formal protocols exist to guide clinicians. This treatment is largely carried our using intuition and experience. The clinically-determined inotrope dose will be changed +/- 20% with increments of 1 mcg/min every 5 minutes. At each change in dose, the CVS responses will be recorded. The reason for this exercise is to assess the patients sensitivity to the drugs they are receiving. The maximal change in noradrenaline or adrenaline will be limited to 5 mcg/min. For example a patient receiving an infusion of noradrenaline at 10 mcg/min will have their infusion changed to 8,9,10,11,12 mcg/min for up to 5 minutes at each setting. After this the patients infusion will be returned to starting rate (10 mcg/min) or as clinically indicated.
Sponsors
University of Canterbury
Study design
Allocation
Non-randomised trial
Primary purpose
Diagnosis
Eligibility
Sex/Gender
Male
Age
16 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Post-cardiac surgery or diagnosed CVS dysfunction as leading contributor to ICU admission; Arterial and central venous catheterization; and full or intermittent mechanical ventilation (intubated).
Exclusion criteria
Moribund or not expected to survive 48 hours; patient not intubated or does not have required catheters for measurements.
Outcome results
None listed