Critical Illness

Acute Disease

Shock

University Medical Center Groningen

Simple Intensive Care Studies I (SICS-I)

Combining Conventional With Advanced Hemodynamic Parameters for Predicting the Outcome of Critically Ill Patients: a Pilot for a Registry

Primary outcome of the basic study, answering our diagnostic research question
We calculated cardiac index, which was derived from cardiac output. Cardiac output has been measured with the cardiac probe M3S of M4S with default cardiac imaging setting of the General Electric Vivid-S6 mobile ultrasound machine. Two views were obtained: the parasternal long axis (PLAX) and the apical five chamber view (AP5CH). The PLAX was used as the primary view to measure the left ventricular outflow tract (LVOT) diameter. The AP5CH view was used to measure the velocity time integral (VTI) using the pulse wave Doppler signal in the LVOT. Cardiac output was calculated on the ultrasound machine according to the formula: Cardiac output (L/min)=heart rate ∙VTI∙π∙(1/2∙LVOT)^2
Clinical examination findings have been collected during a one-time physical examination, which is further specified at the study description section.

Primary outcome of the basic study, answering our prognostic research question.
Clinical examination findings, as well are specified at the study description section.
Biochemical values are serum lactate, creatinine and hemoglobine (see study description).
Hemodynamic variables are obtained from advanced patient monitoring devices, such as invasive central venous or arterial blood pressures, echocardiographic measurements, etc.
Follow-up on all-cause mortality will be obtained from the municipal personal records database. Analysis of mortality will be performed using time-to-event data (patients were censored at 90-days of follow-up).

Secondary outcome of the basic study, answering our diagnostic research question.
For this outcome, we will determine the cut-offs as follows:
Use a cardiac index cut-off of 2.2 L/min/m2
Identify the optimal cut-off(s) for cardiac index. We will use dot plots to assess the distribution of cardiac index stratified by the presence or absence of each (combination of) clinical examination finding(s) that indicate hypoperfusion. We will conduct a logistic regression with the dichotomised clinical examination finding as dependent variable and cardiac index as independent variable, including the assumed covariate(s) of each finding, and compute receiver operating characteristic (ROC)-curves to identify the optimal cut-off(s).

Secondary outcome of the basic study, answering our diagnostic research question.
If the sample size permits, we will conduct subgroup analysis in different subpopulations. We will create the following subgroups in the basic study and test both our prognostic and diagnostic hypotheses on:
Subgroup 1: subdivide the population into three groups: no shock, shock associated with a low cardiac output, shock associated with a high cardiac output.
Subgroup 2: subdivide the population by underlying pathologies that could influence the haemodynamic measurements in a patient: Patients admitted due to cardiac arrest, myocardial infarction, after liver transplantation or liver failure, and severe sepsis. Patients admitted or known with heart failure, central nervous system pathologies, and severe chronic cardiovascular disease.

Secondary outcome of the basic study, answering our prognostic research question.
This will be a sensitivity analyses on different follow-up times of mortality.

Secondary outcome of the basic study, answering our prognostic research question.
Variables not visible to caregivers are some of our clinical examination findings and cardiac index measurements. Clinical examination findings that were not shared with caregivers, were: capillary refill times, mottling scores and peripheral temperature measurements.

Secondary outcome of the basic study, answering our prognostic research question.
If the sample size permits, we will conduct subgroup analysis in different subpopulations. We will create the following subgroups in the basic study and test both our prognostic and diagnostic hypotheses on:
Subgroup 1: subdivide the population into three groups: no shock, shock associated with a low cardiac output, shock associated with a high cardiac output.
Subgroup 2: subdivide the population by underlying pathologies that could influence the haemodynamic measurements in a patient: Patients admitted due to cardiac arrest, myocardial infarction, after liver transplantation or liver failure, and severe sepsis. Patients admitted or known with heart failure, central nervous system pathologies, and severe chronic cardiovascular disease.

Substudy 1 - primary outcome
StO2 was measured by NIRS with the Inspectra StO2 tissue oxygenation monitor, model 650 (Hutchinson Technology, Inc., Hutchinson, Minnesota, USA). We used a 15-mm probe to measure the StO2 at a depth of 14mm at two sites: the thenar eminence and the distal end of the vastus medialis muscle. The average StO2 value was calculated over 30 seconds after one minute of signal stabilisation.

Substudy 2 - primary outcome
Pulmonary ultrasound was conducted with the cardiac probe M3S of M4S with default cardiac imaging and maximal frequency (3.6 MHz) setting of the General Electric Vivid-S6 mobile ultrasound machine. We measured the presence or absence of B-lines at the six locations specified in the BLUE-protocol. The presence of a B-profile was defined by three or more B lines observed in at least three of the six BLUE points, or in two of the four lower BLUE points.
Pulmonary oedema was diagnosed by the radiologist who reviewed chest radiographs as part of daily care. The radiologist was blinded for the variables collected in our study.

Substudy 2 - secondary outcome
The presence of a B-profile was defined by three or more B lines observed in at least three of the six BLUE points, or in two of the four lower BLUE points.

Substudy 3 - primary outcome
Cardiac output was measured using the same ultrasound machine, probes, views and formulas as described in the primary outcome of the basic study.
During the PEEP-challenge, an additional 10 cm H2O of PEEP was temporarily applied when supervised by the treating ICU physician. The PEEP was elevated for a maximum duration of 5 minutes during which the changes in cardiac output, heart rate, blood pressures and central venous pressure were recorded.

Substudy 4 - primary outcome
TAPSE and RV s' have been measured with the cardiac probe M3S of M4S with default cardiac imaging setting of the General Electric Vivid-S6 mobile ultrasound machine. Both measurements were obtained in the AP4CH view. TAPSE was assessed in M-mode, after placing the cursor on the junction of the tricuspid valve and the RV free wall. RV s' was assessed in the tissue velocity imaging mode highlighting the area of interest. The pulsed Doppler sample volume was placed at the tricuspid level of the RV free (i.e. lateral) wall and the longitudinal velocity of excursion was measured.

Substudy 5 - primary outcome
Common carotid artery, subclavian artery, and common femoral artery flows have been measured with the linear probe 8L or 9L and default carotid setting of the General Electric Vivid-S6 mobile ultrasound machine.

Substudy 5 - secondary outcome
A proxy for abdominal flow was calculated by subtracting flow over both left and right carotid, subclavian and femoral arteries from the cardiac output.
AKI was established and classified following the kidney disease: improving global outcomes (KDIGO) criteria. Urine output and serum creatinine measurements from the first 72 hours of inclusion were analysed to establish and classify AKI for each patient.

Substudy 6 - primary outcome
Cardiac output has been estimated with the FloTrac (Edwards Lifesciences, Irvine, California, USA) and a monitor to compute stroke volume and cardiac output (Vigileo, Edwards Lifesciences, Irvine, California, USA). The FloTrac analyses the arterial pressure waveform to compute stroke volume and cardiac output. The estimated cardiac output was compared to the cardiac output measured with the General Electric Vivid-S6 mobile ultrasound machine.

Substudy 7 - primary outcome
We repeated the measurements of the variables collected in the basic study, sub-study 2, and sub-study 4. We performed these measurements 24 hours (minimum 22 to maximum 26 hours) after the first measurement and calculated differences. The sign of the variable indicates whether a variable has either increased (positive number) or decreased (negative number).

Substudy 8 - primary outcome
Right ventricle diameters and tricuspid regurgitation velocity have been measured with the cardiac probe M3S of M4S with default cardiac imaging setting of the General Electric Vivid-S6 mobile ultrasound machine. The measurements were obtained in the AP4CH view with a right ventricle centred view.
AKI was established and classified following the kidney disease: improving global outcomes (KDIGO) criteria. Urine output and serum creatinine measurements from the first 72 hours of inclusion were analysed to establish and classify AKI for each patient.

Substudy 9 - primary outcome
Every passive leg raising manoeuvre was conducted for a maximum duration of 60 seconds during which the changes in cardiac output, heart rate, blood pressures, central venous pressure, and EtCO2 were recorded. Fluid responsiveness was diagnosed when cardiac output increased with 15% after the PLR-test.

Substudy 9 - primary outcome
During the fluid responsiveness study, two different PLR tests were applied when supervised by the treating ICU physician.

Substudy 9 - secondary outcome
Fluid responsiveness was diagnosed when cardiac output increased with 15% after the PLR-test. The PEEP-challenge was conducted in a similar manner as described in sub-study 3.

Substudy 10 - primary outcome
ARDS will be defined according to the Berlin ARDS criteria: 1) presence of acute hypoxemic respiratory failure defined by a PaO2/FiO2 ratio < 300 mm Hg and PEEP ≥ 5 cm H2O; 2) onset within one week of clinical insult or worsening respiratory symptoms; 3) bilateral consolidations on chest radiography or CT-thorax.

Substudy 10 - secondary outcome
Clinical examination findings, as well are specified at the study description section.
Biochemical values are serum lactate, creatinine and hemoglobine (see study description).
Hemodynamic variables are obtained from advanced patient monitoring devices, such as invasive central venous or arterial blood pressures, echocardiographic measurements, etc.

Substudy 11 - primary outcome
Myocardial strain and myocardial strain rates have been measured with the cardiac probe M3S of M4S with default cardiac imaging setting of the General Electric Vivid-S6 mobile ultrasound machine. The measurements were obtained in the AP4CH window with a left ventricle and right ventricle centred view for left and right myocardial strain, respectively.

heart murmurs/οίδημα

Simple Intensive Care Studies I (SICS-I)

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