The goal of this observational study is to study a new method to compute ventricular-arterial coupling (VAC) in adult intensive care patients after cardiac surgery. VAC is a metric that describes the interaction between the heart and the arterial system. The new method of measuring VAC uses carotid ultrasound measurements. The main questions this study aims to answer are:

• Can VAC measured using carotid ultrasound predict the hemodynamic response to drugs?
• What is the concordance of VAC measurements obtained via carotid ultrasound with VAC measurements obtained via the standard, single-beat method? Measurements will be performed in the operating room and at the ICU.

The goal of this prospective observational study is to study ventricular-arterial coupling (VAC) measured using carotid ultrasound in adult intensive care patients after cardiac surgery. The objectives of this study are:

• To determine if VAC measured using carotid ultrasound can predict the hemodynamic response to drugs.
• To assess and quantify the concordance of VAC measurements obtained using carotid ultrasound with VAC measurements obtained using the single-beat method.

Measurements will be performed in the operating room and at the ICU.

Inclusion Criteria:

• Adult patients (≥18 years)
• Admitted to the ICU after cardiac surgery

Exclusion Criteria:

• No informed consent for study participation
• Within the first 3 hours of ICU admission noradrenaline infusion is not increased or started, and/or a fluid bolus is not given; both on indication of the attending physician
• Patient with chronic obstructive pulmonary disease (COPD) gold stage 3 or 4
• Pregnancy
• Moderate to severe aortic valve disease
• Atrial fibrillation
• Carotid artery stenosis >50%
• History of cerebrovascular accident or transient ischemic attack
• History of cerebral trauma
• Morbid obesity (BMI >40 kg/m2)
• Emergency surgery

Adult ICU patients after cardiac surgery.