Evaluation of monitoring readings, taking into account each patient’s pathology as well as the impact of every medical intervention can guide us to make optimal clinical decisions in the periopeative setting. We present three cases in which clinical decisions concerning the management of acute perioperative pulmonary hypertension were based both on haemodynamic monitoring readings and on each patient’s specific pathology. First case: After anesthesia induction in a patient with severe aortic valve insufficiency, an increase in pulmonary artery pressure was recorded. Infusion of isoprenaline, which has a positive chronotropic effect, decreased diastolic time, diastolic blood flow into the left ventricle and also pulmonary artery pressure. Second case: A patient with severe aortic valve stenosis was found with increased pulmonary artery pressure. Intravenous administration of atenolol (1+1mg) reduced the heart rate and the pulmonary artery pressure. Third case: A 15 year old patient with aortic isthmus rupture underwent open surgical repair with graft interposition. After establishment of one lung ventilation and left thoracotomy, pulmonary artery pressure increased. Pulmonary hypertension was managed successfully by oxygen insufflation to the non-ventilated left lung. In our first patient, heart rate increase reduced diastolic time, which decreased the amount of retrograde blood flow into the left ventricle through the regurgitant aortic valve. In the second patient, the heart rate reduction decreased blood flow velocity through the stenotic aortic valve as well as the pressure gradient between left ventricular chamber and aorta. In both patients, enhanced left ventricular function resulted in a reduction in pulmonary artery pressure. Decrease of the alveolar partial pressure of oxygen (PAO2) is the most important parameter that stimulates hypoxic pulmonary vasoconstriction. Oxygen insufflation increased PAO2, resulting in a decrease in pulmonary artery pressure .Clinical decisions based on haemodynamic monitoring readings resulted in effective management of pulmonary hypertension and in a good patient outcome.