Effect of Vasopressin vs Norepinephrine on Pulmonary Oxygenation and Lung Mechanics in Patients With Hypertension Therapy During One-lung Ventilation : Preliminary Study

Effect of Vasopressin vs Norepinephrine on Pulmonary Oxygenation and Lung Mechanics in Patients With Hypertension Therapy During One-lung Ventilation : Preliminary Study

Effect of Vasopressin vs Norepinephrine on Pulmonary Oxygenation and Lung Mechanics in Patients With Hypertension Therapy During One-lung Ventilation : Preliminary Study

Hypotension during anesthesia often occurs because reduced systemic vascular resistance and blocked sympathetic nervous system by anesthetic drugs. In patients who are taking hypertension medication, blood pressure drops are exaggerated by inadequate compensation mechanism due to decrease of blood vessel elasticity and desensitization of baroreceptors. In one-lung ventilation (OLV) during thoracic surgery, persistent perfusion of non-ventilatory lungs can lead to increased intra-pulmonary shunt and hypoxemia. As a compensatory mechanism, the gravitational effect and hypoxic pulmonary vasoconstriction occur. Among these, hypoxic pulmonary vasoconstriction is associated with pulmonary vascular resistance. Norepinephrine and vasopressin, which are commonly used in patients with hypotension, affect systemic and pulmonary vascular resistance. However, no studies have been done on lung oxygenation and pulmonary mechanics of these vasoactive drugs in patients undergoing surgery on one lung. Therefore, the purpose of this study is to investigate the effects of vasoactive drugs, norepinephrine and vasopressin, in patients with hypertension.

Patients enrolled were divided into norepinephrine (group N) and vasopressin (group V) by random random numbers. The ratio of each group should be 1: 1.

Patients, care givers and outcomes assessors are blinded. The investigator should not be included in the blind because the drug must be rate controlled during investigations.

In group N, 16 mcg / cc of norepinephrine was infused through the central catheter. Drug titration should be 0.05 mcg / min / kg for norepinephrine and 2 units / hr for vasopressin, until target blood pressure is reached. Drug infusion rate should not exceed 0.3mcg / min / kg for norepinephrine and 10unit / hr for vasopressin for patient's safety.

In group V, 0.4 unit / cc of vasopressin was infused through the central catheter and the respective doses recorded. Drug titration should be 0.05 mcg / min / kg for norepinephrine and 2 units / hr for vasopressin, until target blood pressure is reached. Drug infusion rate should not exceed 0.3mcg / min / kg for norepinephrine and 10unit / hr for vasopressin for patient's safety.

Inclusion Criteria: Adult patients aged 40-80 years who are planning to have thoracoscopic single lobectomy with unilateral lung ventilation during surgery. Patients taking hypertension drug CCB(calcium channel blocker), ARB(angiotensin II receptor blocker), ACEi(ACE inhibitor, angiotensin converting enzyme inhibitor) at least 4 weeks. American Society of Anesthesiologists (ASA) classification 2~3 Exclusion Criteria: patients with heart failure (NYHA class III~IV) patients who are having moderate obstructive lung disease or restrictive lung disease Low DLCO (< 75%) patients with pulmonary hypertension (mean PAP>25mmHg) patients with liver disease (AST level ≥100 IU/mL or ALT ≥ level 50 IU/L) or kidney disease (Creatine level ≥ 1.5 mg/dL) body mass index (BMI) > 30 kg/m2 patients who cannot read explanation and consent form patients who are pregnant

Department of Anaesthesiology and Pain Medicine, Anaesthesia and Pain Research Institute, Yonsei University College of Medicine