In the reduction mammoplasty operations performed in the Plastic and Reconstructive surgery operating room in our clinic, the female patient group, who does not have co-morbidities and does not exceed middle age, is followed by infusion of crystalloid at a constant rate of 4 ml/kg. If the mean arterial pressure (MAP) is <65 mmHg, it is treated with fluid boluses, and in cases where no response is obtained, with noradrenaline boluses. However, in this process, frequent and severe hypotensive episodes are observed, especially after removal of more than a few kilograms of breast tissue. In these hypotensive episodes, factors other than the blood volume lost with the tissue may also play a role. For this reason, we aimed to evaluate the iNOS levels by assuming that the blood levels of "inducible nitric oxide synthetase" (iNOS), which is stored in large amounts in adipose tissues and has been shown to play a role in lipid metabolism, may increase with the manipulation of breast tissue, and accordingly increased nitric oxide may lead to hypotension.

The main purpose of intraoperative fluid therapy is to optimize intravascular volume, mean arterial pressure (MAP) and cardiac output, while ensuring tissue perfusion, while not causing dehydration and fluid overload in the patient. While hypovolemia may cause problems such as organ perfusion disorders and ischemia; Hypervolemia may lead to pulmonary edema, cardiac load, prolonged need for mechanical ventilation and susceptibility to related infections. Although fluid management in the perioperative period has been extensively studied in many studies, a standard practice has not been established. The amount considered restrictive in some studies may be liberal in others. In recent years, the use of dynamic parameters, which are formed as a result of cardiopulmonary interactions and whose high sensitivity and specificity have been proven by many studies, has been increasing day by day for the evaluation of intravascular volume. Pulse pressure variation(PPV) and stroke volume variation(SVV) are two of these dynamic parameters. The pulse contour cardiac output (FloTrac) system, which is a fairly newly developed method that calculates cardiac output and stroke volume directly from the arterial waveform, is used for measurement without the need for calibration.

In the reduction mammoplasty operations performed in the Plastic and Reconstructive surgery operating room in our clinic, the female patient group, who does not have co-morbidities and does not exceed middle age, is followed by infusion of crystalloid at a constant rate of 4 ml/kg. If the mean arterial pressure (MAP) is <65 mmHg, it is treated with fluid boluses, and in cases where no response is obtained, with noradrenaline boluses. However, in this process, frequent and severe hypotensive episodes are observed, especially after removal of more than a few kilograms of breast tissue. In these hypotensive episodes, factors other than the blood volume lost with the tissue may also play a role. For this reason, we aimed to evaluate the iNOS levels by assuming that the blood levels of "inducible nitric oxide synthetase" (iNOS), which is stored in large amounts in adipose tissues and has been shown to play a role in lipid metabolism, may increase with the manipulation of breast tissue, and accordingly increased nitric oxide may lead to hypotension.

Inclusion Criteria:

1. Volunteering to participate in the study
2. ASA classification 1 or 2
3. The patients who will undergo reduction mammoplasty operation

Exclusion Criteria:

1. Being under the age of 18 or over the age of 65
2. Presence of serious hypertension