Postspinal hypotension (PSH) is a common side effect with an incidence of 15.3 to 33% that can result in organ hypoperfusion and ischemic events. In pregnant patients, this incidence may increase to 70% and severe PSH increases the risk of maternal and fetal complications. Therefore, it is extremely important for anesthesiologists to recognize PSH early and treat it quickly during cesarean sections.

Integrated pulmonary index (IPI) is an algorithm that has been used recently. IPI takes into account four parameters: respiratory rate, end tidal CO2, heart rate and O2 saturation. Capnography device measuring IPI can continuously monitor and display the patient's respiratory status in a single digit range from 1-10. This index value can be observed continuously on the monitor as digital data or as a waveform. "10" indicates a normal respiratory condition, while "1" indicates that the patient requires immediate intervention. The relationship between values and the patient status is evaluated as follows; 10 = Normal, 8-9 = Normal range, 7 = Near normal range; Requires attention, 5-6 = Requires attention and may require intervention, 3-4 = Requires intervention, 1-2 = Requires immediate intervention.

IPI monitorization is mostly used during sedation (gastroscopy, cardioversion), intensive care units (for adjusting mechanical ventilator settings, monitoring the weaning process).

As a result, IPI monitoring has attracted attention because it allows non-invasive, dynamic and real-time measurement, reflects respiratory status with high specificity and sensitivity, and enables respiratory problems to be detected earlier.

End tidal CO2, which is one of the 4 parameters that IPI value takes into account, is a parameter that can be used to evaluate the effectiveness of ventilation, but is also related to cardiac output (CO) because the delivery of CO2 to the pulmonary system depends on it. Studies have shown that ETCO2 value correlatively decreases when CO decrease, in cases such as hypotension and hypovolemia.

We think that ETCO2 will decrease due to pulmonary hypoperfusion in post spinal hypotension and it may cause a change in IPI value. In our study, we will monitor patients who are scheduled for cesarean section under spinal anesthesia with a capnometry device and we will try to determine the significance of IPI monitorization in predicting hypotension.

Patients who underwent cesarean section under spinal anesthesia and who agreed to participate in the study will be included in the study.

Demographic data of the patients (age, gender, weight, concomitant diseases, etc.) will be recorded.

After spinal anesthesia, a non-invasive nasal cannula will be inserted into the patients, and ETCO2 and IPI values will be continuously measured and recorded from this cannula with a capnometry device.

As is routinely done, blood pressure will be measured at 2-minute intervals after spinal anesthesia is administered.

The non-invasive blood pressure value measured before spinal anesthesia will be taken as the baseline value, and a decrease of 20% or more in this value or a decrease in systolic blood pressure below 100 mmHg will be considered hypotension.

The correlation between the developing hypotension and the End tidal CO2 and IPI measurements will be examined.

Inclusion Criteria:

ASA I-II pregnants who will undergo cesarean section under spinal anesthesia

Exclusion Criteria:

• ASA III- IV Pregnants.
• Pregnants with chronic respiratory disorder.
• Pregnants who will undergo cesarean section under emergency conditions.

Pregnants above the age of 18 who will undergo cesarean section under spinal anesthesia