Comparison of Two Different Norepinephrine Bolus Doses for Management of Spinal Anesthesia-Induced Maternal Hypotension

In this study the investigators will compare two doses of norepinephrine bolus (6 mcg and 8 mcg) in management of maternal hypotensive episode after spinal block during cesarean delivery.

Maternal hypotension after spinal anesthesia is a common and serious complication during cesarean delivery. Despite all preventive measures, the incidence of hypotension is still around 20%. In these cases, maternal hypotension treatment is usually required using vasopressor boluses. One of the vasopressors commonly used during cesarean delivery is norepinephrine, especially recently.

Although phenylephrine has long been the first choice for the prevention and treatment of maternal hypotension, its use may cause bradycardia and decreased maternal cardiac output.

Norepinephrine is an alpha adrenergic agonist with weak beta adrenergic agonistic activity; therefore, it does not cause significant cardiac depression like phenylephrine. Norepinephrine has been introduced for use during cesarean delivery with promising results. Several previous studies have investigated the efficacy of norepinephrine infusion in preventing maternal hypotension. A dose-response study investigated the best dose of Norepinephrine for the prevention of hypotension. In the dose-response study mentioned above, a dose of 6 mcg was reported as the best dose for prophylaxis against hypotension.

There are very limited studies investigating the best bolus dose of norepinephrine for the treatment of maternal hypotensive episode, and the optimal dose recommendation is uncertain. In this study, researchers will investigate the efficacy and adverse effects of two bolus doses of norepinephrine (6 mcg and 8 mcg) in the management of a maternal hypotensive episode after subarachnoid block during cesarean delivery.

Eligibility Criteria:
Inclusion Criteria:

* Woman,
* ASA I-II,
* 18-49 age range,
* Actual body weight \>50 kg,\<90 kg
* Actual height \>150cm, \<180cm
* Patients undergoing surgery under elective conditions and emergency cases for non-bleeding reasons
* Fasting period is appropriate,
* Term pregnancy (38-42 weeks),
* Patients without cardiovascular disease
* Spinal block that does not reach the high level (\<T4),
* Patients without diagnosis of stage 2 or higher hypertension hypertension (Stage 2 hypertension is defined as a systolic blood pressure of more than 160 mmHg and a diastolic blood pressure of more than 90 mmHg.),
* Patients without vasoactive drug use,
* Preop Systolic Blood Pressure \>90 mmHg,
* Bleeding less than 750 ml,
* Patients who signed the informed consent form to be included in the study

Exclusion Criteria:

* ASA III-IV,
* Pregnant women outside the age range of 18-49,
* Actual body weight \>90kg, \<50kg
* Actual height \>180cm, \<150cm
* Patients with inappropriate fasting time
* Preterm pregnancy (\<38 weeks) or postterm pregnancy (\>42 weeks)
* Bleeding amount more than 750 ml
* Emergency surgery with bleeding (previa, placental abruption, etc.)- Pregnant with cardiovascular system disease,
* High block level (\>T4)
* Having a diagnosis of stage 2 or higher hypertension hypertension (Stage 2 hypertension is defined as a systolic blood pressure of more than 160 mmHg and a diastolic blood pressure of more than 90 mmHg.),
* Use of vasoactive drugs,
* Preop Systolic Blood Pressure \<90 mmHg
* Patients who did not sign the informed consent form to be included in the study