Colloid Preload Versus Colloid Coload During Cesarean Deliveries

Colloid Preload Versus Colloid Coload in Preventing Spinal Anesthesia-Induced Hypotension During Cesarean Section Deliveries: A Prospective, Randomized, Double-Blind Comparative Study

The investigators aimed to compare the methods colloid preloading and colloid coloading in terms of the incidence of maternal hypotension and impacts on neonatal outcomes. The second aim while planning the present study is to identify the method of the lowest adverse event for mother and infant and the simplest approach for the clinician.

Spinal anesthesia (SA) is currently the most preferred method of anesthesia in elective cesarean deliveries. However, SA causes maternal hypotension by decreasing systemic vascular resistance over sympathetic blockade. Maternal hypotension can lead to serious adverse events both in mother and in fetus: fetal hypoxia and acidosis occur due to decreased uterine blood flow, whereas the mother may experience vertigo, nausea, vomiting, alteration in consciousness, cardiovascular collapse and arrest. Today, various strategies have been suggested for the prevention of maternal hypotension. Of these strategies, the most critical ones are fluid load before spinal anesthesia (preloading) or rapid fluid load just after spinal anesthesia (coloading) and the use of vasopressor agent. The fluids used for this purpose include crystalloids and colloids. Comparative studies performed with colloid preloading, colloid coloading and crystalloid coloading indicated that the incidence of hypotension decreased similarly with no significant difference determined between the methods of fluid loading. Researchers defended necessity of using vasopressor agent together with fluid loading methods. In daily routine; however, the investigators observe that the incidence of hypotension is lower in the patients that undergo colloid preloading as compared to the patients that undergo colloid coloading or crystalloid coloading. The investigators therefore aimed to compare the methods colloid preloading and colloid coloading in terms of the incidence of maternal hypotension and impacts on neonatal outcomes. In the present study, the investigators aimed to use 6% HES 130/0.4 (Voluven ®), which is the newer generation colloid solution. The other aim while planning the present study is to identify the method of the lowest adverse event for mother and infant and the simplest approach for the clinician.

Group Preloading (Group P): 500 mL hydroxyethyl starch (6% HES 130/0.4) (Voluven®; Fresenius Kabi, Bad Homburg, Germany) will be infused via a pressure infusion system at a maximum speed as possible before spinal anesthesia.

Group Coloading (Group C): After the patients have been monitored, spinal anesthesia will be performed. Recognizing the cerebrospinal fluid, 500 mL hydroxyethyl starch (%6 HES 130/0.4) (Voluven®; Fresenius Kabi, Bad Homburg, Germany) will be infused via a pressure infusion system at a maximum speed as possible.

Maternal hypotension will be defined as at least a single administration of ephedrine within the period from induction of SA to the delivery (umbilical cord clamping). After spinal anesthesia, SAP will be measured and recorded at every minute until birth and every three minutes thereafter.

Time between induction of spinal anesthesia until delivery (umbilical cord clamping). Participants will be followed for the duration of hospital stay, an expected average of two days.

Time between induction of spinal anesthesia until delivery (umbilical cord clamping). Participants will be followed for the duration of hospital stay, an expected average of two days.

Cumulative duration of hypotension will be recorded from induction of spinal anesthesia until delivery (umbilical cord clamping).

Time between induction of spinal anesthesia until delivery (umbilical cord clamping). Participants will be followed for the duration of hospital stay, an expected average of two days.

Time between induction of spinal anesthesia until delivery (umbilical cord clamping). Participants will be followed for the duration of hospital stay, an expected average of two days.

Arterial and venous blood gas analyses will be performed from the umbilical cord after the cord clamped.

Time just after delivery (umbilical cord clamping). Participants will be followed for the duration of hospital stay, an expected average of two days.

If SAB < 100 mmHg; patients will be treated by 5 mg IV bolus ephedrine, if SAB < 90 mmHg; patients will be treated by 10 mg IV bolus ephedrine.

Time between induction of spinal anesthesia until delivery (umbilical cord clamping). Participants will be followed for the duration of hospital stay, an expected average of two days.

Time between induction of spinal anesthesia until delivery (umbilical cord clamping). Participants will be followed for the duration of hospital stay, an expected average of two days.

Time before spinal anesthesia. Participants will be followed for the duration of hospital stay, an expected average of two days.

Before spinal anesthesia. Participants will be followed for the duration of hospital stay, an expected average of two days.

Time before spinal anesthesia. Participants will be followed for the duration of hospital stay, an expected average of two days.

Time period from induction of spinal anesthesia to skin incision (min), time period from induction of spinal anesthesia to delivery (min), time period from uterine incision to birth (sec), duration of anesthesia (min), and duration of surgery (min) will be recorded.

Time between induction of spinal anesthesia until end of the anesthesia. Participants will be followed for the duration of hospital stay, an expected average of two days.

Inclusion Criteria: Age 18 years or older Singleton pregnancy Gestational age ≥ 37 weeks Height ≥ 150 cm and ≤ 180 cm Weight > 50 kg and < 100 kg Exclusion Criteria: Gestational age > 37 weeks Multiple pregnancies Fetal distress Preeclampsia Cardiovascular disease and diabetes Hematological problems Local infection at intervention site Abnormal coagulation tests Anticoagulant use Starch allergy Height < 150 cm and > 180 cm Weight < 50 kg and > 100 kg