Hemodynamic Monitoring in Obstetrics
Condition: Hypotension
MeSH terms: Hypotension
Study type: Observational

Summary: 
      Spinal anesthesia has long been considered the first choice technique in caesarean section,
      but although it is a reliable and safe procedure, it is in some cases associated with
      undesirable effects. Maternal hypotension after sub-arachnoid anesthesia is a reduction in
      systolic blood pressure below 100 mmHg or a decrease of 20% compared to baseline values.
      According to some authors, maternal hypotension occurs up to 80% in women undergoing
      caesarean section after spinal anesthesia. In order to reduce the incidence of maternal
      hypotension, some measures can be taken:

        -  a reduction of aorto-caval compression by manual displacement of the uterus on the left;

        -  hemodynamic monitoring;

        -  administration of fluids;

        -  optimization of the dosage of the local anesthetic;

        -  use of vasopressors.

      The main objective of the study is to investigate, through the use of a continuous
      non-invasive hemodynamic monitoring system (Clearsight® - Edwards Lifesciences), the
      incidence of hypotension in pregnant women at risk undergoing spinal anesthesia due to
      elective cesarean section.
    

Detailed description: 
      In this prospective observational not-for profit study, 128 patients will be enrolled to
      measure the incidence of hypotension during spinal anesthesia for elective cesarean section.
      On the occasion of the preoperative visit, all patients to be subjected to elective cesarean
      section will be subjected to the Postural Change Test (PCT), a predictive test for maternal
      hypotension during spinal anesthesia that evaluate changes in heart rate of pregnant women
      following postural changes. Specifically, after monitoring the heart rate in the supine
      position, the patient is asked to change decubitus (from supine to left lateral and then back
      to supine). The test is positive if the patient's heart rate changes more than 10% from
      baseline.

      Once arrived in the obstetric emergency department, parturients with positive Postural Change
      Test will be subjected to cannulation of a peripheral vein through a 18-20 Gauge needle
      cannula and the Clearsight hemodynamic monitoring system will be placed on a finger. The
      investigators will then proceed to the detection of the following parameters:

        -  Mean Blood Pressure (MAP);

        -  Heart Rate (HR);

        -  Stroke volume (SV);

        -  Stroke volume Index (SVI);

        -  Cardiac Index (CI). These data will be collected and reported in the data sheet of the
           study, at different time points (T0 - T9). Basal values will be collected at T0 and T1:
           at T0 when the patient is in the supine position and at T1 when the patient is in a
           lateral position. The investigators will then proceed to the administration of a
           crystalloid bolus (10 ml/kg) and to the execution of spinal anesthesia (T2). The spinal
           block needle will be inserted, compatibly to the patient's anatomical conditions, at the
           L3-L4 / L4-L5 spaces. 0.5% hyperbaric Bupivacaine (5 mg/ml) will be administered at a
           dose depending on the patient's weight and height.

      Once the spinal block has been performed, the patient will be immediately placed in a supine
      position. The investigators will then continue monitoring the parameters listed above using
      Clearsight® (SV, SVI, MAP, CI) at 2-minute intervals in the phases following spinal
      anesthesia:

        -  T3: 2 minutes after spinal anesthesia,

        -  T4: 4 minutes after spinal anesthesia,

        -  T5: 6 minutes after spinal anesthesia,

        -  T6: 8 minutes after spinal anesthesia. The other measurements will be made at skin
           incision (T7), uterine incision (T8) and extraction (T9).

      Any hemodynamic changes (MAP <60 mmHg or CI <2.5), under volemic optimization conditions,
      will be treated by administration of vasoconstrictors (Etilefrine, intravenous bolus of 1-3
      mg).

      At the afterbirth, the investigators will proceed to the infusion of liquids and uterotonic
      according regimens in use at the unit of Anesthesia and Intensive Care of the Universitary
      Hospital "G. Rodolico" of Catania.

      Given the descriptive nature of the study, a formal calculation of the sample size was not
      made. As secondary end-points, the Stroke Volume variation following spinal anesthesia, the
      amount of fluids administered, the vasoconstrictor doses used, diuresis, the Apgar index and
      the fetal pH will be measured. The number of hypotension episodes not detected by the
      traditional blood pressure monitoring system but detected by the Clearsight system will also
      be recorded. For the qualitative variables, the absolute frequencies and the percentage
      frequencies will be calculated. For the quantitative variables, if with normal distribution,
      mean and standard deviation will be calculated; if with not normal distribution, median and
      interquartile range will be calculated.

      The normality of the distribution will be evaluated through the Kolmogorov-Smirnoff test.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        148 pregnant women, at risk of developing hypotension, undergoing spinal anesthesia for
        elective Caesarean section at the Universitary Hospital "G. Rodolico" of Catania
      
Keywords: Intraoperative hypotension; Caesarean section; Spinal anesthesia