Cerebrospinal Acid-base in Pregnant and Non-pregnant Fertile Women

Overview

The third trimester of pregnancy is typically characterized by the development of a marked respiratory alkalosis. The possible role of pregnancy-induced variations of cerebrospinal fluid (CSF) acid-base characteristics on the development of hypocapnic alkalosis is still unknown. Aim of this study is to characterize, according to Stewart's approach, the acid-base equilibrium of CSF and arterial plasma of pregnant women and compare the results with data obtained from fertile, non-pregnant women.

Full Title of Study: “Effects of Pregnancy on the Physico-chemical Characteristics of Cerebrospinal Acid-base Equilibrium”

Study Type

  • Study Type: Observational
  • Study Design
    • Time Perspective: Prospective
  • Study Primary Completion Date: April 2019

Detailed Description

The reduction in plasma PCO2 correlates with gestational age and was shown to be associated to plasma progesterone concentrations. We hypothesize that pregnancy-related haemodilution, inducing a reduction in CSF Strong Ion Difference (SID), might have a role in the development of pregnancy-related hypocapnic alkalosis. Samples of CSF and arterial plasma of pregnant women with gestational age > 35 weeks undergoing spinal anesthesia for elective caesarean section will be analyzed for blood gases, pH, electrolytes, osmolality, albumin and haemoglobin concentration. In addition plasma copeptin levels will be analyzed. The same measurements will be performed in fertile, non-pregnant women undergoing spinal anesthesia for elective surgery.

Interventions

  • Diagnostic Test: Acid – Base characterization
    • Samples of cerebrospinal fluid and arterial blood will be collected anaerobically to measure acid-base variables, electrolytes, albumin, progesterone and copeptin levels

Arms, Groups and Cohorts

  • Pregnant Women
    • Pregnant women with gestational age > 35 weeks undergoing spinal anesthesia for elective cesarean section.
  • Control Group
    • Fertile, non-pregnant women undergoing spinal anesthesia for elective surgery.

Clinical Trial Outcome Measures

Primary Measures

  • Strong Ion Difference
    • Time Frame: 1 day
    • Strong Ion Difference (expressed in milliequivalents per Liter [mEq/L]) of cerebrospinal fluid and arterial plasma

Secondary Measures

  • Partial pressure of carbon dioxide (PCO2)
    • Time Frame: 1 day
    • PCO2 (expressed in millimeters of Mercury [mmHg]) of cerebrospinal fluid and arterial plasma
  • Sum of albumin (expressed in mmol/L) and Phosphates (expressed in mmol/L)
    • Time Frame: 1 day
    • The total amount of weak non carbonic acids, i.e. the sum of albumin and phosphates (both expressed in mmol/L) of cerebrospinal fluid and arterial plasma
  • Difference between cerebrospinal fluid and arterial plasma Strong Ion Difference (Delta SID)
    • Time Frame: 1 day
    • The difference between plasma and cerebrospinal fluid SID (expressed in mEq/L) will be calculated as marker of electrolyte inbalance between these two extracellular fluid compartments. Delta SID = SIDcsf – SIDplasma
  • Difference between cerebrospinal fluid and arterial plasma partial pressure of CO2 (Delta PCO2)
    • Time Frame: 1 day
    • The difference between cerebrospinal fluid and arterial plasma PCO2 (expressed in mmHg) will be calculated as a marker of acid-base equilibrium between these two extracellular fluid compartments. Delta PCO2 = SIDplasma – SIDcsf
  • Progesterone levels
    • Time Frame: 1 day
    • Plasma and CSF Progesterone levels (expressed in ng/mL) will be measured
  • Copeptin levels
    • Time Frame: 1 day
    • Plasma copeptin levels (expressed in pmol/L) will be measured as a marker of antidiuretic hormone activity

Participating in This Clinical Trial

Inclusion Criteria

  • Pregnancy with gestational age > 35 weeks – Scheduled elective cesarean section under spinal anesthesia Exclusion Criteria:

  • known respiratory or neurologic disease – multiple pregnancies

Gender Eligibility: Female

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico
  • Collaborator
    • University of Milan
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Thomas Langer, MD, Principal Investigator, University of Milan
    • Antonio Pesenti, MD, Study Director, University of Milan
    • Edoardo Calderini, MD, Study Chair, Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico di Milano
    • Giorgio Giudici, MD, Study Chair, University of Milan
    • Mariateresa Ambrosini, MD, Study Chair, Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico di Milano
  • Overall Contact(s)
    • Thomas Langer, MD, +390250320463, thomas.langer@unimi.it

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