Changes in Ventilation Inhomogeneity and Respiratory Function Following Elective Caesarean Section Under Regional Anaesthesia (VIRCA)

Changes in Ventilation Inhomogeneity and Respiratory Function Following Elective Caesarean Section Under Regional Anaesthesia: a Prospective Observational Study

Pregnancy is associated with physiological changes affecting the cardiorespiratory system as a consequence of an increase in both cardiac output and intra-abdominal pressure. The aim of this prospective observational study is to examine the perioperative changes in ventilation inhomogeneity and respiratory function measured by the non-invasive nitrogen multiple breath washout and forced oscillation techniques.

Study Overview

• Status: Withdrawn
• Conditions: Pregnancy
• Intervention / Treatment: Other: Physiologic measures of lung function

Detailed Description

Pregnancy is associated with physiological changes affecting the cardiorespiratory system as a consequence of an increase in both cardiac output and intra-abdominal pressure. These alterations lead to a ventilation/perfusion mismatch which is potentiated by a decrease in functional residual capacity (FRC). These effects explain why pregnant women are more prone to the occurrence of hypoxemia, particularly in the third trimester of their pregnancy. The importance of the ventilation inhomogeneity can be estimated from the lung clearance index (LCI) measured by the non-invasive nitrogen multiple breath washout (N2 MBW) technique. Moreover the loss in lung volume is associated with reduction in respiratory system compliance, which can also be assessed non-invasively by the forced oscillation technique (FOT).

To our knowledge, there is no existing data on LCI or FRC using the aforementioned techniques in pregnant women. Furthermore, existing data on respiratory function in pregnant women is largely restricted to spirometric and body plethysmographic measurements taken primarily in the 1970s-1980s. As such, the important roles of lung ventilation inhomogeneity as well as the potential changes following birth after caesarean section have yet to be completely characterised.

• Study Type: Observational

Contacts and Locations

Study Locations

• Switzerland
  • Geneva, Switzerland, 1206
    • University Hospitals of Geneva

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

• Sampling Method: Non-Probability Sample

Study Population

Pregnant women scheduled for elective caesarean section in gestational weeks 37-40

Description

Inclusion Criteria:

• Written informed consent
• Pregnant woman in the third trimester (37-40 weeks gestational age)
• Scheduled for elective caesarean section under regional (spinal or combined spinal-epidural) anaesthesia

Exclusion Criteria:

• Pregnant women outside 37-40 weeks gestational age
• Non-singleton pregnancy
• Previous history of ≥2 caesarean sections
• History or clinical signs of cardiopulmonary disease in the last 12 months (chronic hypertension, gestational hypertension, preeclampsia, asthma, acute or chronic bronchitis, others)
• Positive current smoking status
• Pre-pregnant body mass index (BMI) >30 kg/m2 (based on booking records)
• Respiratory infection <2 weeks prior to surgery
• Inability to perform the respiratory function tests

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Perioperative changes in ventilation inhomogeneity (LCI) following delivery by caesarean section	Nitrogen multiple breath washout technique	1-3 days prior to caesarean section until 5 days postoperative

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Alterations in FRC throughout the postpartum period	Nitrogen multiple breath washout technique	1-3 days prior to caesarean section until 5 days postoperative
Changes in respiratory mechanics: respiratory system compliance (Crs)	Forced oscillation technique	1-3 days prior to caesarean section until 5 days postoperatively
Changes in respiratory mechanics: airway resistance (Raw)	Forced oscillation technique	1-3 days prior to caesarean section until 5 days postoperatively
Perioperative respiratory complications	Apnoea/bradypnoea, oxygen desaturation <90%/hypoxemia, hypoventilation/atelectasis, pulmonary embolism, incoercible cough	During caesarean section until 5 days postoperatively
Perioperative respiratory interventions	Intubation, oxygen therapy, bronchodilator, adrenaline, continuous positive airways pressure (CPAP), respiratory physiotherapy	During caesarean section until 5 days postoperatively

Collaborators and Investigators

• Sponsor: Walid HABRE
• Investigators: Study Director: Walid Habre, MD, PhD, University of Geneva

Study record dates

Study Major Dates

• Study Start: May 1, 2016
• Primary Completion (Anticipated): October 1, 2016
• Study Completion (Anticipated): October 1, 2016

Study Registration Dates

• First Submitted: March 1, 2016
• First Submitted That Met QC Criteria: March 15, 2016
• First Posted (Estimate): March 21, 2016

Study Record Updates

• Last Update Posted (Estimate): November 1, 2016
• Last Update Submitted That Met QC Criteria: October 30, 2016
• Last Verified: October 1, 2016

More Information

Terms related to this study

• Keywords: Lung volume; Functional Residual Capacity; Lung Clearance Index; Respiratory function
• Other Study ID Numbers: VIRCA-2016

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO