Continous Cardiac Output - Non-Invasive Evaluation (CONNIE) (CONNIE)

The Performance of a Capnodynamic Method Compared to Transpulmonary Thermodilution in Open Abdominal Surgery

The capnodynamic method non-invasively calculates effective pulmonary blood flow (EPBF) continuously during surgery. In this study EPBF is compared to cardiac output (CO) measured with Transpulmonary Thermodilution (TPTD) att baseline and during hemodynamic changes in patients scheduled for open abdominal surgery at the Karolinska University Hospital, Solna, Sweden.

Study Overview

• Status: Completed
• Conditions: Cardiac Output, Low; Cardiac Output, High
• Intervention / Treatment: Device: Capnodynamic method; Device: Transpulmonary thermodilution

Detailed Description

The capnodynamic method continuously calculates effective pulmonary blood flow (EPBF) with the help of a capnodynamic equation:

ELV x (FACO2(n) - FACO2(n-1)) = deltat(n) x EPBF (CvCO2 - CvCO2(n)) - VTCO2

ELV Effective lung volume [L] EPBF Effective pulmonary blood flow [L/min] n current breath n-1 previous breath FACO2 mean alveolar carbon dioxide fraction CvCO2 mixed venous carbon dioxide content [Lgas/Lblood] CcCO2n pulmonary end-capillary carbon dioxide content [Lgas/Lblood] VTCO2n volume [L] of carbon dioxide eliminated by the current, nth, breath delta t n current breath cycle time [min]

The equation above describes the mole balance between the CO2 delivered to lungs (EPBF), the volume taking part in the gas exchange (ELV) and CO2 excreted from the lungs (VTCO2). Normally there is no difference in CO2 between the actual and the preceding breath as the same amount of CO2 as delivered to the lungs as is excreted. When small changes in CO2 concentration are inserted into the equation obtained with short inspiratory or expiratory pauses in three out of nine breaths, nine different equations are obtained. The three unknown variables; ELV, EPBF and CvCO2can be solved with a linear least square optimization, a well-known numerical mathematical principle. The breathing pattern is automatically controlled by the ventilator which provides continuous calculations of EPBF where each value represents the average of the preceding nine breaths and renews with each breath as the newest replaces the oldest in the equation system.

At the day of surgery, included patients arrive 45 minutes earlier than otherwise at the surgical unit. After safe surgical checklist, vital signs are measured and epidural catheter inserted during a light sedation. Patients are anesthetized and muscle relaxed. An endotracheal tube is inserted in the trachea. Central arterial and vein catheters are inserted in sterile conditions with ultrasound guidance. Anesthesia is maintained with propofol in target controlled infusion and a short acting opioid is added as needed.

The protocol in the first 25 patients comprises simultaneous measurements of EPBF and CO at 1) Baseline (three measurments), 2) PEEP 15cmH2O, 3) PEEP 5cmH2O 4) before epidural activation, 5) 10-15 minutes after epidural activation 6) before volume infusion (when the patient is considered hypovolemic by the attending anaesthesiologist) and 7) shortly after volume infusion.

The attending anesthesiologist has the final responsibility on deciding the order of the protocol, for example if volume infusion should precede PEEP 15 cmH20 if hypovolemia is suspected.

The succeeding 10 patients (patients 26 to 35) are PEEP optimized before start of protocol using a standardiazed open lung tool recruitment. During the PEEP elevation (step 2 in the protocol above) 10cmH2O is added to the optimal PEEP and then released back to the baseline optimal PEEP (step 3).

Each comparative measurement of CO and EPBF in the protocol includes as an average of three TPTD measured with PiCCO2 and and the average of EPBF registered in the beginning of the first TPTD and in the end of the last TPTD.

• Study Type: Observational
• Enrollment (Actual): 35

Contacts and Locations

Study Locations

• Sweden
  • Stockholm, Sweden, 17176
    • Karolinska University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Patients having major abdominal surgery requiring advanced hemodynamic monitoring

Description

Inclusion Criteria:

• Elective major abdominal surgery requiring advanced hemodynamic monitoring

Exclusion Criteria:

• Symptomatic coronary artery disease, chronic obstructive pulmonary disease with emphysema

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Only
• Time Perspectives: Prospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Absolute values of EPBF compared to Cardiac output	Mean cardiac output as measured with transpulmonary thermodilution compared to mean effective pulmonary blood flow measured with the capnodynamic method at the start of first thermodilution and during the time interval zero to 4 hours.	Mean CO vs EPBF from zero to 4 hours perioperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in EPBF compared to changes in Cardiac output	Measurement of cardiac output and EPBF as described in Outcome 1 before and after hemodynamic changes.	Mean CO vs mean EPBF from zero to 4 hours perioperatively

Collaborators and Investigators

• Sponsor: Karolinska Institutet
• Collaborators: Region Stockholm
• Investigators: Study Director: Håkan Björne, PhD, Karolinska Institutet

Publications and helpful links

General Publications

• Sigmundsson TS, Ohman T, Hallback M, Redondo E, Sipmann FS, Wallin M, Oldner A, Hallsjo Sander C, Bjorne H. Performance of a capnodynamic method estimating effective pulmonary blood flow during transient and sustained hypercapnia. J Clin Monit Comput. 2018 Apr;32(2):311-319. doi: 10.1007/s10877-017-0021-3. Epub 2017 May 11.
• Sander CH, Sigmundsson T, Hallback M, Sipmann FS, Wallin M, Oldner A, Bjorne H. A modified breathing pattern improves the performance of a continuous capnodynamic method for estimation of effective pulmonary blood flow. J Clin Monit Comput. 2017 Aug;31(4):717-725. doi: 10.1007/s10877-016-9891-z. Epub 2016 Jun 1.
• Sigmundsson TS, Ohman T, Hallback M, Suarez-Sipmann F, Wallin M, Oldner A, Hallsjo-Sander C, Bjorne H. Comparison between capnodynamic and thermodilution method for cardiac output monitoring during major abdominal surgery: An observational study. Eur J Anaesthesiol. 2021 Dec 1;38(12):1242-1252. doi: 10.1097/EJA.0000000000001566.

Helpful Links

• Related Info

Study record dates

Study Major Dates

• Study Start (Actual): October 29, 2015
• Primary Completion (Actual): September 28, 2018
• Study Completion (Actual): December 31, 2018

Study Registration Dates

• First Submitted: January 30, 2018
• First Submitted That Met QC Criteria: February 22, 2018
• First Posted (Actual): February 23, 2018

Study Record Updates

• Last Update Posted (Actual): January 11, 2019
• Last Update Submitted That Met QC Criteria: January 10, 2019
• Last Verified: January 1, 2019

More Information

Terms related to this study

• Keywords: Cardiac output; Carbon dioxide; Intraoperative monitoring; Pulmonary blood flow
• Additional Relevant MeSH Terms: Heart Diseases; Cardiovascular Diseases; Cardiac Output, Low; Cardiac Output, High
• Other Study ID Numbers: CONNIE 1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Undecided

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No