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Assessment of Airways Mechanical Properties by Forced Oscillatory Technique (FOT) and Laser Interferometry (LIR) During Anesthesia

The recruitment status of this study is unknown because the information has not been verified recently.
Verified January 2012 by Uppsala University Hospital.
Recruitment status was  Recruiting
Sponsor:
Collaborator:
Politecnico di Milano
Information provided by (Responsible Party):
Peter Kostic, Uppsala University Hospital
ClinicalTrials.gov Identifier:
NCT01506284
First received: December 9, 2011
Last updated: January 4, 2012
Last verified: January 2012
  Purpose

The aims of the present study are:

  1. To evaluate the effect of the induction of anaesthesia and paralysis in terms of changes in oscillatory mechanics parameters
  2. To evaluate the mechanical properties of the respiratory system in terms of input and transfer oscillatory impedance in response to PEEP changes

Condition Intervention
Anesthesia
Procedure: Forced oscillatory technique (FOT) and laser interferometry (LIR).

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: Assessment of Airways Mechanical Properties by Forced Oscillatory Technique (FOT) and Laser Interferometry (LIR) During Anesthesia.

Further study details as provided by Uppsala University Hospital:

Primary Outcome Measures:
  • Change in respiratory system impedance [ Time Frame: baseline and 5 minutes of ventilation ] [ Designated as safety issue: No ]

    FOT measurements:

    Respiratory system impedance will be computed from the flow and pressure signals measured at the inlet of the tracheal tube. A composite waveform including 5, 11 and 19 Hz will be used as a stimulating signal generated by an A/D-D/A board and amplified by a power amplifier that drives a loudspeaker the output of which is connected to inspiratory line of the ventilator.



Secondary Outcome Measures:
  • Change in chest wall displacement measured by LIR [ Time Frame: baseline and 5 minutes of ventilation ] [ Designated as safety issue: No ]

    Laser interferometry (LIR):

    The movement of 18 points of the chest wall will be measured by a self-mixing interferometer. The measurement points will be chosen along three vertical lines (the midline and the two parasternal lines) and will be equally distributed from the clavicles to the anterior superior iliac spines. The chest wall movement will be measured in response to two different stimulating waveforms: a composite waveform including 5, 11 and 19 Hz, a sinusoidal signal at 100 Hz.


  • Change in oxygenation (paO2) [ Time Frame: baseline and 5 minutes of ventilation ] [ Designated as safety issue: No ]
    Arterial blood gas measurement (ABG)

  • Change in Functional residual capacity (FRC) [ Time Frame: baseline and 5 minutes of ventilation ] [ Designated as safety issue: No ]

Estimated Enrollment: 12
Study Start Date: November 2011
Estimated Study Completion Date: November 2012
Estimated Primary Completion Date: July 2012 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
Anesthetized patients ASA I-II
ASA classification I-II, scheduled for elective surgery requiring general anesthesia.
Procedure: Forced oscillatory technique (FOT) and laser interferometry (LIR).

FOT: The stimulating signal is generated by an A/D-D/A board and amplified by a power amplifier that drives a loudspeaker the output of which is connected to inspiratory line of the ventilator. Pressure and flow are measured at the inlet of the endotracheal tube by a piezoresistive pressure transducer and a mesh-type heated pneumotachograph coupled with a differential pressure transducer.

LIR: The scanner unit is made by three laser interferometers, the beams of which are deflected on the chest wall surface by a mirror moved by a stepper motor triggered on the respiratory pattern of patient.


Detailed Description:

It has been recently shown that respiratory system reactance (Xrs) obtained by the forced oscillation technique (FOT) at 5 Hz is more reliable than dynamic compliance for assessing lung collapse and the effects of lung RMs in a porcine ALI model ( Ref.1,2).

Specifically, Xrs (and its derived variable CX5, the oscillatory compliance at 5 Hz) identifies the minimum positive end-expiratory pressure (PEEP) level required to maintain lung recruitment with high sensitivity and specificity. Moreover, it has been recently demonstrated that Xrs may be used to identify the lowest level of PEEP able to prevent atelectasis and that PEEP setting strategy based on maximizing Xrs is able to limit lung injury compared to oxygenation-based approach in a porcine lavage model of lung injury. ( Ref.3)

Recently, at the biomedical engineering department of Politecnico di Milano measurements of chest wall displacement have been successfully performed by means of an optical sensor realized using a laser self-mixing interferometer (LIR). The advantage of this approach is that it is contact-less, that by deflecting the laser been it is possible to scan any region of the chest wall surface and that it allows to measure also low-frequency vibrations.

Protocol

  1. The baseline pulmonary function will be assessed by spirometry before surgery.
  2. Just before surgery measurements of oscillatory mechanics will be performed at the following stages:

    • awake patient
    • spontaneous ventilation through the laryngeal mask after induction of anesthesia
    • pressure controlled ventilation (PCV) after the administration of neuromuscular blocking agent and intubation and PEEP 0 cmH2O
    • PCV with PEEP 5 cmH2O
    • Recruitment maneuver (RM) (peak pressure 30 cmH2O and PEEP 15 cmH2O) for 2 minutes
    • PCV with PEEP 5 cmH2O after RM

At each stage the following measurements will be performed:

  • Input impedance at 5-11-19 Hz by FOT
  • the movements of the chest wall assessed by laser interferometry (LIR) applying two different stimulating waveforms: 5-11-19 Hz and 100 Hz
  • functional residual capacity (FRC)
  • arterial blood gas measurement (ABG)
  Eligibility

Ages Eligible for Study:   18 Years to 80 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Sampling Method:   Probability Sample
Study Population

Patients ASA classification I-II, scheduled for elective surgery requiring general anesthesia

Criteria

Inclusion Criteria:

  • age >18 years
  • ASA I-II, scheduled for elective surgery requiring general anesthesia
  • signed informed consent

Exclusion Criteria:

  • patient refusal
  • BMI > 35
  • co-existing respiratory disease (COPD, asthma, restrictive lung disease)
  • pregnancy
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01506284

Contacts
Contact: Peter Kostic, MD +46186110000 peter.kostic@akademiska.se
Contact: Peter Frykholm, MD, PhD +46186114824 peter.frykholm@akademiska.se

Locations
Sweden
Uppsala University Hopsital, Dep. of Anesthesia and Intensive Care Recruiting
Uppsala, Sweden, 751 85
Contact: Peter Kostic, MD    +46186110000    peter.kostic@akademiska.se   
Contact: Peter Frykholm, MD, PhD    +46186114824    peter.kostic@akademiska.se   
Sponsors and Collaborators
Uppsala University Hospital
Politecnico di Milano
Investigators
Principal Investigator: Peter Frykholm, MD, PhD Uppsala University Hospital
  More Information

Publications:
Responsible Party: Peter Kostic, Principal investigator, Uppsala University Hospital
ClinicalTrials.gov Identifier: NCT01506284     History of Changes
Other Study ID Numbers: Uppsala 2011 - 189
Study First Received: December 9, 2011
Last Updated: January 4, 2012
Health Authority: Sweden: The National Board of Health and Welfare

Keywords provided by Uppsala University Hospital:
Forced oscillatory technique
Laser interferometry
Intravenous anesthesia
Mechanical ventilation
Pressure controlled ventilation
Airways mechanical properties
Respiratory system reactance
Oscillatory mechanics
Atelectasis

Additional relevant MeSH terms:
Anesthetics
Central Nervous System Agents
Central Nervous System Depressants
Pharmacologic Actions
Physiological Effects of Drugs
Therapeutic Uses

ClinicalTrials.gov processed this record on November 25, 2014