Assessment of Airways Mechanical Properties by FOT and LIR During Anesthesia

NCT ID: NCT01506284

Last Updated: 2014-12-09

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Total Enrollment

14 participants

Study Classification

OBSERVATIONAL

Study Start Date

2011-11-30

Study Completion Date

2012-11-30

Brief Summary

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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

Detailed Description

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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)

Conditions

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Anesthesia

Keywords

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Forced oscillatory technique Laser interferometry Intravenous anesthesia Mechanical ventilation Pressure controlled ventilation Airways mechanical properties Respiratory system reactance Oscillatory mechanics Atelectasis

Study Design

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Study Time Perspective

PROSPECTIVE

Study Groups

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Anesthetized patients ASA I-II

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

Forced oscillatory technique (FOT) and laser interferometry (LIR).

Intervention Type PROCEDURE

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.

Interventions

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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.

Intervention Type PROCEDURE

Eligibility Criteria

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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
Minimum Eligible Age

18 Years

Maximum Eligible Age

80 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Politecnico di Milano

OTHER

Sponsor Role collaborator

Uppsala University Hospital

OTHER

Sponsor Role lead

Responsible Party

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Peter Kostic

Principal investigator

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Peter Frykholm, MD, PhD

Role: PRINCIPAL_INVESTIGATOR

Uppsala University Hospital

Locations

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Uppsala University Hopsital, Dep. of Anesthesia and Intensive Care

Uppsala, Uppsala County, Sweden

Site Status

Countries

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Sweden

References

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Kostic P, Zannin E, Andersson Olerud M, Pompilio PP, Hedenstierna G, Pedotti A, Larsson A, Frykholm P, Dellaca RL. Positive end-expiratory pressure optimization with forced oscillation technique reduces ventilator induced lung injury: a controlled experimental study in pigs with saline lavage lung injury. Crit Care. 2011;15(3):R126. doi: 10.1186/cc10236. Epub 2011 Apr 28.

Reference Type BACKGROUND
PMID: 21575220 (View on PubMed)

Dellaca RL, Andersson Olerud M, Zannin E, Kostic P, Pompilio PP, Hedenstierna G, Pedotti A, Frykholm P. Lung recruitment assessed by total respiratory system input reactance. Intensive Care Med. 2009 Dec;35(12):2164-72. doi: 10.1007/s00134-009-1673-3. Epub 2009 Sep 30.

Reference Type BACKGROUND
PMID: 19789855 (View on PubMed)

Dellaca RL, Zannin E, Kostic P, Olerud MA, Pompilio PP, Hedenstierna G, Pedotti A, Frykholm P. Optimisation of positive end-expiratory pressure by forced oscillation technique in a lavage model of acute lung injury. Intensive Care Med. 2011 Jun;37(6):1021-30. doi: 10.1007/s00134-011-2211-7. Epub 2011 Apr 1.

Reference Type BACKGROUND
PMID: 21455750 (View on PubMed)

Other Identifiers

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Uppsala 2011 - 189

Identifier Type: -

Identifier Source: org_study_id