Assessment of Airways Mechanical Properties by FOT and LIR During Anesthesia

Anesthesia Clinical Trial

Official title:

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

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01506284
• Other study ID #: Uppsala 2011 - 189
• Status: Completed
• Phase: N/A
• First received: December 9, 2011
• Last updated: December 8, 2014
• Start date: November 2011
• Est. completion date: November 2012

Study information

• Verified date: January 2012
• Source: Uppsala University Hospital
• Contact: n/a
• Is FDA regulated: No
• Health authority: Sweden: The National Board of Health and Welfare
• Study type: Observational

Clinical Trial Summary

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

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)

Recruitment information / eligibility

• Status: Completed
• Enrollment: 14
• Est. completion date: November 2012
• Est. primary completion date: March 2012
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years to 80 Years

Eligibility

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

Study Design

Time Perspective: Prospective

Related Conditions & MeSH terms

• Anesthesia

Intervention

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.

Locations

Country	Name	City	State
Sweden	Uppsala University Hopsital, Dep. of Anesthesia and Intensive Care	Uppsala

Sponsors (2)

Lead Sponsor	Collaborator
Uppsala University Hospital	Politecnico di Milano

Country where clinical trial is conducted

Sweden, 

References & Publications (3)

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. — View Citation

Dellacà 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. — View Citation

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. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Change in respiratory system impedance	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.	baseline and 5 minutes of ventilation	No
Secondary	Change in chest wall displacement measured by LIR	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.	baseline and 5 minutes of ventilation	No
Secondary	Change in oxygenation (paO2)	Arterial blood gas measurement (ABG)	baseline and 5 minutes of ventilation	No
Secondary	Change in Functional residual capacity (FRC)		baseline and 5 minutes of ventilation	No