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Trial registered on ANZCTR

Registration number

ACTRN12611000304932

Ethics application status

Not yet submitted

Date submitted

18/03/2011

Date registered

22/03/2011

Date last updated

22/03/2011

Type of registration

Prospectively registered

Titles & IDs

Public title

Detection, quantification and differentiation of upper and lower airway obstruction during mechanical ventilation

Scientific title

Detection of upper and lower airway obstruction in patients with normal lungs and chronic obstructive airways disease and asthma while being mechanically ventilated

Secondary ID [1]

Nil

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Lung Disease
COAD
Asthma

Condition category

Condition code

Respiratory

Other respiratory disorders / diseases

Intervention/exposure

Study type

Observational

Patient registry

Target follow-up duration

Target follow-up type

Description of intervention(s) / exposure

Observation of airways resistance in patients that are mechanically ventilated.
Two groups of patients will be selected, patients with normal lungs and patients with lower airway obstruction(COAD and asthma)
Each patient will be placed on controlled mechanical ventilation, in SIMV and progressively smaller diameter endotracheal tubes will be inserted into the existing endotracheal tube for a period of less than one minute.
Measurements of flow and volume and determination of resistance will be determined.
The patients will have these measurements done within an hour.
The patients will be recruited when they are in intensive care. The recruitment will therefore not be planned. Only when patients are deemed suitable candidates by their existing ventilation will a relative be contacted for consent purposes.

Intervention code [1]

Not applicable

Comparator / control treatment

Patients with normal lungs

Control group

Active

Outcomes

Primary outcome [1]

Determination of airway resistances by analysis of the flow and volume pressure curves from a ventilator. These flow and volumes will be measured after insertion of three progressively decreasing sized endotracheal tubes into already existing endotracheal tubes in an unconscious mechanically ventilated patient.

Timepoint [1]

Immediately after decreasing airway resistance for less than one minute.

Secondary outcome [1]

The above measurements will be analysed to determine the best marker for upper and lower airway resistances.

Timepoint [1]

Analysis after ventilatory waveform data has been recorded.

Eligibility

Key inclusion criteria

Unconscious patients intubated and mechanically ventilated in intensive care.
1 group with normal lungs and 1 group with Chronic obstructive airways disease or asthma

Minimum age

18 Years

Maximum age

99 Years

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

Patients not under mechanical ventilation in the intensive care environment

Study design

Purpose

Screening

Duration

Longitudinal

Selection

Defined population

Timing

Prospective

Statistical methods / analysis

Recruitment

Recruitment status

Not yet recruiting

Date of first participant enrolment

Anticipated

10/04/2011

Actual

Date of last participant enrolment

Anticipated

Actual

Date of last data collection

Anticipated

Actual

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

Funding & Sponsors

Funding source category [1]

Hospital

Name [1]

Intensive care department

Address [1]

The Alfred Hospital
Commercial Road Prahran Victoria 3181

Country [1]

Australia

Primary sponsor type

Hospital

Name

Intensive care department

Address

The Alfred Hospital
Commercial Road Prahran Victoria 3181

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Not yet submitted

Ethics committee name [1]

Research and Ethics Unit

Ethics committee address [1]

The Alfred Hospital
Commercial Road Prahran 3181
Victoria

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

15/03/2011

Approval date [1]

Ethics approval number [1]

Summary

Brief summary

During mechanical ventilation, increased upper airway resistance may be due to a partial obstruction of the
artificial airway or a large airway abnormality. Increased lower airway resistance is usually due to acute or
chronic airways disease. Either of these problems can lead to increased work of breathing, uncoordinated
ventilator support, respiratory distress and difficulty weaning. Recognition of these problems can lead to
important interventions such as bronchoscopy, artificial airway change or reposition, bronchodilator therapy
and change of ventilation strategy that can improve patient distress and safety. Quantification of these
variables can allow assessment of severity and the response to intervention.
Our hypotheses are that
1. the most valuable variable for quantifying reduced expiratory airflow will be the passive expiratory volume
expired during the first second of expiration PEV1 expressed as a percentage of the Vt (PEV1/Vt ratio). This
is similar to the well recognised standard of FEV1/VC ratio from spirometric quantification of (lower) airflow
obstruction.
2. the most valuable variable for quantifying increased inspiratory resistance during VCV with decelerating
inspiratory flow or during PCV will be the difference between the Paw and calculated Palv during early
inspiration divided by the inspiratory flow at that time.
3. Upper airway obstruction will be distinguished from and lower airway obstruction by a higher inspiratory
resistance relative expiratory resistance
We propose to examine these hypotheses in patients with normal lungs with added inspiratory resistances
and in patients with lower airway obstruction (COAD or asthma) to show whether measurements of flow and
volume are independent of or can account for ventilator pattern (flow rate, flow pattern, tidal volume) and can
recognise and quantify both increasing resistances in large (upper) airways and lower airway obstruction to
distinguish between them.
Methods
Two patient groups will be selected based on the following lung pathology
1. Normal Lungs: 20 mechanically ventilated patients with no significant underlying lung disease and no
significant lung injury will be selected.
Each will be studied to provide a normal values of the resistance measurements.
Then each will be given a series of 3 upper airway resistances for a period of less than a minute to mimic
large airway obstruction (similar to a partially blocked endo-tracheal or tracheostomy tube). This will be
achieved by placing a 10 cm sterilized flexible tube in the endo-tracheal or tracheostomy tube to simulate a
residual diameter equivalent to an ETT size (internal diameter) 6, 4.5 and 3 mm. This is little different to and
carries no more risk than routine patient suctioning where the artificial airway is partly occluded to a similar
degree for a short time
2. Lower airway obstruction (COPD, Asthma): 20 mechanically ventilated patients with known obstructive
airways disease (lower airway obstruction)
Each patient group will be placed in controlled mechanical ventilation and given the same series of
ventilatory patterns to determine the reliability of the measurements of inspiratory and expiratory resistance
measurements under different ventilatory conditions

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Address

Country

Phone

Fax

Contact person for public queries

Name

David Tuxen

Address

Intensive Care , The Alfred, Commercial Rd Prahran,
3181
Victoria

Country

Australia

Phone

+61 3 90763036

Fax

+61 2 90763780

davidtuxen1@bigpond.com

Contact person for scientific queries

Name

David Tuxen

Address

Intensive Care , The Alfred, Commercial Rd Prahran, Victoria
3181

Country

Australia

Phone

+61 3 90763036

Fax

+61 3 90763780

davidtuxen1@bigpond.com

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

No additional documents have been identified.

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