electronic supplement material10.1007/s00134... · web view- a face mask specifically...

ELECTRONIC SUPPLEMENT MATERIAL

1. Face masks evaluated

Each of the three face masks evaluated has its own characteristics and is representative

of the current market offers:

- A face mask specifically commercialized as designed to deliver a Helium - Oxygen

mixture: Heliox21® face mask with a non-rebreathing valve, two flap side valves, a

reservoir bag and a Y-piece to possibly connect a nebulizer (Heliox21® nebulizer kit

adult n°1420; Intersurgical, UK).

- A face mask designed to achieve high inspired O2 fractions (FIO2) with low delivered

flow rates: Pulmanex® Hi-OX80 face mask with a non-rebreathing valve, no flap side

valves and a reservoir bag (Ref. 50-8000, Viasys, Netherlands). The Hi-OX80 is

supported by two elastic straps and has a manifold with three one-way valves: one

valve on the inhalation tube, a second valve on the exhalation tube, a third valve which

interconnects inhalation and exhalation tubes. A fourth valve located just beside the

inlet of the oxygen supply hose acts as an anti suffocation valve.

- An adult standard high concentration non-rebreathing face mask for oxygen delivery

(Ref. 106, Unomedical, Italy): this flexible face mask is supported by one elastic strap,

with a non-rebreathing valve, two flap side valves and a reservoir bag. This model or a

similar is the mask the most commonly used for the delivery of high FIO2.

2. Helium-Oxygen mixture delivered

The study product is the inhaled medicinal gas mixture He-O2 , which contains:

- Oxygen 22% ± 1% (Volume)

- Helium 78% ± 1% (Volume).

This gas mixture has been produced and released by Air Liquide Deutschland GmbH

according to standard procedures.

He-O2 78:22 has been supplied by the sponsor in B10 gas cylinders pressured at at 200

bars with a content of ± 2 m3 of gas at 1 bar and 15°C.

A dynabloc (including a pressure reducer and a flow meter) was fitted on the cylinders

to insure a fixed regulation and an easy and adjustable flow on the whole range of the

dial.

3. Devices associated to the measurements

He analyser (Prototype by Viasys, Netherlands)

The method of analysis is based on thermal conductivity.

The specifications of the device were as follows:

- Side stream sampling 200-300 mL/min,

- F[He] measurements: linear between 20 and 80% Helium; response time from

0 to 80 % Helium<800 msec,

- Cross sensitivity of He for O2: +1.5 % He from 21 to 100%

Calibration procedure was performed as follows before the measurements:

- Switch on system and let it stabilise for 15 minutes,

- Switch on computer and start the StampDAQ® program (based on Excel),

- He calibration: let the system acquire and sample room air for zero calibration

(no He in room air); Start recording of data for 10 seconds; Let the system sample via

side port of 2 L/min gas flow from the He/O2 78:22 cylinder; Start recording for 10

seconds; In Excel®, the readings (counts) are then recalculated to calibrate He values.

- Calculation of the calibration factor: sample room air in the device to obtain

Signal 0 (S0) in AD Counts which correspond to 0 % He; sample He/O2 78:22 to obtain

Signal 1 (S1) in AD Counts which correspond to 78% He. As measurements are linear,

the He percentages in between can be extrapolated.

After the measurements were performed, the stability of system was checked as follows:

The gas calibration procedure was repeated to check stability of system. The device was

considered stable if differences between calibration values were below 5%.

Nasopharyngeal sampling catheter

The sampling catheter (Tracheal catheter P/N 10635, 5FR, Viasys, Netherlands) is a

small-bore flexible perforated catheter used originally to measure the pressure in the

endotracheal tube during mechanical ventilation. The small diameter of the catheter and

its flexibility will allow inserting it into the face mask through the lateral side of the

mask. The catheter has been fixed to the nose and cheek by a medical adhesive tape to

avoid its displacement. The catheter has been connected to the He analyser via a heated

capillary line of about 1 meter long (Tracheal catheter adaptor Nº50000-40034, 5FR,

Viasys, Netherlands).

Plethysmograph (Respitrace)

Respiratory rate (RR) and tidal volume (VT), which allowed to calculate minute

ventilation (MV=RR x VT) have been measured and recorded continuously by the

respiratory inductive plethysmograph (Respitrace by Viasys, Netherlands). It is

composed of two bands (one to be placed around the ribcage and the other one around

the abdomen) and a pneumotachometer connected to a differential pressure transducer.

The plethysmograph has been calibrated using the qualitative diagnostic calibration

(QDC) method [1] [2].

SenTec Digital Monitor®

The SenTec Digital Monitor (SenTec, Therwil, Switzerland), placed at the ear lobe, has

been used to monitor continuously, simultaneously and non-invasively the

transcutaneous PCO2 (tcPaCO2) and SpO2 [3].

tcPaCO2 is measured with a Severinghaus type pH-sensitive electrode submerged in

bicarbonate containing electrolytic solution enclosed by a permeable membrane. The

sensor warms up skin temperature to +42ºC to produce capillary hyperaemia. Under this

condition, the membrane allows capillary and skin carbon dioxide diffusion into the

chamber, resulting in a modification of pH proportional to transcutaneous PCO2. The

monitor calculates an estimate of +37ºC corrected arterial PCO2. The sensor is

calibrated after reaching the equilibrium with an external 8% CO2 gas mixture. This

process is automated and takes 5 minutes. In vivo calibration (adjustment to measured

PaCO2) is not available in this device. The system was recalibrated every 8 hr of use.

SpO2 was measured by pulse oximetry using spectrophotometry.

4. Data Collection and Processing

The signal from the He analyser were acquired directly by Acknowledge® program

(Biopac systems, US). The Fp (He) was estimated before the sharp increase in He%,

which was considered as the start of inspiration.

5. Additional results

All statistical analyses were performed using the SAS software version 8.02 (SAS®

Institute, North Caroline, US).

Summary of the average end-expiratory percentage of contamination with room air (% Air Cont). Mean (SD).

Flow rate Ventilatory pattern Heliox 21 Hi-Ox 80 Standard mask

7 L.min-1

Resting 63 (7) 44 (13) 64 (9)Hyperventilation 78 (5) 56 (14) 76 (8)

10 L.min-1


12 L.min-1


15 L.min-1


Summary of average Fp(He)% at end-expiration. Median (Range).


7 L.min-1

Resting 27 (23-37) 48 (27-52) 29 (19-38)Hyperventilation 17 (11-23) 40 (16-43) 20 (9-25)

10 L.min-1


12 L.min-1


15 L.min-1


Summary of average Fp(He)% at end-expiration. Mean (SD).


7 L.min-1


10 L.min-1


12 L.min-1


15 L.min-1


Figure. Median and range of the average Fp(He)% at end-expiration.

Fp(H

e) %

End

-ex

pira

tion

Flow rate (L.min-1)

7

0.2

010 12 15 7 10 12 15

0.4

0.6

0.2

0.4

0.6

Resting pattern Hyperventilation pattern

Heliox 21

HiOx 80

Standard mask

0

10

20

30

40

50

60

70

80

6 7 8 9 10 11 12 13 14 15 160

10

20

30

40

50

60

70

80

6 7 8 9 10 11 12 13 14 15 16

7

80

10 12 15 7 10 12 15

60

40

20

0

80

60

40

20

0Fp(H

e) %

End

-ex

pira

tion

Flow rate (L.min-1)

7

0.2

010 12 15 7 10 12 15

0.4

0.6

0.2

0.4

0.6

Resting pattern Hyperventilation pattern

Heliox 21

HiOx 80

Standard mask

0

10

20

30

40

50

60

70

80

6 7 8 9 10 11 12 13 14 15 160

10

20

30

40

50

60

70

80

6 7 8 9 10 11 12 13 14 15 16

7

80

10 12 15 7 10 12 15

60

40

20

0

80

60

40

20

0

Summary of minute ventilation (L.min-1). Median (Range).


7 L.min-1


10 L.min-1


12 L.min-1


15 L.min-1


REFERENCES ELECTRONIC SUPPLEMENT MATERIAL

1. De Groote A, Paiva M, Verbandt Y, (2001) Mathematical assessment of qualitative diagnostic calibration for respiratory inductive plethysmography. J Appl Physiol 90: 1025-1030

2. Leino K, Nunes S, Valta P, Takala J, (2001) Validation of a new respiratory inductive plethysmograph. Acta Anaesthesiol Scand 45: 104-111

3. Rodriguez P, Lellouche F, Aboab J, Buisson CB, Brochard L, (2006) Transcutaneous arterial carbon dioxide pressure monitoring in critically ill adult patients. Intensive Care Med 32: 309-312

electronic supplement material10.1007/s00134... · web view- a face mask specifically...

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