najla wrote:

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if patient is receiving for example 2 L o2 via nasal canulla how calculate percentage o2 equivalent to?

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Was this also a question in the exam ?

Here is an answer

But this is too complicated

The wards have charts to give the percentages

This book on the web gives sych a chart

http://books.google.co.uk/books?id=n0ye-tRYTNkC&pg=PA487&lpg=PA487&dq=calculate+oxygen+delivery+masks+cannulae&source=bl&ots=Aq5PJmqZ_O&sig=cJQW2HgW3LyTKr7PYTbMZbwD1Ew&hl=en&ei=z62sSqWjCcnPjAfzybXuBw&sa=X&oi=book_result&ct=result&resnum=1#v=onepage&q=&f=false

 

 

Box 1. Calculating the inspiratory

oxygen fraction (FIO2) delivered by

nasal prongs

Flow of oxygen to nasal prongs

= 4 L·min-1 (67 mL·s-1).

Breathing frequency = 20 min-1.

Tidal volume = 500 mL.

Inspiratory:expiratory time ratio 1:2

(= inspiratory time of 1 s).

Size of the anatomical reservoir of the

nose = 50 mL.

Inspiration comprises 50 mL pure

oxygen (anatomical reservoir) + 67

mL pure oxygen (nasal prongs) +

ambient air: 117 mL oxygen (FIO2

1.0) + 383 mL air (FIO2 0.21) = FIO2

of ~0.4.

of eyeglasses (for example the socalled

Kickinger Brille, Germany)

for cosmetic reasons (fig. 2).

A newly developed device, the

Vapotherm 2000i (Vapotherm,

Annapolis, MD, USA) is a high-flow

gas delivery device that heats and

humidifies gas for delivery through

a nasal cannula, face mask,

tracheostomy or other common

respiratory appliance.

The Vapotherm 2000i contains a

high-flow cartridge that is rated

for 540 L·min-1 at 95% relative

humidity and a high temperature

(3343°C). The temperature and

humidity are preserved during

flow through a special tube that is

warmed by water so no

condensation takes place

(fig. 3).

The exact mechanism by which these

devices provide a better oxygen

supply than a normal nasal cannula

with the same oxygen flow has not

been fully elucidated. There are

several possibilities: the warmth, the

humidity or the high flow.

Theoretically, high-flow anhydrous

gases could cause the resistance of

the nasal passage to rise, or

discomfort with dry gases could lead

the patient to switch to pure mouth

breathing, resulting in a lower FIO2.

Due to the high costs of this device, it

is not appropriate for home care, but

it may be useful for oxygen supply in

severely ill patients with high oxygen

demand, for example with end-stage

idiopathic pulmonary fibrosis

patients listed for lung

transplantation.

Transnasal catheter

In the hospital, a variant of the nasal

cannula is sometimes used the

so-called transnasal catheter (fig. 4).

This catheter is introduced into one

nasal passage and fixed in the

nostril with foam rubber

surrounding the tube. The

anatomical reservoir (naso- and

oropharynx) is about double the size

of that used by the nasal cannula.

The FIO2 is higher compared with

the nasal cannula and is in the

range 0.30.55. The calculation is

shown in Box 2.

Box 2. Calculating the inspiratory

oxygen fraction (FIO2) delivered by the

transnasal catheter

Flow of oxygen to transnasal catheter

= 4 L·min-1 (67 mL·s-1).

Breathing frequency = 20 min-1.

Tidal volume = 500 mL.

Inspiratory:expiratory time ratio 1:2

(= inspiratory time of 1 s).

Size of the anatomical reservoir

= 100 mL.

Inspiration comprises 100 mL pure

oxygen (anatomical reservoir) + 67 mL

pure oxygen (nasal prongs) + ambient

air: 167 mL oxygen (FIO2 1.0) + 333 mL

air (FIO2 0.21) = FIO2 of ~0.47.

Flow of oxygen to transnasal catheter

= 6 L·min-1 (= 100 mL·s-1).

Other parameters as before.

Inspiration comprises 100 mL pure

oxygen (anatomical reservoir) + 100 ml

pure oxygen (nasal prongs) + ambient

air: 200 mL oxygen (FIO2 1.0) + 300 mL

air (FIO2 0.21) = FIO2 of ~0.52.

07 DEVICES FOR OXYGEN ADMINISTRATION DURING SPONTANEOUS BREATHING

76

Practically everybody uses one of these charts -like the one in the book to which I gave a link
No one has ever told me about a question like this before

What was the wording ?
Was it 2L of oxygen via nasal cannula and a list of options of the percentages ?