Acid base and blood gas analyser


Vocabulary warm-up

1 Match the words in English with their translations:

unknown                                                                        ponořit

inner side                                                                    tenká vrstva

coated                                                                            dosáhnout

immerse                                                                          neznámý

plastic jacket                                                              nylonová síťka

basically                                                                         vnitřní strana

nylon net                                                                     plastikový obal

uncharged molecules                                                                  nenabité
molekuly, molekuly bez náboje

pass through                                                               v zásadě

thin layer                                                                         projít skrz

reach                                                                               tím

thereby                                                           potažený



Reading


1 Read the text and complete the gaps with the words from the box:

Electrode      uncharged      partial     analysers     diffuse     electrolyte     solution


Most acid base and blood gas ___________(1) measure pH, pCO[2], pO[2] by means of selective
electrodes.


pH electrode

A pH electrode is a glass ________(2) with a pH-sensitive glass membrane to seal its tip. On the
inner side of the membrane is a buffer solution with constant pH. A silver wire coated with AgCl is
immersed in this solution and, via a plug, connected to the measuring instrument. On the other side
of the glass membrane is a ___________(3) of unknown pH (the sample).


pCO[2] electrode

pCO[2] is defined as the _________ (4) pressure of CO[2] in a gas phase in equilibrium with the
blood, and is measured by a pCO[2] electrode.


A pCO[2] electrode is a combined glass and silver/silver chloride (Ag/AgCl) reference electrode
mounted in a plastic jacket, which is filled with a bicarbonate_________ (5). The jacket is covered
with a 20 μm silicon membrane moulded on a 50 μm nylon net.


The pCO[2] electrode is basically a pH electrode with a silicon membrane added. This membrane
allows only ___________(6) molecules (i.e. CO[2], O[2], N[2]) to pass through it. Charged ions,
such as H^+, will not pass. Consequently, dissolved CO[2] from the sample will __________(7) into
the thin layer of bicarbonate electrolyte until equilibrium is reached.


2 Now answer these questions:

1 How do the analysers find out about pH, pCO[2 ]and pO[2]?

2 What is the connection between the buffer solution and the measuring instrument?

3 Where is the sample situated?

4 Where can you find the silicon membrane?

5 Which molecules pass through the membrane?






Listening

A Pre-listening warm-up. Put the words in the correct order.

1 blood do a gas

2 sure gloves you have your make on

3 in password put your

4 machine put syringe into the the

5 hit “analyse” button the

6 the for patient ask ID

7 scanner use a

8 it manually put in

9 syringe the remove

10 the sharps syringe in container a discard



B Watch and answer these questions:


1 What is the first thing you should do before running the test?

2 Does the machine require a password?

3 Which type of blood is being tested?

4 How can you read the patients ID?

5 How long does the testing take?

6 How do you know the test is over?

7 How do you get your results?

8 What do you have to do with the syringe?

9 What is the last thing you do?