Healthcare and Medicine Reference
Insertion and collection is as described for adults in Chapter 7:
the needle will not need to be inserted as far as in adults
collect approximately 5-7 drops per container
use three universal containers for cell count, culture and protein
with one glucose tube.
Remove needle and cover site with plaster when fi nished.
Bleeding (mild), infection (rare).
Suprapubic aspiration of urine
To obtain an uncontaminated urine sample.
Clotting disorders or thrombocytopenia.
Figure 22.9 Filled capillary gas tube. Place bungs on either end and roll the
tube between fi ngers to ensure mixing.
Ideally confi rm that there is urine in the bladder with
Use aseptic technique.
Attach a blue (23G) needle to a 5-mL syringe.
Insert the needle into the abdomen 1 cm above the symphysis
pubis perpendicular to the skin.
Insert the needle to 2-3 cm, aspirating continuously until urine
pH < 7.35
pH > 7.45
Remove needle and cover puncture site with a plaster.
↑ BD/-ve BE
↓ HCO 3
↑ HCO 3
↑ CO 2
↓ CO 2
An alternative sampling method is the in-out catheter. The tech-
nique is the same as for catheterisation except that the catheter is
removed once a urine sample is obtained.
Figure 22.10 Analysis of blood gases. BD, base defi cit; BE, base excess.
Table 22.1 Causes of blood gas abnormalities.
In paediatrics we rarely take arterial blood gases unless the patient
has an arterial line. More commonly we rely on capillary or venous
gases, collected via a capillary tube. This small glass tube is fi lled
using heel or fi nger prick (capillary) or directly from venepuncture.
The sample needs to be free fl owing without any bubbles in the
tube for accurate analysis (Figure 22.9).
Blood gases are interpreted in a similar manner to adults
(see Chapter 6). Be mindful that some of the values will not be
accurate. With venous gases, the pH and HCO 3 results are useful,
but the reliability of the PCO 2 is debatable and should be inter-
preted with caution. Capillary gases are comparable with arterial
gases for PCO 2 , pH and HCO 3 but not PO 2 . See Figure 22.10 for
an introduction to analysing blood gases. Table 22.1 gives some
causes of blood gases abnormalities.
Poor respiratory drive
(e.g. unconsciousness, neuromuscular disorders)
(e.g. asthma, bronchiolitis)
Poor tissue perfusion
(e.g. renal tubular acidosis)
Inborn errors of metabolism
(e.g. organic acidaemias)
Salicylate poisoning (can also cause metabolic acidosis)
(e.g. pyloric stenosis)
(e.g. Bartter's syndrome)
There are several other procedures that would only be expected at
a more senior level in paediatrics and neonatology. These include