Dehydration - Pyloric Stenosis

I've probably missed something, but PAP7 seems very similar to dehydration in children. The new bit is pyloric stenosis, also known as hypertrophic pyloric stenosis, which we'll cover here.

Cause
There is hypertrophy and hyperplasia of the two muscular layers of the pylorus. This labels the gastric atrum. The pyloric canal becomes lengthened and the whole pylorus becomes thickened. The stomach may then become markedly dilated.

Associations
First-born white males
Northern European ancestry
Family history (7%)
Bottle feeding
Macrolide antibiotics for infants

Presentation
Pyloric stenosis normally starts in the first 3 weeks of life.
Non-bilious vomiting or regurgitation - projectile in 70% of cases.
The infant is still hungry after feeding and may be jaundiced.
Signs of dehydration and malnutrition.
Firm,non-tender and mobile hard pylorus 1-2cm in the RUQ. Best palpated when vomited and calm. Happens in 60-80%.

Investigations
Bloods:  Severe metabolic alkalosis with partial respiratory compensation
    Hypokalemia

    Hypochloremia
    Hyponatraemic, hypokalaemia --> or maybe higher because of dehydration
Alkaline Urine
AXR: Distended stomach with minimal distal intestinal bowel gas
USS:  Pylorus hypertrophy

Management
NG Tube if vomiting
Fluid resuscitation
Correct electrolyte abnormalities
Nil by mouth
Surgeons for a pyloromyotomy - splitting muscle layer of the pylorus

References
http://us.bestpractice.bmj.com/best-practice/monograph/680.html
http://lifeinthefastlane.com/ccc/pyloric-stenosis/
http://radiopaedia.org/articles/pyloric-stenosis
http://prehospitalmed.com/2013/02/18/levitans-no-desat-with-nasal-cannula-for-infants-with-pyloric-stenosis-requiring-intubation/
http://lifeinthefastlane.com/tag/pyloric-stenosis/
http://pemlit.org/2013/04/13/12th-april-2013-electrolyte-profile-of-paediatric-patients-with-hypertrophic-pyloric-stenosis/
http://emedicine.medscape.com/article/803489-overview
http://www.rcemlearning.co.uk/modules/my-baby-is-throwing-up-and-its-getting-me-down/4
https://www.rcemlearning.co.uk/curriculum/paeds-acute/pap7/

http://broomedocs.com/2013/02/clinical-case-079-is-it-pyloric-stenosis/ may be useful - their server is still down so I haven't read it yet!

Sepsis in Children

Sepsis in children is one of those areas that always frustrates me slightly. In adults, sepsis  care is improving and we have clear criteria for diagnosing sepsis. Diagnosing sepsis in children is a little bit harder - and it can be a fine line between a nasty infection, and sepsis. There are probably three important sections to consider under the "sepsis" banner:

• Fever in children
• Meningococcal septicaemia
• Sepsis identification and treatment 

Mortality from paediatric sepsis ranges from 9% to 35%. Aggressive fluid resuscitation early in the course of SIRS results in decreased mortality. The risk of sepsis is inversely related to age. Neonates are at the highest risk, with bacterial sepsis occurring in 1-10 per 1000 live births in the United States.

Risk Factors
- Children with sickle cell have a 400-fold increased risk of sepsis due to pneumococcus and salmonella.  am
- Severe sepsis 15% more common in boys.

Pathogenesis
In children, shock is more likely to be associated with profound hypovolaemia. They often need more aggressive fluid resuscitation than adults.

Recognition of Sepsis

The NICE traffic light guidelines on feverish illness provide a useful structure for assessing children.
Colour - normal, pale, mottled, ashen or blue?
Activity - responds normally, not responding to social cues, appears ill to an HCP
Respiratory - any signs of respiratory distress?
Circulation - any signs of dehydration?
Other - any amber signs, fever for more than 5 days, swelling of a joint

The college has clear standards for managing sepsis and meningitis in children, and fever in children which will be looked at in more detail when we get to the "fever" section.

Dehydration in Children

 The syllabus is quite vague about dehydration. There are lots of fantastic resources about dehydration including NICE quick reference guidelines (full guidelines), RCH guidelines, Uni of Texas but most of these do focus on dehydration secondary to diarrhoea and vomiting.
There is only one e-learning module I could find on dehydration, but as it was based on a 2010 research paper and lots has changed since then, I didn't complete the module.
EnlightenMe offers a management case on a patient with warning signs for dehydration, where appropriate action was not taken. 

Causes
Worldwide the greatest number of deaths from shock probably occurs in under 5 year old children with hypovolaemia as a result of diarrhoeal illness, and gastroenteritis is still the most common cause in children.

Clinical Assessment
History
The first step to assessing the risk of dehydration is taking a full history.  NICE lists many things as presentations that put people at higher risk of dehydration:
•    children younger than 1 year, especially those younger than 6 months
•    infants who were of low birth weight
•    children who have passed six or more diarrhoeal stools in the past  24 hours
•    children who have vomited three times or more in the past 24 hours
•    children who have not been offered or have not been able to tolerate supplementary fluids before presentation
•    infants who have stopped breastfeeding during the illness


It can be difficult to know how much fluid babies should be taking - and whether their vomiting is a result of over-feeding. Babies slowly increase their intake to 150 mls/kg and this should allow them to gain 20 – 30g weight per day.

Clinical 
There is a nice poster about assessing dehydration here. I've never seen the Gorelick scale used clinically, although the concept is well known. For assessing dehydration in adults, I was taught the mnemonic "HEP B" and I think this works well in children too:
 

When we make our thorough assessment, we decide whether a child is clinically dehydrated or not. If we are using capillary refill we need to ensure we specify where we are checking. Worryingly, all of the standard signs that are quoted have a very low sensitivity and specificity:

NICE Guidelines: http://www.ncbi.nlm.nih.gov/books/NBK63844/pdf/TOC.pdf

None the less, we still use a combination of all these factors to decide how dehydrated a child is. This is very common in exam situations where the child often has sunken dark eyes, and you have to work out their fluid deficit. I think this is a useful reminder to make sure we weigh all children as soon as they arrive in the department, and not just the children who need analgesia or antipyretics.


Biochemical

Do not routinely perform blood biochemical testing.Measure plasma sodium, potassium, urea, creatinine and glucose concentrations if:

• intravenous fluid therapy is required or
• there are symptoms and/or signs that suggest hypernatraemia.

Measure venous blood acid–base status and chloride concentration if shock is suspected or confirmed.

 Treatment
- Oral rehydration is adequate in most circumstances.
  - Oral replacement fluid is best used, even in children with no signs of clinical dehydration.
  - Flat fizzy drinks should not be used. 
- Nasogastric rehydration can be a safe alternative to IV rehydration.

- Fluid bolus of 20ml/kg to treat clinical shock
 Increase up to 40ml/kg as needed
 If any more fluid than this is needed, PICU must be involved.

- Then start maintainence fluids:

1st 10kg - 100mls / kg / day

+

2nd 10kg - 50mls / kg / day

+

Then 20mls / kg / day

e.g. 25Kg = (10 x 100) + (10 x 50) + (5 x 20) = 1.6 litres

Discharge Advice

If you discharge patients home, remember to give them clear advice. The NICE guidelines on D&V are quite clear (although who knew no swimming for two weeks?). 

 - Continue breast feeding and other milk feeds

 - Discourage use of fruit juices and fizzy drinks (until diarrhoea has stopped)

 - Supplement with oral rehydration therapy as needed