Developmental Dysplasia of the Hip

Refers to a wide range of pathology- from mild acetabular dysplasia with a stable hip to more severe dysplasia with instability, to established dysplasia with or without subluxation or dislocation.  Usually detected in the neonate.

• It affects 1-3% of newborns.
• Early (post-natal) diagnosis and treatment can reduce the risk of progression and the development of complications
  • When the femoral head is aligned with the centre of the acetabulum, the dysplastic acetabulum often normalises within the first few months of life.  If the hip remains dislocated, soft tissue contractures develop rapidly and surgery may be required
• Left hip is more commonly affected than the right.  Up to 20% are bilateral.
• More common in females (4:1)

Risk factors/Aetiology

• Exact cause is unknown but genetic factors and environmental influences may contribute.
  • Having an affected sibling increases risk by 5%
  • Breech presentation (17-fold; 7-fold if C-section)
  • Large for gestational age
  • Multiple pregnancy
  • Oligohydramnios

Screening and Diagnosis

• Screening takes place within 24 hours of birth, before discharge from hospital, 6 weeks, between 6-9 months, and at walking age.

Barlow test (left) and Ortolani test (right). In the Barlow test (baby’s right hip), the hip is adducted and flexed to 90°; the examiner holds the distal thigh and pushes posteriorly on the hip joint. The test is positive when the femoral head is felt to slide posteriorly as it dislocates. In the Ortolani test (baby’s left hip), the pelvis is stabilised by the examiner and each hip examined separately. In a baby with limited hip abduction in flexion, the hip is flexed to 90° and gently abducted while the examiner’s finger lifts the greater trochanter. In a positive test the femoral head is felt to relocate into the acetabulum. The dislocated femoral head (pictured on the opposite hip) has now been reduced back into joint

• Barlow and Ortilani tests are used post-natally and at 6 weeks to screen for DDH.
  • asymmetry of leg folds
• Late diagnosis
  • Limited hip abduction at 90° flexion; differences in knee height- ‘short thigh’- Galleazzi test (when lying supine at 90/90 flexion); leg length discrepency
  • Problems with walking (NB not usually delayed walking, but trendelenburg gait), painless limp, walking on toes

Investigations

• Ultrasound scans are useful in assessing DDH up until the age of 4-5 months whilst the hips are still cartilagenous.  After this age, radiography is used to assess DDH.
  • There may be a small ossific nucleus of the femoral head (the femoral head densifies in the newborn period- this may not occur in DDH)
  • The joint may have subluxed (disruption of Shenton’s line)
  • A high acetabular index (the angle of the acetabulum to the horizontal line between two hips)

Management

• For children under 4.5-6 months who are Ortolani positive i.e. have a reducible hip, a Pavlik harness is most commonly used
  • Secures the hips in 100° flexion and marked abduction.  It allows the soft tissues of the capsule to strengthen and the tight hip adductors to stretch
• Surgery is usually required for children presenting late (>6 months) and in those who have failed harness treatment (e.g. Ortolani negative)
  • If under 18 months, usually just reduction surgery
  • If >18 months, additional osteotomy may be required

Paediatric Diarrhoea

Background

• Extremely common cause for presentation to either general practice or A&E
• Can be acute or chronic

Taking a history/making a diagnosis/Assessment

• What is the age of the child? What are their vital signs?
  • The younger the individual, the more susceptible to dehydration
    • The biggest risk of diarrhoea in children is dehydration (for assessment and management, see figure below).
      • Make sure to examine for dry mucous membranes, sunken eyes, diminished skin turgor, tachycardia, drowsiness/irritability, deep (acidotic) breathing
  • Fever might suggest infection.  Hypotension may suggest shock and should be treated more urgently (ABCDE)
• Ask about blood in the stool- suggest bacterial infection, ischaemic bowel/infarction, allergic phenomenon or IBD (see below)
• Ask about how much stool is passing and what is its appearance
• Is this acute or chronic?
  • An acute problem is more commonly infective
  • A chronic problem (>2-4 weeks) is more difficult to diagnose:
    • chronic non-specific diarrhoea or Toddler’s diarrhoea (diagnosis of exclusion)
    • lactose intolerance or milk-protein allergy
    • overflow / soiling
    • IBS (also a diagnosis of exclusion but with specific features)
    • Infections
    • Drug induced
    • Inflammatory bowel disease
• Any risk factors?
  • Food changes or risk of contaminated food
  • Does the child go to nursery?
  • Winter months
  • Ill family members
  • Travel
  • Prior surgery
  • constipation
• Any vomiting?
  • Suggests gastroenteritis (infective)
  • **Increased risk of dehydration**
• Any abdominal pain?
  • This is often a more serious sign in children, as it is more common in inflammatory bowel disease, although can also be found in IBS and infective colitis caused by E coli
• Has there been any weight loss or lack of appetite/failure to thrive?
  • This is perhaps the most important question as it will give you the most information as to whether the child requires hospital support or whether they can be managed in the community

TREATMENT for acute infective diarrhoea is mostly supportive and fluid replacement (see above).  Stool samples should be sent in cases of bloody diarrhoea (and/or severe cases) for virology and bacteriology, to further advise management (e.g. public health notification etc)

Differential for the child with chronic diarrhoea

Chronic Diarrhoea Without Failure to Thrive

Chronic Nonspecific Diarrhoea of Childhood or Infancy

• Most common form of persistent diarrhoea in the first 3 years after birth and can last from infancy to up to 5 years.
• Affected children typically pass 4-10 loose stools/day.  No blood, no mucus, no nocturnal bowel movements 
  • first movement is usually shortly after wakening- large formed/semi-formed
  • subsequent bowel movements become smaller, softer, more watery
  • transit time for food can be rapid- often undigested food seen in stool
• Normal weight/height and appetite (maybe mild abdo pain after meals)
• Thought to be due to increased motility and the effect of solutes (particularly carbohydrates e.g. fruit juice) in the gut (increasing osmotic load)
• Normal investigations
• Management is mainly reassurance, perhaps dietary advice (change fruit juices)

Infectious colitis

• Although usually acute, self-limiting presentation, particular strains of infection (most commonly, salmonella) can cause a more protracted course.  E coli can also last over 2 weeks.
  • NB Antibiotic use is not usually indicated in such patients BUT use should be judged on a case by case basis, depending on clinical severity
  • Stool culture- in any case- will aid in this diagnosis

Disaccharide Intolerance (Lactose intolerance)

NB Not the same as milk allergy, which accounts for the majority of cases of milk intolerance in children, although management is the same BUT allergy usually also causes failure to thrive.

• Can be primary lactase deficiency (autosomal recessive- usually family history; can present and persist at any age); secondary (after episode of moderately severe gastroenteritis); congenital (rare autosomal recessive disorder associated with minimal or lack of lactase- apparent once milk is introduced); developmental (seen in premature babies with an underdeveloped gut)
• Can be managed with a lactose free diet

Irritable Bowel Syndrome

• Can be extremely hard to diagnose in young infants- more often becomes clearer in children of late primary/early secondary school age
• Diagnostic criteria
  • abdo pain for at least 3 days per month for the last 3 months PLUS 2 or more of:
    • improvement with defaecation
    • onset associated with a change in bowel habit
    • onset associated with a change in bowel form
  • No weight loss, anaemia, blood, fever etc and all investigations normal
• Management can be difficult- often antispasmodics and/or antidepressants.

Chronic Diarrhoea With Failure to Thrive

Intractable diarrhoea of Infancy

• Persistent diarrhoea after an acute episode of presumed infectious diarrhoea (postenteritis diarrhoea)
• Different from CNSD because there is weight loss, malabsorption and histological evidence of enteropathy
• Can be associated with immunodeficiency, malnutrition and can cause severe problems (does carry mortality)
• Can require TPN- often lipid/protein replacement is more important than carbs- which can worsen diarrhoea
• Refeeding syndrome should be considered as a risk.

Allergic Enteropathy

• Most commonly due to cows milk and soya proteins
• Can be associated with protein malabsorption which may lead to hypoalbuminaemia and diffuse swelling.  Profuse vomiting and diarrhoea may lead to severe dehydrations, lethargy, and hypotension (mimicking sepsis)
• Management is removal of the causal protein

Coeliac disease

• Approximately 1% prevalence
• Reaction to gluten
• Classic triad of failure to thrive, diarrhoea and abdominal distention (although not uncommon to present with other symptom combinations)
• Associated with high anti-tTGA (IgA) antibodies

Inflammatory Bowel Disease

• Children/adolescents suffering from diarrhoea, with or without weight loss, should be evaluated for IBD.
• In crohn’s disease, stool may contain microscopic blood but may not be grossly bloody.  Diarrhoea is more common in colonic disease and may be absent in isolated small bowel disease.
• In UC, diarrhoea is a more common feature, and blood may be present.  Nocturnal diarrhoea and urgency is usually present in left-sided colonic disease.

Other causes of chronic diarrhoea

• Immunodeficiency states e.g. X-linked agammaglobulinaemia, IgA deficiency
• Tufting Enteropathy
• Congenital Secretory Diarrhoea
• Autoimmune Enteropathy
• Microvillous Inclusion Disease
• Neuroendocrine Tumours
• Hirschsprung Disease
• Cystic Fibrosis
• Factitious Diarrhoea

Bronchiolitis

An acute, infectious disease of the lower respiratory tract that occurs, predominantly, in infants between 2 and 6 months old.

Background/cause

• Most commonly viral infection
  • Usually respiratory syncytial virus (RSV- 75%) but also human metapneumovirus (hMPV), adenovirus and parainfluenza virus
  • Around 70% of all babies will be infected with RSV in the first year of life
    • Around 22% develop symptomatic disease
  • Around a third of all infants will develop a bronchiolitis at some point
• One of the biggest causes of infants under one year requiring admission to hospital (around 3% of all infants)- however the majority stay for 1 day
• Peak incidence in the winter months
• Risk factors include: older siblings, nursery attendance, passive smoking, overcrowding
  • Risk factors for worse disease include prematurity & low birth weight, <12 weeks old, cardiac problems, respiratory problems (CF), Down’s syndrome
  • Breast feeding is protective

Presentation

• Coryzal symptoms may be present prior to the onset of severe symptoms
  • e.g. rhinorrhea, cough, mild fever
    • NB high fever >39°C is uncommon and should prompt investigation into other causes.  Similarly, the absence of fever does not exclude bronchiolitisl
    • Cough is usually dry and wheezy
• Other symptoms include problems with feeding, trouble breathing, vomiting irritability
  • Apnoea may also occur, particularly in young infants
• Signs include tachypnoea, tachycardia, respiratory distress (increased work of breathing- using accessory muscles)
  • Upon auscultation of the lungs, widespread fine inspiratory crackles
    • (In the US, more emphasis is put on the presence of an expiratory wheeze)
  • It is unusual for the patient to appear ‘toxic’- i.e. lethargic/irritable – if so, this requires more urgent management for an underlying cause as these patients may dramatically decline
  • Cyanosis is not common but can be a feature

Investigations

• Most investigations are not warranted if a clinical diagnosis is clear
• Viral swabs from nasopharynx are perhaps the only investigation (other than O2 sats) that will be necessary
• Other tests e.g. blood investigations, CXR- are only required if a patient should deteriorate to more severe illness

Management

• Most cases are mild and self-limiting and can be managed at home.
• Patients requiring referral:
  • Poor feeding (<50% of usual intake in 24 hours, or inadequate to maintain hydration)
  • Lethargy
  • History of apnoea
  • Respiratory rate >70bpm
  • Nasal flaring/grunting
  • Severe chest wall recession
  • Cyanosis
  • Saturations <94%
    • NB Threshold for referring should be low in patients with significant comorbidity/premature/young children (<12 weeks)

Paediatric Cardiovascular Examination

As with adult cardiovascular examination, this is based on inspection, palpation and auscultation.  However, because of the differences in the common cardiovascular conditions seen in childhood, the exclusion (i.e. presuming the heart is diseased) of these conditions requires a slightly different approach.

Inspection

• Look for any deformity of the thorax (a bulge might suggest cardiomegaly)
• Look for any peripheral and central signs of cyanosis (hypercyanosis associated with tetralogy of fallot is a paediatric emergency)
• Look for other general signs e.g. pallor, increased work of breathing (take a respiratory rate if this is the case)
• Look for visible palpitations of the heart (this suggests the heart is working too hard)

Palpate

• First, take a radial pulse
• Feel for the apex beat
  • In a young child/baby, this is in the 4th intercostal space, mid-clavicular line.
• Feel for the femoral pulse
  • If possible, do this at the same time
  • If absent, this suggests coarctation of the aorta
• Feel in the sternal notch for a thrill of aortic stenosis
  • Use 3 fingers (outer two on trachea (central) and inner to feel deep in notch for the purr of the murmur)
• Also feel for thrills/heaves of murmurs over the sternal edge (might indicate a right ventricular problem e.g. pulmonary stenosis)

Auscultation

• Auscultate over the apex beat
  • In children, heart sounds (including murmurs) are much easier to hear and so don’t usually require special manoeuvres BUT because of the anatomy of the conditions commonly seen in childhood, any extra sounds should be evaluated further.
• Pansystolic murmur (i.e. loss of HS I+II but murmur in systole)
  • Find the loudest point
    • To do this, auscultate across the chest in an X (i.e. first from left shoulder to right mid-axillary line then vice versa)
    • If loudest at the sternum/centrally- this suggests an AV-septal defect
    • If the loudest at the left lower region, this suggests a mitral valve defect (regurgitation)
• Ejection Systolic Murmur (i.e. HS I+II present)
  • Also find the loudest part
    • If, in combination with sternal notch purr, loudest in the right sternal edge, most likely to be aortic stenosis
      • might also radiate to the carotids
    • If, in combination with a parasternal heave, loudest in the left sternal edge, most likely to be pulmonary stenosis
      • might radiate to the back or infraclavicularly
      • there may also be splitting of the second heart sound
• The Innocent murmur of childhood
  • Still’s Murmur
    • A mid-systolic murmur which has a characteristic low-frequency, musical quality (like a ‘seagull’s cry’)- heard best with the bell
    • Usually loudest at the lower left sternal edge, radiating to the apex/carotids; loudest when the child is supine, is acutely unwell or has been exercising/out of breath (this feature is NOT seen in pathological murmurs)
  • Pulmonary flow murmur
    • Caused by turbulent blood flow in the head and neck veins
    • continuous low-pitched rumbling (can be quite loud)
      • eliminated by lying flat or by compressing the ipsilateral jugular vein
      • loudest usually at upper left sternal edge or infraclavicularly
  • The child will be otherwise normal and healthy- caused by turbulent flow
• Other murmurs
  • Continuous murmurs not relieved by lying/jugular compression may suggest patent ductus arteriosus although these usually also present with bounding or collapsing pulses in infants and young children, respectively

Neonatal physiology and Physiological changes after birth

Respiratory system

Foetal system

• Lungs begin to develop in week 3 of gestation and continue to fully develop by week 16.  Type I and type II pneumocytes are differentiated by 20-22 weeks, and surfactant produced at around 24 weeks.
• Alveolar development continues after birth up to the age of 5 (increasing in number by five times to 300 million).
• During foetal life, the lungs are filled with fluid (amniotic like).  This fluid is compressed from the lung during vaginal delivery.

The first breath

• Factors from the external environment e.g. sound, temperature change, touch etc, stimulate the nervous system to initiate the first breath
  • Central chemoreceptors stimulated by hypoxia and hypercarbia drive further respiration
• Initial breaths require high inspiratory (70-100cmH20) and expiratory (18-115cmH20) pressures to expand the alveoli and to force out amniotic fluid from the airways, respectively
  • This is to overcome the high surface tension
  • Expiration is initially active (i.e. using accessory muscles)
  • The effort required to breathe reduces as fluid leaves the lungs and the alveoli expand.
• In the newborn, the chest wall is more compliant and the lung less compliant (relative to an adult chest)
  • this increases the closing capacity (the volume at which the alveoli collapse) to exceed the functional residual capacity (volume after passive expiration)
    • i.e. alveoli should collapse during breathing – which is not good
  • To overcome this, the newborn creates positive end expiratory pressure in the lungs due to:
    • high-resistance nasal airways
    • partial closure of the vocal cords and glottis
    • post-inspiratory stimulation of inspiratory muscles during expiration
• Newborns have an increased respiratory rate of around 30-60bpm
  • this is to compensate for a decreased inspiratory reserve volume (due to a flatter diaphragm and relatively horizontal ribs) by increasing the minute volume (volume inspired in 1 minute)
    • high resp rate also, in part, compensates for a high metabolic rate

Perfusion/ventilation differences

• The circulatory shunts present in foetal circulation remain present, temporarily, in the newborn.  As a result, the work of breathing in the first week or so of life is increased, but quickly reduces as shunt systems diminish.

Apnoea

• All newborns can have periods of apnoea as their central respiratory drive is immature (improves with age)
  • <5 secs normally
  • premature babies can have prolonged apnoeic episodes (>15 secs) with or without associated bradycardia.

ANAESTHESIA in the newborn can be very risky- physiological PEEP and intercostal muscle tone is lost, reducing the FRC.  Combined with an increased shunt fraction and high metabolic rate, this can cause rapid desaturation.

Cardiac system

Foetal circulation

• Oxygenated blood is preferentially delivered to the brain, myocardium and upper body
  • Facilitated by intra-cardiac (foramen ovale) and extra-cardiac (ductus arteriosus/venosus) shunts
    • Oxygenated blood from the placenta either returns via the liver (~50%) or via the ductus venosus (50% straight to heart via the IVC)
    • The latter is directed through the Eustachian valve and the foramen ovale to bypass pulmonary circulation and supply the head/upper torso.
    • The rest of the (deoxygenated) blood from the liver, SVC, and coronary sinus is preferentially directed to the descending aorta, bypassing the pulmonary system mainly via the ductus arteriosus.
  • Foetal circulation is therefore 2 systems running in parallel- the left ventricle provides 35% of the cardiac output, and the right providing 65%.

Changes at birth

• Umbilical vessels constrict in response to stretching and increased O2 content at delivery.  Clamping of these vessels remove the placenta from circulation and therefore increase systemic vascular resistance.
• Blood flow through the ductus venosus is reduced, causing passive closure over 3-7 days, reducing blood return to the IVC.
• Lung expansion causes a drop in pulmonary vascular resistance and an increase in the return to the left atrium.
  • Combined, the pressures to the right atrium (previously high) and left atrium (previously low) are swapped
  • This causes closure of the foramen ovale within the first few breaths
• The drop in pulmonary vessel resistance and rise in systemic resistance reverses the direction of blood flowing through the ductus arteriosus
  • The ductus arteriosus is thought to diminish as a result of the loss of placenta-derived prostaglandins

  • In babies with hypoxia, acidaemia, structural anomalies etc, the ductus arteriosus may remain patent, which can, in fact, worsen hypoxia (left-right shunting).

Cardiac output

• The high pulse rate (120-160bpm) seen in newborns is mainly to keep up with the high metabolic demand of thermogenesis, feeding, breathing etc.
• As a result, the newborn has a very high cardiac output (200ml/kg/min cf ~80ml/kg/min of adult)
• Following the Frank-Starling law, because of both the high heart rate and immature (stiffer) myocardium, cardiac output is influenced more by heart rate than stroke volume.

Blood

Haemoglobin

• Blood is produced by the liver in utero but is limited to the bone marrow several weeks after birth.
• HbF (α2γ2- higher O2 affinity cf HbA- α2β2) is good in foetal life when O2 needs to be transferred from maternal Hb to foetal Hb at the placenta.  However, at birth, foetal Hb becomes detrimental as oxygen delivery to the tissues is impaired.  This is made worse by increased pH and lower CO2 following delivery.
• HbF accounts for 80% of all Hb in a term baby (can be more in preterm infants)
• Oxygen delivery is facilitated by increased 2,3-diphosphoglycerate (2,3-DPG), which binds to deoxygenated Hb, shifting the oxygenation curve to the right.
• HbF is replaced with HbA by around 6 months
  • However, HbF is lost faster than HbA is produced, leading to a physiological anaemia of infancy at 8-10 weeks

Clotting

• Clotting factors do not cross the placenta.  However, factor V, VIII and XIII are at adult concentrations before birth
• Vit K-derived clotting factors (II, VII, IX, X, protein C and S) are low at birth due to a lack of vit K stores and immature hepatocyte function.
  • Milk is a poor source and endogenous synthesis by gut flora does not occur until several weeks old.
  • Newborns are, therefore, given vit K prophylaxis to protect against haemorrhagic disease.

Thermoregulation

• In utero, the environmental temperature is around body temperature.  At birth, the environmental temperature drops dramatically.  Neonates (particularly preterm) are at high risk of hypothermia
  • 2.5-3 times higher surface area to body mass ratio
  • limited store of subcutaneous fat
  • inability to shiver until 3 months
• Heat can be lost by
  • radiation (39%)- can be reduced by increasing room temperature
    • NB if room temp exceeds body temp, then heat gain will occur.  This can be harmful in preterm babies as sweating for thermoregulation only develops at 36 weeks
  • convection (34%)- can be reduced by warming air and minimising air flow
  • evaporation (24%)- can be reduced by increasing humidity and reducing air flow (in premature babies, a plastic bag/covering can be used)
  • conduction (3%)
• Heat can be generated by
  • limb movement
  • stimulation of brown fat

Hepatic function

• Enzyme pathways take around 3 months to activate
  • Including conjugation pathway for bilirubin (activates around 2 weeks)
    • Because of this- unconjugated bilirubin levels tend to rise within first 48 hours due to HbF breakdown and lack of hepatic function
    • This can be exacerbated by haemolysis, sepsis, dehydration etc
    • Neonatal jaundice is common, but bilirubin levels should stabilise within 2 weeks

Renal Function

• Whilst all nephrons are usually present at birth, immature blood flow limits the concentrating ability of newborns (about half the capacity of an adult), and there is a low GFR (20-40).
  • These increase to adult levels by the age of 2
  • Make the baby more susceptible to both dehydration and fluid overload.
• However, this enables the baby to counteract the effect of parathyroid hormone (phosphate loss) which increases after birth to help increase calcium levels needed for growth

Body Fluid

• At birth in a term child, around 75% of total body weight is water (compared to 50-65% of normal adult)
  • Preterm babies can have significantly higher total body water composition (around 80-85%)
• Around 40% of a newborn baby’s fluid is extracellular (compared to 30% in normal adults)
  • In preterm infants the distribution is around 65% ECF and 35% ICF
• For the first 12-24 hours of life, urine output is limited to 0.5ml/kg/hour due to poor renal perfusion.  Once the cardiovascular system has fully adapted, the kidneys begin to excrete excess sodium (and ECF)- natriuresis.
  • Causes a steady weight loss for the first 5 days of life (1-2% of body weight) and reduces the ECF to ‘normal’ 30%

Fluid requirements

• Fluid replacement should be considered in
  • premature infants in whom there is concern about fluid balance
  • babies with respiratory failure/distress
  • surgical babies
  • babies with excessive urinary losses (inc. renal failure, caffeine and diuretics)
  • consider carefully in phototherapy
• Insensible fluid losses in the newborn equal around 12ml/kg/day, though this can vary with the environment
  • 25-week old infant may be losing up to 15× this ammount
• Losses from the stool are also higher in newborns at aroun 5ml/kg/day
• Any fluid replacement in neonates must take into account the natriuresis that occurs within the first few days of life
  • Sodium should not be given in the first two days of life(to avoid hypernatraemia/fluid overload)
  • Potassium is also not required in the first 1-2 days of life, but can be prescribed thereafter depending on serum potassium levels
    • 4.5-5.5: 1mmol/kg/day; 3.5-4.5: 2mmol/kg/day; 2.5-3.5: 3+ mmol/kg/day; <2.5: 4+mmol/kg/day
    • Hyperkalaemia >7.5mmol/l should be treated with bicarbonate/calcium chloride
  • 10% dextrose is preferred and should be given
    • 60-80ml/kg/day for the first few days (more in low birth weight babies)
    • Increasing by 10-25ml/kg/day until 1 week- 150ml/kg/day in the first week in term infants (higher in pre-term)

Nutrition

• In utero, most nutrition comes from the placenta, although the gut is formed usually by 25 weeks (around 0.3g/kg/day of protein is provided from swallowed amniotic fluid)
  • In the last 6 weeks of gestation, fat deposition increases (by almost 2 fold) and glycoogen stores increase (to 9-times that of adult) to try and prepare for change at birth
    • Thus this can be a huge problem for preterm infants, given the high energy requirement for growth and thermal regulation
• At birth, high levels of catecholamines initiate glycogenolysis, lipolysis and gluconeogenesis.
  • glucose stores are low 2 hours post-delivery
  • glycogen stores depleted around 12 hours post-delivery
  • infants then begin to break down fat until enteral feeding
    • Neonates need nutrition to gain weight and prevent metabolic starvation which may cause developmental delay

Neonatal Brachial Plexus Palsies

Background

• The brachial plexus supplies signals from the spine to the shoulder, arm and hand.  Damage to these nerves as a baby is a relatively common complication during birth (particularly difficult vaginal deliveries; rarely in C-sections)
• Occurs in around 0.5-2/1000 births
• Erb’s Palsy affects C5/C6 (much more common) whereas Klumpke’s Palsy affects C8/T1
  • In severe cases, total brachial plexus palsy will affect C5-T1

Causes and Risk Factors

• Over 50% are associated with shoulder dystocia
  • Shared risk factors e.g. macrosomia, diabetes, obesity etc
• Erb’s palsy
  • Lateral traction exerted on head/neck during delivery in vertex position
  • Arm extended overhead in breech position
  • Excessive traction placed on shoulders during delivery
• Klumpke’s palsy
  • Much rarer but thought to be mainly due to traction of the arm in an abducted position

Presentation

Erb’s palsy

• Unable to abduct the arm from the shoulder, externally rotate the shoulder, supinate the forearm
  • As a result, the child will often have a relatively immobile, adducted, internally rotated shoulder and a pronated, extended elbow (waiter’s sign)
  • C5 supplies
    • axillary nerve
      • deltoid, teres minor
    • suprascapular nerve
      • supraspinatus, infraspinatus
    • musculocutaneous nerve
      • biceps
  • C6
    • radial nerve
      • brachioradialis (supinator)
• There are also loss of the moro reflex and biceps reflex

Klumpke’s palsy

•  Deficit of all of the small muscles of the hand
  • presents as ‘claw hand’
    • wrist in extreme extreme extension due to unopposed wrist extensors
    • hyperextension of MCPs due to loss of intrinsics
    • flexion of the IP joints due to loss of intrinsics
  • Main nerves affected are the ulnar and median nerves
• Involvement of T1 may present also as a Horner’s syndrome
  • this has a worse prognosis

Investigations

• These routinely don’t require investigations but MRI may be useful in assessing the nerve root damage

Management

• The mainstay of treatment is conservative: intermittent immobilisation (in abduction and external rotation, supination and wrist extension) and passive exercises to prevent contractures
• Surgery (nerve repair/grafting) may be done if
  • complete flail persists for a month
  • a Horner’s syndrome for a month
  • persistent symptoms (particularly biceps function) at 3-6 months
• Klumpke’s palsy has a worse prognosis (as does total brachial palsy)

Shoulder dystocia

A vaginal cephalic delivery that requires additional obstetric manoeuvres to deliver the foetus after the head has delivered and gentle traction has failed.

• It results from either the anterior, or less frequently the posterior, impacting on the maternal pubic symphysis, or sacral promontory, respectively.

Background

•  Occurs in 0.5-0.8% of vaginal deliveris

Risk factors/Aetiology

• Poor contractions during labour / prolonged labour (e.g. secondary arrest)
  • Primigravida (1st child) may be more at risk because of this.
• Transverse/Breech baby
• Macrosomia
• Maternal Diabetes
• Maternal Obesity (BMI >30kg/m)
• Induced labour and oxytocin prescribing during labour
• Assisted vaginal delivery e.g. forceps or ventouse

Prevention measures

• Mothers with pre-existing or gestational diabetes should be offered induced delivery at 38 weeks (with or without macrosomia)
  • NB Induction should NOT be offered to non-diabetic mothers with macrosomia
• Previous shoulder dystocia does not necessarily indicate C-section in the future- decision should be made jointly with woman and the obstetric team

Recognising Shoulder Dystocia

• It is important to recognise the features of dystocia early and to get help early
• Some features may include
  • difficulty with delivering the face/chin
  • the head remaining tightly applied to the vulva or even retracting (turtle-neck sign)
  • failure of restitution of the head (rotating in line with the shoulders)
  • failure of the shoulder to descend
• ‘Normal’ traction (i.e. not more than would be used in a normal vaginal delivery) applied in the axial plane (in line with the spine) may be used to diagnose dystocia
  • Normally, the baby would progress with traction.  In shoulder dystocia, it won’t.

Management

• Stop the mother pushing
• McRoberts’ Manoeuvre
  •  the patient hyperflexes her hips so they are against her abdomen. Mothers in labour may not have enough energy to do this by themselves and may need the assistance of others in the room – which is usually the case. Posterolateral pressure is applied suprapubically with traction on the fetal head. This is the most effective procedure and should be performed first (success rates are up to 90%)
• If this does not work, episiotomy (cut between the vagina and anus) may be required and other manoeuvres attempted
  • e.g. Rubin’s and Woods’ screw, which involve pressing on the posterior shoulder and turning the anterior shoulder posteriorly, respectively
• Caesarean section should also be considered early on as a management if there is no response to McRoberts’ manoeuvre
• NB DO NOT APPLY FUNDAL PRESSURE as this may rupture the uterus.

Complications

• Brachial plexus palsies
  • Occurs in 2.3-16%.  90% of BPPs resolve without permanent disability.
• Postpartum haemorrhage (11%)
• Tearing
• Perinatal morbidity/mortality from hypoxia/acidosis

Overdoses

Poisoning is the administration of a substance, taken internally or externally, that is injurious to health/dangerous to life.

Overdose is the use of a quantity of drug in excess of its intended or prescribed dose, and is a major cause of poisoning.

Both can be accidental or deliberate and both can involve legal, prescribed, non-prescribed and illegal compounds.

Epidemiology

• Acute poisoning occurs in 200 per 100,000 of the population in the UK every year (In Tayside, this figure may in fact be closer to 400/100000).  Poisonings account for 100,000 admissions each year.

Paracetamol Poisoning

• Can occur intentionally or accidentally and can occur in any age group, including young children.
• The recommended maximum dose of paracetamol is 1g every 6 hours (i.e. 2 500mg tablets, 4× a day).
• A toxic dose of paracetamol usually varies with weight:
  • minimum toxic dose is commonly quoted as 150mg/kg (~9-10.5g per day)- anything over this is likely to cause liver function abnormalities
  • anything above 250mg/kg is likely to cause severe liver damage (~16-20g per day) and may be fatal

Pharmacodynamics/Pathophysiology

• Well absorbed in stomach- reaches peak plasma concentration by around 30 mins-1 hour.
• It is inactivated by the liver normally by conjugation, resulting in two metabolites: glucoronide or sulfate, which is excreted by the kidneys
  • In acute overdose- it is actively metabolised by the cytochrome system into the toxic metabolite: N-acetyle-p-benzoquinoneimine (NAPQI)
  • This is then conjugated with glutathione and excreted
  • Once glutathione stores are depleted, NAPQI causes damage to the liver (free oxygen radicals)
• Previous induction of the cytochrome P450 system with alcohol or other drugs (e.g. rifampicin, phenytoin, carbemazepine) may increase the toxicity of paracetamol

Clinical Presentation

• IT IS IMPORTANT TO ASK WHEN THE OVERDOSE WAS TAKEN
• Within 24 hours, most are asymptomatic
  • Some may report nausea/vomiting
• 24-72 hours, patients may develop RUQ pain, nausea, vomiting and anorexia.
  • Can also develop oliguria, hypoglycaemia, renal failure (day 3+), lactic acidosis
  • jaundice and liver failure occurs around 3 days + too, and may also present with a liver flap, tenderness and/or encephalopathy
• The patient may be anxious, have low mood

Investigations

• Paracetamol level should be measured IF 4 HOURS HAVE PASSED-
• 
• FBC, U&Es and LFTs may be useful to assess the toxicity. Glucose and clotting are also useful

Management

• N-acetylcysteine
  • If taken within 8 hours, is very effective at minimising the complications
  • Usually given as 3 infusions run without a break
    • 1st- 150mg/kg- 1 hour; 2nd- 50mg/kg- 4 hours; 3rd- 100mg/kg- 16 hours
  • Currently no contraindications to NAC treatment- should be started regardless

Opioid Poisoning

• Most commonly occurs with illicit drug use, community prescribed overdose (intentional or accidental) or at the in-patient level (over-use of opioids to treat pain)

Presentation

• Depressed level of consciousness, respiratory depression and pinpoint pupils (miosis) is the classical triad of symptoms.
  • Nausea/vomiting are also common and may be an early sign; as can erythema caused by vasodilation caused by histamine release (often dose-dependent)
  • However, euphoria/abnormal behaviour may also be a sign
    • Whilst these patients may not have severe toxicity warranting antagonist treatment, the dose of opioid they are taking should be reduced/stopped
  • If the patient is an IV drug user- signs e.g. track marks, may be apparent

Management

• ABCDE
• Naloxone is a μ-receptor antagonist
  • Has a stronger affinity for the receptor than opioids so will rapidly reverse the effects of opioids
  • It is very safe (few side effects) BUT the consequences of rapid opioid removal must be considered
    • In chronic IV users, consider a slow infusion where possible, as rapid correction may precipitate withdrawal symptoms
    • In post-op patients (or patients on opioids for pain management)- pain must be addressed.  Naloxone may be necessary but will render the use of opioid drugs ineffective for several hours
      • ?use other pain medications or possibly try a slow infusion/low dose naloxone
      • NOTE: the half-life of naloxone is still shorter than most opioid analgesics and illicit drugs and so multiple dosing may be required.
  • Naloxone comes in 0.4mg ampoules and should (ideally) be given IV (can be IM)
    • Consider 0.2mg if more appropriate.  Alternatively, if toxicity is very severe, increase up to 4mg if necessary.
• In any case, these patients require close monitoring to their response.

Beta-blockers

• Again, can be intentional or accidental
• Beta-blockers reduce heart rate, blood pressure, myocardial contractility and myocardial oxygen consumption (all β-1) and inhibit smooth muscle relaxation in the vessels, bronchi and GI/GU tracts.  Can also inhibit glycogenolysis and gluconeogenesis, and can result in hypoglycaemia.
• Patients who have overdosed typically present with marked bradycardia, hypotension, reduced resp rate, reduced level of consciousness, pallor
  • can present with seizures and/or prolonged QT
• Treat with Glucagon +/- ionotropes/chronotropes

TCAs

• >10mg/kg is potentially serious and >30mg/kg usually causes severe toxicity and coma lasting >24 hours
• The toxic effects are the result of
  • Inhibition of noradrenaline and serotonin reuptake at nerve terminals
  • Anticholinergic action
    • sedation/coma precede cardiac effects
    • delirium
    • urinary retention, dry skin/mucous membranes
  • Direct alpha-adrenergic blockade
    • this can cause profound hypotension
  • Membrane stabilising effect on the myocardium by blocking the cardiac myocyte fast sodium channels
    • this latter effect can widen the QRS complex, although this usually is a later sign.  More commonly is a sinus tachycardia.
  • Can result in a metabolic acidosis too
• It is treated with sodium bicarbonate 
  • Treat to target pH 7.5-7.55 and replace potassium if hypokalaemic.

Aspirin

• 125mg/kg is minimum toxic dose; >250mg/kg is likely to cause toxicity; >500mg/kg likely to cause severe/fatal toxicity
• Mild / Stage I
  • Nausea, vomiting, tinnitus, lethargy, dizziness /
  • blood pH >7.4, urine pH >6, respiratory alkalosis, increased urinary excretion of bicarbonate
• Moderate / Stage II
  • Hyperventilation, confusion
  • blood pH >7.4, urine pH <6, metabolic acidosis with compensating respiratory alkalosis, urinary hydrogen excretion, intracellular potassium depletion
• Severe / Stage III
  • Tachypnoea, deafness, hallucinations, seizures, coma, cerebral/pulmonary oedema
  • blood pH <7.4; urine pH <6; severe metabolic acidosis and hypokalaemia
• Treat with charcoal, rehydration, glucose and potassium as required.  Urinary alkalisation with bicarbonate as with TCAs.

Benzodiazepines

• Rare but can occur
• Can cause dizziness, confusion, drowsiness, blurred vision etc (excess sedation) but can also cause paradoxical stimulation (anxiety, agitation)
• There is an antidote (Flumazenil) BUT supportive treatment is preferred as flumazenil will competitively bind to the BZD receptor and may precipitate withdrawal  or seizure symptoms which may, in fact, be worse than overdose