10. Paeds Flashcards
Kids in status algoriddim
Status epilepticus is defined as convulsions lasting for 5 or more minutes or recurrent episodes of convulsions in a 5-minute period without return to pre-convulsive neurological baseline. A typical secondarily generalize tonic-clonic seizure generally stops by three minutes and almost always by 5-minutes. Status epilepticus was previously defined as continuous seizure activity of at least 30 minutes duration or intermittent seizure activity of at least 30 minutes duration during which consciousness is not regained. In approximately one-third of cases it is the first presentation of epilepsy.
In 2011, the Advanced Life Support Group published a new guideline for the management of status epilepticus in children. The management varies according to the presence or absence of intravenous or intraosseous access.
In all cases the first priority is to establish a patent airway, give high-flow oxygen and ensure blood glucose levels are checked and corrected if needed.
Step 1 (Five minutes after start of seizures):
Many children may have already undergone step 1 before arrival at hospital and it is important to remember this. If intravascular access is available then initial treatment is lorazepam 0.1 mg/kg IV If no intravascular access then give buccal midazolam 0.5 mg/kg or rectal diazepam 0.5 mg/kg. Step 2 (Ten minutes after start of seizure):
If the convulsions continue give a second dose of benzodiazepine, call for senior help and start to prepare phenytoin No more than two doses or benzodiazepines should be given (including any doses given before arrival at hospital) If still no IV access then obtain intraosseous access (IO). Step 3 (Ten minutes after step 2)
Senior help along with anaesthetic/ICU help should be sought
Phenytoin 20 mg/kg IV over 20 minutes
If the seizure stops before the full dose of phenytoin is given then the infusion should be completed as this provides up to 24 hours of anticonvulsant effect
In children already receiving phenytoin as treatment for epilepsy then an alternative is phenobarbitone 20 mg/kg IV over five minutes
Once the phenytoin is started, senior staff may wish to give rectal paraldehyde 0.4 mg/kg although this is no longer included in the routine algorithm recommended by APLS.
Step 4 (20 minutes after step 3)
If 20 minutes after starting phenytoin the child remains in status epilepticus then rapid sequence induction of anaestheisa with thiopentone and a short acting paralysing agent is needed and the child transferred to paediatric intensive care.
`Neonates
Hb at birth
Hb at 3/12
1 year
Basal oxygen consumption ml/kg/min
how many that of times adult
If 3kg what would be
What is the surface are to body weight ratio vs adults
Are they homeothermic
how is brown fat controlled
At birth the haemoglobin concentration is about 180 g/L, and this rises slightly in the first few days as excess extracellular fluid is removed. By the age of 3 months the haemoglobin concentration has fallen to 100 g/L (physiological anaemia of infancy), and by one year it should be 120 g/L.
The basal oxygen consumption of a neonate is 7-8 ml/kg per minute, which is 2-3 times that of an adult (if the birth weight was 3 kg, then the oxygen consumption would be 21-24 ml/min, not 150 mL).
The surface area:body weight ratio of a neonate is around twice greater than that of an adult (not four times greater). Together with reduced subcutaneous adipose tissue and immature heat producing mechanisms (for example, shivering), they are particularly susceptible to heat loss and hypothermia.
Neonates are homeothermic and vasoconstrict in response to cold.
There is also an increase in triglyceride metabolism in brown fat stores, which is under sympathetic nervous system contro
What happens when umbilcal cord clamped
what does this to do to ductus
When lungs aerated what happens pvr
What happens with PDA
When the umbilical cord is clamped, the umbilical vein closes, systemic vascular resistance is increased and this causes the ductus venosus to close.
At birth the lungs are aerated, acutely lowering the pulmonary vascular resistance.
The ductus arteriosus usually constricts in a response to the rising oxygen tension, thus preventing the blood from the aorta and pulmonary artery from mixing (left to right shunt). There is no opening between the two ventricles.
The foramen ovale is the anatomical opening between the right atrium and left atrium that closes shortly after birth.
The cardiac output for an adult is 5 litres a minute.
Childs weight estimation
The formula for estimating a child’s weight is (age + 4) × 2. It is the preferred formula used by The Royal College of Anaesthetists in the Primary FRCA examinations.
Weight=3(age)+7’ provides a mean underestimate of only 6.9% this formula remains applicable from 1 to 13 years inclusive.
How many autosoma chromosomes
how many chormosomes in gnerminal cells
Are both X active in females
Klinefelters changes
There are 22 pairs of autosomal chromosomes and one pair of sex chromosomes.
Due to meiosis, only 23 chromosomes are found in the germinal cell.
Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in cells other than egg cells.
In Klinefelter’s syndrome, the male cell has an extra X chromosome.
The Barr body is due to inactivated X chromosom
Acute epiglottitis
what age group
what organism
Look
It is important not to disturb or upset the child as this may precipitate total airway obstruction and death.
Epiglottitis is most common in the 1 to 6 year age group and is most commonly caused by Haemophilus influenzae type B.
The patient usually looks toxic and has a high fever.
What is thge dead space ratio in kids vs adults
where is the narrowest part of the airway in adults & kids
What is airway resistance in children
what is compliance in lungs
what is mv in kids
The dead space ratio, whatever the age, is 0.3. It is the ratio of dead space (Vd) to tidal volume (Vt).
The narrowest point of the upper airway in the adult is the glottis; in a child it is the cricoid ring.
Airway resistance in a child is much higher than an adult. The smaller diameter of a paediatric airway increases the resistance to airflow. Airway resistance is inversely proportional to radius (r) to the power of 4 (r4). Paediatric patients are therefore prone to the changes to airflow resulting from a small reduction of airway diameter, for example, by oedema.
The compliance of the lungs of a newborn is very low 5 mL/cmH2O but progressively increases as lung size and elasticity increases. The adult value of lung compliance is 200 mL/cmH2O.
The minute ventilation (mL/kg/minute) is much higher in children.
Neonatal CVs function
How do they increase CO
What is systolic bp at term
PVR at birth
Compliance lungs TV
Closing volume
Increases in cardiac output are dependent on changes in heart rate, as the capacity to increase the stroke volume is limited.
The average systolic blood pressure in a full term neonate is about 80 mmHg.
The pulmonary vascular resistance is high at birth but then falls rapidly in the first few days. In the fetal circulation the high pulmonary vascular resistance results in blood being diverted into the systemic circulation via the ductus arteriosus.
The ductus arteriosus usually fibroses within 4 weeks of birth.
At birth the lung compliance is low and the chest wall compliance is increased. The tidal volume is relatively fixed and so increasing the alveolar ventilation is achieved mainly by an increase in respiratory rate (not tidal volume).
Closing volume is increased during the neonatal period (not low), due to a reduction in chest wall recoil. The functional residual capacity is also low.
In utero shunts
how man
Connecting what to what
At birth what happens
what happens to PVR * blod flow
what does this pressure difference do to Foramen ovale
DA closes when
in response to what
The first cardiac shunt to close functionally at birth is the foramen ovale in response to a reverse in pressure gradient between the right and left atria.
Before birth the three important cardiac shunts in-utero are:
The connection between left and right atria - foramen ovale
The connection between the truncus arteriosus and the aorta - ductus arteriosus, and
The connection between placenta and inferior vena cava - ductus venosus.
At birth the reactive umbilical vessels constrict in response to stretch and they are then clamped.
Blood flow falls through the ductus venosus (DV) causing a reducing venous return to the heart. The DV closes passively in 3-10 days.
There is a dramatic fall in pulmonary vascular resistance and an increase in pulmonary blood flow. The increase in pulmonary blood flow increases flow and pressure in the LA that exceeds that of the right atrium. This difference in pressure normally leads to the immediate closure of the foramen ovale.
The DA closes functionally within the first 36-hours of birth. Initially it constricts in response to high PaO2 and a fall in prostaglandin E2. Subsequent endothelial and fibroblast proliferation leads to anatomical closure.
Oxygenated blood from the placenta passes to the liver via the umbilical vein. Blood also bypasses the liver via the ductus venosus into the inferior vena cava (IVC).
The Eustachian valve (Crista dividens) is a tissue flap situated at the junction of the IVC and the right atrium (RA). This flap directs the more highly oxygenated blood, streaming along the posterior aspect of the IVC, across the foramen ovale into the left atrium (LA).
How does oxygenated blood reach the fetus
What is the path it takes
WHere is the higher oxygenated blood pass
Where is this delivered to
Oxygenated blood reaches the fetus via the umbilical vein (PaO2 4.7kPa; SaO2 80-90%). Up to 60% of this blood flow bypasses the liver in the ductus venosus (DV) which then becomes the inferior vena cava (IVC).
At the junction of the IVC and the right atrium (RA) a tissue flap (Eustachean valve) directs the more highly oxygenated blood, streaming along the dorsal aspect of the IVC, across the foramen ovale (FO) and into the left atrium (LA). In the LA, the oxygen saturation of fetal blood is 65%.
This better oxygenated blood enters the left ventricle (LV) and is ejected into the ascending aorta. The majority of the LV blood is delivered to the brain and coronary circulation thus ensuring that blood with the highest possible oxygen concentration is delivered to these vital structures.
Oxygen delivery is dependent on haemoglobin concentration, cardiac output and oxygen saturation.
The cardiac output of the fetus is regarded as the total output of both ventricles - the combined ventricular output (CVO). About 45% of the CVO is directed to the placental circulation with only 8% of CVO entering the pulmonary circulation. The presence of fetal haemoglobin and a high CVO will help to maintain oxygen delivery despite low PaO2.
With the high pulmonary vascular resistance and the presence of the ductus arteriosus most of the right ventricular output passes into the arch of the aorta just distal to the origin of the arteries to the head and upper limbs.
Neonates
how do they produce heat
how much heat loss uncovered head
where are temp reeceptors located
what speed change response
where responds to heat
where respond to cold
Neonates have a large surface area in relation to body mass, low heat production and low tissue insulation all of which predispose to rapid heat loss.
They are unable to shiver and produce heat by non-shivering thermogenesis, which involves the oxidation of triglycerides located in brown fat. Brown fat is located at the base of the neck, axillae, inter scapular region and in the mediastinum.
An uncovered head can account for 60% of total heat loss.
Temperature receptors are located in the skin, CNS and gastrointestinal system and they are more sensitive to rapid changes than to gradual ones.
In both neonates and adults the anterior hypothalamus responds to heat and the posterior hypothalamus responds to cold.
HbF
differs from adults how
ODC versus adult
why
When is it replaced to adult
how acute
When is screen
When does EPO prod start
Fetal haemoglobin (HbF) differs from adult haemoglobin by gamma chains replacing the beta chains.
The oxygen dissociation curve for HbF is to the left of adult haemoglobin (not right), facilitating the transfer of oxygen from the maternal circulation to the fetus.
HbF is gradually replaced by adult haemoglobin during the first 6 months of life. Thus sickle cell disease does not present during the neonatal period and screening only needs to be performed after the age of 3 months (when the proportion of adult haemoglobin has started to increase).
Erythropoietin production starts in utero, and then production falls after birth with an increase seen at about 3 months resulting in a reticulocytosis.
Erythrocyte survival is shorter in neonates (not longer) than in adults.
Physiology of PDA
why have it
when does it close
Why would it be kept open?
how is it closed
how is it kept open
what causes a higher incidence
The physiological function of the ductus arteriosus in the fetus is to divert blood away from the lungs to the placenta.
Constriction and functional closure occurs in the first 24 hours of life in response to increased environmental oxygen.
In order to maintain life with some cardiac malformations, for example, pulmonary atresia, hypoplastic left ventricle and interrupted aortic arch, these patients require patency of the duct after birth.
Indomethacin causes duct closure (not patency) through an anti-prostaglandin effect.
An infusion of alprostadil is used to maintain duct patency.
Incidence of PDA is greater in preterm infants and birth at high altitude is associated with a greater risk.
How maintain a PDA
R-L shunt
allows blood bypass non vented lungs
patency maint low po2
pge2
how close pda
nsaid -{ prostaglandin
Indomethacin - nsaid closes
