Special Populations Flashcards
Elderly Physiology
Physiological changes of ageing
Body water
•total body water decreases 15%
•ECF decreases 40%
•plasma water 8%
Body composition
•decreased muscle mass
•increased body fat
•decreased plasma proteins
Cardiovascular •decreased cardiac index •increased systemic vascular resistance -both 1% / year •decreased ability to increase heart rate to stress
Pulmonary •decreased compliance •greater dependence on diaphragmatic breathing •atrophy of -alveoli -cilia
Renal
•loss of renal mass after 50 years of age
•GFR decreases 50% from age 40 to 80
GIT effects •decreases hepatic first pass effect •decreased p450 activity •altered gut surface area •decreased GIT motility •decreased gastric acid secretion
Metabolic
•reduction in mixed function oxidase activity
-glucuronidation unchanged
Musculoskeletal
•decreased elasticity
-ligament injuries rare
-less contraction of bleeding vessels
•loss of bone density
-fractures more common
Immune
•decreased cell mediated and humoral immunity
•decreased peritoneal signs
Other
•increased drug receptor affinity
•increased sensitivity to CNS and CVasc drugs
Frequent ED attenders - Factors associated
Factors associated
- male gender
- older age
- attendance outside daytime hours
- substance abuse
- psychosocial problems
- intellectual disability
- somatic delusions
- chronic medical problems
- used multiple heath services regularly
Factors associated with DNW
Factors associated with DNW
- prolonged waiting time – most common reason
- lower socioeconomic background
- lack of private health insurance
- young adults
- parents with young children
- less urgent triage categories (ATS 4 or 5)
- ED overcrowding
- ED attendance after hours
Competence to give conset
Patient features of competence to give consent
•age - no absolute rules
- 18 years or older usually considered competent
- 14 - 17 years - variable
- < 14 years - usually considered to be non competent
•have the cognitive capacity to understand
- the medical condition
- the options for treatment
- what is recommended
- the potential adverse outcomes
- the likelihood of these
- usually have a MMSE score of > 20
- patients should be able to
- accepted information as reality
- retain information provided
- paraphrase information
- explain the possible consequences
- indicate the major factors in their decisions and the importance assigned to them
Consent for Minors
Minors
- parents or legal guardians have power of consent
- if age < 14 years - patient is usually considered unable to legally give consent
- if parent not available to consent and unable to contact by telephone - treat by implied consent
•if age 14 or older, living independently (may be difficult to define) and considered capable of making an informed decision
-medical information cannot be supplied to others (i.e. parents) without the patient’s consent
•treatment of life saving nature may be given despite parental objections
-guardianship agencies will need to be involved
Coroner - Reportable deaths
•a death in custody
- police
- correctional services
- mental health detention
- a death by unusual, unexpected, unnatural, violent or unknown cause
- a death during, as a result of, or within 24 hours of a surgical, invasive or diagnostic procedure including the administration of an anaesthetic for the carrying out of the procedure
- a death within 24 hours of being discharged from a hospital or having sought emergency treatment at a hospital
- a death of a person under a guardianship or child protection order
- a death on an aircraft or vessel with a place within the jurisdiction as its place of disembarkation
- a patient death in an approved treatment centre under the Mental Health Act
- a death in a hospital or treatment facility for the treatment for a drug addiction
- a patient death in certain residential care facilities
- if no certificate as to the cause of death has been issued to the Registrar of Births, Deaths and Marriages
- death of a person with unknown identity
Discharge against medical advice - questions to be answered
Questions to be answered
- Is there a duty of care?
- Why do they want to leave?
- Can someone else legally determine consent?
- What is the risk to the patient of DAMA?
- What is the risk to the patient of restraint?
- Is the patient capable of refusing consent?
Physiological Changes in Pregnancy
Cardiovascular
Heart
•displaced upward and to the left with rotation on its long axis
•apex beat moved laterally
-ECG may show left axis deviation, flat T-waves in III
•heart size increases by 10%
•cardiac output increased 40%
-maximum from 20-40 weeks
•heart rate increases 15-20 /min. by term
•blood pressure falls 10-15 mmHg in 2nd trimester
•SVR reduced by 20%
Auscultation
•first heart sound may be split
•third heart sound may be louder
•90% of pregnant women have a late systolic or ejection murmur
-disappears soon after delivery
-a soft diastolic murmur may also be present
•continuous murmurs or bruits can be heard at the left sternal edge, due to the internal thoracic (mammary) artery
Pericardial effusion
•asymptomatic pericardial effusion present in healthy pregnancy in
-15% during the first trimester
-20% during the second trimester
-45% during the third trimester
•effusions are usually small but can be moderate or large
•effusions resolve by 6 weeks post partum
•pericardial effusion also seen in 20% of women following stimulation for IVF or embryo transfer
Blood volume •increases by 50% by 28/40 -begins in the first trimester -increases rapidly in the second trimester -plateaus at about the 30th week
Other
•supine hypotensive syndrome from IVC compression
•SVT more common
•uterine blood flow increases 100 fold
-500 mL/min at term
•increased skin blood flow
•BNP increases to > 100pg/L in 5% post partum
-may persist for 6-12 weeks
-elevations can occur in pregnancy related hypertensive illnesses
•CKMB increased in 35% post partum
Haematological
Red cells
•red cell mass increases 33%
•dilutional anaemia, Hb < 120g/L
-haematocrit falls until the end of the 2nd trimester
White cells
•WCC
-up to 16,000 may be normal in third trimester
-up to 30,000/µL in normal patients during labour
•rise primarily involves the polymorphonuclear forms
•decreased polymorphonuclear leukocyte adherence in the third trimester
•basophil numbers decrease slightly
•mean ESR at term is 78 mm/min
Platelets
•See also Pregnancy related
•normally progressively decrease during pregnancy
Coagulation factors
•marked increases in
-fibrinogen
-factor VIII
-factors VII, IX, X, and XII also increase to a lesser extent
•fibrinogen
-starts to increase during the third month of pregnancy
-rises until late pregnancy
•prothrombin not significantly affected
•mild increases in factor V
•factor XI decreases slightly toward the end of pregnancy
•factor XIII reduced by up to 50% at term
•fibrinolytic activity is reduced
-plasminogen levels increase
-increased D dimer
D dimer •D-dimer levels elevated in -15–50% in first trimester -67–78% in second trimester -> 95% in third trimester •markedly elevated during labour •decrease rapidly in first 3 days post-partum •normalisation usually occurs by 4 weeks
Respiratory
- maternal O2 consumption increased by 20-40%
- increased vascular lung markings on CXR
Thoracic changes
•diaphragm elevated up to 4 cm
•lower thoracic diameter increases by 2 cm
•thoracic circumference increases by up to 6 cm
•respiration becomes more diaphragmatic
Lung volumes
•dead space increases
-relaxation of the musculature of conducting airways
•total lung capacity reduced by 5% due to elevation of the diaphragm
•FRC, RV and ERV decrease by 20%
•tidal volume increases by 40%
•minute volume increases by 25%
-produces a compensated respiratory alkalosis
•vital capacity and respiratory rate remain unchanged
•alveolar ventilation increased by 65%
•normal pCO2 at term is 25-33mmHg
Gastrointestinal
Motility
•motility decreases due to
-increased circulating progesterone and oestrogen
-nitric oxide release from nonadrenergic noncholinergic nerves
•gastro-oesophageal sphincter relaxes
Mechanical
•cephalad displacement of intra-abdominal organs
•stretching and desensitisation of peritoneum
-fewer peritoneal signs in the presence of intra-abdominal irritation
Liver •no morphologic changes during normal pregnancy •ALP activity can double, due to placental isoenzyme •decrease in plasma albumin by 5 g/L •slight decrease in plasma globulins -decrease in albumin:globulin ratio •mild decrease in -AST -ALT -GGT
Gall bladder
•emptying slowed
•bile stasis may lead to gallstone formation
•chemical composition of bile is not changed
Other
•salivation may seem to increase due to swallowing difficulty associated with nausea
•gums may become hypertrophic and hyperaemic
-may bleed easily
-due to increased systemic oestrogen
•more water than normal is reabsorbed, leading to constipation
Metabolic
•increased metabolic rate
•electrolyte changes in late pregnancy
-Na+ 3-5 mmol/L lower
-K+ 0.5 mmol/L lower
-calcium and magnesium 0.2 mmol/L lower
-normal HCO3 range
•plasma cholinesterase activity decreased
•increase in plasma cholesterol of up to 50% in 2nd half of pregnancy
•plasma triglyceride concentrations may triple
•triglycerides, cholesterol, and lipoproteins decrease soon after delivery
•LDL:HDL ratio increases
•insulin resistance
•10% of women have anti-thyroid peroxidase antibodies at 16 weeks gestation
-50% develop post-partum thyroid dysfunction - usually transient hypothyroidism
Renal
GFR
•increases by 50%
-starts early in pregnancy
•normal values return by 20 weeks post-partum
Creatinine clearance
•peaks at 50% above non-pregnant levels at 32 weeks gestation
•decreases as term approaches
•due to the increase in GFR
•urea similarly affected
Glycosuria
•not necessarily abnormal during pregnancy
-glucose is excreted in the urine during pregnancy in > 50%
•due to increased GFR with impaired tubular resorption capacity
Other
•normal pregnant women have increased urinary losses of
-amino acids
-water-soluble vitamins
Kidneys
•increase in
-length by 1-1.5 cm
-volume by 30%
•renal pelvis dilates up to 60 mL
-normally 10 mL in non-pregnant women
•ureter dilates above the pelvic brim
-dextrorotation of the uterus during pregnancy may cause right ureter to be more dilated than the left
-right hydroureter present in 85% of women late in pregnancy
•urinary stasis
-up to 200 mL of residual urine present in the dilated collecting system
Bladder
•is an abdominal organ
•flattened in the AP diameter
•capacity increases to 1,500 mL
PE investigations in pregnancy
D-dimer
- concentration rises gradually during pregnancy
- specificity of D-dimer testing in pregnancy and the postpartum period is lower than normal
- pregnancy adjusted d dimer levels have been proposed, however none have been prospectively validated
- negative predictive value is still high so a negative D-dimer usually does not require further investigation
Imaging
•concern about exposure to radiation should not outweigh use of CTPA or VQ scan when indicated
-mortality associated with untreated PE > risk to the fetus of exposure to diagnostic imaging
•fetal radiation dose from a
-CXR at any gestational age is negligible (<0.1 mGy)
-CTPA (0.1 mGy) is less than the estimated fetal radiation exposure from VQ scanning (0.5 mGy)
-these exposures are well below the levels associated with teratogenesis
•where possible, use modified imaging protocols to reduce radiation exposure
Ultrasound
•despite low sensitivity may be reasonable first line test in suspected PE as it is fairly specific
•does not detect pelvic DVT
VQ scan
•investigation of choice for evaluation of PE in pregnant patients
•less maternal radation (especially to the maternal breasts), greater fetal radiation than CTPA
•radionuclide has minimal risk and is safe in pregnancy
•diagnostic quality VQ obtained in 97% of pregnant patients
-when CXR normal and no history of asthma or chronic lung disease
•73%–92% of V/Q scans in pregnant patients are normal
•radiation dose reduction possible
-ventilation scan omitted when perfusion normal
-decrease dose of perfusion component by 50%
•minimise radiation to the pelvis by
-high urine flow
-frequent voiding after injection of radionuclide
CTPA
•commonly used in pregnant patients with suspected PE
•less fetal radiation, more maternal radiation than VQ
•dose reduction methods possible
-alter CT acquisition parameters (maintaining diagnostic quality)
-use of bismuth breast shields to decrease maternal breast dose
-lead shielding to minimise radiation exposure to the fetus
•physiological changes of pregnancy may increase non diagnostic rate
•theoretical risk of iodinated contrast material to fetus
MRI
- no radiation
- gadolinium based contrast agents not proven to be safe in pregnancy
- role in pregnancy need clarification
Trauma in Pregnancy - Specific Assessment and Management concerns
Important points
- evaluation of haemodynamic state may be difficult
- borderline tachycardia difficult to evaluate
- signs of blood loss blunted due to 50% increase in plasma volume and 20-30% RBC volume by 3rd trimester
•increased risk of pulmonary aspiration
-due to reduced competence of gastro-oesophageal sphincter
•increased sensitivity to hypoxia
- FRC decreased by 20%
- O2 consumption increased by 20% in second trimester
•premature labour may go unnoticed especially if intubated, paralysed or mentally obtunded
•clinical features of peritoneal irritation often reduced in later pregnancy
-uterine displacement of intestines and stretching of peritoneum
•fetal compromise may be occurring even in the asymptomatic patient
Trauma - Problems unique to pregnant patient
- fetal distress
- placental abruption
- inelastic placenta shears away from wall of elastic uterus as it is deformed by trauma
- occurs in 2-4% of minor trauma, 50% of major trauma
- may have little external abdominal wall trauma
- maternal mortality < 1%, fetal mortality 20 -35%
- may be difficult to detect on US
- is a clinical diagnosis
- amniotic fluid embolism
- uterine rupture
- laceration of placenta or cord
- premature rupture of the membranes
- premature labour
- fetomaternal haemorrhage
- direct fetal injury (uncommon)
Paediatric Airway - specific issues
General Problems
•exposure -large surface area / body weight ratio leads to loss of heat 50 -70 times the rate of an adult •hypoglycaemia & hypocalcaemia -neonates are especially at risk •obtaining IV access
Airway and ventilation
•high metabolic rate + low O2 storage capacity means they can go blue very fast!!!
-limit intubation attempts to 30 seconds duration
•large floppy head that is difficult to control
-often helps to have a second person to assist
Anatomy of the larynx
•high -C 3 - 4 -C5-6 in an adult •anterior position and inclination -pressure backwards on the larynx rather than the cricoid will bring the cords into view •large tongue and small mouth
Epiglottis
- U shaped compared with the crescent shape of an adult
- floppy
- straight blade passes dorsal to it
- may be pushed inferiorly by large oral airway
Airway diameter
•cricoid ring is the narrowest part of the airway
-vocal cords in an adult
•a tube that fits snugly through the cords will be too tight at the level of the cricoid
•tube size must be small enough to allow an audible air leak around the tube and through the cords
-if there is no leak, the tube is too large and problems of airway oedema may occur
•as tube size decreases, resistance increases by the fourth power of the radius
•nasal tube
-pick the size to pass through the cricoid
-thus same size as an oral tube
Respiratory function
- horizontal ribs, thus loss of the bucket handle movement and reliance on the diaphragm for respiration
- diaphragm more limited in downward excursion
- stomach distension causes splinting of the diaphragm
-passage of a NGT or orogastric tube can significantly improve ventilatory function
•AP expansion is significantly decreased in infants, thus added reliance on diaphragmatic movement
•short trachea
-tube easily displaced
•bronchial angles in neonates
-studies in children have shown that the tube is equally likely to go down the right or the left side
•small chest size
- breath sounds transmit well (including from oesophagus)
- auscultation may be misleading following intubation
Paediatric Trauma
Patterns of injury
•different to adults due to increased elasticity of tissues and large head mass
- head injury more common
- rib fractures less common
- pulmonary contusion more common
Paediatric cervical spine injury •serious cervical spine injury rare -only about 1/3 require any intervention •but more likely to be high cervical when present -underdeveloped neck muscles -large head
•MRI (or CT if MRI not available or CT performed for another reason) cervical spine in children < 10 years of age uncommonly required unless exceptional circumstances
- GCS < 9
- other regions being scanned
- avoided whenever possible due to risk of radiation exposure to thyroid gland
Differences in airway
Differences in normal vital signs
Metabolic
•attention to thermal control important
•higher risk of developing hypothermia than adults
•correct glycaemic control more important than in adults
Blood volume
•greater than that of adults on a mL/weight basis
Bone
•epiphyseal injuries need to be considered
•the large occiput in infants causes flexion of the Cx spine
•significant differences in radiological interpretation of the Cx spine
Acute gastric distension
- common in paediatric resuscitation
- may compromise respiratory function
- requires NGT /OGT insertion and decompression
Abdominal injuries
•bladder is intra-abdominal in children, so more easily injured
•FAST accuracy appears to be lower in children
•solid organ injury is more commonly managed non operatively in children
•duodenal injuries more common in children
•seat belt sign
-bruising of the abdominal +/- chest wall due to forceful restraint by a seatbelt
-approximately 15% of children have intra-abdominal injuries and 50% of these require an intervention
•no indication for CT chest in a child with a normal CXR
