Sickle Cell Flashcards
Sickle Cell Crises
Sickle cell anaemia is characterised by periods of good health with intervening crises
Four main types of crises are recognised: thrombotic, 'painful crises' sequestration aplastic haemolytic
Thrombotic Crises
Thrombotic crises
also known as painful crises or vaso-occlusive crises
precipitated by infection, dehydration, deoxygenation
infarcts occur in various organs including the bones (e.g. avascular necrosis of hip, hand-foot syndrome in children, lungs, spleen and brain
Sequestration Crises
Sequestration Crises
sickling within organs such as the spleen or lungs causes pooling of blood with worsening of the anaemia
acute chest syndrome: dyspnoea, chest pain, pulmonary infiltrates, low pO2 - the most common cause of death after childhood
Aplastic Crises
Aplastic crises
caused by infection with parvovirus
sudden fall in haemoglobin
Haemolytic Crises
Haemolytic crises
rare
fall in haemoglobin due an increased rate of haemolysis
Sickle Cell - Priapism is a Cx: Example Question
A 22-year-old man with sickle cell disease is seen in the Emergency Department. He has had worsening pain in his arms and legs for the last 2 days and 5 hours ago developed a painful sustained erection.
He has felt otherwise well recently and has no other past medical history. He is on regular paracetamol, ibuprofen, folate and penicillin. He does not receive regular transfusions and has been admitted with a crisis only once before. He has never had an episode of painful sustained erection.
On examination he has a heart rate of 110 beats per minute and a blood pressure of 132/95 mmHg. His oxygen saturations are 96% on room air and he is afebrile. His chest is clear and abdomen is soft. He has no swelling or erythema of his limbs, though they are generally tender. He continues to have an erection, though there is no sign of ischaemia.
His chest x-ray shows clear lung fields.
His blood tests are as follows:
Hb 78 g/l Na+ 141 mmol/l Platelets 331 * 109/l K+ 3.7 mmol/l WBC 9 * 109/l Urea 5 mmol/l Neuts 7 * 109/l Creatinine 86 µmol/l Lymphs 1.6 * 109/l CRP 14 mg/l
He is treated with intravenous fluids and generous analgesia with diamorphine. His limb pain is improved but he continues to have a painful erection.
What is the next most appropriate step?
Adrenalin Diethylstilbestrol Exchange transfusion > Review by urologist Sildenafil
This gentleman has priapism, a sustained painful erection lasting 4 hours. If left untreated it can result in impotence. Current guidelines recommend initial conservative management with fluids and analgesia. Although any interventions beyond this have variable results, evidence supports prompt urology review to determine the need for surgical management including drainage. There is insufficient evidence to recommend routine exchange transfusions. Sildenafil, diethylstilbestrol and adrenalin may be used in consultation with urology but evidence of benefit is variable.
Aplastic Crisis - Example Question
A 33-year-old patient presents to the emergency department feeling very lethargic and tired over the last week. He has been increasingly short of breath on exertion and his exercise tolerance has fallen to a few hundred yards before he is out of breath. He is a known sickle cell disease patient who is managed by the Haematology team in your hospital. On examination he is afebrile and heart rate and blood pressure are within normal limits. His respiratory rate is 16/min and his oxygen saturation is 98% on air. He does become noticeably short of breath on minimal movement.
His blood tests show:
Hb 65 g/l Platelets 46 * 109/l WBC 2.5 * 109/l Neuts 1.2 * 109/l Haptoglobins 1.9 g/L (0.3-2.0) Reticulocytes 8.9 x10^9/L (25-80)
Na+ 136 mmol/l K+ 3.9 mmol/l Urea 7.4 mmol/l Creatinine 78 µmol/l CRP <3 mg/L(<10) LDH 200 IU/L (200-500)
Bilirubin 4 µmol/l
ALP 89 u/l
ALT 34 u/l
Albumin 39 g/l
His chest x-ray is normal.
On further questioning, he tells you that his 5-year-old daughter was unwell 3 weeks ago. He took her to see the GP and was told it was likely to be a viral illness. What is the most likely cause for his blood results as shown?
> Parvovirus B19 Acute chest crisis Splenic sequestration HIV Legionella pneumoniae
This gentleman has had an aplastic sickle cell crisis as a result of parvovirus infection. He has symptomatic anaemia. There is nothing to suggest splenic sequestration and he is too well for an acute chest syndrome. The normal chest x-ray is not in keeping with a pneumonia. HIV is a possibility but less likely given the clinical picture.
Acute Chest Syndrome (Sequestration crisis): Example Question
A 23 year old male of Nigerian descent is referred from the ED with acute shortness of breath associated with fever and dry cough. His shortness of breath has limited him to an exercise tolerance of around 10 yards. He also complains of excruciating right sided chest pain. He is known to have sickle cell anaemia and has had no admissions to the hospital in the last 3 years.
Observations heart rate 94bpm regular blood pressure 112/74 mmHg temperature 38.3 respiratory rate 22 urine output under 30ml/hr oxygen saturations 93% on room air
Examination
respiratory system shallow breathing, bronchial breath sounds with crepitations to right base
Blood results:
Hb 7.7 g/dl
Platelets 200 * 109/l
WBC 13.2 * 109/l
Bilirubin 36 µmol/l
Urea 8.2 mmol/l
Creatinine 146 µmol/l
What is the most important initial steps in management?
> Oxygen, IV fluids, antibiotics and analgesia 2 unit blood transfusion and analgesia Oxygen and analgesia only Antibiotics and IV fluid only Plasmapheresis and analgesia
It is important to recognise and treat sickle cell crises (as detailed above) as a matter of urgency. This condition can be quickly fatal. This patient should be treated as per sepsis guidelines. It is crucial to adequately control the pain in this patient cohort as not being able to inhale deeply due to pain will only serve to worsen the lung damage. Early assessment for the involvement of the critical care team is required as acute respiratory distress syndrome is a real possibility. Oxygen saturation levels should be maintained above 95% in a patient where a normal steady state level is not known. Management of this and the haemaglobin level should be specific for the patient and compared to past levels. The question states that the patient has had no admissions to the hospital in the last 3 years and as such the aim should be to keep oxygen saturations above 95%.
Acute Stroke in a Sickle Cell Patient: Example Question
A 35-year-old patient with known sickle cell disease presents to the emergency department with new onset of left arm and facial weakness. The symptoms began earlier in the day. He is normally very careful with his sickle disease and ensures he is well hydrated and avoids the cold. His wife admits that over the last few days he has been suffering from nausea and vomiting and diarrhoea after he had a takeaway meal 3 days ago, On examination he his observations are within normal parameters. He has slurred speech and an obvious left facial droop with forehead sparing. He has power of 0/5 in his left arm but is otherwise neurologically intact.
His blood test show:
Hb 100 g/l
Platelets 330 * 109/l
WBC 8.9 * 109/l
INR 1.0
Na+ 138 mmol/l K+ 3.5 mmol/l Urea 9.9 mmol/l Creatinine 135 µmol/l CRP 19 mg/L(<10)
Bilirubin 12 µmol/l
ALP 89 u/l
ALT 39 u/l
Albumin 39 g/l
He is seen by the stroke team who arrange an urgent CT head which is reported as normal. What is the appropriate treatment for this gentleman?
Thrombolysis Aspirin Plasmapheresis Methylprednisolone > Exchange transfusion
This gentleman has a cerebral vaso-occlusive episode as a result of his sickle cell disease. The treatment of choice in these situations is urgent and aggressive exchange transfusion followed by transfusions to maintain HbS <30%. Thrombolysis and aspirin are not in the management guidelines for acute stroke in this situation.
Acute Stroke in Sickle Cell Disease - Mx
Urgent and aggressive exchange transfusion followed by transfusions to maintain HbS <30%. Thrombolysis and aspirin are not in the management guidelines for acute stroke in this situation.
Sickle Cell Crises - Mx
Sickle-cell crises: management
General management
analgesia e.g. opiates
rehydrate
oxygen
consider antibiotics if evidence of infection
blood transfusion
exchange transfusion: e.g. if neurological complications
Acute Stroke in Sickle Cell - Example Question
A 28-year-old Afro-Caribbean male presents with a two-hour history of sudden onset left sided weakness. He denies any sensory involvement, dysarthria or dysphasia. He has a known history of sickle cell disease, with two previous episodes of transient ischaemic attacks and an episode of acute chest syndrome attack 10 days ago. On examination, he displays power of 1/5 in his left arm, 2/5 in his left leg, 5/5 in his right side. He reports no sensory disturbances, plantar responses are downgoing bilaterally, he is unable to perform finger-nose testing. He denies any illicit drug use, is a non-smoker and does not drink alcohol. He has no other past medical history. A hyperacute CT head demonstrates an area of acute ischaemia in the right internal capsule region. What is the most appropriate immediate treatment?
Intravenous thrombolysis Aspirin 300mg Intravenous thrombolysis and mechanical thrombectomy > Exchange transfusion Clopidogrel 300mg
This patient has presented with an acute vaso-occlusive crisis on a background of known sickle cell disease. He is at high risk of an infarctive stroke given the background of previous TIAs (increased relative risk by 56 times) and a recent chest crisis within the past 2 weeks (increased relative risk by 7 times). The other risk factors include a high systolic pressure (RR 1.3 increase per 10mmHg) and a low steady state haemoglobin (RR 1.9 per 1g/dL decrease)1. The management of an acute sickle infarct is different to that of thromboembolic stroke or atheromatous disease. The immediate aim is to reduce the proportion of HbS, either with immediate transfusion or optimally, with exchange transfusion. The latter reduces the concentration of HbS faster with a lower risk of transfusional volume overload, possibly resulting in increased blood viscosity and consequent pulmonary oedema.
Acute Chest Syndrome
Defined as ‘acute illness characterised by fever and/or respiratory Sx accompanied by new pulmonary infiltrate on CXR’
Fundamentals of Initial Mx:
- Oxygen therapy to maintain sats >95%
- IV Fluids to ensure Euvolaemia
- Adequate pain relief
- Incentive spirometry in all patients presenting with rib or chest pain
- Abx cover for atypical organisms
- Early consultation with the critical care team and haematology
NB On presentation patients should be FULLY CROSS MATCHED and Hx of Red Cell antibodies sought
A senior haematologist will decide whether a simple or exchange transfusion is necessary - guidelines suggest Hb target of 100-110g/L in either instance
Bronchodilators only indicated if asthma co-exists with acute chest or if evidence of acute bronchospasm on auscultation
Sickle Cell and Osteomyelitis - Example Question
A 6 year-old boy from Sierra Leone presents with a 1 week history of painful left arm. He is homozygous for sickle cell disease. On examination the child is pyrexial at 40.2ºC and there is bony tenderness over the left humeral shaft. Investigations are:
Hb 7.1 g/dL
Blood culture Gram negative rods
X-ray left humerus: Osteomyelitis - destruction of bony cortex with periosteal reaction.
What is the most likely responsible pathogen?
Escherichia coli > Non-typhi Salmonella Pseudomonas aeruginosa Staphylococcus Aureus Parvovirus B19
Blood and bone infections caused by non-typhi salmonella (NTS) are typically associated with malaria and homozygous sickle cell disease, especially in children. The reason for this perceived susceptibility is not fully understood - but it may be in part due to the haemolysis and subsequent iron availability to the bacteria, which is ‘siderophilic’ in nature.
E.coli and P. aeruginosa are not typically linked to sickle cell disease and Staphylococcus aureus is a gram positive coccus.
The haemoglobin level is normal for a child homozygous for sickle cell disease. Therefore ‘aplastic anaemia’ should not be considered and parvovirus can be ruled out. Parvovirus does not cause osteomyeltitis.
