FCA 2020 Flashcards
Question 1 A 20-year-old healthy male is involved in a motor vehicle collision. He sustains facial injuries including maxillary fractures. With regard to intubation choices, fill in the table below. [10]
Question 2 a) List 5 personal attributes required of a medical professional and specialist anaesthesiologist in the clinical context.
As senior consultant, you welcome a new colleague into your department. He asks your advice in terms of self-organisation and self-management. How would you advise him about the requirements for practising full time in a public institution?
a) List the ideal anaesthetic conditions for corneal transplant surgery.
What are your concerns with regards to the use of suxamethonium in corneal transplant surgery?
Name two regional anaesthetic blocks that may be used for corneal transplant surgery. (1)
Which component of regional anaesthetic blocks for ocular surgery may affect intraocular pressure?
What are the limitations of using regional anaesthesia for corneal transplant surgery? (2)
Question 4 a) Briefly outline the preoperative and intraoperative factors and pathophysiological processes that may contribute to the acute coagulopathy that develops during major vascular surgery.
List three point of care tests that may help to elucidate the cause of the acute coagulopathy during major vascular surgery.
Question 5 An unbooked 24-year-old patient presents to your tertiary hospital in active labour and foetal distress. She has differential cyanosis with clubbing of the toes. The diagnosis of a longstanding Patent Ductus Arteriosus (PDA) is made clinically by the cardiologist. a) Name 4 cardiovascular changes during normal pregnancy at term relevant to this patient.
Increased blood 35% and plasma volume 55%
Increase cardiac output 40%
Reduction in systemic vascular resistance 15% pulmonary vascular resistance 30%
What monitoring is needed above the standard monitoring?
A-line
CVP
Briefly explain the main reasoning behind your chosen anaesthesia technique.
Patient WHO class one with no detectable increased risk of maternal mortality and no/mild morbidity.
Spinal anesthesia
• Reduce SVR limit left to right shunt
• Thus reduce increases in pulmonary blood flow
• Avoids airway manipulation in high risk for aspiration and possibly difficult airway patient
• Avoids blood pressure swings with sympathetic activation during laryngoscopy and extubation, hypotension post induction.
• Better pain score
• Lower risk of DVT
• patient satisfaction
Question 6
A term infant born 6 hours ago presents with respiratory distress and a saturation of 82% on nasal prongs. He is diagnosed with congenital diaphragmatic hernia. a) When would be the ideal time to correct the hernia surgically?
Inutero for those with LHR low and predicted to have poor outcomes
○ Recommendations from the CDH EURO Consortium state that the following physiological parameters should be met before surgery:
(i) mean arterial pressure normal for gestation,
(ii) preductal oxygen saturation consistently 85-95% on FiO2 <0.5,
(iii) lactate below 3 mmol litre1, and
(iv) urine output more than 1 ml kg/hr.
Question 6 A term infant born 6 hours ago presents with respiratory distress and a saturation of 82% on nasal prongs. He is diagnosed with congenital diaphragmatic hernia. b) List all the factors likely to contribute to the hypoxia
• Affected lung is intrinsically abnormal
• Under-developed airways
• Abnormal differentiation of type II pneumocytes
• ↓ number of pulmonary arteries per unit lung volume
• Intrapulmonary arteries become excessively muscularized with thickened adventitia & media
& muscularization extends peripherally
• Pulmonary vessels display exaggerated response to vasoactive subs
Question 6 A term infant born 6 hours ago presents with respiratory distress and a saturation of 82% on nasal prongs. He is diagnosed with congenital diaphragmatic hernia.
c) Briefly discuss how the anaesthetist should avoid worsening of the hypoxia in the perioperative period.
- Optimisation of ventilation
- Maintain cardiac output, give 10ml/kg bolus x2 with ionotropic support to maintain MAP
- Prevent pulmonary hypertension exacerbation by warmining, prevent excessive hypercarbia, give adequate oxygen, maintain PH >7,25
- Pulmonary vasodilators
- Ventilation aims
Preductal SpO2 between 85% to 95%
○ Postductal SpO2 > 70%
PIP < 25 cmH2O with a ○ PEEP set between 3 to 5 cmH2O
FiO2 < 50%, titrated to preductal SpO2 goals
Respiratory rate between 40 to 60 breaths per minute
PaCO2 between 50 to 70 mm Hg
the pH of 7.25 and above
ECMO INDICATIONS
○ Preductal SpO2 < 85% or postductal SpO2 < 70%
PaO2 < 40 mm Hg
Mixed venous saturation < 60%
Oxygenation index > 40 for at least 3 hours
Mixed acidosis pH < 7.2 with hemodynamic instability
Requiring PIP > 28 cmH2O or MAwP > 15 cmH2O to maintain oxygenation
Lactate > 5 mmol/L with a pH < 7.2
Hypotension refractory to fluids and pressors
Severe air leak and requiring high ventilatory settings
Question 7 A 38-year-old woman with a diagnosis of acute appendicitis undergoes an open appendicectomy under general anaesthesia. She is known with idiopathic pulmonary arterial hypertension of 10 years duration managed on home oxygen therapy and sildenafil 50mg 6 hourly. A recent work-up for lung transplantation measured her mean pulmonary arterial pressure at 57mmHg. Intra-operatively her oxygen saturations (SaO2) range between 89% and 91% on an FiO2 of 0.60. Towards the end of the procedure her SaO2 rapidly decreases to 68% despite an increase in FiO2 to 1.0. Her ventilation pressures and end-tidal CO2 remain within normal limits. a) What is the likely aetiology of this patient’s clinical deterioration?
b) Name ONE monitoring modality, other than basic and arterial blood pressure monitors, that would help in the diagnosis and management of this episode. (PULMONARY HPT) (1)
c) List the drugs you could use to treat this evolving clinical scenario (assume all are readily available). Briefly describe their mechanisms of action (pulmonary hypertension exacerbation with hypoxia intraoperative)
Question 8 A 5-year-old boy with a history of unrepaired tetralogy of Fallot (TOF) is seen in the emergency unit complaining of headache after a seizure at home. High definition computed tomography without contrast reveals a lesion suggestive of an abscess in the right temporo-parietal region with significant midline shift. On examination he is awake and oriented with no focal deficits. He has no papilloedema. He is pyrexial (38.4°C), clubbed and centrally cyanosed. He weighs 12kg and has an Hb of 16.2g/dl. The patient is booked for an urgent craniotomy for abscess drainage. a) Briefly describe your perioperative anaesthetic management of this patient?
Question 9
During a pre-operative visit for a patient presenting for a laparotomy, the patient tells you he was diagnosed with porphyria at a young age. He mentions that tests were done and he was told he has
an acute type of porphyria.
a) The acute types of porphyria can complicate into acute neurovisceral crisis.
i) List 4 triggers for acute neurovisceral crisis in the perioperative period. (2)
TRIGGERS:
- fasting
- dehydration
- infection
- drugs
- endogenous hormones
- stress (physical/emotional)
- smoking
- alcohol
ii) List 2 cardiovascular symptoms that manifests during an acute crisis porphyria. (1)
Tachycardia
Tachyarrhythmia
Hypertension
List the 3 mechanisms of drug porphyrinogenicity.
c) How will you manage an acute porphyria crisis? (4)
Supportive Measures:
1. Immediate cessation of any medication that is not known to be safe in porphyria
2. Pain management: patients require frequent, high doses of opiate analgesia as pain is severe and recurs after a short interval. Opiate dependence in acute porphyria is rare as the need for high, frequent doses of opiates is genuinely in response to excruciating pain.
Recommended analgesic agents:
- Pethidine: patients may require 50-100mg hourly
- Morphine
Drugs to avoid:
- Antispasmodics (e.g. Hyoscine butylbromide)
- These may precipitate an acute attack.
3. Vomiting and Nausea: Recommended antiemetics:
- Metoclopramide, prochlorperazine
4. Hypertension and Tachycardia: hypertension is usually mild and subsides without specific treatment. In cases of severe hypertension Beta-adrenergic and Alpha-adrenergic blockers can be used. Beta-blockers are, in themselves, anti-porphyrinogenic and are
therefore beneficial. Magnesium sulphate may also be added in the rare event of severe hypertension not responding to Beta and Alpha-adrenergic blockers.
5. Fluid therapy and Carbohydrate intake(15)
.
Patients with acute porphyria are often dehydrated due to vomiting and poor oral intake.
Electrolyte imbalance is also common. These include: hyponatremia, hypomagnesemia
and hypokalaemia. Decreased caloric intake may precipitate or worsen an acute porphyric
crisis. Therefore, an adequate fluid and carbohydrate intake is important.
Recommended Fluid Therapy:
- 5% Dextrose Saline (2 litres will provide 100g of glucose a day)
- As soon as patients are able to tolerate oral intake the should be transferred to a diet in
which carbohydrates provide 55-60% of the energy needed to maintain their normal
weight.
6. Seizures: Seizures may be due to the neuropathy caused by the disease itself orsecondary to the electrolyte abnormalities that may occur.
Recommended drug therapy:
- Clonazepam and Diazepam
7. Psychosis: chlorpromazine is suitable in the treatment of psychosis.
8. Correct electrolyte imbalances.
9. Investigate for and treat infections
Specific Treatment:
40% of Acute Attacks, especially those occurring in patients with Variegate Porphyria, will
resolve with supportive management alone. Patients with severe attacks, recurrent
episodes or patients that show no improvement after 24 hours require specific treatment.
1. Haem Arginate vs Haematin
Typically, haem therapy has been given in the form of hematite which consists of haem
dissolved in alkali. This solution, however, is unstable and rapidly decomposes. The
resultant degradation products are said to be responsible for some of the adverse
reactions seen with the use of Haematin. Haem complexed with the amino acid arginine
forms the stable compound: Haem araginate. Both Haematin and Haem arginate works
by replenishing haem stores and thereby inhibiting ALA synthetase by the negative
feedback mechanism. Further build up of porphyrins are therefore prevented.
Complications:
- Phlebitis at the site of injection has been reported with the use of Haem arginate: this
can be reduced by diluting the drug in human serum or human serum albumin which
acts as a protein buffer.
- Phlebitis has also been noted with the use of Haematin as well as dose-related,
reversible renal shutdown and thrombocytopenia and coagulopathy.
Disadvantages:
- Haem arginate is extremely expensive (currently costs around R20000 for 4 ampoules)
However, the dramatic clinical improvement and shortened hospital stay with a course of
haem arginate therapy as compared to long term hospitalisation and rehabilitation without
haem arginate, makes haem arginate highly cost effective.
Ways in which to minimise cost include:
- Reserving treatment for patients with severe acute porphyric attack, recurrent episodes
or no improvement after 24 hours, with conservative management. It is reasonable to
closely observe patients for 24 hours and treat with supportive measures before deciding
to commence treatment with Haem arginate.
- Using a standard dose of 5ml per dose (instead of the 3mg/kg/day advised on the
package insert). Each vial contains 10ml. The standard dose has been shown to be
effective.
- It is vitally important that haem arginate is given before neuropathy develops as it does
not reverse already established neuropathy.
- Haem arginate is not FDA approved.
- Haematin is extremely unstable.
