Section 5 Flashcards
An 80-year-old gentleman presents for an elective repair of an 8 cm
infrarenal abdominal aortic aneurysm. You have been asked by surgeons to
review this patient in the preassessment clinic.
summarise the case.
This 80-year-old patient presents as a high-risk patient with multiple comorbidities for high-risk surgery. He is elderly with significant cardiac
history, poorly controlled hypertension, pre-existing moderate chronic kidney disease, and significant restrictive lung disease. The size of his aortic aneurysm and his poor physiological status puts him at increased risk of perioperative cardiac and surgical complications, bleeding, and long-term severe renal dysfunction.
I would like to take a full history, examination, and review and consider additional investigations and ensure full optimisation of his comorbidities before considering his options with both the patient and his surgeon
This 80-year-old patient presents as a high-risk patient with multiple
comorbidities for high-risk surgery.
Discuss assessment of risk.
- Abdominal aortic aneurysms are incidental findings in two thirds of patients.
- Surgery is recommended when they reach 55 mm. At this stage there is less than 1% risk of spontaneous rupture. By 60 mm there is more than 17% risk of spontaneous rupture. We can see that simply the size of this gentleman’s aneurysm places him at high risk from rupture without surgical interventionIn terms of proceeding with surgery, risk assessment should be done taking
into consideration the likelihood of a perioperative cardiovascular event. - original cardiovascular risk scoring systems include Goldman’s Criteria,
Detsky’s, and Lee’s Revised Cardiac Index. The American College of
Cardiology (ACC)/American Heart Association (AHA) guidelines for
Perioperative evaluation of Non-Cardiac Surgery (2003) have been developed subsequently.
Patient Risk (cardiac risk by
patient comorbidities)
• Minor
° Age > 70
° Abnormal ECG
° Nonsinus rhythm
° Uncontrolled hypertension
° Stroke
• Moderate
° MI > 6 months
° Mild angina
° Compensated heart failure
° Diabetes
• Major
° MI < 6 months
° Unstable angina
° Decompensated heart failure
° Severe valvular heart disease
° Symptomatic arrhythmias
surgical Risk (cardiac risk by
type of surgery)
• Minor (< 1%)
° Endoscopy/cataract surgery
° Plastics/breast surgery
• Intermediate (1%–5%)
° Thoracic/head and neck surgery
° orthopaedic/minor vascular surgery
• Major (> 5%)
° Aortic/major vascular surgery
° Emergency surgery
° Prolonged surgery
From a surgical risk basis, this is aneurysm surgery in the high-risk category
and independently, cardiac risk is more than 5% for undergoing surgery
alone irrespective of comorbidities.
In recent times it is apparent that more comprehensive scoring systems
are needed to categorise patient risk. A system known as EuroSCoRE is
increasingly being used.
could you go through his
investigations and positive
findings?
Bloods
His blood tests reveal that he has chronic kidney disease.
ecG
• PR interval is at the upper limit of normal (200 msec)
• Tall R waves in lateral leads V5 and V6 with mild ST segment depression
suggests left ventricular hypertrophy
• rSR pattern in V1 with T wave inversion in V1–V3, suggestive of right
bundle branch block
cXR
CXR reveals evidence of his previous surgery and signs within his
existing lung.
It demonstrates marked volume loss of the left hemithorax with shift of
the mediastinum and elevation of the hemidiaphragm. Also the pleura is
calcified.
Lung function test
Lung function tests reveal severe restrictive disease and a very low DLCo.
DLCo is a measurement of carbon monoxide take-up per unit time. It
measures alveolar/capillary function. DLCo < 80% is associated with
increased pulmonary complications, and a DLCo < 30% is associated with
increased morbidity.
A full history together with an echocardiogram and baseline ABGs would
help assess him further.
What methods are there for assessing his functional capacity?
- Functional capacity assesses patient response to increased physical
demand. - I would like to ask about his exercise tolerance. This can be done
by using the Duke Activity Status Index, which quantifies numbers of METs (metabolic equivalents), a measure of basal oxygen consumption (i.e. at rest). - one MET equates to 3.5 ml o2/kg/min.
7–10 METs suggests good function (e.g. carrying shopping upstairs, cycling, jogging).
4–7 METs suggests moderate function (e.g. climbing two flight of stairs without stopping).
1–4 METs suggests impaired function (e.g. basic ADLs, eating, dressing,
walking on flat surface). - tests of functional capacity
exercise ecG (Bruce Protocol): Looking for evidence of ischaemia while walking on a treadmill which goes through intervals of walking on a flat surface to graduated inclines. - 6-minute walk test: To record the furthest distance walked at own pace back and forth along a 30 m walkway in 6 minutes on a flat surface.
- incremental shuttle walk test: Externally paced, incremental distance walked back and forth, final result measured in this is the number of shuttles, which can help predict Vo2 max.
- Pharmacology-induced stress testing: Dobutamine Stress Echo, thallium scan; echocardiographic or nuclear medicine imaging changes based on drug injected to look for any regional wall motion abnormality or cold spots depending on the test. This may be useful if unable to walk due to arthritis or other conditions.
cardiopulmonary exercise testing (cPet) - This is usually done on a bicycle with assessment of both ECG and analysis of gases and is valuable in considering when the aerobic metabolism crosses over to anaerobic metabolism in a patient and assessing maximal
oxygen consumption at peak exercise. It provides many other parameters that can help uniquely assess cardio respiratory risk in combination.
How is eVAR performed?
Endovascular repair of abdominal aortic aneurysms involves a joint
procedure performed by a radiologist in conjunction with a vascular surgeon.
An aortic stent graft is placed via femoral arteries to extend both above and
below the edges of the aneurysm. one or both groins may be used. Local
anaesthetic is used for the entry site, but regional or general anaesthesia
may also be given, though less frequently. Arterial blood pressure monitoring
is ideal. It is not suitable if there is significant peripheral vascular disease or
atherosclerotic plaques.
What are the benefits of eVAR
versus open surgery?
Mortality of EVAR versus open repair is quoted as 0.9% versus 4.3%
according to AAAQIP report from 2009–2010.
Advantages
• Shorter, less invasive procedure
• Less associated bleeding
• Early ambulation
• Reduced hospital stay
Disadvantages
• Costly
• Technically difficult
• Reasonable incidence of poor seating of the graft and therefore leak
around the graft
How will you discuss risk with the patient?
- I would explain risk to the patient in terms of the patient’s comorbidities
and the surgery they are undergoing. - I will need a full history and possible additional investigations in order to provide a more comprehensive
picture. It is important to use terms that the patient can understand
such as percentages or use of ‘common’ or ‘rare’. - The Royal College of Anaesthetists has produced guidance and a patient information leaflet relating to aortic surgery that I could give the patient.
- In this case there is the risk of his age and comorbidities, which may lead him to a higher risk of a heart attack and chest infection around the time of his operation, the higher risk of bleeding given the size and length of operation, and the possibility of long-term dialysis. This should be balanced against his high risk of spontaneous rupture given the size of the aneurysm.
- It is important that all concerns are addressed before proceeding from both the anaesthetic and surgical side.
Despite his high risk, how would
you anaesthetise him? 80 YEAR OLD FOR AAA
I would give him a general anaesthetic. Ensure he has taken all his regular
medications except an ACE inhibitor preoperatively.
Preinduction
• Full noninvasive monitoring
• Awake mid-thoracic epidural after informed consent under aseptic technique
• Invasive arterial monitoring
induction
• Intubation with the use of high-dose opiate and propofol intravenous
induction with use of a muscle relaxant
• Central venous line for assessment of fluid status and provision of
vasopressors, blood, and multiple drugs if needed
• Cardiac output monitoring would also be helpful
• Maintaining his mean arterial pressure within 15% of his baseline where
possible will help reduce risk of hypoperfusion to organs
• Optimal positioning
• Fluid and body warmers and temperature monitoring
• Nasogastric tube to empty the stomach
During the operation he has a
massive bleed when the clamp is
released. How will you manage
this?
This will require good communication within the theatre team to avoid
adverse sequelae. The clamp should be reinstated and then both medical
and surgical aspects managed.
From a surgical perspective, it is important that there is no ongoing surgical
site bleeding and this should be addressed. The bleeding may have in part
been related to haemodynamic changes associated with the release of
the clamp. This can be minimised by giving a fluid bolus and maintaining
vascular tone with vasopressors when clamp is next released. It is also
important to ensure that the current bleed has been dealt with and blood
and other products transfused appropriately if needed and haemodynamic
parameters restored before a repeat attempt at releasing the clamp
Define massive transfusion,
products available, and transfusion
triggers for each product.
Massive transfusion occurs when there is more than 50% blood volume
transfused in 4 hours or 10 units in 24 hours. Products available are red
cells, fresh frozen plasma, platelets, and cryoprecipitate. Adjuncts include
fibrinolytics, such as tranexamic acid, aprotinin, recombinant factor 7, and
prothrombin concentrate.
The main principles are to recognise it early, maintain tissue perfusion and
oxygenation by considering oxygen delivery, arrest the cause of bleeding
(surgical versus coagulopathy), and use blood products appropriately and
in a timely fashion. Until bleeding is controlled, it is recommended to give
products in a ratio of 1:1:1 (red cells:FFP:platelets).
transfusion triggers during ongoing bleeding
Hb < 10
APTT > 1.5 times normal
Platelets < 50 or < 75 with ongoing haemorrhage
Fibrinogen < 1.5
other goals to achieve
Temperature > 36 degrees
Ionised Ca2+ > 1.1
pH > 7.2
What are his options for analgesia?
AAA open
In view of his poor lung function and undergoing a laparotomy, I feel that
a thoracic epidural is in his best interests. I will discuss the procedure with
the patient and make appropriate plans for removal later given perioperative
heparin use. This should be performed awake preinduction and should
facilitate postoperative deep breathing and together with regular chest
physiotherapy help reduce the risk of postoperative respiratory infection.
The alternative would be to perhaps perform transversus abdominis plane
blocks and use a fentanyl/morphine PCA with regular paracetamol. It should
be borne in mind that due to his age he is likely to be opiate sensitive and
due to his additional risk of further renal impairment postoperatively he
may have difficulty clearing opiates, which may impair his recovery and
cooperation with physiotherapy.
What will decide the criteria
for extubation at the end of the
operation and where will he go
postoperatively?
Providing he has normal acid base, temperature, reasonably corrected
haematological and electrolyte parameters and is fully reversed, it would be
ideal to plan for an early wakening and extubation to assess neurology and
encourage early chest physiotherapy. With his comorbidities, intensive care
would be necessary in the first instance until both ventilation and kidney
function have been assessed as adequate.
Preoperative cardiopulmonary exercise testing (CPET) may have helped plan
postoperative care if he has undergone this
can you discuss relevance of CPET in more depth with respect to elective AAA surgery?
- In recent years various studies have looked at the use of CPET to help
stratify risk in patients undergoing aneurysm surgery. - In the UK the national vascular society has recommended the use of the AAAQIP (Abdominal Aortic
Aneurysm Quality Improvement Project) preoperative care bundle (2011), which incorporates the following:
• Preoperative assessment and risk scoring
• CT angiography to aid decision making between open repair or EVAR
• Assessment by a vascular anaesthetist
• Case reviewed at an MDT meeting involving both surgeon and radiologist
• Patient to be given evidence-based written information CPET has become a routine part of preassessment for elective aneurysm surgery and helps plan postoperative care. Some variables of significance
are as follows. - VO2 max of 15 ml/kg/min is thought to be equivalent to four METs and hence predictive of poor functional capacity below this value. A value of at least 20 ml/kg/min is desirable for abdominal aortic aneurysm surgery.
- AT, or anaerobic threshold, denotes the VO2 value when there is a switch from aerobic to anaerobic metabolism and therefore when oxygen demand is greater than supply. An AT of 11 ml/kg/min is thought to be needed to undergo significant surgery, and below this there may be a need for
postoperative critical care. In addition, below this value on a case-by-case basis there may be a preference for EVAR instead of an open procedure. - A low-peak Vo2, AT, and ventilatory equivalent for Co2 have been shown to be associated with poor outcomes after this surgery.
A 19-year-old male who is normally fit and well has been booked for
repair of a fractured mandible. When you go to see him in the ward, you notice
that his breath smells strongly of alcohol.
What are your concerns?
• Mode of injury
• Loss of consciousness and current GCS
• Airway involvement
• Associated head and neck injuries
• Intoxication – alcohol, drugs
• Starvation status
How would you assess
the airway? facial trauma
Patients with facial trauma often pose the greatest airway challenges to the
anaesthetist.
For this patient with isolated facial trauma, preoperative airway evaluation
must be detailed and thorough.
• Particular attention should be focused on jaw opening, mask fit, neck
mobility, maxillary protrusion, macroglossia, dental pathology, nasal
patency, and the existence of any intraoral lesion or debris.
• Trismus is often caused by pain and can disappear on induction of
anaesthesia. However, it may persist for mechanical reasons and this
needs to be discussed with the surgical team.
• Preoperative imaging should be reviewed. X-ray of the mandible (AP,
lateral oblique, or panoramic) and neck (AP, lateral), CT if possible.
What are the possible associated
injuries?
• Cervical vertebrae fracture
• Head injury
• Airway: soft tissue injury with risk of oedema and obstruction, tracheal
injury
• Other facial fractures (i.e. nose, maxilla Le Fort fracture type I horizontal,
type II pyramidal, type III transverse)
What are Le Fort fractures? see Figure 5.3.
They are midfacial fractures caused by anteriorly directed force.
- In Le Fort I fractures, a horizontal fracture line separates the inferior portion of the maxilla from the superior two-thirds of the face, which remain associated with the skull. The entire maxillary dental arch may be mobile or wedged in a pathologic position.
- In Le Fort II fractures, the pyramidal mid-face is separated from the rest of the facial skeleton and skull base.
- In Le Fort III fractures, the face is essentially separated along the base of the skull due to force directed at the level of the orbit.
When are you happy to anaesthetise this patient? Facial fractures with alcohol intoxication.
- If the airway is not compromised and there is no associated head injury, I will anaesthetise him once he has sobered and achieved the starvation status.
- There are no other associated injuries, and the chance of head injury has been ruled out. He is presented for isolated mandible fracture.
How would you anaesthetise him? Facial fractures
• Prepare for a potential difficult intubation (i.e. senior help, skilled assistant, difficult airway trolley).
• The route of repair also needs consideration, as it can be intraoral, subconjunctival, or via a scalp flap.
• Induction: If any forewarning sign of problems with mask ventilation or endotracheal intubation is observed, the airway should be secured prior to anaesthesia induction. This process may involve fibreoptic nasal or oral
intubation or tracheostomy.
• Different endotracheal tubes (ETT) may be used: In this patient, after discussing with the surgeon for options, my consideration would be to use a nasal tube as this gives room in the mouth for the surgeons to work in. Also this will be beneficial in patients with malocclusion or wedge fracture where insertion of an oral ETT would have been challenging.
• The need for a throat pack, postoperative intermaxillary fixation, and facial nerve monitoring should also be discussed.
Isolated mandible fractures usually do not make intubation more difficult.
- However, if it is associated with other facial injuries, the airway might be more difficult to manage. In these cases an inhalational induction might be considered.
- Remember the risk of an association with a fracture of the base of the skull in which case the nasal route has to be avoided.
What are the nice guidelines regarding head injuries?
Assessment
• In patients with GCS 15, assessment is done within 15 min.
GCS 9–14 needs immediate assessment.
GCS < 8: anaesthetist should be involved.
investigation
• Exclude brain injury with CT scan before blaming the depressed level of consciousness on intoxication.
transfer
• Transfer to a tertiary centre would benefit if the patient has a GCS < 8 regardless of the need for surgery.
• If transfer is not possible, ongoing liaison with neuro unit is done for advice on management
A 75-year-old female patient, suffering from severe Rheumatoid
arthritis, is booked for a total knee replacement. Can you tell me the positive findings on her chest X-ray.
Bilateral airspace disease with:
• Extensive reticular change throughout both lungs
• Reduced volume
• Honeycomb pattern
• Shaggy heart border
Diagnosis: Pulmonary fibrosis. This can be because of the disease
progression or as a side effect of drugs for rheumatoid disease.
What does her c spine X-ray show? see Figure 5.5
Lateral radiograph of the neck with the head in flexion shows an increased distance between the anterior border of the dens and the posterior border of the anterior tubercle of C1. This “pre-dentate space,” should be less than 3 mm in the adult. Also there is forward suluxation of C1 on C2.
Mainly two types of changes might be seen: Atlanto-axial subluxation and
sub-axial subluxation.
Atlanto-axial subluxation
• Anterior: Most common (80%) finding in rheumatoid arthritis involving the neck, where C1 vertebra is moved forward on body of C2 vertebra due to damage to transverse ligament and can cause spinal cord compression by odontoid peg. Subluxation occurs when distance between atlas and odontoid is > 4 mm in adults and > 3 mm in children.
It is best seen in lateral neck X-ray with neck flexion (which makes
subluxation worse).
• Posterior: occurs in 5% of the patients and is due to destruction of
odontoid peg, which causes backward movement of C1 vertebra over C2 vertebra. It is best seen in lateral X-ray with neck extension, which makes the condition much worse.
- sub-axial subluxation It is not very common, occurs below C2 level, and can cause fixed flexion Deformity due to ankylosis and osteoporosis.
What is rheumatoid arthritis?
It is an autoimmune, systemic chronic inflammatory disease associated with:
• Polyarthritis of joints with pannus formation
• Synovitis of joints and tendon sheaths
• Loss of articular cartilage and erosion of bone and joint destruction
Women are affected more than men.
Age group is 30–55 years.
Seventy percent are HLA DR4 +ve & seropositive for rheumatoid factor.
What are the other system
manifestations in rheumatoid
arthritis?
Rs
• Pulmonary fibrosis, vasculitis
• Pulmonary hypertension, nodules
cVs
• Arteriosclerosis, MI, stroke
• Mitral valve disease, pericardial effusion, conduction defects
Blood
• Anaemia
nervous system
• Peripheral neuropathy
• Autonomic dysfunction
• Compression neuropathy, myelopathy
Renal
• Amyloid, nephropathy
Liver
• Felty’s syndrome
eye/skin
• Episcleritis, rheumatoid nodules, thin papery skin
Due to drugs
• NSAIDS—renal and GI impairment
• Methotrexate, gold, pencillamine—immunosuppression, pancytopenia,
liver and renal dysfunction
• Steroids—hypertension, osteoporosis
Joints
• Pain and morning stiffness due to inflammation of synovium
• Reduced bone density, cartilage loss
should you be worried about this
patient’s airway?
• Anterior or posterior subluxation and spinal cord compression
• Sub-axial subluxation—fixed flexion deformity
• TMJ involvement—reduced mouth opening
• Cricoarytenoid involvement—stridor
• Steroids—cause osteoporosis
How will you anaesthetise this patient?
Rheumatoid athritis for TKR
Regional anaesthesia in form of spinal is the best for this patient, if there is no absolute contraindication. It is also ideal from the surgical (enhanced recovery pathway in major arthroplasty) point of view.
Preassessment
• Routine anaesthetic history and examination
• Airway assessment—Mallampati assessment, thyromental distance, mouth opening, jaw protrusion, neck extension
• Drug history and its effect on various organ systems
investigations
• FBC, renal, and liver function tests to assess type of anaemia and for a baseline function
• Chest X-ray to look for pulmonary involvement
• Because of the nature and effect of the disease on cervical spine, lateral C spine X-ray is deemed necessary both in neck extension and flexion
view
• Routine ECG and echocardiography if any significant cardiac symptoms
investigations
• FBC, renal, and liver function tests to assess type of anaemia and for a baseline function
• Chest X-ray to look for pulmonary involvement
• Because of the nature and effect of the disease on cervical spine, lateral C spine X-ray is deemed necessary both in neck extension and flexion
view
• Routine ECG and echocardiography if any significant cardiac symptoms intraoperative
• Position during the procedure needs extra care and take precautions for pressure area to be protected to prevent any injury
• Full asepsis is maintained, as a general measure and also due to the state of immunocompromise in this group of patients
• Warming and fluid management to prevent any renal failure in the postoperative period
• Steroid replacement during surgery
• Good pain relief in postoperative period; exercise caution with the use of NSAIDs for fear of renal dysfunction and gastric ulcer
• Patient control analgesia may not be appropriate if hand deformities are present
Postoperative
• ITU/HDU care in patients with severe respiratory disease
• Early mobilisation and postoperative physiotherapy is useful in preventing postoperative respiratory and other complications
You are administering an epidural for labour analgesia in a 25-year-old
primigravida, with a 16 G Tuohy needle when a wet tap occurs.
What is your immediate course
of management?
• Resite: Take the needle out and reinsert in an adjacent space (OR)
• Spinal catheter: Insert the epidural catheter into the subarachnoid space
• General: document, explain to patient, explain to team
state the advantages and disadvantages of both techniques?
Reinserting epidural vs insertion of catheter into the subarachnoid space.
What special precautions would
you take if you had inserted a
spinal catheter?
• Labeling the catheter
• Handover to the team
• All top-ups given by the anaesthetist
• Regular neurological observations
• Aseptic precautions
What top-up would you give
if you were inserting a spinal
catheter?
2–3 mLs of the low dose mix (0.1% bupivacaine + 2mcg/mL fentanyl)
or 1 mL of 0.25% Bupivacaine +/− fentanyl 15–25 mcg
What is the chance of this
patient developing a post-dural
puncture headache (PDPH)?
There is a 80% chance of her developing PDPH as the Tuohy needle is
wide-bore needle
• 16 G: 80%
• 20 G: 40%
• < 25 G: 1%–2%
What are the risk factors
that predispose one to the
development of PDPH?
What is the differential
diagnosis of postpartum
headache?
What are your analgesic options
for a child who is booked for
hypospadias surgery?
Multimodal analgesia (WHo ladder)
• Simple analgesics
• NSAIDS
• Opioids—oral/IV
• Wound infiltration
• Nerve blocks—dorsal penile block/caudal block
What is the nerve supply of the
scrotum and penis?
scrotum
• Anterior 1/3—ilioinguinal nerve (L1)
• Posterior 2/3—perineal nerve (S2)
• Lateral—posterior cutaneous nerve of thigh (S3)
Penis
• Dorsal nerve of penis (S2,3,4)
• Ilioinguinal nerve (L1)
What are the differences in the
anatomy of the caudal epidural
space between adults and
children?
What is the phathogenesis of peeclamsia and description of its stages of development?
- Stage i Abnormal placentation and vascular remodeling decreased placental perfusion
Maternal factors
• Genetic
• Behavioral
• Environmental - Stage ii
Maternal syndrome of preeclampsia with endothelial dysfunction
Resulting endothelial dysfunction produces an imbalance of pro- and anti-angiogenic factors, with an increase in anti-angiogenic factors. It should be noted that these biomarkers do not have sufficiently high positive predictive value when used alone. - The maternal syndrome of preeclampsia is characterised by decreased perfusion due to vasospasm and activation of coagulation cascade with
microthrombi formation and end organ damage.
• Fluid shift: Leaky capillaries together with a low oncotic pressure result in a low intravascular volume and fluid shift into the interstitial compartment
• Vasoconstriction: The generalised vasoconstriction will mean increased systemic vascular resistance and in severe preeclampsia increased
pulmonary pressure; also renal, hepatic, and pancreatic dysfunction.
Vasospasm in the cerebral vasculature causes seizures and intracerebral bleeds.
• Decreased placental blood flow: The compromised placental blood flow will result in IUGR (intrauterine growth retardation), fetal distress, and the high blood pressure increases the risk of placental abruption
What risk factors are associated
with the development of
preeclampsia?
Why do TCA drugs cause arrhythmias and hypotension?
- Tricyclic antidepressants slow phase 0 of cardiac depolarisation by inhibiting sodium channels. The resulting delay in propagation of depolarisation in the atrioventricular node, His-Purkinje fibres, and ventricular myocardium leads to prolongation of the PR and QRS interval. Abnormal atrial and ventricular repolarisation may give rise to ECG changes mimicking myocardial infarction (ST segment elevation and T wave inversion).
- The blood pressure may be elevated in the early stages after overdose, presumably due to the inhibition of norepinephrine uptake. Subsequently, the blood pressure is reduced, often to very low levels and may be due to a number of causes. TCAs themselves can cause direct myocardial depression or it relates to relative volume depletion and α receptor blockade induced vasodilatation. Thus, it usually responds rapidly to intravenous fluids.
