Surgery Flashcards
What are the risk factors for AAA?
- male
- age > 65
- smoking
- hypertension
- myocardial and/or cerebrovascular disease
- genetic / familial e.g. inherited CT disorders such as Marfans and Ehlers-Danlos
How does a ruptured AAA present?
Most rupture into the RP cavity resulting in classic triad of:
- pain -> severe and usually in the back
- circulatory compromise
- pulsatile abdominal mass
Also - back pain mimicking renal colic, pain radiating into legs, chronic severe back pain (contained rupture), transient lower limb paralysis
What is the management of a patient with ruptured AAA?
Resus - 2 x large IV access
Massive transfusion protocol
Aim SBP 90
Analgesia
Bloods - FBC/u+es/coag/venous gas
ECG
Emergent transfer to operating theatre
How might a AAA be imaged?
- CT - good in uncertain diagnosis, gives details analysis and localise morphology. Can delay surgery, nephrotoxic contrast.
- US - rapid bedside confirmation
- MRI - not appropriate in rupture
How can you prognosticate in ruptured AAA?
- Hardman index
- Glasgow aneurysm score
Describe the Hardman index
Predicts immediate outcome after ruptured AAA surgery
- age > 76 = 1 point
- Cr > 190 = 1 point
- Hb < 90 = 1 point
- MI on ECG = 1 point
- LOC after arrival in hospital = 1 point
Scores of 2+ predict a mortality of 80%
Describe the Glasgow aneurysm score
Age = age in years
Shock +17 points
Myocardial disease = 7 points
Cerebrovascular disease incl TIA = 10 points
Ur > 20 +/or Cr > 150 = 14 points
A value of 84 = predicted mortality of 65%
What are the complications following emergency surgery for ruptured AAA?
Graft-related: early
- massive transfusion
- Distal embolisation
- Aortic branch involement causing ischaemia e.g. pancreatitis, AKI
- Endoleak
Non-graft related: early
- AKI, MI, paraplegia, hepatic dysfunction, HAP/VAP, ARDS, ACS, ileus
Late complications
- infected graft, graft occlusion, aorto-enteric fistula, anastomotic pseudoaneurysm, prolonged resp wean, small bowel obstruction, sexual dysfunction, incisional herniae, DVT/PE
What are the indications for spinal drain insertion in AAA?
- Reducsed CSF pressure following complex abdo EVARS where patients are considered high risk of spinal cord ischaemia
- Rescue therapy for delayed paraplegia post-op
How do lumbar drains work?
Cord perfusion pressure = MAP - CSF pressure
Therefore cord perfusion can be increased by decreasing the CSF pressure
What are the CIs to spinal drain insertion?
- Anticoagulation and coagulopathy
- Active infection (systemic or local)
Raised ICP
How to manage CSF drainage from a spinal drain
Most people produce 10-20mls/hour
- Target CSF pressure = 10
- Don’t drain too quickly - increases ICH - 5mls-10mls alloquots
- MAP target 85-90
- Aiming SCPP 75mmHg
What is normal IAP?
5-7mmHg
What is abdominal perfusion pressure?
MAP - IAP
What id intra-abdominal hypertension?
Sustained or repeated elevations in IAP > 12mmHg
What is abdominal compartment syndrome?
Sustain IAP > 20mmHg that is associated with new organ dysfunction
What is the grading of intra-abdominal hypertension?
Grade 1 = 12-15mmHg
Grade 2 = 16-20mmHg
Grade 3 = 21-25mmHg
Grade 4 = 26+mmHg
What are the risk factors for developing ACS?
- Reduced abdominal compliance
- abdo surgery with tight closure
- trauma, burns, obesity
- prone positioning - Increased abdo contents
- ileus, gastroparesis, psuedo-obstruction, ascites, haemoperitoneum - Capillary leak
- severe sepsis, trauma, pancreatitis, burns
-hypothermia
- acidosis
- massive transfusion
- fluid resus,+ve FB - Other / misc
- MV
- PEEP > 10cmH2O
- Increased head of bed angle
- Shock or hypotension
How is intra-abdo pressure measured?
- Direct - via needle into abdomen e.g. during laparoscopy
- Indirect - transduction of an intra-abdo viscus e.g. bladder. Zero at symphysis pubis
What are the pathological effects of ACS on the resp system?
- Basal atelectasis and collapse due to diaphragm splinting and reduced chest wall and lung compliance
- Increased V/A mismatch, hypoxia and hypercapnia
- Application of PEEP worsens venous return and cardiac output
What are the pathological effects of ACS on the CV system?
- Raised IAP is transmitted to the abdo vasculature
- Reduced CO due to reduced venous return and increased afterload
- Reduced CO further reduces APP
- Increased intra-thoracic pressure due to diaphragm splinting may compromise CO further
What are the pathological effects of ACS on the neurological system?
- Increased ICP can occur due to impeded venous return due to raised intra-thoracic pressure
- ICP may be further elevated due to cerebral vasodilatation due to hypoxaemia and hypercapnia
What are the pathological effects of ACS on the renal system?
- Reduced renal blood flow due to transmission of raised IAP to the renal vasculature
- The raised IAP is also transmitted to the renal outflow tract increasing pressure on the tubules and reducing filtration gradient
- Compensatory activation of the RAAS further worsens renal insult
What are the pathological effects of ACS on the GI and hepatic system?
- Hypoperfusion caused by critical illness is exac by venous hypertension, which results in bowel wall oedema
- This may cause bowel ischaemia and bacterial translocation
- Reduced flow in the hepatic vessels contributing to liver dysfunction
- Biliary sepsis resuting from increased pressure within the biliary tree
What are the principles of managing abdominal compartment syndrome?
- Medical management to reduce IAP - sedation, analgesia, muscle relaxant, avoid prone position
- Optimise fluid and correct +ve FB
- Evacuation of intraluminal contents - gastric decompression, prokinetics and laxatives
- Evacuation of abdo fluid collections - abscess drainage, paracentesis
- Organ support
- Surgical decompression
What are the complications / issues with an open abdomen?
- Nursing issues - skin prone to damage, issues with turning, pain
- Fluid loss - can be litres/day, unreliable fluid balance
- Malnutrition - protein/nitrogen loss from the open abdomen
- Infection risk - sterilty is almost impossible
- Visceral injury and adhesions
- Ileus
- Abdominal wall-related - large ventral hernias following definitve closure, inability to definitvely close
- Significant risk of enterocutaneous fistulation
Who benefits from surgical fixation of rib fractures?
- Pts with resp failure secondary to flail chest
- Thos with 3+ rib#s, at leadt 50% displaced and mod pulmonary dysfunction
- Over 80s with mod-to-severe rib#s (60% reduction in mortality)
- Those with TBI and chest wall injury
- Those unable to wean from MV due to pain a/w chest wall injury
When is the best time to fix ribs?
Earlier ops (<72hours) are shorter, involve less blood loss, have a reduced need for post-op MV, reduced pneumonia and reduced hosp/ICU LOS
