S8) Abdominal Catastrophes Flashcards
What is an abdominal catastrophe?
An abdominal catastrophe is an event within or behind the abdominal cavity that poses an imminent threat to life
What is referred pain?
Referred pain is pain perceived at a site distant from the site causing the pain
What is somatic referred pain?
Somatic referred pain is pain caused by a noxious stimulus to the proximal part of a somatic nerve that is perceived in the distal dermatome of the nerve
How does visceral referred pain occur?
Visceral referred pain occurs when visceral afferent pain fibres (thorax and abdomen) follow sympathetic fibres back to the same spinal cord segments that gave rise to the preganglionic sympathetic fibres
What causes visceral pain?
- Abnormally strong muscle contraction and stretch
- Inflammation
- Ischaemia
Identify the three common regions where visceral pain is felt
Where is gastric and duodenal pain felt?
Where is gallbladder pain felt?
Where is splenic pain felt?
Where is pain due to acute appendicitis felt?
Where is pancreatic and abdominal aorta pain felt?
Where is small bowel colic felt?
Where is large bowel colic felt?
Where is renal/ureteric colic felt?
Where is pain due to peritonitis felt?
In terms of pain, how do patients with peritonitis present?
- Severe pain all over abdomen
- Pain may be referred to shoulder tips
- Shallow rapid breathing (diaphragmatic and abdominal wall movement)
- Very tender abdomen (on examination)
- ‘Rebound tenderness’ (early stages)
Explain why an inflamed peritoneal cavity can exude litres of fluid
- Large surface area
- Fluid can collect in abdomen
- Perfusion rate can increase
In a bowel obstruction, dehydration and increased haematocrit occur due to increased fluid loss.
Why is this?
- Accumulation of fluids
- Increased secretion
- Decreased reabsorption
In four steps, explain why several patients with bowel obstructions are in hypovolaemic shock at the time of presentation
⇒ 3-4 L of isotonic fluid sequesters in gut
⇒ Vomiting begins & fluid is lost
⇒ More space for fluid to sequester
⇒ Hypovolaemic shock (±7 litres lost)
Identify 2 useful indicators of dehydration in the context of bowel obstruction
- Raised haematocrit (>55%)
- Raised serum urea
Identify 5 types of abdominal catastrophes
- Blood loss
- Perforation of a viscus (inflammation, hypovolaemia, sepsis)
- Acute pancreatitis
- Acute cholangitis
- Acute gut ischaemia
Where is blood lost to in an abdominal catastrophe?
- Into the gut
- Into the retroperitoneum
- Into the peritoneal cavity
Identify three common causes of bleeding into the gut and briefly describe how they present
- Bleeding oesophageal varices (haematemesis and melaena)
- Bleeding peptic ulcer (haematemesis and melaena)
- Bleeding diverticular disease (haematochezia)
What is haematemesis?
Haematemesis is the vomiting of blood
What is haematochezia?
Haematochezia is bright red bleeding from the rectum, often seen with/in stools
What do haematemesis and haematochezia indicate?
Patient is bleeding massively from the upper GI tract
What is melaena?
Melaena is the passage of black tarry stools
What causes melaena and when does it occur?
- Caused by alteration of blood by digestive enzymes and intestinal bacteria
- Occurs with bleeding anywhere from the mouth to caecum
Patients taking oral iron have black stools.
What is the difference between this and melaena?
The smell will reveal the difference
How do bleeding duodenal ulcers present?
Bleeding duodenal ulcers nearly always present as a posterior duodenal ulcer that has eroded into the gastroduodenal artery
Why is serum urea a helpful indicator of upper GIT bleeding?
- Patients bleeding from the stomach/oesophagus present a large protein meal to the small bowel where it is converted by the liver into urea
- A rise in serum urea with a normal serum creatinine indicates: the source & magnitude of the bleeding
What are the two commonest causes of retroperitoneal bleeding?
- Ruptured abdominal aortic aneurysm (AAA)
- Patients on anticoagulants may bleed from torn retroperitoneal veins
Describe the typical presentation of a ruptured AAA
- Sudden death (50%)
- Sudden onset of severe abdominal, back or loin pain
- Sudden collapse
- Hypovolaemic shock
Briefly outline the outcome of a ruptured AAA
- Overall survival is about 17% (hospital, operation, recover)
- Overall mortality is 83% (sudden death/multi-organ failure in ITU)
How does ectopic pregnancy present in women of reproductive age?
- Lower abdominal pain
- Vaginal bleeding
- Collapse
- Left shoulder tip pain on lying down
What are the two commonest causes of perforation of the viscus?
- Perforated peptic ulcer
- Perforated diverticular disease
What are the two types of perforated peptic ulcers?
- Anterior perforated duodenal ulcer (more common)
- Posterior perforated gastric ulcer
What are the effects of the posterior perforation of a gastric ulcer?
- Initially allows gastric contents to enter the lesser sac
- Then fluid can track into the greater sac via the epiploic foramen
State the respective complications of perforated peptic ulcerations and perforated diverticular disease respectively as well as their associated mortality rates
- Perforated peptic ulceration leads to a chemical peritonitis (mortality 10%)
- Perforated diverticular disease leads to peritoneal sepsis and septicemia (mortality rate 50%)
What is a major clinical indicator of perforated viscus?
Pneumoperitoneum
Which two abnormalities must be corrected before the administration of anaesthesia?
- Potassium imbalances (hyperkalaemia & hypokalaemia)
- Fluid and electrolyte imbalances
Why must potassium imbalances be corrected before the administration of anaesthesia?
Many anaesthetic agents affect cardiac muscle/conduction function
Why must electrolyte and fluid imbalances be corrected before the administration of anaesthesia?
- Anaesthetic agents dramatically reduce sympathetic tone & have a negative inotropic effect
- In a patient who is dehydrated the SNS is maximally activated to maintain vital organ perfusion & hence could develop hypotension and possible die
Identify 4 causes of obstruction to the small bowel
- Adhesions due to previous surgery
- Femoral/inguinal hernia
- Volvulus
- Carcinoma of the caecum
Identify 3 causes of obstruction to the large bowel
- Carcinoma (particularly left-sided)
- Sigmoid volvulus
- Diverticular disease
What is the end result of a bowel obstruction?
- Isotonic hypovolaemia
- Hypochloremia
- Hypokalemia
- Metabolic alkalosis
In 4 steps, describe how bowel obstructions lead to metabolic alkalosis and hypokalaemia
⇒ Vomiting leads to loss of H+ and Cl-
⇒ Metabolic alkalosis
⇒ Renal compensation preserves H+ at the expense of K+
⇒ Hypokalemia ensues
What is acute pancreatitis?
Acute pancreatitis is a clinical condition involving the autodigestion by proteases of the retroperitoneum
Describe the aetiology of acute pancreatitis
- Alcohol
- Gallstones
Describe the management of acute pancreatitis
- No specific treatment
- Supportive management (fluid resuscitation & pain relief)
What can be used to diagnose acute pancreatitis?
Raised serum amylase
What is the commonest cause of acute gut ischaemia?
Embolism (atrial fibrillation)
How do patients with acute gut ischaemia present?
- Severe abdominal pain
- Tender over ischaemic gut (on examination)
- Patients rapidly become ‘toxic’ and hypotensive
How can acute gut ischaemia be diagnosed?
Very high white cell count >20 x109/l (normal – 4-11/l)
What is the treatment for acute gut ischaemia?
Urgent laparotomy and resection of dead bowel
What is acute cholangitis?
Acute cholangitis is a clinical condition involving an infection in the bile ducts
What is the commonest cause of acute cholangitis?
Obstruction of the common bile duct by the gallstone, leading to jaundice and biliary stasis
What is the commonest causative organism in acute cholangitis?
E.Coli
