Principles of surgical care Flashcards
System used to classify surgical risk
ASA risk classification
Categories of ASA risk
l - healthy ll - minor disease (mild HPT) lll- Sever non-incapacitating disease lV - Incapacitating systemic disease (heart failure) V - Moribund E - Emergency surgery
Only routine test required for GA
Hb
Urine - glucose and protein.
Pathophysiological response to surgery
- Increased sympathetic innervation (tachy and vasoconstiction)
- Increase glucagon and cortisol (gluconeogenesis)
- Aldosterone + ADH + RAAS = sodium and water retention
- Decreased insulin
- Increased metabolic rate and acute phase proteins
Mendelson’s syndrome
Chemical pneumonitis caused by aspiration during anaesthesia
Average maintenance fluid requirements
30ml/kg/24hrs
Name the four stages of shock
- Initial
- Compensatory
- Progressive
- Refractory
Types of shock
- Hypovolaemic
· Most common type
· Due to insufficient circulating volume, most commonly blood loss - Cardiogenic
· Failure of the heart to pump effectively
· Massive myocardial infarction, arrhythmias, cardiomyopathy, cardiac valve problems are
common causes
3. Distributive ‘Relative hypovolaemia’ as a result of dilation of blood vessels which diminishes the systemic vascular resistance · Septic shock — caused by overwhelming systemic infection · Anaphylactic shock ~ anaphylactic reaction to an allergen, antigen, drug · Neurogenic shock — trauma to spinal cord with loss of autonomic and motor reflexes
4. Obstructive The flow of blood is obstructed which impedes circulation · Cardiac tamponade · Tension pneumothorax · Massive pulmonary embolism · Aortic stenosis
Causes of cardiogenic shock
Massive myocardial infarction, arrhythmias, cardiomyopathy, cardiac valve problems
Causes of distributive shock
· Septic shock — caused by overwhelming systemic infection
· Anaphylactic shock - anaphylactic reaction to an allergen, antigen, drug
· Neurogenic shock — trauma to spinal cord with loss of autonomic and motor reflexes
Causes of obstructive shock
· Cardiac tamponade
· Tension pneumothorax
· Massive pulmonary embolism
· Aortic stenosis
What two major criteria must be met to diagnose septic shock?
Evidence of infection
Refractory hypotension
Which minor criteria must be met for diagnosis of septic shock
Two of the following:
Tachpnoea (>20) or pCO2 12
HR > 90
Temp 38
Most common cause of septic shock
endotoxin-producing gram-negative bacilli
Resus in septic shock must begin immediately when..
Hypotensive or metabolic acidosis or serum lactate >4 mmol/L
Treatment plan for septic shock
Oxygen administration/ airway support Volume resus Early antibiotics Rapid source identification Support major organs
Targets for volume resus in septic shock
CVP 8 - 12 mmHg MAP > 65 mmHg (adrenalin) Urine output > 0.5ml/kg/hr Haematocrit > 30% CV or mixed venous > 70% and 64% respectively
What connects the greater and lesser sacs of the peritoneal cavity?
Foramen of Winslow
Nerve supply of:
- Parietal peritoneum
- Visceral peritoneum
- Afferent somatic (localised sharp pain)
2. Afferent autonomic (poorly localised and dull) NB sensitive to distension/ischaemia but not temp and pain
Two clinical categories of peritonitis
1) Primary peritonitis is an infection of the peritoneum occurring de novo without obvious intra-abdominal
pathology.
2) Secondary bacterial peritonitis is a purulent inflammation of the peritoneum due to contamination following a complication of a preexisting primary intra-abdominal process such as perforated peptic
ulcer, ruptured appendix, a disrupted anastomotic suture line or as consequence of bacterial contamination from external sources (eg. penetrating injury).
In whom does spontaneous bacterial peritonitis occur?
Alcoholic cirrhosis with ascites (prognosis poor due to poor baseline)
Most common organisms in SBP?
E coli
pneumococci
Most common cause of secondary peritonitis
ruptured appendix / direrticuli
What can cause 2ndry peritonitis?
Primary abdo disease Trauma Obstruction Malignancy Perforated ulcer/appendix/diverticulus Bowel ischaemia PID Surgery (current or previous)
Most commonly cultured orgs in 2ndry bacterial peritonitis
E coli
B fragilis
What is the pathophysiology of bacterial peritonitis?
Fluid shift - from intravascular space to peritoneal space
Ileus
Endocrine - RAAS and Adrenal stimulation
CVS - Marked vasoconstiction -> lactic acid in peripheries -> metabolic acidosis which kidneys struggle to clear as prerenal failure
Resp - Increased demand and less space due to distension
Kidney - pre-renal plus sodium and water retention
Essential management steps in peritonitis
Fluid resus
Antibiotics
Decompensation of GIT
Exploratory laparotomy if required.
NB respiratory function must be monitored
Which antibiotics are used in peritonitis
Empiric triple therapy
Aminoglycosides - Gram negs (cleared renally {give third gen cefs} + ototoxicity)
Metronidazole - Anaerobes
Ampicillin - Enterococci
Intra-abdominal abscess formation is
due to either:
1. effective localization of the primary pathology such as an appendiceal or diverticular abscess 2. a sequel or complication following generalized peritonitis or 3. intraperitoneal contamination secondary to external trauma or complicating previous surgery
The major intraperitoneal anatomic spaces in which abscesses commonly localise are:
- Subphrenic space
- Subhepatic space (Morrison’s pouch)
3/4. Paracolic gutters - Interloop
- Appendiceal
- Pelvic
Most useful investigation to identify intraperitoneal abscess
U/S or CT
