General surgery Flashcards
COCP Rules for surgery
The COC should be stopped:
1) Four weeks before any major surgery (which includes operations lasting more than 30 minute), all surgery to the legs, or surgery that involves prolonged immobilization of a lower limb.
2) If emergency surgery or immobilization (such as for a leg fracture) is necessary
ASA Grading
ASA Classification (American society of anaesthesiologist) Definition Examples
ASA I A normal healthy patient
Healthy, non-smoking, no or minimal alcohol use
ASA II A patient with mild systemic disease Mild diseases only without substantive functional limitations. Examples include (but not limited to): current smoker, social alcohol drinker, pregnancy, obesity (30 < BMI < 40), well-controlled Diabetes Mellitus/Hypertension,Mild lung disease
ASA III A patient with severe systemic disease Substantive functional limitations; One or more moderate to severe diseases. Examples include (but not limited to): poorly controlled Diabetes Mellitus/Hypertension, COPD, morbid obesity (BMI 40), active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate reduction of ejection fraction, End Stage Renal Disease (ESRD) undergoing regularly scheduled dialysis, history (>3 months) of Myocardial infarction, Cerebrovascular accidents
ASA IV A patient with severe systemic disease that is a constant threat to life Examples include (but not limited to): recent (< 3 months) of Myocardial infarction, Cerebrovascular accidents, ongoing cardiac ischaemia or severe valve dysfunction, severe reduction of ejection fraction, sepsis, DIC, ARD or ESRD not undergoing regularly scheduled dialysis
ASA V
A moribund patient who is not expected to survive without the operation Examples include (but not limited to): ruptured abdominal/thoracic aneurysm, massive trauma, intra-cranial bleed with mass effect, ischaemic bowel in the face of significant cardiac pathology or multiple organ/system dysfunction
ASA VI A declared brain-dead patient whose organs are being removed for donor purposes
What happens if excess NaCl given post op
Hyperchloraemic acidosis
Propofol use
USe
Key features
Rapid onset of anaesthesia Pain on IV injection Rapidly metabolised with little accumulation of metabolites Proven anti emetic properties Moderate myocardial depression
Widely used especially for maintaining sedation on ITU, total IV anaesthesia and for daycase surgery
Sodium thiopentone use
Key features
Extremely rapid onset of action making it the agent of choice for rapid sequence of induction
Marked myocardial depression may occur
Metabolites build up quickly
Unsuitable for maintenance infusion
Little analgesic effects
Ketamine use
Key features
May be used for induction of anaesthesia
Has moderate to strong analgesic properties
Produces little myocardial depression making it a suitable agent for anaesthesia in those who are haemodynamically unstable
May induce state of dissociative anaesthesia resulting in nightmares
Drugs which impair wound healing
Non steroidal anti inflammatory drugs
Steroids
Immunosupressive agents
Anti neoplastic drugs
How is total parenteral nutrition delivered
The definitive option in those patients in whom enteral feeding is contra indicated
Individualised prescribing and monitoring needed
Should be administered via a central vein as it is strongly phlebitic
Long term use is associated with fatty liver and deranged LFT’s
Post op VTE prophlyaxis with LMWH duration for
Hip arthrplasty
knee arthroplasty
NOF fracture
Hip arthrplasty
- 28 days
knee arthroplasty
- 14 days
NOF fracture
- Until mobile
What is suxamthonium
MOA
Use
Side effects
on-competitive (or depolarising) muscle relaxant, which works by inducing prolonged depolarisation of the skeletal muscle membrane.
- Clinically, this manifests as fasciculations (a number of un-coordinated muscle contractions/twitches) which last for a few seconds before profound paralysis occurs. P
Use
- The muscle relaxant of choice for rapid sequence induction for intubation
Side effects
Malignant hyperthermia (Rx is dantrolene)
Hyperkalaemia (normally transient)
Contraindications
Suxamethonium is contraindicated for patients with penetrating eye injuries or acute narrow angle glaucoma, as suxamethonium increases intra-ocular pressure
Elective surgery
How long before to stop food and fluids
6 hours for food
2 hours for clear fluids
Patients taking long term prednisolone - how to manage during op?
As a rule of thumb:
Minor procedure under local: no supplementation required
Moderate procedure: 50mg hydrocortisone before induction and 25mg every 8h for 24h
Major surgery: 100mg hydrocortisone before induction and 50mg every 8h for 24h, thereafter halving dose every 24h until maintenance dose reached.
Prep for colonoscopy
Patient will require laxatives the day before the colonoscopy.
Patients are required not to eat for 24 hours before the examination
Post0op complications
Day 1-2: ‘Wind’ - Pneumonia, aspiration, pulmonary embolism
Day 3-5: ‘Water’ - Urinary tract infection (especially if the patient was catheterised)
Day 5-7: ‘Wound’ - Infection at the surgical site or abscess formation
Day 5+: ‘Walking’ - Deep vein thrombosis or pulmonary embolism
Any time: Drugs, transfusion reactions, sepsis, line contamination.
What is malignant hyperthermia
Causes
Investigations
Management
Condition often seen following administration of anaesthetic agents
Characterised by HYPERPYREXIA and muscle RIGIDITY
cause by excessive release of Ca2+ from the sarcoplasmic reticulum of skeletal muscle
associated with defects in a gene on chromosome 19 encoding the ryanodine receptor, which controls Ca2+ release from the sarcoplasmic reticulum
susceptibility to malignant hyperthermia is inherited in an autosomal dominant fashion
neuroleptic malignant syndrome may have a similar aetiology
Causative agents
halothane
suxamethonium
other drugs: antipsychotics (neuroleptic malignant syndrome)
Investigations
CK raised
contracture tests with halothane and caffeine
Management
dantrolene - prevents Ca2+ release from the sarcoplasmic reticulum
Laryngeal airway mask
Details
Use
When is it not suitable
Widely used
Very easy to insert
Device sits in pharynx and aligns to cover the airway
Paralysis not usually required
Commonly used for wide range of anaesthetic uses, especially in day surgery
Not suitable
- non fasted pts - Poor control against reflux of gastric contents
Not suitable for high pressure ventilation (small amount of PEEP often possible)
Eponymous signs
Rosvings Boas Murphys Cullens Grey turners
Rovsings sign- appendicitis
Boas sign -cholecystitis
Psoas sign - retrocaecal cholecystitis
Murphys sign- cholecystitis
Cullens sign- pancreatitis (other intraabdominal haemorrhage)
Grey-Turners sign- pancreatitis (or other retroperitoneal haemorrhage)
Psoas sign = Acute retrocaecal appendicitis is indicated when the right thigh is passively extended with the patient lying on their side with their knees extended
Boas sign = In acute cholecystitis there is hyperaesthesia beneath the right scapula. Because bdominal wall innervation of this region is from the spinal roots that lie at this level
What is cryptoorchidism
Risks
Management
A congenital undescended testis is one that has failed to reach the bottom of the scrotum by 3 months of age
Risks
Infertility
Testicular torsion
Testicular cancer
Management
- Orchidopexy at 6- 18 months of age. The operation usually consists of inguinal exploration, mobilisation of the testis and implantation into a dartos pouch.
- Intra-abdominal testis should be evaluated laparoscopically and mobilised. Whether this is a single stage or two stage procedure depends upon the exact location.
- After the age of 2 years in untreated individuals the Sertoli cells will degrade and those presenting late in teenage years may be better served by orchidectomy than to try and salvage a non functioning testis with an increased risk of malignancy.
Classification of haemorragic shock
Class 1 = <750ml blood loss <15% blood loss Pulse <100 BP N RR: 14-20 UO >30ml Symptoms normal
Class 2 = 750-1500ml blood loss 15-30% blood loss Pulse >100 BP N RR: 20-30 UO: 20-30 Symptoms: Anxious
Class 3 = 1500ml - 2000ml 30-40% blood loss Pulse >120 BP low RR: 30-40 UO: 5-15 Symptoms: Confused
Class 4 = >2000ml blood loss >40% blood loss Pulse >140 BP low RR >35 UO <5ml Symptoms: Lethargic
Management
When assessing trauma patients it is worth remembering that in order to generate a palpable femoral pulse an arterial pressure of >65mmHg is required.
Once bleeding is controlled and circulating volume normalised the levels of transfusion should be to maintain a Hb of 7-8 in those with no risk factors for tissue hypoxia and Hb 10 for those who have such risk factors.
Assessment of upper GI bleed -scoring systems
Blatchford - if inpatient stay needed and OGD
Looks at
- Hb
- serum urea
- pulse rate
- blood pressure. Those patients with a score of 0 are low risk, all others are considered high risk and require admission and endoscopy.
Rockall - after endoscopy: to determine their risk of rebleeding and mortality.
- A score of 3 or less is associated with a rebleeding rate of 4% and a very low risk of mortality and identifies a group of patients suitable for early discharge.
Fluid resuscitation indication for burns
15% total body area burns in adults (>10% children)
The main aim of resuscitation is to prevent the burn deepening
Most fluid is lost 24h after injury
First 8-12h fluid shifts from intravascular to interstitial fluid compartments
Therefore circulatory volume can be compromised. However fluid resuscitation causes more fluid into the interstitial compartment especially colloid (therefore avoided in first 8-24h)
Protein loss occurs
Parkland formula (CRYSTALLOID) Total fluid requirement in 24 hours = 4 ml x (total burn surface area (%)) x (body weight (kg)) 50% given in first 8 hours 50% given in next 16 hours
After 24 hours
- Colloid infusion is begun at a rate of 0.5 ml x(total burn surface area (%))x(body weight (kg))
- Maintenance crystalloid (usually dextrose-saline) is continued at a rate of 1.5 ml x(burn area)x(body weight)
- Colloids used include albumin and FFP
- Antioxidants, such as vitamin C, can be used to minimize oxidant-mediated contributions to the inflammatory cascade in burns
- High tension electrical injuries and inhalation injuries require more fluid
- Monitor: packed cell volume, plasma sodium, base excess, and lactate
Splenic trauma management
Conservative
- Small subcapsular haematoma
- Minimal intra abdominal blood
- No hilar disruption
Laparotomy with conservation
- Increased amounts of intraabdominal blood
- Moderate haemodynamic compromise
- Tears or lacerations affecting <50%
Resection
- Hilar injuries
- Major haemorrhage
- Major associated injurie
What is flail chest
Multiple rib fractures with > or = 2 rib fractures in more than 2 ribs is diagnosed as a flail chest. This is associated with pulmonary contusion.
- Abnormal chest movement
- Avoid over hydration and fluid overload
Best imaging in anal fistula
Types
MRI
Types Enterocutaneous Enterocolic Enterovaginal Enterovesicular
Preparing for blood loss in surgery
Hysterectomy, appendicectomy, thyroidectomy, C section, lap chole
Salpingectomy for ruptured ectopic pregnancy, total hip replacement
Total gastrectomy, oophorectomy, oesophagectomy
Elective AAA repair, cystectomy, hepatectomy
Hysterectomy, appendicectomy, thyroidectomy, C section, lap chole
- G&S
Salpingectomy for ruptured ectopic pregnancy, total hip replacement
- Cross match 2 units as likely blood loss
Total gastrectomy, oophorectomy, oesophagectomy
Elective AAA repair, cystectomy, hepatectomy
- Crossmatch 4-6 units as blood loss definite
Lidocaine
Use
Excretion
Toxicity
Drug interactions
Lidocaine
An amide
Use
Local anaesthetic and a less commonly used antiarrhythmic (affects Na channels in the axon)
Hepatic metabolism, protein bound, renally excreted
Toxicity:
due to IV or excess administration. Increased risk if liver dysfunction or low protein states. Note acidosis causes lidocaine to detach from protein binding.
- Local anesthetic toxicity can be treated with IV 20% lipid emulsion
Drug interactions: Beta blockers, ciprofloxacin, phenytoin
Features of toxicity: Initial CNS over activity then depression as lidocaine initially blocks inhibitory pathways then blocks both inhibitory and activating pathways. Cardiac arrhythmias.
Increased doses may be used when combined with adrenaline to limit systemic absorption.
Bupivacaine
MOA
Use
Toxicity
Bupivacaine binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells, which prevents depolarization.
Use
It has a much longer duration of action than lignocaine and this is of use in that it may be used for topical wound infiltration at the conclusion of surgical procedures with long duration analgesic effect.
Toxicity
It is cardiotoxic and is therefore contra indicated in regional blockage in case the tourniquet fails.
Levobupivicaine (Chirocaine) is less cardiotoxic and causes less vasodilation.
Cocaine use in surgery
Toxicity
Pure cocaine is a salt, usually cocaine hydrochloride. It is supplied for local anaesthetic purposes as a paste.
Use
It is supplied for clinical use in concentrations of 4 and 10%. It may be applied topically to the nasal mucosa. It has a rapid onset of action and has the additional advantage of causing marked vasoconstriction.
Toxicity
It is lipophillic and will readily cross the blood brain barrier. Its systemic effects also include cardiac arrhythmias and tachycardia.
Apart from its limited use in ENT surgery it is otherwise used rarely in mainstream surgical practice.
Prilocaine Use
Similar mechanism of action to other local anaesthetic agents. However, it is far less cardiotoxic and is therefore the agent of choice for intravenous regional anaesthesia e.g. Biers Block.
Use of adrenaline in anaesthesia?
Adrenaline may be added to local anaesthetic drugs. It prolongs the duration of action at the site of injection and permits usage of higher doses (see above).
Contraindication
It is contra indicated in patients taking MAOI’s or tricyclic antidepressants.
Toxicity
The toxicity of bupivacaine is related to protein binding and addition of adrenaline to this drug does not permit increases in the total dose of bupivacaine, in contrast to the situation with lignocaine.
Most important thing to check in post op ileus
Mg and phosphate
Light-headiness, circumoral numbness and a metallic taste in her mouth. She then becomes hypotensive and bradycardia before having a cardiac arrest
Which anaesthetic caused this
Management
Caused by LA e.g. lidnocaine
Management
IV 20% lipid emulsion
Post op pyrexia causes
Early causes of post-op pyrexia (0-5 days) include:
- Blood transfusion
- Cellulitis
- Urinary tract infection
- Physiological systemic inflammatory reaction (usually within a day following the operation)
- Pulmonary atelectasis - this if often listed but the evidence base to support this link is limited
Late causes (>5 days) include:
- Venous thromboembolism
- Pneumonia
- Wound infection
- Anastomotic leak
When considering causes of post-op pyrexia, it is helpful to consider the memory aid of ‘the 4 W’s’ (wind, water, wound, what did we do? (iatrogenic
WHO pain ladder
1) Peripherally acting drugs such as paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs) are given.
2) If pain control is not achieved, the second part of the ladder is to introduce weak opioid drugs such as codeine or dextropropoxyphene together with appropriate agents to control and minimise side effects.
3) The final rung of the ladder is to introduce strong opioid drugs such as morphine. Analgesia from peripherally acting drugs may be additive to that from centrally-acting opioids and thus, the two are given together.
Spinal anaesthesia
Use
Length of action
Side effects
rovides excellent analgesia for surgery in the lower half of the body and pain relief can last many hours after completion of the operation if long-acting drugs containing vasoconstrictors are used.
Side effects of spinal anaesthesia include: hypotension, sensory and motor block, nausea and urinary retention.
Epidural anaesthsia
Side effects/ disadvantages
Contraindications
An indwelling epidural catheter inserted. This can then be used to provide a continuous infusion of analgesic agents. It can provide excellent analgesia. They are still the preferred option following major open abdominal procedures and help prevent postoperative respiratory compromise resulting from pain.
Disadvantages of epidurals is that they usually confine patients to bed, especially if a motor block is present. In addition an indwelling urinary catheter is required. Which may not only impair mobility but also serve as a conduit for infection.
- Epidural haematoma is a recognised complication.
They are contraindicated in coagulopathies.
Neuropathic pain management
First line: Amitriptyline (Imipramine if cannot tolerate) or pregabalin
Second line: Amitriptyline AND pregabalin
Third line: refer to pain specialist. Give tramadol in the interim (avoid morphine)
If diabetic neuropathic pain: Duloxetine
Warfarin high INR management
Major bleeding
- Stop warfarin
- Give intravenous vitamin K 5mg
- Prothrombin complex concentrate - if not available then FFP*
INR > 8.0 with Minor bleeding
- Stop warfarin
- Give IV vitamin K 1-3mg
- Repeat dose of vitamin K if INR still too high after 24 hours
- Restart warfarin when INR < 5.0
INR > 8.0 No bleeding
- Stop warfarin
- Give vitamin K 1-5mg by mouth, using the intravenous preparation orally
- Repeat dose of vitamin K if INR still too high after 24 hours
- Restart when INR < 5.0
INR 5.0-8.0 Minor bleeding
- Stop warfarin
- Give IV vitamin K 1-3mg
- Restart when INR < 5.0
INR 5.0-8.0 No bleeding
- Withhold 1 or 2 doses of warfarin
- Reduce subsequent maintenance dose
