Surgical principals Flashcards
ASA grading
Class I : Normal Healthy
Class II : Mild systemic disease
Class III : Severe systemic disease that limits activities but not incapacitating
Class IV : Incapacitating disease that’s a constant threat of life
Class V : Moribund pt. not expected to survive ē / ē out an operation(ē in next 24hrs)
Special preparations for certain procedures
- Thyroid surgery; vocal cord check.
- Parathyroid surgery; consider methylene blue to identify gland.
- Sentinel node biopsy; radioactive marker/ patent blue dye.
- Surgery involving the thoracic duct; consider administration of cream.
- Pheochromocytoma surgery; will need alpha and beta blockade.
- Surgery for carcinoid tumours; will need covering with octreotide.
- Colorectal cases; bowel preparation (especially left sided surgery)
- Thyrotoxicosis; lugols iodine/ medical therapy.
When should you consider enteral feeding in surgical patient
Surgical patients due to have major abdominal surgery: if malnourished, unsafe swallow/inadequate oral intake and functional GI tract then consider pre operative enteral feeding.
Patients identified as being malnourished
AT RISK of malnutrition
* BMI < 18.5 kg/m2
* unintentional weight loss of > 10% over 3-6/12
* BMI < 20 kg/m2 and unintentional weight loss of > 5% over 3-6/12
At risk of malnutrition
* Eaten nothing or little > 5 days, who are likely to eat little for a further 5 days
* Poor absorptive capacity
* High nutrient losses
* High metabolism
Hypovolaemia, cariogenic and septic shock CO, PAOP, SVR
Hypo- low CO, PAOP, high SVR
Cardio- low CO, high PAOP, high SVR
Septic- high CO, low SVR, low PAOP
What is PAOP and how the results are interpreted
The pulmonary artery occlusion pressure is an indirect measure of left atrial pressure, and thus filling pressure of the left heart.
P AOP mmHg
Normal 8-12
Low <5 - hypovolaemia
Low with pulmonary oedema <5 - ARDS
High >18- overloaded
Types of surgical drains and their uses
CNS
* Low suction drain or free drainage systems may be used for situations such as drainage of sub dural haematomas.
CVS * Following cardiothoracic procedures of thoracic trauma underwater seal drains are often placed. When an air leak is present they may be placed on suction whilst the air leak settles
TNO
* In this setting drains are usually used to prevent haematoma formation (with associated risk of infection).
GI
* Surgeons often place abdominal drains either to prevent or drain abscesses, or to turn an anticipated complication into one that can be easily controlled such as a bile leak following cholecystectomy.
Causes of post op pyrexia
Day 1-2 – consider a respiratory source (or body’s routine response to surgery)
Atelectasis
Most common after midline laparotomies (pain impairs ventilation)
* Pyrexia usually mild and non swinging
Day 3-5 – consider a respiratory or urinary tract source
Usually occur in patients with indwelling urinary catheters
Day 5-7 – consider a surgical site infection or abscess/collection formation
Anastomotic leak
Swinging pyrexia
* Ileus
* Increasing abdominal pain
Any day post-operatively – consider infected IV lines or central lines as a source
Malignant hyperthermia causes , ix and tx
Causative agents
* Halothane
* Suxamethonium
* Other drugs: antipsychotics (neuroleptic malignant syndrome)
Investigations
* CK raised
* Contracture tests with halothane and caffeine
Management
* Dantrolene
Methods of sterilisation
-autoclave for most instruments
- endoscopy equipment cannot be sterilised by this method as it would damage it. Therefore they are sterilised using 2% glutaraldehyde solution.
Silk suture classification and uses
Biological, braided
Theoretically permanent although strength not preserved
Anchoring devices, skin closure
Catgut suture classification and uses
Biological Braided
Lasts 5-7d
Short term wound approximation
Not available in UK
PDS suture classification and uses
Synthetic Monofilament
Up to 3 months (longer with thicker sutures)
Widespread surgical applications including visceral anastomoses, dermal closure, mass closure of abdominal wall
Vicaryl suture classification and uses
Braided synthetic
Up to 6 weeks
Most tissues can be apposed using polyglycolic acid
Prolene suture classification and uses
Synthetic monofilament
Permanent
Widely used, agent of choice for vascular anastomoses
Ethibond suture classification and uses
Synthetic braided
Permanent
Used in laparoscopic surgery
Factors involved in choosing suture
Absorbable vs Non absorbable
Consider absorbable sutures in situations where long term tissue apposition is not required. In cardiac and vascular surgery non absorbable sutures are usually used.
Suture size
The higher the index number the smaller the suture i.e. : 6/0 prolene is finer than 1/0 prolene.
* Finer sutures have less tensile strength. For example 6/0 prolene would not be a suture suitable for abdominal mass closure but would be ideal for small calibre distal arterial anastomoses.
Braided vs monofilament
Generally speaking braided sutures have better handling characteristics than non braided. However, they are associated with higher bacterial counts. Braided materials are unsuitable for use in vascular surgery as they are potentially thrombogenic
Skin grafts and flaps
Split thickness skin grafts
* Superficial dermis remove
-Split thickness grafts are commonly used for skin defects that are too large for a full thickness graft.
* Thigh is the commonest donor site
- Dermatome is used to remove skin
larger areas that require cove
Full thickness grafts
Whole dermal thickness is removed
* Sub dermal fat is then removed and graft placed over donor site
Once the graft is harvested, there is no epidermis left behind at the donor site and therefore this site must be closed using suture
donor site must be closed directly. Only relatively small areas can therefore be taken and from regions with surplus skin
Skin Flap
A skin flap is where tissue is transferred from a donor site to recipient site along with its corresponding blood supply
Better cosmetic and reduced chance of failing in comparison to skin graft
Common donor and recipient sites for full thickness skin graft
Postauricular skin Face
Upper eyelid skin- Contralateral eye defect
Supraclavicular skin- Face
Flexural skin (e.g. antecubital fossa)- Hand surgery, flexion contractures
Thigh and abdominal skin - The palms of the hands or soles of the feet
Key points for vascular anastomosis
Always use non absorbable monofilament suture (e.g. Polypropylene).
- Round bodied needle.
- Correct size for anastamosis ( i.e. 6/0 prolene for bottom end of a femoro-distal bypass).
- Suture should be continuous and from inside to outside of artery to avoid raising an intimal flap
Gas and pressure in laparoscopic surgery
CO2
12-15mmHg
Instrument used to pneumoperitoneum in laparoscopic surgery
Verress needle
If BP drops in laparoscopic surgery what can you do first
Release air will often improve
Types of abdominal incisions
Midline incision
- Commonest approach to the abdomen
- Structures divided: linea alba, transversalis fascia, extraperitoneal fat, peritoneum
(avoid falciform ligament above the umbilicus) - Bladder can be accessed via an extraperitoneal approach through the space of
Retzius
Paramedian incision
* Parallel to the midline (about 3-4cm)
* Structures divided/retracted: anterior rectus sheath, rectus (retracted), posterior
rectus sheath, transversalis fascia, extraperitoneal fat, peritoneum
* Incision is closed in layers
Battle * Similar location to paramedian but rectus displaced medially (and thus denervated) * Now seldom used
Kocher’s
Incision under right subcostal margin e.g. Cholecystectomy (open)
Lanz
Incision in right iliac fossa e.g. Appendicectomy
Gridiron
Oblique incision centered over McBurneys point- usually appendicectomy (less cosmetically acceptable than Lanz)
Gable
Rooftop incision
Pfannenstiel’s
Transverse supra pubic, primarily used to access pelvic organs
McEvedy’s
Groin incision e.g. Emergency repair strangulated femoral hernia
Rutherford Morrison
Extraperitoneal approach to left or right lower quadrants. Gives excellent access to iliac vessels and is the approach of choice for first time renal transplantation.
Monopolar vs bipolar
Mono
The current flows through the diathermy unit into a handheld device that is controlled by surgeon.
* In cutting mode sufficient power is applied to the tissues to vaporise their water content.
* In coagulation mode the power level is reduced so that a coagulum is formed instead.
Bipolar
The electric current flows from one electrode to another however, both electrodes are usually contained within the same device e.g. a pair of forceps.
* The result is that heating is localised to the area between the two electrodes and surrounding tissue damage is minimised.
