Suture Technique - Knot tying, suture patterns, and hemostasis Flashcards
Knot security is determined by:
- Size and structure of the suture material
- Coefficient of friction - the higher the coefficient of friction, the stronger the knot (silk - strong knots)
- Length of cut ends
- Quality of the knot - surgeon dependent
Knot Tying Technique and what to avoid
- Pull the suture ends in opposite directions at uniform rate and with equal tension
- Avoid:
- Creating friction between the strands while tightening the throw
- Crimping suture with instruments
4 throws = how many knots?
2 knots
3 throws are as secure as 6 for most sutures tested, but tensile failure load is greater with __
6
Recommendations:
Interrupted pattern’
Continuous Pattern, beginning and end
- Interrupted patter - 4 throws (2 square knots)
- Continuous pattern - 6 throws (3 square knots)
Where do sutures almost always fail? Why?
at the knot, unless the suture has been damaged; knotting reduces strength by 10-40%
- Simple knot
- Aka - throw
- One throw = simple knot
Square knot - it takes two throws to make a square knot
Surgeon’s knot - two wraps around first throw; second throw of a square knot goes ontop
Half-hitch knot - jerk up on one strand, usually done with a square knot ontop
Granny knot - BAD
Burying the knot - indications
- Inverted knot reduces likelihood that suture ends will become exposed
- Indications:
- Subcutaneous sutures
- Intradermal pattern
Principles of wound closure
- Closure should be as anatomic as possible (like tissues are apposed)
- Use the least amount of suture material that will accurately and reliably appose the tissues
- Dead space should be minimized
- Use absorbable material for buried sutures whenever possible - some excetions
“Routine” Wound Closure - what layers are usually included (ex - abdominal incision)
- Fascia - want to use longer acting suture material becuase it takes a long time to heal (PDS)
- Subcutaneous tissue
- Skin
What is the most common pattern with suturing subcutaneous tissue? And what can be done to decrease “dead space”?
- Simple continuous pattern
- Periodic bites into the underlying fascia can be sued to decrease “dead space”
Subcutaneous pattern
- Can be used for animals with a lot of subcutaneous fat
- Bites taken perpendicular to skin edge, but no dermis engaged
Intradermal pattern (aka ____)
- Subcuticular pattern
- More accurate apposition of skin edges - engages dermis
- bites taken perpendicular or parallel to skin edge
- Skin sutures may not be needed
- Continuous pattern
- Slightly overlapping bites (<25%) results in tighter closure
Perpendicular bites vs Parallel bites
- Thick skin - perpendicular to the incision
- Thin skin - parallel to the incision
- Skin suture guidelines
- distance between sutures should be:
- Distance between skin suture and wound edge should be:
- 2 times the skin thickness
- 5mm rule - you don’t want any skin suture less than 5mm from the wound endge becuase any less will compromise blood supply
Interrupted suture patterns: pros and cons
- Advantages
- Precise placement and control of tension
- Failure of one suture or knot inconsequential
- Disadvantages:
- Increased surgical time
- Increased volume of suture left in the wound
- Poor suture economy
Continuous Suture Patterns
- Advantages:
- Speed of placement
- Less suture left in wound
- More air- or water-tight
- Good for urinary bladder and stomach
- Suture economy
- Disadvantages
- Less precise control of tension and approximation
- Failure may result in loss of entire suture line
Simple interrupted suture
simple cutnaneous suture
Ford Interlocking suture
Cruciate or Cross Mattress Suture
Figure-of-eight suture - like an upside down cruciate
Name six appositional suture patterns
- Simple interrupted
- Simple continuous
- Ford interlocking
- Cruciate or cross mattress
- Figure-of-eight
- Intradermal suture pattern (w/ perpendicular or parallel bites)
5 Tension relieving sutures
- Vertical Mattress
- Far-far-near-near
- Far-near-near-far
- Horizontal mattress
- Quilled and Stent
Vertical Mattress
Placed far from the wound incision - if you tie it tight enough, skin will evert
Far-far-near-near
far-near-near-far
Horizontal mattress
*blood supply is cut off with horizontal mattress - if suturing skin, vertical mattress is preferable
Quilled suture - not as common when we have ability to do walking sutures
When to use inverting suture patterns?
- closure of hollow viscera
- Imbrication (plication)
- NOT for use in skin b/c skin has natural tendency to already invert - dorsal surface of epithelium won’t heal together
Three inverting suture patterns:
- Lembert
- Halsted variation
- Cushing
- Connell
Lembert suture
- Different from vertical mattress - you go in and come out and go OVER the skin - needle stays in the same direction
Halsted Suture Pattern
Cushing
- Needle goes into the skin through the dermis, but does not go all the way to the lumen of that hollow organ
- DOES NOT GO INTO LUMEN!!!
Connell
- Same as cushing, but SUTURE GOES INTO THE LUMEN
Friction sutures are made for:
anchoring tubes
How to secure a tube with friction sutures
- Just one square knot
- Then surgeons throw (1/2 of surgeons knot) - tie off tube, and then you finish the surgeon knot.
- Square knot - tube - half of surgeons throw - finish surgeons throw
Securing a tube with friction sutures without using needle holders and forceps:
- Pass the suture through the needle
- Tie a square knot
- Insert the tube
- Place the tube onto the swuare knot and tie a surgeon’s knot
- Repeat the process for multiple friction sutures.
Hemostasis - sterile gauze application
Holding pressure with gauze - helps capillary bleeding.
DO NOT DAB!
Press with slight/moderate pressure and hold for a few seconds. Reapply if necessary.
Using Hemostatic Forceps
- Pay attention to the grooves inside the forceps
- Should be perpendicular to the suture
- End-on application
- Used for isolated blood vessels (grooves perpendicular to the vessel)
- Perpendicular application
- Used for blood vessels with pedicles (like ovarian pedicle during ovariohysterectomy - NOT for isolated vessels)
vet product of gelfoam is:
Vetspon - less expensive, almost identical
Electrosurgery:
- Electrodessication
- Electrocoagulation
- Electroincision
- Electrodessication - dessicating tumor surface
- Electrocoagulation - stops vessels from bleeding
- Electroincision - used during surgery, not used on skin because of dermal necrosis
Electrosurgery: monopolar vs bipolar
- Monopolar is MC
- foot panel to activate coagulation
- Bipolar
- Looks like a pair of forceps - creates a circuit when you pinch the tissue - neuro surgeons like this one because they feel like they have more control
Direct vs Coaptive Electrocoagulation
- Coaptive - apply to forceps
- Direct - apply directly to tissues - control excessive capillary hemorrhage
Electrocautery
- Electricity is used to ehat a metal element - no circuit like in electrocoagulation
- Then, that element is applied to the tissue
- No current passes through the tissue!!!!
Radiosurgery
- Ultra high-frequency radio waves pass from wire tip (active electrode) into the tissue to be cut or coagulated, depending on the waveform setting chosen, and on to a flat antenna (passive electrode)
- No need for conductive gel
- Patient not part of an electrical circuit
- Wire electrode remains cold
When does laser hemostasis not work?
Once you have blood in the field
Tissue and Vessel Fusion Benefits
- No dislodged clips
- Reduced lateral thermal spread, sticking, and charring
- No foreign material left behind
- Leaves tissue in its normal anatomical position
