8. Surgery Flashcards
indications for surgical prophylaxis antibiotics
- Implants (joint or internal fixation)
- Prolonged surgery (>2 h)
- Trauma surgery
- Revisional surgery
- Immunocompromised patient
- Extensive dissection required
- Intra-operative contamination
- Endocarditis (SBE)
MC used antibiotics for surgical prophylaxis
- Ancef
- Clindamycin if PCN allergy
- Vancomycin if concerned about MRSA
pre-op orders needed for in-house patient
- NPO after midnight, except AM meds with sips of water
- Hold all AM hypoglycemics and cover with SSI (if patient with DM)
- Accu-Check on call to OR (if patient with DM)
- Begin ½NSS @ 60 mL/h at 0600 (D5W½NSS if patient with DM)
- Labs – CBC with diff, PT/PTT/INR, BMP
- Chest X-ray, EKG (if necessary)
- Consult medicine for medical clearance (if not already done)
- Anesthesia to see patient (if necessary)
indications for pre-op chest x-ray?
- >40 years of age
- smoker
- any history of cardiac or pulmonary disease
indications for pre-op EKG?
- >40 years of age
- any history of cardiac disease
MC timeframe for post-op myocardial infarction
Day 3
how long should elective surgery be DELAYED following an MI or CABG
6 months
how to calculate daily fluid input requirements?
- First 10 kg x 100 = 1000 mL/day
- Second 10 kg x 50 = 500 mL/day
- Remaining kg x 20 = ___ mL/day
- (e.g. 70 kg patient requires 1000 + 500 + 1000 = 2500 mL/day)
how to calculate IV fluid input rate
- “421 Rule” calculates IV mL/h
- First 10 kg x 4 = 40 mL/h
- Second10 kg x 20 = 20 mL/h
- Remaining kg x 1 = ___ mL/h
- (e.g. 70 kg patient requires 40 + 20 + 50 = 110 mL/h)
what other factors should be considered prior to surgery
- Is the patient on any insulin, anticoagulants, steroids, or anything else that might put them at risk
- *Note: any non-routine orders should be cleared with patient’s primary service
perioperative management for patients with diabetes
- NPO after midnight
- Start D5W½NSS in AM
- Accu-Check
- If insulin-controlled, hold regular insulin, give ½ NPH dose, and cover with sliding scale insulin (SSI)
- If oral-controlled, hold oral meds and cover with SSI
- If diet-controlled, cover with SSI
what should be obtained prior to surgery on a patient with:
rheumatoid arthritis
Cervical spine x-ray
Why? – Cervical joint destruction in rheumatoid arthritis may lead to vertebral instability. The incidence of cervical instability is 5–7% –> Sxs range from initial neck pain radiating to the occiput to painless sensory loss in the extremities and a slowly progressive quadraperesis. Sudden death may also occur.
effects of long-term, high-dose course of steroids
Long-term therapy suppresses adrenal function
- Risk of poor or delayed wound healing. Decreased inflammatory process.
- Risk of infection. Low WBC may mask infection.
periop management for patients on long-term, high-dose steroids
- Peri-op IV steroid supplementation
- Hydrocortisone 100 mg IV given the night before surgery, immediately prior to surgery, and then
- q8h until postoperative stress relieved
periop management for patients at risk for gout
- Begin colchicine 0.6 mg PO daily 3-5 days pre-op
- and continue 1 week post-op
periop management for patients with hypertension
- If the patient has been on long-term diuretics (e.g. HCTZ, Lasix), check for hypokalemia
- Avoid fluids high in sodium; may use ½NSS at low rate
when to discontinue med prior to surgery:
Aspirin
7 days preop
due to irreversible binding to platelets
when to discontinue med prior to surgery:
NSAIDs
3 days preop
due to reversible binding to platelets
when to discontinue med prior to surgery:
Heparin
8 hours preop
(monitor partial thromboplastin time (PTT)
when to discontinue med prior to surgery:
Coumadin
3-4 days preop
(monitor PT/INR)
*prothrombin time, international normalized ratio
INR for elective surgeries should be:
< 1.4
what should be done if INR is > 1.4?
- If necessary, transfuse Fresh Frozen Plasma (FFP)
- One unit of FFP will decrease INR by approximately 0.2
- Vitamin K can be given but is slow-acting
when should a patient with an INR > 1.4 be allowed to proceed with surgery?
- If the risk of not doing surgery outweighs the risk of excessive bleeding (i.e. if it is an emergency surgery and you have anesthesia’s approval)
- If the patient has PVD and the surgery is a simple debridement or amputation.
- Note: if the patient has PVD, make sure you have Vascular Surgery’s approval for surgery.
- In this case, it is acceptable for the patient to bleed a little extra.
if patient w/ a high INR undergoes surgery, what labs should be carefully monitored?
Hgb and Hct
hemoglobin and hematocrit
RBC transfusion indications
- If Hgb <8 or Hct<24, consider transfusing 1-2 units PRBC
- One unit of PRBC will increase Hct by approximately 3 percentage points
if patient is thrombocytopenic, what can be done
- Order a six-pack of platelets, which is a concentration of six pooled platelet units, and consult hematology
how are relaxed skin tension lines (RSTL) oriented
perpendicular to the long axis of the leg and foot
*also called Langer lines, Cleavage lines, Wrinkle lines and Skin tension lines
Source: https://musculoskeletalkey.com/plastic-and-reconstructive-surgery/

should a skin incision typically be made parallel or perpendicular to the RSTL?
parallel incisions will remain approximated and heal better,
while perpendicular incisions may gap apart due to increased transverse forces

define: anti-tension line
S-shaped or zig-zagged incision when exposure needed is not parallel to RSTL

what should the ratio of length to width be to close a lesion with minimal tension
3:1 length:width

how much lengthening can be achieved with a 60o Z-plasty
75% lengthening
- can be achieved with a 60% Z-plasty*
- source: https://www.aafp.org/afp/2003/0601/p2329.html*

how should the Z-plasty incisions be oriented to correct a skin contracture
The central arm of the “Z” should be parallel to the contracture
Notes: The scar is excised, and a z-plasty is created with the lateral arms being the same length as the central wound. The lateral arms are drawn 60 degrees to the original central wound. The flaps are transposed, lengthening the direction of the original central line. The new central arm aligns with the flexor crease. The added length of skin across the crease prevents reformation of a contracted scar.
source: https://www.aafp.org/afp/2003/0601/p2329.html

how should the skin incision be oriented to correct
a 5th digit adductovarus rotation
Distal medial to proximal lateral

order of wound graft closure
- Direct closure
- Graft
- Local flap
- Distant flap
stages of skin graft healing
- Plasmatic
- Inosculation of blood vessels
- Re-organization
- Re-innervation
what are Blair and Humby knives?
Knives for harvesting skin grafts

MC device for harvesting skin grafts
dermatome
*used with a mesher

MC complication: skin grafts
*seroma, hematome
how to prevent seroma/hematoma during skin grafting
mesh or pie-crust graft and apply compressive dressing
advantages of meshing skin grafts
- donor site heals spontaneously
- expands tissue - smaller graft can cover larger site
- allows drainage of hematoma/seroma through the graft
- can drape extremely well around irregular surfaces
- increases surface area for re-epithelialization
disadvantages of meshing skin grafts
- graft is very fragile/delicate and easily torn
- contraction of graft during healing
-
inferior cosmetic appearance after healing
- may appear abnormally pigmented
- heals by secondary intention
- graft is very fragile/delicate and easily torn
can you mesh a full-thickness skin graft?
NO,
meshing is only for partial thickness skin grafts
advantages of full-thickness skin graft
- Minimal contraction of graft
- Better appearance
disadvantages of full-thickness skin graft
- More difficult to take
- Must close donor site
advantages of using a muscle flap
it brings immediate increased blood supply to donor site
AO principles of internal fixation (2002)
- Anatomic articular reduction, adequate shaft reduction
- Stable/biologic fixation
- Preservation of blood supply
- Early ROM

steps to inserting a fully threaded screw
- Overdrill near cortex
- Underdrill through far cortex
- Countersink
- Measure
- Tap
- Screw
how much of a screw should pass the far cortex
1.5 threads

(one and one-half)
purpose of tapping a screw
creates a path for the screw heads
- Technique: 2 forward, 1 back
- Cuts the thread pattern of the screw –> to RELEASE BONE DEBRIS
- Always the same size as the thread diameter.
purpose of countersinking a screw
Crozer:
- prevents stress risers and soft tissue irritation
- provides even compression from screw head (land)
Surg Skills:
- Increases the surface contact area
- makes the screw head less prominent

describe mini fragment sets
- Screw sizes of 1.5, 2.0, 2.7
- all fully threaded, cortical screws
screwdriver handle is made of:
pressed linen
differences between cortical and cancellous screws
- Cortical has smaller pitch
- Cortical has smaller rake angle
- Cortical has smaller difference between thread diameter and core diameter

define: malleolar screw
- function: for fixation of medial malleolus
- characteristics
- partially threaded
- same thread profile and pitch as cortical screw
-
trephine self-cutting tip
- allows insertion w/o tapping, and in osteoporotic bone sometimes even without predrilling the cancellous bone
- however, designed as lag screw for medial mall fx, but due to large diameter & large screw head –> smaller cancellous bone screws are used instead

what screw has a fluted tip
self-tapping
sizes in Synthes modular hand screw system
- 1.0
- 1.3
- 1.5
- 2.0
- 2.4
- 2.7
cannulated screw sizes in Synthes set?
- 3.0
- 4.0
cannulated screw sizes in Smith & Nephew set?
- 4.0
- 5.5
- 6.5
- 7.0
steps for inserting a 4.0 cannulated screw
- Insert 1.3 mm guide pin to far cortex
- Measure
- Drill near cortex with 4.0 cannulated bit (optional)
- Drill far cortex with 2.7 cannulated bit (unnecessary for soft bone)
- Tap (unnecessary with self tapping screws)
- Countersink
- Screw
define: Herbert screw
- Headless screw – can be inserted through articular cartilage
- *Also called “compression screws”
- Characteristics:
- Threaded portion proximally and distally and smooth in between.
- Proximal portion has tighter pitch for compression.

define: Reese screw
- Headless – create compression through arthrodesis.
- Characteristics:
- Proximal threads run clockwise
- Distal threads run counterclockwise. Smooth in between.
what are the K wire sizes and widths in millimeters?

why is there a question about K-wires in a screw set section in Crozer?
K-wires can be used for the underdrill if the situation arises (e.g. underdrill bit is missing or it
fell on the floor)
- The 0.062 can be used for the 1.5 underdrill (for the 2.0 screw)
- The 0.045 can be used for the 1.1 underdrill (for the 1.5 screw)
Mnemonic: Young Boys Wear Green

sizes of Steinmann pins
Everyone from 5/64 to 12/64
*except for 11/64
define: Steinmann pin
- a metal rod for the internal fixation of fractures by transfixing bone for traction or fixation
- use: most commonly used to repair fractures of the long bones
- characteristics:
- thin metal rod
- medical-grade stainless steel is rust-free that does not cause damage to the bone

different types of plate fixation
- compression
- neutralization
- buttress (anti-glide)
- bridge
define: compression plating
- Provides axial compression of fracture
- Pre-bend plate
- Eccentric drilling of hole adjacent to fracture; remaining holes drilled centrally
- Place plate on tension side of bone

define: neutralization plating
- Protects against shear, bending, and torsional forces at the fracture site
- Interfragmental compression obtained by lag screws
- All holes drilled centrally
define: anti-glide plating
Neutralization plate placed on the posterior aspect of the fibula

define: bridge plating
- Maintains alignment of unstable fracture fragments
- No interfragmental compression

should a plate be placed on the TENSION or COMPRESSION side of the fracture?
TENSION side of the fracture
is the tension side of a metatarsal on the DORSAL or PLANTAR aspect
PLANTAR side of metatarsal is the tension side
define: locking plate
- Plate in which threaded screws are secured into threaded plate holes
- Does not rely on the bone for stability but rather forms a fixed-angle construct
- Good for osteoporotic, comminuted fractures, or revision surgeries
define: Hooke law
strain is proportional to stress for material under load
define: Young’s modulus
after a load is removed, the material will spring back to its original shape,
the resulting slope represents the stiffness of a material or the Young modulus

define: Keith needle
straight needle

common needle point configurations
- Taper point – for soft, easily penetrated tissue (subcutaneous tissue, fascia)
- Cutting – cutting edge on inner curve (skin)
- Reverse cutting – cutting edge on outer curve for tough, difficult to penetrate tissue

what is orthofix
Polyglycolic acid
(same as dexon)
how long for orthofix to lose strength/absorb
- Loses strength in 6-12 weeks
- Absorbed in 1-3 years
what is orthosorb
PDS
*polydiaxonone
(PDS=orthosorb)
how long before PDS to lose strength/absorb
- Loses strength in 4-6 weeks
- Absorbed in 3-6 months
two sutures that are least reactive to tissues
- Stainless steel (less reactive)
- Prolene
what is Vicryl
Polyglactin 910
(a copolymer of 90% glycolide and 10% lactide)
how is Vicryl broken down
hydrolysis
into CO2 and H2O
*broken down by the body over time by processes such as hydrolysis and enzymatic degradation
how long for Vicryl to lose strength/absorb
- Tensile strength
- 75% @ 2 weeks
- 50% @ 3 weeks
- 25% @ 4 weeks
- Absorbed completely in 10 weeks
can you use Vicryl with an infection
Avoid it if possible, since vicryl is too reactive
who first described arthroscopy
Takagi
- Professor Kenji Takagi (1888–1963) was a Japanese orthopedic surgeon, noted for being the first to carry out a successful arthroscopy of the knee; performed first cadaver operation in 1918
first podiatrists to describe podiatric use for arthroscopy
Heller & Vogler (1982)
- described ankle joint arthroscopy*
- Source: Heller AJ, Vogler HW: Ankle Joint Arthroscopy. J Foot Surg 21: 23-29. 1982*
different scope techniques
- Scanning – side to side, up and down
- Pistoning – in and out
- Rotation – 360°
ankle scope indications
- Synovitis
- Osteochondral lesion/fracture
- Soft tissue impingement
- Osteophytes
- Loose bodies
arthroscopy: other uses
- Endoscopic plantar fasciotomy (EPF) or endoscopic gastroc recession
- Ankle fusion
- Arthroscopy of STJ or 1st MPJ
MC complication following EPF
(endoscopic plantar fasciotomy)
Lateral column instability → calcaneal-cuboid joint pain
MC indication for Lapidus
hypermobile first ray
*Lapidus fuses the 1st met-medial cuneiform joint
order of the lateral release for a McBride
- extensor hood
- ADH tendon release
- fibular sesamoid ligament
- lateral collateral ligament
- flexor hallucis brevis
- fibular sesamoid excision (if performing)

what is the difference between the:
Vogler, Kalish, and Youngswick
- Vogler: offset V (apex at metaphyseal-diaphyseal joint)
- Kalish: long-arm Austin with angles of approximately 55o for screw fixation
- Youngswick: Austin with a slice taken dorsally to allow decompression and plantar flexion

procedures correcting PASA
(proximal articular surface angle)
- Reverdin
- Peabody
- Biangular austin
- DRATO
- Offset V w/ rotation
procedure correcting PASA
(proximal articular surface angle)
proximal Akin

complications: Keller

*resection arthroplasty of base of proximal phalanx at 1st MPJ
- diminished propulsion of digit
- loss of hallux purchase
- stress fracture of 2nd metatarsal

the capital fragment falls on the floor,
what do you do?
- Rinse with saline
- Bacitracin soak for 15 minutes
- Rinse with saline
- Bacitracin soak for 15 minutes
- Rinse with saline
- Document and inform patient
causes of white toe post-operatively
- arterial in nature, usually acute
- signs:
- pain, pale, paresthesia, pulselessness
treatments: white toe
- D/C ice and elevation
- loosen bandages
- place foot in dependent position
- rotate k-wire
- apply warm compresses proximally (e.g. under popliteal area)
- apply nitroglycerine paste proximally
- local nerve block proximally
- avoid nicotine
- consult vascular surgery
causes: blue toe
- poor arterial inflow - toe is cold and doesn’t blanch with pressure
- poor venous outflow - toe is warm and will blanch with pressure
tx for arterial insufficiency blue toe
treat like white toe
- D/C ice and elevation
- loosen bandages
- place foot in dependent position
- rotate k-wire
- apply warm compresses proximally
- apply nitroglycerine paste proximally
- local nerve block proximally
- avoid nicotine and caffeine
- thermostat controlled heat lamp, do not exceed 90o
- vasodilators
- consult vascular surgery
tx for sluggish venous outflow blue toe
- D/C ice (but continue elevation)
- loosen bandages
- avoid dependency
- do NOT attempt to increase vascular perfusion
- consult vascular surgery
describe the Keck & Kelly procedure
- use: Haglund deformity + cavus foot + high calcaneal inclination angle (CIA)
- procedure:
- remove wedge from posterior-superior aspect of calcaneus
- posterior-superior prominence is moved anteriorly

treatments for equinus
- stretching/ exercises/ PT
- night splints
- gastroc recession
- tendoachilles lengthening
gastroc recession procedures for equinus
- baker
- strayer
- vulpius
- mcglamry & fulp
tendoachilles lengthening procedures for equinus
- open/closed Z
- hauser
- white
- hoke
- sgarlato
- stewart
define: Murphy procedure
Achilles advancement for spastic equinus
name procedures for pes planus:
transverse plane correction
- Evans
- Kidner
- C-C distraction arthrodesis
name procedures for pes planus:
sagittal plane correction
- Cotton
- Young
- Lowman
- Hoke
- Miller
- Cobb
name procedures for pes planus:
frontal plane correction
- Koutsogiannis
- Dwyer
- Chambers
- Gleich
- Baker-Hill
- Lord
name procedures for pes cavus:
tendon procedures
- Jones
- Hibbs
- STATT
- PT
name procedures for pes cavus:
bone procedures
- Dorsiflexory osteotomy of 1st metatarsal
- Cole
- Japas
define
- A surgical procedure to limit joint mobility (i.e. MBA implant in sinus tarsi)
- Typically want 2-4° of STJ eversion with implant
Valenti procedure (STJ):
define
- STJ block using a polyethylene plug with screw threads.
- Allows 4-5° of STJ pronation.
first person to describe triple arthrodesis
Edwin W. Ryerson of Chicago in 1923
(Recall: originally removed blocks of subchondral bone and reapplying as wedges)
order of joint RESECTION in a triple arthrodesis
classically:
- Midtarsal joints (T-N, CCJ)
- Subtalar joint (T-C)
However, might start with STJ and move to TN, then CC
order of joint FIXATION in a triple arthrodesis
classically, the reverse of resection:
- Subtalar joint
- Midtarsal joints
types of fixation for a triple arthrodesis
- 6.5-7.0 mm interfragmental compression screws
- staples
- plates
FDA-approved total ankle implants:
two-component devices
- Agility
- Eclipse
- INBONE
- Salto Talaris
FDA-approved total ankle implants:
three-component devices
- STAR is the only FDA approved 3-component system
- (Not FDA-approved – Buechal-Pappas, TNK, HINTEGRA)
stages of bone healing:
primary bone healing
Primary healing – no motion and no callus formation
- Inflammation
- Induction
- Remodeling
stages of bone healing:
secondary bone healing
Secondary healing – micro-motion with callus formation
- Inflammation
- Induction
- Soft callus
- Hard callus
- Remodeling
factors that negatively affect bone healing
- *smoking
- antimetabolite or steroid therapy
- anemia
- osteoporosis
name the types of non-unions
hypertrophic
- elephant foot
- horse hoof
- oligotrophic
atrophic
- atrophic
- wedge
- comminuted
- torsion wedge
study to distinguish hypertrophic and atrophic non-unions
Bone scan –
- +positive for a hypertrophic and
- negative for an atrophic (avascular) non-union
pseudoarthrosis:
define
Type of non-union in which fibrocartilaginous tissue forms between fracture fragments
bone stimulator:
indications
- Non-union
- failed fusion
delayed union versus non-union
- Delayed union: between 4-6 months after injury without radiographic progression of healing or the instability of a fracture upon clinical examination
- Non-union: fracture that does not unite within 9–12 months
bone stimulators:
contraindications
- pseudoarthrosis
- gap greater than ½ bone diameter
avascular necrosis:
stages
- Avascular – loss of blood supply, epiphyseal growth ceases
- Revascularization – infiltration of new blood vessels, new bone deposited on dead bone, flattening or fragmentation of articular surface
- Repair and remodeling – bone deposition replaces bone resorption
- Residual deformity – restoration of epiphysis, sclerosis, deformed articular surface
best study to evaluate avascular necrosis
MRI –
- decreased signal intensity within medullary bone in both T1 and T2 images
different types of bone grafts
- OsteoGENIC – able to synthesize new bone
- OsteoINDUCTIVE – contains factors that induce host tissue to form new bone
- OsteoCONDUCTIVE – provides scaffold for host tissue to propagate new bone
osteogenic bone graft:
examples
Osteogenic – able to synthesize new bone
- Mesenchymal stem cells from autologous bone or bone marrow aspirate
osteoinductive** bone graft:
examples
Osteoinductive – contains factors that induce host tissue to form new bone
- Demineralized bone matrix
- Bone morphogenic protein
- Platelet-derived growth factors
osteoconductive** bone graft:
examples
Osteoconductive – provides scaffold for host tissue to propagate new bone
- Allografts
- Hydroxyapatite
- Calcium phosphate
- Calcium sulfate
what type of bone graft is osteogenic, osteoinductive, AND osteoconductive?
autograft
bone graft healing:
stages
- Vascular ingrowth
- Osteoblastic proliferation
- Osteoinduction
- Osteoconduction
- Graft remodeling
early radiographic finding of bone graft healing
Initial radiolucency of the graft due to increased osteoclastic activity, which is followed by osteoblasts laying down new bone
creeping substitution:
define
Process in which the host’s cutting cone (osteoclasts followed by osteoblasts) invade bone graft
ASA classification for general anesthesia
American Society of Anesthesiologists classification
- Class 1 – healthy
- Class 2 – mild systemic disease
- Class 3 – severe systemic disease
- Class 4 – incapacitating systemic disease that is a threat to life
- Class 5 – moribund patient who is not expected to live without surgery Emergency
maximum tourniquet time
90-120 minutes;
after that, allow 5 minutes of perfusion for every half hour over
tourniquet contraindications
- Infection
- Open fracture
- Sickle cell disease
- Peripheral vascular disease
- Recent arterial graft
- Previous DVT
- Hypercoagulability
- Skin grafts application where bleeding must be distinguished
Seddon classification:
nerve damage
- Neuropraxia – nerve contusion resulting in conduction block that recovers promptly
- Axonotmesis – interruption of axons with distal Wallerian degeneration. Supporting connective tissue sheaths remain intact allowing regeneration.
- Neurotmesis – complete severance of the nerve that is irreversible
neuropraxia:
define
nerve contusion resulting in conduction block that recovers promptly
Axonotmesis:
define
- interruption of axons with distal Wallerian degeneration.
- Supporting connective tissue sheaths remain intact allowing regeneration.
Neurotmesis:
define
complete severance of the nerve that is irreversible
difference between INCISIONAL and EXCISIONAL biopsy
- Incisional – only a portion of the lesion is removed
- Excisional – the entire lesion is removed
different biopsy techniques
(hint: 4)
- Punch
- Shave
- Curettage
- Surgical excision
bone stimulator:
how does it work
Piezoelectric principle
- side under compression makes a negative charge that leads to bone growth
- therefore, placing a cathode in a non-union site will stimulate growth
direction of the cut for reverse Wilson of the 5th metatarsal
Distal lateral to proximal medial
first to describe arthrodesis
(not a triple)
Robert E. Soule (1910)
first described arthrodesis of PIPJ for correction of hammertoe deformity (end-to-end arthrodesis)
order for hammertoe surgery
Note: Perform a Kelikian push-up test to determine if the next step is required
-
(1) PIPJ
- Tendon
- Dorsal capsule
- Collaterals
- Plantar capsule
- Arthroplasty
-
(2) MPJ
- Hood
- Tendon
- Capsule
- Plantar plate
-
(3) PIPJ
- Arthrodesis
joint implants:
purpose
Maintain space between bony surfaces
Relieve pain
lag time for osteomyelitis to show on x-ray
10-14 days
how to culture osteomyelitis
- Take one culture from the infected bone, and
- Take a second culture proximal to the clearance margin to ensure remaining bone is not infected
Brodie abscess:
define, treatment
- Subacute osteomyelitic lesion usually found in children; well-circumscribed, lytic lesion with sclerotic borders found in the metaphysis, epiphysis, and rarely diaphysis.
- Painful with periods of exacerbation and remission.
- Tx: curettage and packing with autologous bone
antibiotic beads:
define, and adjuvants
- PMMA or Poly(methyl methacrylate).
- Gentamycin or tobramycin are often used since they are heat stable with good diffusion coefficiencies.
- Vancomycin and cefazolin may also be used.