Abx, Steroids, & Antiemetics

Question 1

Risk Factors for SSI

Answer 1

DM
Smoking
Hypothermia 
Preoperative shaving
Skin antisepsis
Antimicrobial prophylaxis
Inadequate sterilization of instruments 
Surgical technique

Question 2

Redosing Time of Ampicillin and Cefazolin

Answer 2

Depends on the abs half life A: 2 hrs C: 4hrs

Question 3

Redosing Considerations

Answer 3

Normal renal function: creatine clearance is 100 ml/min
- If < 60 ml/min consider adjusted dosing

Blood loss > 1.5L redone Vance half dose, redone all others full dose

Post-op redose limit to 24 hrs

Question 4

Clean Wound Organism & Abx & Allergy Abx

Answer 4

staphylococcus aureus & coagulase negative staphylococci
Cefazolin
beta lacatam allergy –> clindamycin or vancomycin

Question 5

Contaminated Wound Organism, Abx, & Allergy Abx

Answer 5

staphylococcus aureus & streptococci
Cefazolin & metronidazole
beta lactam allergy –> clindamycin

Question 6

Contaminated Oral Organism, Abx, & Allergy Abx

Answer 6

non-bacteroides fragilis, peptostreptococcus & prevotella
Ampicillin/sulbactam
Beta lactam allergy –> clindamycin

Question 7

Biliary & GI Wound Organism, Abx, & Allergy Abx

Answer 7

staphylococcus aureus & anaerobic gram – rods
Cefazolin & metronidazole
Beta lactam allergy –> clindamycin + aminoglycoside or fluoroquinolone

Question 8

Cefazolin

Answer 8

1st gen cephalosporin
o	MOA: beta lactam antimicrobial. Binds to the PBP (pcn-binding proteins) – inhibition of bacterial cell wall synthesis. Bacteriocidal. 
Dosing: 
- 2g for healthy adults 
- 3g > 120kg
- 25 mg/kg < 40 kg
- IV push over 3-5 min

Question 9

Vancomycin

Answer 9

broad spectrum abx
o MOA: Inhibits bacterial cell wall synthesis via inhibition of polymerization of peptidoglycans
- Often for pts with MRSA
Dosing:
- 1g over 1 hr
at least 50% should be infused before procedure

Question 10

Admin time of Abx

Answer 10

Cephalosporins up to 2 min before incision

Vanco & Flagyl 60 min before

Question 11

Beta Lactam Abxs & Risks

Answer 11

PCNs, cephalosporins, ampicillin

Risk: Allergic reaction

Question 12

Aminoglycosides

Answer 12

Gentamycin & Streptomycin

Risk: ototoxicity, nephrotoxicity, skeletal muscle weakness

Question 13

Tetracyclines

Answer 13

Doxycycline

Risk: Hepatotoxicity, Nephrotoxicity

Question 14

Fluoroquinolones

Answer 14

Ciprofloxacin, Levofloxacin

Risk: GI intolerance

Question 15

Macrolides

Answer 15

Erythromycin

Risk: P450 inhibition

Question 16

Vancomycin Infusion

Answer 16

Hypotension with rapid infusion
Red man syndrome
Steven Johnson Syndrome

Question 17

Gluccocorticoids

Answer 17

Released from adrenal gland.

Potent inhibitors of inflammatory mediators & up-regulate anti-inflammatory mediators. Depress immune system.

Question 18

Chronic Steroid Therapy Complication

Answer 18

suppression of hypothalamic-pituitary-adrenal axis (HPA)
Hypothalamus: cortico-releasing hormone
anterior pituitary: adrenocorticotropic hormone
adrenal cortex: cortisol
- Assume suppression if they take > 20mg/day of prednisone (or equivalent) for > 3 weeks
(16 mg/day of methylprednisolone, 2 mg/day of dexamethasone, or 80 mg/day of hydrocortisone)

• Body stops normal activation & release of hormones during stress because it has been used to receiving exogenous steroids

Question 19

Risk of Supra-physiologic Steroid Administration

Answer 19

• HPA suppression
• Impaired wound healing
• friability of skin, superficial blood vessels & other tissues
• risk of fx, infections, GI hemorrhage, ulcer

Question 20

Risk of Stress Dose Steroid

Answer 20

• Hyperglycemia
• HTN
• Fluid retention
• Increased risk of infection

Question 21

Steroid Requirement for Minor Surgery

Answer 21

no stress dose – take normal home dose

Question 22

Steroid Requirement for Moderate Surgery

Answer 22

take normal dose +
50 mg hydrocortisone IV prior to procedure
- Then 25 mg hydrocortisone q8hr for 24 hrs

Question 23

Steroid Requirement for Major Surgery

Answer 23

take normal dose +
100 mg IV hydrocortisone before induction
- 50mg q8hrs for 24 hrs
- Taper dose by half per day to maintenance level

Question 24

Steroid Choice

Answer 24

Consider glucocorticoid : mineralocorticoid ratio
- Hydrocortisone 1:1
- If > 100 mg – transition to Methylprednisone G > M
o Cortisol is influence by G

Question 25

Dexmethasone

Answer 25

synthetic glucocorticoid Use: PONV, edema/inflammation, post-op pain Dose: IV 4-12mg SE: delayed wound healing, HPA axis suppression, hyperglycemia DOA: up to 72 hrs All gluccocorticoid

Question 26

Risk Factors for PONV in adults

Answer 26

female nonsmoker hx of PONV/motion sickness post-op opioids

Question 27

Risk Factors for PONV in Pediatrics

Answer 27

surgery > 30 min, age > 3, strabismus surgery, hx of PONV

Question 28

Anesthesia related Risk Factors for PONV

Answer 28

Volatile anesthetics, duration of anesthesia, sugammadex

Question 29

Central pathway of PONV

Answer 29

stimulation of vestibular system --> central pattern generator (vomiting center) in medulla

Question 30

Peripheral pathway of PONV

Answer 30

irritation of GI tract --> nucleus tractus solitaries in brainstem --> area postrema at base of fourth ventricle in medulla (CTZ) --> central pattern generator (vomiting center)

Question 31

Neurotransmitters Involved in PONV

Answer 31

5HT3, D2, H1, M1, Neurokinin 1 via substance P

Question 32

Ondansteron

Answer 32

5HT3 receptor antagonist. Inhibits serotonin peripherally on vagus nerve & centrally in medulla’s CTZ • Dose: 4-8 mg • Use: PONV, chemo N/V • SE: HA, prolonged QT

Question 33

Phenothiazines

Answer 33

``` Promethazine (phenergen) o Antagonizes D2 (CTZ), H1, M1 o Use: PONV & motion sickness o Dose: 6.25-25mg IV o Caution in Parkinson’s & prolonged QT ```

Question 34

Butyrophenones

Answer 34

``` Droperidol o Use: PONV & sedation o Antagonizes D2 (CTZ) o Dose: 0.625 – 1.25 mg IV o Caution in Parkinson’s & prolonged QT ```

Question 35

Benzamines

Answer 35

Reglan o Use: antiemetic, decrease gastric volume, gastroparesis o Antagonizes D2 (CTZ) & enhances response to ACh in upper GI tract o Dose: 10 mg IV o Avoid in GI obstruction & Parkinson’s disease

Question 36

Diphenhydramine

Answer 36

H1 antagonist. o Use: hypersensitivities, anaphylaxis, motion sickness, antiemesis, & sedation o Antagonizes H1 receptors at effector cells in GI tract, BV, & resp tact o Dose: 10-50 mg IV o SE: somnolence, hypotension, dry mouth, thickening of bronchial secretions

Question 37

Scopolamine

Answer 37

``` o Use: transdermal o Antagonizes M1 receptors o Most effective admin the night before o Can cause sedation o Antisialagogue ```