Antibiotics, Steroids & Antiemetics Flashcards
Risk Factors for Surgical Site Infections
Diabetes
Smoking
Colonization with microorganisms
Hypothermia
Skin antisepsis
Pre-op shaving
inadequate sterilization of instruments
surgical technique
When are periop antibiotics administered? What is the goal?
ATB are administered 1 hour before incision
Goal is for ATBs to be present at the skin during incision
______ can be pushed IV and quickly distribute to the skin.
Cephalosporins
_____ require longer infusion times (60 minutes)
Vancomycin and metronidazole
Should initiate infusion administration preoperatively
Redosing of the antibiotics depends on ____
the ATB’s half-life, the patient’s renal function and blood loss during the case
Half life of ampicillin
2 hours
Half life of cefazolin
4 hours
Concerning if creatinine clearance is ___
< 60 ml/min
Gentamycin and vancomycin have ____.
a narrower therapeutic index than cephalosporins
Redose antibiotic if estimated blood loss is ___.
more than 1.5 L
Vancomycin: half-dose
Other cephalosporins: full dose
Postop redosing should be limited to less than 24 hours
Clean skin wounds are at increase risk for ____.
staphylococcus aureus and coagulase negative staphylococci infections
thus, cefazolin is recommended, and if a severe beta-lactum allergy (hives, anaphylaxis), clindamycin or vancomycin
Contaminated skin wounds are at increase risk for ____.
staphylococcus aureus and streptococci infections
thus, cefazolin and metronidazole is recommended, and if a severe beta-lactum allergy (hives, anaphylaxis) clindamycin
Contaminated oral wounds are at increase risk for ___.
non-bacteroides fragilis, peptostreptococcus, and prevotella infections
thus ampicillin/sulbactam is recommended, and if a severe beta-lactum allergy (hives, anaphylaxis) clindamycin
Biliary/GI wounds are at increase risk for ____.
staphylococcus aureus and anaerobic, gram negative rod infections
thus, cefazolin and metronidazole is recommended, and if a severe beta-lactum allergy (hives, anaphylaxis) clindamycin and an aminoglycoside or fluoroquinolone
Patients Presenting for procedures already on ATB
Consider how long your patient has been on antibiotics, their last dose, when their next dose is due, and whether their current ATB regiment offers appropriate coverage for the scheduled procedure.
Do not hesitate to reach to collaborate with your department’s pharmacists for a consult.
Cefazolin
First generation cephalosporin
Wide therapeutic window
Inhibits bacterial cell wall synthesis
Dosing for Cefazolin
2g for most healthy adults
3 g for patients greater than 120 kg
25 mg/kg for patients less than 40 kg
Inject direct IV over 3 to 5 minutes
Penicillin allergy
10% of patients report a pcn allergy
90% of these patients are able to tolerate pcns
A 0.1% reaction rate is reported among pts with pcn allergy history (without pcn skin test) receiving cephalosportins
Vancomycin
Broad spectrum antibiotic
MOA: Inhibits cell wall synthesis
Often administered to patients with MRSA
Dosing for Vancomycin
1g administered over an hour, completed prior to incision
Examples of Beta-Lactams
Risks?
Penicillin, cephalosporins, ampicillin
Risk for Allergic reaction
Example of Aminoglycosides
Risks?
Gentamycin, streptomycin
Risk for ototoxicity, nephrotoxicity & skeletal muscle weakness
Example of Tetracyclines
Risks?
Doxycycline
Risk for Hepatoxicity & Nephrotoxicity
Example of Fluoroquinolones
Risks?
Ciprofloxacin, Levofloxacin
Risk for GI intolerance
Example of Macrolides
Risks?
Erythromycin
Risk for P450 inhibition
Risk for Clindamycin
Skeletal muscle weakness
Risks for Vancomycin
Hypotension with rapid infusion
Red man syndrome
Steven Johnson Syndrome
Risks for Metronidazole
Peripheral neuropathy
Effect of glucocorticoids on lungs and CNS
Lung maturation
CNS: anxiety, memory
Effect of glucocorticoids on heart and adipose tissue
CV: Hypertension
Adipose Tissue: obesity, lipolysis
Effect of glucocorticoids on skeletal muscle and bone
Skeletal muscle: myopathy
Bone: Osteoporosis
Effect of glucocorticoids on liver and immune cells
liver: lipid and glucose homeostasis
Immune cells: antiinflammatory & immunomodulation
Chronic glucocorticoid therapy can ____.
suppress the hypothalamic-pituitary-adrenal (HPA) axis and, during times of stress such as surgery, the adrenal glands may not respond appropriately.
The use of stress doses of glucocorticoids has become __
a common perioperative practice for patients on glucocorticoid therapy, based upon early case reports of intraoperative adrenal crisis after abrupt withdrawal of glucocorticoids
However, several studies suggest that supplemental exogenous stress glucocorticoids may not be needed to meet the demands of perioperative stress
Adverse effects of chronic glucocorticoid therapy
● HPA axis suppression
●Impaired wound healing
●Increased friability of skin, superficial blood vessels, and other tissues (eg, mild pressure may cause hematoma or skin ulceration, removing adhesive tape may tear the skin, and sutures may tear the gut wall)
●Increased risk of fracture, infections, gastrointestinal hemorrhage, or ulcer
What are some acute side effects of perioperative glucocorticoids?
●Hyperglycemia
●Hypertension
●Fluid retention
●Increased risk of infection
For these reasons, it is important to avoid givng them unless absolutely necessary.
The current approach is to determine perioperative glucocorticoid coverage based upon ___
1) the patient’s history of glucocorticoid intake
2) the type and duration of surgery planned
Patients who should be assumed to have functional suppression of hypothalamic-pituitary-adrenal (HPA) function include ____.
Any patient who is currently taking more than 20 mg/day of prednisone or its equivalent (eg, 16 mg/day of methylprednisolone, 2 mg/day of dexamethasone, or 80 mg/day of hydrocortisone) for more than three weeks.
Steroid consideration for minor procedures or surgery under local anesthesia
(eg, inguinal hernia repair), take usual morning steroid dose. No extra supplementation is necessary.
Steroid reccomendations for moderate surgical stress
(eg, lower extremity revascularization, total joint replacement)
take usual morning steroid dose. Give 50 mg hydrocortisone intravenously just before the procedure and 25 mg of hydrocortisone every eight hours for 24 hours. Resume usual dose thereafter.
Steroid recommendations for major surgical stress
(eg, esophagogastrectomy, total proctocolectomy, open heart surgery)
take usual morning steroid dose. Give 100 mg of intravenous hydrocortisone before induction of anesthesia and 50 mg every eight hours for 24 hours. Taper dose by half per day to maintenance level.
When selecting a drug to use as a perioperative stress dose, it is important to remember ___.
that in secondary adrenal insufficiency, the problem is a glucocorticoid deficiency (as opposed to a mineralocorticoid deficiency); therefore, the relative glucocorticoid and mineralocorticoid activity of the chosen drug must be taken into consideration.
Class and use of Dexamethasone
Synthetic glucocorticoid steroid
Uses include decreasing risk for PONV, edema (e.g. airway, cerebral), postoperative pain
Dosing and DOA of Dexamethasone
4 – 12 mg IV
Duration of action can be up to 72 hours
Side effects of Dexamethasone
delayed wound healing, HPA axis suppression, and hyperglycemia
Risk score for PONV in adults
- Female gender
- Nonsmoker
- History of PONV or motion sickness
- Post-operative opioids
When 0, 1, 2, 3, and 4 of the risk factors are present, the corresponding risk for PONV is about 10%, 20%, 40%, 60%, and 80%, respectively.
Risk score for PONV in pediatrics
- Surgery greater than 30 minutes
- Age greater than 3
- Strabismus surgery
- History of PONV or motion sickness
When 0, 1, 2, 3, or 4 of the depicted independent predictors are present, the corresponding risk for PONV is approximately 10%, 10%, 30%, 50%, or 70%, respectively.
What are some anesthetic risk factors for PONV?
Volatile Anesthetics
Duration of anesthesia
Sugammadex (limited research)
What five neurotransmitter receptor sites are of primary importance in the vomiting reflex?
- 5-hydroxytryptamine (HT)-3 – serotonin
- D2 – dopamine
- H1 – histamine
- M1 – muscarinic
- Neurokinin 1 (NK1) receptor – substance P
Example: D2 = receptor site and when dopamine (neutransmitter) binds to it that causes nausea/vomiting.
Describe the steps of Central stimulation for vomiting
vestibular system → central pattern generator (vomiting center) in medulla
Describe the steps of peripheral stimulation of vomiting
irritation of GI tract, overly full stomach → nucleus tractus solitaries in brainstem → area postrema (chemoreceptor trigger zone) at base of fourth ventricle in medulla → communicates with central pattern generator
Drugs or chemicals that can be triggering for nausea include
dopamine agonsts, cancer chemotherapy, apomorphine, digoxin
Some receptors for dopamine (D2) and serotonin (5-HT3) are found in ___ which contributes to nausea.
chemotrigger zone (CTZ) & emetic center (within the medulla)
Class & Use of Ondansetron
Class: 5-HT3 receptor antagonist
Used for PONV, chemotherapy N/V, carcinoid syndrome
Mechanism of Ondansetron
Inhibits serotonin both peripherally on vagus nerve terminals and centrally in the medulla’s CRTZ
Dosing of Ondansetron
4 – 8 mg IV
Side Effects of Ondansetron
Side effects include headache, prolonged QT interval
Class and Use of Promethazine
Class: Phenothiazine
Used for PONV and motion sickness
Mechanism of Promethazine
D2 (CRTZ), H1, Muscarinic Antagonist
Dosing of Promethazine
6.25 – 25 mg IV
Caution use of Promethazine in patients with ___
Parkinson’s or prolonged QT
What are the three types of dopamine receptor antagonists?
- Phenothiazines
- Butyrophenones
- Benzamines
Class and Use of Droperidol
Class: Butyrophenone
Used for PONV and sedation
Mechanism of Droperidol
D2 Antagonist in the CRTZ
Dosing for Droperidol
0.625-1.25 mg IV
Caution use of Droperidol in patients with ___
Parkinson’s or prolonged QT (torsades de pointes)
Class and Use of Metoclopramide
Class: Benzamide
Used for antiemesis, decreases gastric volume, symptomatic GERD, gastroparesis
Mechanism of Metoclopramide
D2 antagoonist (CRTZ), enhances Ach resonse in upper GI tract
Dosing of Metoclopramide
10 mg IV
Acoid giving Metoclopramide to patients with __
GI obstruction and Parkinson’s disease
Class & Use of Diphenhydramine
Class: First generation H1 receptor antagonist
Used for hypersensitivities, anaphylaxis, motion sickness, antiemesis, & sedation
Mechanism of Diphenhydramine
Antagonizes H1-receptors at effector cells in the GI tract, blood vessels, and respiratory tract
Dosing of Diphenhydramine
10 – 50 mg IV
Side effects of Diphenhydramine
somnolence, hypotension, dry mouth, thickening of bronchial secretions
How does scopolamine work for nausea?
Antagonizing the muscarinic receptor site
Per the PONV algorithm, if prophylactic treatment has failed, use___
an antiemetic from a different class than the prophylactic drug
What does the PONV algorithm suggest about Droperidol and Haldoperidol?
Avoid Droperidol in children unless other therapy has already failed
Use Haldoperidol only in adults
The PONV suggests what about Scopolamine and Dexamethasone?
Do not re-administer either of these agents for nausea
Dexamethasone is most effective when given ___.
during induction
5-HT3 Antagonists target which receptor? Using which ligand?
Give examples
5-HT3 receptor
Ligand: serotonin
Examples: ondansetron, dolasetron
Neurokinin-1 Antagonists target which receptor? Using which ligand?
Give examples
NK-1
Ligand: Substance P
Aprepitant (PO)
Dopamine Antagonists target which receptor? Using which ligand?
Give examples
D2
Ligand: dopamine
Examples: Droperidol, Haloperidol, Metochlopramide, Prochlorperazine
Antihistamines target which receptor? Using which ligand?
Give examples
H1 and M1
Ligand: Histamine & Acetylcholine
Examples: Diphenhydramine, Hydroxyzine & Promethazine
Anticholinergics target which receptor? Using which ligand?
Give examples
M1
Ligand: Acetylcholine
Example: Scopolamine (transdermal)
Steroids target which receptor? Using which ligand?
Give examples
Intracellular steroid receptors
Ligand: steroid
Examples: Dexamethasone
Mechanism of Dantrolene
Acts directly on skeletal muscle by interfering with release of calcium ion from the sarcoplasmic reticulum; prevents or reduces the increase in myoplasmic calcium ion concentration that activates the acute catabolic processes associated with malignant hyperthermia
Dosing of Dantrolene
2.5 mg/kg, continuously repeat dose until symptoms subside or a cumulative dose of 10 mg/kg is reached
Side Effects of Dantrolene
Dantrolene has a potential for hepatotoxicity
