Intro to Surgery Flashcards
Define elective surgery
Non-emergent surgery which is scheduled at least 24 hours in advance
Define emergent surgery
Surgery for a condition which is immediately life-threatening. This term implies that surgery must be performed within a few hours (time frame varies)
What are some examples of preparations that can greatly improve the outcome of a surgery?
Appropriate pre-op medications (i.e. abx) Cardiac optimization Pulmonary optimization Empty stomach Bowel preparation
How far in advance of surgical incision is administration of abx recommended?
1 hour
Why is it optimal for a patient to have an empty stomach prior to surgery?
Decreases the likelihood of aspiration PNA
Elevated intra-abdominal pressure and delayed gastric emptying increase the risk for what to occur?
Increase aspiration risk
What are some examples of conditions that elevate intra-abdominal pressure and thus decrease stomach emptying?
Morbid obesity and pregnancy
What are some examples of conditions that delay gastric emptying and thus decrease stomach emptying?
Gastroparesis, pregnancy, abd trauma
How long does it take for clear liquids to clear the stomach (the “minimum fasting period” should be…)
2 hours
How long does it take for breast milk to clear the stomach (the “minimum fasting period” should be…)
4 hours
How long does it take for infant formula to clear the stomach (the “minimum fasting period” should be…)
4 hours (<3 months), 6 hours (> 3 months)
How long does it take for nonhuman milk to clear the stomach (the “minimum fasting period” should be…)
6 hours
How long does it take for a light meal to clear the stomach (the “minimum fasting period” should be…)
6 hours
Why would a patient need a preoperative bowel prep?
Decreases abdominal contamination in the event of bowel entry
Total body water is distributed with about ____% intracellular and ____% found in extracellular spaces. The extracellular portion is ____% interstitial and ____% intravascular/plasma.
66%; 33%
75%; 25%
Plasma volume = ____(fraction), or about ____%, of TBW (total body water).
1/12; 8.3%
Intravascularly, in addition to plasma, there are also formed elements such as ___, ___, and ___
RBCs, WBCs, and platelets
TBV = ___% x Body Weight (kg)
7%
____ ____ is the fluid excreted by cells
Transcellular water
1 L water weighs ____ kg
1 kg
Why are we so concerned about surgical pt’s fluid and electrolyte imbalance?
They cannot eat/drink Anesthesia Postop fever Surgical/pre-surgical trauma Sepsis
Sepsis causes (vasodilation/vasoconstriction)
Vasodilation
Anesthesia (especially GETA) causes increased ___(organ system)____ insensible loss
Pulmonary
Postop fever will (decrease/increase) insensible losses
Increase
Surgical (or pre-surgical) trauma affects distribution of body fluid from ______ to _____ spaces
Vasculature to extracellular “third space” (intercellular space)
What are some possible mechanisms/pathways for insensible losses?
Evaporation, condensation, sweat, stool
During and after a surgery, a pt is going to be in need of a lot of “replacement”–what needs replacing?
Fluid replacement (maintenance, ongoing, and any pre-existing volume deficits) Electrolyte replacement (any pre-existing electrolyte deficits)
How much fluid is required when considering the first 0-10 kg of body weight? The next 10 kg? For all subsequent kg of body weight (>20kg)?
100 mL/kg/day
50 mL/kg/day
20 mL/kg/day
What would the appropriate daily maintenance volume be for a 70 kg man who is NPO after surgery? Distributed over 24 hours?
1st 10 kg x 100 ml = 1000ml
2nd 10 kg x 50 ml = 500ml
Next 50 kg x 20 ml = 1000ml
TOTAL = 2500 ml/d
Distributed over 24 hours:
105 ml/hour
As patients become heavier than optimal body weight, IVF rates require adjustment according for ____ and ____.
BMI and BSA (body surface area)
In patients with compromised pulmonary, cardiac or renal function, what should be done in regards to their fluid replacement?
Run them “dry” for a longer period of time, to minimize fluid overload (CHF, pulmonary edema, etc)
What is the best way to monitor fluid status in a pt?
Measure urine output
For maintenance, you should administer Na+ at ____ mEq/kg/day and K+ at _____ mEq/kg/day
Na+ = 1-2 mEq/kg/day K+ = 0.5 - 1 mEq/kg/day
Why should you always give K+ with care, in a slow infusion, never as a bolus?
It HURTS!
T/F Ca++, PO4–, Mg++ are often not required for short term electrolyte replacement
True
Na 130, K+ 4, Cl 109, Bicarb 28, Ca2+ 2.7 is the composition of what replacement fluid?
Lactated Ringers (LR)
Na 154, Cl 154 is the composition of what replacement fluid?
0.9% Normal Saline (NS)
D5 1/2 NS is the composition of what replacement fluid?
Dextrose
D5 1/2 NS is the composition of what replacement fluid?
Fluids with dextrose
In addition to insensible losses, what are other reasons that operative pts may lose fluids ongoing?
NG tube Evaporation via open incision Operative bleeding Third space losses Drains Fistulae Burns
When considering ongoing fluid loss, with NG tube placement, what is the content of the losses that you should be concerned about? (hint: think about gastric contents)
H+, K+ and Cl- loss
Patients that are persistently low-volume after a surgery may still be losing what type of fluid? What causes for this loss should you be considering?
Intravascular
Think: Postoperative bleed? Sepsis (volume diffusing into the interstitial space)?
As a PA, you should be able to recognize an acute volume loss in patients. In order to be the best PA possible, what changes should you be looking for? (hint: think vital sign changes, urine output)
Changes in vital signs: BP
HR, CVP (central venous pressure)
Decreased urine output (post-op foley very helpful)
T/F Tissue changes are often obvious when there is an acute volume loss
False, they are usually NOT obvious
What are signs of volume excess?
Weight gain, pulmonary edema, peripheral edema, and S3 gallop
Fluids that have entered the 3rd space will eventually re-enter the intravascular space around what post operative day? What will happen to the patient’s urine output when this mobilization occurs?
Post operative day 3 (POD3)
Urine output will increase greatly
Try to correct abnormalities over ____ hours– do not go too (slow/fast)
24 hours; do not go too fast!
For seriously ill pts and pts w/ tenuous lung/cardiac status, calculate over (shorter/longer) period and reassess (less/more) frequently. For large fluid deficits, correct over a (shorter/longer) period of time.
shorter; more; longer
Fever ( ____F) is (common/uncommon) after surgery
101.3 F
common
What is postoperative fever usually due to? Does it resolve spontaneously or with tx?
The inflammatory stimulus of surgery
Resolves spontaneously
Fevers can result when _____ are released, which can be due to ____ _____ and (does/does not) automatically signal infection
cytokines; tissue trauma; does not
Cytokines are produced by ____, ____, and ____ cells
Cytokines are produced by monocyte, macrophages, and endothelial cells
Fever-associated cytokines are _____, _____, ____, _____
IL-1, IL-6, TNF-alpha, IFN-gamma
Cytokines in the bloodstream act on the ______ endothelium. They stimulate the production of ____ and ____. _____ acts to raise the hypothalamic “set-point,” resulting in heat ____ and increased heat _____.
Hypothalmic
PGE2 and cAMP
cAMP
heat conservation and increased heat production
What is the “mechanical” cause of the “shaking chills” that come before or with a fever? What are these called?
Rigors are due to rapid, alternating muscle contractions which generate heat. This is the body’s response to an increased “set” temperature.
Patients who are given Cervidil, Prostin, and Prepidil, which are cervical softening agents sometimes to induce labor, are 100% ____. What does this mean for the patient?
PGE2; patients given these drugs may have a fever as a result
What are the 5 Ws of post op fever?
Wind Water Wound Walking Wonder-drug (or What did we do?)
If a pt has a fever on day 1 or 2 post operatively, what “W” is this associated with?
Wind
What are possible causes of a “wind” associated postop fever? What day(s) post operatively is “wind” associated with?
Atelectasis (early, day 1, most common), PNA (later)
POD 1-3
What are possible causes of a “water” associated postop fever? What day(s) post operatively is “water” associated with?
UTI, anastomotic leak
POD 3
What are possible causes of a “wound” associated postop fever? What day(s) post operatively is “wound” associated with?
Wound infection, abscess
POD 5
What are possible causes of a “walking” associated postop fever? What day(s) post operatively is “walking” associated with?
DVT / PE
POD 7
What are possible causes of a “wonder drug/what did we do” associated postop fever? What day(s) post operatively is “wonder drug/what did we do” associated with?
Many drugs/blood transfusions can cause fever; central lines can cause line sepsis
ANY TIME!
In general, early fever is not infectious with one critical exception…
Necrotizing fasciitis/soft tissue infection
T/F Most early post-op fever resolves w/o treatment
True
T/F Fevers occurring earlier are more likely infectious
False, LATER fevers are more likely infectious
Define atelectasis
A partial collapse of the alveoli, often due to hypo-inflation.
Atelectasis occurs in the (least/most) dependent parts of the lung in ___% of patients who are anesthetized.
most dependent; 90%
The partial collapse associated with atelectasis causes (a decrease/an increase) in lung compliance, making it (easier/tougher) to re-inflate the lung
This partial collapse causes a decrease in lung compliance, making it tougher to re-inflate the lung
What are some risk factors for developing post-operative atelectasis?
Painful abdominal or thoracic incision (decreases pulmonary excursion)
Smoking
Pulmonary Disease (i.e. asthma, Cystic Fibrosis)
Obesity
Respiratory muscle weakness
Atelectasis is not an infection, but increases risk of ____ and causes _____ on its own.
PNA; fever
What is appropriate prophylaxis and tx of atelectasis?
Incentive spirometry
To better differentiate between PNA and atelectasis, look for ____ production, elevated ____, and temperature curve that progresses (downward/upward).
sputum; WBC; upward
In at-risk individuals, check __(lab)___ and ___(imaging)___, and consider ___(Rx)___ earlier than in non-risk individuals.
CBC w/ diff
CXR
Abx
When looking at a pt’s CXR that you’re differentiating between atelectasis and PNA, what are you looking for?
A unilateral infiltrate is most likely pneumonia, atelectasis will usually be bilateral
When do drugs tend to cause post-op fevers?
Any time!
Why are UTIs more common in women?
Shorter urethra, closer proximity to anus
Why do UTIs occur post operatively?
Catheter use during surgery
Delays in bladder emptying due to anesthesia
Bladder manipulation during surgery
Risks of developing a UTI are increased by what factors? (Think: gender, age range, comorbidities, mobility status)
Female gender
Older age
Diabetes
Immobilization
How do you dx a pt with a UTI?
UA and culture
T/F You should treat a pt prior to culture results if UA is suspicious for UTI
True
What is it about surgery that increases risk of a DVT?
Patient immobility and vascular damage
What is Virchow’s Triad?
Stasis, Vessel Damage, and Hypercoagulability
In addition to the 5 Ws of postoperative fever, it is important to think about what can kill the pt if you miss the dx. Therefore, it is important to consider other lethal causes of immediate fever, such as ….
Necrotizing infection (can kill rapidly)
Malignant hyperthermia
Anastomotic leak
Allergic rxn (to abx) or transfusion
What are the two main culprits of a necrotizing infection? (think: organisms)
Clostridium perfringens, Group A beta-hemolytic streptococcus
How do you treat a necrotizing infection?
Resuscitation, Pen G, surgical debridement
How do you treat malignant hyperthermia?
Resuscitation, rapid cooling, IV dantrolene (excitation-contraction decoupler)
How do you treat an anastomotic leak?
Place a drain or return to OR
What are some signs that may indicate a pt is having an allergic reaction to abx or transfusion?
Look for hypotension, rash
How do you treat an allergic reaction to abx or transfusion?
Stop the offending agent
What two conditions can present with a fever, but are “rare birds”? Others?
PE and MI
Other rare birds: ventilator-associated PNA, aspiration PNA, nosocomial infection, EtOH withdrawal (day 3)
What are the top three causes of subacute/delayed fever (after ~5 days post-op)? Approximate percentages of each?
#1: Wound infection (40%) #2: UTI (29%) especially if indwelling Foley #3: Pneumonia (12%) if on vent or COPD
What are other infections to consider as causes of subacute/delayed fevers post-op? Rarer ones to consider?
C. difficile colitis
Line sepsis and bacteremia
Intra-abdominal abscess
Rarer: Sinusitis, Meningitis, Acalculous cholecystitis
If the pt is weeks out from an operation and develops a fever, what are two considerations? (hint: think cardiac and prosthetics)
Endocarditis
Infected prostheses
T/F A pt can catch the flu or other contagious illnesses following surgery
True, OBVIOUSLY, but this is important! If a pt develops a post op fever, they may just have the flu or some other illness–remember, common things are COMMON :)
If called for post-op fever, get to the bedside, get the nurse/flow sheet and order a ____ with ____
Obtain a history, and if the situation is worrisome, jump to the _____ format
CBC with vitals
AMPLE format
When called to a pts bedside for a post-op fever, perform a PE. Place the following options in the order in which you should preform them:
A. lung sounds, heart/abd/extremity exam
B. check the wound or surgical site
C. check IV sites, central line, Foley, tubes
#1 check the wound or surgical site #2 lung sounds, heart/abd/extremity exam #3 check IV sites, central line, Foley, tubes
What is the importance of using wet to dry dressings?
Gradual debridement of a wound
What type of wounds would negative pressure wound therapy (“wound vac”) be appropriate for?
Wounds with copious serous drainage
I got 99 problems and having 99 notecards in this section ain’t one…
Welcome to card #100, happy studying! ;)
