Postoperative Care

Question 1

How do you calculate how much fluid replacement a patient should get post-op?

Answer 1

(3ml NS per ml EBL) + other measureable losses (urine, drains or NG replace ml for ml w/fluid w/similar electrolyte concentration). Then subtract that from intraoperative fluids given. Also use your judgement to account for insensible losses like an open peritoneal cavity for an extended period of time.

Question 2

How do you estimate the routine daily fluid requirements in a patient?

Answer 2

1st 10kg = 100mL/kg/day. 2nd 10kg = 50mL/kg/day. Then 20mL/kg/day for every kg beyond 20kg. Using D5 0.5NaCl KCl 20mEq/L satisfies the normal Na, K and Cl daily requirements. LR or NS can be used in 1st 24 hours post op.

Question 3

Why might a normal patient get pulmonary edema and tachycardia ~3 days post-op?

Answer 3

3rd spaced fluid re-enters the intravascular space at this time and patients need their IV intake reduced to prevent complications.

Question 4

Electrolyte content of gastric aspirate (NG fluids)

Answer 4

Na 100, K 10, Cl 140, HCO3 0

Question 5

Electrolyte content of pancreatic juice

Answer 5

Na 140, K 5, Cl 75, HCO3 100

Question 6

Electrolyte content of bile

Answer 6

Na 140, K 5, Cl 100, HCO3 60

Question 7

Electrolyte content of small bowel drainage

Answer 7

Na 110, K 5, Cl 105, HCO3 30

Question 8

Electrolyte content of distal ileum and cecum

Answer 8

Na 140, K 5, Cl 70, HCO3 50

Question 9

Electrolyte conent of colon

Answer 9

Na 60, K 70, Cl 15, HCO3 30

Question 10

Electrolyte content of D5W and D10W

Answer 10

Glucose 50mg/dL and 100mg/dL respectively

Question 11

Electrolyte content of 0.9 NS and 0.45 NS

Answer 11

0.9 NS = 154mEq/L Na and 154mEq/L Cl. 0.45 NS = 77mEq/L Na and 77mEq/L Cl.

Question 12

Normal urine output

Answer 12

0.5-1 mL/kg/hr

Question 13

Possible causes of acute diuresis in a patient

Answer 13

Pre-existing renal disease w/inability to concentrate the urine, diabetes insipidus (lack of ADH or renal insensitivity to ADH). Post-obstructive diuresis can be caused by retained urea, Na and/or H20, typically in patients with chronic obstruction, edema, CHF, HTN, weight gain and azotemia.

Question 14

Work up for a patient with massive diuresis

Answer 14

If > 200mL over 2 hours, collect urine to further investigate the cause. If the urine has high osmolality, it is probably post-obstructive diuresis and will resolve in 1-2 days. If the urine has low osmolality, there is a pathologic concentrating defect and must be further investigated. Either way, keep the patient volume expanded until symptoms resolve or underlying cause is found.

Question 15

Next step if your patient puts out 10mL urine per hour over 4 hours.

Answer 15

This is oliguria, most commonly due to dehydration. Check to make sure the Foley is draining appropriately and attempt volume resuscitation.

Question 16

Next step if volume resuscitation does not increase urine output in an oliguric patient

Answer 16

CVP line or pulmonary artery catheter to assess the volume status. You can also check FeNa (

Question 17

Next step if your patient develops hematuria after draining 1000mL from the bladder

Answer 17

Hematuria is common after bladder overdistention. He should still have a urology consult to r/o malignancy, stones, infection, trauma and prostatitis. Cyclophosphamide can also cause hematuria.

Question 18

Next step if urine output drops after a small bout of hematuria.

Answer 18

Irrigate the bladder to dislodge any clots

Question 19

Pre-renal oliguria labs

Answer 19

Urine osmolality > 500 mOsm/kg. Urine [Na] 20.

Question 20

Post-renal oliguria loabs

Answer 20

Urine osmolality 250-300 mOsm/kg. Urine [Na] > 40mEq/L. FeNa > 3%. BUN:Cr

Question 21

5 W’s for post-op fever

Answer 21

Wind (atelectasis, pneumonia), Water (UTI), Walking (DVT/PE, catheter infxn), Wound infection, Wonder drugs (abx)

Question 22

Most common cause of post-op fever in the immediate post-op period? Physical exam finding? Dx? Tx?

Answer 22

Atelectasis, bilateral fine pulmonary crackles on physical exam. Dx w/CXR simultaneously r/o pneumonia. Tx w/pulmonary toilet and incentive spirometry.

Question 23

Second most common cause of post-op fever. How do you work it up? How do you treat?

Answer 23

UTI around day 3. R/o urinary retention w/bladder u/s or catherization. Get urine culture and treat with TMP-SMX or cipro po while waiting for culture results.

Question 24

Tx for fluctuance beneath surgical incision

Answer 24

Open, drain, irrigate, wet/dry packings bid.

Question 25

A patient presents with induration, edema and tenderness at his IV site. You change the IV site and notice a drop of pus at the old site. The patient has been spiking high fevers. How do you proceed?

Answer 25

This patient has suppurativ phlebitis (infected thrombus in the vein) and needs surgical excision of the infected vein, IV abx and wound healing by 3rd intention.

Question 26

Possible causes of enteric contents leaking from prior incision site. How do you work this up/treat?

Answer 26

Leak at ostomy site, anastomosis breakdown or missed enterotomy. If pt has peritonitis = operative exploration. If no peritonitis, get CT to r/o fluid collection. If +fluid collection, perc or operative drainage is indicated. If no fluid collection, manage non-operatively as enterocutaneous fistula (NPO, TPN, measure fistula output daily and monitor electrolytes) for several weeks. If fistulogram or small bowel series shows fistula persistence at 5-6 weeks and pt is free of infection, definitive repair should be scheduled.

Question 27

What fistulas do not heal on their own?

Answer 27

“FRIEND”. Foreign bodies. Radiation damage. Infection/IBD. Epithelialization of fistula. Neoplasm. Distal bowel obstruction.

Question 28

A patient presents after a blast injury, colectomy, ileostomy and mucous fistula with a fever of 105 during the night. Physical exam reveals erythematous edves, advangin brown skin discoloration and bleb formation w/foul odor and crepitus. How should you treat this patient?

Answer 28

He has gas gangrene/necrotizing fasciitis from a gas-forming organism like Clostridium perfringens. You should open the wound immediately and culture it. If + for clostridium perfringens (gm +, spore-forming rods), give high-dose PCN G and debride the wound. Hyperbaric oxygen may also help stop the infection and inhibit germination of spores.

Question 29

Why can clostridium cause hemolysis in patients with gas gangrene?

Answer 29

The bacteria produces hemagglutinin and hemolysin toxins

Question 30

Next step if your post-op patient who is a smoker complains of SOB and yellow sputum the next morning.

Answer 30

Smokers are at higher risk for bronchitis and pneumonia. Get CXR, ABG, CBC and sputum culture and gram stain. Start empiric abx if pt is febrile and suspicious CXR before culture results.

Question 31

Likely cause of hemoptysis in an inpatient if patient has had prior episodes? What if this was her first episode?

Answer 31

Prior = cancer. First = PE.

Question 32

Your patient becomes acutely hypotensive w/BP 80/60 and O2 sat of 85%. What should you do next?

Answer 32

Most imminent causes include MI and PE. 1st check his airway and intubate if necessary. Next get CXR and ECG. If MI, treat accordingly. If PE give IV heparin.