How do you calculate how much fluid replacement a patient should get post-op?
(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.
How do you estimate the routine daily fluid requirements in a patient?
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.
Why might a normal patient get pulmonary edema and tachycardia ~3 days post-op?
3rd spaced fluid re-enters the intravascular space at this time and patients need their IV intake reduced to prevent complications.
Electrolyte content of gastric aspirate (NG fluids)
Na 100, K 10, Cl 140, HCO3 0
Electrolyte content of pancreatic juice
Na 140, K 5, Cl 75, HCO3 100
Electrolyte content of bile
Na 140, K 5, Cl 100, HCO3 60
Electrolyte content of small bowel drainage
Na 110, K 5, Cl 105, HCO3 30
Electrolyte content of distal ileum and cecum
Na 140, K 5, Cl 70, HCO3 50
Electrolyte conent of colon
Na 60, K 70, Cl 15, HCO3 30
Electrolyte content of D5W and D10W
Glucose 50mg/dL and 100mg/dL respectively
Electrolyte content of 0.9 NS and 0.45 NS
0.9 NS = 154mEq/L Na and 154mEq/L Cl. 0.45 NS = 77mEq/L Na and 77mEq/L Cl.
Normal urine output
Possible causes of acute diuresis in a patient
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.
Work up for a patient with massive diuresis
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.
Next step if your patient puts out 10mL urine per hour over 4 hours.
This is oliguria, most commonly due to dehydration. Check to make sure the Foley is draining appropriately and attempt volume resuscitation.
Next step if volume resuscitation does not increase urine output in an oliguric patient
CVP line or pulmonary artery catheter to assess the volume status. You can also check FeNa (
Next step if your patient develops hematuria after draining 1000mL from the bladder
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.
Next step if urine output drops after a small bout of hematuria.
Irrigate the bladder to dislodge any clots
Pre-renal oliguria labs
Urine osmolality > 500 mOsm/kg. Urine [Na] 20.
Post-renal oliguria loabs
Urine osmolality 250-300 mOsm/kg. Urine [Na] > 40mEq/L. FeNa > 3%. BUN:Cr
5 W's for post-op fever
Wind (atelectasis, pneumonia), Water (UTI), Walking (DVT/PE, catheter infxn), Wound infection, Wonder drugs (abx)
Most common cause of post-op fever in the immediate post-op period? Physical exam finding? Dx? Tx?
Atelectasis, bilateral fine pulmonary crackles on physical exam. Dx w/CXR simultaneously r/o pneumonia. Tx w/pulmonary toilet and incentive spirometry.
Second most common cause of post-op fever. How do you work it up? How do you treat?
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.
Tx for fluctuance beneath surgical incision
Open, drain, irrigate, wet/dry packings bid.
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?
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.
Possible causes of enteric contents leaking from prior incision site. How do you work this up/treat?
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.
What fistulas do not heal on their own?
"FRIEND". Foreign bodies. Radiation damage. Infection/IBD. Epithelialization of fistula. Neoplasm. Distal bowel obstruction.
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?
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.
Why can clostridium cause hemolysis in patients with gas gangrene?
The bacteria produces hemagglutinin and hemolysin toxins
Next step if your post-op patient who is a smoker complains of SOB and yellow sputum the next morning.
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.