Day 6 in ICU: Saline, Sodium and a Separated Wound
Mr H is 71 years old, weighs 70 kg (admission weight 64 kg), and is on day 6 of intensive care after emergency laparotomy for perforated sigmoid diverticulitis. He is sedated but rousable, ventilated through a tracheostomy, and on noradrenaline 0.10 µg/kg/min. In the last 24 hours he received 3.2 L of isotonic saline, passed 1.1 L of urine, and drained 1.4 L from a nasogastric tube. The abdomen is soft but distended; the midline wound has a 4 cm area of separation with granulation tissue visible at its base and no purulent discharge. Bloods: sodium 130, potassium 3.2, chloride 114, bicarbonate 19, urea 14, creatinine 132 (baseline 84), albumin 22 g/L, lactate 1.6, CRP 180, white cells 15; haemoglobin 88 g/L.
1. Interpret the sodium, chloride, potassium and bicarbonate results, and write the fluid prescription you would give over the next 24 hours with your justification.
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Pattern recognition
- Chloride 114 exceeds sodium 130, with bicarbonate 19: a hyperchloraemic, normal-anion-gap metabolic acidosis. The anion gap is roughly 130 − (114 + 19) = −3, i.e. no unmeasured anion.
- Sodium is low by dilution, not by loss: he has gained 6 kg and is in positive balance (3.2 L in versus 2.5 L out).
- Potassium 3.2 reflects nasogastric losses, urinary losses and intracellular shift; magnesium has not been checked and hypomagnesaemia will make the potassium refractory.
Prescription
- Stop 0.9% saline entirely. Each litre adds chloride and worsens both the acidosis and renal cortical vasoconstriction.
- Maintenance with a balanced crystalloid (Hartmann's or Plasma-Lyte) at about 25–30 mL/kg/day, i.e. 1.75–2 L.
- Replace nasogastric loss millilitre for millilitre with the same balanced fluid, containing 20 mmol KCl per litre (about 28 mmol/day of potassium replacement).
- Target urine output ≥0.5 mL/kg/h; check magnesium and replace if low before pushing more potassium.
Reasoning He does not need bicarbonate; the acidosis will correct as chloride falls. He does not need more volume - the weight gain and dilutional sodium argue for a neutral or slightly negative balance once resuscitation is complete. Review the noradrenaline requirement each shift; if it is falling and the lactate is normal, the resuscitation phase is over.
2. The resident asks for 200 mL of 20% albumin and 2 units of fresh frozen plasma because the albumin is 22 g/L and the INR is 1.4. How do you respond, and what would you do instead?
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Albumin 22 g/L This is an acute-phase, capillary-leak and dilutional number, not a diagnosis. Albumin has a half-life of about 20 days and a single 40 g dose will not durably raise the level in a septic, catabolic patient; much of it leaks into the interstitium and may worsen oedema. There is no evidence that correcting hypoalbuminaemia to a numeric target improves wound healing, fistula closure or survival. Albumin has defined roles - large-volume paracentesis, spontaneous bacterial peritonitis, selected cirrhosis and refractory ascites - none of which applies here.
INR 1.4 An INR of 1.4 does not predict bleeding and is not a threshold for prophylactic plasma. Plasma is indicated for active bleeding with coagulopathy, or before an invasive procedure in a patient with a demonstrated factor deficit. Two units will raise factors by only 5–10% and burden him with 400–500 mL of volume, plus risks of TRALI and infection.
What to do instead
- Treat the driver: source control, appropriate antibiotics, drainage of any collection, and adequate protein-calorie nutrition (enteral where possible - roughly 1.2–1.5 g/kg/day protein).
- Check fibrinogen, platelets and calcium before any procedure; give vitamin K if there is any suggestion of deficiency.
- Reassess in 48 hours; a rising CRP with a falling albumin usually means an undrained source rather than a nutritional problem.
3. What has happened to the wound, what will you do at the bedside today, and what would make you take him to theatre? Should enteral feed be continued?
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Diagnosis Superficial wound dehiscence with healthy granulation and no purulence, in a patient with obesity, sepsis, hypoalbuminaemia and a midline laparotomy - a mechanical and nutritional failure of early collagen deposition rather than a deep infection. The key question is whether the fascial layer is intact.
Bedside management
- Look and gently palpate; do not probe the depths with a cotton swab, which risks introducing infection.
- If the fascia feels intact and there is no bulging, manage open: irrigate with saline, pack lightly with saline-moistened gauze, and plan healing by secondary intention or delayed closure once the patient is anabolic.
- Swab only if there is discharge; do not start antibiotics for colonisation.
Indications for theatre
- Fascial dehiscence: a bulging wound, or salmon-pink serosanguineous discharge, which signals an intact-peritoneum-but-broken-fascia and imminent evisceration.
- Evisceration, an infected or necrotic deep collection, or uncontrolled sepsis from the wound.
- Suspected necrotising infection: pain out of proportion, crepitus, rapid spread.
Feeding Continue enteral nutrition. A superficial, non-infected wound is not a contraindication, and the gut mucosa and wound both benefit. Hold feed only if there is ileus, high nasogastric output or a planned return to theatre.