fluids and electrolytes for surgeons
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Fluids and Electrolytes for surgeons. Anil S. Paramesh MD, FACS Associate Professor of Surgery and Urology. Why ?. Essential for surgeons (and all physicians) Knowledge can diagnose, treat and prevent many of the problems in surgical patients - PowerPoint PPT PresentationTRANSCRIPT
FLUIDS AND ELECTROLYTES FOR SURGEONS
Anil S. Paramesh MD, FACSAssociate Professor of Surgery and Urology
Why ? Essential for surgeons (and all physicians) Knowledge can diagnose, treat and prevent
many of the problems in surgical patients
Most abnormalities are relatively simple, and many
iatrogenic
Fluid Compartments
Total Body Water Relatively constant Depends upon fat content and varies with age
Men 60% (neonate 80%, 70 year old 45%) Women 50%
TOTAL BODY WATER60% BODY WEIGHT
ICF
2/3 (40% BW)Predominant solute
K+
ECF 1/3 (20% BW)
Predominant solute
Na+
H2O
75% interstitial25% intravascular (5% of BW)
It’s All About Balance
Gains and Losses Most individuals ingest approx 2 – 2.5 L/day Losses
Sensible and Insensible Typical adult, typical day
Skin 600 ml Lungs 400 ml Kidneys 1500 ml Feces 100 ml
Balance can be dramatically impacted by illness and medical care
How much fluid can a patient lose if a patient could lose fluid?
Sensible losses Blood (most pts can tolerate 500 cc BL) Sweat (up to 4 L /day) Tears – (diarrhea)
Insensible losses Skin 250 cc/day/degree fever Trach/vent – upto 1500 cc/day Peritoneum - > 1/day Third spacing
I LOVE SALT WATER!
(mEq/L) Plasma IntracellularNa 140 12K 4 150Ca 5 0.0000001Mg 2 7Cl 103 3HCO3 24 10Protein 16 40
Electrolytes
Fluid Movement
Is a continuous process Diffusion
Solutes move from high to low concentration Osmosis
Fluid moves from low to high solute concentration. Active Transport
Solutes kept in high concentration compartment Requires ATP
Movement of Water
Osmotic activity
Normal around 300 mOsm/L
Osmolality determined by concentration of solutes
Plasma (mOsm/L)
2 X Na + Glc + BUN 18 2.8
Fluid Status
Blood pressure Check for orthostatic changes Physical exam Invasive monitoring
Arterial line CVP PA catheter Foley
Volume Deficit Most common surgical disorder Signs and symptoms
CNS: sleepiness, apathy, reflexes, coma GI: anorexia, N/V, ileus CV: orthostatic hypotension, tachycardia with
peripheral pulses Skin: turgor Metabolic: temperature
HypovolemiaAcute Volume Depletion
Determine etiologyHemorrhage,
NG, fistulas, Aggressive diuretic therapy
Third space shifting, burns, crush injuries Ascites
What kind of fluid are we losing?
Sweat – hypotonic (low sodium) Insensible loss is pure water GI loss is usually isotonic
Stomach – acid, high CL Pancreas/bile – high HCO3 Saliva – high K
IV fluids a la carte
NaCl Normal saline (0.9%) has 154 mEq/L Na, 154
mEq Cl ½ Normal has 77 mEq Na/Cl
Lactated Ringers Has 130 Na, 109 Cl (also has some K, Ca,
lactate) D5Water
Good replacement for insensible losses
Case 1
6 month old boy, born full-term Developed worsening vomiting during the
past week Today he is listless, irritable, not tolerating
oral intake Pulse 145, BP 70/50 Diaper is dry, anterior fontanel depressed
Case 1 Labs
134 92 12
2.8 40 0.8
1545
20012.3
Case 1 F & E Problem List
Hypovolemia Hypochloremia Hypokalemia Alkalosis
134 92 12
2.8 40 0.8
Treatment – Patient weight is 12 kg
Fluid choice? Replace volume Replace K/Cl
How to order “Bolus”
Think about rate over time Adequate access important
What would maintenance fluid choice and rate be?
4-2-1 rule
Acid – Base Balance
Acidosis May result from decreased perfusion i.e. decreased
intravascular volume K will move out of cells (K+ - H+ exchange)
Alkalosis Complex physiologic response to more chronic
volume depletion i.e. vomiting, NG suction, pyloric stenosis, diuretics K will move intracellular
Paradoxical Aciduria
Na H
Na
K
Loop of Henle
HypochloremicHypovolemiaAldosterone activation
Case 1 When should we operate?
Need to wait until adequately resuscitated Why
Monitor by: Normalized vital signs Good urine output Normalized labs
Case 2
64 year old, 50 kg, had colon resection 5 days ago
“doing well” ….until…. Suddenly develops atrial fibrillation with rapid
ventricular response P 120, irregular; BP 115/70; RR 20 Temp 38.7 Confused, anxious
Case 2 Labs
128 100 12
3.0 22 0.8
8.928
18016.3
Mg 1.1
Case 2 Diagnoses?
New onset A fib, why?
Hypervolemia Hyponatremia Hypokalemia Hypomagnesemia Anemia
Case 2 Why does patient have hypervolemia?
Increased Antidiuretic Hormone (ADH)
Causes Surgical stress (physiologic) Cancers (pancreas, oat cell) CNS (trauma, stroke) Pulmonary (tumors, asthma, COPD) Medications
Anticonvulsants, antineoplastics, antipsychotics, sedatives (morphine)
Hyponatremia – how to classify Na loss
True loss of Na Dilutional (water excess) Inadequate Na intake
Classified by extracellular volume Hypovolemic (hyponatremia)
Diuretics, renal, NG, burns Isovolemic (hyponatremia)
Liver failure, heart failure, excessive hypotonic IVF
Hypervolemic (hyponatremia) Glucocorticoid deficiency, hypothyroidism
Patient was receiving maintenance fluids
D5 0.45NS at 125 ml/hr
Case 2 - How to treat
A fib: ACLS protocol Correct electrolytes
Replace Mg and K Decrease volume, fluid restriction
Case 3
23 year old with jejunostomy Had colon and ileum resected due to injury
Tolerates some oral nutrition, but has high output from jejunostomy (2.5 liters per day), therefore requires TPN
P 118, BP 105/60
Case 3 Labs
154 114 28
3.2 16 2.4
9.728
38010.3
Glucose 213Mg 1.4
Current Problems
Hypovolemia Increased plasma osmolarity
2 X 154 + (213/18) + (28/1.8) = 335 Hypernatremia Renal insufficiency Acidosis
Case 3 - Hypovolemia
Fistula output High volumes can rapidly lead to dehydration Electrolyte composition can be difficult to
estimate Can send aliquot to laboratory
May need to be replaced separately from maintenance (TPN) fluids
Hyperglycemia
Hypernatremia
Relatively too little H2O Free water loss (burns, fever, fistulas) Diabetes insipidus (head trauma, surgery,
infections, neoplasm) Dilute urine (Opposite of SIADH)
Osmotic diuresis Nephrogenic DI
Kidney cannot respond to ADH Too much Na, usually iatrogenic
Hypernatremia
[0.6 X wt (kg)] X [Serum Na/140 - 1]
Free water deficit:
Example:Na 154, 60 kg person
(0.6 X 60) X [(154/140) - 1]36 X [1.1 -1]36 X 0.1 = 3.6 Liters
Case 3 – How to Treat
Correct hyperglycemia Replace pre-existing volume deficits Reduce ostomy output if possible What to do with:
Acidosis? Hypokalemia?
154 114 28
3.2 16 2.4
Case 4
58 year old, had a recent kidney transplant Laboratory calls with critical value:
Potassium 5.9
What to do?
Case 4
Evaluate the patient Exam ECG Order repeat labs
Hyperkalemia - Common Causes
Hemolyzed specimen
Underlying disease Renal failure Rhabdomyolysis
Associated medications Too much K+, ACE inhibitors, beta-blockers,
antibiotics, chemotherapy, NSAIDS, spironolactone
Potassium and Ph
Normally 98% intracellular Acidosis
Extracellular H+ increases, H+ moves intracellular, forcing K+ extracellular
Alkalosis Intracellular H+ decreases, K+ moves into cells
(to keep intracellular fluid neutral)
Hyperkalemia - Treatment
Emergency (> 6 mEq/l) Monitor ECG, VS Calcium gluconate IV (arrhythmias) Insulin and glucose IV Kayexalate, Lasix + IVF, dialysis
Mild to Moderate Mild: dietary restriction, assess medications Moderate: Kayexalate Severe: dialysis