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Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents

Rapid Assessment and Correction of Sodium, Potassium, Calcium, and Acid-Base Disorders

39 quick-reference tables from the back of the book. Tick the ones you want, print, cut along the dashed lines, and slip them into a badge holder or phone case.

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Total body water fractions

Table A.1

Group	TBW fraction	At 70 kg
Adult man	0.6	42 L
Adult woman	0.5	35 L
Older man (65 or older)	0.5	35 L
Older woman (65 or older)	0.45	31.5 L

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.1. Check local policy before acting.

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Adult daily water and electrolyte requirements

Table A.2

Item	Requirement
Water	25 to 40 mL/kg
Sodium	1 to 2 mEq/kg
Potassium	About 1 mEq/kg (1 to 2 in parenteral nutrition)
Magnesium	8 to 20 mEq
Calcium	10 to 15 mEq
Phosphate	20 to 40 mmol

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.2. Check local policy before acting.

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Pitting edema grades

Table A.3

Grade	Depth	Recovery
1+	2 mm	Immediate
2+	4 mm	Under 15 s
3+	6 mm	Over 1 min
4+	8 mm	2-5 min

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.3. Check local policy before acting.

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IVC size and right atrial pressure

Table A.4

IVC	Collapse	RAP (mmHg)
2.1 cm or less	Over 50%	3 (0-5)
2.1 cm or less	Under 50%	8 (5-10)
Over 2.1 cm	Under 50%	15 (10-20)

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.4. Check local policy before acting.

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Adult BMP reference ranges and first question

Table A.5

Test	Adult reference	First question
Sodium	135-145 mEq/L	Glucose high? Lipids or protein high?
Potassium	3.5-5.0 mEq/L	Hemolyzed? ECG changes?
Chloride	98-106 mEq/L	Pair with bicarbonate for the anion gap
Bicarbonate	22-28 mEq/L	Low: acidosis. High: alkalosis or compensation
BUN	7-20 mg/dL	BUN:creatinine above 20: prerenal state, GI bleed, steroids
Creatinine	Baseline-dependent	Rise of 0.3 mg/dL in 48 h is AKI
Calcium	8.5-10.5 mg/dL	Albumin low? Check ionized if ill

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.5. Check local policy before acting.

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Typical lab critical values

Table A.6

Test	Act at once
Sodium	120 or below; 160 or above
Potassium	2.5-3.0 or below; 6.0 or above
Total calcium	6.0-6.5 or below; 13.0 or above
Ionized calcium	0.8 mmol/L (3.2 mg/dL) or below
Magnesium	1.0 mg/dL or below
Phosphate	1.0 mg/dL or below
Bicarbonate	10 mEq/L or below
Arterial pH	7.20-7.25 or below; 7.60 or above
Lactate	4-5 mmol/L or above

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.6. Check local policy before acting.

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Maintenance fluid rate (4-2-1 rule)

Table A.7

Weight band	Rate
First 10 kg	4 mL/kg/h
Next 10 kg (11-20)	2 mL/kg/h
Each kg above 20	1 mL/kg/h
Example: 70 kg	40 + 20 + 50 = 110 mL/h

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.7. Check local policy before acting.

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Daily maintenance requirements (adult)

Table A.8

Component	Per day
Water	25-30 mL/kg
Sodium	About 1 mEq/kg
Potassium	About 1 mEq/kg
Glucose	About 50-100 g

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.8. Check local policy before acting.

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Platelet transfusion thresholds

Table A.9

Situation	Transfuse if count below (/µL)
Prophylaxis, no bleeding	10,000
Central line (compressible site)	10,000
Lumbar puncture	20,000
Major non-neuraxial surgery	50,000
Nonoperative intracranial hemorrhage	No transfusion if count above 100,000 or on antiplatelet drugs

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.9. Check local policy before acting.

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Common IV fluid composition

Table A.10

Fluid	Na / Cl (mEq/L)	Other (mEq/L)	mOsm/L
0.9% saline	154 / 154	none	308
Lactated Ringer's	130 / 109	K 4, Ca 3, lactate 28	273
Plasma-Lyte A	140 / 98	K 5, Mg 3, acetate 27, gluconate 23	294
0.45% saline	77 / 77	none	154
D5W	0 / 0	glucose 50 g/L	252
D5 0.45% saline	77 / 77	glucose 50 g/L	406
3% saline	513 / 513	none	1,027
5% albumin	130-160 / varies	albumin 50 g/L	about 300

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.10. Check local policy before acting.

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Fluid responsiveness tests

Table A.11

Test	Positive if	Not valid when
Passive leg raise	Stroke volume or cardiac output rises 10% or more	Intra-abdominal hypertension; unreliable measurement
Mini-bolus 100-250 mL over 5-10 min	Stroke volume rises 10% or more	Cannot measure stroke volume
Pulse pressure variation	Above 12%	Spontaneous breathing, arrhythmia, low tidal volume
IVC variation	Collapse over 40% (weak)	Spontaneous breathing, right heart disease

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.11. Check local policy before acting.

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Vasopressor and inotrope quick table

Table A.12

Drug	Usual dose	Role	Note
Norepinephrine	0.05-0.5 mcg/kg/min (higher possible)	First-line pressor	Peripheral start acceptable
Vasopressin	0.03 units/min fixed	Add at norepinephrine 0.25-0.5 mcg/kg/min	Not titrated
Epinephrine	0.01-0.5 mcg/kg/min	Second-line; anaphylaxis	Raises lactate, tachyarrhythmia
Phenylephrine	0.5-3 mcg/kg/min	Pure alpha; tachyarrhythmia	Can lower cardiac output
Dopamine	5-20 mcg/kg/min	Select bradycardic patients	More arrhythmia
Dobutamine	2.5-20 mcg/kg/min	Low cardiac output inotrope	Can drop MAP
Angiotensin II	20 ng/kg/min; max 80 in first 3 h	Refractory vasodilatory shock	Thrombosis risk

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.12. Check local policy before acting.

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Volume depletion: clinical grading

Table A.13

Degree	Hemodynamics	Other findings
Mild	Normal supine and standing	Thirst, dry mucosa, concentrated urine
Moderate	Orthostatic HR or BP change	Low urine output, BUN:Cr over 20
Severe	Supine SBP under 90, HR over 100	Oliguria, confusion, lactate rise

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.13. Check local policy before acting.

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ATLS hemorrhage classes (70 kg adult)

Table A.14

Class	Loss	HR	BP
I	Under 15% (750 mL)	Normal	Normal
II	15-30% (to 1,500 mL)	100-120	Normal, narrow pulse pressure
III	31-40% (to 2,000 mL)	120-140	Normal or low
IV	Over 40% (over 2,000 mL)	Over 140	Low

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.14. Check local policy before acting.

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Hyponatremia correction limits

Table A.15

Source	Goal / 24 h	Limit
US expert panel	4-6 mEq/L in high-risk	8 mEq/L per 24 h
European 2014	Not specified	10 in first 24 h, then 8 per 24 h
High ODS risk	4-6 mEq/L	8 mEq/L in any 24 h
Practical target	6 mEq/L per 24 h	Stop hypertonic saline at 5 mEq/L or symptom relief

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.15. Check local policy before acting.

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Sodium monitoring schedule

Table A.16

Situation	Na check
Hypertonic saline bolus	After each bolus, then every 2-4 h
Continuous hypertonic infusion	Every 2-4 h
Tolvaptan	Frequently from the first dose; trials checked at 8 h and daily
Chronic, stable	Every 6-12 h, then daily (per local protocol)

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.16. Check local policy before acting.

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Total body water fractions for the free water deficit

Table A.17

Patient	TBW fraction	Example (70 kg)
Young man	0.6	42 L
Young woman or older man	0.5	35 L
Older woman	0.45	31.5 L

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.17. Check local policy before acting.

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Sodium content of fluids used in hypernatremia

Table A.18

Fluid	Na (mEq/L)	Free water %
D5W	0	100
0.2% NaCl in D5W	34	78
0.45% NaCl	77	50
Lactated Ringer	130	16
0.9% NaCl	154	0

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.18. Check local policy before acting.

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Hypercalcemia severity bands

Table A.19

Corrected Ca	Severity	Approach
<12 mg/dL	Mild	Treat cause; hydrate
12-14	Moderate	Saline; treat if symptomatic
>14	Severe	Saline + antiresorptive now

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.19. Check local policy before acting.

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IV calcium salts

Table A.20

Salt	Per 1 g (10 mL)	Line
Gluconate	90 mg elemental Ca (4.65 mEq)	Peripheral OK
Chloride	270 mg elemental Ca (13.6 mEq)	Central preferred

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.20. Check local policy before acting.

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IV magnesium sulfate repletion

Table A.21

Serum Mg (mg/dL)	MgSO4 IV	Over
1.5-1.9	2 g	2 h
1.0-1.4	4 g	4 h
Under 1.0	6 g	6 h
Torsades with pulse	1-2 g	5-60 min

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.21. Check local policy before acting.

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IV phosphate repletion

Table A.22

Phosphate (mg/dL)	Dose	Over
1.0-1.9	15-30 mmol	4-6 h
Under 1.0	30-45 mmol	6-8 h

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.22. Check local policy before acting.

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Expected compensation in simple acid-base disorders

Table A.23

Primary	Expected compensation	Limit
Metabolic acidosis	PaCO2 = 1.5 × HCO3 + 8 (± 2)	PaCO2 rarely under ~10
Metabolic alkalosis	PaCO2 rises 0.7 per 1 HCO3 rise (± 5)	Varies; hypoxemia limits
Acute resp. acidosis	HCO3 up 1 per 10 PaCO2 rise	HCO3 to ~30
Chronic resp. acidosis	HCO3 up ~3.5 (3-5) per 10 PaCO2 rise	HCO3 to ~42-45
Acute resp. alkalosis	HCO3 down 2 per 10 PaCO2 fall	HCO3 to ~18
Chronic resp. alkalosis	HCO3 down 4-5 per 10 PaCO2 fall	HCO3 to ~12-15

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.23. Check local policy before acting.

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Delta-delta ratio interpretation

Table A.24

Ratio	Reading
< 0.4	Non-gap acidosis
0.4-0.8	Gap plus non-gap acidosis
0.8-2.0	Gap acidosis alone
> 2.0	Gap acidosis plus metabolic alkalosis

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.24. Check local policy before acting.

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GOLDMARK causes of high anion gap acidosis

Table A.25

Letter	Cause	Clue
G	Glycols (ethylene, propylene)	Osmolar gap, crystals, AKI
O	5-Oxoproline	Chronic acetaminophen, malnutrition
L	L-lactate	Shock, hypoxia, metformin
D	D-lactate	Short bowel, normal lactate assay
M	Methanol	Visual loss, osmolar gap
A	Aspirin (salicylate)	Tinnitus, respiratory alkalosis
R	Renal failure	GFR below 15-20
K	Ketoacidosis	BHB, glucose, alcohol, fasting

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.25. Check local policy before acting.

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EXTRIP dialysis triggers for toxic acidosis

Table A.26

Toxin	Start dialysis	Stop
Methanol	Coma, seizure, vision loss, pH 7.15 or below, gap above 24, impaired kidney function, or methanol above 70 mg/dL (60 with ethanol, 50 without antidote)	Methanol below 20 mg/dL and improved
Ethylene glycol	Coma, seizure, AKI, gap above 27 (suggested at 23-27), or level above 310 mg/dL	Gap below 18 (or level below 25 mg/dL)
Salicylate	Level above 100 mg/dL (90 if impaired kidneys), altered mentation, hypoxemia, or failed standard therapy	Level below about 19 mg/dL and improved
Metformin	Lactate above 20, pH 7.0 or below, shock, or failed supportive care	Lactate below 3 and pH above 7.35

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.26. Check local policy before acting.

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Expected pCO2 in metabolic alkalosis

Table A.27

Serum HCO3 (mEq/L)	Expected pCO2 (mmHg, approximate)
30	44
34	47
38	50
42	53
46	55

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.27. Check local policy before acting.

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Urine chloride in metabolic alkalosis

Table A.28

Urine Cl (mEq/L)	Category	Typical causes
Below 20	Chloride-responsive	Vomiting, NG suction, remote diuretic, post-hypercapnia
20-40	Indeterminate	Repeat after volume status is clear
Above 40	Chloride-resistant	Aldosterone excess, Bartter or Gitelman, active diuretic, severe K depletion

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.28. Check local policy before acting.

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Expected compensation in acid-base disorders

Table A.29

Primary disorder	Expected compensation
Metabolic acidosis	PaCO2 = 1.5 x HCO3 + 8 (+/-2)
Metabolic alkalosis	PaCO2 rises 0.6-0.75 per 1 HCO3 rise
Acute respiratory acidosis	HCO3 up 1 (range 1-2) per 10 PaCO2 rise
Chronic respiratory acidosis	HCO3 up 3.5 per 10 PaCO2 rise
Acute respiratory alkalosis	HCO3 down 2 (range 1-2) per 10 PaCO2 fall
Chronic respiratory alkalosis	HCO3 down 4-5 per 10 PaCO2 fall

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.29. Check local policy before acting.

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DKA severity (BHB above 6 mmol/L also marks severe)

Table A.30

Severity	pH	HCO3 (mEq/L)	Mental status
Mild	7.25-<7.30	15-18	Alert
Moderate	7.00-7.25	10 to < 15	Alert or drowsy
Severe	< 7.00	< 10	Stupor or coma

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.30. Check local policy before acting.

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DKA vs HHS diagnostic criteria

Table A.31

Measure	DKA	HHS
Glucose	≥ 200 mg/dL	≥ 600 mg/dL
pH / HCO3	< 7.3 / < 18	≥ 7.3 / ≥ 15
BHB	≥ 3.0 mmol/L	< 3.0 mmol/L
Osm	variable	> 320 total

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.31. Check local policy before acting.

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Prerenal vs ATN urine indices

Table A.32

Test	Prerenal	ATN
Urine Na (mEq/L)	<20	> 40
FeNa	<1%	> 2%
FeUrea (on diuretics)	<35%	> 50%
Urine sediment	Bland, hyaline casts	Muddy brown casts
Urine osm (mOsm/kg)	> 500	~300

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.32. Check local policy before acting.

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Albumin dosing in cirrhosis

Table A.33

Indication	Albumin dose
Tap over 5 L	6-8 g per L removed
SBP with Cr >1, BUN >30, or bili >4	1.5 g/kg day 1, 1 g/kg day 3
HRS-AKI	1 g/kg day 1 (max 100 g), then 20-40 g/day

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.33. Check local policy before acting.

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Loop diuretic equivalent doses

Table A.34

Loop	IV (mg)	PO (mg)
Furosemide	20	40
Bumetanide	1	1
Torsemide	20	20

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.34. Check local policy before acting.

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IV potassium chloride rate limits

Table A.35

Line	Max rate	Max conc.
Peripheral	10 mEq/h	10 mEq/100 mL
Central, ECG	20 mEq/h	Per local protocol

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.35. Check local policy before acting.

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Hyperosmolar agents for raised ICP

Table A.36

Agent	Bolus	Hold when
Mannitol 20%	0.5 to 1 g/kg over 5 to 15 min	Trough osm gap above 20
3% saline	2.5 to 5 mL/kg (about 150 to 350 mL) over 5 to 20 min	Avoid sustained sodium above 160 mEq/L
23.4% saline	30 mL by central line over 10 to 20 min	Avoid sustained sodium above 160 mEq/L

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.36. Check local policy before acting.

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Parenteral nutrition daily electrolyte additions (adult)

Table A.37

Electrolyte	Adult daily range
Sodium	1 to 2 mEq/kg
Potassium	1 to 2 mEq/kg
Calcium	10 to 15 mEq
Magnesium	8 to 20 mEq
Phosphate	20 to 40 mmol

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.37. Check local policy before acting.

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Typical electrolyte replacement doses

Table A.38

Electrolyte	Trigger	Dose
Potassium	3.0-3.4	40-60 mEq PO, or 10 mEq/h IV
Potassium	Below 3.0	IV 10 mEq/h peripheral, plus oral
Magnesium	Below 2.0	2-4 g IV at 1 g/h
Phosphate	Below 1.0 or symptomatic	15-30 mmol IV over 6 h

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.38. Check local policy before acting.

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Peripheral vs central infusion limits

Table A.39

Agent	Peripheral	Central
Potassium chloride	10 mEq/h, 10 mEq/100 mL	Up to 20 mEq/h, ECG
Calcium	Gluconate 1-3 g over 5-10 min	Chloride preferred
3% saline	100 mL bolus over 10 min	Same; infuse via large vein if possible
Magnesium	1 g/h typical	Same

Fluids, Electrolytes, and Acid-Base Bedside Guide for Residents. Table A.39. Check local policy before acting.

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Educational study aid, not clinical advice. Always follow your facility's protocols, the orders of the responsible provider, and current drug labeling. Ranges and doses must be checked against your local references.