Fluids & Fluids & ElectrolytesElectrolytes

Scott G. Sagraves, MD, FACS Assistant Professor

Trauma & Surgical Critical Care

The recognition and management of fluid,

electrolyte, and related acid-base problems are

common challenges on the surgical service.

Lawrence, Essentials of General Surgery

Goals• Review concept of total body fluids

• Review types of crystalloids

• Review electrolytes disturbances & their treatment strategies.

Body Fluids

Intercellular

Intravascular

Interstitial40%

16%

4%

Body Water = 60% of a patient’s body weight

Why do you give D5½NS + 20 mEq/L KCl

at 125 cc/hr to a patient?

Fluid Requirements

• typically 35 mL/kg/day

• insensible loss = 700 mL/day or 0.2 cc/kg/day for every 1° C > 37°

• 1-10 kg = 100 mL/kg/day {4mL/kg/hr}

• 11-20 kg = 50 mL/kg/day {2mL/kg/hr}

• > 21 kg = 20 mL/kg/day {1mL/kg/hr}

Trick for hourly maintenance = 40 + weight (kg)

Serum Values of Electrolytes

Cations Concentration, mEq/L

Sodium 135 - 145

Potassium 3.5 - 4.5

Calcium 4.0 - 5.5

Magnesium 1.5 - 2.5

AnionsChloride 95 - 105

CO2 24 - 30

Phosphate 2.5 - 4.5

Daily Requirements for Electrolytes

• Sodium: 1-2 mEq/kg/d

• Potassium: 0.5-1 mEq/kg/d

• Calcium: 800 - 1200 mg/d

• Magnesium: 300 - 400 mg/d

• Phosphorus: 800 - 1200 mg/d

IV SolutionsSolutionNa+ Cl- K+ Ca+2 HCO3- Glu

Plasma 141 103 4-5 5 26 0

NS 154 154 0 0 0 0

D5W 0 0 0 0 0 50 G

LR 130 109 4 3 28 0

Serum Osmolality = [2 x Na] + [BUN/2.8] + [glucose/18]

Replacement Strategies

• Sweat: D5¼NS + 5 mEq KCl/L

• Gastric: D5½NS + 20 mEq KCl/L

• Biliary/pancreatic: LR

• Small Bowel: LR

• Colon: LR

• 3rd space losses: LR

Resuscitation• Crystalloids

• Replace blood loss at a 3:1 ratio

• Initial bolus 1-2 liters, usually normal saline

• If they have transient response, give additional fluids. Once 3-4 liters of crystalloid has been given consider blood.

INDICATORS OF SUCCESSFULRESUSCITATION

• PULSE 100 - 120 bpm• URINARY OUTPUT

– CHILDREN = 1.0 ml/kg/hr– ADULT = 0.5 ml/kg/hr

• Clearance of lactate• Resolution of base deficit

• BLOOD PRESSURE POOR INDICATOR

Fluid Status

[Na]

ECV

low normal high

160

140

120

140

GI loss

SIADHHypothyroid

Cortisol CHFCirrhosis

NaHCO3

3% NaClSeawater

DIInsensible

GI LossRenal lossOsmotic

Renal Regulatory Mechanisms

• Aldosterone– distal tubules– sodium exchanged for K+ and H+

– released by volume reduction

• Antidiuretic Hormone (ADH)– increased tubular water reabsorption– posterior pituitary release

Acid/base

7.4

BE = 0HCO3 = 24

RespiratoryAcidosis

MetabolicAcidosis

MetabolicAlkalosis

RespiratoryAlkalosis

ABG Rules• Rule 1: An increase or decrease in

PaCO2 of 10 mm Hg, respectively, is associated with a reciprocal decrease or increase of 0.08 pH units.

• Rule 2: An increase or decrease in [HCO3-] or 10 mEq/L respectively is associated with a directly related increase or decrease of 0.15 pH units.

Acidosis

• pH < 7.2– decreased responsiveness to catecholamines– cardiac dysfunction– arrhythmias– increased potassium serum levels

Case Studies

“Found Down”

• 45 yo WM, found down, presumed to be assaulted, well known to ED for EtOH

• CT head - hygromas, small ICH• labs:

– Na = 118– K = 2.4– Cl = 74

What do you think? What do you do?

Severe Hyponatremia

• Correct sodium to above 120 mEq/dl– NaCl + 40 mEq/L KCl– 3% Saline– furosemide diuresis (euvolemic)– serial electrolytes– be prepared to handle seizures

• Replace potassium• Cl should correct itself

Hyponatremia

• 1% of hospitalized are hyponatremic

• Neurologic conditions:– Seizures, coma, encephalopathy– Results from rapid [Na]

• Peripheral symptoms:– Cramping, twitches, fasciculations– Results from ion conduction aberrations

Hints…• Na+ deficit (mEq) =

(140 – Naserum) x 0.6 x Kg

• Glucose increase 100 mg/dL or a BUN increase of 30 mg/dL decrease of 1.5 – 2 mEq/L Sodium

Central Pontine Myelinosis

• Results from overcorrection of sodium

• Correction of > 25 mEq per 24-48 hrs

• Concurrent hypoxia

• Presence of liver disease

• Acute correction limit 25 mEq /day

• Chronic correction limit 10 mEq/day

Treatment Strategies• Hypovolemic Hyponatremia

– expand intravascular volume• 0.9% NS or 3% Hypertonic Saline

• Hypervolemic Hyponatremia– water restriction– treat medical condition– hemodialysis

• Euvolemic Hyponatremia– SIADH

• restrict fluid: 7-10 ml/kg/d• demeclocycline antagonizes vasopressin

HDU Code

A Code Blue is called in the HDU.

65 yo male with ESRD has “arrested” awaiting his dialysis treatment. CPR and BVM resuscitation are in progress and an

IV has been established.

What do you think? What do you do?

Pre-Arrest Rhythm Strip

“Arrest” Strip

Diagnosis?

HYPERKALEMIATreatment

CaCl2 10% - 1 ampule Sodium Bicarbonate - 1 ampule D50 & Insulin 10 U 2 - agonist nebulizer- cellular K Kayexalate®

Causes of Hyperkalemia

• Renal dysfunction• Acidemia• Hypoaldosteronism• Drugs• Excessive intake• WBC > 100,000• Platelets > 600,000

• Cell Death– Rhabdomyolysis– Tumor lysis– Burns– Hemolysis

Potassium Metabolism

• Normal daily intake 100 mEq

• Renal filters & reabsorbs prox. Tubule

• Potassium 1/[aldosterone]

• Acidosis [potassium] with H+ out

• Alkalosis [potassium] with H+ in

Post op patient• 42 year old female admitted to the ICU post

op after undergoing a thyroidectomy for thyroid cancer.

• She is complaining of peri-oral numbness and tingling. Her DTRs are hyperactive and her ECG has a prolonged QT interval.

What do you think? What do you do?

HYPOCALCEMIA

• Chvostek’s sign - facial muscle spasm

• Trousseau’s sign - carpal spasm

• Treatment– monitor ECG– IV calcium– follow up labs– oral calcium supplements

• normal is 1 gram/day

Blunt Trauma• 23 year old male, s/p MVC with blunt

abdominal and orthopedic trauma

• HD#3 develops fever, N/V, abdominal pain, refractory hypotension, with oliguria.

• Na+ 130, K- 5.5, Glu 65, pH 7.29

What do you think? What do you do?

ACUTE ADRENAL INSUFFICIENCY

• Treatment– fluid and vasopressor support– treat precipitating conditions– draw baseline cortisol level– administer dexamethasone– ACTH stimulation test– hydrocortisone 100 mg IV q 8

Hydrocortisone Stimulation Test

• Baseline cortisol– > 20 - no further therapy– 15 - 20 - test– < 15 empiric therapy

• Administer Cortrosyn 250 g IV

• Obtain levels 30 & 60 minutes post injection

You are called to the Bedside…

What Do You Think? What Do You Do?

• 55 yo male, s/p fall with isolated, repaired fractured femur.

• Pt’s LOC decreased and patient began to seize.

• EKG showed…

Hypomagnesemia

• Mg plays role in energy metabolism, protein synthesis, cell division, & calcium regulation in muscle.

• Definition < 1.6 mg/dL

• Causes: poor diet, diuretics, gut losses, & massive diarrhea, resuscitation.

Mg Rx• Replacement Magnesium Sulfate

– 1 gram = 8 mEq

– Infuse at rate of 2 gram/hour

– Emergency: 2 grams over 5 minutes

Closed Head Injury

• 32 year old female, MVC, GCS -7, intubated, with CT scan showing SAH, cerebral edema. ICP monitor shows a pressure of 27. CPP 55.

• Over the next several days, Na+ > 150.

What do you think? What do you do?

DIABETES INSIPIDUS• Signs

– [Na+] 150– Urine specific gravity 1.007– polyuria, clear urine – dDAVP 1g sq raises urine osmolality in 2 hours

• Treatment– free water deficit = (0.6) x (Kg) x ([Naserum/140] -1)

– dDAVP 2g sq every 12 hours– for every L water deficit [Na+] will rise 3 mEq

above 140

The transfer• 50 year old obese female, transferred for

critical care management after a bowel resection. Presents with obtundation, hypotension, tachypnea, and emesis.

• C/O abdominal pain and has fruity breath

• amylase, lipase are elevated, Na+ 127

What do you think? What do you do?

Work up?

• ABG

• Electrolyte panel

• urine analysis

• CBC

• Serum Ketones

HyperglycemiaCharacteristic DKA NKHC

Glucose 400-800 > 1000

Acidosis Severe min.

Ketones High low

Dehydration Mod. High

Na 1.6 for every 100 glucose above 200

Treatment• Adequate fluid replacement

– narrowing of anion gap– crystalloids: LR, NS, ½ NS

• Insulin– bolus 0.1 - 0.5 units/kg– infusion 0.1 units/kg/hour– goal reduce plasma glucose 75-100 mg/dL/hr

• Electrolytes– K replacement 10-20 mEq/hour after UOP OK

– Mg, PO4 replacement

The drunk• 37 year old male, h/o EtOH abuse fell from a

deer hunting tree stand. C5 fracture without cord involvement.

• HD #2 develops delirium tremors moved from SIU to ICU. Librium started.

• HD#4, dobhoff placed and tube feeds started. That night, the patient’s respiratory status worsens and he is intubated.

What do you think? What do you do?

HYPOPHOSPHATEMIA• “Refeeding Syndrome”

– malnutrition– alcoholism

• Hypophosphatemia– limits oxygen unloading– immunocompromise– muscle weakness failure to wean

Treatment• IV supplementation in emergent cases

– sodium or potassium phosphorous

• PO supplementation routinely

• Keep (phosphorous x calcium) ratio < 60

• Magnesium should be replenished simultaneously

The burn patient

25 year male, caught fire after his lawnmower exploded as he was filling it with gasoline while smoking a cigarette.

The patient sustained second and third degree burns estimated at 40 % total

body surface area.

Parkland Formula4 cc x WEIGHT (kg) x (% TBSA)

Parkland Example

• 25 year old male

• weight = 220 pounds

• 40% TBSA 2° - 3° burns

• How much fluid do you need to give?– During the first 8 hours?– During the next 16 hours?

Parkland Example

4 cc x weight x %TBSA

4 x 100 x 40 = 16,000 cc/24 hours

first 8 hours = 16,000/2 =8,000/8 = 1,000cc/hr

next 16 hours = 8,000/16 = 500cc/hr

Diarrhea Dysrhythmia

• 68 yo female on digoxin for chronic CHF, presents to the SIU for colitis as evidenced by copious diarrhea.

• The patient is weak and lethargic and ectopic beats are noted on her ECG.

What do you think? What do you do?

Hypokalemia

• Deficits– Serum K =

• 3-4 is a 100-200 mEq deficit• 2-3 is a 200-400 mEq deficit

• Treatment– replacement 10 mEq/hr via peripheral IV– 10 mEq 0.1 mEq/L increase in serum K– Remember to check the Mg level too

Paradoxical Aciduria

• A rule: 0.1 pH 0.4 - 0.5 mEq [K+]

• pathophysiology– loss of K, severe alkalosis, [Na+] load– hydrogen exchanged for K– independent of alkalosis remaining

• requires emergent replacement

Cancer• 72 yo female with stage 4, metastatic

breast cancer.

• Patient is confused, cachetic, and nauseated

• Na+= 147, Ca+2 = 14mg/dl

What do you think? What do you do?

HYPERCALCEMIA

• Cancers associated with hypercalcemia– bone– breast– kidney– colon– thyroid– multiple melanoma

• Treatment– hydration– diuretics-lasix– mithramycin– corticosteroids– calcitonin-

osteoclast resorption

– phosphate

Labor and Delivery

32 year old P3G3 being treated by OB for eclampsia. You are called for a

somnolent patient in second-degree heart block and paralysis.

What do you think? What do you do?

Hypermagnesemia• Signs

– Prolonged PR interval– Hypotension, hyporeflexia, paralysis

• Treatment– Calcium gluconate– Normal saline– Loop diuretics– dialysis

Questions?Questions?