Fluid TherapyLeo Roa, DVM ACVECC

Goals Patient evaluation and determination of fluid status

Factors taken to determine most appropriate fluid

therapy.

Which factors determine improvement or worsening

of the patient status.

Estimate % interstitial

dehydration < 5 %: Not detectable

5 – 6 %: Tacky MM

6 – 8 %: Decreased skin

turgor

8 – 10 %: retracted globes

into orbit

10 – 12 %: Evidence of

hypovolemia

> 12 %: Hypovolemic

shock and death

Fluids available to us Crystalloids

Hypotonic: Lower osmolality than the blood.

Isotonic: Same osmolality as the blood.

Hypertonic: Higher osmolality than the blood.

Colloids

Synthetic Starch Colloids

Albumin (human vs canine)

Hemoglobin-based oxygen carrying solutions

Oxyglobin

Osmolality Osmolality (mOsm/kg) = 2 (Na + K) + (BUN/2.8) + (Glu/18)

Dogs: 290 – 310

Cats: 311 - 322

We divide by 2.8 and 18 to convert from mg/dL to mmol/L

Modified Osmolality

2 (Na) + Glu/18

Na and Glucose move easily between vascular and interstitial space

Electrolytes and glucose need a transporter to enter the intracellular space

Hypotonic Fluids Has a low osmolality

0.45% NacL

5% dextrose

Contains mostly free water

Additives are to increase the osmolality

Do not bolus

Disrupts idiogenic osmoles

Used to correct hypernatremia

Na > 170 mmol/L

Crystalloids Same osmolality as blood and are ideal fluid for

resuscitation.

Plasmalyte and Normosol use buffers such as

acetate and gluconate

Lactated Ringers

Lactate in LRS does not cause metabolic acidosis.

May artificially increase the lactate in blood.

#1 fluid used in neonates – Lactate = metabolic fuel

Hypertonic Saline Normally we use 7.4 % Hypertonic saline

Dose 3-5 ml/kg

Can combine 23.4% hypertonic saline with colloid

Ratio 1:2 / Dose 3-5 ml/kg

Follow with crystalloids

Improves cerebral perfusion

Rapid infusion promotes hyperosmolality which results in:

Vasodilation: central vasomotor inhibition

Bradycardia: peripheral vasomotor effects

Colloids Increases intravascular volume by 1.5 times

Dogs have 3x more amylases than people so they break colloids

faster.

Colloids will increase your specific gravity

Urine osmolality is a more accurate measure of urine concentration.

Dose

Dogs: 20 - 50 ml/kg/day

Cats 10 ml/Kg/day

Colloids in human medicine Currently banned in Europe

The risk of renal disease outweighs the potential benefits.

FDA recommends against the use of HES in critically ill patients

Acute Kidney Injury

Sepsis

Heart surgery

People on colloids were more like to

Develop Acute Kidney Injury

Increased need for Dialysis

Increased mortality rate

Increases the risk of bleeding

Colloids in Veterinary Medicine

Dogs are able to break down colloids more rapidly

than humans.

The incidence of acute kidney injury in dogs is not

as common.

The length of therapy is more detrimental than the

volume provided in 24 hours.

Can spike and draw the mount needed, the rest has

a shelf life of 4 weeks.

Evidence Has been demonstrated to reduce peripheral edema in

hypoalbuminemic dogs.

No apparent correlation with dose

Not all hypoalbuminemic dogs responded

In healthy dogs under anesthesia

Colloids increased BP in dogs receiving ISO.

Same volume of crystalloids were not as efficacious in increasing

BP when under ISO.

Albumin and FFP Physiologic functions of albumin

COP

Wound healing and Coagulation

Scavenges free radicals

Transport of cations, bilirubin, drugs, etc.

You need 40-50 ml/kg of FFP to raise albumin by 1 gram/ dL.

Human albumin may induce life threatening side effects.

Daily fluid therapy A) Calculate fluid deficit

% dehydration x Weight in Kg

B) Estimate fluid losses

C) Maintenance

Dog: 60 ml/kg/day

Cat: 40 ml/kg/day

Can use RER formula

30 (BW Kg) + 70/day

Shock Correction Hypovolemic shock

Cardiogenic shock

Distributive shock

Hypoxemic shock

Stages of shock

Compensatory15-30% ECF loss

Early Decompensatory30-40% ECF loss

Late decompensatory>40% ECF loss

Heart Rate Increased Increased Decreased

MM Hyperemic Pale Pale

CRT Rapid Prolonged Prolonged

Pulse Quality Normal to

bounding

Normal to

decreased

Weak

Blood Pressure Normal to

increased

Normal to

decrease

Decreased

Core Temp Normal Normal Decreased

Distributive Shock

Max 42998 English Shepherd

11 yr old MN

Coughing and soft stools x 3 days Owner gave aspirin

RDVM No diagnostics

Dx – Kennel Cough

Tx Amoxicillin

Hydrocodone

3 days later Not eating

Worsening cough

Thoracic radiographs

Pleural effusion

Cardiomegaly

Blood work sent out

Dx

Cardiomyopathy

Pleural effusion

Tx

Furosemide

RDVM Bloodwork Following day

Systolic 116

Diastolic 76

Mean 91

ECG – results were pending

Muffled heart sounds

Dx Pericardial effusion

Cardiac tamponade

Following day referred for echocardiogram

CBC

HCT = 27% (low)

WBC = 4.4 (low)

Platelet = 124K (low)

Chem

ALB = 2.8 (Low normal)

ALT 144 (high)

TBILI = 0.3 (High normal)

BUN = 8 (normal)

CREA = 0.7 (normal)

Clinical Evaluation WT 30 kg

HR 200

RR 100

Muffled heart sounds

Weak femoral pulses

Pale MM

Case Approach I tend to hold off on IV fluids

First step is to pursue pericardiocentesis

Once the pericardium is addressed then

What is the heart rate doing?

Femoral pulses?

Dog’s mentation?

Capillary refill time?

Case Approach If cardiovascular stability ensues with

pericardiocentesis, then:

ECG monitoring x 24 hours

TFAST as needed to TID

No need to treat with IV fluids if patient is stable

If cardiovascular stability is not achieved:

Persistent tachycardia or hypotension

Consider

Crystalloid bolus 10 ml/kg + 5 ml/kg colloid.

Can repeat once or twice

Continue crystalloids at maintenance

Monitor future pericardial effusion or ascites

Distributive / Hypovolemic

Shock

Roscoe 6 yr old Labrador

Presentation

Non productive retching

Difficult walking

Groaning

Clinical findings

Pale gums

Cardiac arrhythmia

Weak femoral pulses

Painful distended abdomen

HR – 200 bpm

RR – 44 bpm

Temp - 98.5 F

LOC – Obtunded

CRT 3 sec

MM – pale

Generalized weakness, but ambulatory

Fluid therapy Approach

IV catheter

2 Large bore (14 – 18 G)

Crystalloids

Pressure Bags

Control pain

Gastric decompression

Trocarization

Gastric tube

Laboratory results BIG 4

PCV - 62%

TS – 7.2 gr/dL

Lactate 7 mmol/L

BG – 187 mg/dL

CBC

WBC – 17.8 k

Platelet – 140,000

Coags

PT 12 sec

PTT 89 sec

Chemistry

BUN – 55 mg/dL

Creat – 1.4 mg/dL

ALT 300 U/L

ALP 186 U/L

Na 145 mmol/L

K 3.6 mmol/L

Blood pressure

Systolic – 70 mmHg

Diastolic – 40 mmHg

Mean – 55 mmHg

Early goal therapy

HR – 100 – 130

Systolic > 90 mmHg

Mean > 70 mmHg

Improvement in

Lactate by 50% (4-6 hr)

Mentation

CRT

Femoral pulses

Dorsopedal pulses

Fluid therapy Approach

40 dogs admitted to the hospital with a GDV

Lactate > 6 mmol/L was not associated with gastric necrosis.

Survivors (37 dogs) decreased their lactate level by 50% within 12 hours

The 3 dogs with persistent elevation of lactate after 12 hours of treatment died.

Intra Op Fluid therapy

10 ml/kg/hr

Can reduce to 5ml/kg/hr once more stable

Minimize gas anesthesia

Consider MLK

Consider fentanyl

Reduces episode of hypotension

Avoid

Dex-domitor

Post Op Care Crystalloids

1 ½ - 2 times maintenance

Colloids?

Will use it intra-op

Post-Op will be based on

patient status

Monitor arrhythmias

Idioventricular rhythm

HR < 140 bpm with VPC

No need for TX

Lidocaine use

VPCs with HR > 150 bpm

Multiform VPCs

Reduces ischemia

reperfusion Injury

Goals

Control arrhythmia

Control pain

Maintain tissue perfusion

Post Op Care

Overall therapy Start using oral route as soon as possible

Offer food about 6 hours post surgery

If not eating consider NE tube

Start with ¼ to ½ RER

Start decreasing IV fluids once tolerating feedings

Maintain hydration via NE tube

Control pain IV or Oral route if tolerating feedings

Hypovolemic shock

Ziggy 44637 13 year Dachshund

Presentation “Referral”

Abdominal mass

Lethargy

Normal appetite, defecation and urination

TPR

Temp= 102.8

HR= 120

RR= 40

Pale pink

BW

WBC = 16.80

HCT = 27%

Platelets = 48,000

Chemistry

ALB = 2.7

GLU = 115

TBILI = 0.3

Imaging

Thoracic radiographs

Abdominal radiographs

Abdominal ultrasound

Permissive resuscitation This case is clearly having blood loss anemia due to

a splenic mass

Permissive resuscitation implies

Low volume fluid therapy

5-10 ml/kg bolus over 1 hour (can repeat one or

twice)

.

End point resuscitation End point resuscitation goal

Blood pressure systolic 90 mmHg with a HR 120 –140 bpm

Continue fluids at 3 ml/kg/hr (1.5 maintenance)

If permissive resuscitation does not improve cardiovascular stability consider blood transfusion.

Once bleeding is under control can further resuscitate the patient

Post – Op care IV fluids at 1 to 1 ½ maintenance

Offer food and water as soon as patients is

standing.

If not eating consider naso-esophageal tube.

If tolerating feedings, start to decrease IV fluids.

Maintain hydration via oral route.

Cardiogenic Shock

Leo 8 year old Saint Bernard

Referred for

Cough

Collapsing episodes

Currently being treated

for pneumonia

Clavamox oral

Baytril oral

Presentation Generalized weakness

Pale gums / CRT 3 sec

HR = 230 bpm

RR 60 bpm

Coughing

Increased lung sounds

Crackles caudal

Soft abdomen non painful

Cardiac arrhythmia

Questionable murmur

Asynchronous pulses/weak

Blood work at RDVM

Post Diltiazem

Therapy instituted Pimobendan

Diltiazem

Furosemide

Oxygen support

IV fluids are contraindicated

in cardiogenic shock.

Increases the chances of

pulmonary edema

Response Leo improved with the

treatment instituted

ECG improved to 100-120

bpm

RR improved to 24

Oxygen dependency

resolved.

Discharge 24 hours post

hospitalization

Hypoxemic Shock

Murphy 29378 10 year old Wheaton.

Presented for respiratory distress and decreased activity.

Vitals

WT: 17.5 kg

Temp 103.1 F

HR – 160 bpm

RR – 64 bpm

MM pink

CRT 2 sec

Murphy Physical exam

Sinus tachycardia with no evidence of murmur.

Weak femoral pulses

Increased lung sounds, but no evidence of wheezes or

crackles.

Soft abdomen, non painful

BAL and Blastomyces Ag

Fluid therapy for hypoxemic shock

Fluid therapy should be instituted to correct deficit.

Rapid fluid infusion of a large volume of fluid is not

recommended, since the capillaries could leak

more fluid into the lungs.

Crystalloid vs Colloids

The though that colloids are macromolecular and will

never leak into the interstitum is a wrong assumption.

Different pig models have demonstrated the leakage

of colloids into the parenchyma.

I usually start with short boluses of crystalloids of

5-10 ml/kg over 20 minutes.

Rapid institution of oxygen will help correct the

tachycardia at a faster rate.

Once shock is under control, continue crystalloids

at 2.5 – 3.5 ml/kg/hr (1 to 1.5 maintenance).

Careful with colloids.

Fluid therapy for hypoxemic shock

Conclusion Currently we are giving too much fluids to our hospitalized and

anesthetized patients.

Current guidelines advocate for rapid resolution of shock.

Reduce IV fluid therapy once hydrated.

Provide daily requirement and adjust based on losses.

Make an effort to use the GI tract as much as possible.

Offer water

Give water via feeding tube

Nasogastric or nasoesophageal feeding tubes should be considered if

Patient remains inappetent

Vomiting is under control.