Fluid Therapy. Leo Roa, DVM ACVECC

Transcription

1 Fluid Therapy Leo Roa, DVM ACVECC

2 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.

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4 Estimate % interstitial dehydration < 5 %: Not detectable %: Evidence of hypovolemia 5 6 %: Tacky MM 6 8 %: Decreased skin turgor > 12 %: Hypovolemic shock and death 8 10 %: retracted globes into orbit

5 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

6 Osmolality Osmolality (mosm/kg) = 2 (Na + K) + (BUN/2.8) + (Glu/18) Dogs: Cats: 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

7 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

8 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

9 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

10 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: ml/kg/day Cats 10 ml/kg/day

11 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

12 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.

13 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.

14 Albumin and FFP Physiologic functions of albumin COP Wound healing and Coagulation Scavenges free radicals Transport of cations, bilirubin, drugs, etc. You need ml/kg of FFP to raise albumin by 1 gram/ dl. Human albumin may induce life threatening side effects.

15 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

16 Shock Correction Hypovolemic shock Cardiogenic shock Distributive shock Hypoxemic shock

17 Stages of shock Compensatory 15-30% ECF loss Early Decompensatory 30-40% ECF loss Late decompensatory >40% ECF loss Heart Rate Increased Increased Decreased MM Hyperemic Pale Pale CRT Rapid Prolonged Prolonged Pulse Quality Blood Pressure Normal to bounding Normal to increased Normal to decreased Normal to decrease Weak Decreased Core Temp Normal Normal Decreased

18 Distributive Shock

19 English Shepherd 11 yr old MN Max Coughing and soft stools x 3 days Owner gave aspirin RDVM No diagnostics Dx Kennel Cough Tx Amoxicillin Hydrocodone

20 3 days later Not eating Worsening cough Thoracic radiographs Pleural effusion Cardiomegaly Blood work sent out Dx Cardiomyopathy Pleural effusion Tx Furosemide

21 RDVM Bloodwork 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) 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

22 Clinical Evaluation WT 30 kg HR 200 RR 100 Muffled heart sounds Weak femoral pulses Pale MM

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24 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?

25 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

26 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

27 Distributive / Hypovolemic Shock

28 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 F LOC Obtunded CRT 3 sec MM pale Generalized weakness, but ambulatory

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30 Fluid therapy Approach IV catheter 2 Large bore (14 18 G) Crystalloids Pressure Bags Control pain Gastric decompression Trocarization Gastric tube

31 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

32 Fluid therapy Approach Early goal therapy HR Systolic > 90 mmhg Mean > 70 mmhg Improvement in Lactate by 50% (4-6 hr) Mentation CRT Femoral pulses Dorsopedal pulses

33 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.

34 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

35 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

36 Post Op Care Lidocaine use VPCs with HR > 150 bpm Multiform VPCs Reduces ischemia reperfusion Injury Goals Control arrhythmia Control pain Maintain tissue perfusion

37 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

38 Hypovolemic shock

39 Ziggy year Dachshund Presentation Referral Abdominal mass Lethargy Normal appetite, defecation and urination TPR Temp= HR= 120 RR= 40 Pale pink BW WBC = HCT = 27% Platelets = 48,000 Chemistry ALB = 2.7 GLU = 115 TBILI = 0.3 Imaging Thoracic radiographs Abdominal radiographs Abdominal ultrasound

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44 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).

45 End point resuscitation End point resuscitation goal Blood pressure systolic 90 mmhg with a HR 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

46 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.

47 Cardiogenic Shock

48 8 year old Saint Bernard Referred for Cough Leo Collapsing episodes Currently being treated for pneumonia Clavamox oral Baytril oral

49 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

50 Blood work at RDVM

51 Post Diltiazem

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56 Therapy instituted Pimobendan Diltiazem Furosemide Oxygen support IV fluids are contraindicated in cardiogenic shock. Increases the chances of pulmonary edema

57 Leo improved with the treatment instituted ECG improved to bpm RR improved to 24 Oxygen dependency resolved. Discharge 24 hours post hospitalization Response

58 Hypoxemic Shock

59 10 year old Wheaton. Murphy Presented for respiratory distress and decreased activity. Vitals WT: 17.5 kg Temp F HR 160 bpm RR 64 bpm MM pink CRT 2 sec

60 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

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65 BAL and Blastomyces Ag

66 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.

67 Fluid therapy for hypoxemic shock 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 ml/kg/hr (1 to 1.5 maintenance). Careful with colloids.

68 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.