1. Mini Lecture: IV Fluids William Graham, PGY2 January 2014 Department of Medicine UC Irvine Medical Center

2. * Objectives Understand daily fluid and electrolyte requirements for an average adult Understand the major components of replacement fluid Maintenance vs. Resuscitation Complications of fluid therapy

3. * Water Input and Output of the “Normal” Adult Minimal Obligatory Daily Water input: – Ingested water: 500mL – Water content in food: 800mL – Water from oxidation : 300mL TOTAL: 1600mL Minimal Obligatory Daily water output: Urine: 500mL Skin: 500mL Respiratory tract: 400mL Stool: 200mL TOTAL: 1600mL → Average adult input/output is 30-35mL/kg/day (2.4L/day)

4. * Contents of IV Fluid Preparations Na (mEq/L) K (mEq/L) Cl (mEq/L) HCO3 (mEq/L) Dextrose (gm/L) mOsm/L D5W50278 ½ NS77 143 D51/2NS77 50350 NS154 286 D5NS154 50564 Ringers Lactate (RL) 13041092850272

5. * Daily Electrolyte Requirements - Sodium: 100-250meq (western diet) – mostly excreted in urine - Potassium: 50-100meq – mostly excreted in urine, 5% in feces - Chloride: 60-150meq – Example: 1/2NS @ 100cc/hr provides ~180mEq of sodium and chloride/day! -this is why NS should not be used for maintenance fluid in patients with normal renal function- risk of hyperchloremic metabolic acidosis - Bicarb: 1 meq/kg/day

6. * Case Vignette 58 y/o male with h/o HTN, dyslipidemia, admitted for cough and atypical chest pain. Found to have abnormal CXR and CT Thorax concerning for malignancy. Kept NPO overnight for possible bronchoscopy with biopsy in the morning. He is placed on NS @ 75cc/hr. 1. Was the right solution picked? 2. Is the rate correct?

7. * Maintenance Therapy Purpose: Replace ongoing losses of water and electrolytes under normal physiological conditions - Used when the patient is not expected to eat or drink normally for prolonged period of time - In general, patients who are afebrile, not eating, not physically active require less that 1 L of free water daily - Patient’s with ESRD or edematous states (ex. cirrhosis, heart failure) require less maintenance due to decreased output and/or altered fluid distribution

8. * Maintenance Therapy 3 approaches to determine the appropriate rate: 1) Calculate maintenance based on average requirement of 35cc/kg/day 2) “4/2/1” rule 4 ml/kg/hr for the first 10 kg (0-10kg) 2 ml/kg/hr for the next 10kg (11-20kg) 1 ml/kg/hr for remaining weight (21 kg and up) 3) Weight in kg + 40 Vignette: Pt weight 85kg. –85kg x 35cc/kg/24hr= 3L/24 hr= 125cc/hr –40 + 20 + 65 = 125cc/hr –85 + 40 = 125cc/hr

9. * Maintenance Therapy What type of fluid for maintenance? - D51/2NS + 20 mEq KCl provides: a) ~180 mEq/day sodium and chloride (100-250 sodium and 60-150 chloride needed/day) b) ~50 mEq/day potassium (50-100 mEq needed/day) -avoid dextrose in patients with uncontrolled DM or hypokalemia -not much data to support addition of D5, however can be added to prevent muscle catabolism - Therefore, 1/2NS or D51/2NS + 20 mEq KCL would be appropriate choices. - adjust maintenance fluids based on serum sodium concentration (ex. Change from 1/2NS to NS or D5NS if hyponatremia develops)

10. * Clinical Vignette 86y/o female admitted with nausea and vomiting and c/o rectal bleeding. She has a history of recent admission for CHF exacerbation. Weight is 45kg. SBP 80’s in the ED. She is started on IV pantoprazole. 1. What is your initial choice of fluids?

11. * Fluid Resuscitation Purpose: Correct existing abnormalities in volume status or serum electrolytes Objective parameters used to assess volume deficit: Blood pressure Jugular venous pressure Urine sodium concentration Urine output Pre and post deficit body weight

12. * Rate of Repletion Severe volume depletion or hypovolemic shock ? -> Rapid infusion of 1-2L isotonic saline (NS), then reassess parameters - use Lactated Ringers if concern for re-expansion acidosis (ex. acute pancreatitis) Mild to moderate hypovolemia ? 1) Estimate fluid losses: –Recall: Average output 2.4L/day for 70kg patient –estimate additional losses such as GI (diarrhea, vomiting) and high fever -> add 100ml/day for each degree of temp > 37C 2) Choose rate 50-100mL/h greater than estimated losses 3) Select fluid based on type of fluid that has been lost and any co-existing electrolyte disorders

13. * Clinical Vignette 86y/o female admitted with nausea and vomiting and c/o rectal bleeding. She has a history of recent admission for CHF exacerbation. Weight is 45kg. SBP 80’s in the ED. She is started on IV pantoprazole. 1. What is your initial choice of fluids? 2. She is kept NPO for EGD and colonoscopy the next morning. After receiving 2u PRBC and normal saline you decide to start maintenance fluids. What rate and type of fluid do you choose?

14. * Complications of IVF The team decides to put her on D51/2NS @ 125cc/hr. Her repeat serum sodium level is 130 the next morning and she is complaining of some SOB. She is thought to have an infiltrate on CXR and started on IV Zosyn and Vancomycin for hospital acquired pneumonia. 3. What could be contributing to the hyponatremia? 4. What is likely contributing to the SOB?

15. * Where is my bolus going? 1L D5W distributed into Total Body Water Interstitial 226cc Intra- vascular 114cc!! Normal saline has no free water and is confined to ECF space; this is why it is the preferred IVF for resuscitation! Free water content ICFECFInterstitialIntravascular D5W1000cc660cc340cc226cc114cc (11%) ½ NS500cc 500330cc + 55cc from free water content 170cc + 55cc =225cc (22%) NS001000cc660cc330cc (33%)

16. * Summary Treat IV fluids as a prescription just like any other medication, with consideration of renal function and clinical picture Determine if patient needs maintenance or resuscitation Choose fluid type based on co-existing electrolyte disturbances Don’t forget about additional IV medications patient is receiving Choose rate of fluid administration based on weight and minimal daily requirements Avoid fluids in patients with ECF volume excess Assess DAILY whether the patient continues to require IVF