Diffusion describes a property of substances in water. Substances in water tend to move from an area of high concentration to an area of low concentration. special dialysis fluid, flows by the opposite side. A semipermeable membrane is a thin layer of material that contains various sized holes, or pores. Smaller solutes and fluid pass through the membrane, but the membrane blocks the passage of larger substances (for example, red blood cells, large proteins). The concentrations of solutes (for example potassium, phosphorus, and urea) are undesirably high in the blood, but low or absent in the dialysis solution and constant replacement of the dialysate ensures that the concentration of undesired solutes is kept low on this side of the membrane. The dialysis solution has levels of minerals like potassium and calcium that are similar to their natural concentration in healthy blood. For another solute, bicarbonate, dialysis solution level is set at a slightly higher level than in normal blood, to encourage diffusion of bicarbonate into the blood, to act as a pH buffer to neutralize the metabolic acidosis that is often present in these patients.
Tunneled is better because it uses less area of the actual vein which provides less risk for stenosis in the future and loss of access in the future.
Enough of this, what do I really need to know.
Dialysis(Intern’s Guide to Eckel) Intern Boot Camp 7/6/2010
Why the boot camp lecture? Most do not get ample exposure to patients on hemodialysis during medical school Patients on hemodialysis have a different set of medical problems that are unique to them. We’ll try to make this short and simple.
Objectives - Types of Dialysis - Access - Acute Indications for Dialysis - What do I need to know to survive Eckel - Cases of common admissions and overnight issues
Types of Dialysis That You Should Be Aware of 1. Hemodialysis 2. Peritoneal dialysis – just be aware of it’s existence 3. CVVH / CVVHD / CVVHDF – mostly seen in the ICU setting and can be grouped into one entity
Hemodialysis Hemodialysis -Dialysis works on the principles of the diffusion of solutes and ultrafiltration of fluid across a semi-permeable membrane. Hemodialysis removes wastes and water by circulating blood outside the body through an external filter that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite. This maximizes the concentration gradient of solutes between the blood and dialysate Ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane. This usually is done by applying a negative pressure to the dialysate compartment of the dialyzer. This pressure gradient causes water and dissolved solutes to move from blood to dialysate, and allows the removal of several liters of fluid
Peritoneal DialysisPeritoneal dialysis - uses the same principles as before howeverrather than extracorpeal membranes, uses patients own peritonealmembrane to move solutes across. Place dialysate bath intopatient’s abdomen. May have a few patients on this on the Eckelservice
CVVH / CVVHD / CVVHDF WHY SO MANY ACRONYMS???? Continuous veno veno hemofiltration, continuous veno veno hemodialysis, Continuous veno veno hemodiafiltration You’ll see this in the ICU setting in patients who have acute renal failure and volume overload. This basically allows for fluid removal through ultrafiltration and convection (high to low pressure system) as well as dialysis for solute removal in patient’s who may not be able to tolerate intermittent dialysis. Allows for less drastic fluid shifts and hypotension. Goes on for 24 hours a day. Do to the high volume of ultrafiltrate that is produced, know that fluid replacement is needed to to restore ideal fluid balance. You can either just have- hemofiltration (no dialysate, replacement fluid, moderate solute removal and large fluid removal)- hemodialysis (dialysate, no replacement fluid, large solute removal, less fluid removal- combination of both with dialysate and replacement fluid
An Attempted diagram to Make you Understand Dialysate Replacement Fluid Ultrafiltrate Pump Dialysate Pump Fluid Pump Hemofilter Blood PumpFrom the Air DetectorPatientTo The Patient
One slide on access.This includes AV fistulas, grafts, temporary lines or permanent central access lines that are tunneled.Fistulas are the preferred access type but take 3-6 months to mature. Grafts are used when you don’t have good veins/arteries next to each other and they don’t take as long after insertion to use. Complications of these include thrombosis, infections and aneurisms, and outlet obstruction.Lines are common with our patients in the hospital because the most common admission on the eckel service is line infection or probable line infection.KNOW THEIR ACCESS. FYI – When you try to order a picc line on a patient who is on dialysis, the picc line nurse will likely say no and that you need nephrology approval. This is because picc lines use potential areas for future access so we prefer not putting them in. If access is really needed for a long period of time, you can order a tunneled picc line to be put in by IR.
Eckel Admissions – Must KnowMr/Ms ________ is a ____ y/o with a hx of esrd or not (CKD stage __) 2/2 ______ on hemodialysis _______via ______ at __________ - also know dry weight - inter-dialysis weight gains - last dialysis session - full session or not - their nephrologist’s name - nutritional status - code statusGold Star - If their admission pertains to missed dialysis session, hypotension during dialysis, anything to do with dialysis, you can get the flow sheets from the dialysis center by calling them. They will fax that last few sessions to you and will document vitals and bp during session, febrile or not, medications that were given during dialysis. Know if they get any medications during dialysis such as antibiotics, epogen etc.
Now this is getting good. What else? Give me more, give me more!! - Dosing of meds - always check renal dosing on medications or HD dosing. These are not the same as what you usually have to prescribe. This is important because HD patients do not clear meds the same way as others might, must check dosing of medications. - ABX dosing - many abx are given as loading doses and then dosed after dialysis. Remember common ones such as vanc and gent which are given as loading doses and then dosed during/after dialysis depending on vanc or gent levels. (Vanc dosing is usually 20 mg/kg loading and then 500 mg after dialysis, gent is 1.5 - 2 mg/kg loading dose, then 1 mg/kg maintenance) - Medications not to give to HD patients - fleet enemas, mri gad, magnesium and phosphate, morphine! CHECK DOSING, CHECK DOSING, CHECK DOSING
Case 1 62 y/o female with pmh of esrd (not initiated on dialysis yet who is on the transplant list, (baseline creatinine 7) htn, dm presents from an osh with complaints of chest pain x 5 days, generalized fatigue and malaise. Patient on arrival to UH MICU was unstable with temperature of 39.0, tachycardia into 140’s, blood pressure into systolics of 70’s, with respirations 24. On exam, patient is alert and oriented, conversive, has flat neck veins, slightly decreased breath sounds over left base, cv exam remarkable for tachycardia and no pericardial rub, no abdominal pain, trace pedal edema, foley catheter with dark urine.
Laboratory evaluation as below. 131 / 104 / 126 / --------------------- < 117WBC 10, HGB/ HCT 11.4 / 35.9, PLT 195 5.5 / 7 / 10.9What more would you like?- if you asked for a blood gas, ph was 7.07- Coagulation panel showed inr of 10.2 as patient was on coumadinWhat abnormalities do you see on hx, exam, and labs?- Decreased breath sounds suggesting possible pna- Vitals signs- Anion Gap Metabolic Acidosis (as well as a non anion gap metabolic acidosis)- Upper limit of normal potassium- Acute on Chronic Renal Failure- Hyponatremia (likely hypovolemic hyponatremia)- UremiaDoes this patient need Dialysis?
ACUTE INDICATIONS FOR DIALYSIS Creatinine level is not an indication for dialysis Remember your vowels - A – Acidosis (metabolic acidosis) - E - Electrolyte Abnormalities (hyperkalemia) - I - Ingestants/Toxins (lithium) - O – Overload (volume overload causing respiratory distress) - U – uremia (systemic effects – uremic encephalopathy, uremic pericarditis)
Case 2 Patient is a 42 y/o female with esrd 2/2 lupus nephritis on HD mwf via left radial av fistula who presents to ED with compalints of muscle cramps. Vitals signs are T 36.3 / hr 97 / bp 109/68 / r 20 Exam is significant for 1+ edema b/l in lower extremities. Laboratory evaluation shows a renal function panel as below. 132 / 109 / 36 -------------------- 142 6.3 / 22 / 7.3- What is your next step?
Common AdmissionsHYPERKALEMIAQuestions to ask - did they miss a dialysis session - was their dialysis session cut short - inadequate dialysis session - did they eat an extra banana for breakfast - dietary indiscretion - any new medicationsFollow C a BIG K Drop (Calcium, B-agonist/Bicarbonate, Insulin, Glucose, Kayexalate, Dialysis)
Case 3 Mr. Jackson is a 55 y/o female with esrd 2/2 hypertensive nephrosclerosis on hd t/t/s via right tunneled ij line who presents from his HD session with hypotension. Patient’s session was cut short 2/2 to blood pressure systolic drop into 70 systolic. Currently patient is without complaints.- What are the different causes of hypotension during dialysis?
Case 3 ContinuedHYPOTENSION during dialysis - too rapid or excessive fluid removal removal - acetate in dialysate - heat-related vasodilation - underlying conditions (eg, autonomic neuropathy, myocardial ischemia, arrhythmias) - sepsis
Case 3 continuedMr. Jackson was admitted to the hospital for low blood pressures. Overnight, Odessa the secretary on LK40 calls you stating the nurse just took his temperature and it is 38.4.You look at your signout and realize you don’t have a signout on Mr. Jackson. Now what?You now head over to LK40 to read the admission note which states that the patient was admitted for hypotension during dialysis, is usually hypertensive and now has spiked a temperature. Patient had a temperature during dialysis of 38.0 based on dialysis flowsheets in the chart. What are you thinking?- Could this patient be septic?- Next steps?
Case 3 Continued You go an examine the patient and notice vital signs of 38.3 / 110 / 90/60 / 22 On exam of the right tunneled ij, you noticed some erythema and tenderness at the line site, no active drainage from the catheter site? Now what? Labs? Meds?
Things that go bump in the night……FEVER - common things common (pneumonia, uti (make sure they are not anuric), line infections, diarrhea, osteomyelitis - Line infection – Make sure you look at the line - exit site infection, tunnel infection, catheter related bacteremia. Treatment options include catheter removal, change catheter over guide wire, antibiotic locks and catheter salvage. This depends on the speciation of the organism.
Things that go bump in the night……SHORTNESS OF BREATHQuestions to ask - did they miss a dialysis session - was their dialysis session cut short - inadequate dialysis session If they make urine, you can give trial of diuretic (high dose lasix or bumex if blood pressure allows) If they don’t make urine, will they make it to their next dialysis session - remember those things that pertain to all patients – PE, pleural effusions, pna, pericardial effusions (htn medications)
Things that go bump in the night……Hypertension – Stuck between a rock and a hard place.- Treat the hypertension with prn antihypertensives, increasing the next doses of medications that are already given.- Do not want the patient to go into hypertensive emergency and flash pulmonary edema however the patient needs adequate blood pressure for perfusion (normal at higher blood pressures, need to perfuse access site as well as need adequate blood pressure for next dialysis session.)
Things that go bump in the night……Bleeding Post Dialysis- Not much you can do about this as most ESRD patients have thrombocytopenia and platelet dysfunction.- PRESSURE, PRESSURE, PRESSURE- In the ICU setting, can consider DDAVP however not used very often.
Things that go bump in the night…… Low Blood Counts- You will likely get called on a patient’s morning CBC by a nurse. This is likely not acute and if it is, pay attention to next week’s boot camp lecture by Dr. Tannous on GI bleed.- Remember in most cases, DO NOT give blood overnight. Give blood with dialysis. (general rule, give abx during or after dialysis, give blood during or after dialysis, get labs during or after dialysis.
Questions? Remember- ALWAYS GO ASSESS THE PATIENT- YOU ARE NEVER ALONE, IF YOU NEED HELP, CALL YOUR SENIOR
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