2A 43 year old male presented to emergency department with confusion HistoryRecurrent attacks of difficulty in passing urine , urine volume was decreasing over the last month together with sever burning sensation.Recurrent attacks of fever during the last 2 weeks with incomplete antibiotic courses.History of acute lumbar disc prolapse with severe back ache & heavy use of analgesics ( diclofenac, ketorlac, feldine……) over the last 3 months.
3On examination Vitals: BP 80/50 mmHg HR 135 bpm, regular Temp. 35˚C RR / min.Cold ,pale peripheral extremitiesDelayed capillary fillingWeak peripheral pulsationsChest exam.: Bilateral harsh vesicular breathingbilateral fine basal crepetationPupils equal medium size & reactiveNo lateralizing manifestationPatient is confused, not cooperative, not communicating
4Laboratory data Complete blood count (CBC) Hemoglobin (g/dl) 10.5 Hematocrit (%) 29Platelet count 86,000WBC (cells/ml) 20,000Segmented neutrophils 85%Band forms %
6Arterial Blood Gases Urine analysis Imaging pH 7.27 pCO2 30 pO2 58 HCO3 15O2 Sat % 93Urine analysisLeukocytes HPFNitrite veImagingCXR hilar congestive shadowRenal US Normal appearance
7What is your diagnosis?What is your first line of treatment?What further investigation would you like to request?would you like to consult other specialty(s)?
8Management Patient admitted to ICU & put on mechanical ventilation Central line was inserted, CVP measured, it was 12 cm H2O. IV crystalloid was initiated guided by CVPArterial line was inserted & invasive blood pressure was monitored. BP was 75/40mmHgNoradrenalin infusion was started at rate of 150 nanogram /kg/ min.Foly’s catheter was inserted , only 20 ml of urine was there
9Anti biotic was started empirically based on Antibiotic protocol for treatment of community acquired UTI ( 4th generation Cephalosporin started with renal adjustment of the dose)Sepsis screening done as blood & urine culture was send to microbiology lab.
10Would you initiate any RRT for this patient? Why?What type of RRT would you use?
11Nephrologist was consulted & he recommended initiation of CRRT in the form of CVVHDF CVVHDF was started through RT femoral venous catheterForty-eight hours after CRRT was started, patient’s potassium level was 3.5, his creatinine level was 6.3, and his BUN was 57. Potassium was added to his intravenous fluids and his electrolytes continued to trend toward normal.
12After five days of the initiation of antibiotic, patient’s sepsis was slowly resolving and he was weaned from both the ventilator and his vasoactive drips.IV antibiotics were continued until day 14 of hospitalization.patient’s renal function returned and he was discharged from the hospital on day 18
13Acute renal failure and renal replacement therapy in the ICU Acute renal failure (ARF) is a sudden and sustained fall in the glomerular filtration rate (GFR) associated with a loss of excretory function and the accumulation of metabolic waste products and water.It leads to rising serum urea and creatinine, usually with a fall in urine output.Up to 10% of all patients admitted to the ICU receive some form of renal replacement therapy.
14Types of RRTRRT classified according to the intended duration of each treatment (intermittent vs continuous) and, in the case of continuous, both the access (arterial vs venous) and the circuit type (dialysis vs filtration).CRRT usually involves the removal and return of blood through a single cannula placed in a large vein (venovenous therapy), arteriovenous Haemofiltration is of historical interest only.
15Intermittent VS continuous Venous VS arterialDialysis Vs filtration
16When? Intravascular volume overload unresponsive to diuretic therapy; Hyperkalemia refractory to medical management.Severe metabolic acidosis.Persistent oliguria or anuria, unresponsive to volume administration.Overt uremic symptoms (encephalopathy, pericarditis, bleeding diathesis); andProgressive azotemia in the absence of specific symptoms.
17Important considerations There is still no generally accepted azotemia threshold for when to start RRT.A better term is acute kidney support as it is analogous to mechanical ventilatory support;Therapy should be considered in patients with marked impairment in organ function and not limited to patients with complete failure.There is consensus that therapy should begin before complications develop.
18How? What is renal replacement therapy? There are two main physical processes that are employed to carry out the kidneys' function of the removal of solute and water from the body and thereby maintain a steady state:* Haemofiltration* HaemodilaysisRenal replacement systems may rely predominantly on Haemofiltration (convection) or haemodialysis (diffusion) but there are also systems that combine the two methods.
19Haemofiltration process Convection describes a process by which solutes are transported across a semipermeable membrane together with the solvent by means of filtration driven by a trans-membrane pressure gradientConvection removes middle molecular weight proteins of 5000–50,000 Da.
20The transmembrane pressure existing from one side of the hemofilter to the other leads to the passage of solvent (plasma water), bringing with it the passive flow of solutes it contains.
21Many of the septic mediators (e. g Many of the septic mediators (e.g. cytokines, complement) lie within this group. These mediators are absorbed onto the filter membrane and so removed.Interest surrounds the use of high volume Haemofiltration to remove these inflammatory mediators to improve outcome from severe sepsis.High volume filtration is defined as ultrafiltration of over than 2 liters/hour, and there is evidence that filtrate volumes up to 6 liters/hour are associated with a significantly lower mortality in septic patients.
22Haemodialysis process Diffusion describes a process passive transport of solute across a semi-permeable membrane driven by a concentration gradient such that the solute will tend to an equal concentration in the available distribution space on both sides of the membrane ( from blood to dialysate)Blood flow and dialysate flow rates are set in order to obtain the best compromise between maximum diffusion and good hemodynamic tolerance.
23The conventional dialysate flow rate is about 500 mL/min and the blood flow rate is about 300 to 500 mL/min.Diagram of a haemodialysis circuit. In green: dialysate. In yellow: used dialysate.
24Hemodialysis allows the passage of small molecules (with molecular weights of 500 to 5,000 Da) from blood to dialysate.Therefore, it allows the removal of many metabolic waste products and can maintain good electrolytic homeostasis.The main side effect of IHD is the possibility of poor hemodynamic toleranceSustained, low-efficiency dialysis (SLED) and continuous haemodialysis are sub-modalities in which the duration of dialysis is extended (6 to 12 h or even 24 h), allowing for more gradual removal of solutes and fluid and hence better hemodynamic tolerance.
25HaemodiafilterationDiagram of continuous heamodiafiltration. In green: dialysate. In pink: replacement fluid (postdilution). In yellow: ultrafiltrate plus used dialysateDiagram of continuous Haemofiltration. In yellow: ultrafiltrate. In pink: replacement fluid (post dilution).
26Why CRRT?Reduces hemodynamic instability preventing secondary ischemiaAcid base balanceElectrolyte managementAllows for improved provision of nutritional supportManagement of sepsis/plasma cytokine filterSafer for patients with head injuriesProbable advantage in terms of renal recovery
28How much?For continuous haemofiltration, intensity can be more readily quantified by the ultrafiltration flow rate, commonly expressed as ml/kg/h of ultrafiltrate. Early results from single-center trials showed that increasing the ultrafiltration rate was associated with improved survival in critically ill patients with AKI.25 to 30 ml/kg/h be prescribed in the hopes of achieving the 19 and 22 ml/kg/h is recommended
29Dose of CRRT Dose = amount of solute clearance CRRT = Effluent flow MonitorTime-averaged serum urea
30Dialysis dose: One size does not fit all! Modifications required based on:Protein catabolic ratePatient weightInterruptionsRecirculation
31ComplicationsCircuit and haemofilter thromboses lead to reduced efficiency of the RRT and possible blood loss.During a haemodialysis session, back-diffusion can be observed if the transmembrane pressure becomes negative. It means that molecules pass from the dialysate to the blood compartment. It is necessary to provide a minimum ultrafiltration flow rate across the membrane to avoid this phenomenon.The use of heparin can be responsible for bleeding and heparin-induced thrombocytopenia.
32Poor hemodynamic tolerance may occur Poor hemodynamic tolerance may occur. The main causes include rapid solute removal (IHD) and hypovolemia induced by the removal of plasma water from the blood compartment. The preservation of a relative hemodynamic stability during the RRT session is probably the most difficult goal to achieve. Recurrent episodes of hypotension must be avoided because they can perpetuate organ injury and likely delay renal recovery.
33Numerous complications are linked to the use of the catheter Numerous complications are linked to the use of the catheter. Depending on the venous site (femoral, subclavian, or internal jugular), complications of catheter insertion include arterial puncture, local bleeding, hematoma, pneumothorax, hemothorax, retroperitoneal bleeding, or cardiac arrhythmia. The use of guided insertion procedures, such as ultrasound, has reduced both the incidence of these complications and the rate of catheter insertion failure. Once inserted, catheters may also result in several mechanical problems (eg, malpositioning), thrombosis, and infections.
34Drug removal/dosing Factors to consider Drug Molecular Weight Volume of distributionProtein bindingIonic chargeAN 69 cut-off 56,000 DaltonsSolute with a molecular weight > 56,000 will not be removedUrea= 60Creatinine=117Albumin=62 000Vancomycin=1449
35Special Attention Close management of laboratory values: PotassiumPhosphateMagnesiumNutritional assessment due to amino acid and other nutrient losses during CRRTHypothermia