Regarding contrast-induced nephropathy (CIN), which ONE of the following statements is FALSE?
Answer: C: The risk for CIN is very closely related to the existing renal insufficiency. An eGFR of <60 mL/min/1.73 m2 represents significant renal dysfunction and is used to define the patient at high risk for developing CIN. Similarly, the presence of other patient-related risk factors also increases the risk for CIN. These risk factors include diabetes, shock or hypotension, advanced age (>75 years), advanced congestive heart failure, sepsis and the use of nephrotoxic agents. Serum creatinine levels usually peak at 3 days after administration of the contrast medium. Subsequently, it is generally recommended that serum creatinine levels be repeated at 48–72 hours following contrast medium in all high-risk patients.
Recognition of the high-risk patient coupled with appropriate periprocedural management can reduce the incidence of CIN. Multiple studies have shown that parenteral volume repletion is the cornerstone of CIN prevention. However, data is still lacking regarding the optimal fluid regimen. One recommendation is to administer a total of at least 1 L of isotonic saline beginning at least 3 hours before and continuing at least 6–8 hours after the procedure. Initial infusion rates of 100–150 mL/hr are recommended with adjustment post procedure as clinically indicated. The appropriate caution should be taken in patients with reduced left ventricular function and congestive cardiac failure.
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Regarding pericarditis in patients with end-stage renal disease (ESRD) requiring chronic dialysis, which ONE of the following statements is TRUE?
Answer: C: About 20% (1 in 5 patients) of patients requiring chronic dialysis will develop pericarditis and it is usually due to either uraemia or dialysis related. Uraemic pericarditis is by far more common and is responsible for about 75% of cases. Interestingly, the pericardial friction rub associated with uraemic pericarditis is louder than in most forms of pericarditis and is often palpable. Furthermore, the inflammatory cells in uninfected uraemic pericarditis do not penetrate into the myocardium, therefore the typical ECG changes of acute pericarditis are absent. When the ECG has features typical of pericarditis it mandates a search for other causes including infection. The management of haemodynamically stable patients with uraemic and dialysis-related pericarditis is intensive dialysis; therefore, the dialysis team should be involved early in the diagnosis. Should the pericardial effusion persist for longer than 10–14 days with intensive dialysis, treatment is considered a failure and an anterior pericardectomy is usually performed.
Which ONE of the following statements is TRUE regarding complications of vascular access associated with haemodialysis?
Answer: A: Vascular access for haemodialysis is usually obtained with the creation of an AV fistula from a native artery or vein or, if this is unsuitable, a vascular graft. Grafts are associated with a higher complication rate compared with natural AV fistulas. This is significant considering that complications of vascular access account for more inpatient hospital days than any other complication of haemodialysis. Vascular access complications include failure to provide adequate flow for dialysis, infection, bleeding, vascular access aneurysm and pseudoaneurysms, vascular insufficiency of the extremity distal to the vascular access and high-output heart failure. Failure to provide adequate flow for dialysis and infection are by far the two most common complications. The inability to obtain adequate flow for haemodialysis is common. This is usually caused by thrombosis or stenosis and can clinically be determined when there is a loss of bruit and thrill over the access. This is not an emergency and can be treated within 24 hours by angiographic clot removal, angioplasty or by alteplase injection into the access. The ED clinician should rather focus on evaluating the patient for indications requiring emergency dialysis, as haemodialysis will inevitably be postponed until adequate flow is established.
The classic signs of pain, erythema and swelling of an infected vascular access are often missing. Patients more often present with signs of sepsis such as fever, hypotension or an elevated white cell count (WCC). Staphylococcus aureus is the most common infecting organism. Vancomycin is the drug of choice because of its effectiveness against methicillinresistant organisms and a long half-life (5–7 days) in dialysis patients.
Regarding renal transplant patients presenting to the ED, which ONE of the following is FALSE?
Answer: B: The kidney is the most commonly transplanted organ and is placed in the right or left lower quadrant of the abdomen; it is easily palpable on abdominal examination. These patients require lifelong immunosuppression to prevent rejection. Current available immunosuppressant drugs are more potent than those in the past and as a result, the incidence of rejection is now lower in these patients. However, it has contributed to a greater incidence of medicationrelated problems.
Two common causes of ARF after kidney transplantation are acute cyclosporine or tacrolimus nephrotoxicity and acute rejection. It is difficult to distinguish between these two disorders. Traditionally, fever and allograft tenderness favoured rejection; however, these findings are now rare with current immunosuppressive regimens. Elevated cyclosporine or tacrolimus blood levels make nephrotoxicity the more likely diagnosis. Blood levels should be obtained in all patients who present with ARF.
Fever is a common problem that brings renal transplant recipients to the ED. The causes of fever in these patients vary according to the time after transplant. Infections seen in the first post-transplant month are the usual postoperative infections seen in the general surgical population. Opportunistic infections are uncommon in the first posttransplant month and usually occur after the first month and before the first post-transplant year. Beyond the first year, opportunistic infections may still occur but community-acquired infections unrelated to immunosupression become more common.
The serum creatinine level is the most valuable prognostic marker of graft function at all times after transplantation.
Regarding calcium administration in severe hyperkalemia in patients with renal failure, which ONE of the following statements is TRUE?
Answer: B: In severe hyperkalaemia, intravenous calcium is effective in reversing electrocardiographic changes and reducing the risk of arrhythmias. Improvement of ECG is usually visible within 1–3 minutes. Calcium administration can be repeated if no effect is seen within 5–10 minutes. The duration of action is 30–60 minutes.
It is true that CaCl 10% is about three times as potent as Calcium-gluconate (10% CaCl = 27.2 mg [Ca2+ ]/mL; 10% gluconate = 9 mg [Ca2+ ]/mL. However, no specific Ca2+ preparation has been shown to be superior to the other and its use depends on clinician preference, patient factors and availability. The initial and repeat doses may need to be adjusted accordingly. CaCl 10% is more likely to cause tissue necrosis if it extravasates and should preferably be given via central line.
Calcium administration should be reserved for life-threatening situations in patients on digoxin. Calcium can potentiate cardiac toxicity to digoxin regardless of the serum Ca2+ levels. If the patient’s condition necessitates administration of Ca2+ , it is recommended to give it slowly over 20–30 minutes mixed in 100 mL of D5 W. An alternative is to consider using magnesium instead of calcium to stabilise the myocardium.
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