Following the implementation of citrate anticoagulation for continuous renal replacement therapy, we evaluate its first year of use and compare it to the previously used heparin, to assess whether our patients benefit from the recently reported advantages of citrate. We retrospectively analysed 2 years of data to compare the safety and efficacy of citrate versus heparin. The results have shown that 43 patients received continuous renal replacement therapy with heparin, 37 patients with citrate. We found no significant difference in metabolic control of pH, urea and creatinine after 72 h. Filters anticoagulated with citrate had significantly longer median lifespan (33 h vs 17 h; p ¼ 0.001), shorter downtime (0 h vs 5 h; p ¼ 0.015) and less filter sets per patient day (0.37 vs 0.67; p ¼ 0.002). Filters anticoagulated with heparin were commonly interrupted due to clotting (50% vs 16.4%), whereas filters anticoagulated with citrate were often stopped electively (53.4% vs 24.6%). Patients on heparin filters had significantly higher APPTs, some at potentially dangerous levels (>180 s), whilst patients on citrate filters had significantly higher levels of bicarbonate. Therefore, we conclude that citrate is superior in terms of safety and efficacy, with longer filter lifespan. It has become our first line anticoagulant for continuous renal replacement therapy.

Transdermal fentanyl patches are used frequently for the management of both acute and chronic pain. Adverse events with their use, in particular overdose, are not uncommon. We describe a case of fentanyl overdose from transdermal patch placed over a five-day old tattoo. The report will review the pharmacology of transdermal fentanyl and the physiology of tattooing, as well as the potential link between the two, which may have lead to the overdose. Keywords Fentanyl, transdermal patch, drug overdose, tattooingFentanyl is a potent opioid used to control acute and chronic pain. While the transdermal delivery of fentanyl is deemed safe and effective in alleviating moderate to severe chronic pain, 1 there have been several reported cases of its intentional or unintentional misuse and abuse leading to significant clinical consequences, including death.2 Both the US Food and Drug Administration and the UK Medicines and Healthcare Products Regulatory Agency (MHRA) 3,4 have previously issued drug safety warnings on the use of fentanyl patches. These were in response to investigations of overdoses of fentanyl due to dosing errors, accidental exposure and exposure of the patch to a heat source. We describe an unintentional, lifethreatening overdose of fentanyl from a transdermal patch placed over a five-day old tattoo, which to our knowledge has not been previously reported. Case reportA 56-year-old male was brought by ambulance to the emergency department having been found at home by his friend to be drowsy and cyanosed. His past medical history included type 2 diabetes mellitus, hypertension, bipolar depressive disorder and chronic back pain. Regular medications were aspirin 75 mg mane, atorvastatin 40 mg mane, citalopram 20 mg mane, fentanyl transdermal patch 100 mcg 72 hourly, human insulin 16 units mane and 14 units nocte, metformin 1G bd and sodium valproate 500 mg mane and 1 g nocte. He was also prescribed as required tramadol 100 mg and naproxen 250 mg.On examination there was a patent airway, respiratory rate of 12 breaths per minute, peripheral oxygen saturations of 92% breathing room air. Blood pressure was 110/75 mmHg, heart rate of 83 beats/min and temperature 36.7 C. His Glasgow Coma Score was fluctuating between E2 V3 M5 and E3 V5 M6 at best. Pupils were 2 mm bilaterally and reactive to light and capillary blood glucose 11.4 mmol/l. He was also acidotic with a pH of 7.24 and PaCO 2 of 9.03 (BE -0.2 mmol/l, HCO 3 28.6 mmol/l).A collateral history from the patient's friend was obtained: the patient had been completely well the evening before the incident; he had become intermittently confused on the afternoon when she found him and had called for an ambulance as he became increasingly drowsy and blue around the lips. She denied witnessing any seizure-like activity, the use of recreational drugs or deliberate overdose. The patient had a similar presentation to the Emergency Department six months previously, with normal findings on an EEG, CT brain and lumbar puncture. At the time he was found to have mi...