Introduction CONTINOUS HEPARIN INFUSIONS require monitoring aPTT values. Blood samples can be collected from a central venous access device (CVAD) if present or from a peripheral vein (PV). If heparin is infusing through a CVAD, how should aPTTs be collected? • Peripheral specimen required/desired? • From CVAD acceptable? Desired port? • Turn off infusion? How long? Flush first? Waste amount? Comparison of aPTT values from venipuncture and central venous access device specimens in hospitalized adult patients receiving continuous heparin infusions Mary Sue Dailey APN-CNS, Fortunata Dabu, RN, BSN, Sue Durkin, APN- CNS, Barbara Kohn, MTRN, BSN, Barbara Berger, PhD, RN Recommendations Results Relevant Literature Venipuncture vs Heparinized Arterial Line •Alzetani (2004)( n=49) Arterial aPTT unreliable •Heap ( 1997) (n=79) Arterial aPTT valid 96% of time Venipuncture vs Heparinized CVAD without continuous heparin infusion •Humphries and Baldwin (2012)( n=30) Power =.71 •0.99 correlation between PICC and VP specimens •Rondina (2007) (n= 41) •No significant difference between CVAD and VP specimen •Hinds (2002) (n=53 pediatric patients with tunneled CVAD ) •Tunneled CVAD results inaccurate but as discard volume increased paired results closer ( tested 6,9,12mL discards) Venipuncture vs CVAD-with continuous heparin infusion •Bellmunt. P, et al. (2000) (n=74) •Significant difference in aPTT between CVAD and venipuncture specimens with either a 10 or 20mL discard -- the difference was slightly lower with 20mL discard (10.6 sec aPTT difference with 20mL discard vs. 12.7 sec with 10mL discard) . Discrepancies at Start of Study Policies Lab: Turn off infusion •Waste depends on dead space – 5-12mL Nursing: No mention of stopping infusion first •No mention of “desired port” •Waste first 6 mL Professional Standards -- Infusion Nursing Society (INS) (2006) Manufacturer’s Guidelines . Study Design & Methods Paired blood specimens (CVAD & peripheral venipuncture) from 74 patients receiving a continuous heparin infusion through a CVAD. Specimens were collected simultaneously by a research RN and a phlebotomist • Protocol: turn off infusions for at least 1 minutes, flush line with 10 ml., wait 1 minute, draw and discard 10ml, then draw aPTT specimen. • Power = .80 with alpha=.05 Actual RN practice at Good Samaritan Hospital 134 respondents completed an online survey in 2009 •82% flushed prior to obtaining sample •50% wasted 10 mL •56% collected the coagulation specimen first •94% stopped the infusion Purpose Is there a clinically significant difference between the aPTT results from a CVAD specimen and a peripheral venipuncture (VP) when the patient is receiving continuous heparin through the CVAD? Collect aPTT specimen from peripheral venipuncture if possible If CVAD specimen necessary: • Collect from port without a heparin infusion • Follow INS guidelines-turn heparin off 5 minutes prior to specimen collection Designate port for heparin infusion- proximal port is preferred as blood flow diffuses drug into circulation. Thanks to data collectors: Colleen O’Leary, APN, Karen Calimlim, RN, Carrie Bauman, RN, Barbara Gulczynski,APN, Karen Hagemaster, RN, Joy Kennedy, RN, Cindy Zaletel, APN Discussion Sample Characteristics Age: mean = 67.5 yrs (SD 13.8), median = 70, range 26 to 94 Sex: 36 females (49%), 38 males (51%) Race: 63 white (85%), 11 other (15%) PTT values between CVAD & peripheral specimens were significantly different if sample was drawn from heparin infusion port; there was no difference between peripheral & CVAD specimens if sample was drawn from port either proximal or distal to heparin infusion port. For nurses, compatibility of infusates was of greater concern than which port of the CVAD was used for the infusion, resulting in no standard approach to “which drug should be infused where.” After study began, the INS (2011) issued standards recommending coagulation studies not be drawn from lines with any exposure to heparin. Institution policies were recently revised to recommend peripheral specimens for coagulation studies. N=74 Arrow ( TLC) Bard ( PICC) Use proximal port Turn off distal infusions for at least one minute Discard volume varies from priming volume (dead space) to 3-10mL Flush per hospital protocol Waste 2-6 X the priming volume 5mL = 6x the priming volume of all nontunneled PICC variable n mean (SD) Test statistic p-value PTT (seconds) From central line From venipuncture 74 74 82.1 (47.2) 74.0 (42.0) PTT difference (seconds) (CVAD – venipuncture) 74 8.1 (34.6) t 73 = -2.017 .047 PTT difference (seconds) n mean (SD) Test statistic p-value By line type PICC Other central line 55 19 -16.7 (55.0) -5.2 (24.1) t 20.4 = -0.881 .389 By indication DVT / PE Cardiac Other 34 32 8 -2.0 (29.6) -11.9 (35.0) -18.8 (50.7) F 2,71 = 1.099 .339 Additional infusions Heparin only Heparin + fluids Heparin + meds 24 19 25 -5.1 (29.4) 2.7 (25.5) -20.4 (44.7) F 2,65 =2.534 .087 By collection method Syringe Vacutainer 53 21 -7.6 (32.6) -9.4 (40.2) t 72 = 0.205 .838 By additional specimens Yes No 7 67 -27.1 (52.0) -6.1 (32.3) t 72 = 1.538 .128 By time infusion off 1 minute >1 minute 55 19 -11.2 (38.8) 0.8 (15.2) t 72 = -1.307 .196 PTT difference (seconds) by relative position of specimen port to heparin infusion port n mean (SD) Kruskall Wallis test p- value Specimen from heparin port 15 -31.0 (43.8) X 2 2 =13.007 .001 Specimen from a port proximal to heparin port 27 -3.0 (24.7) Specimen from a port distal to heparin port 25 -1.4 (37.3) •Stop infusion •Flush with 3-5 mL saline •Distal lumen preferred •Discard volume = to 1.5-2 times the fill volume of the CVAD PTT difference by relative position of sampling port