Presentation on theme: "SCH Journal Club Lucy Hinds 29 th January 2013. Clinical case You are looking after a 28/40 baby on the neonatal unit. After 3 days on CPAP, she develops."— Presentation transcript:
Clinical case You are looking after a 28/40 baby on the neonatal unit. After 3 days on CPAP, she develops apnoeas and temperature instability. The consultant requests a partial septic screen. What is the best method of taking a sample for blood culture to minimise the risk of contamination?
Current practice No specific guideline Jessop Wing induction teaches: –Clean skin with 2% chlorhexidine –Use either venepuncture or insert a new cannula to take sample of blood for culture –Clean top of the culture bottle –Change needle before inoculating the bottle
Structured clinical question Is there an ideal way to collect blood cultures from neonates to prevent contamination? PICO Outcome Proportion of contaminated blood cultures Compariso n Sample taken from umbilical catheter/ arterial or venous stab Interventio n Sample taken from peripheral cannula at time of insertion Population Neonates requiring blood sample for culture
Why does it matter? Blood culture is diagnostic gold-standard for septicaemia Positive results difficult to interpret due to sample contamination Exposes patients to unnecessary investigations and treatments Increases health care costs Method of collection influences likelihood of contamination
Relationship between blood culture collection method and proportion of contaminated cultures in neonates McLaughlin, L. et al 2013 Journal of Paediatrics & Child Health (doi:10.1111/jpc.12088)
Aims To determine whether the proportion of contaminated cultures varies according to the method of blood collection Preferred methods Arterial puncture Venous puncture Umbilical catheter at time of insertion Non-preferred methods Peripheral arterial or venous cannula at time of insertion
Methods Prospective data collection over 12 month period (2010) All blood cultures taken in NICU/SCBU Proforma completed Medical record number Method of sample collection –Missing proformas completed retrospectively Image removed for copyright reasons
Difference between proportion of cultures contaminated after collection via peripheral arterial/venous puncture (11.5%) and proportion collected via peripheral arterial/venous cannulae at time of insertion (2.1%) was statistically significant (p=0.03)
Limitations Not specified whether culture taken for suspected early- onset or late-onset sepsis Likelihood of positive culture may be greater in late-onset than early onset septicaemia Inability to control for Volume of blood collected Number of skin breaks required Adherence to aseptic technique Level of experience of blood collector Potential bias Staff aware that study underway
Using the GATE frame 1064 Participants Non-preferred method 694 (65.2%) Present Absent Intervention Outcome Expert opinion Comparison Significant difference when comparing arterial/venous puncture AND peripheral cannula at time of insertion Preferred method 275 (25.4%) Unknown 96 (9%) 4.1% 2.4% NO SIGNIFICANT DIFFERENCE
Conclusion Blood cultures taken via peripheral cannula at time of insertion are less likely to be contaminated than cultures taken via separate vascular puncture
Application Will the results of the study help locally? Apply specifically to neonatal population E.g. umbilical catheters Could be extrapolated to older children Highlights important issue Method of collection influences likelihood of blood culture contamination NB – ‘preferred method’ not always best option!
Discussion Local data Total SCH blood cultures received in 2012 3890 Positive 369 (9.5%) Staph. aureus 24 (all fluclox sensitive) Number of probable contaminated specimens (CAV) ~ 60 (actually 31 in six months) 60/3890 = 1.5% Difficult to introduce guideline for best method of collection due to differences in e.g. ED, M3, surgical wards OK to use alcohol wipe for peripheral sample/chlorhexidine for centrally accessed sample