Papers

Local warming and insertion of peripheral venous cannulas: single blinded prospective randomised controlled trial and single blinded randomised crossover trial

Rainer Lenhardt, assistant professor, ^a Tanja Seybold, resident in anaesthesia, ^b Oliver Kimberger, resident in anaesthesia, ^b Brigitte Stoiser, resident in haematology, ^c Daniel I Sessler, associate dean for research. ^a

^a Outcomes Research Institute and Department of Anaesthesiology, University of Louisville, Louisville, KY 40202 USA, ^b Department of Anaesthesiology, University of Vienna, Vienna A-1090, Austria, ^c Department of Internal Medicine, University of Vienna

Correspondence to: R Lenhardt rainerlenhardt{at}compuserve.com

Objective: To determine whether local warming of the lower arm and hand facilitates peripheral venous cannulation.
Design: Single blinded prospective randomised controlled trial and single blinded randomised crossover trial.
Setting: Neurosurgical unit and haematology ward of university hospital.
Participants: 100 neurosurgical patients and 40 patients with leukaemia who required chemotherapy.
Interventions: Neurosurgical patients' hands and forearms were covered for 15 minutes with a carbon fibre heating mitt. Patients were assigned randomly to active warming at 52°C or passive insulation (heater not activated). The same warming system was used for 10 minutes in patients with leukaemia. They were assigned randomly to active warming or passive insulation on day 1 and given alternative treatment during the subsequent visit.
Main outcome measures: Primary: success rate for insertion of 18 gauge cannula into vein on back of hand. Secondary: time required for successful cannulation.
Results: In neurosurgical patients, it took 36 seconds (95% confidence interval 31 to 40 seconds) to insert a cannula in the active warming group and 62 (50 to 74) seconds in the passive insulation group (P=0.002). Three (6%) first attempts failed in the active warming group compared with 14 (28%) in the passive insulation group (P=0.008). The crossover study in patients with leukaemia showed that insertion time was reduced by 20 seconds (8 to 32, P=0.013) with active warming and that failure rates at first attempt were 6% with warming and 30% with passive insulation (P<0.001).
Conclusions: Local warming facilitates the insertion of peripheral venous cannulas, reducing both time and number of attempts required. This may decrease the time staff spend inserting cannulas, reduce supply costs, and improve patient satisfaction.

What is already known on this topic Insertion of peripheral venous cannulas may be difficult because of severe vasoconstriction Vasoconstriction can be overcome by local heating What this study adds Active local warming facilitates the insertion of peripheral venous cannulas, reducing both the time and number of attempts required Local warming will decrease the amount of time staff spend inserting cannulas, reduce supply costs, and improve patient satisfaction