Peripheral line dead space: an unrecognised phenomenon?

Abstract

Objective: To determine if peripheral intravenous cannula dead space is taken into account when setting up intravenous infusions (in particular nitrate infusions) in the emergency department. Method: A postal survey of UK emergency departments. Results: Of the 143 (58%) of UK departments who responded, only 15% reported priming the cannula before commencing the nitrate infusion. Conclusions: Knowledge of peripheral intravenous cannula dead space in UK emergency departments is very poor and, as a result, there is probably significant widespread under treatment of patients in severe cardiogenic pulmonary oedema. Departments should amend their treatment guidelines to take account of peripheral cannula dead space I ntravenous infusions and bolus doses of drugs are commonly used in emergency medicine. Whereas bolus drugs are nearly always followed with a flush to eradicate residual drugs in the cannula, the personal experience of both the authors was that the lines used to give nitrate infusions are rarely (if ever) primed with the relevant medication in order to take account of their ''dead space''. A current (at time of writing) national trial (the 3CPO trial) makes no mention in its treatment guidelines of priming the peripheral cannula when setting up a nitrate infusion.1 Indeed, its guidelines suggest commencing an infusion at 0.6 mg/h. If a large peripheral (Orange (14G)) cannula was being used this would mean a delay (presuming an infusion concentration of 1 mg/ml) of up to 30 min before any nitrate enters the circulation. If (perhaps more commonly) a green (18G) cannula was being used there would be still be a delay of approximately 20 min. We designed a questionnaire study to look at the current treatment of left ventricular failure/ cardiogenic pulmonary oedema. As part of that questionnaire we asked if intravenous nitrates were routinely used and if cannulas were routinely primed prior to commencing intravenous nitrate infusions.

Residual anaesthesia drugs in intravenous lines – a silent threat?

“…The deadspace of intravenous cannulae ranges from 0.1 ml to 0.3 ml, depending on the manufacturer and the size of the cannula . The deadspace of tunnelled lines is much greater: a 7‐Fr Hickman ® line has a deadpsace of 0.8 ml and a 6‐Fr Portacath ® a deadspace of 1.2 ml, equating to 40–60 mg suxamethonium (50 mg.ml −1 ) or 8–12 mg atracurium (10 mg.ml −1 ) . In our hospital, 10‐cm extensions are often added to intravenous cannulae, particularly when a cannula without an injection port has been used, which increases the measured deadspace by > 1.5 ml.…”

Medication Errors in Cardiopulmonary Arrest and Code-Related Situations

“…26 Central catheters may contain up to 0.5 mL of dead space, which may be problematic for medications with low-volume infusion rates. 26 This issue may apply to medications given via non-free-flowing or longer catheters.…”

“…26 Central catheters may contain up to 0.5 mL of dead space, which may be problematic for medications with low-volume infusion rates. 26 This issue may apply to medications given via non-free-flowing or longer catheters. In addition to fully priming infusion catheters before administration of the infusion is started, common infusions given during codes should be given into free-flowing catheters or directly into the most proximal port to allow for quick delivery.…”

Essential Elements of the Native Glucoregulatory System, Which, If Appreciated, May Help Improve the Function of Glucose Controllers in the Intensive Care Unit Setting

“…Several studies have shown that both the dead space volume of the intravenous catheter and the carrier rate are important with regards to achieving a steady state. [80][81][82][83] The optimal setup would infuse insulin via the peripheral venous catheter or central venous catheter lumen with the smallest dead space volume, while at the same time fixing the carrier solution rate at a minimum of 20 ml/h. In order to minimize the effect of dead space, the insulin infusion line should be connected to the carrier solution line in a position as close to the intravenous catheter as is physically possible.…”