ABSTRACT Veterinary nurses have legal and professional responsibilities to maintain accurate controlled drug records . Recording wastage from needle / syringe dead space contributes to accurate record keeping , but only if the volumes recorded are accurate . This study investigated the volume of dead space present in needle / syringe combinations to determine whether recommendations to use a standard wastage volume ( 0.05 ml ) are appropriate .
Combinations of 1 – 20 ml syringes and 21 / 23 / 25G needles were used to draw up sterile water for injection . Syringes were filled to 10 % and 100 % of the measured syringe volume , and the water in the injection bottle was weighed before and after withdrawing each volume , to calculate the total volume of water removed . The volume withdrawn into the syringe ( e . g . 1 ml ) was subtracted from the total volume of water withdrawn from the bottle ( e . g . 1.11 ml ) to determine the volume in the needle / syringe dead space . Ten replicates of each needle / syringe combination were measured , and the effect of needle size , syringe size and syringe fill on dead-space volume were explored .
Needle size was found to have a significant effect on dead-space volume for the 1 ml syringe ( p < 0.001 ) but not for other syringe sizes . Syringe size had a significant effect on dead-space volume ( p < 0.001 ), but there was no significant difference between 5 ml , 10 ml or 20 ml syringe discard volumes ( p > 0.05 ). Syringe fill had no effect on dead-space volume ( p = 0.488 ). The median combined needle / syringe dead space for a 1 ml syringe with a 23 / 25G needle was 0.08 ml ; for a 1 ml syringe with a 21G needle it was 0.11 ml ; for a 3 ml syringe with a 21 – 25G needle it was 0.16 ml ; and for 5 – 20 ml syringes with 21 – 25G needles it was 0.19 ml .
In conclusion , continued use of 0.05 ml for recording dead-space wastage cannot be recommended ; using syringe size-dependent volumes may improve controlled drug record accuracy .
Keywords syringe , dead space , controlled , drug , record keeping , pharmaceutical , waste
Introduction
Controlled drugs ( CDs ) are regularly used in veterinary medicine for analgesia and anaesthesia . The use of CDs within veterinary medicine raises legal , professional and ethical responsibilities for veterinary surgeons ( VSs ) and veterinary nurses ( VNs ) due to the potential misuse of CDs within the profession and the wider population .
Diversion is defined as the transfer of a prescribed drug from the individual to whom it is prescribed to another person , either for illicit use or for sale [ 1 ] . Despite stringent protocols in place regarding CDs , the Care Quality Commission reported that diversion of lowerscheduled CDs in the UK is concerning and methods of diversion are becoming increasingly sophisticated [ 1 ] .
The Misuse of Drugs Regulation 2001 and The Veterinary Medicines Regulation 2013 control all aspects of CD usage , including administration , record keeping and destruction . Regulations require anyone who supplies or purchases Schedule 2 CDs to maintain a controlled drugs register ( CDR ). Any discrepancies must be investigated by a senior VS and may need to be reported to the local police or controlled drug liaison officer [ 6 ] . A discrepancy occurs when the tally in the CDR does not correspond to the amount of stock in the practice . Discrepancies are caused by various situations , some of which are inevitable , such as losses from multidose drug bottles due to needle and syringe dead space ( Figure 1 ) and perished bungs [ 7 ] .
The National Institute on Drug Abuse has announced an opioid overdose crisis , stating that over 100,000 people in the USA died in incidents involving opioids in 2021 [ 2 ] . Current statistics state that more than 130 people are dying daily as a result of overdosing on opioids , and the opioid crisis is impacting veterinary access to CDs for patient care in the USA [ 3 ] .
A survey of US veterinary professionals found that 44 % were aware of opioid misuse by either clients or staff members , and 13 % were aware of animals being intentionally made ill or injured to obtain opioid prescriptions [ 4 ] . While an opioid abuse crisis is not currently reported in the UK , over 16,500 opioid-related deaths were reported in 2010 , and this number was estimated to double by 2022 [ 5 ] .
Figure 1 . The dead-space volume created by the syringe hub ( left ) and the needle body and hub ( middle ). When combined , the liquid remaining within the syringe hub and needle body create a combined needle / syringe dead-space volume ( right ).
Volume 38 ( 2 ) • April 2023
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