The Oxford English Dictionary defines hypothermia as ‘ the condition of having a body temperature substantially below the normal ’.
The purpose of this report was to highlight inadequate patient warming during routine diagnostic imaging and suggest interventions to prevent patients undergoing radiographs from potentially becoming hypothermic .
Radiographs should only be taken where there is a definite clinical justification [ 1 ] . In order to achieve diagnostic images of the stifle , ‘ chemical restraint should be used where appropriate to achieve good positioning , patient comfort and compliance ’ [ 2 ] . It is important that the patient remains completely still during radiography , as this prevents movement blur . A poor radiographic technique can lead to misdiagnosis and can result in repeated exposures , thereby compromising radiation safety [ 3 ] and extending anaesthesia duration .
Hypothermia is a common problem seen in small animal anaesthesia [ 4 ] but general anaesthesia is necessary ( for the reasons mentioned above ) when it comes to radiographic diagnostic imaging . A canine patient ' s temperature should be in the range 38 – 39.2 ° C [ 5 ] .
Methodology
All patients undergoing sedation or general anaesthesia are assigned a monitoring chart , whereby clinical measurements are taken and recorded as standard practice throughout the patient ' s stay . The audit included patients admitted into the practice for diagnostic imaging of stifles only , over a 3-month period . The temperatures were collated on a separate recording chart , removing all confidential client details .
Data were collected from 14 canine patients admitted for further radiographic investigation of pelvic limb lameness with a potential cruciate ligament injury .
They were all deemed to be in good health on clinical examination , with no other medical conditions .
All patients had a rectal temperature taken at the time of admission ( Figure 1 ). This would be the target body temperature to be maintained during the procedure and on recovery from anaesthesia . Rectal temperature is commonly taken . It is easy to perform , relatively safe [ 4 ] and easily accessible in practice . However , it provides a more peripheral temperature .
All patients for this audit were over 20 kg in weight and received a premedicant of acepromazine ( AceSedate , Jurox ) 0.03 mg / kg and buprenorphine ( Buprelieve , Jurox ) 20 µ g / kg via epaxial muscle injection . All patients were anaesthetised via an intravenous cannula , using alfaxalone ( Alfaxan , Jurox ) 2 mg / kg to effect . All patients were intubated and anaesthesia was maintained with sevoflurane ( SevoFlo , Abbott ) via a rebreathing circle circuit .
Patients undergoing radiographic procedures are anaesthetised in the imaging room and no patient transportation occurs . This is the current protocol for the patients undergoing this procedure at this practice .
The duration of each patient ' s anaesthetic was measured in minutes , from tracheal intubation to tracheal extubation . The number of exposures taken was also noted for the purposes of this audit .
A variety of positioning aids are used to get optimal positioning for the image , including foam wedges , limb ties , fibreglass troughs and white medical tape [ 2 ] . The aids are of varying radio-opacity , so not all are suitable to be placed on or around the patient during exposure of the area of interest . This means they can potentially dominate contact with the patient ' s body in order to obtain the optimal position . This can limit the contact between the patient ' s body and heating aids , reducing their efficacy in maintaining normothermia .
Figure 1 . Patient temperature comparison .
Volume 38 ( 1 ) • February 2023
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