Of the patients that underwent an anaesthetic of 20 minutes ' duration , 64 % had an average temperature loss of 0.9 ° C . Of the patients that underwent an anaesthetic of longer than 20 minutes due to additional radiographs being taken , 36 % experienced an average temperature loss of 1.3 ° C .
Discussion and reflection
Figure 2 ( opposite page ) highlights the incidence of greater anaesthetic length with an increased number of exposures . This can be seen with patient numbers 4 and 11 . These cases were overseen by an inexperienced technician , so additional exposures were required due to inadequate positioning . Patient 4 experienced a temperature reduction of 1.5 ° C . Patient 11 experienced a temperature reduction of 1.9 ° C .
According to Tennant [ 9 ] : ‘ It has generally been accepted that hypothermia starts at a core temperature of < 36 ° C for dogs ’. None of the patients in this audit had a body temperature of less than 36 ° C at any point in the process , as seen in Figure 1 .
There was a 100 % overall incidence of a decreased body temperature during orthogonal views of the stifle , as seen in Figure 2 . None of the patients in this audit had a temperature of less than 36 ° C , so they were not considered to be clinically hypothermic .
Positioning the patients for these views to reduce the anaesthetic time will vary according to the technician ' s expertise and experience . The pace at which these views can be taken , with adequate diagnostic results , should be considered to prevent a reduction in body temperature . The technician also needs to limit the number of exposures taken in practice , according to Ionising Radiation Regulations 2017 ( IRR17 ). This is best achieved if the patient is under general anaesthesia , fully compliant and positioning is eased with as much of the patient ' s anatomy as visible as possible .
Holden [ 10 ] states : ‘ Some degree of heat-loss should be anticipated in all anaesthetised patients ’. However , this heat loss can be exacerbated by the way in which patients are positioned and repeatedly repositioned during radiographical procedures [ 11 ] .
Radiography ‘ can be a time when patients will lose body heat very quickly , through laying on a lead-lined x-ray table ... [ It is important ] to not accelerate heat loss ’ [ 11 ] . Therefore , the provision of a heat source should be considered for radiography procedures .
The way in which this audit was conducted did not interfere with the usual working environment , nor did it affect the cooperating staff , because temperature monitoring is routine for all procedures and all patients within the practice . The routine taking and recording of patients ' temperatures meant the audit was undemanding as the information was readily accessible .
The audit revealed the effect of prolonged anaesthesia times and evidence of a reduction in body temperature , as seen in Figure 2 . However , the main source of the heat loss is due to inadequate patient warming during the procedure , as the rate of heat loss increases immediately after induction and during the first 20 minutes of anaesthesia when the heat is redistributed from the core to the periphery [ 12 ] .
A future audit of patient temperatures could be carried out once it is routine for radiography patients to receive an adequate heat source and appropriate warming .
Reasons for heat loss during this procedure
• Anaesthetist and technician unable to keep fleece / foil / bubble wrap blankets in place for prolonged periods due to regular repositioning of the patient to gain orthogonal views
• Anaesthetist and technician unable to place enough warming barriers between the patient and the radiography table without altering the patient ' s anatomy , making images undiagnostic
• Positioning aids ( e . g . sandbags , troughs and wedges ) are cold to the touch and do not provide a source of heat
• Radiography plates are cold to the touch and do not provide a source of heat
• Prolonged anaesthesia time due to repeat positioning to obtain a diagnostic image
Planned intervention
The practice has not routinely practised adequate patient warming during routine diagnostic radiography , as heating aids and blankets have been the cause of inadequate positioning by altering the anatomy of the patient . Heat pads were badly positioned , either interfering with the position of the radiography plate or not making contact with the patient . However , due to an increasing number of orthopaedic preoperative radiographs being taken in practice in recent times , the reduction in body temperature needs to be addressed and patient-warming interventions need to be investigated and implemented .
This audit has highlighted the importance of patient warming during routine radiographic surveys as significant heat loss can potentially cause health issues if core temperature reduces and is not reversed . Holden [ 10 ] states : ‘ hypothermia during general anaesthesia can slow down the metabolism of drugs and affect blood clotting abilities , increasing the risk of haemorrhage and delay wound healing ’. These patients are likely to return to the practice for orthopaedic surgery , so it is important that any medical disturbances are not
Volume 38 ( 1 ) • February 2023
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