The echocardiogram images ( Figures 4 and 5 ) showed that the patient had a structurally normal heart with chamber dimensions and wall thickness within normal limits . There was mild mitral regurgitation but no evidence of outflow tract obstruction . Myocardial function was well preserved , with normal indices of systolic and diastolic function . No arrhythmia was recorded .
care was taken to ensure the cuff was the correct size for the patient , which is suggested to be 30 % of the limb circumference in feline patients [ 8 ] , and all the readings were taken from the same limb .
In line with the hospital ' s protocol , all patients are graded using the American Society of Anesthesiologists ( ASA ) physical status classification system as part of their preoperative examination . This allows the team to recognise the classification and prepare an anaesthesia plan accordingly . The patient was given a score of ASA III , due to the severe systemic disease and compromised nature of her condition , thereby recognising her as a moderate anaesthesia risk ( Table 3 ).
Table 3 . American Society of Anasthesiologists physical status classification system [ 10 ] .
Figure 4 . A still image captured during the patient ' s echocardiogram , which shows a structurally normal heart .
ASA grade ASA I
ASA II
ASA III
ASA IV
ASA V
Definition
Normal , healthy animal , no underlying disease ( elective procedure )
Slight risk , minor disease present ( healthy patient that needs a procedure )
Moderate risk , obvious disease present ( moderate systemic disease )
High risk , significant compromise by disease ( pre-existing disease or severe disturbances )
Extreme risk , moribund ( life-threatening systemic disease )
Premedication and induction
Figure 5 . A still image captured during the patient ' s echocardiogram , which shows a structurally normal heart .
Blood pressure was measured using an oscillometric device . Although some evidence suggests that this method is less accurate in patients weighing less than 5 kg than direct arterial blood pressure measurement [ 8 ] , it requires less technical skill than invasive blood pressure monitoring , which requires arterial catheterisation . Furthermore , this method allows minimal handling of the patient and helps prevent excessive stress , which could alter the results . To ensure this reading was as accurate as possible , an average was taken from a minimum of three consecutive readings . Current research suggests that five to seven consecutive and consistent readings should be taken , with the first reading being discarded and then an average taken from the remaining readings [ 9 ] . In addition ,
The anaesthetist prescribed methadone 0.2 mg / kg IV as a premedication , which provided mild sedative effects . In patients with significant intracranial disease , opioids alone provide suitable sedation while maintaining cerebral blood flow and avoiding the negative effects of bolus sedatives , such as cardiovascular and respiratory depression [ 4 ] . The patient was preoxygenated via mask following premedication to ensure she received adequate oxygenation during induction and intubation .
Anaesthesia was induced with a combination of alfaxalone ( to effect ) and midazolam 0.2 mg / kg IV . Alfaxalone maintains better cardiovascular function compared with propofol , as it increases the heart rate following vasodilation , which does not occur with propofol . Furthermore , the patient had been induced with propofol the previous day for an MRI . Studies have shown that repeated doses of propofol in cats can have a cumulative effect , causing the formation of Heinz bodies ( cellular inclusions in red blood cells that consist of damaged aggregated haemoglobin ) and associated haemolytic anaemia [ 11 ] .
40 Veterinary Nursing Journal