Plus-Hex CLINICAL
Table 3 . Stages of hypovolaemia and associated clinical signs ( Boag , 2012 ). CRT , Capillary refill time ; MM = mucous membranes . |
Clinical parameter |
Mild hypovolaemia |
Moderate hypovolaemia |
Severe hypovolaemia |
Heart rate |
130 – 150 bpm |
150 – 170 bpm |
170 – 220 bpm |
MM colour |
Normal |
Pale pink |
Grey / muddy |
CRT |
Rapid < 1 second |
1 – 2 seconds |
> 2 seconds or absent |
Pulse amplitude |
Increased |
Mild to |
|
|
moderately decreased |
Severely decreased
Pulse duration Mildly reduced Moderately reduced Severely reduced Metatarsal pulse Easily palpable Just palpable Absent
many clinicians avoid acidic unbuffered fluids , opting instead for a balanced buffered isotonic solution – such as Plasma-Lyte or lactated ringer ' s solution ( Hartmann ' s ) – to limit the potential for the development of hyperchloraemic metabolic acidosis ( Skelly , 2018 ). Boag ( 2012 ) recommends that the fluid type chosen should have a sodium concentration close to the patient ' s serum sodium , to avoid rapid changes in their serum sodium concentration .
Should the patient present with severe hyponatraemia , and is started on 0.9 % sodium chloride , the patient should be transitioned to a more balanced solution after 24 hours of therapy ( Battaglia & Steele , 2016 ). Lactated ringer ' s solution may also be more beneficial in patients where the blood pH is extremely acidic , as 0.9 % saline can contribute to acidosis through a dilution effect ( Battaglia & Steele , 2016 ; Skelly , 2018 ). A general disadvantage of long-term use of isotonic fluid therapy is the increased chance of hypokalaemia . However , due to the condition , this will most likely be an abnormality in need of correction anyway ( Aldridge & O ' Dwyer , 2013 ).
It is recommended to begin insulin treatment 4 – 6 hours after starting fluid therapy , to ensure the hypovolaemia is being corrected ( Battaglia & Steele , 2016 ). The clinical symptoms of stages of hypovolaemia can be seen in Table 3 . Insulin therapy is the cornerstone of treatment , as it allows glucose to be taken up by cells for metabolism and prevents further lipolysis from adding to the ketone burden and promotes ketone metabolism ( Skelly , 2018 ).
There are three types of insulin that can be administered to a diabetic patient : soluble ( neutral ) insulin ( shortterm use ), lente insulin ( medium-acting use ) and protamine zinc insulin ( long-acting , most commonly used on stable long-term diabetic patients ). There are two methods of insulin treatment in a DKA patient : intravenous constant-rate infusion ( CRI ) and shortacting single injections . Short-acting injections can be given subcutaneously or intramuscularly for quicker treatment reactions .
A CRI is the constant delivery of any intravenous medication that can be adjusted whenever necessary , according to clinical symptoms ( Gear & Mathie 2011 ). Insulin CRIs are administered using a neutral insulin to allow for an instant change of rate if necessary . This can be given at a rate of 0.05 – 0.5 IU / kg / hour ( Battaglia & Steele , 2016 ). A CRI is appropriate in most cases of DKA but is predominantly required in moderate to severe cases . With a patient that is showing mild clinical signs , single injections may be sufficient to manage the case ( Skelly , 2018 ).
For accuracy , the insulin CRI should be given using a separate fluid bag and attached to a drip pump , to allow for changes of the CRI rate without having to change the rate of fluids being used for rehydration .
It should be noted that , prior to administration , 50 ml of the insulin fluid solution should be run through the giving set , as insulin binds to the tubing and the syringe . The solution creates a coating that facilitates successful administration ( VetsNow , 2013 ).
The use of a CRI requires at least one fluid pump , so the choice to use this method will need to be in accordance with equipment availability , depending on the resources of the clinic ( Battaglia & Steele , 2016 ).
Another insulin protocol involves injecting the patient intramuscularly with neutral insulin ( Skelly , 2018 ). The initial dose is given at 0.2 IU / kg and , following hourly blood-glucose measurements , further 0.1 IU / kg doses are administered until blood glucose normalises ( VetsNow , 2013 ). Once the blood glucose has normalised and the patient no longer shows signs of ketosis , longer-acting insulin can be administered subcutaneously ( VetsNow , 2013 ).
Depending on the stage of ketosis , this method should be carefully considered as it involves the repeated injection of the patient , alongside repeated blood taking for glucose measurements . It should also be considered that giving any injection intramuscularly has a delayed acting time of 10 – 30 minutes ( Battaglia & Steele , 2016 ).
Volume 37 ( 4 ) • September 2022
17