The interventions were performed to prevent ventilatorassociated pneumonia , corneal ulcer formation , the development of oral ulcers , glossal swelling and pooling of secretions , and regurgitation in the oral cavity ( Donovan , 2017 ) – as well as preventing urine scalding and decubital ulcer formation ( Donovan , 2017 ). The patient was maintained in a neutral horizontal position on a well-padded orthopaedic mattress , with limbs supported using blankets . If the patient were to have been anaesthetised longer , enteral feeding may have been required .
Oxygen therapy
Following recovery , oxygen supplementation was provided via nasal oxygen prongs , which the patient tolerated well initially . Nasal oxygen prongs are thought to deliver an FiO 2 of 0.4 ( Waddel & King , 2018 ). The patient was positioned in sternal recumbency with the neck extended to improve comfort and aid lung expansion .
The pulse oximetry was used as it is a non-invasive method that is easy to use , cost effective and continual . Pulse oximetry measures the amount of oxygen attached to the haemoglobin ( SpO 2
). However , this value does not have a linear relationship with the PaO 2
( Waddel & King , 2018 ). Haemoglobin should normally be saturated with > 95 % oxygen . However , haemoglobin becomes almost fully saturated at a PaO 2 of 80 mmHg and , at this point , the curve plateaus and , despite a higher
PaO 2
, the SpO 2 cannot be further increased . This curve may be altered in critically ill patients due to alterations in pH , temperature and PCO 2
( Farrell et al ., 2019 ).
On reflection , further arterial blood gas analysis may have been beneficial in the recovery period . A study by Farrell et al ( 2019 ) found that pulse oximetry was not a clinically suitable surrogate for arterial blood gas analysis in dogs that are breathing room air , but was more useful in dogs undergoing mechanical ventilation . In both control groups , the sensitivity of SpO 2 to detect hypoxaemia was poor ( Farrell et al ., 2019 ). Waddel and King ( 2018 ) suggest that any condition where there is a diminished blood flow to tissues , such as hypotension or shock , can affect the accuracy of pulse oximetry .
The patient ’ s SpO 2 overnight was between 93 % and 95 % when receiving oxygen via the nasal prongs . Numerous oxygen tests were performed where the patient was slowly weaned from the oxygen support to see if he could maintain his own oxygenation . Initially , the patient ’ s SpO 2 depleted to 85 % after 5 minutes without oxygen therapy . After 24 hours , the SpO 2 without oxygen supplementation gradually improved to 98 %. At times , there were lower anomalous results that were assumed to be attributable to patient movement as the puppy was becoming very lively and playful .
Medications
The oxygen was humidified using a bubble chamber filled with distilled water , to prevent desiccation of the airways . Waddel and King ( 2018 ) suggest that longterm oxygen therapy can damage the lungs , as the toxic metabolites of oxygen cause inflammation . This was prevented by minimising the FiO 2 used to maintain the patient at a stable level . The patient ’ s respiratory rate , effort , heart rate and pulse rate , mucous membrane colour and capillary refill time were continually observed , while also monitoring arterial blood gases and utilising a pulse oximeter .
Due to the excitable nature of the patient , sedative drugs were used during the treatment to reduce excitability and consequent respiratory distress . Butorphanol ( Torbugesic , Zoetis UK Limited ) at 0.1 mg / kg IV was used as required , alongside acepromazine ( Acecare , Animalcare Limited ) 0.01 mg / kg IV . The patient was maintained in a sedated manner for 24 hours to aid in the tolerance of the nasal prongs and to reduce stress . An important consideration for the use of these sedatives is that neither has a direct reversal agent so constant monitoring in an intensive care unit ( ICU ) is recommended ( Tong & Gonzalez , 2020 ).
Diuretic use in non-cardiogenic oedema is controversial , with limited evidence for its use . During the stabilisation , while initiating ventilation , a single dose of furosemide ( Dimazon , MSD Animal Health ) at 5 mg / kg IV was administered . Studies suggest the use of diuretics can reduce the intravascular volume and modify Starling ’ s equation in favour of intracapillary filtration and oedema resolution ( Louis and Fernandes , 2002 ; Udeshi , Cantie
42 Veterinary Nursing Journal