Anaesthesia

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Fortunately, anaesthetics these days are extremely safe – especially compared to the “bad old days” of ten to twenty years ago, when monitoring equipment was less widely used and anaesthetic agents were less advanced.

All anaesthesia carries risk; there is no escape from that fact, even for us humans! However, the risk is very minor, and adverse anaesthetic reactions are extremely rare, especially in young healthy patients.

Owners of older pets are often concerned about having them undergo anaesthesia. This is where modern anaesthetic agents, monitoring equipment and indeed the skill of the veterinarian come into their own. Anaesthetic risk does increase with age and ill-health, but the risks are very minor nevertheless. We will run through the basic anaesthesia protocol that is normal for most patients, then we will discuss the various extra options that are available for clients that wish to provide additional care to their pets, and especially for aging or ill patients.

 

Standard Quality Protocol:

  • Patients are given a “pre-anaesthesia” sedative injection about half an hour before the operation. At Southernvets we use a combination of Acepromazine and Buprenorphine. Buprenorphine is an opioid analgesic (similar to morphine) that reduces the required dose  – and, therefore, the risks – of the anaesthetic agent required, as well as calming the patient and providing greater pain relief post surgery.
  • When ready for surgery, the patient is “induced” into a state of general anaesthesia using an intravenous agent. There are many different types available. One of the most modern and safe induction agents is Alfaxan, which we use in both cats and dogs. The patient is asleep within five to ten seconds of Alfaxan being administered directly into the vein. Induction agents have a short duration of action; for example, a patient given Alfaxan will be awake again within five minutes. Hence we use this opportunity to place an endotracheal tube in the airway and connect the patient to a flow of oxygen and Isoflurane gas. Gaseous anaesthetics are the safest way to maintain ongoing general anaesthesia for as long as needed, and Isoflurane is one of the most modern of those available. Once surgery is complete, the Isoflurane is turned off and patients awake within five minutes. Having been given the analgesic Buprenorphine prior to surgery, and anti-inflammatory pain relief during the procedure, they awake calmly and comfortably.
  • Throughout anaesthesia, the patient’s ongoing condition is assessed with monitoring equipment. This includes an ap-Alert machine which registers every breath the patient takes, and a Pulse Oximeter which monitors heart rate and blood oxygen levels, enabling anaesthesia to be modified as needed. In times past, gaseous maintenance anaesthesia and monitoring equipment were not commonly employed. These days they are available at most clinics, but if you’re concerned always feel free to ask what the protocol is used for your pet. Not all clinics follow the same protocols.
  • All patients at Southern Animal Health are given Buprenorphine and Metacam pain relief injections to provide the smoothest post-surgical recovery possible. These are not standard across all clinics, so feel welcome to ask what your pet will be given, and how they will be anaesthetised.

The above regime describes very modern and safe anaesthetic practice which ensures very little risk of adverse reactions, even in old and sick patients. There are however, extra precautions that can be added to this regime for concerned clients, and especially for old and sick patients. We will describe these options, then explain the actual advantages of each.

 

Pre-Anaesthetic Blood Screen

A blood test prior to surgery may detect underlying conditions that don’t necessarily cause visible symptoms but can affect an animal’s response to anaesthetic.

 

Intra-Operative Fluids

Intra-operative fluid therapy has a two-fold benefit. Firstly, it helps to counteract the drop in blood pressure that tends to occur during anaesthesia. Maintaining blood pressure reduces this risk factor and can help to protect against potential organ failure in sick and elderly patients. Secondly, young and old patients alike generally experience a better recovery from surgery if they are not in a state of dehydration. It’s amazing how patients that have had fluids are often quite bouncy and active even a few hours after anaesthesia.

 

Propofol Induction Agent

Propofol is offered as a safer induction agent alternative in some clinics, at an extra charge compared to whatever agent is usually used. With the advent of Alfaxan, we believe that the advantages of Propofol are minor, if at all, compared to Alfaxan. Although we do provide Propofol for clients on request, we are unconvinced that this induction agent offers any significant benifits over Alfaxan, which itself is much safer than many of the other commoly used induction agents. We have made it policy at Southernvets to use Alfaxan routinely for all types of patients.

 

Advantages of these extra options

Pre-anaesthetic blood screens: In a young healthy patient, the chance of picking up relevent information is extremely minor. For the extra cost involved, in these cases there is minimal value to be gained. As a patient ages or health deteriorates, then I would advise each individual client on a case-by-case basis whether a blood test should be strongly considered. That said, we are always happy to perform blood testing if a client wants it.

Intra-operative fluids: For young healthy animals, intravenous fluid therapy can make an already extremely safe anaesthesia slightly more safe at best. But more importantly, maintaining hydration allows them a more pleasant recovery – they go home feeling less drowsy. This in itself is a good reason to consider fluids, but if costs are a concern and your veterinary clinician hasn’t specifically recommended them, then you can regard the anaesthetic safety factor as minor.

Propofol induction agent: Usually offered at extra cost as a “safer” alternative to the usual inductaion agent that the clinic uses. We don’t believe this is any safer than Alfaxan which we use as standard in our practice, at no extra charge. Available on request if desired.

 

Botom line

Don’t be scared of anaesthesia to the point that a patient’s health may be more compromised by not performing a surgical procedure. Consider fluids as the main extra, and we as clinicians will advise whether bloods should be considered more strongly, but the choice is still there for you if costs are of no concern.