12 Jan 2023
Emma Gerrard
Job Title
Image © yavdat / Adobe Stock
Veterinary nurses are often heavily involved in anaesthesia, participating in pre-anaesthetic assessments, premedication, induction, monitoring and observations during recovery of the patient. An efficient and informed nursing team plays a crucial role in patient preparation, from gaining owner consent through to discharge.
This article aims to provide a brief overview on the phases of perioperative care.
Keywords: perioperative, pre-anaesthetic, anaesthesia, recovery, surgical
The perioperative period describes the duration of a patient’s surgical procedure; this includes admission, anaesthesia, surgery and recovery.
Perioperative generally refers to the three phases of surgery: preoperative, intraoperative, and postoperative (Phillips et al, 2007). However, Mayer and Shepard (2016) stated the perioperative period is when preparations begin to anaesthetise a patient for a surgical, medical or diagnostic imaging procedure until discharge.
The foundation in veterinary practice, and in particular, safe anaesthesia, is preparation.
Assessing the patient and considering the procedure being performed enables anticipation of problems in the peri-anaesthetic period. Its management requires precision, timing and appropriate preparation of the patient, surgical team and equipment.
The correct management of the perioperative period plays a vital role in reducing anaesthetic-related mortality in cats and dogs. Studies by Brodbelt et al (2007; 2008) describe the scientific facts of perioperative risk, and discuss the importance of management of the patient.
Effective communication is imperative to ensure a successful surgical outcome for the patient, owner and surgical team.
Owner compliance is also crucial to a successful outcome; therefore, the patient’s owner must be considered as part of the veterinary team.
Patient preparation begins at the time of admission and clients should be fully informed of all relevant risks associated with the planned procedure, including anaesthesia. The consent form is a legal document that must be completed prior to any procedure requiring sedation and/or anaesthesia. It acts as an admission checklist and should be used to verify the animal’s identity, client’s details and planned surgical procedure. In addition, this discussion should include consented instruction as to what degree of intervention should be performed in the event of a life-threatening emergency, such as a cardiac arrest.
A pre-anaesthetic examination is a vital part of any anaesthetic plan, as it enables the team to identify and address any concurrent disease processes, and anticipates potential complications that may arise as a result of anaesthetising the individual (Sibbald, 2018).
Patients requiring anaesthesia may present with a wide variety of clinical signs and systemic conditions that will require consideration before anaesthesia.
A thorough preoperative assessment must be completed by both the case vet and VN, and should include a complete history, physical exam assessing all body systems and American Society of Anesthesiologists (ASA) grading, along with any additional diagnostics that may improve the safety of anaesthesia for that patient. A baseline temperature, pulse and respiration must also be taken, and recorded on the patient’s anaesthetic chart.
Following the initial assessment, patients should be categorised according to their physical status using the ASA physical status classification system. This scale was developed for use in the human field and is now commonly used in veterinary practice.
Patients of ASA grades one and two are essentially healthy, while those of ASA grades three, four and five are considered sick. The letter “e” following a number denotes “emergency”. The scale has been shown to be predictive of anaesthetic morbidity and mortality in veterinary patients, with sick cats and dogs at a significantly higher risk of death than healthy patients (Brodbelt et al, 2007; 2008).
Pre-anaesthetic diagnostic testing is an adjunct to a detailed patient history and thorough physical examination to aid in the detection of disease; however, its necessity is a controversial topic in both veterinary and human medicine.
Although no doubt exists that pre-anaesthetic biochemical and haematological analyses are valuable for certain patient groups, and those clinically unwell, questions have been raised as to whether they are justified for every patient.
According to Alef et al (2008), a lack of evidence exists to support the use of pre-anaesthetic blood tests in healthy patients that are undergoing routine procedures.
Evidence exists to show pre-anaesthetic blood screening may be beneficial in geriatric patients due to a high proportion of undiagnosed diseases being detected, resulting in a change in management (Joubert, 2007).
In sick patients, pre-anaesthetic blood screening has been associated with decreased risk of death, and ASA grade three to five patients that underwent pre-anaesthetic blood tests were more likely to receive pre-anaesthetic IV fluid therapy (Brodbelt, 2006). Therefore, pre-anaesthetic blood screening is recommended in patients more than eight years old and in clinically unwell patients.
Therefore, the history, physical exam and ASA grading assessments are considered to be more important than blood tests for pre-anaesthetic assessment of healthy patients. However, if these assessments indicate the presence of disease, then pre-anaesthetic bloods are warranted.
Planning and preparation are critical before anaesthetising any patient. The surgical team should take time to discuss the expectations, interventions, equipment and checklists prior to induction. Every patient should have an IV catheter placed to administer fluids and emergency drugs should be calculated pre-emptively.
The correct preparation of preoperative equipment is an essential part of the VN’s role and is crucial to improving patient safety under anaesthesia.
According to Bradbrook (2017), the current recommendation for adult patients is to fast overnight unless the patient presents for emergency treatment. However, starving for any longer than 10 hours increases the acidity of stomach contents and the risk of oesophagitis (Savvas et al, 2009).
The occurrence of gastro-oesophageal reflux (GOR) during the perioperative period has been well documented in dogs and cats, with occurrence rates ranging between 17% to 50% (Savvas et al, 2009). A six to eight-hour fast is considered sufficient (Duke-Novakovski et al, 2016).
Dogs and cats aged less than eight weeks or weighing less than 2kg are at greater risk of hypoglycaemia, and should not be fasted for any more than one to two hours (Bednarski et al, 2015).
Rabbits must not be starved prior to general anaesthesia and hay should be available at all times. Harcourt-Brown (2007) suggests pellet and fresh food items can be removed approximately one hour prior to induction to help minimise the presence of residual food particles in the oropharynx, and to decrease stomach volume to reduce pressure on the diaphragm. If assisted feeding is being performed, the final feed should be approximately 30 minutes prior to premedication (Meredith and Lord, 2014).
Safety checklists are an important tool in the perioperative period and are paramount in maximising successful patient outcomes.
Checklists are designed to ensure effective communication and improve collaboration on the delivery of patient care, and they should be used to identify patient risks prior to surgery so strategies can be discussed and implemented to minimise any risk to patients, and staff (Mayer and Shepard, 2016).
Safety checklists are a list of actionable tasks that are crucial to the performance of a process and the tasks listed must be completed before moving on to the next stage.
The use of surgical safety checklists should involve all members of the team to ensure engagement and compliance.
The use of checklists involves the confirmation that key information is correct, and ensures equipment is available and has been properly prepared prior to use.
The ASA developed a safety checklist with the aim to increase awareness and reduce human error to improve patient safety in anaesthesia. This checklist helps to ensure the anaesthetic machine and breathing system are in good working order, and safe to use prior to induction of the patient.
The use of anaesthetic safety checklists can improve patient safety, ensure critical steps have been performed prior to anaesthesia and improve communication and collaboration between team members (McMillan, 2014).
Anaesthetic equipment is considered “life-critical” because the safety of patients can be adversely affected if equipment is functioning suboptimally or used incorrectly.
Checking equipment will help to identify and prevent problems caused by technical faults or errors. Therefore, checklists should include the preparation of all equipment and emergency drugs before induction to avoid any delay should a complication occur.
A study by Hofmeister (2013) showed the use of a short peri-anaesthetic checklist significantly reduced the number of incidents, such as medication errors, oesophageal intubation and closed adjustable pressure limiting valves.
The incidence of hospital-acquired infections (HAIs) is growing in companion animals (Deasy, 2013).
Hands are the main pathway of germ transmission and, therefore, hand hygiene is the most important measure to avoid cross-contamination. Studies have shown that regular handwashing significantly reduces the risk of nosocomial infections (World Health Organization, 2009); however, the environment is also a contributing factor.
The principles behind infection control in the surgical environment are to limit contamination of the surgical site with microorganisms from the patient, surgical team, operating theatre and surgical equipment.
Contamination is commonly caused by endogenous sources (the patient’s own microbial flora) or, less commonly, exogenous sources (surgical field contamination, including the surgical team, instruments and equipment).
Therefore, the efficiency of the surgical team in preparing the environment, patient and the standard of practice protocols regarding wound management can directly impact the risk of surgical site infection.
The surgical day should be planned in order of sterility as the cleanliness of the surgical site and area will influence infection control measures required.
Where possible, dirty procedures should not take place in theatre, and patients with known infections such as pseudomonas and MRSA must be scheduled at the end of the surgical list.
Anaesthesia should not be thought to be routine or straight forward. No room for complacency exists in anaesthesia and each patient should have a holistic protocol in place.
According to Smith (1959), “there are no safe anaesthetic agents, there are no safe anaesthetic procedures, there are only safe anaesthetists”. The most appropriate anaesthetic protocol should consider the species and signalment, any concurrent diseases and past responses to anaesthesia.
Other factors such as drug availability, practice capabilities, surgical approach and experience level of the surgeon should also be taken into consideration (Mancinelli, 2018).
The use of pre-anaesthetic medication has been associated with a decreased risk of death, compared to no pre-anaesthetic medication (Brodbelt, 2006).
Good pre-anaesthetic medication reduces patient stress, provides analgesia and reduces anaesthetic agent requirement, which is especially important in sick and elderly patients.
When considering sedative and anaesthetic agents, familiarity with the drugs is more important than the choice of drugs (Brodbelt, 2006), and they should be tailored to each patient and procedure.
While the veterinary surgeon decides the drug protocols, nurses should have a basic understanding of their pharmacology and be able to participate in clinical discussions on protocols.
Perioperative hypothermia is a common problem during the perioperative period and can have detrimental effects on the patient’s physiology, such as impairment of kidney function.
Management of body temperature, including regular monitoring, should begin following premedication as patients begin to become hypothermic following administration of the pre-anaesthetic drugs.
Cats, small dogs and small mammals, as well as neonatal patients, will be more susceptible to hypothermia due to their large surface area to bodyweight ratio, or their reduced muscle mass and body fat.
Senior patients are more susceptible to hypothermia and may have a reduced capacity for drug metabolism, causing prolonged recoveries (Neiger-Aeschbacher, 2007).
Patients with hepatic dysfunction are also prone to hypothermia as the heat that is typically generated from metabolic activity is reduced.
Hypothermia also directly affects how a patient will recover; therefore, temperature management during anaesthesia is crucial.
Brodbelt et al (2008) reported that the recovery times of hypothermic patients were twice as long as normothermic animals and were also less predictable.
According to Steinbacher et al (2010), a direct link in cats exists from their temperature in recovery to the time of extubation, with more hypothermic patients taking longer to show control of their airway and pharyngeal tissue.
Clinical observation and hands-on assessment by a vigilant anaesthetist are essential for safe patient care during the peri-anaesthetic period.
Good monitoring enables anaesthetic complications to be detected and corrected before they become life threatening.
The availability of equipment, such as a capnograph, pulse oximeter, blood pressure monitoring and an electrocardiogram, will greatly improve the quality of anaesthesia. Body temperature monitoring should be included and not overlooked. Patient positioning should be checked regularly during anaesthesia to avoid impairment of respiration and venous return.
The International Association for the Study of Pain (IASP) defines pain as an unpleasant sensory and emotional experience associated with actual, or potential tissue damage, or described in terms of such damage (IASP, 1979).
Analgesia is a key component of well-balanced anaesthesia for all surgical procedures and a pain management plan should be devised for each individual patient. The objective should be to provide effective pre-emptive and multimodal analgesic approach, while taking each phase of the preoperative period into account.
Assessment of pain is complex and multidimensional, and is mostly based on the recognition of behavioural changes in response to pain.
Pain scoring systems should be used to determine whether pain exists, whether analgesia is sufficient and to monitor patient progress in terms of pain management.
A variety of pain scales have been adapted for the use in clinical situations. Their use can facilitate consistency in the team approach, and should be a tool to standardise the interpretation of pain and produce measurable quantitative data for accurate assessment of a patient’s progress.
Recovery is a critical phase of the perioperative period. The recovery phase begins when the anaesthetic gas is turned off and not at the time of extubation.
Patients recovering from anaesthesia require monitoring regularly until their parameters have returned to near baseline.
The Confidential Enquiry into Perioperative Small Animal Fatalities (CEPSAF; Brodbelt, 2006) study demonstrated that the percentage of deaths in recovery is higher than that of premedication, induction and maintenance periods.
The study identified the recovery period as the period of greatest risk during anaesthesia, with most deaths occurring within three hours after the procedure.
While many complications can occur throughout anaesthesia, most anaesthetic-associated deaths occur during recovery – especially in the first three hours. In total, 47% of canine anaesthesia mortalities and 60% of feline anaesthesia moralities have been reported to have occurred in the postoperative period (Broadbelt et al, 2008).
The main objectives of adequate recovery care are to continue to critically monitor, evaluate and stabilise the patient postoperatively (Mayer and Shepard, 2016).
The patient’s airway must be kept patent to allow adequate ventilation, and positioning should, therefore, be constantly monitored. The patient should be positioned depending on the situation and oxygen therapy provided, if required.
The patient should be visually assessed checking for the return of protective reflexes and consciousness. After an airway has been re-established, all parameters must be monitored during the recovery phase, and compared to baseline results obtained preoperatively and those recorded while under anaesthesia. This means that trends can be noted and problems can be recognised so early intervention can be performed.
Asepsis must continue after the patient leaves theatre. Wounds should be covered with a sterile dressing before the patient leaves theatre, and should be changed as soon as it becomes soiled or contaminated by strike-through.
The dressing should remain in place for at least six to 12 hours postoperatively, allowing the wound to seal and prevent bacterial contamination of the blood clot between the skin edges in the early time period (Anderson, 2012).
This dressing will protect the wound from self-induced trauma, urine and faeces – especially during the recovery period and contamination to or from the environment.
The patient’s environment must be maintained and cleaned to a high standard, with clean, dry bedding provided.
Once stable, patients should receive nutritional support – this is particularly important for immature or geriatric animals, which may have low glycogen stores.
Early postoperative nutrition can reduce recovery time, decrease morbidity and mortality, and mimimise the risk of wound breakdown and infection (Hoad, 2013).
Discharge of patients that have undergone anaesthesia should only occur after the patient is responsive, comfortable and ambulatory.
Providing good quality postoperative advice can make a significant difference to the speed and smoothness of a patient’s recovery.
VNs are often involved with discharging cases – especially those that have undergone elective or routine procedures – and so will need to make clear recommendations to the client regarding all aspects of postoperative care.
Both verbal and written postoperative nursing care plans and written notes can aid compliance. A postoperative check appointment must be made prior to discharging the patient.
A thorough understanding of the preoperative phases are essential when caring for patients.
Every patient should be assessed holistically, and nursing care planned and implemented accordingly, taking into account case-specific needs during a patient’s perioperative journey.
