The Confidential Enquiry into Perioperative Small Animal Fatalities (CEPSAF), is one of the largest prospective studies in veterinary medicine (Brodbelt et al, 2006). In this study Brodbelt et al (2006) examined perioperative small animal fatalities (Figure 1). The authors defined anaesthetic-related deaths as perioperative deaths within 48 hours following termination of the patient's procedure, except where death was due solely to inoperable surgical or pre-existing medical conditions. Blood and Studdert (1988) define the recovery period as the return to normal after general anaesthesia and surgery, including the patient's requirements for close monitoring to ensure that its return to normal is uneventful. The recovery period ends when a full level of consciousness is present and physiological values have normalized (Holden, 1999).
Hall and Clarke (1991) highlighted in their study that 1:434 dogs and 1:340 cats suffered anaesthetic-related deaths in the UK in 1991. Although mortality has slightly improved since Hall and Clarke's initial study, it is an area where veterinary practices may be able to improve their post-operative recovery nursing care. This article will discuss the areas of the recovery period that may be improved to decrease mortality rates in patients and also discuss improvements to nursing care that could be implemented.
Why is the recovery period a risk?
Lack of monitoring
Research into this area highlights a lack of monitoring as the main risk factor in the care of patients in the recovery area (Prosser and McArthur-Rouse, 2007). During the maintenance period animals are monitored regularly with recommendations of basic temperature, pulse and respiration monitoring every 5 minutes (Shmon, 2003). Additional monitoring may include blood pressure monitoring to check for hypotension or hypertension, oxygen saturation monitoring to highlight hypoxia, electrocardiogram observations for irregularities in the patient's heart, continuous capnography monitoring to highlight hypocapnia or hypercapnia and blood gases to check for acidosis. This additional monitoring would be considered vital in the post-operative recovery of critical patients and must be an individual case decision. If this monitoring is not continued into the recovery period then a critical event may be missed. This monitoring may be the responsibility of a specific nurse that is solely responsible for all patients in the recovery area and ideally documents the observations onto a recovery record for each individual patient. However, Adams et al (1998) have discussed the fact that nurses do not work in ways characteristic of three ‘ideal’ types of practice — functional, team, and primary nursing — but are organized on a more complex basis; these are three theoretical ways in which nurses work. Recovery nursing is ideally performed by a single nurse demonstrating primary nursing. Primary nursing benefits the care of the patient in that the complete recovery history is known and critical events are possibly noticed earlier as the nurse is familiar with the patient's expected and recorded observations. If it is necessary that an additional nurse be involved in the care of any patients in the recovery period, then a full post-operative discussion between the nurses who are involved in the postoperative care of the patients should be performed in the form of a ‘change over’ or ‘ward round’. Functional nursing involves a task-oriented approach to patient care involving numerous nurses with specific tasks allocated. Team nursing may be described as a ‘team’ of nurses providing different skills to care for a patient. Ideally primary nursing should be used when nursing patients in the post-operative period. It is also considered a legal requirement that anaesthesia observations are documented (Royal College of Veterinary Surgeons, 2010) and this should ideally be continued until the animal's vital signs are normalized. Documentation of vital signs should be continued during the recovery period and these should be recorded on either an anaesthetic record or a recovery record.
Hypothermia
Hypothermia contributes to a decreased level of consciousness and impairs respiratory and cardiac function. Shivering, a common effect of hypothermia, increases oxygen demand by up to 300% at a time when oxygen delivery to the tissues may be impaired by the cardiopulmonary depressant effects of anaesthesia (Holden, 1999). Animals with respiratory compromise which are hypothermic should receive oxygen supplementation in the recovery period. Any hypothermic animal should be actively warmed in the recovery period and be constantly monitored until its temperature is above 37°C (Hamilton, 2003).
There are a number of methods of warming patients with hypothermia:
Hypoxia
Hypoxia may occur if consciousness is inadequate at extubation causing airway compromise. This is a potential risk in cats where laryngospasm may be a factor. In cats, opinion varies about when to remove the endotracheal tube (ET): either when the cat's ears, tail or limbs begin to twitch or when the swallowing reflex returns (Hamilton, 2003). Delays, however, in removing the tube may lead to irritation or spasm of the larynx. If left too late the cat often bites the ET making it difficult to remove and potentially over stimulating the larynx. In doliocephalic and mesocephalic dogs the ET can be left in until the swallowing reflex has returned, however, in brachycephalic breeds the endotracheal tube may be left in place until the patient will no longer tolerate it (Figure 3). This is to minimize the risk of any upper airway obstruction during the recovery period. The cuff may be left inflated until just prior to extubation to reduce the risk of aspiration of any fluids. The patient will also benefit from being placed in sternal recumbency to allow full expansion of both chest cavities with the head and neck extended with their tongue drawn forward to maintain a patent airway (Welsh, 2003). Intubation equipment should ideally be organized to allow rapid re-intubation if required.
With the benefit of capnography (see below) adequacy of ventilation can be assessed prior to extubation, this would provide information on the patient's expired carbon dioxide (CO2) levels and highlight if the patient became hypocapnic or hypercapnic. If an animal is judged to be hypoventilating at the end of anaesthesia, oxygen delivery should be continued until ventilation has normalized, prior to removal of the ET. Ideally the patient should be provided with additional fresh oxygen for a period after the maintenance gas has been switched off and only be disconnected once oxygen saturation is no less than 95% without oxygen supplement being provided (Welsh, 2003).
Basic patient monitoring
Ideally all animals should be closely monitored (Table 1), including basic monitoring of temperature, pulse and respiration, until they are normal and the patient is able to lift their head. However, every animal must be assessed as an individual with the assessment dependant on the type of procedure performed and the underlying disease. Preparation for all eventualities can have a positive outcome in an emergency and is the hallmark of a good anaesthetist. Those animals that are considered at greater risk can be identified by the anaesthetist using the American Society of Anaesthesiologist (ASA) classification system and a case-specific plan made for their one-to-one care. An example of good preparation would be a brachycephalic dog which has had surgery. The recovery nurse should have all equipment necessary for reintubation of the trachea should respiratory distress occur — this includes ensuring that the intravenous catheter is patent at all times (Prosser and McArthur-Rouse, 2007).
| Observations to be performed | What body system is being monitored |
|---|---|
| Heart rate and rhythm | Cardiovascular |
| Peripheral pulse palpation | Cardiovascular |
| Temperature | Prevent hyperthermia and hypothermia |
| Capillary refill time and mucus membrane colour | Cardiovascular |
| Chest auscultation and respiratory rate | Respiratory system |
| Blood pressure | Cardiovascular |
| Intravenous fluid administration | Cardiovascular support |
| Oxygen saturation | Respiratory system |
| Expired carbon dioxide concentrations | Respiratory system |
| Analgesia requirements | Pain management |
Monitoring: information and uses
Cardiovascular
The cardiovasular system should be monitored by auscultation of the heart along with frequent palpation of a peripheral pulse. Peripheral pulses (i.e. dorsal pedal) should be assessed primarily rather than central pulses (femoral) as these pulses are among the first to alter in character if circulation and hence perfusion becomes compromised (Welsh, 2003); a change in peripheral pulse could indicate that a problem was developing. Capillary refill time is the time required for the mucosal layer, which has been blanched by finger pressure, to return to a normal pink colour. Failure for the colour to return promptly is an indication of peripheral circulatory compromise. Brick red mucosa may indicate sepsis and infection, cyanotic (grey/blue tinge) mucosa indicates hypoxia and pale coloured mucosa may indicate anaemia, haemorrhage and shock (Hamilton, 2003). If any abnormal results were evident after monitoring the cardiovascular system, the veterinary surgeon should be informed as soon as possible.
Blood pressure
Blood pressure is the pressure of the blood against the wall of the arteries, it occurs as a result of two forces. One force is created by the heart as it pumps blood into the arteries and through the circulating system. The second force is from the arteries themselves as they resist the flow of blood (Hamilton, 2003). Methods of monitoring blood pressure include two non-invasive techniques: doppler and oscillometric technique. Doppler technique measures systolic pressure with oscillometric monitoring systolic, diastolic and mean blood pressure.
Direct arterial blood pressure monitoring, also known as the invasive technique, is considered the gold standard in monitoring blood pressure (Welsh, 2003). A catheter is placed into a peripheral artery in dogs or the femoral artery in cats. This method is employed where accurate monitoring of blood pressure is required, for example in particularly sick or complex cases. The arterial catheter can be maintained during the recovery period and used for monitoring blood pressure in intensive care.
Hypotension, mean arterial pressure <60 mmHg, has many causes. The treatment of hypotension under anaesthesia is not considered in this article. Changes in blood pressure during the recovery period is an under researched area, however if a patient has experienced hypotension during the surgical procedure then in the recovery period it is expected that the blood pressure will normalize. Failure to do so is a complication which requires immediate treatment.
Hypertension, mean arterial pressure >150 mmHg, may occur, although it has not been documented in the recovery period.
If hypotension or hypertension is evident during recovery an increase or decrease in perfusion can occur to major organs with a possibility of damage occuring. Blood pressure is therefore best monitored in the early stages of recovery. As the anaesthetic agent wears off unresolved hypotension should resolve, assuming there are no further complications. If any hypotension or hypertesion is evident, the veterinary nurse should inform the veterinary surgeon as a soon as possible.
Respiratory
Respiratory rate should also be monitored in conjunction with auscultation of the chest. Observation of movement of the chest, respiration rate and character can be important especially in the early stages of recovery because of the possibility of respiratory impairment from certain anaesthetic drugs. Normal respiration rate in the dog is 10–30 beats per minute (bpm) and in the cat 20–30 bpm (Welsh, 2003). It is, however, to be expected that the respiratory rate will fall out of these values as numerous different factors can affect respiratory rate, such as medication administered. Ideally the veterinary nurse should be familiar with auscultation of a normal chest to enable him/her to distinguish any deterioration.
Capnography measures the CO2 concentrations in expired gas. The data can be displayed in wave form and the CO2 level at the end of expiration is displayed in numerical format. This is referred to as end tidal carbon dioxide (ETCO2). Capnography may be used to assess adequacy of ventilation until the point of extubation.
Pulse oximetry measures the percentage of arterial oxygen saturation of haemoglobin. Haemoglobin is the medium by which oxygen is transported through the body. A measurement is taken by placing a probe containing two light sources across a well perfused area of tissue, for example the tongue, pinna, prepuce or vulva. This technique is non invasive and provides continuous monitoring. Any decrease in oxygen satuation levels may indicate hypoxia or severe haemorrhage (Welsh, 2003) and oxygen supplementation must be provided and the veterinary surgeon notified as soon as possible.
Temperature
Monitoring temperature during recovery is very important. The aim is to maintain normothermia in anaesthetized patients. The chosen warming method used for the patient during anaesthesia should be continued into the recovery period unless a known more sucessful method is available such as an incubator with a warming device built in. Attention should be paid to temperature of the recovery room and any intravenous fluids being used. An efficient way to provide supplementary heat is with the use of a forced warm air blanket or heat mat. All recovering animals should always be covered with a blanket because most heat loss (40%) occurs due to radiation (Hamilton, 2003).
Analgesia
One responsibility of veterinary nurses is to ensure that patients do not suffer. Assessment of pain plays an important role in nursing care, which includes adequate pain relief before, during and after any surgical procedure. Animals should be pain scored at intervals appropriate to their analgesia plan. Pain scoring can be very useful in determining whether an animal is experiencing pain post operatively, there are many different methods for assesing pain but these generally include an interactive assessment with the patient (Crompton, 2010). If an animal has undergone a procedure where pain is anticipated and appears to be in pain then analgesia should be provided along with regular pain scoring.
General nursing considerations
Monitoring is an important part of surgical recovery, however, maintaining individual case specific nursing care is vital. A Dachshund that has had a hemilaminectomy will have completely different nursing requirements in comparison to a cat with a tibial fracture repair. Therefore during recovery, the nursing care needs to be adapted to the needs of the patient that is receiving that nursing care.
The idea of planning nursing care for a patient was first developed in the 1970s (Cox, 1995). Until this time, patients were admitted, treated, and discharged with little nursing care provided to ensure comfort during their stay (Aggleton and Chalmers, 2000). If a patient experiences a surgical procedure then the nursing care for that patient should consist of methods of nursing to aid in a quicker, safer recovery.
The author suggests that a simple form may be devised (Figure 4) for the veterinary practice to use in the surgical recovery of patients. Its use on patients would highlight potential problems that could arise and the intervention needed to resolve these problems. To apply this in veterinary practices today a recovery form would be ideal to ensure all areas of care are being covered and that the plan is individualized for that patient with the ultimate aim of reducing the risk during the post-operative recovery period. O'Connell et al (2000) have discussed that clinical protocols can contain information highly specific to a patient population and it may be necessary to consider different documentation strategies and forms for different speciality areas.
Subject areas to consider may well include continuation of intravenous fluid therapy until the patient is eating adequately, keeping the intravenous catheter patent with regular heparinized saline or insertion of a feeding tube. A feeding tube is ideal in patients that are expected to be inappetent after surgery or patients that are hypotensive during surgery. Another factor to consider is the best position for recovery; if the patient has had a prolonged surgical procedure in lateral recumbency then recovering the animal in sternal recumbency will reduce the risk of hypostatic pneumonia and reduce muscular discomfort (Scott and McLaughlin, 2007).
For patients that are expected to be non-ambulatory for a period following surgery, for example a spinal condition, thought should be given to placement of an indwelling urinary catheter or manually expression of the bladder, with the veterinary surgeon's permission. This would reduce discomfort and stress, urine scalds and keep the patient clean and comfortable on recovery.
In addition, analgesia and antibiotic therapy should be considered; if it is thought that these are needed a verbal request should be made to the veterinary surgeon. These should be documented on the patient's hospitalization sheet or recovery plan so that the numerous nurses that will be caring for the patient can easily see when more medication is required or when to assess for pain.
Grooming may also be required, especially for cats, to prevent build up of poor coat condition and matted fur, especially if an Elizabethan collar is used; this will also help reduce stress as cats may not express their normal behavior and will not be able to keep their own coat clean and tidy. Other factors to consider during the post-operative period are dependant on gender, age and the type of procedure the patient has experienced.
Conclusion
Research on mortality in animals during the recovery period has clearly shown that a lack of continuous monitoring is a major contributory factor (Brodbelt, 2006). Critical problems are not highlighted if monitoring is not performed, and this may, therefore, be an area in which improvements are required. Monitoring of the patient's cardiovascular and respiratory system, along with temperature, should ideally be continued into the recovery period until all of the patient's vital parameters have normalized. If this monitoring is performed then mortality rates may decrease as any change in a patient's vital parameters will by highlighted, so that effective action can be performed to prevent the patient's state becoming critical.
As well as improved monitoring every patient should be assessed individually and nursing care should be provided and planned, including case specific needs for each patient using primary nursing.
A combination of improvements in monitoring and individualized patient care could result in a noticeable improvement in post-operative mortalities.