Critical Care of the Post-Surgical Patient, Dr med vet, DEA, DECVIM-CA Many critically ill patients require surgical treatments. These patients often have multisystem abnormalities during the immediate post-surgical phase as a result of their primary disease process, the surgery itself and the effect of anaesthesia. Careful monitoring and nursing care can make all the difference between life and death in these patients. Specific monitoring and treatments are dictated by the primary disease process, however, in the post-surgical patient, particular attention should be paid to the respiratory and cardiovascular systems, thermoregulation, analgesia, fluid balance and general nursing care. While techniques such as pulseoximetry or electrocardiography (ECG) are useful in the post-operative patient monitoring, the importance of close observation and physical examination of the patient cannot be overemphasised. Airway and Breathing Anaesthesia can affect the respiratory system in many ways. Most anaesthetic drugs depress respiratory function and the ability of the patient to guard its airway (swallowing reflex). Regurgitation and vomiting are common during the post-surgical phase and can lead to aspiration pneumonia. Prolonged recumbency during surgery can lead to decreased gas exchange in the dependant lung lobes. During recovery from anaesthesia it is therefore crucial to closely monitor the respiratory function of the patient. The animal should remain intubated, and in dogs, the endotracheal tube should remain inflated, until it can actively swallow and is fighting the endotracheal tube. Administration of nasal oxygen during the anaesthetic recovery phase is advised for all critically ill patients. The patient s respiratory rate, respiratory character and mucous membrane colour should be closely monitored in order to detect potential respiratory depression (decreased rate or depth of the respiratory movements) and decreased oxygenation (hypoxaemia). Unfortunately, physical examination only
detects abnormalities once they are severe. Therefore it is helpful to use additional monitoring techniques, if available. Arterial blood gas analysis can be used to assess both ventilation (PaCO 2 ) and oxygenation (PaO 2 ). End-tidal carbon-dioxide can be measured continuously via a capnograph in the expired air either by connecting the probe to the endotracheal tube or holding it up against the nostrils of the animal. The oxygen saturation of haemoglobin can be easily assessed via pulse-oximetry. As long as the animal is asleep the probe of the pulse-oximeter can be placed on a nonpigmented area on the tongue or the lip. As the patient awakes the probe can be put on the pinna or the ear or the interdigital space. If the patient s respiratory function is compromised, re-intubation and positive pressure ventilation using an Ambu bag or an anaesthetic circuit may be required in order to maintain adequate ventilation and oxygenation. Cardiovascular function Hypotension can be a problem in the critically ill post-surgical patient and can be due to hypovolaemia, vasodilation or decreased myocardial contractility. Blood pressure should be monitored either directly via an arterial catheter or indirectly via Doppler or oscillometric technique. Hypotension can lead to hypoperfusion of vital organs and therefore needs to be aggressively treated. Treatment depends on the underlying cause and consists of fluid administration in case of hypovolaemia, vasopressors in case of vasodilatation and positive inotrope agents (promoting the force of cardiac contractions) in case of poor cardiac contractility. Continuous ECG monitoring is useful in order to detect disturbances of the cardiac rhythm or changes in heart rate, which may flag cardiovascular compromise, pain or anxiety. Cardiovascular abnormalities should be aggressively treated because they can be immediately life-threatening. Hypothermia Hypothermia is a common complication of general anaesthesia. Efforts should be made to prevent severe hypothermia from developing intra-operatively by using
circulating warm water- or warm air blankets, warming of IV fluids and lavage of body cavities with warmed sterile fluids. Postoperative hypothermia can decrease the metabolism of anaesthetic drugs and therefore can slow anaesthetic recovery. Hypothermic patients should be actively warmed up. Once the patient has reached a temperature of 38 C active warming efforts should be stopped in order to prevent accidental overheating. Pain management Post-operative analgesia should be administered with the intent that the animal should never be allowed to be in pain. However, during the immediate postoperative phase it can be difficult to differentiate between pain and dysphoria. If a patient is unsettled or vocalising, the surgical site should be assessed for pain and the current analgesic treatment reassessed. Additional analgesia should be administered if necessary. If the patient is still uncomfortable, other causes should be considered such as a full bladder, attention seeking or dysphoria due to opioid drugs. If dysphoria is likely, a change in the analgesic protocol may be necessary. Fluid balance, electrolyte and acid-base status, coagulation Ideally, abnormalities of the fluid balance, electrolyte and acid-base status should be corrected before the animal undergoes surgery. Post-surgery fluid therapy should aim to maintain proper hydration and perfusion of the patient and correct electrolyte disturbances (e.g. hypokalaemia) and acid-base disturbances (e.g. metabolic acidosis) if present. Coagulation disturbances can occur in the critically ill patient because of use of colloid solutions, blood products or disseminated intravascular coagulation (DIC). Routine monitoring should include careful assessment of physical perfusion and hydration parameters (i.e. mucous membrane colour and refill time, peripheral pulse quality, urine output) and, if available, packed cell volume (PCV), total solids (TS), electrolytes (Na +, K +, Cl -, HCO - 3 ) and for some cases coagulation profiles (PT, aptt, D-Dimers).
Nutrition Nutritional support is one of the most important aspects of promoting healing. Patients should be encouraged to eat once fully recovered from anaesthesia with very few exceptions (e.g. severe dysphagia or intractable vomiting). An appropriate feeding tube should be placed during surgery if post-operative inappetence is anticipated. Patient cleanliness Patient cleanliness is of paramount importance during the post-operative phase. Wound secretions, faeces, urine, vomitus and contaminates for the external environment can lead to infection of the surgical wound or catheter sites and scalding. The surgical wound and all catheter sites should be covered to prevent contamination. In many cases contamination of the wound origins from the hands of the carers! Therefore whenever bandages are changed, personnel should wash their hands carefully and wear gloves for the protection of the patient. Wounds and catheter sites should be checked at least once or twice daily for redness, tenderness, pain or secretion. Any bandage showing evidence of soiling or strikethrough should be changed immediately and discarded. Bedding should be checked and changed regularly. In recumbent patients the placement of a urinary catheter should be considered in order to prevent urine scalding. Patient mobilisation and physiotherapy Recumbent patients are at risk for poor aeration of the dependant lung lubes, pneumonia and decubital ulcers. These patients should therefore be turned from side to side and into sternal recumbency at least every 4-6 hours in order to promote adequate ventilation and prevent development of decubital ulcers over pressure points. Particular attention should be paid to ensure adequate padding for these patients. Physiotherapy, including massage and passive range-of-motion exercises, should be performed 3-4 times daily to prevent stiffness and promote lymph
drainage. If possible patients should be encouraged to stand or towel walk in order to prevent loss of muscular strength. Psychological needs Critically ill animals are stressed animals. Taking care of these patients should also address their mental needs. Visits from caretakers and the animal s family without providing any therapy other then tender loving care can make a huge difference for the animal s recovery.