Post elective surgery

Postoperative ICU admission after elective surgery is most commonly a planned event, with the surgeon, anaesthetist, intensivist and patient all expecting a postoperative ICU stay. This may be because of the nature of the surgery (such as coronary artery bypass grafting) or because of a severe coexistent medical problem that may complicate what would otherwise be a relatively routine operation and anaesthetic. In this case, preoperative consultation with the patient’s primary medical specialist(s) is important. Optimisation of the patient’s medical problems is always desirable if time permits. In certain circumstances surgery may be best deferred or even not offered if the patient is felt to be at extremely high risk. Very occasionally, patients are admitted to the ICU preoperatively for line insertion and haemodynamic/respiratory/renal or metabolic optimisation.

Post emergency surgery

Certain presentations, such as severe trauma, often necessitate time-critical surgery. In these instances ICU care may be instigated without a full knowledge of the patient’s prior functional state, comorbidities or previously expressed wishes. Every effort should be made to access this information as soon as possible to aid in ongoing decision making.

Unplanned admission from the surgical ward

Postoperative deterioration on the surgical ward is not an uncommon problem and patients may require admission to the ICU. Many hospitals nowadays have a rapid response or medical emergency (MET) team to intervene early in the patient’s course and either avert an ICU admission or facilitate rapid transfer to the ICU or operating theatre. This response service may be activated by any member of the medical or nursing staff and calling criteria are based on a set of physiological variables including pulse rate, respiratory rate, blood pressure and conscious state.

Scoring systems

There have been a number of scoring systems developed to quantify how ‘sick’ a patient is on admission to the ICU and to predict patient outcomes. Examples of such scoring systems are the acute physiology and chronic health evaluation score (APACHE) and the simplified acute physiology score (SOFA). Although very useful, none of these systems are yet accurate enough to predict outcome for individual patients.

Monitoring — an overview

Monitoring is one of the mainstays of intensive care. It allows for early detection and treatment of problems and to observe and titrate any interventions made. Monitoring may be invasive or noninvasive and includes point of care tests such as arterial blood gases (Table 12.1).

Table 12.1 Examples of monitoring by systems

Intra-arterial and central venous pressure access

Intra-arterial blood pressure monitoring allows continuous ‘beat to beat’ monitoring of the blood pressure. This is achieved by inserting a catheter into an artery, most commonly using the Seldinger technique of entering a vessel with a needle, inserting a guidewire and then threading the catheter over the guidewire. The catheter is then attached to a pressure transducer and levelled at the phlebostatic axis (the level of the tricuspid valve). Common arterial sites selected are radial (Fig 12.2), femoral and dorsalis pedis. Complications include arterial occlusion, arterial dissection, distal ischaemia and embolisation, infection and bleeding. There are many case reports of limb or digit loss secondary to one of these complications. For this reason, end arteries such as the brachial artery or the femoral artery in young children are less commonly preferred.

Figure 12.1 Swan-Ganz catheter

A: line to inflate the balloon in pulmonary microvasculature; B: line for measuring pulmonary capillary (left atrial) wedge pressure; C: line for measuring right artial pressure; D: thermistor catheter for measuring cardiac output by thermodilution

Figure 12.2 Radial artery cannulation

Central venous cannulation allows for measurement of the central venous pressure and for administration of drugs into the central circulation. Central venous catheters may be single or multilumen and are usually inserted via the Seldinger technique. Common sites (Fig 12.3) include the internal jugular, subclavian and femoral veins. These veins are often localised by ultrasound prior to insertion. The catheters are placed so the distal tip lies in the superior vena cava (SVC) for internal jugular and subclavian catheters. Complications relate to either their insertion (pneumothorax, arterial puncture, haemothorax, haematoma) or presence in a central vein (blood stream infection, venous thrombosis/embolisation, venous perforation etc).

Figure 12.3 Central venous catherisation

A: infraclavicular approach. A short 15-gauge needle is passed below the clavicle near the junction of the middle and lateral thirds and directed towards the suprasternal notch. B: internal jugular approach. The needle is inserted lateral to the sternomastoid muscle about two fingers above the clavicle and directed towards the suprasternal notch.

Nursing care

The bedside nurse plays a vital role in the overall care of the intensive care patient, being responsible for monitoring the patient’s overall status and vital signs, implementing the physician’s therapeutic plan and attaining physiological targets, administering medications and infusions and, often, adjusting and running the various machines attached to the patient, such as the ventilator or haemodialysis machine. Nursing staff are often in the best position to first notice a change in the patient’s condition and then notify the medical staff. Communication between the two groups is absolutely of paramount importance.

In addition to the above, other tasks such as providing patients’ personal care and giving information and reassurance to family members and patients are equally important.

Meticulous nursing care and attention to detail is one of the factors most responsible for a patient’s recovery and smooth transition through the ICU to the ward.

Organ preservation

Preservation of organ systems and support of their functions is one of the cornerstones of ICU management. In any patient, but particularly the critically ill, avoidance of hypoxaemia and hypotension is vital to prevent further, secondary injury to organ systems already damaged by the primary insult. This is achieved by maintenance of oxygen delivery to the tissues (i.e. reversal of shock), optimisation of the patient’s volume state, correction of severe metabolic abnormalities, neuroprotective strategies in central nervous system injury and other directed therapies to assist recovery, such as early antibiotic treatment of infection and surgical drainage of abscesses.

Individual organ system dysfunction and supports will be discussed further later in this chapter, as will sepsis.

Wound healing in the ICU

Intensive care patients often have significantly impaired wound healing, which is due to a multitude of factors. As can be imagined, poor wound healing, wound breakdown and susceptibility to infection can have a major adverse effect on a patient’s recovery from surgery.

Poor wound healing may be due to a number of causes such as:

Intensive care management of these problems includes meticulous nursing care of wounds, optimisation of nutritional and metabolic parameters and aggressive, early (medical and surgical) treatment of infection.

Pain management

Pain is often a significant management issue in the postoperative ICU patient. Uncontrolled or poorly controlled pain, as well as distressing the patient, may manifest as haemodynamic instability, difficulty with breathing and ventilation (mechanical or spontaneous), increased bleeding due to hypertension or extreme agitation. This is turn can lead to a greater length of mechanical ventilation, longer ICU stay and more complications. On the other hand, good analgesia assists with recovery, physiotherapy and mobilisation, as well as improved patient wellbeing.

Provision of pain management in the ICU may be undertaken solely by the intensive care staff but is often run in conjunction with a pain service. This team, often led by anaesthetists, assists and guides with pain management and is able to follow patients through ICU and continue to manage their pain on the surgical ward.

A full rundown of all the modalities of pain management available in the ICU is beyond the scope of this book. However, in broad terms analgesia may be systemic — that is, intravenous or oral medications — or regional (epidural or intrathecal catheters, nerve blocks etc). It is also worth remembering that in the ICU the sedative effects of some agents, such as morphine, may well convey an additional advantage over their purely analgesic effects. This can, however, be a double- edged sword in terms of gaining adequate analgesia while also attempting to wean from mechanical ventilation.

Nutrition

Intensive care patients pose special challenges in terms of the provision of adequate nutrient intake. Critical illness imposes great stresses on the body and critically ill patients are often profoundly catabolic, even with the provision of seemingly adequate feeding. Added to this is the fact that a significant proportion of ICU patients enter the unit with pre-existing nutritional deficiencies as a result of either their acute illness or a more chronic condition. This has a significant impact on their ability to combat critical illness and increases the challenge of providing adequate nutrition.

A number of methods are used to determine the ideal amount of nutrition a patient should receive. One common formula used is the Schofield equation.

Once the amount of energy required is decided upon, nutrition is provided in the ICU by one of two routes: enteral or parenteral. Occasionally, combination therapy is used.

Enteral feeding

Enteral feeding uses the patient’s gastrointestinal tract to provide nutrition and is generally the preferred route in the ICU. This may occur by having the patient eat in the usual manner, but in ICU it usually occurs by administering a prepared feeding formula into the patient via a nasogastric or nasojejunal tube. It may also be administered via a PEG or PEJ (a percutaneous feeding tube into the stomach or small bowel respectively; Fig 12.4). Initially small volumes of food are used, with a gradual escalation to a target volume. Enteral feeding has the advantage of using the patient’s own gastrointestinal tract, is usually relatively noninvasive and confers protective effects on the stomach and intestines. The major drawback is that critically ill patients often have gastrointestinal dysfunction such as gastroparesis or ileus that limits absorption or have had surgery or bowel injury that prohibits the use of the native gut.

Figure 12.4 Percutaneous jejunostomy

Parenteral feeding or total parenteral nutrition (TPN)

Parenteral feeding involves the infusion of a specially formulated solution into a central vein via a dedicated catheter (CVC or Hickman) (Fig 12.5). It is usually only used in situations where enteral feeding is contraindicated. It has the advantage of having guaranteed delivery of nutrients into the body (Fig 12.6) but has a number of drawbacks. First, it is quite invasive because it requires the placement of a dedicated catheter into a central vein, with all the potential complications that this entails (see above). It has also been associated with an increased risk of blood stream infection via this catheter. Other problems include electrolyte and water balance, hyperglycaemia and hyperlipidaemia.

Figure 12.5 Hickman catheter

A: a silicone catheter is inserted into the right atrium via the cephalic vein: B; subcutaneous tunnel; C: a teflon cuff reduces ascending infection and prevents inadvertent removal

Figure 12.6 Parenteral nutrition

A: container for replacement of abnormal losses and drug infusion; B: balance nutrient solution; C: monitoring pump; D: Hickman catheter; E: bag for collection of fistula loss; F: urinary catheter; G: blood collection for routine measurement of Na, K, Cl, PO₄, HCO₃, glucose, urea, creatinine, albumin and osmolality