Jennie April Walker, BSc (Hons), RN, DipCPC.
Staff Nurse, Spinal Trauma and Disorders Unit, Queens Medical Centre, Nottingham
Cardiovascular observation of the postoperative patient is achieved through the accurate measurement and continual monitoring of blood pressure and heart rate. Although accurate measurement of blood pressure is vital, it may be deceptive on occasions due to the body’s compensatory mechanisms. For example, in the presence of hypovolaemic shock the blood pressure may remain within normal parameters initially. However, as the severity of the shock increases the patient’s compensatory mechanisms begin to fail. Increased heart rate and respiratory rate are commonly the two earliest indicators of shock.
Shock (the circulatory failure that results in the inadequate perfusion of tissues and organs) may be characterised by a decrease in blood pressure and a rapid weak pulse (Collins, 2000), along with an ashen pallor accompanied by restlessness and anxiety. Similarly, haemorrhage may be characterised by a decrease in blood pressure and a rapid thready pulse (Alexander et al, 1994), with a developing pallor, restlessness and an altered level of consciousness. A tachycardia or hypertension may also indicate fear, pain or fluid overload (Royle and Walsh, 1992).
When assessing heart rate it is essential not only to note the presence and rate, but also to assess the regularity and quality of the pulse (see panel). A normal heart rate is typically between 60 and 100 beats per minute (Ahern and Philpot, 2002), although it is generally lower in athletes and patients with spinal cord injuries.
Cardiac arrhythmias may arise following surgery and may lead to a cardiac arrest if ventricular in nature; these will need ECG monitoring and medical advice. Acutely ill patients with hypocalcaemia or hypercalcaemia are also at risk of developing cardiac complications and should be nursed using cardiac monitoring, where available, in addition to the recording of a 12-lead ECG. If cardiovascular observations are not performed as directed by the patient’s condition then early indicators can be missed and the patient is at risk of developing complications which may go unnoticed.
Circulatory system monitoring
The measurement of central venous pressure (CVP) provides a useful insight into the circulatory system as it indirectly assesses the patient’s fluid status (Sheppard, 1997). Although a single CVP reading is frequently misleading, a trend is often useful in the clinical setting. This is helpful in identifying patients with or at risk of hypovolaemia following surgery. Unfortunately, the literature varies in what a normal CVP range is. However, it is generally accepted that this is 3-12cmH2O or as directed by the anaesthetist. CVP monitoring is often useful in identifying patients with or at risk of developing hypovolaemia, especially when acutely ill or following surgery.
Patients following surgery are vulnerable to fluid and electrolyte imbalance due to many factors, including blood loss, fasting for long periods and exposure during surgery (Iggulden, 1999). Hence an accurate measurement of the patient’s fluid balance is an essential factor in evaluating the patient’s condition. This should include strict readings of the output of drains and stomas as well as urine and vomit, and the measurement of fluid intake (oral, nasogastric and intravenous). Wound drainage sites and the surgical wound itself should be inspected at regular intervals for excessive blood loss, as this may indicate haemorrhage, and should be acted upon as directed by medical personnel. Other factors that should be taken into account include diarrhoea, burns, sweating and the use of diuretic therapy.
There are several categories of urine output as described by Smith (2000) (Box 1).
Oliguria is one of the early indications that a patient’s condition may be deteriorating. The identification of the causes of diminished urine output is essential in the treatment strategy; however, failure to act promptly or appropriately may result in the development of acute renal failure. Smith (2000) describes the oliguric patient as having a urine output of <0.5mg/kg/hour or less than 200ml in six hours. It should be noted that, although patients may produce sufficient volumes of urine, this is not indicative of renal function, which should be monitored through the examination of serum urea, creatinine and electrolytes.
Hypovolaemia is one of the most common reasons for oliguria in acutely ill and postoperative patients. However, oliguria may be a result of polyuria caused by renal failure, inappropriate use of diuretics, or increased blood glucose levels.
Disability (neurological status)
A patient’s general condition, orientation and responsiveness postoperatively help provide a more complete picture. Signs of deterioration in levels of consciousness require urgent attention and should be closely monitored using a neurological observation assessment chart such as the Glasgow Coma Scale. Any changes in the patient’s behaviours or levels of consciousness should be reported to the appropriate medical personnel.
Temperature is another measurement that is often neglected within practice despite its importance in assisting health-care professionals to monitor the patient’s condition. The surgical patient is at risk of both hypothermia and pyrexia in the immediate postoperative phase; neither of these are conducive to the patient’s well-being and appropriate management should be taken to bring the temperature within normal limits (36-378C) (Watson, 1998). Hypothermia in acutely ill patients may also be an indication of bacterial infection or sepsis. Malignant hypothermia is rare although may be induced by some anaesthetics, diuretics and antibiotics (Connell, 1997) and therefore all patients should have their temperature monitored at regular intervals. Therapeutic hypothermia is often used within surgery to slow the body’s metabolism and reduce its need for oxygen, therefore preserving ischaemic tissue during the surgical procedure.
Although postoperative care is a daily occurrence within many areas of practice, it is evident that the theory underpinning nursing actions is often forgotten in daily practice and hence actions may not be prioritised as they should be. It is hoped that this paper has enabled the reader to revisit the principles underpinning postoperative care. Such care must be viewed as a priority, and although there are local policies in place to guide nursing staff, the responsibility for understanding the reasons for actions lies with each individual practitioner.
Monitoring the cardiovascular system is essential as it may provide early indications of a variety of complications that may occur immediately postoperatively or in the care of the acutely ill patient. These include the risk of haemorrhage, shock or fluid overload. It is important to pay attention to patients’ skin colour when assessing circulatory status as signs of sweating or pale/cool limbs may indicate a reduced peripheral perfusion. Gauging the capillary refill time (CRT) may be useful in the assessment of the circulatory status:
- Press fingertip against the skin for approximately five seconds and then release
- Assess the skin site where pressure was applied - the colour should return to the skin within two seconds
- If CRT >2 seconds - this indicates poor peripheral perfusion
The heart rate can be assessed by counting the pulse rate. The arterial pulse should be assessed for rate, rhythm and amplitude (volume) at various locations on the body (Figure 1). The radial or carotid pulse can be palpated and counted for 60 seconds in order to determine the heart rate. The rhythm should be assessed and amplitude noted (Royle and Walsh, 1992).
Pain and discomfort are also important factors in the patient’s postoperative period as good pain control is required for an optimal physical and psychological recovery. If pain is well controlled the patient is able to move and exercise without excessive difficulty, thus reducing the risk of complications developing associated with prolonged bedrest.
Related problems such as nausea and vomiting can often cause the patient further distress and reduce the individual’s ability to cope with postoperative pain and discomfort, and therefore should be addressed.
FACTORS AFFECTING PAIN TOLERANCE
The perception of pain can vary greatly between patients, as can the way nurses interpret the information that they receive from the patient when applying a pain assessment tool (adapted from Seers, 1998):
Factors affecting a patient’s tolerance
Factors affecting nurses’ assessment
- Social class
- Inference of pain
- Professional training
- Duration of pain
- Type of operation
Commonly used postoperative analgesics include:
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Collins, T. (2000) Understanding shock. Nursing Standard 14: 49, 35-39.
Connell, F. (1997) The causes and treatment of fever: a literature review. Nursing Standard 12: 11, 40-43.
Iggulden, H. (1999) Dehydration and electrolyte disturbance. Nursing Standard 13: 19, 48-56.
Nursing Times. (2003) Taking the pulse. (Clinical skills). Nursing Times 99: 14, 29.
Royle, J., Walsh, M. (eds). (1992) Watson’s Medical Surgical Nursing and Related Physiology. London: Bailliere Tindall.
Seers, K. (1988) Factors affecting pain assessment. Professional Nurse 3: 6, 201-206.
Sheppard, M. (1997) Reading central venous pressure - 1 (Practical procedures for nurses 39.5). Nursing Times 96: 17, 43-44.
Smith, G. (2000) ALERT: Acute Life-threatening Events: Recognition and treatment. Portsmouth: University of Portsmouth.
Watson, R. (1998) Controlling body temperature in adults. Nursing Standard 12: 20, 49-55.