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Core Topics in Critical Care Medicine

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  • 91 b/w illus. 105 colour illus.
  • Page extent: 408 pages
  • Size: 246 x 189 mm
  • Weight: 1.2 kg

Library of Congress

  • Dewey number: 616.028
  • Dewey version: 22
  • LC Classification: RC86.7 .C667 2010
  • LC Subject headings:
    • Critical care medicine
    • Critical Care--methods

Library of Congress Record

Hardback

 (ISBN-13: 9780521897747)

Core Topics in Critical Care Medicine
Cambridge University Press
9780521897747 - Core Topics in Critical Care Medicine - Edited by Fang Gao Smith and Joyce Yeung
Excerpt

Chapter 1    Recognition of critical illness

Edwin Mitchell

Initial assessment and resuscitation

General considerations

  • Critical illness, simply defined, is a state where death is likely or imminent. All of us will experience a critical illness by definition, but the aim of intensive care is to identify patients whose critical illness pathway can be altered and steered away from a fatal outcome.

  • Over the past decade, it has become clearer that intervening earlier in a patient’s critical illness may lead to improved survival. Even when life-prolonging treatment is no longer in the patient’s best interests, acknowledging a patient is critically ill and in the terminal phase of their illness allows appropriate palliative care to be given.

  • Critical illnesses are characterized by the failure of organ systems, and it is the signs of these organ failures that the initial assessment hopes to identify. Commonly, organ systems fail in sequence over time leading to multi-organ failure, and resuscitation aims to limit this. Mortality is proportional to the number of failed organs, duration of dysfunction and severity of organ failure.

  • In contrast to the treatment of many routine medical conditions, where definitive treatment is based on a thorough assessment of the patient, the assessment of the critically ill patient typically occurs simultaneously with treatment due to clinical urgency.

Assessment

  • The initial assessment of the critically ill patient should begin with a brief, targeted history and an appraisal of the patient’s vital signs to identify life-threatening abnormalities that merit immediate attention. Signs suggesting severe illness are listed in Table 1.1.

  • Most physicians are familiar with the ‘ABCDE’ (Airway, Breathing, Circulation, Disability, Exposure) approach to patient assessment taught on Advanced Life Support™, Advanced Trauma Life Support™ and other nationally recognized courses. This approach is speedy, thorough and adaptable, compared to the traditional medical ‘clerking’.

  • The principle behind the ABCDE approach is that problems are prioritized according to the severity of threat posed. Serious physiological derangements should be dealt with at each stage before moving on to assess the next step. For example, an obstructed airway should be identified and cleared before assessing breathing and measuring blood pressure.

  • In reality, information is gathered in a non-linear fashion, but it is helpful to have a clear guideline within which to work. With adequate staff training and numbers, it should be possible to deal simultaneously with multiple problems.

  • Common signs of organ failure should be sought, and bedside monitoring equipment (such as pulse oximetry, automated blood pressure measurement devices and thermometers) may augment the clinical examination. Near-patient testing, using equipment such as the Haemacue™, and arterial blood gas sampling can provide useful and rapid information regarding the oxygenation of the patient and common derangements in acid–base status and haemoglobin.

Resuscitation

  • The purpose of resuscitation is to restore or establish effective oxygen delivery to the tissues, in particular those of the vital organs – brain, heart,


    Table 1.1 Signs suggestive of critical illness
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    kidneys, liver and gut. Oxygen delivery depends on adequate oxygen uptake from the lungs, an adequate cardiac output to deliver the oxygen to the tissues and an adequate haemoglobin concentration to carry the oxygen.

  • These goals of resuscitation are usually achieved by the use of supplemental oxygen, fluid or red blood cell transfusion, inotropic support or antibiotics as needed. In certain circumstances, such as penetrating trauma, a surgical approach to limiting life-threatening bleeding is considered to be a part of the resuscitation process.

  • Resuscitation should begin as soon as the need for it has been identified. There is now evidence showing that early intervention (within a few hours of admission) limits the degree of organ dysfunction and improves survival. Waiting until the patient reaches the intensive care unit may be too long a delay if further deterioration in the patient’s condition is to be prevented.

  • In some situations, such as head injury, even single episodes of hypotension or hypoxia are associated with worsened outcomes.

  • Early and complete resuscitation is associated with improved outcomes.

Monitoring the progress of resuscitation

At present, there are only limited ways in which the function of individual tissue beds can be assessed. Assessing the adequacy of resuscitation is usually based on either global markers of oxygen supply and utilization (such as the normalizaton of mixed venous oxygen saturations and lactate concentration), or the clinical responses of the affected organs – urine output from the kidneys for example. Whilst resuscitation is ongoing, invasive monitors such as an arterial cannula, a central venous cannula and a urinary catheter may be placed, but these additional monitors should not detract from the clinical monitoring of the patient.

Table 1.2 Suggested goals to be achieved within 6 hours of presentation for the resuscitation of septic shock refractory to fluid therapy (after Rivers et al.)
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  • Resuscitation must be tailored to the individual patient. There are now data to suggest appropriate goals or parameters for resuscitation in certain clinical states, notably sepsis (Table 1.2), acute head injury and penetrating trauma.

  • Over-enthusiastic attempts at resuscitation can lead to problems with fluid overload, worsening haemorrhage through dilution of clotting factors, or rapid electrolyte shifts leading to cerebral oedema.

  • The importance of early assessment by adequately trained staff, with regular review of clinical progress, cannot be over-emphasized.

Once resuscitation is under way and the patient is stabilized, it is appropriate to begin an in-depth assessment of the patient. This means taking a more complete history, making a thorough examination and ordering clinical investigations as indicated. This phase of the process aims to establish an underlying diagnosis and guide definitive treatment. If deterioration occurs over this time, the cycle of assessment and resuscitation should begin again.

Physiology monitoring systems

Physiology monitoring systems are systems that allow the integration of easily obtained and measured physiological variables into a single score or code that triggers a particular action or care pathway (see also Chapter 5: Scoring systems and outcome).

  • The commonly measured physiological variables are heart rate, blood pressure, respiratory rate, temperature, urine output and consciousness level, and these can be assessed at the bedside.

  • Action may be triggered by a single abnormality or by an aggregate score. Aggregate scoring systems are generally preferred as they may also allow a graded response depending on the score.

  • Physiological Scoring Systems (PSS) developed from the recognition that critically ill patients, and


    Table 1.3 Advantages and disadvantages of Physiological Scoring Systems
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    in particular patients who suffered cardiac arrests, often had long periods (hours) of deterioration before the ‘crisis’ or medical emergency occurred.

  • PSS scores are often termed ‘track and trigger’ scores; they aim to identify and monitor patients whose clinical state is worsening over time, and then trigger an appropriate clinical response.

  • The Department of Health has recognized the need for the early identification of critically ill patients and recommends the use of track and trigger systems in all acute hospitals in the UK. The current recommendation is to use PSS to assess every patient at least every 12 hours or more frequently if they are at risk of deterioration.

  • PSS may have variable sensitivity and specificity for predicting hospital mortality, cardiac arrest and admission to critical care. Triggering scores may need to be set locally to maximize the benefits from these scoring systems. Typically, these scoring systems are not very sensitive but have high negative predictive power for the outcomes mentioned above. Advantages and disadvantages of PSS are summarized in Table 1.3.

Medical emergency team and outreach

It has been recognized that intensive care units will never have the capacity for all the patients that may benefit from some degree of critical care provision. The concept of ‘critical care without walls’ is that patients’ critical care needs may be met irrespective of their geographical location within the hospital.

Medical emergency teams (METs) and critical care outreach (CCO) aim to redress the mismatch between the patient’s needs when they are critically ill and the resources available on a normal ward, in terms of manpower, skills, and equipment.

  • At present there is no clear consensus in the literature about the exact composition and role of these teams, nor their nomenclature.

  • Currently there is emphasis in teaching critical care skills to all hospital doctors via courses such as ALERT™ (Acute Life threatening Events – Recognition and Treatment) and CCRISP™ (Care of the Critically Ill Surgical Patient).

  • METs are usually understood to be physician-led. The team might typically consist of the duty medical registrar and intensive care registrar, a senior nurse and a variable number of other junior doctors.

  • METs are often formed from people who do not usually work together, coming together as a team only when the clinical need dictates. The MET has an obligation to arrive quickly, to contain the necessary skill mix in its members, to document the extent of its involvement accurately, and to liaise with the team responsible for the patient’s usual treatment.

  • METs are summoned to critically ill patients who have been identified either by a scoring system as outlined above, because they have attracted a particular diagnosis (e.g. status epilepticus), or because of general concerns that the nursing staff have about a patient.

  • METs have been shown to reduce the numbers of unexpected cardiac arrests in hospital in some observational studies, but the exact level of benefit is controversial. In some hospitals METs have replaced the traditional cardiac arrest team.

Critical care outreach (CCO) teams are typically nurse-led, and have a variety of roles compared to the MET, depending on local policy (Fig. 1.1). The nurses in CCO are typically senior nurses who have been recruited from an intensive care, coronary care or acute medical background. CCO nurses are often employed full-time in this role and may perform additional duties, such as following up patients on discharge from the intensive care unit, acute pain services, tracheostomy care and providing non-invasive ventilation advice.
  • When summoned to a critically ill patient, CCO will typically make an assessment and refer directly to intensive care services, or make suggestions to the parent medical team according to the requirements of the patients.

  • At present, not all CCO are staffed to provide a round-the-clock service and thus patients still often rely on junior medical staff to provide their care out of hours.

In the UK, CCO is the most frequently used model, following on from Department of Health recommendations made in the late 1990s. Their explicit purpose is to avert ITU admissions, support discharge from ITU and to share critical care skills with the rest of the hospital. Other countries, most notably Australia, have pioneered the MET model since 1990. In some hospitals both systems run side by side. Currently the systems are in a state of flux. The rapid introduction of MET/CCO systems in most hospitals has made the assessment of its impact on patient survival difficult. It is also difficult to assess how many patients at any one time need the input of a MET/CCO, and the implications that this may have for resource allocation. At the time of writing, most of the available data suggest that the MET is under-utilized.

Referral to critical care team

Critical care can offer:

  • organ support technologies

  • high nurse : patient ratio

  • intensive/invasive monitoring

  • specialist expertise in managing the critically ill

Patients who need these services should be referred to the critical care team.

Intensive care units exist to support patients whose clinical needs outstrip the resources/manpower which can be safely provided on the general wards. The patient must also generally be in a position to benefit from the treatment, rather than simply to prolong the process of dying from an underlying condition. Chronological age alone is a poor indicator of survival from a critical illness; chronic health problems and functional limitations due to these are better predictors. There should be a discussion with the patient (if possible), or their family, to explain the proposed treatment and to seek their consent for escalating management.

Most critical care facilities operate a ‘closed’ policy, in which the referring team temporarily devolves care to the intensive care team. The latter is led by a clinician trained in intensive care. There is evidence that this approach leads to reduced lengths of stay and increased survival rates in patients. As part of this strategy, all referrals to intensive care should be passed through the duty intensive care consultant. The referring team still has an important role to play as definitive management of a condition (e.g. surgery) is still often provided by them.

Referral to the critical care team may occur via a variety of routes. The admission may be planned well in advance in the case of elective surgery, or anticipated and discussed with the ITU consultant in the case of emergency surgery. Acute medical admissions should be referred to the ITU consultant directly from the medical consultant, but in emergencies referral may be made via the MET/CCO. The patient is usually reviewed on the ward prior to admission in order to facilitate resuscitation and safe, timely transfer to critical care.

Key points

  • Early recognition and treatment of the critically ill patient may improve outcome.

  • Recognition of a critically ill patient by junior or inexperienced staff may be facilitated by a scoring system.

  • Physiological scoring systems are widely used, but not always well validated.

  • METs and CCOs aim to provide critical care skills rapidly to critically ill patients.

  • Referrals to the critical care services may happen from any level, but the final decision to admit a


    patient to a critical care bed should be made by an experienced critical care physician.

Further reading

Bickell W, Wall M, Pepe P et al. (1994) Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries. N. Engl. J. Med. 331: 1105–9.

Intensive Care Society (2003) Evolution of Intensive Care. www.ics.ac.uk/icmprof/downloads/icshistory.pdf

Intensive Care Society (2008) Levels of Critical Care for Adult Patients: Standards and Guidelines. www.ics.ac.uk/downloads/Levels_of_Care_13012009.pdf

National Institute for Clinical Excellence (2007) Clinical Guideline CG59: Acutely Ill Patients in Hospital. www nice.org.uk/guidance/index.jsp?action=byID&o=11810#summary

Rivers E, Nguyen B, Havstad S et al. (2001) Early goal-directed therapy in the treatment of severe sepsis and septic shock. N. Engl. J. Med. 345: 1368–77.




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