Assessment, diagnosis and treatment

The signs and symptoms of anaphylaxis are related to its pathophysiological causes, but may vary according to the allergen and route of exposure.

Basis of diagnosis

Diagnosis is based on (Sampson 2003, Younker and Soar 2010, Arnold and Williams 2011):

History of exposure.
Presence of risk factors.
Progression of typical signs and symptoms.

However, sampling of blood tryptase levels at the time of anaphylactic response and one to two hours later, when it is thought that levels peak, is recommended to assist in gauging improvement or deterioration in the patient’s condition (Brown et al 2004, Schwartz 2006, Younker and Soar 2010, NICE 2011). Tryptase, along with histamine and heparin, is released during mast cell activation to the allergen associated with anaphylaxis (Lab Tests Online 2010), although elevated levels are a more reliable estimate of reaction acuity in the adult than the child (NICE 2011).

Despite the fact that diagnosis should be based predominantly on clinical signs and symptoms and, where possible, confirmed by the biochemical tests outlined above, there remains a lack of consensus on the significance of certain clinical signs and symptoms in terms of their relevance to diagnosis of anaphylaxis. Therefore, some patients received doses of adrenaline as treatment where it was not necessary (Jevon 2010, Spickett and Stroud 2011). Evidence also suggests that patients who required adrenaline as first-line treatment either did not receive it or its administration was delayed (Brown 2006, RCUK 2008, Caton and Flynn 2013). General manifestations of anaphylactic reactions are divided into their effect on different body systems, as highlighted in Table 1.

Table 1

Complete time out activity 4

Consider the multiplicity and variety of signs and symptoms outlined in the module. What mistaken diagnoses do you think some patients experiencing anaphylaxis may have been given?

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Misdiagnosis made in anaphylaxis

The most common misdiagnosis made in anaphylaxis has been that of a vaso-vagal or syncope attack (Arnold and Williams 2011, Ben-Shoshan and Clarke 2011).
Other cases of anaphylaxis have been mistakenly diagnosed as ischaemic heart disease, choking episodes, hypoglycaemia, panic attacks or anxiety states, carcinoid syndrome, post-viral syndromes, drug-induced angioedema usually caused by angiotensin-converting enzyme (ACE) inhibitors, and breath-holding episodes in children.

Conversely, although less common, some of these patients have been treated as being anaphylactic (Brown 2006, Jevon 2010, Younker and Soar 2010, Arnold and Williams 2011, Spickett and Stroud 2011).

Points to remember during diagnosis and assessment

It is an important part of the assessment process to take a thorough patient history, including past medical history, drug history and recent illnesses.
Attempts have been made to provide a common definition of diagnostic criteria for anaphylaxis in an attempt to provide clarity and timely intervention for patients needing treatment (Brown 2004, Erlewyn-Lajeunesse et al 2010, Younker and Soar 2010, Arnold and Williams 2011).
The importance of systemic respiratory and/or cardiovascular symptoms in distinguishing anaphylaxis from other illnesses is emphasised.
They also highlight that erythema or angioedema in isolation do not constitute anaphylaxis; it has been noted that up to 50% of anaphylactic reactions do not feature urticarial rash as a component of the presentation (Brown et al 2001, Spickett and Stroud 2011).
Angioedema as an isolated finding is more likely to result from causes other than an anaphylactic response; the most common cause of this type of oedema in the absence of urticaria is drug induced (Spickett and Stroud 2011).

Guidelines for diagnosis

Guidelines for the assessment and management of anaphylaxis in children and adults have been developed in an attempt to standardise care and reduce the number of false positive and false negative diagnoses. Guidelines have been developed in the US (Gifford Medical Center 2011a, 2011b) and Australia (Brown 2006), and the World Allergy Organization made an attempt to standardise practice globally (Simons et al 2011). UK guidelines (NICE 2011) focused on simplification of recognition and treatment, and the use of a systematic approach to the treatment of patients considering the ABCDE approach: airway, breathing, circulation, disability (conscious level), exposure (identification of potential other ailments or injuries).

UK guidelines (NICE 2011) simplified the criteria for the recognition of anaphylaxis, stating that anaphylaxis is more likely to occur when in the presence of the following three features:

Sudden onset and rapid symptom progression.
Life-threatening airway, breathing or circulatory problems.
Dermatological changes, for example flushing, mucosal swelling, urticaria or angioedema.

Diagnosis may be supported by a history of exposure to a known allergen and there may or may not be gastrointestinal symptoms. The guidelines also simplified the dose of intramuscular adrenaline to be administered during an episode of anaphylaxis as follows (NICE 2011):

Adults and children over 12 years – 0.5mL of 1:1,000 adrenaline.
Children 6-12 years – 0.3mL of 1:1,000 adrenaline.
Children under 6 years – 0.15mL of 1:1,000 adrenaline.

Each dose may be repeated within five minutes if there is no improvement in the patient’s condition.

Complete time out activity 5

In addition to using the ABCDE approach to the assessment and management of patients, from which treatment might the person with established anaphylaxis benefit?

Once completed your time out activity is saved and stored in "My Modules”.

Access to other resources to support the person will depend on the clinical setting or environment that the episode takes place in; there may be little for a responder to do apart from administer adrenaline if available and call the emergency services (Figure 3).
Conversely, if the episode occurs where more resources are available, then using the ABCDE approach will provide focus on the priorities of resuscitation. Airway support and oxygenation may be needed and the patient may require fluid replacement if exhibiting signs of shock.
Conscious level should be monitored using a universally accepted tool such as the Glasgow Coma Scale (Teasdale and Jennett 1974) or a simplified, easy to recall system such as AVPU (A = patient is alert, V = patient responds to verbal commands, P = patient responds to pain, U = patient is unresponsive) (Jevon 2008).
Patients may need to be exposed to reveal the full extent of dermatological changes, any obvious bites or stings, and to identify angioedema.

Figure 3

It has been noted that some patients receive less than optimal care in urgent and emergency care settings, with some individuals receiving a less than therapeutic dose of adrenaline (Gaeta et al 2007), while others receive second-line drugs such as corticosteroids and antihistamines, with or without subsequent administration of adrenaline, despite the fact that their use in anaphylaxis is limited (Choo et al 2010).

In up to 20% of patients, a biphasic or ‘rebound’ episode of symptoms is observed without further exposure to the allergen (Caton and Flynn 2013). Although most of these episodes occur within six hours of treatment (NICE 2011), they may be observed up to 72 hours afterwards (Mustafa 2012).

Complete time out activity 6

Given the dangers of sub-standard care and biphasic episodes of anaphylaxis, what type of treatment and patient education should children and adults with these reactions receive from staff?

Once completed your time out activity is saved and stored in "My Modules”.

Learning points

The signs and symptoms of anaphylaxis are related to its pathophysiological causes, but may vary according to the allergen and route of exposure. Diagnosis is based on history of exposure, presence of risk factors, and progression of typical signs and symptoms.
Sampling of blood tryptase levels at the time of anaphylactic response and one to two hours later, when it is thought that levels peak, is recommended to assist in gauging improvement or deterioration in the patient’s condition. Tryptase, along with histamine and heparin, is released during mast cell activation to the allergen associated with anaphylaxis.
UK guidelines simplified the criteria for the recognition of anaphylaxis, stating that anaphylaxis is more likely to occur when in the presence of three features: sudden onset and rapid symptom progression; life-threatening airway, breathing or circulatory problems; and dermatological changes, for example flushing, mucosal swelling, urticaria or angioedema.
Conscious level should be monitored using a universally accepted tool such as the Glasgow Coma Scale or a simplified, easy to recall system such as AVPU (A = patient is alert, V = patient responds to verbal commands, P = patient responds to pain, U = patient is unresponsive).
Some patients get less than optimal care in urgent and emergency care settings, with some individuals receiving a less than therapeutic dose of adrenaline while others receive second-line drugs such as corticosteroids and antihistamines, with or without subsequent administration of adrenaline, despite the fact that their use in anaphylaxis is limited.

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