Preoperative Consideration in Common Pathological and Nonpathological Conditions


Level

Step

Steroids

Add therapy

1

Mild intermittent asthma

No

Inhaled short-acting β2-agonist as required

2

Regular preventer therapy

Up to 400 mcg/die BDP

LABA

3

Initial add-on therapy

Up to 400 mcg/die BDP

LTRA

4

Persistent poor control

Up to 800 mcg/die BDP

LABA/LTRA/aminofillina

5

Continuous or frequent

use of oral steroids

Other doses of BPD (≥800 mcg/die) and per os steroids

Use daily steroid tablet in lowest dose providing adequate control


Patients should start treatment at the step most appropriate to the initial severity of their asthma. Check concordance and reconsider diagnosis if response to treatment is unexpectedly poor. BPD beclomethasone dipropionate, LABA long-acting β2-agonist, LTRA leukotriene-receptor antagonist



A difficult asthma is a poorly controlled asthma despite high doses of inhaled steroids (≥800 μg/day of beclomethasone dipropionate (BDP) or belonging to levels 4 and 5). Although some asthmatic children may be unresponsive to steroids, the most common reasons for a “difficult asthma” are the low compliance to treatment, inadequate technical capacity with the inhaler, or an incorrect diagnosis of asthma [28].

A small group of children with severe asthma may be at risk of life. Those children may have a poorly controlled asthma or a “fragile” asthma with asthma attacks of sudden onsets, which simulate an asphyxiating or anaphylactic reaction. A history of serious recent exacerbations especially if they required admission to the ICU is indicative that a child is particularly vulnerable to a sudden attack, which may be precipitated by nonsteroidal analgesics or anesthetic vapors [29].

Children who take medication only during exacerbation should start taking the same drugs (inhaled β2-agonists or oral medications) and doses used during exacerbation, on a regular basis 3–5 days before surgery [30]. The benefits on airway reactivity are evident after 6–8 h with a maximum effect between 12 and 36 hours.

Children receiving asthma medication on regular basis should continue with usual administered treatment. The administration of β2-agonists (e.g., salbutamol) before the induction of anesthesia may prevent the increase of airway resistance associated with halogenated anesthesia [13] and URIs [12].

Children under steroid medication and those who have been taking steroids in the previous two months should receive corticosteroids as during exacerbation (e.g., prednisone 1 mg · kg−1 · day−1) [30]. There is no need for perioperative supplemental doses of steroids as inhaled steroids alone do not cause adrenal suppression [31].

Finally, a child with “difficult” asthma who regularly takes bronchodilators and/or corticosteroids may require an intensification of the frequency of bronchodilators, an increase in the dosage of corticosteroids, or occasionally all these measures [28].



4.3 Bronchopulmonary Dysplasia (BPD)


Bronchopulmonary dysplasia (BPD) is the most common cause of chronic lung disease in infants.

It mostly affects premature infants weighting about 1000 g at birth that still need oxygen therapy for more than 28 days and after the 36 gestational week [32, 33].

Northway first described BPD in 1967 in a group of infants with respiratory failure after prolonged mechanical ventilation and administration of high concentrations of oxygen [33]. The lung of these infants presented emphysema, atelectasis, fibrosis, epithelial metaplasia, and marked hypertrophy of smooth muscles in the airways and pulmonary vessels.

The uses of less aggressive ventilation modes and postnatal surfactant therapy have significantly reduced the severity of respiratory distress syndrome and, consequently, the severity of BPD. Actually BDP is characterized mainly by pulmonary inflammation a decrease of the process of septation of the alveoli and an alteration in vascular development [3436], with a framework characterized by diffused X-ray opacity [37].

The triad airway obstruction, bronchial hyperreactivity, and lung hyperinflation determine inhomogeneous distribution of ventilation, reduced compliance, increased work of breathing, and gas exchange impairment [38]. The clinical manifestations of BPD are tachypnea, wheezing, coughing, frequent febrile episodes, episodes of desaturation, and bradycardia [38, 39].

Patients with BPD have high respiratory resistance, decreased lung volumes, lower functional residual capacity, airway obstruction, and lung hyperinflation. During the first year of life, infants with BPD are at increased risk of laryngospasm, bronchospasm, and desaturation due to bronchial hyperreactivity. Moreover bronchial secretions may lead to occlusion of the endotracheal tube. Finally, in the presence of hypothermia, pain, acidosis, or hypoxia, infants with BPD may develop pulmonary hypertension resulting in pulmonary hypoperfusion, hypoxemia, and cardiac failure [40].

These respiratory alterations are mostly evident during the first 3 years of life. After 5–8 years infants with a medium form of severe BPD can be asymptomatic, while the airway’s hyperresponsiveness may persist.

Nutritional support and therapy with bronchodilators, antibiotics, diuretics, and corticosteroids should be optimized before surgery [40]. Preoperative echocardiography is recommended, in order to assess cardiac contractility and the presence of an associated right ventricular dysfunction [37, 40]. If a BPD patient is taking diuretics, the concentration of electrolytes should be evaluated before surgery [40].

Patients with BPD may require monitoring and ventilation up to 24–48 hours after surgery. The risks of general anesthesia with intubation in infants with BPD may possibly be reduced or prevented by the use of regional anesthesia techniques and/or with the use of a laryngeal mask airway (LMA) [19, 41].


4.4 Allergies


In most industrialized countries, the immediate hypersensitive reactions to anesthetics and drugs used in the perioperative period are being reported with increasing frequency. Muscle relaxants and latex are the two main causes responsible for these intraoperative allergic events [42, 43]. In most cases, the reactions are of immunologic origin (IgE-mediated reactions, anaphylactic reactions) or due to the direct stimulation of histamine release (anaphylactoid reactions) [44, 45].

The clinical history may reveal a history of atopy and allergy to medications, to latex, or to tropical fruits.

Atopy is a hereditary predisposition in which the patient synthesizes IgE antibodies to various allergens: pollen, dust, animal hair, and foods. Clinically it presents with asthma, allergic rhinitis, conjunctivitis, fever, and eczema [46]. Gualdagen H et al. suggested an association between anaphylactic shock during anesthesia and atopy. The basophils of atopic patients easily release histamine [47]. Atopy may be a risk factor when drugs that induce histamine release (atracurium, mivacurium, etc.) are injected rapidly.

An unexplained episode characterized by cardiovascular collapse, bronchospasm, and edema, during a previous anesthesia, could be interpreted as an allergic reaction. Allergy to local anesthetics is quite exceptional. In a series of 208 patients who had a suspected reaction to local anesthetics, IgE-mediated mechanism was demonstrated in only four cases. In other patients, the causes were vasovagal phenomena, possible reactions to additives, panic episodes, or intervascular injection of adrenaline [48]. There is a high incidence of cross-reactions between neuromuscular-blocking agents. It is recommended to avoid administering neuromuscular-blocking agents to patients with previous allergic reactions to this class of drugs before an allergy test has been performed.

Preoperative identification of patients at risk is the first element of prevention against latex allergy. In the operating room, the main objective is to ensure the patient at risk avoids coming in contact with latex, for, e.g., the gloves. The prevention of this contact and/or the repeated exposure to latex is the cornerstone in preventing patients from developing anaphylaxis during surgery[4953].

The incidence of latex allergy in the pediatric population varies from 0.8 to 6.7 % (Table 4.2). Common features of groups at risk of presenting an allergic reaction are atopy, early contact with latex (within the first year of life), and the frequent and prolonged exposure to latex [54, 55]. An allergy skin tests with specific IgE + before surgery could be justified in [56]:


Table 4.2
Groups of patients at risk for developing latex allergy





































Group

Incidence %

Spina bifida [87, 88]

18–72

Urogenital tract malformations [89]

17–71

Repeated gastrointestinal tract surgery [90, 91]

17–20

Extensive or repeated neurosurgical procedures [92]

36

More than five surgical procedures at neonatal stage or before the age of one [93]

55

Atopic subject [49]

9–36

Tetraplegic patients

a

History of anaphylactic reaction of unknown etiology [94]

a

Allergy to fruits and vegetables, especially the tropical variant [95]

35–55


aNumerous case reports with no objective definition of a percentage than the general population




  • Patients with a documented allergy to an anesthetic drugs or latex


  • Patients with a history of unexplained reactions during general anesthesia (i.e., severe hypotension, bronchospasm, edema)


  • Patients who claim to have an allergy toward local anesthetics


  • Patients who belong to a group at high risk for latex allergy (Table 4.2)

The skin prick test (SPT) remains the gold standard for IgE-mediated reactions evaluation. To prevent a false-negative result due to the depletion of mast cells, STP should be performed 6 weeks after an acute allergic event. The sensitivity to latex is 70–100 % and specificity of 74–100 %. Muscle relaxant allergy sensitivity is greater than 95 %, and specificity is still a matter of debate [52, 57]:

The radioallergosorbent test (RAST) is an in vitro-specific IgE test and is currently restricted to the diagnosis of anaphylaxis to muscle relaxants, thiopental, or latex. The RAST sensitivity to latex varies between 53 and 97 % with specificity of 33–87 %. The RAST specificity may not exclude a false-negative case of latex sensitization. Nevertheless, because of the absence of the risk of anaphylaxis and the simplicity of execution, the RAST is one of the most widely used test. Some studies report that serum levels of IgE are well correlated with the number of surgeries. The patient is considered sensitized if the IgE antibody concentrations of > 0:35 kU / L [54, 58].

Some studies support the prophylaxis with diphenhydramine, cimetidine, and methylprednisolone [18, 54]. Pharmacological prophylaxis may only mitigate early immune response or may not prevent anaphylaxis at all [58, 59]. However, there is no evidence to support the use of pharmacological premedication [60].

The term latex-safe defines a path that must be applied to patient with latex allergy during the perioperative period. Latex-safe strategies designed to prevent patients at risk to be in contact with latex must be a priority of health-care facilities [49, 54, 61]. The term latex-free defines an instrument or tool in which the manufacturer certifies the absolute absence of latex [60].

If the patient presented a severe allergic reaction of unknown origin, characterized by unexplained hypotension or circulatory collapse, bronchospasm, and edema during a previous general anesthesia, it is recommended to adopt a latex-safe environment with a regional anesthesia technique or general anesthesia without neuromuscular-blocking drugs [46, 62].


4.5 Heart Murmurs


Heart murmurs are a common finding in childhood, and about 50–72 % of these murmurs are normal or innocents [63, 64]. Every child with a heart murmur requires a thorough clinical examination with assessment of peripheral pulses, blood pressure, and SaO2, ECG, and in selected cases an echocardiography [6567].

The anamnesis should look for history of prematurity, the presence of congenital malformations, respiratory symptoms including repeated infections, cyanosis, chest pain, syncope, or family history of sudden death. Table 4.3 includes some useful questions to determine the clinical effect of a murmur [68].


Table 4.3
Evaluation of the clinical effects a murmur [68]



























Children

 Does he/she run? Like peers?

 Is he/she calmer or slower than peers?

Cyanosis

 Does he/she turn blue? During feeding/when crying?

 Does he/she lose consciousness?

 Does he/she stop playing and squat?

Infant

 Is feeding prolonged?

 Does he/she sweat during normal care?

 Does he/she have swollen eyes in the morning?

The physical examination includes auscultation of the heart, both when supine or sitting, as the intensity of an innocent murmur increases in the supine position for increased end-diastolic volume and stroke volume. The intensity of the most of the pathological murmurs doesn’t vary during changes on the patient position. The only exception is the murmur of the hypertrophic cardiomyopathy (HCM), which increases in intensity from supine to sitting position [69]. Table 4.4 shows the characteristics of innocent murmurs and pathological ones [64, 65, 70].


Table 4.4
Characteristics of innocent murmurs and pathological ones [64, 65, 70]
















Murmur

Characteristics

Innocent

Systolic or a continuous

Increases and decreases

Mild or moderately mild (2/6 or less)

Increase in intensity from sitting to supine position

Pathological

Diastolic, pansystolic, or late systolic

Generally intense (3/6 or more)

Associated with tremors

Associated with signs or symptoms of heart disease

Does not vary significantly going from sitting to supine position (except CMI murmur)

Both arms’ brachial pulses in infants or radial pulses in children should be examined and compared with femoral pulses. Small femoral pulses, especially if discrepant with respect to the quality of brachial or radial or associated with radio-femoral delay, are suggestive of aortic coarctation or aortic arch obstruction and require further investigation [66].

The value of ECG and chest radiography in the diagnosis of congenital heart disease is limited. Both tests have a very low sensitivity and specificity. Chest X-rays also expose the child to ionizing radiation and its routine application can be defined as inappropriate in an asymptomatic child [7173].

ECG has a low sensitivity in identifying congenital heart lesions in children with asymptomatic heart murmur.

Echocardiography remains the gold standard for diagnosis of congenital heart disease and its role in the diagnosis of asymptomatic murmurs has changed radically in the last 10 years. In the presence of a murmur, it is recommended to perform an echocardiogram if [6567]:



  • The child is less than 1 year old.


  • The murmur has the characteristics of a pathological murmur.


  • Signs and symptoms of heart disease are presented.


  • There is evidence on the ECG of right or left hypertrophy.

Nonurgent surgery in infants under 1 year of age, with pathological murmur, and/or signs and symptoms of congenital heart disease, and/or ECG with evidence of right or left hypertrophy, should be delayed until an echocardiogram with a cardiology consultation identifies or excludes a pathological condition [64, 68].


4.6 Vaccination


Vaccination represents the most efficient and reliable prevention of primary infectious diseases [74].

Anesthesia and surgery may interfere with the immune response [7577]. However, the immune-modulatory effect of general anesthesia and surgery may not modify the efficacy of recently given vaccine [31, 7881].

Adverse effects to vaccines can occur on the day of administration during the following 90 days [82]. The most common complications of vaccination (fever, malaise, crying, pain) can be wrongly interpreted as particularly infectious complications after surgery. Then there are two questions that need to be answered [81]:

1.

Should vaccination be postponed in children scheduled for surgery?

 

2.

Should anesthesia be postponed in recently vaccinated children?

 

There are no clear answers to these questions [83]. The Italian Schedule of Vaccination from Ministry of Health did not provide recommendations regarding anesthesia or surgery [74]. The handbook on vaccinations of Great Britain states that “anesthesia and surgery are not contraindications to routine immunization but in some of these situations, additional precautions may be required” like in case of asplenia or splenic dysfunction [84]. The Australian handbook on vaccinations specifies “that surgery should be postponed for a week after an inactivated vaccine and three weeks after a live attenuated vaccine”. A vaccination should be postponed for a week after an operation under general anesthesia [85]. The Ministry of Health of New Zealand stated that “there is no evidence that anesthetic reduces the immune response to a vaccine or increases the risk of adverse events following immunization (AEFI).”

Immunization with inactive vaccines should be avoided for 3 days prior to an anesthetic (12 days for a live vaccine such as MMR) in case an AEFI occurs and results in the postponement of the anesthetic [86].

It seems reasonable to accept that there is a risk, albeit vague and theoretical, associated with anesthesia in recently vaccinated children. This small risk can be reduced to zero by ensuring that surgery, anesthesia, and vaccinations do not coincide. The following has been recommended [83]:
Sep 22, 2016 | Posted by in ANESTHESIA | Comments Off on Preoperative Consideration in Common Pathological and Nonpathological Conditions

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