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Journal of the Chinese Medical Association 75 (2012) 95e96
www.jcma-online.com
Editorial
Risk factors of hypoxia during flexible bronchoscopy use in infants
A Japanese, Shigeto Ikeda, invented the flexible bronchoscope (FB) in 1966; the FB was introduced into clinical
practice due to its diagnostic accuracy, safety, and ease of use.1
Currently, the FB is one of the most important tools for
diagnosis and treatment of pulmonary diseases in child and
infants. The tendency to subdivide bronchoscopes into adult
and pediatric categories depending on their outer diameters is
arbitrary. The more interventional procedures via FB that are
performed in the pediatric population depend on experience
and the situational need.2,3 The procedures can be easily
performed both in an outpatient setting and in patient service
under moderate sedation and local anesthesia. The dynamic
airway obstruction often is better assessed with a FB than
a rigid bronchoscope. The indications for fiberoptic bronchoscopy are broad and growing, including laryngomalacia,
bronchomalacia, tracheomalacia, and suspected airway problems (persistent stridor, foreign body aspiration, hoarseness,
unexplained inspiratory retraction, or unresolved pneumonia,
etc.). Therapeutic bronchoscopy with the standard flexible
bronchoscope has long been used for the removal of foreign
bodies and stent placement; bronchoscopy can also be used for
the relief of large airway obstruction.
FB is usually performed via the oral or the nasal route.4 The
need for sedation is to improve patient comfort and add to the
ease of the procedure for the bronchoscopist.5 Some studies
reported that 16% to 21% of physicians use general anesthesia
for FB.5,6 Intravenous preparations of various sedatives such as
diazepam, midazolam, lorazepam, morphine sulfate, fentanyl,
and hydrocodone have been used either singly or in combination based on bronchoscopist preference and the availability
of the drug.5 There are multiple techniques for flexible fiberoptic bronchoscopy. Options include awake versus general
anesthesia and oral versus nasal approaches. Options for local
anesthesia include topical anesthesia via a nebulizer, handheld
aerosol, or nerve blocks (laryngeal and/or glossopharyngeal
nerves) and direct administration of local anesthetic through
the bronchoscope. Options during general anesthesia include
spontaneous versus positive-pressure ventilation with or
without muscle relaxation. Inhalation, intravenous anesthetics,
or both can be used for anesthesia. Patients who have copious
secretions in the preoperative period should receive anticholinergic medication to ensure a dry field, which provides
optimal visualization with the FB.6,7 Lidocaine is the most
commonly used drug for local anesthetic agents.8
Soong and colleagues9 clearly demonstrate in this issue that
intravenous sedation with midazolam, ketamine, atropine, and
topical anesthesia of lidocaine offer a relatively wide margin
of safety with a rapid onset and sufficient duration of action to
allow the completion of most bronchoscopic procedures.
All FB procedures are performed observing universal
precautions. Following each procedure, the instrument is
thoroughly disinfected or sterilized according to the published
consensus statement.10 To ensure adequate oxygenation
(oxygen saturation >92%) and hemodynamic stability, pulse
oximetry, heart rate and blood pressure are monitored
throughout the procedure, the risks associated with interventional procedures can be significant. The majority of our
currently performed interventional procedures all strive to
maintain airway patency and reestablish normal gas exchange
or to reestablish the airway structure to as near normal as
possible. Pulse oximetry is a painless, cost-effective, and more
sensitive test rather than arterial blood gas analysis for hypoxia
evaluation. The British Thoracic Society recommends that all
patients undergoing FB should have pulse oximetry measured
and supplemental oxygen should be given to maintain the
arterial oxyhemoglobin saturation at or above 90%.2 However,
there is little mentioned in the literature about what method or
methods of supplemental oxygen could feasibly and efficiently
achieve the 90% arterial oxyhemoglobin saturation, especially in the infant age.3
Supplemental oxygen is routinely administered during FB
to minimize the risk of dangerous hypoxia. Nasal cannula
offers the simplest means of administering oxygen during
transnasal FB; as transnasal FB became popular, supplemental
oxygen was delivered by nasal cannula, which is placed either
in the nares or in the mouth.11 Schnapf12 reported 36 children
in the youngest age group, 6 to 12 months, who showed the
greatest drop in saturation when compared with the other
groups. A decline in arterial oxygen saturation was frequently
noted during FB in infants and children; the risk of desaturation is increased when the bronchoscope was positioned in
the mid-trachea. Harless and colleagues13 reported the efficacy
of nasal prongs placed in the mouth of 16 patients undergoing
transnasal FB. Weber and others14 conclude that nasal prongs
are as effective as an nasopharyngeal catheter in delivering
oxygen to children with a hypoxemia, and they are also safer
to use. Cost permitting, they are a more appropriate means of
oxygen delivery to children with hypoxemia and acute lower
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doi:10.1016/j.jcma.2011.12.010
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Editorial / Journal of the Chinese Medical Association 75 (2012) 95e96
respiratory tract infection in hospitals in developing countries.
Milman and colleagues15 reported the delivery of oxygen via
a pharyngeal catheter produced fewer episodes of hypoxemia
than nasal cannula or no oxygen supplementation.
There is a risk of hypoxia during FB, which may occur
through the combination of several mechanisms including
underlying disease, oversedation, airway suction removing
oxygen or decreasing lung volume, and increased ventilationperfusion mismatching by concomitant airway block and
spasm, bleeding, and instillation of fluids. Because oversedation can depress respiration and lead to hypoxemia,
FB-associated hypoxemia may persist for several hours after
the procedure; this necessitates the close monitoring of
patients during the recovery period. Significant hypoxemia can
usually be prevented by the administration of supplemental
oxygen during the procedure and recovery.11e15
The article by Soong and colleagues9 in this issue describes
75 infants in three groups of 25 infants; the infants were
randomly applied with three different oxygen delivery techniques (nasal cannula, nasal prongs, and nasopharyngeal
catheter) during and 30 minutes after the FB procedure. The
article illustrates that supplemental oxygen via nasopharyngeal
catheter is a a simple and cost-effective method to maintain
good oxyhemoglobin saturation during FB examination in
infants.9
In conclusion, a decline of oxyhemoglobin saturation is
frequently noted during FB examination in infants. The risk of
desaturation is increased when the FB is located in the central
airway of pharynx and carina, and it can be successfully
managed by using supplemental oxygen. Nasopharyngeal
catheter could be a simple and cost-effective method for
supplementing of oxygen.
Shu-Jen Chen
Ren-Bin Tang*
Department of Pediatrics,
Taipei Veterans General Hospital, and National Yang-Ming
University School of Medicine,
Taipei, Taiwan, ROC
*Corresponding author. Dr. Ren-Bin Tang,
Department of Pediatrics, Taipei Veterans General Hospital,
201, Section 2, Shih-Pai Road,
Taipei 112, Taiwan, ROC.
E-mail address: [email protected] (R.-B. Tang)
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