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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4597_Библиотеки_им_академика_М_И_Перельмана.pdf
Tracheostomies
12
might require bronchoscopic pulmonary toilette after admission (e.g., due to
chronic obstructive pulmonary disease or airway burns), consider increasing to
a 9.0-mm ID tube for men or an 8.0-mm ID tube for women.
■
It is physiologically important to note that the upper part of the trachea
is extrathoracic, whereas the lower half is intrathoracic. This relationship creates different behaviors during inspiration and expiration. The
extrathoracic trachea, which is subject to the effects of ambient atmospheric pressure, decreases slightly in caliber during inspiration and
increases during expiration. By contrast, the intrathoracic trachea undergoes expansion during inspiration as a result of negative intrathoracic pressure transmitted from the pleural cavity. During expiration,
however, surrounding pleural pressure diminishes the tracheal caliber,
which may be exaggerated in the setting of marked increased expiratory
effort in airway obstruction.
■
Forces affecting airflow through the airways can be categorized as those
that facilitate airflow and those that oppose it. In general, differences in
pressure drive airflow in and out of the respiratory system from areas
of higher to lower pressure. The lung contains two different pressure
systems, whereas the chest wall exerts a separate one. The force driving
airflow is the difference between the airway opening, or mouth (Pm), and
the pressure in the alveoli (Palv) and the pleural space (Ppl). The difference between these two pressures is called the transpulmonary pressure
(PL, the pressure across the lung). The pressure across the chest wall
(Pcw) is the difference between the pleural pressure (Ppl) and the atmospheric pressure (PB) (see Table 1.1).
■
Forces opposing airflow in the airways result from elastic, flow resistive,
or inertial properties of the respiratory system. Collectively, they result
in pressure drops across the respiratory system. Inertance deals with the
mass of the lung and the acceleration of these tissues and the linear acceleration of gas in the lung. Thus, pressure losses due to inertial forces increase progressively as respiratory frequency increases but are generally
Pressure Differences Across the
1.1
Airway (Paw) Palv – Pm
Lung (PL) Palv – Ppl
Chest wall (Pcw) Ppl – PB
Total respiratory system (PRS) Palv – PB
Paw: airway pressure; Palv: pressure in alveolar spaces; PB: atmospheric pressure; Pcw: pressure
of the chest wall; PL: lung pressure; Ppl: intrapleural pressure (estimated at esophageal pressure);
Pm: mouth pressure (or airway opening); PRS: total pressure within the respiratory system.
Respiratory System
Chapter 1 Functional Anatomy of the Airway
negligible during quiet breathing. Elastance, and its reciprocal compliance, reflect the relationship between pressure and volume when there
is no airflow. Hence, these measures are static. By contrast, resistance is
dependent on the rate of changes of lung volume (i.e., flow) during active
breathing and are, thus, dynamic pressures.
Comparative Anatomy of the Adult and Infant Airways
The anatomical differences between the adult and infant airways include the
position and shape of the larynx, tongue, epiglottis, and bronchi (see Figure 1.5).
In proportion to the rest of the body, the infant’s head is much larger than the
adult’s, so its weight forces the cervical spine to assume a more flexed position,
which easily produces airway obstruction. The infant’s tongue is proportionately larger than that of the adult’s and with lack of muscle tone may “fall back,”
obstructing the flow of air during inspiration and expiration. Furthermore, the
epiglottis is omega shaped, longer, and stiffer.
13
1.5
Comparative
anatomy of adult
and infant airways.
Tracheostomies
14
infants. At birth, the rima glottidis lies at the level of the interspace between the
third and fourth cervical vertebrae. Upon reaching adulthood, it lies one vertebra lower. The narrowest part of the infant’s laryngeal airway is at the level of
the cricoid cartilage, whereas that of the adult is at the rima glottidis. At age 8,
the larynx of the child closely resembles that of the adult except in size. The infant’s vocal cords are concave and lie more horizontally. The biggest difference
between the adult and infant larynx is that the overall diameter of the adult’s
airway is 10 to 12 mm wider than that of the newborn. If the internal diameter
of a neonate’s larynx is 4 mm at the level of the cricoid cartilage, a 1-mm circumferential reduction in this diameter (caused by either trauma or infection)
would reduce the overall cross-sectional area of the airway by approximately
75%. A similar reduction in the diameter of the adult airway would reduce the
cross-sectional area by about 44%.
leaving less room for error in positioning endotracheal tubes. The trachea of
a premature infant may be as short as 2 cm. In infants, the bifurcation of the
trachea (into right and left mainstem bronchi) projects at an angle of about
30 degrees from tracheal axis, whereas the angle of the left mainstem bronchus
and tracheal axis is more acute. Thus, in infants the right mainstem bronchus is
less vertical than in adults (Morris, 1988).
The larynx is situated at a higher level in relation to the cervical spine in
The major conducting airways are both narrower and shorter in infants,
Conclusion
Functional anatomy is important to understand when treating the patient with
a tracheostomy tube. Paying attention to the nuances of anatomy in relation
to technique will often mean the difference between success and failure in
tracheostomy tube placement as well as removal and the host of day-to-day
functions (respiratory, swallowing, and vocalization) in between. A clear understanding of the relevant anatomical structures, their blood supply, and their
innervation will enhance understanding of this interdependent relationship. A
study of the airway’s functional anatomy will also guide the best approaches for
instrumentation and intervention with each patient. It also provides a basis for
understanding how complications are best avoided or, if they occur, how they
may be detected.
Key Points
The upper airway provides a natural conduit for gas exchange, it humidi- ■
fies and protects the lower airway and participates in the functions of
deglutition and phonation.
■
Alteration of pharyngeal anatomy may lead to the development of obstructive sleep apnea (OSA) and upper airway obstruction.
■
The larynx is the organ of phonation. Disruption of its highly innervated
structure immediately interferes with upper airway patency and, thus,
impedes respiration.
Chapter 1 Functional Anatomy of the Airway
Deglutition and phonation are highly coordinated processes between ■
several structures of the upper airway and gastrointestinal tracts, and
are dependent on intact sensory and motor innervation.
■
Pediatric airway anatomy varies from that of adult anatomy in the size
of the head, the position of the larynx, the shape of the epiglottis, the
angle of the mainstem bronchi, and, most importantly, the diameter of
the upper airway.
References
Ayappa, I., & Rapoport, D. M. (2003). The upper airway in sleep: Physiology of the pharynx.
Sleep Medicine Review, 7, 9.
Ellis, H., & Feldman, S. (1993). Anatomy for anaesthetists (6th ed.). Oxford, England: Blackwell
Scientific.
Grande, C. M., Ramanathan, S., & Turndorf, H. (1988). The structural correlates of airway func-
tion. Problems in Anesthesia, 2, 175–182.
Haponik, E. F., Smith, P. L., Bohlman, M. E., Allen, R. P., Goldman, S. M., & Bleecker, E. R.
(1983). Computerized tomography in obstructive sleep apnea: Correlation of airway size
with physiology during sleep and wakefulness. American Review of Respiratory Diseases,
127, 221.
Morris, I. R. (1988). Functional anatomy of the airway. Emergency Medicine Clinics of North
America, 6, 639–669.
Redden, R. J. (2000). Anatomic considerations in anesthesia. In C. A. Hagberg (Ed.), Handbook
of difficult airway management (pp. 1–13). Philadelphia, PA: Churchill Livingstone.
Schwab, R. J., Gefner, W. B., Pack, A. L., & Hoffman, E. A. (1993). Dynamic imaging of the upper
airway in normal subjects. Journal of Applied Physiology, 74(4), 1504.
Shorten, G. D., Opie, N. J., Graziotti, P., Morris, I., & Khangure, M. (1994). Assessment of upper
airway anatomy in awake, sedated, and anaesthetized patients using magnetic resonance
imaging. Anaesthesia and Intensive Care, 22, 165.
15
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Tracheotomy
Procedure
Michiel J. Bové and
M. Sherif Afi fi
2
Despite being one of the more common surgical procedures, tracheotomy can
be one of the most challenging because of the medical complexities presented
by many patients requiring it. Anatomical limitations make the trachea difficult
to assess in certain patients, and emergent situations and nonoperative settings
provide less than ideal circumstances.
Tracheotomy was first described nearly 3,500 years ago, making it one of
the earliest recorded surgical procedures. Alexander the Great was alleged to
have carried out a tracheotomy in the fourth century .. (Frost, 1976). The first
successful tracheotomy is attributed to Antonio Musa Brasavola, who published
his account of the procedure in 1546 .. The initial indications for the procedure were limited to life-threatening airway obstruction, and associated rates of
mortality were therefore extremely high. The eventual expansion of its indications as well as the standardization of its methods produced wider acceptance
of the procedure. Chevalier Jackson’s description of his modifications to the
procedure, published in 1909, improved its efficiency and safety and reduced
the mortality of tracheotomy from 25% to less than 2%. This improved procedure also reduced the incidence of tracheal stenosis, particularly in children.
17
Tracheostomies
18
Jackson’s systematic analysis led him to recognize the importance of several
factors, including avoiding too high an incision or dividing the cricoid cartilage,
using an appropriate cannula, and providing appropriate postoperative care.
Indications for Tracheotomy
The indications for tracheotomy placement in the adult population can be
grouped into four broad categories: A tracheotomy can be performed to relieve
a mechanical obstruction, manage aspiration and promote bronchial hygiene
maneuvers, provide long-term ventilation (while avoiding the long-term complications of translaryngeal intubation), and promote weaning from mechanical ventilator support. The indications for tracheotomy were recently defined
by the American Academy of Otolaryngology—Head and Neck Surgery in the
Clinical Indicators Compendium (2009) seen in Table 2.1.
sideration of multiple factors is necessary to ensure optimal patient outcome.
Relevant factors include the relative risk of tracheotomy versus alternative
means of providing an artificial airway, characteristics of the patient’s respiratory anatomy and physiology, the patient’s specific pathologic process and prognosis, available institutional facilities, and skilled personnel.
endotracheal intubation while other prioritized supportive care is provided. Angioneurotic edema, temporary bilateral vocal cord paralysis, and epi glottitis are
examples of acute airway obstruction in which temporary orotracheal intubation usually obviates the need for a surgical airway. Alternatively, if planned
interventions such as radiation therapy or surgery predict airway obstruction,
a tracheotomy can be performed prior to treatment to protect the airway. Tracheotomy is also frequently performed as part of head and neck surgical procedures involving free tissue transfer reconstruction in the oral cavity, oropharynx,
hypo pharynx, or larynx. In these cases, postsurgical edema may be deleterious
The decision to perform a tracheotomy remains complex; however, a con-
Whenever possible, acute upper airway obstruction should be managed with
Indications for Tracheotomy as Defined by the
American Academy of Otolaryngology—Head
and Neck Surgery in the Clinical Indicators
2.1
1. Prolonged or expected prolonged intubation
2. Inability of patient to manage secretions
3. Facilitation of ventilation support
4. Inability to intubate
5. Adjunct to manage head and neck surgery
6. Adjunct to manage significant head and neck trauma
Compendium
Chapter 2 Tracheotomy Procedure
to the viability of the newly placed flap and may lead to obstruction and reintubation because of altered anatomy.
Tracheotomy may be necessary in cases of laryngotracheal trauma, facial
trauma, obstructing upper aero-digestive tract neoplasm, or even severe angioneurotic edema, in which intubation may not be technically feasible. Rarely,
tra cheotomy is used in severe cases of obstructive sleep apnea where medical treatments have failed and other forms of surgical correction are not
ap propriate.
Timing of Tracheotomy
The decision about the most appropriate time to perform a tracheotomy should
balance the likelihood of laryngeal injury due to the continued use of an endotracheal tube versus the likelihood of surgical or stoma-related complications
following tracheotomy (see Table 2.2) (Stone & Bogdonoff, 1992).
There is no convincing evidence that endotracheal intubation should be
limited to a specific time frame to prevent laryngeal dysfunction. However,
many clinicians believe only patients who are unstable or unlikely to benefit
from tracheotomy should be ventilated via an endotracheal tube for more than
21 days (Heffner, 1993; Plummer & Gracey, 1989). Part of the rationale is that
tracheotomy improves patient comfort and communication and enhances nursing care (Bishop, 1989). A multicenter international study of 1,638 patients found
that tracheotomy was performed after a median of 11 days, suggesting this view
is widespread (Esteban et al., 2000).
19
Comparison of Tracheotomy and
2.2
Tracheotomy Endotracheal Intubation
Reduced need for sedation ■
Reduced damage to glottis ■
Reduced work of breathing ■
(by reducing dead space)
Reduced patient discomfort
■
More invasive and complicated compared ■
with endotracheal tube placement
Scar formation
■
Tracheotomy site can bleed or become ■
infected
Requires skill to perform the procedure
■
May be associated with long-term ■
complications (e.g., swallowing difficulties)
Endotracheal Intubation
Easier and quicker to perform com- ■
pared with tracheotomy
Tolerated well for short periods
■
Weaning more difficult after long- ■
term placement
Requires sedation
■
Prevents aspiration of secretions ■
Can be used to give certain medica- ■
tions (e.g., adrenalin)
Need to warm and filter gases as the
■
nose, which would normally provide
this function, is bypassed
Improper placement can occur (e.g.,
■
esophageal placement)
Tracheostomies
20
domized trial, Rumbak and co-investigators (2004) compared early tracheotomy
(within 48 hours) to late tracheotomy (14 to 16 days) in 122 medical patients
with respiratory failure who were expected to require mechanical ventilation for
more than 14 days. They found the early group had significantly decreased mortality (31.7% versus 61.7%), incidence of hospital-acquired pneumonia (5% versus
25%), length of intensive care unit (ICU) stay (4.8 versus 16.2 days), and duration
of mechanical ventilation (7.6 versus 17.4 days). In a meta-analysis of five studies (406 patients), Griffiths, Barber, Morgan, and Young (2005) found that early
tracheotomy (within 7 days) was associated with a shorter duration of mechanical ventilation as well as a shorter length of ICU stay. In a retrospective cohort
study of more than 10,000 tracheotomy patients, Scales, Thiruchelvam, Kiss, and
Redelmeier (2008) compared those who underwent early tracheotomy (within
10 days) with those who underwent late tracheotomy (after 10 days). The early
tracheotomy group had more ventilator-free days and a significant reduction
in 90-day mortality (34.8% versus 36.9%), 1-year mortality (46.5% versus 49.8%),
and study mortality (63.9% versus 67.2%). Better outcomes were associated with
early tracheotomy in all of the diagnostic subgroups except for patients with a
history of cardiac disease, in whom early tracheotomy was associated with an
increased risk of death at 90 days (relative risk 0.135, 95% CI 0.003–0.285).
study of 54 male veterans found that laryngeal pathology was significantly worse
among patients who had undergone a tracheotomy 24 hours previously compared to patients who were extubated without a tracheotomy (Colice, Stukel, &
Dain, 1989). There was no association between severe laryngeal complications
and duration of endotracheal intubation in this study.
tients requiring prolonged intubation were randomized to early tracheotomy
(within 4 days) versus prolonged intubation. There were no significant differences in any clinical outcome, including mortality, incidence of pneumonia acquired in the ICU, number of ventilator-free days, time in ICU, number of septic
episodes, sedation requirement, and laryngeal or tracheal complications. The
trial was underpowered, however, since it was terminated early due to poor
recruitment.
mechanical ventilation) appears appropriate for patients for whom weaning
and extubation are not likely before day 14, provided the patient is stable. For
those patients for whom early tracheotomy is not chosen, a daily evaluation
of the probability that mechanical ventilator support will be needed beyond
21 days should determine the timing of tracheotomy as long as the patient is
stable and benefits are anticipated.
Early tracheotomy has been supported by a number of studies. In a ran-
Other studies argue against early tracheotomy, however. One observational
In a prospective, randomized study by Blot and coauthors (2008), 123 pa-
Taking these data together, early tracheotomy (i.e., within 7 to 10 days of
Preoperative Management
The patient with an unstable airway represents the most acute of medical emergencies. Proper management requires the coordinated mobilization of a welltrained team of physicians, nurses, and respiratory care practitioners. Initial
intervention, if feasible, should be via orotracheal intubation or rigid bronchoscopy. If these modalities are contraindicated or not possible, tracheotomy should
Chapter 2 Tracheotomy Procedure
be performed in the operating room where resources are readily available. In
elective situations, however—for the stable, intubated patient—open bedside
tracheotomy is performed more frequently in the ICU setting. Bedside tracheotomy has the advantages of decreased transport-related risks, operating room
cost, and schedule burden. Regardless of the setting, adequate lighting (especially headlights), suction, and assistance should be available. If possible, the
anesthesia team should be present during tracheotomy for intensive cardiovascular and respiratory monitoring, to assist with mechanical ventilation, and to
provide any necessary cardiopulmonary resuscitation. Frequently, patients with
chronic respiratory obstruction develop elevated carbon dioxide levels, leading
to loss of respiratory drive after the establishment of a surgical airway. Preoperative laboratory profiles, including coagulation, hemoglobin, and electrolytes, should be reviewed. Any abnormalities should be corrected and remain
stable prior to elective tracheotomy.
The patient should be optimally positioned and secured. The neck should
be extended (unless contraindicated) with a shoulder roll. For tracheotomies
performed in an emergency on patients in respiratory distress, optimal neck
extension is usually not tolerated, and the procedure is performed with the patient in the semi-Fowlers position. The patient’s face, neck, chest, and shoulders should be sterilized with prep solution. The patient’s face should not be
draped—both to allow easy access to the endotracheal tube as well as to avoid
the collection of flammable, oxygen-enriched vapors beneath the drapes. Further, the use of alcohol-based antiseptics calls for strict adherence to the proper
use of these substances, including observing the required drying time. It is also
recommended that whenever electrocautery or diathermy is used on the skin,
one of many aqueous-based antiseptics be used. If an alcohol-based antiseptic
is used, it should be cleaned off with a dry swab before the diathermy is used.
21
Anesthesia Management
Typically, patients presenting for tracheostomy are either intubated patients in
chronic respiratory failure, those suffering major trauma, or patients for whom
tracheostomy is part of a scheduled procedure (e.g., radical neck dissection).
Features of the history and physical exam that may be associated with a difficult
airway include: (a) specific anatomic characteristics (e.g., bull neck, large tongue,
receding jaw, limited mouth opening, difficulty visualizing posterior pharynx,
diminished cervical spine range of motion, and obesity); (b) either inspiratory
stridor (signifying obstruction at or above the level of the larynx) or expiratory stridor (signifying subglottic or intrathoracic obstruction); (c) hoarseness
(vocal cord lesion or dysfunction); (d) tachypnea; (e) marked respiratory effort;
(f ) dyspnea; (g) a previous history of thyroid gland or neck surgery, trauma, or
radiation therapy; (h) a history of previous difficult intubation or vocal cord
paralysis; and (i) infections such as epiglottitis or Ludwig’s angina (Nekhendzy,
Guta, & Champeau, 2009).
Preoperative Evaluation
Patients with respiratory insufficiency may require mechanical ventilation with
positive end-expiratory pressure (PEEP) to maintain adequate oxygenation.