الفهرس 
Anatomy and physiology of respiratory systemOnly 14 pages are availabe for public view
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Abstract
Respiratory emergencies represent an important part of acute
medicine in general. Respiratory emergencies also play a crucial part in
critical care medicine and constitute an important share of the numerous
problems in an intensive care unit.
Understanding the anatomy and normal physiology of respiratory
system is a must to understand the nature of respiratory diseases and
emergencies. Also it targets the management towards correction of the
pathology to the normal physiology and intact anatomy.
Respiratory emergencies can arise from an abnormality in any of the
components of the respiratory system, including the airways, alveoli,
pleura, pulmonary circulation, central nervous system, peripheral nervous
system, respiratory muscles and chest wall.
Evaluation of patients admitted to ICU with respiratory problem is
often a challenge, since the differential diagnosis is a broad. So making
correct diagnosis by proper evaluation of clinical status, understanding
the significance of the tests of pulmonary function and the pulmonary
imaging studies is essential.
General and local examinations are very important because
symptoms and signs present during respiratory emergencies vary
according to the underlying pathology.
Most common symptoms occurs in respiratory emergencies are
cough, expectoration, haemptysis, dypsnea and chest pain.
Signs of respiratory emergencies can include pulmonary signs such
as tachypnea, cyanosis, hypoxemia, hypercapnia and pulmonary odema. Also signs of respiratory emergencies can include extrapulmonary signs
such as perfuse sweating, confusion, tachycardia and fever.
Monitoring plays an important role in the current management of
patients in respiratory emergency but sometimes lacks definition
regarding which signals and derived variables should be prioritized as
well as specifics related to timing (continuous versus intermittent) and
modality (static versus dynamic).
Many new techniques of respiratory monitoring have been made
available for clinical use recently, but their place is not always well
defined. Appropriate use of available monitoring techniques and correct
interpretation of the data provided can help improve our understanding of
the disease processes involved and the effects of clinical interventions.
Measures used to monitor patients in respiratory emergencies
include monitoring of gas exchange, respiratory mechanics, lung
volumes, hemodynamic and Bronchoalveolar lavage studies.
Gas exchange monitoring measures are usage of pulse oximetry,
transcutaneous carbon dioxide monitoring, volumetric capnography use,
dead space calculation and assessment of extravascular lung water.
Respiratory mechanics monitoring measures are compliance and
resistance assessment, study of Pressure/volume curves, assessment of
diaphragmatic function, Pressure and flow monitoring, assessment of
work of breathing, measurements of occlusion pressure, assessment of
pressure-time product, assessment of transpulmonary pressure and
abdominal pressure.Lung volumes monitoring measures are direct measurement of
end-expiratory lung volume, usage of chest ultrasonography,
computed tomography and electrical bioimpedance tomography.
Respiratory emergencies support encompasses a lot of prophylactic,
therapeutic and diagnostic interventions. The application of correct
modality at appreciate time will often result in good outcome with
minimal risks and avoid the use of more invasive or expensive supportive
measures.
Access to free airways is the first consideration in respiratory
emergencies and represents an important part of acute medicine in
general.
Difficulties or failure in airway management are still important
factors in morbidity and mortality related to intensive care.
Practice guidelines have been established to aid management of the
difficult airway and to reduce poor outcomes and several algorithms have
been developed.
After securing airway attention must be directed to treat hypoxemia
which is the major immediate threat to organs function. Therefore, the
first objective in the management of respiratory emergencies is to reverse
and/or prevent tissue hypoxia by maintaining PaO2 at the level of 60 mm
Hg and SaO2 > 88%.
Measures to improve oxygenation to counteract effect of
hypoxemia are variable and should be individualized according to the
patient condition.
Those measures include oxygen therapy, variant ventialtory
strategies such as noninvasive ventilation, low tidal volume ventilation, liquid ventilation, inverse ventilation ratio, permissive
hypercapnia, prone position, open lung strategy, airway realse
pressure, high frequency oscillatory ventilation and extracorporeal life
support.
Also many medications could be used during respiratory
emergencies helping to improve oxygenation and ventilation such as
corticosteroids, nitric oxide, bronchodilators and central respiratory
stimulants.