الفهرس 
Physiological changes occurring during Pregnancy affecting on respiration.Only 14 pages are availabe for public view
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Abstract
Respiratory problems are common in pregnancy and it is worth noting that in the maternal deaths during the period from (1994–96), 53.7% of direct deaths were as a result of respiratory problems excluding seven other deaths from indirect causes (Ware and Matthay, 2005).
Acute respiratory failure during pregnancy, although relatively uncommon, continues to be a prominent cause of maternal mortality, accounting for 30% of maternal deaths and is the most common reason for admission to the intensive care unit (ICU) of critically ill obstetric patients. Pregnancy results in many changes to the female body which makes it more susceptible to respiratory complications For example, a decrease in T-helper cells results in a state of relative immunosuppression. Although the incidence of infections is not increased during pregnancy, complications from some infections, such as certain types of pneumonia, are increased (Drenthen et al., 2005).
Hypercoagulability associated with pregnancy results in a marked increase in the incidence of thromboembolic disease. Although rare, pregnancy may be associated with other embolic phenomena, including amniotic fluid embolism, air embolism and trophoblastic embolism. Since there is an increase in intravascular volume and cardiac output during pregnancy, females with underlying cardiac disease may present with acute pulmonary oedema (Resnik et al., 2005).
The course of certain pulmonary diseases, such as bronchial asthma, may also worsen during pregnancy, causing respiratory failure. The outcome of pregnancies complicated by acute respiratory failure is not predicted by the aetiology of respiratory failure; however, patients presenting with a low arterial blood pH, initial loss of consciousness, disseminated intravascular coagulation and sepsis may be at higher risk of mortality, based on the results of one study (Dahlen, 2001).
Pregnancy of itself does not seem to increase mortality beyond that expected from the severity of the presenting illness. In general, pregnant patients with acute respiratory failure are treated similarly to the non pregnant patient with the same illness (Richard et al., 2003).
The most frequent indications for mechanical ventilation among obstetric patients admitted to an ICU are acute respiratory failure and hemodynamic failure, followed by impaired consciousness and postoperative ventilation (George et al., 2001).
Pulmonary oedema during pregnancy remains a significant cause of obstetric morbidity and mortality. The cardiopulmonary changes of pregnancy predispose subjects to greater likelihood of pulmonary oedema. In addition to the cardiac output and circulating blood volume changes; the plasma protein osmotic pressure gradually decreases by 20% during pregnancy, followed by a further 30% reduction during the post-partum period. Therefore, coupled with the decrease in the plasma osmotic pressure, small changes in hydrostatic can lead to pulmonary oedema (Sciscione et al., 2003).
Asthma is one of the most common medical conditions that can complicate pregnancy.The prevalence of asthma in pregnancy in the USA is estimated to be 3.7–8.4% ,and it affects 200,000–376,000 pregnancies annually. Episodes of acute asthma requiring emergency department visits or hospitalization have been reported in 9–11% of pregnant subjects managed by asthma specialists. Pregnancy can affect the course of asthma, and asthma can affect pregnancy outcomes (Elkyam et al., 2001).
VTE is a significant cause of morbidity and mortality during pregnancy, and occurs approximately five times more frequently in pregnant than in non pregnant females of similar age (Clark et al., 2008).