Disorders of the respiratory system Flashcards
Respiratory conditions that may affect pregnant women
- asthma
- respiratory infections [influenza, chicken pox, tuberculosis]
- pnemonia
- pulmonary edema
- cystic fibrosis
- sarcoidosis
- pulmonary embolism
- acute chest syndrome in sickle cell crisis
physiological changes that affect the respiratory system in pregnancy
- respiratory rate slightly increases/stays the same at around 12-15 breaths per minute at rest
- increased vulnerability to pulmonary edema due to changes in oncotic pressure
- increased edema of the upper airway. nasal congestion that can make intubation difficult
- increased risk of infection
- change to coagulation increases susceptibility to pulmonary embolism
- need to deliver baby to ventilate the mother effectively
- 30 percent increase in oxygen consumption due to increase metabolic demand for oxygen by maternal body and fetoplacental unit
- lower reserves of oxygen and a greater susceptibility to hypoxia
- position of diaphragm rises as fetus grow, impeding ventilation
- increase transverse diameter of chest- this may make it more difficult to clear secretions
- mild respiratory alkalosis- facilitates fetal/maternal gradient gas exchange although subjective feelings of breathlessness are common
how does hormonal changes during pregnancy affect the respiratory tract
alter the vessels of the mucosal lining of the respiratory tract, leading to capillary engorgement and swelling of the lining of the nose, pharynx, larynx, and trachea= may experience nasal congestion and notice a change to the tone of their voice.
how can pregnancy affect ventilation for the woman
the pregnant woman at rest increases her ventilation by breathing more deeply rather than more frequently. this helps maintain normal oxygenation, but can contribute to a sense of breathlessness
what is the cause of the alterations in lung volume
largely to anatomical changes which allow greater lung expansion. the lower ribs flare, increasing the transverse diameter of the chest by 2 cm and the subcostal angle increases. changes begin before the enlarging uterus applies mechanical pressure. relaxation of the soft tissues of the rib cage is caused by increasing levels of the hormones, progesterone and relaxin, which contribute to increased rib cage elasticity.
what does the enhanced maternal ventilation result in
increased arterial oxygenation [PO2] and reduced arterial carbon dioxide. a benefit of lower maternal arterial carbon dioxide is that it facilitates fetal/maternal gas exchange at the placental bed
why might it be more difficult for pregnant women to clear secretions
as the pregnancy progresses the uterus displaces the diaphragm upward by about 5 cm decreasing functional residual capacity although the thoracic rib cage has splayed out to help compensate for this
what happens immediate postpartum
rapid reversal of changes with a reduction in progesterone and a decrease in intra-abdominal pressure. after delivery of the baby, blood gases return to pre-pregnant levels within 24 hours of delivery with anatomical and ventilator changes taking one to three weeks
what is tidal volume and how does it affect pregnancy
the amount of air passing in and out of the lungs during a single breath. increases by 40 percent in pg
what is inspiratory capacity and how does it affect pregnancy
the total amount of air that can be inspired with maximal effort. increases by late pg
what is functional residual capacity and how does it affect pregnancy
the volume of air in the lungs at the end of normal passive expiration. decreased by about 10-25 percent
what is vital capacity and how does it affect pregnancy
the maximum volume of air that can be moved out of the lungs during a single breath following maximal inspiration
what is respiratory rate and how does it affect pregnancy
12-15 breaths per minute at rest. no change/slight increase in pregnancy
what are some red flag presentations that would raise concern with breathlessness in pregnancy
- breathlessness of sudden onset
- breathlessness associated with chest pain
- orthopnea [difficulty breathing when laying flat] or paroxysmal nocturnal dyspnea [a sensation of SOB that wakes the woman up at night]
