Pulmonary Disorders in Pregnancy - WordPress.com · 2019. 11. 5. · Physiologic Pulmonary changes induced by pregnancy • Increasing metabolic demands cause a 30-percent rise in

Ina S. Irabon, MD, FPOGS, FPSRM, FPSGE

Obstetrics and GynecologyReproductive Endocrinology and Infertility

Laparoscopy and Hysteroscopy

Pulmonary Disorders in Pregnancy

Todownloadlecturedeck:

Reference• Williams Obstetrics 25th ed., 2018; Cunningham FG,

Leveno KJ, Bloom SL, Spong KY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS. Chapter 51

• Chapter 51

Outline1. Physiologic pulmonary changes induced by

pregnancy2. Pulmonary diseases in pregnancy:• ASTHMA • BACTERIAL PNEUMONIA• INFLUENZA PNEUMONIA• TUBERCULOSIS

àDiagnosis, treatment, effect of pregnancy, pregnancy outcome

• 1. Vital capacity and inspiratory capacity increase by approximately 20 percent by late pregnancy.

• 2. Expiratory reserve volume decreases from 1300 mL to approximately 1100 mL.

• 3. Tidal volume increases approximately 40 percent as a result of respiratory stimulation by progesterone.

• 4. Minute ventilation increases 30 to 40 percent due to increased tidal volume. As a result, arterial Po2 increases from 100 to 105 mm Hg.

PhysiologicPulmonarychangesinducedbypregnancy

Williams Obstetrics 24th ed., 2014; Cunningham FG, Leveno KJ, Bloom SL, Spong KY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS. Chapter 51

PhysiologicPulmonarychangesinducedbypregnancy• Increasing metabolic demands cause a 30-percent rise in

carbon dioxide (CO2) production. But, because of increased diffusion capacity and hyperventilation, the arterial PCO2 decreases from 40 to 32 mm Hg.

• 6. Residual volume decreases approximately 20 percent from 1500 mL to approximately 1200 mL.

• 7. Chest wall compliance is reduced by a third by the expanding uterus and increased abdominal pressure, which causes a 10-to 25-percent decrease in functional residual capacity—the sum of expiratory reserve and residual volumes.


1.ASTHMA

Asthma:Pathophysiology• Asthma is a chronic inflammatory airway syndrome with a

major hereditary component.

• Increased airway responsiveness and persistent subacute inflammation

• Asthma is heterogeneous, and there inevitably is an environmental allergic stimulant such as influenza or cigarette smoke in susceptible individuals


Asthma:Pathophysiology• The hallmarks of asthma: reversible airway obstruction from

bronchial smooth muscle contraction, vascular congestion, tenacious mucus, and mucosal edema.

• There is mucosal infiltration with eosinophils, mast cells, and T lymphocytes that causes airway inflammation and increased responsiveness to numerous stimuli

• inflammatory mediators include histamine, leukotrienes, prostaglandins, cytokines, and many others.

• Because F-series prostaglandins and ergonovine exacerbate asthma, these commonly used obstetrical drugs should be avoided if possible.


ClassificationofAsthmaseverity


FIGURE 51-1 Clinical stages of asthma. FEV1 = forced expiratory volume in 1second.

Although these changes are generally reversible and well tolerated by thehealthy nonpregnant individual, even early asthma stages may be dangerous for the

ClinicalstagesofASTHMA

FIGURE 51-1 Clinical stages of asthma. FEV1 = forced expiratory volume in 1second.

Although these changes are generally reversible and well tolerated by thehealthy nonpregnant individual, even early asthma stages may be dangerous for the

EffectofPregnancyonAsthma• Pregnancy has an unpredictable effect on underlying

asthma:• approximately 1/3 improves, 1/3 remains unchanged,

or 1/3 worsens • Exacerbations are more common with severe disease• Some women have asthma exacerbations during labor

and delivery.


Pregnancyoutcome• unless disease is severe, pregnancy outcomes are

generally excellent. • Increased morbidity appears to be significantly linked to

severe disease, poor control, or both • The incidence of spontaneous abortion in women with

asthma may be slightly increased• Fetal Effects: With reasonable asthma control, perinatal

outcomes are generally good.


Asthma:clinicalevaluation• useful clinical signs include labored breathing,

tachycardia, pulsus paradoxus, prolonged expiration, and use of accessory muscles.

• Signs of a potentially fatal attack include central cyanosis and altered consciousness.

• Arterial blood gas analysis provides objective assessment of maternal oxygenation, ventilation, and acid-base status. à results must be interpreted in relation to normal values for pregnancy.


Asthma:clinicalevaluation• Pulmonary function testing should be routine in the

management of chronic and acute asthma.

• Sequential measurement of the FEV1 or the peak expiratory flow rate—PEFR—are the best measures of severity.

• The PEFR correlates well with the FEV1, and it can be measured reliably with inexpensive portable meters.

• An FEV1 less than 1 L, or less than 20 % of predicted value, correlates with severe disease defined by hypoxia, poor response to therapy, and a high relapse rate.

• It is advisable for each woman to determine her own baseline when asymptomatic to compare with values when symptomatic.


ChronicAsthma:principlesofmanagement• 1. Patient education—general asthma management and its

effect on pregnancy

• 2. Environmental precipitating factors—avoidance or control. Viral infections—including the common cold—are frequent triggering events

• 3. Objective assessment of pulmonary function and fetalwellbeing—monitor with PEFR or FEV1

• 4. Pharmacological therapy—in appropriate combinations and doses to provide baseline control and treat exacerbations.


ChronicAsthma:management• In general, women with moderate to severe asthma

should measure and record either their FEV1 or PEFR twice daily.

• The FEV1 ideally is > 80 percent of predicted. For PEFR, predicted values range from 380 to 550 L/min.

• Therapeutic adjustments can be made using this


ChronicAsthma:management• Treatment depends on disease severity.


ChronicAsthma:management

• β-agonists help to relieve bronchospasm• Cor5costeroids treat the inflamma5on (an5-

inflammatory)• For mild asthma, inhaled b-agonists as needed are

usually sufficient. • For persistent asthma, inhaled cor0costeroids are

administered every 3 to 4 hours. • The goal is to reduce the use of β-agonists for

symptoma5c relief.


ChronicAsthma:management• Theophylline is a methylxanthine; bronchodilators and

possibly antiinflammatory agents.• used less frequently since inhaled corticosteroids became

available• useful for oral maintenance therapy if the initial response

to inhaled corticosteroids and β-agonists is not optimal

• Antileukotrienes inhibit leukotriene synthesis and include zileuton, zafirlukast, and montelukast àfor prevention, but they are not effective for acute disease.

For maintenance, they are used in conjunction with inhaledcorticosteroids to allow minimal dosing.


ChronicAsthma:management• Cromones include cromolyn and nedocromil, which

inhibit mast cell degranulation. • ineffective for acute asthma and are taken chronically for prevention. • not as effective as inhaled corticosteroids and are used primarily to treat

childhood asthma


ManagementofAcuteAsthma• Treatment of acute asthma during pregnancy is similar to that

for the nonpregnant asthmatic • Intravenous hydration may help clear pulmonary secretions,

and supplemental oxygen is given by mask. • The therapeutic aim is to maintain the PO2 > 60 mm Hg, and

preferably normal, along with 95-percent oxygen saturation. • First-line therapy for acute asthma includes a b-adrenergic

agonist (terbutaline, albuterol, isoetharine, epinephrine, isoproterenol, or metaproterenol, which is given subcutaneously, taken orally, or inhaled)• These drugs bind to specific cell-surface receptors and

activate adenylyl cyclase to increase intracellular cyclic AMP and modulate bronchial smooth muscle relaxation.


ManagementofAcuteAsthma• If not previously given for maintenance, inhaled corticosteroids

are commenced.• A nebulized anticholinergic drug may be added• for severe exacerbations, IV magnesium sulfate or theophylline

may prove effective• Corticosteroids should be given early to all patients with severe

acute asthma. • Unless there is a timely response to bronchodilator + inhaled

corticosteroid therapy, then oral or parenteral corticosteroids are given:• oral prednisone or prednisolone or IV methylprednisolone in a

dose of 30 to 45 mg daily for 5 to 10 days without tapering • Because their onset of action is several hours, corticosteroids

are given initially along with b-agonists for acute asthma.


StatusAsthmaticus• Severe asthma of any type not responding after 30 to 60

minutes of intensive therapy

• Consideration should be given to early intubation when maternal respiratory status worsens despite aggressive treatment

• Fatigue, carbon dioxide retention, and hypoxemia are indications for mechanical ventilation.


Labor andDelivery• For the laboring asthmatic, maintenance medications are

continued through delivery.

• Stress-dose corticosteroids are administered to any woman given systemic corticosteroid therapy within the preceding 4 weeks.

• The usual dose is 100 mg of hydrocortisone given intravenously every 8 hours during labor and for 24 hours after delivery.


Labor andDelivery

• Epidural analgesia is ideal.

• For surgical delivery, conduction analgesia is preferred because tracheal intubation can trigger severe bronchospasm.

• Prostaglandin F2a (eg carbpprost) or ergotamine derivatives (eg methergine) are contraindicated because they may cause significant bronchospasm.


2.BACTERIALPNEUMONIA

BacterialPneumonia• Any pregnant woman suspected of having pneumonia should

undergo chest radiography.

• Typical symptoms include cough, dyspnea, sputum production, and pleuritic chest pain.

• Mild upper respiratory symptoms and malaise usually precede these symptoms, and mild leukocytosis is usually present.


Riskfactorstothatshouldprompthospitalization:


BacterialPneumonia• With severe disease, admission to an ICU or

intermediate care unit is advisable. • Severe pneumonia is a common cause of acute

respiratory distress syndrome during pregnancy• Antimicrobial treatment is empirical :

• Because most adult pneumonias are caused by pneumococci, mycoplasma, or chlamydophila, monotherapy initially is with a macrolide—azithromycin, clarithromycin, or erythromycin.


BacterialPneumonia

Hypothermia—core temperature <36°CHypotension requiring aggressive fluid resuscitationaCriteria of the Infectious Diseases Society of America/American ThoracicSociety.PaO2/FiO2 = partial pressure oxygen in arterial blood/fraction of inspired oxygen; WBC = white blood cell.Adapted from Mandell, 2007.

With severe disease, admission to an intensive or intermediate care unit isadvisable. Approximately 20 percent of pregnant women admitted to ParklandHospital for pneumonia require this level of care (Zeeman, 2003). Severepneumonia is a relatively common cause of acute respiratory distress syndrome(ARDS) during pregnancy, and mechanical ventilation may become necessary(Chap. 47, p. 919). Indeed, of the 51 gravidas who required mechanical ventilationin the review by Jenkins and coworkers (2003), 12 percent had pneumonia.

Initial antimicrobial and antiviral treatment is empirical (Mandell, 2015).Because most adult bacterial pneumonias are caused by pneumococci,mycoplasma, or chlamydophila, monotherapy initially is with a macrolide—azithromycin, clarithromycin, or erythromycin (Table 51-4). Yost and colleagues(2000) reported that erythromycin monotherapy, given IV and then orally, waseffective in all but one of 99 pregnant women with uncomplicated pneumonia.During influenza season, we routinely administer oseltamivir treatment along withempirical therapy for bacterial pneumonia.

TABLE 51-4. Empirical Antimicrobial Treatment for Community-AcquiredPneumonia

Uncomplicated, otherwise healthya

Macrolidesb: clarithromycin or azithromycinPLUSOseltamivir for suspected influenza A infectionSevere pneumoniac

Respiratory fluoroquinolones: moxifloxacin, gemifloxacin, or levofloxacinorβ-lactams: amoxicillin/clavulanate, ceftriaxone, cefotaxime, or cefuroxime plus a

macrolidePLUSOseltamivir for suspected influenza A infectionaUse as inpatient or outpatient regimen.bDoxycycline may be given instead if postpartum.

BacterialPneumonia• For women with severe pneumonia:• (1) a respiratory fluoroquinolone— levofloxacin,

moxifloxacin, or gemifloxacin;• (2) a macrolide plus a β-lactam—high-dose amoxicillin or

amoxicillin-clavulanate, which are preferred β-lactams.

• β-lactam alternatives include ceftriaxone, cefpodoxime, or cefuroxime (preferred for “high-level” resistance of pneumococcal isolates to macrolides)

• For community-acquired methicillin-resistant S aureus(MRSA) is suspected: Vancomycin or linezolid are added


BacterialPneumonia• Clinical improvement is usually evident in 48 to 72 hours

with resolution of fever in 2 to 4 days. Radiographic abnormalities may take up to 6 weeks to completely resolve

• Pneumonia treatment is recommended for a minimum of 5-7 days


PregnancyoutcomewithPneumonia• Prematurely ruptured membranes and preterm delivery

are frequent complications

• twofold increase in low-birthweight infants

• increased incidences of preterm and growth-restricted infants as well as preeclampsia and cesarean delivery


Pneumococcalvaccine• Two pneumococcal vaccines: 23-serotype older preparation

and a newer 13- serotype vaccine:

• The 23-serotype vaccine is 60- to 70-percent protective, and its use lowers emergence of drug-resistant pneumococci

• The 13-serotype vaccine is not recommended for otherwise healthy pregnant women à recommended for women who are immunocompromised, including those with HIV infection; significant smoking history; diabetes; cardiac, pulmonary, or renal disease; and asplenia, such as with sickle-cell disease


3.INFLUENZAPNEUMONIA

InfluenzaPneumonia• Influenza A and B are RNA viruses that cause respiratory

infec9on, including pneumoni9s

• virus is spread by aerosolized droplets and quickly infects

ciliated columnar epithelium, alveolar cells, mucus gland cells,

and macrophages.

• Disease onset is 1 to 4 days following exposure.

• Common symptoms include fever, cough, myalgia, and chills

• In most healthy adults, infec9on is self-limited.

TreatmentofInfluenza• Supportive treatment is recommended for uncomplicated influenza• Early antiviral treatment is effective • Hospitalization is considered for severely ill women• The CDC (2016b) recommends neuraminidase inhibitors given within 2

days of symptom onset for chemoprophylaxis and treatment of influenza A and B:• The drugs interfere with release of progeny virus from infected host cells and

thus prevent infection of new host cells • Oseltamivir is given orally, 75 mg twice daily, or zanamivir is given by

inhalation, 10 mg twice daily. • Recommended treatment duration with either is 5 days. • The drugs shorten the course of illness by 1 to 2 days, and they probably

reduce the risk for pneumonitis • the drugs are not teratogenic in animal studies and are considered low risk

• Vaccination for influenza A is recommended by the American College of Obstetricians and Gynecologists (2016b) and the CDC (2016b).

4.TUBERCULOSIS

Tuberculosis• Infection is via inhalation of Mycobacterium tuberculosis,

which incites a granulomatous pulmonary reaction.

• Manifestations usually include cough with minimal sputum production, low-grade fever, hemoptysis, and weight loss.

• Various infiltrative patterns are seen on chest radiograph, and there may be associated cavitation or mediastinallymphadenopathy.

• Acid-fast bacilli are seen on stained smears of sputumWilliams Obstetrics 24th ed., 2014; Cunningham FG, Leveno KJ, Bloom SL, Spong KY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS. Chapter 51

Tuberculosis:Diagnosis• There are two types of tests to detect latent or ac2ve

tuberculosis:

1. tuberculin skin test (TST) – PPD 5 tuberculin unitsA posi2ve skin test result measures ≥5 mm in diameter and requires evalua2on for ac2ve disease, including a chest radiograph.

2. interferon-gamma release assays (IGRAs) - blood tests that measure interferon-gamma release in response to

an2gens present in M tuberculosis, but not bacille CalmeCe-Guérin(BCG) vaccine

- Quan2FERON-TB Gold and T-SPOT.TB tests Williams Obstetrics 24th ed., 2014; Cunningham FG, Leveno KJ, Bloom SL, Spong KY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS. Chapter 51

Tuberculosis:Treatment• Recommended initial treatment for active

tuberculosis in pregnant patients is a four-drug regimen: isoniazid, rifampin, ethambutol, and pyrazinamide, along with pyridoxine.

• bactericidal phase = In the first 2-month phase, all four drugs are given

• continuation phase = 4-month phase of isoniazid and rifampin


Tuberculosis:Treatment• Breast feeding is not prohibited during

antituberculous therapy.

• Of the second-line regimens, the aminoglycosides— streptomycin, kanamycin, amikacin, and capreomycin—are ototoxic to the fetus and are contraindicated

• Latent infection: 9 months tx with isoniazid only


Neonataltuberculosis• Tubercular bacillemia can infect the placenta, but it is

uncommon that the fetus becomes infected (congenital tuberculosis)

• also applies to newborns who are infected by aspiration of infected secretions at delivery.

• Neonatal infection is unlikely if the mother with active disease has been treated before delivery or if her sputum culture is negative.

• If untreated, the risk of disease in the infant born to a woman with active infection is 50 percent in the first year

• Neonatal tuberculosis simulates other congenital infections and manifests with hepatosplenomegaly, respiratory distress, fever, and lymphadenopathy


Summary1. Physiologic pulmonary changes induced by

pregnancyincrease or decrease?

vital capacityexpiratory reserve volumetidal volumeminute ventilationresidual volume

Outline

1. Pulmonary diseases in pregnancy:• ASTHMA • BACTERIAL PNEUMONIA• IINFLUENZA PNEUMONIA• TUBERCULOSIS

àDiagnosis, treatment, effect of pregnancy, pregnancy outcome

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Pulmonary Disorders in Pregnancy - WordPress.com · 2019. 11. 5. · Physiologic Pulmonary changes induced by pregnancy • Increasing metabolic demands cause a 30-percent rise in

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