Volume. 35, No. 2 july. 2011 - The Chest and Heart Association of ...

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Chest & Heart Journal Vol. 35, No.-2, July 2011Asthma is a chronic inflammatory disorder causinghyper-responsiveness of theairways to certain stimuli resulting in recurrentvariable airflow limitation , at least partlyreversible ,presenting as wheezing , breathlessness,chest tightness ,and coughing 1 .Asthma is aserious health problem worldwide• Its prevalence has increased in the past twodecades• Approximately 8% of pregnant women reportedcurrent asthma• It is the most common chronic condition inpregnancyChanges in Respiratory Functions duringPregnancyNormal pregnancy is associated with –• 20% increase in oxygen consumption• 15% increase in the maternal metabolic rate• Achieved via a 40-50% increase in restingminute ventilation ,resulting mainly from a risein tidal volume rather than respiratory rate• This hyperventilation causes –- Pao 2to increase-Paco 2to fall ,with a compensatory fall in serumbicarbonate to 18-22 mmol/l- A mild respiratory alkalosis is therefore normalin pregnancy (arterial pH 7.44 )• 75% of women experience a subjective feelingof breathlessness during pregnancy• In late pregnancy the diaphragmatic elevationcaused by the enlarging uterus leads to adecrease in FRC.• No change in PEFR or FEV 1in pregnancy• Decrease FRC may exacerbate hypoxaemiabecause of premature airway closure whenacute asthma complicates pregnancy. 2Physiological factors affecting asthma inpregnancy• Increase in free cortisol levels may protectagainst inflammatory triggers• Increase in progesterone may improve airwayresponsiveness• Increase in prostaglandin F2á may promoteairway constriction• Placental 11â hydrxysteroid dehydrogenasetype 2 decreased activity is associated with anincrease in placental cortisol concentration andlow birth weight• Placental gene expression of inflammatorycytokines may promote low birth weight• Modification of cell mediated immunity mayinfluence maternal response to infection andinflammation. 3Effects of Pregnancy on Asthma• The course of asthma in pregnancy in anindividual woman is largely unpredictable• Women with mild disease are unlikely toexperience problems , whereas those withsevere asthma are at greater risk ofdeterioration ,particularly late in pregnancy• Asthma may improve during pregnancy due toprogesterone mediated brochodilation andincreased serum cortisol levels• Asthma may deteriorate during pregnancy dueto increased stress and increased gasrooesophagealreflux• Many asthmatic patients experience worseningof symptoms during pregnancy because theystop or reduce medication due to fears aboutits safety.• In most women asthma has no effect upon theoutcome of pregnancy• Severe ,poorly controlled asthma may have anadverse effect on fetal outcome as a result ofchronic or intermittent maternal hypoxaemia• Increase risk of premature labour• Low birth weight• Higher rates of pregnancy induced-hypertension-Pre-eclamsia and-Caesarean section• Increased incidence of tachypnoea of thenewborn108
Asthma in Pregnancy – An overview• Neonatal hypoglycemia• Neonatal siezures• Admission to the neonatal intensive care unitsin the babies of asthmatic women 4Special considerations in pregnant women withasthma• Ensure optimal asthma control throughoutpregnancy• Manage asthma exacerbations aggressively• Avoid delay in diagnosis and treatment• Assess medication needs and response totherapy frequently• Ensure adequate patient education andacquisition of self management skills• Treat rhinitis ,gastric reflux and othercomorbidities adequately• Encourage smoking cessation• Assess pulmonary function with spirometry atleast monthly• Offer a multidisciplinary team approach 3• Be aware of the risk of pre-elampsia andintrauterine growth retardation 5Md.Abdul Qayyum et al.Main differential diagnosis in pregnantwomen with dyspnoea• Asthma• Physiological dyspnoea of pregnancy• Pulmonary embolism• Pulmonary oedema• Peripartum cardiomyopathy• Amniotic fluid embolismManagement of AsthmaAll patients should be educated regarding therelationship between asthma and pregnancyShould be taught about-self-treatment-Inhaler techniques-Adherence to medicationControl of potential environmental triggers 6Appropriate management of commoncoexisting conditions such as-Rhinitis-Sinusitis-Gastro-esophageal refuxWomen who smoke must be informed of thepotential adverse effects of smoking on the fetusShould be strongly encouraged to quitAssessment of Asthma control in pregnant womenVariable Well-controlled Asthma not well Very poorlyAsthma controlled controlled AsthmaFrequency of symptoms 2days/wk Throughout the dayFrequency of night time 4 times/wkawakeningInterference with normal None Some ExtremeactivityUse of short-acting â- 2 days/wk Several times/dayagonist for symptomcontrolFEV 1or PEFR(% of the >80 60-80 2 in past 12 monthsuse of systemicmonthcorticosteroid(no.)109
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Volume. 35, No. 2 july. 2011 - The Chest and Heart Association of ...

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