Tuesday, 12 January 2010

ARDS in pregnancy

What is ARDS?

It is form of acute respiratory failure
characterized by (i) alveolar hypoxemia (ii) increased capillary permeability
resulting from diffuse & ongoing pulmonary inflammation.


Current definition
(i)acute onset
(ii) a PaO2/FIO2 ratio, or hypoxia score,of <=200, regardless of positive end expiratory pressure (iii) bilateral infiltrates on chest radio graph (iv) a pulmonary artery occlusion pressure of <=18 mm Hg or the absence of clinical evidence of left atrial hypertension. 4phases
(i)exudative phase-increased capillary permeability resulting in alveoli filled with fluid.(0-4days)
(ii)proliferative phase(4-8days)
(iii)fibrotic phase(>8 days)
(iv)recovery


2 type of causes

(i) Direct-(pulmonary causes)direct lung injury Example: Aspiration
(ii)Indirect(extrapulmonary causes) Ex:Acute pancreatitis in pregnancy

3 categories in pregnancy
(A)Pathogeneses Minimally Affected by Pregnancy (i)Sepsis with prolonged hypotension
(B)Pathogeneses Affected by pregnancy (i)aspiration (ii)acute pyelonephritis
(C)Pathogeneses unique to pregnancy (i)preeclampsia

Differential diagnosis

(i)Cardiogenic pulmonary odema
(ii)volume overload

Management
Multidisciplinary management involving Obstetrician, Intensivists, Anaesthetists and Neonatologist.

3 aspects of management
(i)initial stabilization
(ii)confirming the diagnosis & identifying the aeitiology
(iii)assessing fetal well being & making the delivery plan


Treatment principles
(A) treat primary problem
(B)physiological support(lungs & other organs)
(C) avoid complications

Different methods of ventilatory support
(i)Noninvasive Positive-Pressure Ventilation-There is limitation in pregnancy due to raised risk of air way compromise & aspiration.
(ii)Lung-Protective Conventional Ventilation-(endotracheal intubation)

Advanced options :
(a)airway pressure-release ventilation (APRV)
(b)high-frequency oscillatory ventilation(HFOV)
(c)lung recruitment maneuvers(LRMs)
(d) prone positioning
(e) inhaled nitric oxide

Timing & mode of delivery
The available evidence is limited,so timing & mode of delivery should be as per standard obstetric practice.

PowerPoint presentations on ARDS (I) (II)
Excellent PowerPoint on Critical care in pregnancy






References
(1)Acute respiratory distress syndrome in pregnancy;Daniel E. Cole, MD; Tara L. Taylor, MD; Deirdre M. McCullough, MD; Catherine T. Shoff, DO;Stephen Derdak, DO (Crit Care Med 2005; 33[Suppl.]:S269 –S278)

(2)Acute Respiratory Distress Syndrome inPregnancy and the Puerperium: Causes,Courses, and Outcomes
VAL CATANZARITE, MD, PhD, DAVID WILLMS, MD, DAVIES WONG, MD,
CHARLES LANDERS, MD, LARRY COUSINS, MD, AND DAVID SCHRIMMER, MD
.
Obstetrics & Gynecology:May 2001 - Volume 97 - Issue 5 - p 760-764