Respiratory Failure and ARDS MCQs

Pulmonary surfactant increases lung compliance by lowering alveolar surface tension. As a result, the pressure gradient needed to inflate the alveoli decreases, as does the work of breathing. Reference: Ganong, pp 654-6558. Kasper et al., pp 1583, 1592-1595. Levitzky, pp 26-28. Stead et al., p 270.

When air enters the pleural space due to interruption of the pleural surface through either the rupture of the lung or a hole in the chest wall, the pressure in the pleural space becomes atmospheric, the lung on the affected side collapses because of the lung's tendency to recoil inward, and the chest wall on the affected side recoils outward. Because the intrapleural pressure is atmospheric, the mediastinum shifts farther to the normal side with each inspiration. With collapse of the lung, the V / Q ratio on the affected side decreases. Reference: Ganong, p 688. Kasper et al., p 1568. Levitzky, pp 12, 116-Stead et al., pp 273-274.

Profound hypoxia depresses the central nervous system, including the medullary respiratory centers. As a result, alveolar ventilation may decrease, resulting in an increased PaCO2. A decrease in metabolic activity would decrease the rate of production of carbon dioxide (VCO2), which would decrease PaCO2, assuming that alveolar ventilation does not change. If an alveolar capillary block is severe, retention of CO2 could briefly occur, but the coexistent hypoxemia would cause reflex hyperventilation with a decrease in PaCO2. At a constant tidal volume and respiratory rate, a decrease in the deadspace volume would increase alveolar ventilation, and thus lower the PaCO2. Reference: Kasper et al. pp 209-210, 1624-1637. Levitzky, pp 66, 73-74, 136-138.

If metabolic acidosis persists after successful defibrillation and with adequate ventilation, 1 mEq/kg sodium bcarbonate may be given. Bicarbonate therapy can increase extracellular pH only if the CO2 produced can be removed by adequate ventilation . Indeed if hypercapnia occurs then as CO2 crosses cell membranes easily, intracellular pH may decrease even further with further deterioration of cellular function. Sodium bicarbonate has - Negative inotropic effect Reduces cerebral blood flow Shifts oxygen dissociation curve to the left inhibiting oxygen release to tissues Reference: Harrison's Principles of Internal Principles, 20 th edition, ch:299 pg:2063

Ans. is 'd' i.e., Rhomboid major Triangle of auscultation has the following boundaries Superiorly and medially, by the inferior portion of the Trapezius. Inferiorly, by the Latissimus Dorsi. Laterally, by the medial border of the scapula. The superficial floor of the triangle is formed by the Serratus anterior and the lateral portion of the erector spinae muscles. Deep to these muscles are the osseous portions of the 6" and 7th ribs and the internal and external intercostal muscles. Typically, the Triangle of Auscultation is covered by the Scapula. To better expose the triangle and listen to respiratory sounds with a stethoscope, patients are asked to fold their arms across their chest, medially rotating the scapulae, while bending forward at the trunk, somewhat resembling a fetal position.

Answer- D. Tension Pneumothorax Emergency thoracotomy is indicated after chest trauma in following conditions : Cardiac arrest (resuscitative thoractomy) Massive hemoththorax (>1500 mL of blood through the chest tube acutely or > 200-300 ml/hr after initial drainage. Penetrating injuries of the anterior aspect of the chest with cardiac tamponade. Large open wounds of the thoracic cage. Major thoracic vascular injuries in the presence of hemodynamic instability

Sildenafil is a phosphodiesterase-5 inhibitor used in management of erectile dysfunction. Like nitrates it also increases the release of NO resulting in hypotension. There is a significant risk of hypotension when sildenafil is used with nitrates . There should be at least 24 hours gap between administration of nitrates and short acting PDE5 inhibitors like sildenafil and 48 hours between the use of long acting Tadalafil. Reference: Harrison's Principles of Internal Medicine 21 st edition Page no: 2050

Hypospadias, micropenis and cryptorchidism point towards reduced androgen exposure in utero Kallmann syndrome is characterised by hypogonadotropic hypogonadism with anosmia. Although hypogonadotropic hypogonadism can be caused by pituitary disorders, a common presentation in childhood is with anosmia (Kallman's syndrome). Causes of hypogonadotropic hypogonadism:. Genetic : Mutations in following genes: KAL1 FGFR1 GNRHR PC1 Acquired: (more common) Stress Athletes Chronic illness Obesity Hyperprolactinemia Sellar lesions Reference : Harrison's Principles of Internal Medicine 21 st edition Page 3014