All of the following are good prognostic findings in Hodgkin's disease, except:

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Atmospheric air contains approximately 21% oxygen (O2) and 0.04% carbon dioxide (CO2), meaning O2's percentage is much higher than CO2's, reflecting their natural abundances. Solubility in blood, governed by Henry's law, depends on the solubility coefficient of each gas. O2 has a solubility coefficient of about 0.024 ml O2/mmHg/L blood, while CO2's is much higher at 0.51 ml CO2/mmHg/L blood over 20 times greater. This means CO2 is far more soluble in solution than O2, despite its lower atmospheric presence. In blood, O2 relies heavily on hemoglobin binding (98% of transport), with only ~1-2% dissolved, whereas CO2 is transported dissolved (~7%), as bicarbonate (~70%), and bound to hemoglobin (~23%), leveraging its high solubility. Thus, O2's higher atmospheric percentage contrasts with its lower solubility compared to CO2, driving distinct transport mechanisms critical for respiration and acid-base balance.

Correct Answer: B

Rationale: Surfactant, a phospholipid-protein mix from type II alveolar cells, lines alveoli and reduces surface tension of the fluid layer, preventing collapse and easing lung expansion. Normally, water's high surface tension (~72 dynes/cm) pulls alveolar walls inward, but surfactant lowers it (to ~5-10 dynes/cm), stabilizing smaller alveoli per Laplace's law (P = 2T/r). It doesn't increase pleural pressure, which remains negative (~-4 mmHg at rest) to keep lungs expanded surfactant affects intra-alveolar dynamics, not pleural space. It doesn't directly decrease alveolar pressure (typically atmospheric at rest, ~760 mmHg); that's a muscle-driven effect. It makes inspiration easier, not harder, by reducing the work needed to overcome tension, countering collapse tendencies. Pneumothorax relates to pleural breach, not surfactant. Reducing surface tension is the true function, critical for neonatal lung maturation and preventing atelectasis, distinguishing it from pressure or effort-related misconceptions.

Correct Answer: A

Rationale: Work of breathing (WOB) is the energy required to overcome elastic (compliance) and resistive (airway) forces during ventilation. Lung compliance (C = ΔV / ΔP) measures lung stretchability; low compliance (stiff lungs) increases pressure needed for a given volume, raising WOB. Thus, WOB is inversely related to compliance when C decreases, WOB increases, as in fibrosis. During exercise, WOB rises with higher ventilation rates and volumes, not remaining constant. Airway resistance (R) directly affects WOB; higher R (e.g., asthma) increases effort, contradicting not affected.' In pulmonary fibrosis, stiff lungs (low compliance) elevate WOB, not reduce it, unlike emphysema where high compliance might lower elastic work but raise resistive work. The inverse compliance relationship is fundamental, as WOB = ∫P dV, where pressure (P) rises as compliance falls, making this the correct statement reflecting respiratory mechanics.

Correct Answer: A

Rationale: Functional residual capacity (FRC) is the volume in the lungs after a normal expiration, equaling expiratory reserve volume (ERV) plus residual volume (RV). The spirogram shows maximal inhalation to total lung capacity (TLC) and exhalation to RV, with VC (vital capacity) as TLC - RV. RV is given as 1.0 L via helium dilution. FRC = ERV + RV, but without the figure, assume a typical female FRC (~2-3 L). If VC is ~4 L (normal for a young woman) and TLC ~5 L, then after maximal exhalation to RV (1 L), the difference from TLC to FRC includes ERV. Standard ERV is ~1-1.5 L; with RV = 1 L, FRC = 1 + 1 = 2.0 L fits option A, plausible for a smaller female frame. Higher values (2.5-3.5 L) align with larger individuals or males (~3 L). Without exact spirogram data, 2.0 L is reasonable, matching RV + minimal ERV, consistent with helium-derived RV and typical physiology.