Prolonged Unexplained Hypoxemia as Initial Presentation of Cirrhosis: A Case Report

In vivo photoacoustic assessment of the oxygen saturation changes in the human radial artery: a preliminary study associated with age

SIGNIFICANCE

We demonstrate the potential of probing the sO2 change under blood flow in vivo using photoacoustic (PA) imaging and sheds light on the complex relationship between RBC aggregation and oxygen delivery.

AIM

To conduct in vivo assessments of the sO2 in the radial artery of healthy volunteers and simultaneously probe the relation between the sO2 and hemodynamic behavior such as red blood cell (RBC) aggregation.

APPROACH

The effects of PA-based measurements of blood hemodynamics were studied as a function of the subjects' age (20s, 30s, and 40s). The pulsatile blood flow in the human radial artery of 12 healthy subjects was imaged in the 700 to 900 nm optical wavelength range using a linear array-based PA system.

RESULTS

The PA power when blood velocity is minimum (Pamax) was larger than the one attained at maximum blood velocity (Pamin), consistent with predictions based on the cyclical variation of RBC aggregation during pulsatile flow. The difference between Pamin and Pamax at 800 nm (ΔPa800) increased with age (1.7, 2.2, and 2.6 dB for age group of 20s, 30s, and 40s, respectively). The sO2 computed from Pamax was larger than the one from Pamin.

CONCLUSIONS

The ΔPa800 increased with participant age. The ΔPa800 metric could be a surrogate of noninvasively monitoring the age-induced changes in RBC aggregation. The sO2 change during a cycle of pulsatile blood flow also increased with age, demonstrating that RBC aggregation can affect the sO2 change.

An Unusual Case of Refractory Hypoxia on the ICU

We present the case of a 68-year-old gentleman who presented with breathlessness and was found to have NSTEMI, pulmonary oedema, and hypoxia. He remained hypoxic despite appropriate treatment and was found to have preserved LV function and raised cardiac output. CT pulmonary angiogram was negative but a cirrhotic liver was incidentally noted and later confirmed via ultrasound. Bedside examination was positive for orthodeoxia, suggesting a diagnosis of hepatopulmonary syndrome (HPS). The finding of significant intrapulmonary shunting on “bubble” echocardiography confirmed the diagnosis. This patient did not have previously diagnosed liver disease and had largely normal LFTs when the diagnosis was first suspected. We discuss HPS in the context of ICU and suggest how it may be screened for using simple tests. There is no correlation between the presence of HPS and severity of liver disease, yet we believe this is the first reported adult case of HPS on the ICU without previously diagnosed cirrhosis.

Persistent Unexplained Dyspnea: A Case of Hepatopulmonary Syndrome

Regarding a patient with dyspnea, the history and physical examination often lead to the correct diagnosis. In some circumstances, when more than one underlying disease is present, the diagnostic process can be more challenging. We describe an unusual case of dyspnea and persistent hypoxemia related to a hepatopulmonary syndrome in a 53-year-old patient with known heart failure and chronic liver disease. Initially managed with intravenous diuretic therapy, due to signs of lung and peripheral congestion, our patient did not improve as expected; therefore we performed more advanced studies with a chest-abdomen CT scan and a right heart catheterization. They showed, respectively, no signs of parenchymal and vasculature lung disease, a cirrhotic liver disease, splenomegaly, signs of portal hypertension, and high cardiac output with normal pulmonary vascular resistance. These results, along with the association of hypoxemia and chronic liver disease, suggested a hepatopulmonary syndrome. The diagnosis was confirmed by the demonstration of an intrapulmonary vascular dilatation with right to left shunt during a microbubble transthoracic echocardiography and a lung perfusion scan. Liver transplantation is the only successful treatment for this syndrome; however, the patient became soon unsuitable for this strategy, due to a rapid clinical deterioration.