Queensland Lung Cancer Screening Study: rationale, design and methods.

BACKGROUND: Lung cancer is the leading cause of cancer-related mortality in Australia. Screening using low-dose computed tomography (LDCT) can reduce lung cancer mortality. The feasibility of screening in Australia is unknown. This paper describes the rationale, design and methods of the Queensland Lung Cancer Screening Study. AIMS: The aim of the study is to describe the methodology for a feasibility study of lung cancer screening by LDCT in Australia. METHODS: The Queensland Lung Cancer Screening Study is an ongoing, prospective observational study of screening by LDCT at a single tertiary institution. Healthy volunteers at high risk of lung cancer (age 60-74 years; smoking history ≥30 pack years, current or quit within 15 years; forced expiratory volume in 1s ≥50% predicted) are recruited from the general public through newspaper advertisement and press release. Participants receive a LDCT scan of the chest at baseline, year 1 and year 2 using a multidetector helical computed tomography scanner and are followed up for a total of 5 years. Feasibility of screening will be assessed by cancer detection rates, lung nodule prevalence, optimal management strategies for lung nodules, economic costs, healthcare utilisation and participant quality of life. CONCLUSIONS: Studying LDCT screening in the Australian setting will help us understand how differences in populations, background diseases and healthcare structures modulate screening effectiveness. This information, together with results from overseas randomised studies, will inform and facilitate local policymaking.

Utility of clinical parameters of tissue oxygenation in a quantitative model of irreversible hemorrhagic shock.

The aim of this study was to assess the value of parameters of tissue oxygenation in monitoring the progression to irreversibility in a quantitative model of hemorrhagic shock. Rats were bled to a mean arterial pressure of 40 mmHg and were maintained at this level by further blood withdrawal until the compensation endpoint; this point was defined as the time at which the rat was no longer able to maintain its blood pressure at this level and shed blood was required for transfusion. The shock period was maintained until 0%, 20%, 40%, or 50% of the maximum shed blood volume (MBV) had been returned (n = 10 in each group, total n = 40). The animals were then resuscitated with remaining shed blood plus twice MBV as lactated Ringer's solution to MAP > 80 mmHg. Blood gas and serum lactate samples were measured at baseline, compensation endpoint, and at the time of resuscitation, and 24 h survival was recorded. Increasing the severity of shock progressively worsened the acidosis, with increased base deficit and lacticacidemia, and deterioration in central venous oxygen saturation (CvO2). Tissue oxygenation parameters, particularly CvO2, predicted subsequent mortality. Lactate levels only predicted irreversibility in late, severe shock. This quantitative model of hemorrhagic shock showed that tissue oxygenation parameters can be used to monitor the progression from the decompensated phase of hemorrhagic shock to irreversibility. Furthermore, this experimental study suggests that venous indices may be a valuable tool in reflecting the severity of hemorrhagic insult in a setting when arterial blood samples may not be easily available.