Pro/con debate: should PaCO2 be tightly controlled in all patients with acute brain injuries?

You are the attending intensivist in a neurointensive care unit caring for a woman five days post-rupture of a cerebral aneurysm (World Federation of Neurological Surgeons Grade 4 and Fisher Grade 3). She is intubated for airway protection and mild hypoxemia related to an aspiration event at the time of aneurysm rupture, but is breathing spontaneously on the ventilator. Your patient is spontaneously hyperventilating with high tidal volumes despite minimal support and has developed significant hypocapnia. She has not yet developed the acute respiratory distress syndrome. You debate whether to tightly control her partial pressure of arterial carbon dioxide, weighing the known risks of acute hypocapnia in other forms of brain injury against the potential loss of clinical neuromonitoring associated with deep sedation and neuromuscular blockade in this patient who is at high risk of delayed ischemia from vasospasm. You are also aware of the potential implications of tidal volume control if this patient were to develop the acute respiratory distress syndrome and the effect of permissive hypercapnia on her intracranial pressure. In this paper we provide a detailed and balanced examination of the issues pertaining to this clinical scenario, including suggestions for clinical management of ventilation, sedation and neuromonitoring. Until more definitive clinical trial evidence is available to guide practice, clinicians are forced to carefully weigh the potential benefits of tight carbon dioxide control against the potential risks in each individual patient based on the clinical issues at hand.

The attitude of Canadian university students toward a behavior-based blood donor health assessment questionnaire.

BACKGROUND: In Canada, all men who have sex with men (MSM) are indefinitely deferred from donating blood. The purpose of this study was to determine the acceptability of an alternative behavior-based donor health questionnaire among Canadian university students. Further we sought to determine the perception of blood safety associated with specific risk behaviors. STUDY DESIGN AND METHODS: Questions found on the Canadian Blood Services' donor health assessment questionnaire as well as from studies assessing high-risk behavior for human immunodeficiency virus infection were included. For each question participants were asked to rate the acceptability, comfort in answering, perceived effect on blood safety, and whether the question would deter them from donating blood. Data were analyzed using nonparametric tests. RESULTS: A total of 741 students participated in the study. Questions regarding sexual practices of the donor were rated less important for blood safety compared to those assessing for sexually transmitted infections, sex for money, and injection drug use (30%-62% vs. 69%-95% unsafe). A total of 24.4% of students rated both questions on MSM status and a behavior-based alternative as equally unacceptable. We found an inverse correlation between perception of safety and acceptability of questions. CONCLUSION: Our findings suggest that a behavior-based screening modification is unlikely to change opinions or satisfy those who object to the MSM current policy in place. Acceptability of these questions might be related to a poor understanding of the effect of sexual practices on blood supply safety.