• Comparison of arterial and venous blood gases and the effects of analysis delay and air contamination on arterial samples in patients with chronic obstructive pulmonary disease and healthy controls.

      O'Connor, T M; Barry, P J; Jahangir, A; Finn, C; Buckley, B M; El-Gammal, A; Department of Respiratory Medicine, Mercy University Hospital, Cork, Ireland., terryoconnor@eircom.net (2012-01-31)
      BACKGROUND: Arterial blood gases (ABGs) are often sampled incorrectly, leading to a 'mixed' or venous sample. Delays in analysis and air contamination are common. OBJECTIVES: We measured the effects of these errors in patients with chronic obstructive pulmonary disease (COPD) exacerbations and controls. METHODS: Arterial and venous samples were analyzed from 30 patients with COPD exacerbation and 30 controls. Venous samples were analysed immediately and arterial samples separated into non-air-contaminated and air-contaminated specimens and analysed at 0, 30, 60, 90 and 180 min. RESULTS: Mean venous pH was 7.371 and arterial pH was 7.407 (p < 0.0001). There was a correlation between venous and arterial pH (r = 0.5347, p < 0.0001). The regression equation to predict arterial pH was: arterial pH = 4.2289 + 0.43113 . venous pH. There were no clinically significant differences in arterial PO associated with analysis delay. A statistically significant decline in pH was detected at 30 min in patients with COPD exacerbation (p = 0.0042) and 90 min in controls (p < 0.0001). A clinically significant decline in pH emerged at 73 min in patients with COPD exacerbation and 87 min in controls. Air contamination was associated with a clinically significant increase in PO in all samples, including those that were immediately analyzed. CONCLUSIONS: Arterial and venous pH differ significantly. Venous pH cannot accurately replace arterial pH. Temporal delays in ABG analysis result in a significant decline in measured pH. ABGs should be analysed within 30 min. Air contamination leads to an immediate increase in measured PO, indicating that air-contaminated ABGs should be discarded.
    • Multiple sclerosis exceptionally presenting as parkinsonism responds to intravenous methylprednisolone.

      Saidha, S; Mok, T H; Butler, M; Fanning, N; Harrington, H; Department of Neurology, Mercy University Hospital, Grenville Place, Cork,, Ireland. shivsaidha@physicians.ie <shivsaidha@physicians.ie> (2012-01-31)
      Parkinsonism due to multiple sclerosis (MS) is rare. In previously reported patients with MS-induced parkinsonism, MS manifested first, followed a typical clinical course, and parkinsonism developed later in the course of the illness. We report a 52-year-old male presenting with parkinsonism as the initial manifestation of MS, in whom a subsequent MS relapse consisted of marked deterioration in parkinsonism, a clinical pattern not previously described in MS. A brain MRI demonstrated involvement of the substantia nigra and basal ganglia. This patient illustrates that the clinical presentation and progression of MS may rarely be characterised by predominating parkinsonian features which are reversible by treatment with intravenous methylprednisolone and interferon beta1a.