The use of automated strain gauge plethysmography in the diagnosis of deep vein thrombosis.

The venometer is a nurse- or technician-operated machine that uses automated strain gauge plethysmography to detect deep vein thrombosis (DVT). We compared the venometer with contrast venography to determine its accuracy, and also used it to triage patients between admission with subsequent anticoagulation and out-patient investigation without anticoagulation. We enrolled 307 consecutive patients presenting to the medical admissions unit with suspected DVT, of whom 270 underwent both plethysmography and venography. Plethysmography produced a negative predictive value (NPV) of 97% and a sensitivity of 90% for proximal DVT. It also produced a false negative rate of 10% for proximal DVT, For distal DVT, sensitivity was 66%, specificity 80%, positive predictive value 36% and NPV 93%. We conclude that the automated venometer report is a quick, non-invasive and easy to use initial screening test. However, it is not sufficiently accurate in a medical admissions unit to be a definitive diagnostic test for DVT and may, therefore, be best used in combination with clinical risk assessment and D-dimer assay with more definitive radiological investigations as necessary.

A case of congenital central hypoventilation syndrome in a three-generation family with non-polyalanine repeat PHOX2B mutation.

We describe a three generation family in whom multiple individuals are variably affected due to a PHOX2B non-polyalanine repeat mutation. This family demonstrates extreme phenotypic variability and autosomal dominant transmission over three generations not previously reported in the wider literature. Novel findings also inclue a history of recurrent second trimester miscarriage. Pediatr Pulmonol. 2014; 49:E140-E143. © 2014 Wiley Periodicals, Inc.

Comparison of pressure and volume preset nasal ventilator systems in stable chronic respiratory failure.

Nasal intermittent positive pressure ventilation (NIPPV) has been widely used in the treatment of chronic respiratory disease. Ventilators may be volume or pressure preset; each type has theoretical advantages, but to date there has been no formal comparison. We wanted to assess the efficacy on blood gas changes that may be achieved and overall acceptability of four nasal ventilators (two pressure preset: Respironics bilevel positive airway pressure (BiPAP) and the Thomas NIPPY; and two volume preset: BromptonPac and Monnal-D) in patients with stable chronic respiratory failure. Median age was 59 yrs (range 48-71 yrs), mean (SD) arterial oxygen tension (PaO2) 7.16 (0.21) kPa, arterial carbon dioxide tension (PaCO2) 7.02 (0.35) kPa, forced expiratory volume in one second (FEV1) 0.76 (0.24) l, and forced vital capacity (FVC) 1.58 (0.49) l. All had previously used NIPPV. There were significant changes in blood gases at 2 h with each ventilator: mean change (95% confidence interval); BiPAP PaO2 +1.52 (0.95-2.09) kPa, PaCO2-1.04 (1.55-0.54) kPa; NIPPY PaO2 +1.63 (0.85-2.41) kPa, PaCO2, -1.1 (1.86-0.34) kPa; BromptonPac PaO2 +1.22 (0.75-1.67) kPa, PaCO2 -1.14 (1.52-0.76) kPa; Monnal-D PaO2 +1.14 (0.42-1.84) kPa, PaCO2 -1.19 (2.14-0.23) kPa. Analysis of variance showed no significant differences in the efficacy of volume or pressure preset equipment, and all ventilators proved equally acceptable to the patients studied. We conclude that all four of the volume or pressure preset ventilators examined are suitable for the delivery of nasal intermittent positive pressure ventilation in patients with stable chronic respiratory failure.

Nasal pressure support ventilation plus oxygen compared with oxygen therapy alone in hypercapnic COPD.

Non-invasive ventilation has been used in chronic respiratory failure due to chronic obstructive pulmonary disease (COPD), but the effect of the addition of nasal positive-pressure ventilation to long-term oxygen therapy (LTOT) has not been determined. We report a randomized crossover study of the effect of the combination of nasal pressure support ventilation (NPSV) and domiciliary LTOT as compared with LTOT alone in stable hypercapnic COPD. Fourteen patients were studied, with values (mean +/- SD) of Pao2 of 45.3 +/- 5.7 mm Hg, PaCO2 of 55.8 +/- 3.6 mm Hg, and FEV1 of 0.86 +/- 0.32 L. A 4 wk run-in period (on usual therapy) was followed by consecutive 3-mo periods of: (1) oxygen therapy alone, and (2) oxygen plus NPSV in randomized order. Assessments were made during run-in and at the end of each study period. There were significant improvements in daytime arterial PaO2 and PaCO2, total sleep time, sleep efficiency, and overnight PaCO2 following 3 mo of oxygen plus NPSV as compared with run-in and oxygen alone. Quality of life with oxygen plus NPSV was significantly better than with oxygen alone. The degree of improvement in daytime PaCO2 was correlated with the improvement in mean overnight PaCO2. Nasal positive-pressure ventilation may be a useful addition to LTOT in stable hypercapnic COPD.

Nasal ventilation in acute exacerbations of chronic obstructive pulmonary disease: effect of ventilator mode on arterial blood gas tensions.

BACKGROUND: There are no controlled trials of the use of different modes of nasal intermittent positive pressure ventilation (NIPPV) in patients with exacerbations of chronic obstructive pulmonary disease (COPD). This study describes the effect on blood gas tensions of four different modes of nasal ventilation. METHODS: Twelve patients with acute exacerbations of COPD were studied (mean (SD) FEV1 0.59 (0.13) l, PaO2 (air) 5.10 (1.12) kPa, PaCO2 9.28 (1.97) kPa, pH 7.32 (0.03)). Each patient underwent four one-hour periods of nasal ventilation in randomised order: (a) inspiratory pressure support 18 cm H2O; (b) pressure support 18 cm H2O+positive end expiratory pressure (PEEP) 6 cm H2O (IPAP+EPAP); (c) continuous positive airway pressure (CPAP) 8 cm H2O; and (d) volume cycled NIPPV. Arterial blood samples were obtained before each period of ventilation and at one hour. RESULTS: Pressure support, CPAP, and volume cycled NIPPV all produced significant improvements in PaO2; there was no difference between these three modes. The change in PaO2 with IPAP+EPAP did not reach statistical significance. None of the modes produced significant changes in mean PaCO2; patients with higher baseline levels tended to show a rise in PaCO2 whereas those with lower baseline levels tended to show a fall. CONCLUSIONS: Although PaO2 improved in all patients there are differences in efficacy between the modes, while the changes in PaCO2 were variable. The addition of EPAP conferred no advantage in terms of blood gas tensions.

Using nasal intermittent positive pressure ventilation on a general respiratory ward.

OBJECTIVES: To assess the use of nasal intermittent positive pressure ventilation (NIPPV) in treating acute-on-chronic respiratory failure in a general medical ward. DESIGN: Retrospective analysis of clinical outcome. SETTING: A general medical ward of a tertiary respiratory medicine referral centre. SUBJECTS: Altogether 75 patients admitted with acute exacerbations of chronic respiratory failure and treated NIPPV. MAIN OUTCOME MEASURES: Blood gas tensions determined at admission to hospital and during NIPPV, tolerance of NIPPV and mortality. RESULTS: During treatment with NIPPV, the mean (SD) PaO2 increased rapidly by 2.31 (3.58) kPa (p < 0.0001), while the mean PaCO2 fell by 1.07 (1.74) kPa (p < 0.0001) and the mean pH increased by 0.03 (0.07) (p = 0.001). Altogether 57 (76%) of patients tolerated NIPPV, and (9.3%) died in hospital. Improvement in PaO2 was more noticeable in patients with chronic obstructive pulmonary disease (+3.13 (3.49) kPa, p < 0.0001) than in those with restrictive chest wall disease (+1.20 (3.07) kPa, p = 0.25) or obstructive sleep apnoea (+0.18 (3.64), p = 0.88). The reduction in PaCO2 was similar in all three groups. CONCLUSIONS: In routine treatment of unselected patients with acute-on-chronic respiratory failure who are being cared for on a general ward, NIPPV rapidly improves hypoxaemia and hypercapnia, is well tolerated and is associated with low mortality.