Portable oxygen therapy: assessment and usage

Fifty portable oxygen assessments, based on 6-min walking tests, were reviewed to produce guidelines for assessment and prescription of portable oxygen, and to evaluate factors predicting benefit. Patients with a portable cylinder were questioned about benefits/difficulties and usage of portable oxygen. A significant improvement on the oxygen compared to the air walk was found (median 9.7%) which correlated with the oxygen desaturation on the baseline walk (r = 0.51, P less than 0.05). A placebo effect was demonstrated using an air cylinder (median improvement 6.1%). There was no correlation between improvement in walking distance and decrease in visual analogue scale (VAS) score of breathlessness. We recommend standard portable oxygen assessments based on a series of 6-min walks. Improvements of 10% in walking distance or VAS score from the oxygen to the air walk would lead to the patient being offered a portable oxygen cylinder.

Increased platelet aggregate formation in patients with chronic airflow obstruction and hypoxaemia

Platelet aggregate formation in vivo was assessed by means of the platelet aggregate ratio and from platelet release products (beta thromboglobulin, platelet factor 4, thromboxane B2) in 23 patients with chronic airflow obstruction with and without hypoxaemia and in 10 control subjects without respiratory disease. Eight of the 11 hypoxaemic patients were having long term oxygen therapy. The platelet aggregate ratio was lower in the hypoxaemic patients (0.88 (SE 0.03] than in the non-hypoxaemic (0.97 (0.01] and control groups (1.00 (0.02], and there was a trend to lower aggregate ratios in the more hypoxaemic patients. Platelet release products in the peripheral venous blood were not increased in the patients or control subjects. Platelet behaviour is altered in chronic hypoxaemia and this enhanced platelet activity could contribute to the pulmonary vascular damage found in these patients through direct effects or mediator release.

Overnight studies in severe chronic left heart failure: arrhythmias and oxygen desaturation

Overnight studies were performed in 10 patients with severe chronic left heart failure (New York Heart Association grades III and IV) without pulmonary disease and in eight controls. Transcutaneous oxygen (Po2) and carbon dioxide tensions (Pco2) and oxygen saturation were measured and the electro-cardiogram was recorded. During sleep mean oxygen saturation fell to 92.7% (minimum 86.1%) from 95.1% when awake. During the night oxygen saturation was below 95% for 62% of the time, below 90% for 6% of the time, and below 85% for 1% of the time. In four patients there were oxygen desaturation dips (a fall of greater than 4% in oxygen saturation from a stable baseline that lasted greater than 30 s) with concurrent increases in Pco2. Two patients had bradycardia during the dips: in one there was non-sustained ventricular tachycardia during the dips and in the other there was ST depression (greater than 0.1 mV at 80 ms after the J point) during a dip. In the controls the fall in mean oxygen saturation from 95.4% when they were awake to 94.4% when they were asleep was less than the fall in patients with heart failure and there were no desaturation dips or arrhythmias. Thus patients with severe heart failure had episodes of oxygen desaturation during sleep, some of which were associated with arrhythmia. Such episodes may be related to the increased risk of sudden death in chronic heart failure.

Pulmonary microvascular permeability in patients with severe mitral stenosis

Patients with rheumatic mitral stenosis often have no pulmonary oedema despite considerably increased pulmonary venous pressure. Pulmonary microvascular permeability was measured non-invasively by a previously validated method of double isotope scintigraphy with indium-113m and technetium-99m. This permits calculation of an index reflecting transferrin efflux and thus, indirectly, the microvascular permeability. Fifteen patients with severe mitral stenosis (defined as valve area less than 1.0 cm2) were compared with a control group of 11 patients with mild coronary artery disease. The permeability index was significantly lower in patients with mitral stenosis than in the control group. Furthermore, the extent of reduction of the permeability index correlated with the severity of mitral stenosis as reflected by the Gorlin valve area. This finding may account for the relative resistance of these patients to pulmonary oedema despite chronic pulmonary venous hypertension.

Sarcoidosis presenting with stroke

A 25-year-old black man with sarcoidosis presented with transient ischemic attacks followed by sudden, persistent right hemiparesis. He gave a history of recent, recurrent lower motor neuron facial palsy. Computed tomography demonstrated an infarct in the left internal capsule. Chest x-ray film showed bilateral hilar and mediastinal lymphadenopathy and multiple opacities in the lung fields. Serum angiotensin converting enzyme concentration was raised, and a Kveim test was positive for sarcoidosis. Despite clear pathologic reports of cerebral vasculitis in neurosarcoidosis, the occurrence of stroke is extremely rare.

Effect of diazepam on sleep in patients with chronic airflow obstruction

The effect of a single dose of diazepam on sleep and respiration was studied in nine patients with chronic airflow obstruction with moderate arterial hypoxaemia but no hypercapnia. Diazepam improved sleep duration without exacerbating nocturnal hypoxaemia and there was no change in the number of apnoeic events after a single 5 mg dose at night.

Platelet size in patients with chronic airflow obstruction with and without hypoxaemia

Platelet size, expressed as mean platelet volume, was estimated in 35 patients with chronic airflow obstruction and a wide range of arterial oxygen tension (PaO2) values. In these patients there was a negative correlation between MPV and PaO2 (r = -0.70). Mean platelet volume was greater (9.41 (0.86) fl) in 20 patients with an arterial PaO2 of 8 kPa (60 mm Hg) or less than in 18 normal subjects (8.21 (0.63) fl; p less than 0.001). After 24 hours of supplemental oxygen treatment there was a small fall in mean platelet volume, from 9.47 (1.06) to 8.96 (0.8) fl (p less than 0.05) in 12 hypoxaemic patients (PaO2 breathing air less than or equal to 8 kPa) but no change in nine non-hypoxaemic patients. Larger platelets are considered to be haemostatically more active, leading to abnormal platelet function, which may contribute to the development of pulmonary vascular damage in chronic hypoxaemia. Supplemental oxygen may partially reverse these changes by modifying platelet size and activity.

Effects of erythrapheresis on pulmonary haemodynamics and oxygen transport in patients with secondary polycythaemia and cor pulmonale

Reducing packed cell volume has been advocated as a therapeutic procedure in patients with polycythaemia secondary to hypoxic cor pulmonale. The aim of this investigation was to evaluate the effects of this manoeuvre on resting pulmonary haemodynamics and tissue oxygenation in 12 such patients. The subjects were studied whilst they were breathing air (n = 12), after breathing 35% oxygen for 30 min (n = 11) and breathing air 30 min after isovolaemic reduction in packed cell volume, from 0.61 +/- 0.02 to 0.50 +/- 0.02 (mean +/- SEM), by erythrapheresis (n = 12). Initial values for the group were: PaO2 6.5 +/- 0.3 kPa; red cell mass 152 +/- 12% predicted; mean pulmonary artery pressure (PAP) 41 +/- 3 mmHg; cardiac index 3.1 +/- 0.31 min-1 m-2. Breathing 35% oxygen reduced PAP by 3.1 +/- 1.0 mmHg (P less than 0.02), cardiac index by 0.28 +/- 0.121 min-1 m-2 (P less than 0.05) and right ventricular stroke work by 0.05 +/- 0.01 J (P less than 0.01). Systemic vascular resistance was unchanged. Systemic oxygen transport increased and peripheral oxygen consumption was unaltered. Erythrapheresis reduced blood viscosity at shear rates 23 S-1 and 230 S-1. PAP fell by 2.4 +/- 1.1 mmHg (P less than 0.05) and cardiac index increased by 0.32 +/- 0.091 min-1 m-2 (P less than 0.01), but right ventricular stroke work was unchanged. Systemic vascular resistance was reduced by 25 +/- 7 kPa S l-1 (P less than 0.01). Systemic oxygen transport decreased but peripheral oxygen consumption was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum immunoreactive erythropoietin in hypoxic lung disease with and without polycythaemia

We studied 20 patients with chronic airflow obstruction, 10 patients without polycythaemia and 10 patients with compensatory polycythaemia having respectively mean red cell mass 24.7 (SD 4.2) and 47.8 (SD 7.5) ml/kg, mean daytime PaO2 7.6 and 6.9 kPa, mean FEV1 0.85 and 0.821. Groups were matched for severity of daytime arterial hypoxaemia but nocturnal arterial oxygen desaturation was more severe in the patients with polycythaemia than in those without. We also studied six additional patients with chronic airflow obstruction and polycythaemia and 19 normal controls. Estimates of serum immunoreactive erythropoietin (siEp) in those without polycythaemia were 19 m-i.u./ml (geometric mean) with 95% confidence range 11-35 m-i.u./ml and stable during 3 months. In those with polycythaemia they were similar and consistent in five and, in the other five, higher on at least one occasion. There was no significant difference between siEp in daytime (12.00 hours to 16.00 hours) and morning (07.00 hours) samples but geometric mean estimates of erythropoietin in paired daytime and morning samples were higher and more variable in patients with polycythaemia than in those without. The geometric mean estimate of siEp in all patients with chronic airflow obstruction and polycythaemia was greater than in normal subjects but, despite secondary polycythaemia, siEp could be in the range for normal subjects. In the patients with polycythaemia we were unable to predict the finding of normal or elevated siEp. Changes in siEp after erythrapheresis (10-26% reduction in packed cell volume) were observed in the 10 patients with polycythaemia and in one without. One month after erythrapheresis, packed cell volume remained below and siEp was above initial pretreatment levels, implying an erythropoietin secretory response and that the development of secondary polycythaemia had induced a fall in siEp.

Gas transfer for carbon monoxide in polycythaemia secondary to hypoxic lung disease

The transfer factor for carbon monoxide and its subdivisions, the membrane diffusing capacity (Dm) and the pulmonary capillary blood volume (Vc), were measured in 16 patients with polycythaemia secondary to chronic hypoxic lung disease and in ten hypoxic non-polycythaemic control subjects. The mean pulmonary capillary blood volume was significantly lower in the polycythaemic patients (31.6 ml, SD 11.2) compared with the control group (65.2 ml, SD 22.5) (P less than 0.001). Erythrapheresis, as a method of isovolaemic haemodilution, was performed in 15 of the polycythaemic patients. The mean packed cell volume fell from 58 (SD 5)% to 47 (SD 5)% after treatment, with significant reductions in blood viscosity at both high and lower shear rates (P less than 0.001). The mean pulmonary capillary blood volume increased from 32.3 ml (SD 11.3) before treatment to 48.7 ml (SD 18.7) after erythrapheresis (P less than 0.01), with no significant change in membrane diffusing capacity. The rise in pulmonary capillary blood volume is another potential physiological advantage of the reduction of packed cell volume in patients with polycythaemia secondary to hypoxic lung disease.

Erythrapheresis compared with placebo apheresis in patients with polycythaemia secondary to hypoxic lung disease

We have assessed the effects of erythrapheresis, a method of isovolaemic haemodilution, and placebo apheresis in 10 patients with polycythaemia secondary to chronic hypoxic lung disease (Mean PaO2 7.2kPa (54 mm Hg]. The mean packed cell volume decreased from 0.60 to 0.48, with significant decreases in blood viscosity at both high and low shear rates (p less than 0.001). The 6-min walking distance improved after erythrapheresis with no significant placebo effect of the procedure compared to control subjects (p less than 0.01). Erythrapheresis is a safe procedure for packed cell volume reduction. It is associated with clinical improvement and there is no demonstrable placebo effect on exercise tolerance.

Chorea in digoxin toxicity

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Erythrapheresis in patients with polycythaemia secondary to hypoxic lung disease

Erythrapheresis was performed in 10 patients with polycythaemia secondary to hypoxic lung disease (mean PaO2, 6.8 kPa (51 mm Hg)). The mean packed cell volume decreased from 0.64 to 0.48 in men and from 0.56 to 0.42 in women, with significant decreases in blood viscosity at both high and low shear rates (p less than 0.001). Patients showed significant improvement in six-minute walking distances (p less than 0.001) and in tests of mental alertness (p less than 0.01) compared to control subjects. Visual analogue scales confirmed symptomatic improvement after erythrapheresis. Erythrapheresis significantly improved symptoms, mental function, and work performance in patients with polycythaemia secondary to hypoxic lung disease. The procedure was well tolerated by all patients and no complications occurred.

Small intestinal perforation in Wegener's granulomatosis

A case of Wegener's granulomatosis complicated by small bowel ulceration and perforation is described. Following laparotomy, with bowel resection, haemodialysis and immunosuppressive therapy, a full recovery was achieved including reversal of severe renal failure.