Table 1.
Demographics of 165 consecutive unselected PAVM patients.
Figure 1.
Basis of polycythaemia and anaemia responses in PAVM patients.
Univariate associations demonstrating individual patient data (small diamonds), linear regression lines, and 95% confidence intervals (shaded) for two way relationships. A–C): The polycythaemic response to hypoxaemia. A) Lower SaO2 was associated with higher haemoglobin (the ‘polycythaemic response’). B) This polycythaemia was not attributable to increased haemoglobin concentration in red cells (mean corpuscular haemoglobin concentration, MCHC). C) Instead, the polycythaemia reflected increased red cell number (RBC), that is, secondary erythrocytosis, D–F) The anaemic response to iron deficiency: D) Lower serum iron concentrations were associated with lower haemoglobin (the ‘anaemic response’). E) This anaemic response to iron deficiency resulted from reduced haemoglobin concentration in red cells (MCHC), and not a change in red cell number (RBC) (F).
Figure 2.
Three-way plots of relationships between haematinic indices and SaO2.
Three-way plots of relationships between SaO2 (y axis), ferritin/iron (x axis), and haematinic index (z axis). The most hypoxaemic patients are at the bottom of each graph, and patients with the lowest ferritin/iron levels to the left. The z axis effectively provides a 3 dimensional plot in which contours range from blue (lowest value of modelled haematinic variable) to red (highest values). A–D) Serum ferritin/SaO2 stratifications for the 105 PAVM patients with serum ferritin measurements: A) SaO2/ferritin/haemoglobin. B) SaO2/ferritin/haematocrit. C) SaO2/ferritin/MCHC. D) SaO2/ferritin/red cell count. Note that higher haemoglobin, haematocrit and MCHC are seen across the normal range for ferritin (10–150 or 20–300 µg/L, according to gender), but higher RBC number is only seen in patients with low or subnormal ferritin. E–H) Serum iron/SaO2 stratifications for the 141 PAVM patients with serum iron measurements. E) SaO2/iron/haemoglobin. F) SaO2/iron/haematocrit. G) SaO2/iron/MCHC. D) SaO2/iron/red cell count. Although serum iron and serum ferritin were correlated (Spearman rho 0.34, p = 0.006), serum iron did not show the same relationships with hematinic indices as serum ferritin (contrast A and E; B and F; C and G; D and H). The highest haematinic indices were observed with serum iron above the normal range (7–27 µmol/L).
Figure 3.
Arterial oxygen content stratified by oxygen saturation (SaO2).
Oxygen content across all degrees of hypoxaemia, calculated by SaO2 x haemoglobin x 1.34/100, where SaO2 was expressed as a %, and 1.34mls is the amount of oxygen carried per gram of haemoglobin.[1] The bold black line represents the regression line for all patients, irrespective of iron status (p = 0.69). Grey diamonds/dotted line/shaded 95% confidence interval represent patients without iron deficiency (p = 0.33). Red diamonds/dotted line/shaded 95% confidence interval represent patients with iron deficiency (p = 0.97).
Figure 4.
165 PAVM patients graded according to self-reported exercise tolerance.
A) SaO2 relationships. Error bars represent mean and standard deviation. Similar trends were observed for median and IQR (data not shown). B) Oxygen content, calculated by SaO2 x haemoglobin x 1.34/100, where SaO2 was expressed as a %, and 1.34mls is the amount of oxygen carried per gram of haemoglobin [1]. Error bars represent mean and standard deviation, but a similar trend was observed for median and IQR (data not shown).
Figure 5.
Boxplot comparisons of athletes and other individuals with normal exercise tolerance.
Individuals with normal exercise tolerance (Grade 1) were subclassified into Grade 1a (athletes, grey symbols/lines, if participating in intense sporting activity such as rowing, football, distance cycling or gym activities at least three times per week), and Grade 1b (other normals, red symbols/lines, if they described dyspnoea only on strenuous exertion). All assignments were made blinded to physiological parameters [44]. A) Haemoglobin (Hb) adjusted for SaO2, presented as (100*haemoglobin)/SaO2. Mann Whitney p value = 0.0059. P values were also calculated by Kruskal Wallis across all exercise grades, when Dunn's post test correction comparing the athletic and non athletic normals gave a p value of<0.05. B) Serum iron. Mann Whitney p value = 0.010. P values were also calculated by Kruskal Wallis across all exercise grades, when Dunn's post test correction comparing the athletic and non athletic normals gave a p value of<0.05.
Figure 6.
Blood oxygen content pre and post embolisation.
Post embolisation data were obtained at clinic follow up at a median of 7 months (range (2–24) months after the final embolisation. Shaded areas represent 95% confidence interval for quadratic regression line for all 52 patients with pre and post embolisation haemoglobin measurements (pseudo r2 0.44, p<0.0001). Open diamonds represent individuals with pre embolisation serum iron <4 µmol/L.
Table 2.
Changes in SaO2, haemoglobin, and oxygen content following PAVM embolisation.
Table 3.
Demographics, and univariate associations with improvement in exercise capacity post embolisation for the 98 PAVM patients.