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. 2015 Apr;193(2):183-7.
doi: 10.1007/s00408-015-9686-x. Epub 2015 Feb 14.

Carboxyhemoglobin and methemoglobin in asthma

Robert Naples  1 , Dan Laskowski, Kevin McCarthy, Emmea Mattox, Suzy A A Comhair, Serpil C Erzurum
Affiliations

Carboxyhemoglobin and methemoglobin in asthma

Robert Naples et al. Lung. 2015 Apr.

Abstract

Nitric oxide (NO) and carbon monoxide (CO) are synthesized at high levels in asthmatic airways. NO can oxidize hemoglobin (Hb) to methemoglobin (MetHb). CO binds to heme to produce carboxyhemoglobin (COHb). We hypothesized that MetHb and COHb may be increased in asthma. COHb, MetHb, and Hb were measured in venous blood of healthy controls (n = 32) and asthmatics (n = 31). Arterial COHb and oxyhemoglobin were measured by pulse CO-oximeter. Hb, oxyhemoglobin, and deoxyhemoglobin were similar among groups, but arterial COHb was higher in asthmatics than controls (p = 0.04). Venous COHb was similar among groups, and thus, arteriovenous COHb (a-v COHb) concentration difference was greater in asthma compared with controls. Venous MetHb was lower in asthma compared to controls (p = 0.01) and correlated to venous NO (p = 0.009). The greater a-v COHb in asthma suggests CO offloading to tissues, but lower than normal MetHb suggests countermeasures to avoid adverse effects of high NO on gas transfer.

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Figures

Figure 1
Figure 1
[A] Arterial and venous COHb among asthmatics and healthy controls. Asthmatics have higher arterial levels of COHb than controls. [B] a-v COHb differences are greater in asthma (P=0.02). Mean values and standard error are shown.
Figure 1
Figure 1
[A] Arterial and venous COHb among asthmatics and healthy controls. Asthmatics have higher arterial levels of COHb than controls. [B] a-v COHb differences are greater in asthma (P=0.02). Mean values and standard error are shown.
Figure 2
Figure 2
[A] Venous MetHb is lower in asthmatics as compared to healthy controls. [B] Venous NO is similar among asthmatics and controls. Mean values and standard error are shown. Each dot represents an individual measure.
Figure 2
Figure 2
[A] Venous MetHb is lower in asthmatics as compared to healthy controls. [B] Venous NO is similar among asthmatics and controls. Mean values and standard error are shown. Each dot represents an individual measure.
Figure 3
Figure 3
Relationship between venous NO and venous MetHb in asthma.
See this image and copyright information in PMC

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