How Much Reduced Hemoglobin Is Necessary to Generate Central Cyanosis: LITERATURE SURVEY

16 Mar
2011

Of the ten original articles published after 1923, all but two reference the Lundsgaard and Van Slyke paper by footnote. Two of the ten articles erroneously compare an arterial value of RHB to the capillary value of Lundsgaard and Van Slyke.

One review article also makes this erroneous comparison and as a result states that the value of 5 g/dl is “incorrect.” Two other review articles err by placing the value of 5 g/dl RHB in the arterial circulation. None of the three errant review articles references the 1923 Lundsgaard and Van Slyke article.

A fourth review article notes that the capillary RHB value of Lundsgaard and Van Slyke and the arterial value quoted in “medical textbooks” are the same, but does not discuss or try to resolve the discrepancy. Four of eight review articles seem to provide a satisfactory discussion of RHB in cyano. Viagra Online Canadian Pharmacy

Table 1—Value of FaOt, SaOz, or Reduced Hemoglobin at Which Centred Cyanosis Is Detectable

Reference

Arterial Blood

Capillary Blood

Lundsgaard (1923)2

NS

RHB 5

Campbell (1923)7

Sa02<90%

NS

Brinkman (1938)8

Sa02<94%

NS

Bluhm (1942)®

SaOz<95%

NS

Comroe (1947)10

Most observers could not

t

detect cyanosis until

Sa02 80% or less

Geraci (1951)11

Definite: “Sa02 about 75%”

t

Medd (1959)12

Variable detection until

NS

Sa02 75% or less

Kelman (1966)”

Sa02<90%

NS

Morgan-Hughes (1968)14

Sa02 85-89%

NS

Barnett (1982)3

RHB 3.48 (mean)

NS

RHB 2.38 (threshold)

Goss (1988)4

RHB> = 1.50

NS

Cot6 (1988)15

Sa02< = 72%

NS

One recent letter, attempting to clarify the impor­tance of capillary RHB, confused the arterial and capillary Sa02 values in cyanosis; the reply to this letter did not clear up the confusion.

Of the 24 standard textbooks we examined, only one references the 1923 Lundsgaard and Van Slyke article, but it does not specify that the 5/dl RHB is in the capillaries. In fact, only eight of the 24 text- books, state a specific value for RHB and place it in the capillaries.
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