Global Warming Potential of Volatile Anaesthetics • hypercapnia

Introduction

The hypercapnia package offers functions to estimate the global warming potential of volatile anaesthetics based on values described in Ryan and Nielsen (2010).

Data

hypercapnia includes the ianes data with important key facts about frequently used anaesthetics.

library("hypercapnia")

knitr::kable(ianes)

Name	MAC	MW	Density	GWP20	GWP100	GWP500	Unit	Color
Desflurane	0.060	168.0	1.45	6810	2540	130	240	#3c4f8b
Isoflurane	0.012	184.5	1.49	1800	510	160	250	#9a2d80
Sevoflurane	0.020	200.0	1.52	508	144	43	250	#f8e620

Reproducing Table 2

In the next code snippet we reproduce the Table 2 of Ryan and Nielsen (2010). (The values slightly differ because of different precision and ounding errors).

i <- match(
    rep(c("Sevoflurane", "Isoflurane", "Desflurane"), c(1, 3, 3)),
    ianes$Name
)
fgf <- c(2, rep(c(0.5, 1, 2), 2))
gph <- gram_per_hour(mass = ianes$MW[i], mac = ianes$MAC[i], fgf = fgf)
cde20 <- cde_gram_per_hour(
    mass = ianes$MW[i], mac = ianes$MAC[i], gwp = ianes$GWP20[i], fgf = fgf
)
tbl2 <- data.frame(
    name = ianes$Name[i], mac = ianes$MAC[i] * 100, fgf = fgf,
    gph = gph, gwp20 = ianes$GWP20[i], cde20 = cde20,
    r = cde20 / cde20[1]
)
knitr::kable(
    tbl2,
    col.names = c(
        "Name", "et %", "FGF (L/min)", "Grams/hour", "GWP20", "CDE20 (g/h)",
        "Ratio CDE20"
    ),
    caption = paste0(
        "Comparison of Global Warming Impact of ",
        "Frequently Used Inhaled Anesthetics per MAC-Hour of Use at ",
        "Various Fresh Gas Flows; ",
        "MAC = minimal alveolar concentration; ",
        "et = endtidal;",
        "GWP20 = 20-year global warming potential; ",
        "CDE20 = 20-year carbon dioxide equivalent."
    ),
    digits = 1
)

Comparison of Global Warming Impact of Frequently Used Inhaled Anesthetics per MAC-Hour of Use at Various Fresh Gas Flows; MAC = minimal alveolar concentration; et = endtidal;GWP20 = 20-year global warming potential; CDE20 = 20-year carbon dioxide equivalent.
Name	et %	FGF (L/min)	Grams/hour	GWP20	CDE20 (g/h)	Ratio CDE20
Sevoflurane	2.0	2.0	20.0	508	10136.7	1.0
Isoflurane	1.2	0.5	2.8	1800	4970.1	0.5
Isoflurane	1.2	1.0	5.5	1800	9940.2	1.0
Isoflurane	1.2	2.0	11.0	1800	19880.3	2.0
Desflurane	6.0	0.5	12.6	6810	85609.4	8.4
Desflurane	6.0	1.0	25.1	6810	171218.8	16.9
Desflurane	6.0	2.0	50.3	6810	342437.6	33.8

Reproducing Figure 1

In the next code snippet we reproduce the Figure 1 of Ryan and Nielsen (2010).

# order in Ryan2010 Figure 1
o <- c(1, 7, 4)
barplot(
    setNames(tbl2$cde20[o], tbl2$name[o]),
    col = ianes$Color[match(tbl2$name[o], ianes$Name)],
    main = paste0(
        "Relative global warming impact of 1 MAC-hour of ",
        "3 inhaled anesthetics at 2 L fresh gas flow"
    ),
    ylab = expression(CDE[20]),
    sub = "CDE20 = 20-year carbon dioxide equivalent (in grams)"
)

References

Ryan, Susan M., and Claus J. Nielsen. 2010. “Global Warming Potential of Inhaled Anesthetics.” Anesthesia & Analgesia 111 (1): 92–98. https://doi.org/10.1213/ane.0b013e3181e058d7.