Fully extending the concertina tubing of a breathing circuit reduces compliance: the rigidity of the tubing itself falls, and there is more air in it. The following chart shows the effect of this difference on dead-space fraction in neonatal ventilation. This shows why a compliance test is essential before a neonatal anesthesia case, and why the tubing should not be extended or contracted after this test.
# units of ml per cmH20
min_compliance <- 0.5
max_compliance <- 1.5
# unit cmH20
driving_pressure <- 15
insp_tube_vol_diff <- driving_pressure * (max_compliance - min_compliance)
Get median female weight for age up to one year.
dat <- as_tibble(
childsds::make_percentile_tab(
childsds::who.ref,
item = "weight",
perc = 50,
stack = TRUE,
sex = "sex"))
dat <- dplyr::filter(dat, sex == "female", age <= 1) %>%
dplyr::rename(weight = value) %>%
dplyr::select(age, weight)
dat <- dat %>%
mutate(tidal_volume = 7 * weight) %>%
mutate(error_fraction = insp_tube_vol_diff / tidal_volume)
plot(dat[c("weight", "error_fraction")], type = "l")