scuba (version 1.1-9)

haldane: Tissue Saturation by Haldane Model

Description

Computes a diver's nitrogen saturation during and after a dive, as predicted by a Haldane model.

Usage

haldane(d,
	 halftimes={ data(Halftimes); Halftimes$DSAT}, 
	 prevstate=rep(0.79,length(halftimes)),
         progressive=FALSE)

Arguments

d

The dive profile. An object of class dive.

halftimes

Vector of halftimes for the tissues (compartments) in the Haldanean model. Defaults to the values for the DSAT (PADI) model.

prevstate

The diver's nitrogen saturation state at the beginning of the dive, for repetitive dives. Default is to assume the diver is ``desaturated'' (in equilibrium with air at sea level) at start of dive.

progressive

Logical flag. If TRUE, the tissue saturations are computed at every time point during the dive. If FALSE, only the final tissue saturation at the end of the dive is computed.

Value

• If progressive=FALSE, a vector giving the diver's nitrogen saturation state at the end of the dive. Each entry is the nitrogen tension (in atmospheres absolute) of the compartment.

  If progressive=TRUE, a data frame giving the diver's nitrogen saturation state at each time point during the dive. The rows of the data frame correspond to successive time points during the dive (the times can be extracted by times.dive). The columns correspond to the tissue compartments. The entries are nitrogen tensions (in atmospheres absolute).

Warnings

Not applicable to altitude dives. Not applicable to gas mixtures other than air and nitrox (oxygen-nitrogen mixtures).

Details

Henry's Law is applied to predict the on- and off-gassing of nitrogen in each tissue (compartment) of the model. The resulting differential equations are solved analytically. No constraints of any kind are checked. In particular the M-values of the model are not used, so it is not guaranteed that the model accepts the dive profile as a no-decompression dive.

See Also

dive, oxtox

Examples

# First dive to 25 m for 20 min with safety stop
  d1 <- dive(c(25,20),c(5,5))
  # Evaluate saturation according to DSAT model
  s1 <- haldane(d1)
  # Look at saturation (in ata)
  barplot(s1)
  # Look at saturation (in \% of maximum)
  data(Mvalues)
  barplot(100 * s1/Mvalues$ata$DSAT, ylab="Relative saturation", xlab="Tissues")
  # Evaluate saturation after 2 hour surface interval
  s2 <- haldane(dive(c(0,120)), prevstate=s1)
  # Then after another dive to 18 m for 30 min with safety stop
  s3 <- haldane(dive(c(18, 30),c(5,3)), prevstate=s2)
  # Assess effect of breathing 80\% oxygen at safety stop
  s3o <- haldane(dive(c(18, 30),5, nitrox(0.8), c(5,3)), prevstate=s2)