Acid Base Nomogram

References

• Grogono's Acid Base Tutorial

import numpy as np
import matplotlib.pyplot as plt

xpH = np.linspace(6.8,8.0,13)
xpH

array([6.8, 6.9, 7. , 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8. ])

# pH 7.4 = log10(1/H) = -log10(h) where h is Hydrogen ion in 40 nanomol/L
def calcPhFromH(h):
    return -np.log10(h)

# returns result in nanoMol/L (10e-7)
def calcHfromPh(p):
    return np.round( (1/10**p)*10e8,0)

def calcBicarb(pCO2,h):
    k = 24
    return pCO2 * k/h

# h is nanoMol/L
xh = calcHfromPh(xpH)
xh

array([158., 126., 100.,  79.,  63.,  50.,  40.,  32.,  25.,  20.,  16.,
        13.,  10.])

yCO2 = np.linspace(10,120,12)
yCO2

array([ 10.,  20.,  30.,  40.,  50.,  60.,  70.,  80.,  90., 100., 110.,
       120.])

fig = plt.figure(figsize=(8,8), dpi=150)

#normal pH
plt.plot([7.4,7.4],[0,60],'--',color='silver')
#normal bicarb
plt.plot([6.8,8.0],[24,24],'--',color='silver')
#buffer line
plt.plot([6.8,8.0],[34,15],'--',color='silver')
plt.text(7.9,15, 'Buffer\nLine', fontsize=10, color="gray")


plt.xticks(xpH) 
plt.yticks(np.arange(0,61.0,step=5)) 
plt.grid(color='whitesmoke',which='major', linestyle='-', linewidth=0.5)

for pCO2 in yCO2[::-1]:
    yBicarb = calcBicarb(pCO2,xh)
    plt.plot(xpH, yBicarb, label="CO2=%s" %(pCO2))
    

background_alpha = 1

#plot respiratory acidosis
plt.fill([6.8,7.4,7.4,6.8],[60,60,24.5,34],color="lightcoral",alpha=background_alpha)
plt.text(7.07, 55, 'Respiratory\nAcidosis', fontsize=15, color="white")
plt.text(7.0,32, 'Acute', fontsize=15, color="white")
plt.text(7.22,40, 'Chronic', fontsize=15, color="white")


#plot respiratory alkalosis
plt.fill([7.4,7.4,8.0,8.0],[0,24.5,15,0],color="lightgreen",alpha=background_alpha)
plt.text(7.6,2, 'Respiratory\nAlkalosis', fontsize=15, color="white")
plt.text(7.8,10, 'Acute', fontsize=15, color="white")
plt.text(7.45,10, 'Chronic', fontsize=15, color="white")

#plot Metabolic alkalosis
plt.fill([7.4,7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.],[60,24.5, 30.,38,48.,60.,74.,96.],color="lightblue",alpha=background_alpha)
plt.text(7.5, 55, 'Metabolic\nAlkalosis', fontsize=15, color="white")


#plot Metabolic acidosis
plt.fill([6.8, 6.9, 7., 7.1, 7.2, 7.3 ,7.4,7.4, 6.8],[6.,7.6,9.6, 12, 15,19,24.5,0,0],color="violet",alpha=background_alpha)
plt.text(6.9,2, 'Metabolic\nAcidosis', fontsize=15, color="white")


    
plt.legend()
plt.xlabel('pH')
plt.ylabel('Bicarbonate (HCO3-)')
plt.title('Acid-Base Nomogram (by Fpnotebook.com)')
plt.axis([6.8,8.0,0,60])

plt.savefig("acidBaseNomogram.svg")