HYPOXEMIA AND HYPERCAPNIA

Objectives: to understand the diverse ways in which abnormal ventilation and pulmonary circulation can lead to inadequate oxygenation of arterial blood (arterial hypoxemia) and to carbon dioxide retention in the body (hypercapnia or hypercarbia).



In [37]:

    
def calculate_values(Vt, f, Vd, PACO2, PaO2):
    R = 0.8 # constant
    Ve = Vt * f
    Va = (Vt - Vd) * f
    PAO2 = 150 - (PACO2/R)
    Aagap = PAO2 - PaO2
    return (Ve / 1000.0, Va / 1000.0, PAO2, Aagap)



In [93]:

    
def print_info(Vt, f, Vd, PACO2, PaO2, SaO2100, DLCO):
    (Ve, Va, PAO2, Aagap) = calculate_values(Vt, f, Vd, PACO2, PaO2)
    if Aagap < 15:
        print "No A-a gap - ventilation problem"
        if Ve > 6.0:
            print "Ve (%.2f) is higher than normal" % (Ve)
            if Va < 4.2:
                print "Va (%.2f) is lower than normal" % (Va)
                print "*** Increased Vd (dead space) ***"
            else:
                print "Va (%.2f) is higher than normal" % (Va)
                print "*** Hypoxia ***"
        else:
            print "Low Ve (%f) - Insufficient breathing" % (Ve)
    else:
        print "A-a gap (%.2f) - distribution problem" % (Aagap)
        if SaO2100 < 100:
            print "*** Shunt ***"
        else:
            if DLCO >= 25 and PAO2 > 100:
                print "*** V/Q mismatch ***"
            else:
                print "*** Diffusion limitation ***"



In [95]:

    
print "CASE 1: Asthma" 
print "Quiet breathing"
print_info(600, 16, 160, 38, 95, 100, 38)
print "\nAsthmatic breathing"
print_info(600, 16, 160, 30, 78, 100, 38)









    



CASE 1: Asthma
Quiet breathing
No A-a gap - ventilation problem
Ve (9.60) is higher than normal
Va (7.04) is higher than normal
*** Hypoxia ***

Asthmatic breathing
A-a gap (34.50) - distribution problem
*** V/Q mismatch ***



In [96]:

    
print "CASE 2: Pulmonary hemangioma"
print_info(730, 23, 150, 32, 56, 91, 0)









    



CASE 2: Pulmonary hemangioma
A-a gap (54.00) - distribution problem
*** Shunt ***



In [98]:

    
print "CASE 3: Interstitial Fibrosis"
print_info(430, 20, 150, 34, 52, 100, 6)









    



CASE 3: Interstitial Fibrosis
A-a gap (55.50) - distribution problem
*** Diffusion limitation ***



In [99]:

    
print "CASE 4: Obstructive emphysema"
print_info(500, 10, 160, 32, 59, 100, 5.5)









    



CASE 4: Obstructive emphysema
A-a gap (51.00) - distribution problem
*** Diffusion limitation ***



In [100]:

    
print "Question 3 Quiz"
print_info(370, 24, 270, 62, 57, 100, 30)









    



Question 3 Quiz
A-a gap (15.50) - distribution problem
*** Diffusion limitation ***