Frequent situations of CO poisoning occur due to individual (gas-based) heating systems malfunction combined with thermopane windows that completely isolate the rooms.  

Relationship between enviromental CO concentration, HbCO concentration in blood and symptoms may vary among individuals, generic indications are represented in the table below (adapted from Okeda et.al., 1983):

These data refer to healthy individuals.

We still have to remember that pathologic conditions impairing tissue oxygen supply, like coronary atherosclerosis or pulmonary diseases, get the COHb concentration at which death may occur much lower, even to values of 30-40%.

Cut-off values are the minimum concentrations of drugs or metabolites that must be present in samples before a lab will report the testing result as positive.

In many countries there are no legal regulations to establish cut-off values for substances of abuse, thus each lab has to take the responsability for it's own positive results.

We present some cut-off values published by SAMSHA (Substance Abuse and Mental Health Services Administration):

1. Screeing by Immunoassay (IA):

• Marijuana metabolites: 50 ng/ml
• Cocaine metabolites: 150 ng/ml
• Opiate metabolites: 2000 ng/ml
• Phencyclidine:             25 ng/ml
• Amphetamines:         500 ng/ml

2. Confirmatory analysis by GC-MS:

• Marijuana metabolites: 15 ng/ml
• Cocaine metabolites: 100 ng/ml
• Opiate metabolites: 2000 ng/ml (6-acetylmorphine = 10ng/ml)
• Phencyclidine:             25 ng/ml
• Amphetamines:         250 ng/ml

Is a heart of 450 g normal or is there a subsequent pathological process that determined cardiac hypertrophy ?

The cutoff value for the heart weight depends upon pathologist's experience and information. There are several systems used, like the "500 g limit" - above this value a sudden death can be explained as heart-determined. Some pathologists even use 350 g or 400 g as maximum normal heart weights. J. Ludwig (1979) proposed percentages of body weight: 0.4% for men and 0.45% for women. A nomogram worked out by Kitzman and co-workers in 1988 (Mayo Clin Proc, 63) established normal heart weights (HW) related to gender, body height (BH) and body weight (BW):

• for men 170 cm tall, average HW is 312 g, with CI (95%) between 221-440 g
• for men 190 cm tall, average HW is 349 g, with CI (95%) between 250-498 g
• for men 100 kg BW, average HW is 391 g, with upper limit of 95% CI, 516 g
• for women of less than 111 kg, a HW of above 500 g is considered out of the normal range.