CBAC: A COMPUTERIZED BLOOD ALCOHOL CONCENTRATION PROGRAM TO BE USED AS A CLINICAL AND AN EDUCATIONAL TOOL.

Transcription

1 CBAC: A COMPUTERIZED BLOOD ALCOHOL CONCENTRATION PROGRAM TO BE USED AS A CLINICAL AND AN EDUCATIONAL TOOL. Bhushan M Kapur, Addiction Research Foundation, 33 Russell St, Toronto (Ont) M5S 2S1, and Dept, of Clin Biochem, Faculty of Medicine, U. of Toronto, Canada. Alcohol is consumed in large amounts in most societies. It is a major cause of illness and injury. Most countries have a "legal" limit for BAC (Blood Alcohol Concentration). If caught operating a motor vehicle above this limit, the driver can be charged with "impairment" by the law enforcement authorities. Regular drinking can lead to tolerance. Tolerance makes the recognition and control of the amount of alcohol consumed, difficult. Estimation of BAC is often done for an education, forensic and research purposes. Law enforcement officials use cards which have graduated scales based on weight and number of drinks for the estimation of BAC. "Slide Rules" of various types have been available to do these calculations. Generally body weight and a factor varying between 0.58 to 0.68 to correct for total body water (TBW) is used in the development of the slide rule. Alcohol elimination rates are held constant at 15mg/100ml/hr. Size of the drink is often defined in generic terms such as 1 drink = 1 oz liquor or 1 drink = 1 1/2 oz liquor. Actual concentration of the alcoholic beverage can vary thus effecting the actual amount of alcohol consumed. Factors such as sex, height and age are not accounted for. Watson et al [1] have shown that both age and sex are important determinants in the calculations of total body water. As the age, in the male, increases the total body water content decreases. In the female, however, the difference is insignificant [..]. They have also shown that height is an important variable, albeit its contribution is small. Thus in order to calculate accurately total body water, age, sex, height and weight should be considered. Not including these variables would result in incorrect TBW content. Alcohol distributes itself in total body water. Thus not accounting for the various factors that are important in the calculation of TBW will result in an inaccurate estimation of BAC. We have developed a computer program which takes all the above mentioned variables into account in the calculations and estimation of BAC. CBAC (COMPUTERIZED BLOOD ALCOHOL CALCULATOR) is a computerized programme to calculate BAC. CBAC uses the local legal limits as "marker" of impairment since the general public usually relates to this level easily. CBAC is flexible and has many options. It was developed in the Microsoft DOS environment using Pascal as the programming language. In CBAC, the regression equation developed by Watson et.al is used to calculate the TBW. CBAC is a menu driven program and requires the input on sex, weight (kg or lbs), height (ft & in or cm) and age (for male) to do the calculations The programme takes the user through different menu options (scenarios) (Fig. 1) to make a selection. In one of its options, CBAC projects how many drinks can be consumed to remain below the various legal levels (Fig. 2). CBAC is an educational program. The user can go to the bar and have his/her usual number of drinks. Since CBAC is personalized to the users' vital statistics, it projects BAC depending on how much and over what period the 759

2 alcoholic beverage was consumed. The user can change the type, number and size of the drinks and see the effects on BAC. In the CBAC programme the user can customize their "bar" by specifying the type of drink, concentration and size (volume) of each serving. Elimination of alcohol, in most cases, is shown graphically for ease of interpretation. CBAC has two educational goals: 1. To reduce alcohol consumption through education. The program does this by using the "legal" limits as a guide to impairment. It shows how many hours were needed to fall below this limit. By varying the type, size and concentration of the drink, changes in BAC can be demonstrated. It can be used in the "home" environment where the host or hostess can pre-define the "bar menu" with the type and size of the drink. Hopefully, there after, the drinks will be "measured" rather than "poured". In the commercial environment, such as a restaurant or bar, CBAC menu could be tailored to reflect the local bar menu. The visiting patrons could use this, as a guide to monitor their drinking. Both in Canada and USA, the server of alcoholic beverage is legally responsible for "accidents" that may happen to the person who was served the alcoholic beverage. CBAC can be used by the servers of alcohol to gauge the amount they are allowed to serve. Using the graphical display (Fig. 3) it can be shown to the consumers of alcohol, that their BAC may well exceed the legal limits for many hours after the last drink. Activities that require fine motor skills, such as driving a motor vehicle, operating heavy equipment, may be affected for many hours after the last drink. Perceived "hangover" may in fact be due to the presence of high BAC! With CBAC, changing the type of drink i.e. regular beer (5%) to light beer (4%) and/or changing the pattern of drinking, i.e. slowly, or reducing the number of drinks, a significant effect on the BAC can be demonstrated. An 80 character cautionary statement can be inserted such that it appears in every screen where BAC values are displayed. All options that were selected while using the program can be printed, thus producing a customized report. 2. A teaching tool in an academic environment. CBAC can be used to show the different variables that can affect BAC. Age, sex, height and weight, as well as rates of metabolism to simulate the effects of various disease and drugs that induce enzyme activity can be infinitely varied and studied. Quantity of alcohol consumed and the duration of drinking can be varied for the same individual, demonstrate changes in BAC. Metabolic rate for individuals are difficult to predict. For simplicity, option to change metabolic rate has been included. In CBAC the default rate of elimination has been set as 15mg/100ml/hour (0.015 mg%). CBAC programme can be customized, such that this rate can be changed before every calculation is made. A different default rate can also be selected. Graphical display reflects the rate of metabolism and is shown at the top of the graphical display screen. Thus in a teaching environment the "what if" questions can be asked. What happens if the metabolic 760

3 rate of 15 mg/100ml/hr, commonly used in the forensic literature, increases or decreases. The elimination profile is presented in graphical format. Total body water, in liters, can also be displayed. Alcohol is consumed in many forms; beer, liquor and wine. All these have different alcohol concentration and the size (volume) of the beverage consumed varies. CBAC allows the user to input data in three different ways, i) generically: where a drink is defined as one beer (12 oz-5%) = 1.5 oz liquor (40%) = 5 oz wine (11.5%). ii) types of drinks of equal alcohol concentration grouped together and finally iii) in a user definable bar format. In this format the user creates a BAR MENU. Name, size (volume) and the concentration of the drink are defined while creating this menu. This option would be akin to going to the local bar and selecting drinks from the menu. CBAC displays the bar menu (Fig. 4). CBAC, in the background, calculates the quantity of alcohol in grams from the size (volume) and concentration of the alcoholic beverage consumed. Although driver of an automobile can be charged with "driving while impaired" at any BAC, BAC levels of^ 80mg/100 are associated with a criminal offence in Canada. In Canada there is also a provision in law, that if the BAC is between 50 and 80 mg/100 the driver can be temporarily suspended from driving his vehicle. In many States of the USA, BAC o f ^ 100 mg/100ml is associated with a the criminal offence and BAC of ^ 40 mg/100 is "illegal" for the DOT (department of transport) employees. CBAC allows the users to define "legal" driving limits. The options allow for two limits and can be customized to the local legislation. Given height, weight, sex, age, number and type of drinks, and over how many hours these were consumed, CBAC projects BAC. It then projects how many hours to wait for the BAC to fall below the previously defined legal driving limits (Fig. 5). In one of its options where the drinking period (e.g. a social evening) can be specified, CBAC can project how many drinks a person can have and how to pace these drinks to remain below the legal driving limit. We see applications of this program in various clinical and educational activities. Patient management in emergency departments, university departments of pharmacology (already in use at the University of Toronto), research in alcohol and alcoholism, alcohol treatment programmes, schools, drinking driver education, hostesses in private parties and restaurants and bars are but a few of these. REFERENCE [1] Watson P.E et. al., J. Ale Stud; 42, (1981) 761

4 John May 30, 1989, 10:09pm Weight: 73kg Sex: M Height: 180cm Which of the following would you like calculated, given the legal driving limit of 80mg/100ml? Calculate Blood Alcohol Calculator Maximum number of drinks in 1 hour Number of hours to wait after drinking Maximum number of drinks at a social event Number of drinks represented by BAC Next person Quit Fig. 1 John May 30, 1989, 10:17pm Weight: 73kg Sex: M Height: 180cm MAXIMUM NUMBER OF DRINKS AT A SOCIAL EVENT Maximum number of drinks you can take in 5.0 hours is 4.9. Space your drinks to 1.0 drinks per hour to remain under the limit of 50mg/100ml. OR Maximum number of drinks you can take in 5.0 hours is 6.1. Space your drinks to 1.2 drinks per hour to remain under the legal driving limit of 80mg/100ml. Your car keys can be taken away at a BAC between 50mg/100ml and 80mg/100ml (1 STANDARD DRINK=1 REGULAR BEER=1.5oz LIQUOR=5oz WINE) Fig

5 CD LO Blood Alcohol Concentration Comparison of Male and Female (Same height, weight and drinks) - CO W cr =3 0 1 T3 o 'v_ CD Q. 7 g > c CM H 763

6 John Weight: 73kg Fig. 4 ^Calculate BAC Regular Beer (12oz-5% Sex: White Wine Red Wine (7oz-11.5% (7oz-11.5% CALCULATE BLOOD ALCO Vodka Scotch Imp Beer (12oz-4.65% Kaluha (loz-33% Martini (2.50z-40% Use Bar menu Standard Drinks Mix Your Own Drinks Bailey Rum Gin (loz-17% Grand Marnier (loz-40% Lite Beer (12oz-4% Coffee drink (loz-40% Black Russian Liqueur (loz-40% Cream Chartreuse(loz-70% Brandy (loz-40% #Drinks- o o o o o o o o o o o o o o o o o o o Simulation Options-*---- Metabolic Rate Ask Metabolism No Output t Display TBW No Printer Higher Limit (mg/100ml) 80 Colours Lower Limit (mg/100ml) 50 Explodin Display Graph Yes Explode Extrapolate Back Yes Delay SI Units for Input No Simulati Concentration Units 80 mg/100ml Change B Warning message (Your drive Restore Quit Fig