Alcohol Flashcards
What is alcohol
OH group attached to carbon chain
Ethanol in alcoholic drinks
Spectrum of alcohol use
Teetotal = 10% Sensible/social drinker - 14units/week Heavy drinker - men > 7 , women > 5 units/day Problem drinker - continues drinking whilst having problems in their life Dependent drinker - > 8-10 units/day
Levels of alcohol drunk
Sensible < 14 units/week
Hazardous > 14 units/week
Dangerous > 35 u/w
Cost equation of alcohol in society
Debit - £2bn - absenteeism - unemployment - offences - RTA - health - premature death Credit - £7bn - excise duty - exports - jobs
Alcohol as a factor in social harm
20% of RTAs 25% of drownings 30% of accidents 35% of divorces and child abuse 40% of domestic violence 50% of murders 60% of head injuries 70% of suicides 80% of fire deaths
Features of alcohol dependence
Aware of compulsion to drink Prominent drink seeking behaviour Tolerance to its effects Withdrawal syndromes on stopping Avoidance of withdrawal Social psychological and physical problems Criteria - heavy drinking - > 10u/d - tolerance - withdrawal syndromes - inability to stop drinking - abnormal blood tests - GGT, CDT, MCV
Average content of alcoholic beverages
Alcohol content expressed as % alcohol by volume
- 4% = 4ml/100ml beer
1ml alcohol weight 0.79g
Amount alcohol (ml) = volume consumed (ml) x % ABV
1 unit = 10ml or 8g or pure alcohol
1unit =
- half pint of weak beer (3.5%)
- small (<100ml) glass wine (12%)
- small (28ml) measure of sprits (40%)
1 unit = amount of alcohol (ml) x 0.79 / 10
Factors affecting absorption of alcohol
Gastric emptying accelerated - increased absorption
- tolerance
- gastrectomy
Gastric emptying slowed - reduced absorption
- food in stomach
- drugs
Absorption of alcohol
20% from stomach
80% from small intestine
Rate of alcohol absorption depends on rate of gastric emptying
Food reduced rate and extent of absorption - 2/3 fasting value
Depends on type of drink - strength, effect of congeners
- 10-20% optimal
- champagne absorbed quick - high conc and bubbled
- beer absorbed slow - low conc, congeners
- neat spirits irritate stomach - mucus delays absorption
Absorption complete within 1-3 hours
Kinetics of alcohol
Absorption phase
Distribution phase
- peak = Cmax ( max concentration)
- 15mg/100mls from 1 unit on empty stomach
Elimination phase
- mostly by liver
Tmax = time at max concentration
C0 = hypothetical track back of max concentration if all absorbed instantly
= weight alcohol consumed x 100 / body weight x widmap factor
W.F = measure of body water
= 0.6 roughly
Rate of elimination
= 10-20mg alcohol / 100ml blood / hour
About 1 unit per hour
Calculate blood alcohol levels
C at T hours = C0 - (rate of elimination x number of hours)
Breath alcohol
1-2 hours after drinking
BAC:BrAC = 2300:1
Vitreous humour alcohol concentration
During absorption BAC > VHAC At equilibrium BAC < VHAC (ration 0.8) - due to higher water concentration in VH - takes longer to get into VH Cannot reliably predict BAC from VHAC VHAC corroborates BAC conc
Urine blood alcohol concentration
Urine collects in bladder over several hours
- UAC average of several hours of excretion
- UAC < BAC during absorption phase
- UAC > BAC during elimination phase
Distribution of alcohol
Dissolves in water
Distributed by bloodstream
Taken up by tissues in proportion to water content
- more alcohol removed from blood into water rich bone and muscle
- less alcohol removed from blood by fatty tissue
- those more lean able to take up more alcohol for lower BAC
Factors affecting blood alcohol concentration
Depends on - how much alcohol consumed - volume of distribution = mass consumed / volume of distribution Lean body mass = Wt x WF
What is Widmark Factor
Gives rough estimate of BAC after alcohol - assumes instantaneous 100% absorption
Factor is proportion of body water
- 0.68 for M and 0.55 for F
- calculate from online chart
Calculate BAC (Co)
Weight alcohol consumed (g) x 100
/
Body weight (g) x W.F
C at T hours = C0 - ( elimination rate x T)
Conversion factors for body fluids
BrAC = BAC / 2.3 UAC = BAC / 0.75 VHAC = BAC /0.8
Legal limit for driving
35 (E) or 22(S) micrograms alcohol / 100ml breath
80 (E) or 50 (S) mg alcohol/ 100ml blood
Elimination of alcohol
90% broken down in liver Small amounts lost in - breath - 2-5% - sweat - 2-5% - urine - 2-5% Rate of elimination (b) is 10-20mg per 100ml blood per hour - average 15 mg/100ml/h = 1 unit/ hour - up to 40 in alcoholics Amount eliminated in T hours = (b x T)
Alcohol metabolism
Ethanol -> acetaldehyde - by alcohol dehydrogenase Acetaldehyde -> acetate - by aldehyde dehydrogenase Releases CO2 and H2O Forms uric acid, ketones and triglycerides
Stages of intoxication
Excitement - BAC < 100mg%
- depression of higher inhibitory cortical function
Confusion - BAC 100-200mg%
- depression of limbic system - memory, orientation
- depression of cerebellum - coordination, speech
Stupor - BAC > 200mg
- depression of upper BS - RAS - conscious level
- depression of lower BS - breathing and vasomotive centres
Acute intoxication may mimic
Head injury Neurological disease Diabetic hypoglycaemia Epilepsy and related states Drug intoxication
Features of hangover
Toxic effects of alcohol metabolites and congeners on brain and GIT
Headache, malaise, nausea, tremor
Temporary and self-limiting
Dehydration and hypoglycaemia worsen
Effect on alcohol on performance
Decreased muscular control and coordination Increased reaction times Impaired peripheral vision Inability to judge speed and distance Inability to deal with unexpected Falsely increased confidence
Features of alcohol dependence
Aware of compulsion to drink Prominent drink seeking behaviour Tolerance to its effects Withdrawal syndromes on stopping Avoidance of withdrawal Social, psychological and physical problems
Factors leading to alcoholism
Constitution - low self-esteem - habit - boredom - loneliness - anxiety and depression - ethnicity Environment - availability - peer pressure - occupation - stress - competitive lifestyle - unemployment
Features of alcohol withdrawal
Uncomplicated
- onset 6-12 hours
- peak 48 hours
- lasts few days
- features tremor, N+V, malaise, headache, insomnia, weakness, sweating, tachycardia, hypertension, anxiety, depression, irritability, transient hallucinations
Causes of death in alcoholics
Acute alcohol intoxication
Trauma
Alcohol related disease
Incidental natural disease
Physical complications of alcohol
GIT - oesophagitis - Mallory-Weiss tears - gastritis - duodenitis - peptic ulcer - malabsorption - diarrhoea - pancreatitis Liver - fatty change - alcoholic hepatitis - cirrhosis - liver failure - portal hypertension and oesophageal varices - liver cancer CVS - arrhythmias - sudden death - alcoholic cardiomyopathy - hypertension CNS - Wernicke's encephalopathy - Korsakoff's syndrome - cerebellar degeneration - cerebellar atrophy - alcoholic dementia - alcoholic hallucinosis - peripheral neuropathy Nutrition - early obesity - later malnutrition - vitamin deficiencies Metabolic - hypoglycaemia - hyperlipidaemia - hyperuricaemia - lactic acidosis
Fatal alcohol intoxication
Fatal level variable > 250mg% in non-tolerant person > 450 mg% in tolerant Urinary alcohol conc > BAC if death follows prolonged coma Mechanisms - brain stem depression - positional asphyxia - inhalation of vomit
Features of post-mortem alcohol resdistribution
Passive diffusion of unabsorbed alcohol from
- stomach
- aspirated vomit in airways
To central vessels
< 400% difference between central vessels and peripheral vein
