Drink-driving in the general night-time driving population, Adelaide 1989

A roadside breath alcohol survey was conducted by the NHMRC Road Accident Research Unit in 1989 to monitor the efficacy of random breath testing (RBT) by the police. A reduction of 40 per cent in the proportion of drivers above the legal blood alcohol limit of 0.08 g/100 ml was found to coincide with a marked increase in the level of publicity of police RBT operations. Other factors may also have contributed to these large reductions in illegal drink-driving but this result was similar to that observed in 1987 when a major increase in publicity was accompanied by an increase in the level of enforcement of RBT. Although the full effect of these reductions has diminished with time, there appears to have been a decrease in illegal drink-driving in Adelaide from 1983 to 1987 and again to 1989.

Clinical pharmacokinetics in patients with liver disease

From considerations of hepatic physiology and pathology coupled with pharmacokinetic principles, it appears that altered drug elimination in liver disease may result from the following mechanisms: reduction in absolute cell mass, in cellular enzyme content and/or activity, in portal vein perfusion due to extrahepatic/intrahepatic shunting, or of portal perfusion of hepatocyte mass due to decreased portal flow or sinusoidal perfusion; increase in arterial perfusion relative to portal perfusion; preferential perfusion of the sinusoidal midzone and terminal zones by arterioles; potential for direct mixing of arterial blood within the space of Disse; reduced exchange across the endothelial lining; and impaired diffusion within the space of Disse. In general, oxidative drug metabolism is impaired in liver disease and the degree of impairment of oxidisation differs between drugs but correlates best with the degree of sinusoidal capillarisation, i.e. the degree of access of the drug from the sinusoid to the hepatocyte. Drug conjugation appears to be relatively unaffected by liver disease, whereas elimination by biliary excretion correlates best with the degree of intrahepatic shunting and not with sinusoidal capillarisation. As the latter should impair hepatocyte access of all compounds similarly, a potentially important mechanism could be impaired access of oxygen to hepatocytes as oxidative metabolism is much more sensitive to oxygen supply than are conjugation or biliary excretion. This suggests a potentially important therapeutic role for agents which increase the hepatic oxygen supply. Useful adjunctive strategies may also derive from the oxygen limitation hypothesis. Anaemia should be targeted as a critically important variable, as should oxygen-carrying capacity, i.e. modification of the smoking habit. Additionally, enzyme inducers such as barbiturates may be used if overriding hypoxic constraints are removed by oxygen supplementation. Agents likely to seriously compromise arterial perfusion of the hepatic vascular bed should be avoided, e.g. those causing postural hypotension or vasospasm. Vasodilators can be used to actively promote arterial perfusion. While the effect of liver disease on drug handling is highly variable and difficult to predict, there are well recognised principles for modifying dosage. These include halving the dose of drugs given systemically (or of low clearance drugs given orally) and a 50 to 90% reduction in the dose of drugs with a high hepatic clearance given orally. Changes in the pharmacodynamic effects of drugs (either alone or in addition to pharmacokinetic changes) can also be profound, and awareness of this possibility should be increased.

Measuring and modifying hospital drug use

OBJECTIVE

Various methods are available to quantitate medicinal drug use in hospitals. These represent a hierarchy of clinical specificity, complexity and cost of acquisition. Similarly, various strategies and methods are available to modify prescribing patterns. The objectives of this study are to illustrate these processes of measurement of drug use and modification of prescribing patterns using specific examples derived from practice at three major Australian teaching hospitals over 15 years.

DESIGN, SETTING, MAIN OUTCOME MEASURES

Methods to measure and modify drug usage in the three hospitals are outlined and 12 examples are presented by specific drug or drug category. Each example includes details of the methods used to detect inappropriate drug use (pharmacy purchases, pharmacy issues, prescription analysis, clinical record review, performance and outcome assessment), the intervention strategies used (re-educative, persuasive, facilitative, power), the methods employed to alter drug prescribing and the relative effectiveness and cost-efficiency of the interventions.

RESULTS

Readily available, relatively cheap quantitative methods provide significant information and an efficient basis for planning definitive studies, and substantial modification of prescription patterns is possible through the strategic use of limited manpower and resources.

Extradural haemorrhage in infancy and childhood. A review of 35 years' experience in South Australia

One hundred and two paediatric cases of extradural haemorrhage (EDH) were treated in Adelaide, South Australia, during the period 1954-1988; 10 were infants (0-2 years) and 92 were children (2-14 years). There were 9 deaths (mortality 8.8%). Long-term disabilities severe enough to interfere with school and/or employment were seen in 8 (7.8%) survivors. This relatively low number of adverse outcomes is partly an expression of a low incidence (5.9%) of associated intradural haematomas and few high-velocity impacts due to vehicular accidents. There is reason to believe that the results of treatment have improved in the decade 1977-1988. We attribute this in part to early diagnosis by computed tomography (CT), but a contributory factor may be earlier referrals from country centres to a paediatric trauma centre and rapid transfer, by air or road, by medical retrieval teams.

Publicity, police resources and the effectiveness of random breath testing

Random breath testing (RBT) of drivers by the police was introduced in South Australia in 1981 at a very low level of enforcement. As there was no lasting effect on illegal "drink driving" the resources devoted to RBT were increased in 1987. In the months after this change police doubled the number of drivers tested by RBT. Concurrent with this change in the level of enforcement of RBT was an extensive publicity campaign, which warned drinking drivers of their increased risk of detection by RBT units. A roadside breath alcohol survey, conducted in metropolitan Adelaide late at night to evaluate the effect of these changes, showed a 34% reduction in the proportion of car drivers detected with a blood alcohol concentration at or above the legal limit of 0.08 g/100 mL.

Design and trial of a metronidazole loading dose regimen for patients undergoing emergency surgery

A dosing regimen for administration of metronidazole to patients undergoing emergency surgery was designed using pharmacokinetic data. Computer estimates of the pharmacokinetic parameters from normal volunteers were used to determine a loading dose protocol that would achieve plasma metronidazole levels above 6.2 micrograms/mL, that is, above the minimum inhibitory concentration (MIC) of most pathogenic anaerobic bacteria, at the time of surgery. The protocol aimed to identify the minimum intravenous metronidazole dose in combination with a rectal suppository regimen. This was calculated to be a 1 g (two 500 mg) metronidazole rectal suppository dose administered when the decision to operate was made, followed by a 200 mg intravenous dose at the induction of anaesthesia if the time to surgery was within 1-8 h. This protocol was tested in 10 patients undergoing emergency abdominal/pelvic surgery. All patients in the trial were found to have levels well above the MIC at the time of surgery (mean = 17.06 micrograms/mL, s.d. = 4.76). It is concluded that appropriate use of metronidazole suppositories can minimize intravenous dosage requirements for metronidazole under conditions of emergency loading as well as elective surgery.

Pontomedullary tears and other gross brainstem injuries after vehicular accidents

In a series of 988 autopsied victims of road crashes, there were 36 (3.6%) cases of gross primary brainstem injury. These fell into three groups. The first comprised eight cases of pontomedullary tearing without other gross brain injury: in seven of these, there were associated atlanto-occipital dislocations and/or high cervical fracture-dislocations. The usual cause appeared to be facial impact inducing acute hyperextension. Second, there were 17 cases of pontomedullary tearing associated with other brainstem lacerations and/or major damage elsewhere in the brain: in all, there were fractures of the skull base, typically transverse middle fossa fractures. Most of these injuries appeared to be due to facial impacts transmitting force to the anterior skull base, although hyperextension was also a factor in some. There was a third heterogeneous group of 11 cases with brainstem lacerations in sites other than the pontomedullary junction: in some of these it appeared that the impacts had caused skull base fractures by inducing calvarial torsion. In this series, the proportion of motorcyclists (41.7%) was double the expected figure. The use of a helmet modifies the mechanisms of impact head injury; the overall benefits of helmet use are well established, but there is need for more research on helmet design.

Replica casting of the skull base

A new technique is described of obtaining a replica cast of the human skull base by making an epoxy resin case from a silicone rubber mould of the skull base. The replica provides an accurate and permanent record of the shape and dimensions of the base of the cranial cavity, together with the location and extent of any fractures of the skull. The method gives a good correlation between these characteristics and the type and extent of brain damage.

Non-fatal injuries among motorcyclists treated as in-patients in a general hospital

In a study of the injury pattern among 198 motorcyclists who sustained road traffic accidents from 1986-1987, it was found that the following body regions, in decreasing order of frequency, were involved: external region (surface or integumentary lesion of any body region) with 285 injuries, extremities and bony pelvis with 118 injuries, head and face with 94 injuries, chest with 10 injuries, abdomen with 3 injuries, and spine with 2 injuries. Despite the extensive use of crash helmets, head injuries were still a common and severe form of injury resulting from traffic accidents, indicating the need for improvement of safety standards of crash helmets. Lower limb injuries, mostly fractures of bones and dislocation of joints, are also amenable to prevention through design of leg protection devices. Injuries to other body regions are difficult to prevent and other measures such as legal and administrative means, should be fully exploited in accident prevention.

Prospective audit of aminoglycoside usage in a general hospital with assessments of clinical processes and adverse clinical outcomes

A comprehensive, multiphasic review of gentamicin and tobramycin utilization was undertaken with audits of the microbiological sensitivity of Gram-negative pathogens; indications for the prescription of aminoglycoside agents; the utilization of assay services; the adequacy of clinical drug delivery by measures of serum antibiotic levels; and the assessment of adverse outcomes by markers of nephrotoxicity. The great majority of clinical isolates of target organisms (n = 4208) was more sensitive to gentamicin (96%) and to tobramycin (99%) than to all alternative agents, including first- and third-generation cephalosporin agents. A review of the indications for the prescription of aminoglycoside agents by clinical criteria showed that in 85.6% of 278 documented cases, the choice of agent was appropriate by clinical and microbiological criteria. In a substantial (77.6%) proportion of the 511 patients who were receiving therapeutic courses of an aminoglycoside agent, serum drug assays had been performed. Assay data could not be interpreted adequately in 52.6% of 3079 assayed cases as a result of inadequate data on administration regimens (39.7%) or sampling regimens (12.9%). Where sampling was documented adequately, there was extreme variation (zero to five hours) in post-dose sampling. In only 33.2% of cases could it be concluded unambiguously that the patients were receiving safer, adequate therapy for clinically significant infections, 5.6% of patients were receiving potentially toxic doses, and 8.6% of patients showed suboptimal concentration profiles. The majority of potentially toxic levels were associated with adverse effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative pharmacokinetics of enalapril and lisinopril, alone and with hydralazine

A single-dose, single-blind, crossover study of vasodilator/angiotensin-converting enzyme (ACE) inhibitor interactions was carried out in 16 volunteers. Enalapril 20 mg and lisinopril 20 mg were administered either alone or in combination with hydralazine 25 mg. Co-administration of hydralazine significantly increased the area under the plasma concentration time curve (AUC) of lisinopril (AUC0-48 h 766.8 +/- 66.3 ng.h/ml (lisinopril) vs 1022.3 +/- 115.3 ng.h/ml (lisinopril + hydralazine)). This did not occur with enalaprilat (AUC 710.1 +/- 51.2 ng.h/ml (enalapril) vs 681.9 +/- 44.9 ng.h/ml (enalapril + hydralazine); mean +/- SEM). Urinary recovery of lisinopril showed a similar trend, but group differences did not achieve statistical significance despite comparable confidence intervals. Although hydralazine had no effect on the bioavailability of enalapril, significantly increased bioavailability was observed with lisinopril. This type of drug interaction is rare. The underlying mechanism is unclear, but may relate to increased absorption of lisinopril.

Triplet state characteristics and singlet oxygen generation properties of anthracyclines

The triplet states of adriamycin (Ad), daunomycin (D) and two daunomycin analogues, daunomycinone (Dc) and daunomycin N-trifluoroacetamide (DAc), have been studied using laser flash photolysis and pulse radiolysis techniques. Triplet lifetimes, molar absorption coefficients, energy levels and quantum yields have been obtained for Dc and DAc, and estimated for D and Ad. Time-resolved near-infrared singlet oxygen luminescence measurements have been carried out on D, Ad and 5-iminodaunomycin (5-ID) in 2H2O solution and Dc in benzene solution at room temperature. Singlet oxygen quenching by the water-soluble anthracyclines was observed and a second-order rate constant of approx. 10(8) M-1.s-1 obtained. Electron spin resonance experiments have demonstrated that D photoexcited at lambda less than or 365 nm gives rise to singlet oxygen as shown by its reaction with 2,2,6,6-tetramethyl-4-piperidone to give the corresponding nitroxyl radical. Although all the anthracyclines studied have the ability to photosensitize the formation of singlet oxygen, the quantum yields are very low (phi delta approximately 0.02-0.03), suggesting that these anthracyclines would be poor photodynamic sensitisers.

Cervical spine injuries in road traffic crashes in South Australia, 1981-86

The records of all cases of injury to the cervical spine sustained in road crashes for the 6 year period (1 January 1981 to 31 December 1986) which were admitted to the Spinal Injuries Unit of the Royal Adelaide Hospital, to the Adelaide Children's Hospital, or were identified at post-mortem examination were examined, and the relevant data extracted. There were 291 cases in the non-fatal group, and 161 in the fatal group. These represent a complete enumeration of all such patients in the state of South Australia over the 6 year period, given that up to 50% of cervical injuries in fatal cases can be missed. Comparison of the two groups showed that the fatal group had a much higher proportion of pedestrians, and persons over 50 years of age. About one-half of the fatal group had injuries at the level of C1 or the atlanto-occipital articulation. The most frequent level of injury in the non-fatal group was C2 (29.2%). About 30% of the non-fatal cases had some spinal cord damage. Case fatality rates were calculated, and ranged from 100% for injury at the atlanto-occipital articulation to 8% at C2. The fatality rate of pedestrians was about 4 times higher than that of vehicle occupants. About three-quarters of all cervical spine injuries occurred in vehicle occupants. There was an increase in the number of cases occurring in each year of the period studied. This rise was noted in non-fatal cases, in males, in vehicle occupants, and in crashes in the country.

Absorption and elimination of bismuth from oral doses of tripotassium dicitrato bismuthate

The pharmacokinetics of bismuth subcitrate were studied in plasma and urine under conditions of single and multiple dosing (28-56 days) using atomic absorption technique. Single dose plasma pharmacokinetics showed peak concentrations of 5.5-57.5 micrograms.l-1 (mean = 24.7 micrograms.l-1), reached between 30 and 60 min post dosing with an apparent biphasic elimination pattern. Multiple dose studies showed a continuing rise in plasma concentration and urine excretion rate reaching apparent steady-state levels over 7-29 days (mean = 18 days). Washout studies in 6 individuals reciprocated accumulation. Maximum equilibrated plasma levels of 7.6-58.3 micrograms.l-1 (mean = 38.3 micrograms.l-1) were well below those associated with encephalopathy. The half-life of bismuth elimination was 20.7 days. Present patterns of intermittent dosing with bismuth are unlikely to be associated with bismuth accumulation despite slow accumulation and elimination.

Trends in Australian mortality of asthma, 1979-1985

Trends in Australian mortality rates that have been ascribed to asthma and to non-tuberculous, non-malignant respiratory diseases were examined for the period 1979-1985. Mortality rates of asthma and respiratory diseases increased substantially from 1979 to 1985, and in the case of asthma, the crude death rate in 1985 was higher than at the peak of the "epidemic" of the 1960s. The increase in mortality of asthma was most pronounced in those of greater than 60 years of age (from 11.5 per 100,000 such population in 1979 to 22.9 per 100,000 such population in 1985). Asthma mortality rates in five- to 34-year-old persons increased, although there were marked yearly fluctuations, and deaths of asthma in this age-group comprised only a small percentage (13% in 1985) of all deaths of asthma. Reasons that are considered for the rising death rate of asthma include changes in diagnostic fashion; an increase in the incidence or a change in the natural history of asthma; and an increased case fatality rate. With the presently-available data, it is not possible to distinguish among these possible explanations.

Extradural haemorrhage: strategies for management in remote places

A study of 109 cases of extradural haemorrhage (EDH) treated in South Australia over a period of 7 years showed that 35 cases (32.1 per cent) presented in country areas at considerable distances from a neurosurgical service: the mortality in these country cases was 22.9 per cent, comparing unfavourably with a mortality of 12.2 per cent in metropolitan cases. The country series contained a disproportionately large number of cases with multiple intracranial haemorrhages, which are known to have a poorer outcome; when these cases were excluded, the rural mortality (12.5 per cent) was only a little over the metropolitan mortality (9.7 per cent). These data suggest that it is possible to manage extradural haemorrhages successfully even in places remote from a neurosurgical centre, if communications and air transport are used effectively. However, it was found that emergency operations carried out in country hospitals were sometimes inadequate or done too late. Medical retrieval teams based on city hospitals were sent out on 15 occasions, either to assist a general surgeon to complete an emergency operation, or to provide intensive care during transfer to a neurosurgical unit. Osmotherapy (mannitol and/or frusemide) has been useful in gaining time for transfer; the choice between immediate operation and transfer may be difficult, and decisions should take transfer time, clinical state and rate of deterioration into account.

Renal sodium retention in cirrhosis: tubular site and relation to hepatic dysfunction

Renal sodium handling, assessed by the response to acute saline loading, was investigated in 14 well-compensated, nonascitic alcoholic cirrhotics and six normal controls. Urinary sodium excretion in cirrhotic patients (199 +/- 141 mumoles per min) was significantly lower than in controls (387 +/- 104 mumoles per min; p less than 0.01) at 3 hr postinfusion. In contrast to controls, renal plasma flow and glomerular filtration rate did not increase in the cirrhotics in response to acute saline loading. Proximal fractional reabsorption of sodium was estimated by clearance techniques in the presence of a hypotonic diuresis. Cirrhotic subjects with impaired functional liver cell mass as assessed by antipyrine clearance were unable to decrease proximal fractional reabsorption of sodium significantly in response to saline loading. Assessment in the cirrhotics included measurement of hepatic vein pressure gradient, indocyanine green extraction ratio, indocyanine green clearance, and antipyrine clearance as indices of portal pressure, intrahepatic shunting, hepatic blood flow and functional hepatocellular mass, respectively. Urinary sodium excretion in the cirrhotics correlated strongly with antipyrine clearance (r = 0.839, p less than 0.0001) and weakly with portal pressure (r = 0.562, p = 0.037). No correlation was seen with the other indices of hepatic blood flow and shunting. The findings of this study suggest that alcoholic cirrhosis is associated with a decline in hepatocellular function which results in either a decreased clearance of a salt-retaining hormone or decreased synthesis of a natriuretic hormone.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of haematoporphyrin derivative and haematoporphyrin excited states in cell environments

The photosensitiser currently used in the photodynamic therapy of cancer is haematoporphyrin derivative. Pulsed laser studies of this material and also of the "parent" molecule haematoporphyrin in polyoma-transformed fibroblast cells have now been studied. We report, for the first time, the observation of the triplet absorption of these sensitisers in cells. The corresponding triplet-triplet spectra are red shifted compared to aqueous buffer, lambda(max) 420 nm shifts to 460 nm. We also report our failure to observe singlet oxygen from the cells even though the triplet state can be seen to interact with the oxygen and even though singlet oxygen can be readily detected with the same sensitisers bound to serum albumin.

Improved assay for bismuth in biological samples by atomic absorption spectrophotometry with hydride generation

This simple, rapid, sensitive, reliable, and economical assay for bismuth in plasma, erythrocytes, and urine is based on atomic absorption spectrophotometry with hydride generation. Acid digestion eliminates the problem of foaming, which hitherto has complicated such assay of bismuth in plasma and erythrocytes. The detection limit of the assay has been improved to 0.1 micrograms/L, as compared with a previously documented limit of 2.5 micrograms/L. Average recovery exceeded 95% in all biological fluids. Economy of use derives from elimination of need for electrodeless discharge lamps and atomic absorption grade borohydride. Determination of basal concentrations of bismuth in clinical samples of body fluids gave reference intervals of 0.1-3.5 micrograms/L for plasma, 0.3-4.6 micrograms/L for urine.