The effect of associated injuries, blood loss, and oxygen debt on death and disability in blunt traumatic brain injury: the need for early physiologic predictors of severity

Studies of 4590 patients with blunt trauma injuries admitted to a Level I Trauma Center, have shown that 37% had a blunt traumatic brain injury (BTBI). Of these brain injured patients 60% has an associated other injury. Examination of mortality has shown that those with an isolated brain injury had an 11% mortality compared with 21.8% in those with an associated systemic injury. Further investigation demonstrated that the cause of the increased mortality was related to the blood loss associated with the injuries and that when hypovolemic shock resulted, mortality rose from 12.8 to 62%. The severity of the associated injuries effect on the brain injured patient could be estimated by a parameter of oxygen debt, the base deficit and this allowed for a quantitative estimate of the probability of death as an index of severity. A combined linear logistic model using the admission Glasgow Coma Score (GCS) as a measure of brain injury and the base deficit as a measure of physiologic injury provides such a predictive score. The effect of associated injuries in patients with moderate brain injury (AIS 2,3) was to increase the average total cost of medical care in the first year of injury by three-fold ($12,489 to $36,177) and for severe brain injury (AIS 4,5) to increase average cost from $59,000 in isolated BTBI to $90,000 in BTBI with associated injury. The high incidence of brain injuries in motor vehicle crashes (MVC) caused by lateral impacts and their association with other side-impact injuries (lungs, spleen, kidney, and pelvic fractures) in which large blood volume losses are common, focuses attention on the need for side impact protection standards that simultaneously protect brain, thoracoabdominal viscera, and pelvis as a means of reducing the severity and cost of lateral impact MVCs.     

Associations of serum and dietary magnesium with cardiovascular disease, hypertension, diabetes, insulin, and carotid arterial wall thickness: the ARIC study. Atherosclerosis Risk in Communities Study

The objective of this study was to examine the relationships of serum and dietary magnesium (Mg) with prevalent cardiovascular disease (CVD), hypertension, diabetes mellitus, fasting insulin, and average carotid intimal-medial wall thickness measured by B-mode ultrasound. A cross-sectional design was used. The setting was the Atherosclerosis Risk in Communities (ARIC) Study in four US communities. A total of 15,248 participants took part, male and female, black and white, aged 45-64 years. Fasting serum Mg, lipids, fasting glucose and insulin were measured; as was usual dietary intake by food frequency questionnaire and carotid intima-media thickness by standardized B-mode ultrasound methods. The results showed that serum Mg levels and dietary Mg intake were both lower in blacks than whites. Mean serum Mg levels were significantly lower in participants with prevalent CVD, hypertension, and diabetes than in those free of these diseases. In participants without CVD, serum Mg levels were also inversely associated with fasting serum insulin, glucose, systolic blood pressure and smoking. Dietary Mg intake was inversely associated with fasting serum insulin, plasma high density lipoprotein-cholesterol, systolic and diastolic blood pressure. Adjusted for age, race, body mass index, smoking, hypertension, Low density lipoprotein-cholesterol, and field center, mean carotid wall thickness increased in women by 0.0118 mm (p = 0.006) in diuretic users and 0.0048 mm (p = 0.017) in nonusers for each 0.1 mmol/l decrease in serum Mg level; the multivariate association in men was not significant. In conclusion, low serum and dietary Mg may be related to the etiologies of CVD, hypertension, diabetes, and atherosclerosis.     

Choice of anaesthetic regimen influences haemodynamic response to cemented arthroplasty

Haemodynamic changes during bilateral cemented arthroplasty (BCA) were compared in dogs anaesthetized with isoflurane/N2O (ISOF) or diazepam/fentanyl (100 microg x kg(-1))N2O(FENT). Eight animals were anaesthetized with each regimen. After establishing monitoring and recording baseline values, BCA was performed. Haemodynamic measurements included aortic blood pressure (ABP), pulmonary artery pressure (PAP), right and left atrial pressures, and cardiac output. These were recorded at 30, 60, 180 and 300 sec after BCA. Lungs were removed and examined postmortem using quantitative morphometry. Groups demonstrated similar increases in PAP (ISOF 15 +/- 2 to 32 +/- 7, FENT 19 +/- 4 to 38 +/- 13; P> 0.05 between groups, P< 0.05 vs baseline). The proportion of lung vasculature occluded by fat was not different between groups (ISOF 9.63 +/- 3.38%, FENT 8.85 +/- 2.20%). Stroke volume decreased similarly in both groups (P> 0,05 between groups, P< 0.05 vs baseline). However, ABP decreased within one minute of BCA in ISOF (111 +/- 17 to 55 +/- mmHg, P< 0.05 and two of eight dogs died. All FENT dogs survived and hypotension (118 +/- 20 to 102 +/- 24 mmHg) was transient and less severe (P< 0.05 vs ISOF). Increased heart rate (HR) was noted in FENT following BCA (73 +/- 8 to 108 +/- 25 beats x min(-1); P< 0.05). Baseline HR was higher in ISOF (P< 0.05) and no increase in HR was noted. Systemic vascular resistance decreased in ISOF (P< 0.05), but not FENT (P> 0.05 vs baseline, P< 0.05 vs ISOF). To assess the role of slower baseline HR in FENT (73 +/-8) versus ISOF (131 +/- 5), six FENT dogs were paced (130 beats x min(-1)) with epicardial leads and an AV sequential pulse generator to simulate the ISOF group's baseline HR. Haemodynamic stability was maintained in this group in spite of a more rapid baseline HR. The choice of anaesthetic regimen strongly influenced acute haemodynamic changes in response to BCA.