Trends in childhood body mass index between 1936 and 2011 showed that underweight remained more common than obesity among 398 970 Danish school children.

AIM: To examine trends in all body mass index (BMI) groups in children from 1936 to 2011. METHODS: We included 197 694 girls and 201 276 boys from the Copenhagen School Health Records Register, born between 1930 and 1996, with longitudinal weight and height measurements (6-14 years). Using International Obesity Task Force criteria, BMI was classified as underweight, normal-weight, overweight and obesity. Sex- and age-specific prevalences were calculated. RESULTS: From the 1930s, the prevalence of underweight was stable until a small increase occurred from 1950 to 1970s, and thereafter it declined into the early 2000s. Using 7-year-olds as an example, underweight changed from 10% to 7% in girls and from 9% to 6% in boys during the study period. The prevalence of overweight plateaued from 1950 to 1970s and then steeply increased from 1970s onwards and in 1990-2000s 15% girls and 11% boys at 7 years had overweight. The prevalence of obesity particularly increased from 1980s onwards and in 1990-2000s 5% girls and 4% boys at 7 years had obesity. These trends slightly differed by age. CONCLUSION: Among Danish schoolchildren, the prevalence of underweight was greater than overweight until the 1980s and greater than obesity throughout the period. Thus, monitoring the prevalence of childhood underweight remains an important public health issue.

Immediate hemodynamic consequences of MAST inflation in normo- and hypovolemic anesthetized swine.

Use of the military antishock trouser (MAST) remains controversial in part because its mechanism(s) of action are poorly understood. We studied two aspects of the hemodynamic response to MAST inflation in 14 anesthetized swine. First, in six swine the relation that existed between inferior vena cava flow and aortic pressure/cardiac output was determined before and during inflation of the MAST, and then before and after removal of 30% of the calculated blood volume. Inflation of the MAST before hemorrhage had little effect on cardiac output but increased aortic pressure by 25%. Inflation of the MAST after hemorrhage increased cardiac output by 41% and increased aortic pressure by 62%. Three different inflation pressures were studied (40, 80, and 120 mm Hg) and were found to give equivalent results. Inflation of the MAST translocated about 3 ml/kg of blood to the heart. A second group of eight swine were instrumented so that the radiomicrosphere technique could be used to measure organ blood flow. Inflation of the MAST following hemorrhage increased coronary perfusion by 50% and cerebral perfusion by about one third. Flow to kidney, liver, and small intestine was not changed. We conclude that, in addition to tamponade of venous bleeding and the splinting of lower extremity fractures, use of the MAST might cause a clinically important increase in the perfusion of the heart and brain in some trauma patients.

Coronary blood flow during cardiopulmonary resuscitation in swine.

Recent papers have raised doubt as to the magnitude of coronary blood flow during closed-chest cardiopulmonary resuscitation. We will describe experiments that concern the methods of coronary flow measurement during cardiopulmonary resuscitation. Nine anesthetized swine were instrumented to allow simultaneous measurements of coronary blood flow by both electromagnetic cuff flow probes and by the radiomicrosphere technique. Cardiac arrest was caused by electrical fibrillation and closed-chest massage was performed by a Thumper (Dixie Medical Inc., Houston). The chest was compressed transversely at a rate of 66 strokes/min. Compression occupied one-half of the massage cycle. Three different Thumper piston strokes were studied: 1.5, 2, and 2.5 inches. Mean aortic pressure and total systemic blood flow measured by the radiomicrosphere technique increased as Thumper piston stroke was lengthened (mean +/- SD): 1.5 inch stroke, 23 +/- 4 mm Hg, 525 +/- 195 ml/min; 2 inch stroke, 33 +/- 5 mm Hg, 692 +/- 202 ml/min; 2.5 inch stroke, 40 +/- 6 mm Hg, 817 +/- 321 ml/min. Both methods of coronary flow measurement (electromagnetic [EMF] and radiomicrosphere [RMS]) gave similar results in technically successful preparations (data expressed as percent prearrest flow mean +/- 1 SD): 1.5 inch stroke, EMF 12 +/- 5%, RMS 16 +/- 5%; 2 inch stroke, EMF 30 +/- 6%, RMS 26 +/- 11%; 2.5 inch stroke, EMF 50 +/- 12%, RMS 40 +/- 20%. The phasic coronary flow signal during closed-chest compression indicated that all perfusion occurred during the relaxation phase of the massage cycle. We concluded that coronary blood flow is demonstrable during closed-chest massage, but that the magnitude is unlikely to be more than a fraction of normal.

Organ blood flow and the cause of death following massive hemorrhage.

We tested the hypothesis that death occurring shortly after massive hemorrhage can be attributed to the development of positive feedback loops arising from deficient blood flow to one or more vital organs such as the heart, brain, and respiratory muscles. The radiomicrosphere technique was used to measure organ blood flow in unmedicated, chronically instrumented swine subjected to removal of 41 ml/kg of blood in 15 min. Ten swine survived the experiments and five died, all within 2 hr after completion of hemorrhage. Cardiac output but not blood pressure was lower in nonsurvivors (mean +/- 1 SD). No difference was found in regard to blood flows to the heart, brain, and diaphragm (flow in ml/gm/min) between survivors and nonsurvivors. Although blood flow posthemorrhage to kidney, organs of the splanchnic bed, and the carcass tended to be greater in survivors compared to nonsurvivors, the difference reached statistical significance only in the small intestine. We conclude that in this model there is no evidence that death following massive hemorrhage results from positive feedback loops arising from deficient perfusion of the coronary or cerebral circulation. It is more likely that death results from abnormalities arising in the carcass and/or splanchnic bed.