Mechanical ventilation withdrawal
[black small square] When critically ill patients are receiving mechanical ventilation, physicians may decide to withdraw it in anticipation of death. At times, the reasons for the decision may not be clear. Experts aimed to study the clinical determinants associated with such a withdrawal. Researchers studied 851 adult patients receiving mechanical ventilation in 15 intensive care units. Of this sample, 63.3% were successfully weaned from mechanical ventilation, 19.5% had it withdrawn, and 17.2% died while receiving mechanical ventilation. The experts recorded patients' physiological data, daily multiple organ dysfunction scores, decision-making ability, type of life support, existence of a do-not-resuscitate order, physician's prediction of patient status, and physician's perception of patient's life support preferences.
The researchers concluded that age, illness severity, and organ dysfunction are not the strongest determinants of mechanical ventilation withdrawal. Rather, the physician's perception that the patient doesn't want life support, the physician's prediction of a low probability of survival if placed in the ICU, and a high likelihood of poor cognitive function, in addition to inotrope or vasopressor use, determine ventilation withdrawal.
Source: Cook, D., et al.: "Withdrawal of Mechanical Ventilation in Anticipation of Death in the Intensive Care Unit," The New England Journal of Medicine. 349 ( 12 ): 1123-1132, 2003.
Pyridostigmine bromide may reduce ventricular arrhythmia density
[black small square] Experts are aware that increased ventricular arrhythmia density and reduced heart rate variability are linked to risk of death in heart failure patients. A study set out to determine whether short-term administration of pyridostigmine bromide, a cholinesterase inhibitor that increases heart rate variability in normal subjects, reduces ventricular arrhythmia density and increases heart rate variability in heart failure patients. The patient sample received either pyridostigmine or placebo. After having their arrhythmias analyzed via electrocardiogram, patients were split into two groups according to their ventricular arrhythmia density.
For the arrhythmia sample, the administration of pyridostigmine resulted in a 65% reduction of ventricular ectopic activity. For the heart rate variability sample, pyridostigmine increased mean R-R interval. Researchers concluded that pyridostigmine reduces ventricular arrhythmia density and increases heart rate variability in patients with heart failure, probably because of its cholinomimetic effect. They noted, however, that further research is needed, specifically, in long-term trials.
Source: Behling, A., et al.: "Cholinergic Stimulation with Pyridostigmine Reduces Ventricular Arrhythmia and Enhances Heart Rate Variability in Heart Failure," American Heart Journal. 146 ( 3 ): 494-500, 2003.
Projecting stroke deaths
[black small square] Experts believe that age adjustment of stroke mortality rates obscures the impact of population changes on the total burden of disease. They hold that ischemic stroke deaths may climb unless future declines in stroke death rates offset the projected growth in high-risk populations. Researchers used ischemic stroke mortality data for 1979 to 1998 to create a model to predict stroke death rate changes as a function of time for 42 groups categorized by age, sex, and race. They then used population projections to calculate the expected number of ischemic stroke deaths in the United States for the next 30 years on the basis of age, sex, and race.
The total predicted number of stroke deaths grew by 98% from 2002 to 2032, while the total projected increase in the U.S. population grew by only 27%. These findings indicate that if recent trends in ischemic stroke mortality continue, U.S. stroke deaths will double over the next 30 years.
Source: Elkins, J., Johnston, C.: "Thirty-Year Projections for Deaths from Ischemic Stroke in the United States," Stroke. 34 ( 9 ): 2109-2112, 2003.
Hepatitis B and C transmission
[black small square] The Centers for Disease Control and Prevention (CDC) released a report about the transmission of hepatitis B virus (HBV) and hepatitis C virus (HCV) in outpatient health care settings. HCV was transmitted to noninfected patients in a private physician's office in New York City; HBV was transmitted to patients in a different private physician's office in New York City; HBV and HCV were transmitted in a pain remediation clinic in Oklahoma; and HCV was transmitted in a hematology/oncology clinic in Nebraska. In all of these cases, transmission to noninfected patients most likely occurred due to exposure to injection equipment contaminated with the blood of one or more patients already infected.
The CDC stressed that the total number of new cases could have been avoided if the health care workers had adhered to basic principles of aseptic technique for preparing and administering parenteral medications. Certification and training programs should reinforce infection-control principles and practices, including aseptic techniques and safe injection practices, said the CDC. The organization directed institutions to enact written polices and procedures to prevent patient-to-patient transmission of bloodborne pathogens, and is working with professional organizations, health departments, and advisory groups toward that end.
Source: CDC: "Transmission of Hepatitis B and C Viruses in Outpatient Settings-New York, Oklahoma, and Nebraska, 2000-2002," Morbidity and Mortality Weekly Report. 52 ( 38 ): 901-906, 2003.