The effect of gag reflex on cardiac sympatovagal tone.

OBJECTIVES: Heart velocity may be influenced by gagging. The medulla oblongata receives the afferents of gag reflex. Neuronal pools of vomiting, salivation and cardiac parasympathetic fibers are very close in this area. So, their activities may be changed by spillover from each other. Using the heart rate variability (HRV) analysis, the effect of gagging on cardiac sympatovagal balance was studied. METHODS: ECG was recorded from 12 healthy nonsmoker volunteer students for 10 minutes in the sitting position between 10 and 11 AM. Gagging was elicited by tactile stimulation of the posterior pharyngeal wall. At 1 kHz sampling rate, HRV was calculated. The mean of heart rate at low and high frequencies (LF: 0.04-0.15; HF: 0.15-0.4 Hz) were compared before and after the stimulus. RESULTS: The mean of average heart rate, LF and HF in normalized units (nu) and the ratio of them (LF/HF) before and after the gagging were 89.9 ± 3 and 95.2 ± 3 bpm; 44.2 ± 5.8 and 21.2 ± 4; 31.1 ± 5.3 and 39.4 ± 3.8; and 1.7 ± 0.3 and 0.6 ± 0.2 respectively. CONCLUSION: Gagging increased heart velocity and had differential effect on two branches of cardiac autonomic nerves. The paradoxical relation between average heart rate and HRV indexes of sympatovagal tone may be due to unequal rate of change in autonomic fiber activities which is masked by 5 minutes interval averaging.

Ageing and ankle pulse pressure.

BACKGROUND: Pulse pressure (PP) is a marker of arterial stiffness. Ageing of the arterial system is accompanied by atherosclerosis of coronary arteries and atherosclerosis of popliteal artery. However, severe impairment of the brachial artery is rare. This study investigates whether there is any significant inter-limb (brachial/ankle) PP difference. METHODS: Blood pressure was measured in a group of young and a group of old non-smoking men; all were free from medication and disease with a mean age of 22 +/- 1.3 and 59 +/- 2 years respectively. The blood pressure was taken while they were in a supine position on three separate occasions. Lower limb pressure was measured by placing the cuff on the calf muscle. For auscultation of Korotkoff sounds the stethoscope was placed on the posterior surface of the internal malleolus. The mean of the second and third readings were rounded off and used for analysis. RESULTS: Significant differences were found between brachial and ankle PP in both groups (p < 0.01). The ratio of brachial PP to ankle PP in the young men was greater than 1. In the old men it was less than 0.15. There was no significant difference between the brachial PP in the two groups, but on both sides the ankle PP was significantly greater in the old men (p < 0.01). CONCLUSIONS: With the ageing of the arterial system, raised PP is more prominent in the lower limb (e.g. ankle). Cuff measurement of blood pressure at this site may be a useful index of peripheral PP changes with ageing.

Evolution of tuberculosis control and prospects for reducing tuberculosis incidence, prevalence, and deaths globally.

CONTEXT: The United Nations Millennium Development Goals (MDGs) are stimulating more rigorous evaluations of the impact of DOTS (the WHO-recommended approach to tuberculosis control based on 5 essential elements) and other possible strategies for tuberculosis (TB) control. OBJECTIVE: To evaluate the prospects for detecting 70% of new sputum smear-positive cases and successfully treating 85% of these by the end of 2005, for reducing TB incidence, and for halving TB prevalence and deaths globally between 1990 and 2015, as specified by the MDGs. DATA SOURCES: TB case notifications (1980-2003) from DOTS and non-DOTS programs and cohort treatment outcomes (1994-2002) reported annually to the World Health Organization (WHO) by up to 200 countries, TB death registrations, and prevalence surveys of infection and disease. STUDY SELECTION: Case notification series that reflect trends in incidence, treatment outcomes from DOTS cohorts, death statistics from countries with WHO-validated vital registration systems, and national prevalence surveys of infection and disease. DATA EXTRACTION: Case reports, treatment outcomes, prevalence surveys, and death registrations from WHO's global TB database covering 1990-2003 to estimate TB incidence, prevalence, and death rates through 2015 for 9 epidemiologically different world regions. DATA SYNTHESIS: TB incidence increased globally in 2003, but incidence, prevalence, and death rates were approximately stable or decreased in 7 of 9 regions. The exceptions were regions of Africa with low (<4% in adults 15-49 years) and high rates (> or =4%) of HIV infection. The global detection rate of new smear-positive cases by DOTS programs increased from 11% in 1995 to 45% in 2003 (with the lowest case-detection rates in Eastern Europe and the highest rates in the Western Pacific) and could reach 60% by 2005. More than 17 million patients were treated in DOTS programs between 1994 and 2003, with overall treatment success rates more than 80% since 1998. In 2003, overall reported treatment success was 82%, with much variation among regions. The highest rates were reported in the Western Pacific region (89%) and lowest rates in African countries with high and low HIV infection rates (71% and 74%, respectively), in established market economies (77%), and in Eastern Europe (75%). To halve the prevalence rate by 2015, TB control programs must reach global targets for detection (70%) and treatment success (85%) and also reduce the incidence rate by at least 2% annually. To halve the death rate, incidence must decrease more steeply, by at least 5% to 6% annually. CONCLUSION: Reduction of TB incidence, prevalence, and deaths by 2015 could be achieved in most of the world, but the challenge will be greatest in Africa and Eastern Europe.