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Biomedical subjects

E Sankaranarayanan Prakash

Publications and source records attributed to E Sankaranarayanan Prakash.

11 recordsLinked to original sources
PubMed2006

A novel tilt table testing protocol for investigating patients suspected to have neurally mediated syncope.

We have observed that a series of 3 Valsalva maneuvers performed at 1-minute intervals between the 15th and 18th minute of a drug-free tilt table test resulted in intense presyncope and hypotension in a 32 yr old male with micturition syncope. In contrast, five apparently healthy subjects tolerated a 70 degree head-up tilt table test for 45 min with five Valsalva maneuvers incorporated into the testing protocol. Thus, we hypothesize that the use of a series of Valsalva maneuvers during a drug free head-up tilt table test might improve the diagnostic yield without compromising test specificity in patients suspected to have neurally mediated syncope.

Adult↗
PubMed2006

Effect of deep breathing at six breaths per minute on the frequency of premature ventricular complexes.

Although the effect of reflex increase in vagal tone on the frequency of premature ventricular complexes (PVC) is known, the effect of timed deep breathing on the frequency of PVC has not been reported. We serendipitously discovered that deep breathing at six breaths per minute abolished PVC in an 18-year-old female with frequent PVC, anxiety, and palpitations. In five of a series of 10 consecutive patients with frequent (> or = 10/min) unifocal PVC, deep breathing at 6 breaths/min reduced the frequency of PVC by at least 50%. This is possibly due to increased vagal modulation of sinoatrial and atrioventricular node. However, factors predicting the response to deep breathing, and the mechanisms involved need to be studied in a larger number of patients.

Adolescent↗
PubMed2006

What does one mean by "arterial blood oxygenation?".

We used the following question in a large classroom session attended by undergraduate medical students and doctors with a Bachelor of Medicine and Bachelor of Surgery (MBBS) degree (240 in all) to test for conceptual understanding as to what constitutes arterial blood oxygenation. The question read as follows: Which one of the following physiological parameters taken alone tells you that arterial blood oxygenation in a critically ill patient is satisfactory? A. (Alveolar-arterial) O(2) gradient=10 mmHg. B. Partial pressure of O(2) in arterial blood=95 mmHg. C. O(2)saturation of hemoglobin>90%. D. Blood hemoglobin concentration=12 g/dl. Only 25 of 240 students correctly indicated that none of the above parameters taken alone could give us this information. Once students turned in their answers, we presented five examples illustrating how none of the above answers could be used alone to assess arterial blood oxygenation. Students were then asked to provide written feedback on their understanding of this topic. The majority of students indicated that they were satisfied that they got rid of a misconception.

Anemia↗
PubMedDate not supplied

Cardiovascular autonomic regulation in subjects with normal blood pressure, high-normal blood pressure and recent-onset hypertension.

1. In the present study, we tested the hypothesis that heart rate variability (HRV) is reduced in recent-onset hypertension and that pressor responses to standard autonomic reflex tests are not any different in hypertensives compared with normotensives. We also hypothesized that subjects with high-normal blood pressure (BP) would be distinguishable from normotensives on the basis of short-term HRV indices. 2. Three groups of subjects, each consisting of 15 men and 10 women, were examined. The first group consisted of subjects with recent-onset hypertension who were not taking antihypertensive medication (mean (+/-SD) age 50 +/- 12 years; BP >/= 140/90 mmHg), the second group consisted of subjects with high-normal BP (mean age 46 +/- 13 years; BP 130-139/85-89 mmHg) and the third group consisted of subjects with normal BP (mean age 48 +/- 12 years; BP < 120/80 mmHg). The aim was to characterize the autonomic state in each group. 3. Blood pressure, heart rate (HR), indices of short-term HRV during supine rest and quiet standing, HR variation during timed deep breathing (HRVdb) and pressor responses to the cold pressor test and sustained isometric handgrip were compared between the groups. 4. Although the three groups were comparable (P > 0.1) in terms of mean HR and low-frequency (LF) power expressed in normalized units at rest and during quiet standing, the standard deviation of normal-to-normal RR intervals (SDNN) during supine rest, LF and high-frequency spectral powers during supine rest and HRVdb were lowest in hypertensives (P </= 0.05 for each), indicating diminished baroreflex modulation of RR intervals in hypertensives. 5. In contrast, LF power was highest in subjects with high-normal BP (P </= 0.05) during supine rest and this is possibly because of higher BP variability. 6. The results suggest that HRVdb provides a simple measure of cardiac vagal effects in hypertensives, the rate-pressure product provides a simple measure of overall HRV in hypertensives and, in clinical hypertension, the arterial baroreflex mechanism is reset to maintain a higher BP through diminished vagal modulation of HR and possibly heightened sympathetic outflow to the heart and resistance vessels.

Adult↗
PubMedDate not supplied

Correlation between body mass index and blood pressure indices, handgrip strength and handgrip endurance in underweight, normal weight and overweight adolescents.

In the present study, we investigated the correlation between body mass index (BMI), blood pressure (BP) indices and indices of physical fitness in apparently healthy subjects aged 14-18 years. We obtained data from 145 (105 males and 40 females) and assessed the correlation between BMI, and heart rate, systolic pressure (SP), diastolic pressure (DP), pulse pressure (PP), mean arterial pressure (MP), rate-pressure product, endurance in the 40 mm Hg test, handgrip strength (HGS), and handgrip endurance. Subjects with BMI <18.5 kg/m2, 18.5-25 kg/m2 and >25 kg/m2 were classed as underweight (65 males and 9 females), normal weight (27 males and 20 females), and overweight (13 males and 11 females) respectively. In view of gender differences in autonomic regulation, data of male and female subjects were analyzed separately. We used analysis of variance to compare differences between the three groups. Correlation between BMI and other indices was tested using Pearson's correlation coefficient. A P value <0.05 was considered statistically significant Both SP and DP were highest in overweight and least in underweight male subjects (P<0.05 for both), whereas in females, differences in DP alone were statistically significant (P<0.05). In underweight male subjects, there was a positive correlation between BMI and SP, DP, PP, MP and HGS (P<0.05 for all). There was a positive correlation between BMI and SP in overweight male subjects (r = 0.5 P = 0.07, n = 13). A positive correlation was observed between BMI and rate-pressure product (r = 0.5, P = 0.45, n = 11) and BMI and HGS (r = 0.6, P = 0.05, n = 11) in overweight females. Our observations indicate that there are gender differences in the correlation between BMI and BP indices especially in underweight and overweight subjects. The observed differences between the three groups and gender differences in correlation between BMI and BP indices may be due to differences in autonomic function and or energy metabolism.

Adolescent↗