The effect of meals at different mealtimes on blood pressure and symptoms in geriatric patients with postprandial hypotension

Prevalence of and risk factors for postprandial hypotension in older Chinese men

Objective

To assess the prevalence of and risk factors for postprandial hypotension (PPH) among old and very old Chinese men.

Methods

The study included 349 Chinese men aged 65 and older, grouped into two age categories: group 1 (old) included 163 men aged 65 to 80 years; group 2 (very old) included 186 men aged over 80 years. Blood pressure changes after meals were assessed every 15 min by ambulatory blood pressure monitoring. Symptoms after meal ingestion and after standing up and changes in the baseline condition relative to blood pressure changes were observed continuously. Additional baseline data included body mass index, medical history, and medication use.

Results

The prevalence of PPH was 59.3% overall and was significantly higher in group 2 than group 1 (63.4% vs. 54.6%, P < 0.05). In group 2, the prevalence of PPH after breakfast (33.8%) and lunch (32.1%) were higher than that after supper (20.9%), P < 0.05. Hypertension and age were significant risk factors for PPH (OR = 2.188, 95% CI: 1.134−4.223, P = 0.02; OR = 1.86, 95% CI: 1.112−3.11, P = 0.018, respectively). In contrast, acarbose use was protective against PPH (OR = 0.4, 95% CI: 0.189−0.847, P = 0.017). The decrease in blood pressure during PPH was 20−40 mmHg and the maximum was 90 mmHg. PPH usually occurred at 30−60 min after a meal and lasted 30−120 min.

Conclusions

These findings demonstrate that the prevalence of PPH in men aged over 80 years is significantly higher than those in men aged 65 to 80 years, and the blood pressure decline is also higher for men aged over 80 years. In addition, hypertension and age were main risk factors for PPH in the older men, which suggest that preventing and treating PPH is worthwhile.

The role of NMDA and non-NMDA receptors in the NTS in mediating three distinct sympathoinhibitory reflexes

Cholecystokinin (CCK) elicits a sympathetic vasomotor reflex that is implicated in gastrointestinal circulatory control. We sought to determine (1) the site in the solitary tract nucleus (NTS) responsible for mediating this reflex and (2) the possible involvement of excitatory amino acid (EAA) receptors. In addition, we sought to determine whether the NTS site responsible for mediating the baroreflex (phenylephrine, PE, 10 microg/kg i.v.) and the von Bezold-Jarisch reflex (phenylbiguanide, PBG, 10 microg/kg i.v) overlap with that involved in the CCK-induced reflex (CCK, 4 microg/kg, i.v.), and to compare the relative importance of NMDA and non-NDMA receptors in these reflexes. In separate experiments, the effects of PE, PBG, and CCK on mean arterial blood pressure, heart rate, and splanchnic sympathetic nerve discharge were tested before and after bilateral microinjection into the NTS of the gamma-aminobutyric acid(A) (GABA(A)) agonist muscimol, the EAA antagonist kynurenate, the NMDA receptor antagonist D: (-)-2-amino-5-phosphopentanoic acid (AP-5), the non-NMDA receptor antagonist 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide (NBQX), AP-5 + NBQX, or vehicle. While all treatments (except vehicle) significantly attenuated/abolished/reversed the splanchnic sympathoinhibitory responses to PE, PBG, and CCK, the extent of blockade varied between the different treatment groups. Both NMDA and non-NMDA receptors were essential to the baroreflex and the von Bezold-Jarisch reflex, whereas the CCK reflex was more dependent on non-NMDA receptors. Muscimol, kynurenate, and AP-5 + NBQX significantly attenuated the bradycardic responses to PE and PBG (P < 0.05), whereas AP-5, NBQX, or vehicle did not. The bradycardic responses to CCK remained intact after all treatments. These results suggest that while there is overlap in the area of the NTS responsible for eliciting all three reflexes, NMDA and non-NMDA receptors are recruited differentially for the full expression of these reflexes. The CCK-induced sympathoinhibitory reflex is unique in that it relies predominantly on non-NMDA receptors in the NTS and elicits bradycardic effects that are independent of the NTS.

Postprandial Hypotension in Long-Term Care Elderly Patients on Enteral Feeding

OBJECTIVES

To examine the prevalence and nature of postprandial hypotension (PPH) in orally fed (OF), nasogastric tube (NGT)-fed, and percutaneous endoscopic gastrostomy (PEG)-fed older people.

DESIGN

Prospective comparative study.

SETTING

Nursing and skilled nursing wards of three geriatrics hospitals.

PARTICIPANTS

Three groups (OF, PEG, NGT) of long-term care patients (50 in each cohort) were enrolled.

MEASUREMENTS

Blood pressure (BP) and heart rate measurements were obtained just before lunch and at 15-minute intervals for 90 minutes after the completion of the meal. The meals were similar in caloric content and composition.

RESULTS

PPH was evidenced in 64 (43%) patients. No significant intergroup (OF, PEG, NGT) differences were present. In 68% of PPH patients, the systolic BP (SBP) drop appeared within 30 minutes, and 70% reached their systolic nadir at 60 minutes. In 31%, the SBP drop was registered on only one measurement, whereas in 25%, the drop was detected on five to six measurements. All parameters were without notable intergroup differences.

CONCLUSION

In enterally fed elderly patients (NGT or PEG), the rate and pattern of PPH are similar and not significantly different from that observed in OF patients.