The metabolic demands of internal medicine residency.

BACKGROUND: North American and European accreditation bodies have legislated progressively more strict work hour restrictions for residents in light of evidence that sleep deprivation leads to increased medical errors and decreased wellbeing. The purpose of the study is to determine the physiologic demands of internal medicine training during residency as well as document average sleep (on- and off-call) and physical activity performed using accelerometers. METHODS: A total of 40 internal medicine residents working on the clinical teaching unit at a single center were enrolled in the study from November 2011 to March 2016. There were 22 subjects that completed the study and were included in the analysis. SenseWear PRO 2 armband monitors were worn for 5 consecutive days including one call day. The primary outcomes of the study were to quantify and compare the calories per day, steps per day, METs per hour, hours of activity, hours of sleep, and sleep efficiency for on call versus post-call and non-call days. RESULTS: The average activity per day, calories per day, steps per day and METs per hour for the call day were 7.6 ± 7.6 h, 2647.0 ± 541.1, 11,261.1 ± 2355.9, and 1.7 ± 0.2 respectively. Each of these parameters had a statistically significant F statistic compared to post-call and non-call days. The subjects had a mean of 1.8 ± 2.0 h of sleep per day with a sleep efficiency of 77.3 ± 23.8% for the call day. The F statistic for sleep per day was significant with a p value < 0.001. CONCLUSION: This study shows that overnight call has a substantial impact on multiple metabolic parameters. These findings have potentially important implications on future resident working hour restrictions.

Cytomegalovirus Seropositivity Predicts a Decline in the T Cell But Not the Antibody Response to Influenza in Vaccinated Older Adults Independent of Type 2 Diabetes Status.

Type 2 diabetes mellitus (T2DM) and persistent cytomegalovirus (CMV) infection are postulated contributors to inflammatory processes that impact on the age-related decline in T-cell responses to influenza vaccination. Older subjects with T2DM (n = 30) and healthy aged controls (n = 40) were enrolled and received influenza vaccination in this study. Serum inflammatory markers and CMV serostatus were measured. Pre- to post-vaccination changes in serum antibody titers to the A/H3N2 strain, and levels of granzyme B (GrB, cytotoxic T lymphocytes) in lysates and cytokines in supernatants from influenza A/H3N2-challenged peripheral blood mononuclear cells were measured. We found no difference between the T2DM and healthy groups in the immune responses measured. However, CMV serostatus was a key determinant of the GrB response to influenza challenge; CMV+ subjects had low levels of inducible GrB (iGrB) activity in response to influenza challenge. In contrast, the serum antibody response to the A/H3N2 vaccine strain did not differ with CMV serostatus, and serum levels of the inflammatory marker, ß2-microglobulin, were positively correlated with age, T2DM, and serum IL-10 levels. In conclusion, CMV seropositivity associated with a decline in GrB responses to influenza may predict increased susceptibility to influenza in older adults.

Euglycemic hyperinsulinemia alters the response to orthostatic stress in older adults with type 2 diabetes.

OBJECTIVE: Insulin has opposing influences on blood pressure by simultaneously increasing adrenergic activity and vasodilatating peripheral blood vessels. In this study, we sought to determine whether hyperinsulinemia affects tilt table responses in older adults with type 2 diabetes not complicated by orthostatic hypotension. RESEARCH DESIGN AND METHODS: Twenty-two older adults (mean age 71.7 +/- 1.1) with diet-controlled or oral hypoglycemic drug-controlled type 2 diabetes were recruited. All subjects with orthostatic hypotension, diabetic nephropathy, and sensory neuropathy were excluded. Subjects underwent euglycemic-hyperinsulinemic clamp and placebo "sham clamp" sessions. Sequential euglycemic-hyperinsulinemic clamps were performed for 2 h at 40 mU x m(-2) x min(-1) (low dose) and 2 h at 80 mU x m(-2) x min(-1) (high dose), and each was followed by a head-up tilt table test at 70 degrees C for 10 min. RESULTS: There were no incidents of presyncope during the sham clamp, whereas there were four presyncopal events during both the low-dose and high-dose tilts. Although the low-dose clamp showed no difference in the response between sessions (two-way ANOVA), subjects demonstrated a significantly larger decrease in mean arterial pressure (P = 0.005) and diastolic blood pressure (P = 0.08) during the high-dose tilt. Doppler measures of middle cerebral artery velocity were no different between the two sessions at either dose. CONCLUSIONS: The vasodilatory response to insulin can unmask orthostatic intolerance in older adults with type 2 diabetes, resulting in presyncopal symptoms. This could contribute to orthostatic hypotension in combination with other factors such as hyperthermia, hypovolemia, and adverse effects from medications.

Oral glucose tolerance test reduces arterial baroreflex sensitivity in older adults.

Although postprandial decreases in blood pressure are a common cause of syncope in the older adult population, the postprandial effects of the oral glucose tolerance test on blood pressure and the arterial baroreflex remain poorly characterized in older adults. Therefore, arterial blood pressure and the arterial baroreflex were studied in 19 healthy older adults (mean age 71.7 +/- 1.1 years) who were given a standardized oral glucose load (75 g) or an isovolumetric sham drink during 2 separate sessions. All measures were taken for 120 min after treatment. Baroreflex function was assessed by using the spontaneous baroreflex method (baroreflex sensitivity, BRS). Subjects demonstrated a decrease in BRS after oral glucose that was not seen in the placebo session (two-way analysis of variance, p = 0.04). There was no significant change in systolic, mean, or diastolic blood pressure; together with a drop in BRS, this resulted in a significant tachycardia post glucose (two-way analysis of variance, p < 0.001). We conclude that healthy older adults can successfully maintain blood pressure during an oral glucose tolerance test despite a decrease in arterial BRS. Decreased BRS resulted in a tachycardic response to glucose.

The oral glucose tolerance test induces myocardial ischemia in healthy older adults.

PURPOSE: Postprandial myocardial ischemia has been observed in frail older adults with postprandial hypotension and in patients with severe coronary artery disease, especially after high doses of carbohydrates. The impact of oral glucose on myocardial oxygen supply and demand in healthy older adults without postprandial hypotension or postprandial angina remains unexamined. We hypothesized that oral glucose would result in decreased myocardial oxygen supply relative to demand in a healthy older subject pool free of postprandial hypotension, reversible coronary risk factors and postprandial angina. METHODS: 19 older adults (mean age 71.9+/-1.1 yr) were screened for reversible coronary risk factors. Subjects were given a standardized oral glucose load (75 g) or a sham isovolumetric unsweetened drink during two separate sessions. Indirect measures of oxygen supply (Diastolic Pressure Time Index, DPTI) and demand (Rate Pressure Product, RPP; Systolic Pressure Time Index, SPTI) were obtained from aortic arterial blood pressure waveforms. The Subendocardial Viability Ratio (SEVR, DPTI/SPTI) and DPTI/RPP were also calculated. RESULTS: Oral glucose resulted in decreases in both SEVR (P=0.016) and DPTI/RPP (P=0.028) in the glucose session, indicating a decrease in the relative myocardial oxygen supply to demand. This was due solely to a decrease in myocardial oxygen supply while measures of myocardial oxygen demand did not change significantly. CONCLUSIONS: Oral glucose decreases myocardial oxygen supply in older adults free of severe coronary artery disease and without postprandial hypotension. This represents a previously unrecognized complication of oral glucose tolerance tests in healthy older adults.