Jann Johnston

Suckling-Induced Attenuation of Plasma Cortisol Concentrations in Postpartum Lactating Women

The effect of suckling on serum cortisol concentrations was assessed in postpartum lactating women studied during serial breast feeding sessions 1-24 weeks postpartum. The mean +/- SD serum cortisol concentration at 15 min after the start of nursing, 9.8 +/- 3.89 micrograms/dl, was significantly lower, P = 0.001, than prior to the start of nursing, 13.2 +/- 5.92 micrograms/dl. The decline in the serum cortisol concentrations in the breast feeding women was not due entirely to the normal metabolism of the hormone or the normal circadian variation in cortisol secretion. These studies complement and expand upon a recent report [3] of a significant decrease in plasma adrenocorticotrophic hormone in breast feeding women studied one week postpartum. The neuroendocrine mechanisms responsible for this effect in women have yet to be defined.

Comparison of Insulin Infusion Protocols Targeting 110-140 mg/dL in Patients After Cardiac Surgery.

BACKGROUND Continuous intravenous insulin infusion (CII) following coronary artery bypass graft (CABG) surgery reduces postoperative complications and hospitalization duration. Because of limited data evaluating outcomes of CII with revised glycemic targets (110-140 mg/dL) in cardiac surgery, this study compared efficacy and safety of two different CII protocols having revised targets. SUBJECTS AND METHODS This is a retrospective study comparing two different protocols between August 2009 and March 2010. Protocol 1 consists of four algorithms, and Protocol 2 is a table to adjust CII. Blood glucose (BG) and CII rates were recorded for 48 h postoperatively or CII discontinuation. Efficacy was defined by the percentage of BG values in the target range, and safety was defined by the percentage of BG values<40 and 40-69 mg/dL. RESULTS Protocol 1 (n=117) patients were older (65 vs. 61 years; P=0.006) and had more CABG and fewer valve procedures compared with Protocol 2 (n=130). There were no differences in baseline BG level (149±40.6 vs. 151±38.1 mg/dL), body mass index (30±6.3 vs. 30±6.4 kg/m(2)), hematocrit (28% vs. 28%), percentage of diabetes patients (32% vs. 31%), percentage of patients with glomerular filtration rate of <30 mL/min (5% vs. 6%), CII duration (42 [9-48] vs. 40 [14-48] h), total insulin units received (99 [15-376] vs. 114 [12-457]), hourly insulin rate (median of average rate [range], 2.59 [0-21) vs. 2.96 [0-25] units/h), percentage of BG values 110-140 mg/dL, <40 mg/dL, 40-69 mg/dL, and >180 mg/dL, and BG coefficient of variation (21±6.5 vs. 21±6.1). Shorter time to goal (3.32 [0.22-19.35] vs. 5.03 [0.92-19.80] h; P=0.018) and lower mean BG level (127±12.2 vs. 133±12.1 mg/dL; P<0.001) were noted with Protocol 1. DISCUSSION CII protocols targeting 110-140 mg/dL were effective in achieving revised targets with low hypoglycemia. Despite differences in mean BG level and time to target, each hospital continued using its existing protocols and identified areas for improvement.

Thyrotropin and Gonadotropin Releasing Hormones (Trh and Gnrh) do not Alter Levels of Oxytocin and Oxytocin Does not Change the Response of Luteinizing or Follicle Stimulating Hormones to Gnrh in Humans

Four hundred micrograms of synthetic thyrotropin releasing hormone (TRH) were given intravenously to 4 normal men and 4 normal women, and four weeks later, 1000 micrograms of TRH were administered intravenously to 4 of the 8 individuals and oxytocin (OT) was measured in plasma on both occasions. Following injection of either dose of TRH, OT did not change significantly from baseline. Likewise, synthetic gonadotropin releasing hormone (GnRH), 100 micrograms, administered intravenously to 6 normal men did not alter the levels of OT from baseline. Synthetic OT, 300 mU/minute, administered 30 minutes before and for 90 minutes after injection of GnRH, was without effect on the GnRH-induced rise of luteinizing hormone (LH) or follicle stimulating hormone (FSH) in normal men. We conclude that continuous infusion of OT in pharmacologic concentrations does not alter the pituitary release of LH or FSH in response to GnRH in humans. TRH and GnRH given intravenously do not alter basal levels of OT in the plasma of humans, thus a physiologic role for GnRH or TRH in the neuroendocrine control of OT secretion in humans is unlikely.

Efficacy and Safety of Continuous Insulin Infusion Protocols With Glycemic Targets of 110-140 mg/dL in Patients With and Without Diabetes Following Cardiac Surgery.

Continuous insulin infusion (CII) protocols with glycemic targets 110-140 mg/dl are suggested following cardiac surgery in patients with and without diabetes provided that these targets can be achieved with low risk for moderate (MH) and severe (SH) hypoglycemia.1-4 The purpose of this investigation was to investigate differences in efficacy and safety of these targets according to diabetes status. Glycemic data were collected from 247 consecutive patients treated with 1 of 2 published CII protocols (P1 and P2) targeting blood glucose (BG) 110-140 mg/dl for ≤48 hours following cardiac surgery.5 Diabetes status was defined by medical record documentation or preoperative A1c ≥ 6.5%.6 Protocol efficacy was measured by time to BG target; percentage of BG 70-109, 110-140, 141-180, and >180 mg/dl; and percentage of patients with BG in target after goal achieved. Glycemic variability was determined as the BG coefficient of variation (CV). Protocol safety was defined as percentage of BG 40-69 mg/dl (MH) and <40 mg/dl (SH) and percentage of patients experiencing MH or SH. Statistical analysis was performed using SPSS version 17 software (SPSS Inc, Chicago, IL). With the exception of older age in P1 subjects without diabetes, and higher A1c in P1 patients with and without diabetes, no differences were observed in clinical characteristics (Table 1). Glycemic outcomes were similar for patients with and without diabetes treated with P1, but not P2, where diabetes patients were less likely to have BG within goal, with higher mean BG and more glycemic variability than P2 patients without diabetes. P2 diabetes patients were older, were more obese, required more pressors, and took longer to achieve goal than those without diabetes. When comparing P1 and P2 diabetes groups, there were no differences in the percentage of patients treated with insulin (31% vs 42%) or oral agents (39% vs 49%) prior to admission. P1 diabetes patients had fewer valve procedures, received less pressor therapy, had lower baseline and mean BG, and had more BG within and below goal (Table 1). When comparing nondiabetes groups, P1 patients had more coronary artery bypass grafting (CABG) and fewer valve procedures. P1 versus P2 patients had lower mean BG and more BG below goal. The frequency of both MH and SH was low in all patients, expressed as percentage of BG measures, or as the number of patients experiencing hypoglycemia (Table 1). There were no differences in hospital LOS between the P1 and P2 diabetes (11.6 ± 5.5 vs 13.2 ± 7.4 days, P = .25) and nondiabetes (10.5 ± 4.5 vs 10.8 ± 8.7 days, P = .85) groups. Table 1. Clinical Characteristics of the Study Population. In summary, this study demonstrates the efficacy and safety of 2 CII protocols with glycemic targets of 110-140 mg/dl in patients with and without diabetes following cardiac surgery.1,2,4 Despite noted differences in glycemic outcomes between protocols, mean BG was well within the desired range in all subgroups. The ability to achieve desired BG targets with low incidence of MH and SH in patients with and without diabetes supports suggested glycemic targets of 110-140 mg/dL following cardiac surgery, meeting the criterion that these goals be safely achieved.5