Heart rate variability and plasma catecholamines in patients during opioid detoxification.

It has been shown that rapid opioid detoxification is associated with increased sympathetic activity (SYMP) and plasma catecholamines. Heart rate (HR) variability may provide a noninvasive method of evaluating withdrawal and sympathetic activation caused by the reversal of opioid binding in patients who are opioid dependent. The purpose of this study was to evaluate the relationship between HR variability and plasma catecholamines during opioid detoxification. Patients were anesthetized with propofol, intubated, paralyzed with rocuronium infusion, and ventilated. The bispectral index (BIS) of the electroencephalogram was recorded with the patient awake as well as during propofol anesthesia. SYMP was determined by power spectral analysis of HR variability. Plasma epinephrine and norepinephrine were measured at baseline propofol anesthesia and during naltrexone treatment in eight opioid-dependent patients. Nonopioid-dependent controls (n = 7) were monitored during surgery without naltrexone treatment or measurement of plasma catecholamines. Compared with an awake status, propofol anesthesia significantly decreased the BIS and SYMP in both groups of patients. Controls showed no change from baseline anesthetized levels during surgery. Plasma norepinephrine and epinephrine as well as SYMP increased 300 to 400% (P < .05) during naltrexone treatment in opioid-dependent patients, and the time to peak increase in plasma norepinephrine correlated with the increase in SYMP (r = 0.89, P < .01). These results confirm that opioid detoxification increases plasma catecholamines and SYMP in a similar manner. HR rate variability may provide a low-cost real-time noninvasive method of evaluating the reversal of opioid binding in opioid-dependent patients.     

Growth of children at high risk of obesity during the first 6 y of life: implications for prevention

BACKGROUND: The contribution of familial factors to adiposity in children is poorly understood. OBJECTIVE: The objective was to assess differences in growth in the first 6 y of life in children born to either overweight or lean mothers. DESIGN: The body size and composition of 33 children at high risk and 37 children at low risk of obesity on the basis of the mother's overweight [body mass index (BMI; in kg/m(2)) of 30.2 +/- 4.2 and 19.5 +/- 1.1, respectively] were measured repeatedly from 3 mo to 6 y of age at the Children's Hospital of Philadelphia. RESULTS: At year 2, no significant differences in any measure were observed between the high- and low-risk groups. By year 4, weight, BMI, and lean body mass were greater in the high-risk than in the low-risk children. By year 6, weight was even greater in the high-risk than in the low-risk children (23.4 +/- 6.4 compared with 20.4 +/- 2.1 kg; P < 0.02), and, for the first time, fat mass was greater in the high-risk than in the low-risk children (6.7 +/- 5.7 compared with 3.8 +/- 1.2 kg; P < 0.02). Ten of 33 high-risk children exceeded the 85th percentile of BMI at year 6 compared with 1 of 37 low-risk children (odds ratio = 15.7). Accelerated weight gain was predicted by high-risk group status, greater weight at year 2, and lower family income. CONCLUSION: Anthropometric measures were not significantly different between groups at year 2; weight and lean body mass were greater at years 4 and 6, and fat mass was greater at year 6 in high-risk children.     

Infection following breast reconstruction

Of 33 patients who underwent 49 breast implantations for reconstructive surgery, 8 (24%) patients developed implant infections. All 8 of these patients were among a subgroup of 15 having immediate breast reconstructions with tissue expander implants after simple or modified radical mastectomy (a 53% infection rate). The infection rate increased substantially when bilateral procedures involving implants were performed as opposed to unilateral implants. Nine implants were removed (an overall implant loss rate of 18%). Patients who underwent other breast reconstruction techniques (i.e., including immediate reconstruction with permanent implants or delayed reconstruction with or without tissue expanders) did not develop infection unless they had had simultaneous immediate reconstruction with a tissue expander in the contralateral breast. The most frequently isolated organism was the coagulase-negative staphylococcus. The study concludes that neither the tissue expander nor immediate reconstruction is a risk factor, but the combination may lead to an unacceptable infection rate, especially in the face of bilateral breast procedures.     

Carotid endarterectomy in patients with heparin-induced platelet activation: comparative efficacy of aspirin and iloprost (ZK36374)

Patients with heparin-induced platelet activation who are reexposed to heparin may have recurrent thrombocytopenia, intravascular thrombosis, arterial emboli, or sudden death. To permit carotid endarterectomy in two patients with confirmed heparin-induced platelet activation, we compared the efficacies of aspirin and iloprost, a stable analogue of prostacyclin, in preventing heparin-induced platelet activation. In the first patient, although aspirin prevented both in vitro heparin-induced platelet aggregation (70% without and 7.5% with aspirin) and 14C serotonin release (48% without and 0% with aspirin), intraoperative administration of heparin resulted in an increase in plasma levels of platelet factor 4 from 8 to 260 ng/ml and beta-thromboglobulin levels from 29 to 39 ng/ml. In addition, the circulating platelet count decreased from 221,000 to 174,000 microliters, and 15% spontaneous platelet aggregation was observed. Fortunately, fibrinopeptide A levels remained less than 10 ng/ml intraoperatively, and no thrombotic complications occurred. In the second patient, aspirin did not prevent heparin-induced platelet aggregation in vitro (65% without and 41% with aspirin); however, iloprost (0.01 mumol/L) prevented both in vitro heparin-induced platelet aggregation (59.5% without and 0.0% with iloprost) and 14C serotonin release (56.7% without and 0.0% with iloprost). Therefore, a continuous infusion of iloprost was begun before administration of heparin and was continued until 20 minutes after reversal of heparin with protamine. After intraoperative administration of heparin, plasma levels of platelet factor 4 increased from 19 to 200 ng/ml, and beta-thromboglobulin levels increased from 56 to 76 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)     

Improved patency in reversed femoral-infrapopliteal autogenous vein grafts by early detection and treatment of the failing graft

One hundred two femoral-infrapopliteal bypasses, in which reversed autogenous saphenous vein grafts were used, were performed from January 1978 to July 1984, in 94 patients with severe claudication (14%) or threatened limb loss (86%). Follow-up examinations at 3-month intervals during the first 18 months and at 6-month intervals thereafter were performed to document the return of ischemic symptoms or loss of peripheral pulses. Ankle pressure index and pulse volume recordings were also measured. A decrease in ankle pressure index equal to or greater than 0.2 or a pulse volume recording decrease of 5 mm or more with or without confirmatory symptoms were indications for repeat arteriography. Twenty-two primary graft or anastomotic stenoses were discovered in 19 grafts during follow-up. Seventy-eight percent of these lesions were treated primarily by percutaneous transluminal angioplasty and the remainder were treated by short proximal interposition grafts or patch graft angioplasty. Twenty-five grafts occluded during follow-up and all of these were considered to have failed for purpose of life-table analysis. Stenotic lesions, which were corrected before occlusion, were listed as continuously patent under secondary patency and as failed under primary patency life-table analysis. The secondary graft patency rate was 70% at 5 years, which was significantly higher (p less than 0.01) than the primary patency rate (47%), which was obtained without intervention. This 23% differential represents graft salvage achieved by careful surveillance and is reflected not only by improved patency but also by high limb salvage rates (86%) observed at 5 years.     

Effects of synthetic conjugated estrogens A on sleep quality in postmenopausal women with nocturnal diaphoresis and/or hot flushes: a pilot study

In a single-center, double-blind, placebo-controlled pilot study, patients who received 0.625 mg daily of synthetic conjugated estrogens A experienced a statistically significant reduction in the average number of hot flushes and galvanic skin responses. The polysomnographic change in sleep measures did not reach statistical significance, but the data suggest an overall improvement in sleep quality in the treatment group.     

Contingent screening for Down syndrome--results from the FaSTER trial

OBJECTIVE: Comparison of contingent, step-wise and integrated screening policies. METHODS: Mid-trimester Down syndrome risks were retrospectively calculated from FaSTER trial data. For contingent screening, initial risk was calculated from ultrasound measurement of nuchal translucency (NT), maternal serum pregnancy-associated plasma protein (PAPP)-A and free beta-human chorionic gonadotrophin (hCG) at 11-13 weeks, and classified positive (>1 in 30), borderline (1 in 30-1500) or negative. Borderline risks were recalculated using alpha-fetoprotein, hCG, unconjugated estriol (uE3) and inhibin at 15-18 weeks, and reclassified as positive (>1 in 270) or negative. For step-wise screening, initial negative risks were also recalculated. For integrated screening, a single risk was calculated from NT, PAPP-A and the second trimester markers. RESULTS: There were 86 Down syndrome and 32,269 unaffected pregancies. The detection rate for contingent screening was 91% and false-positive rate was 4.5%; initial detection rate was 60%, initial false-positive rate was 1.2% and borderline risk was 23%. Step-wise screening had 92% detection rate and 5.1% false-positive rate; integrated screening had 88% and 4.9% respectively. CONCLUSION: As predicted by modelling, the contingent screening detection rate for a fixed false-positive rate is comparable with step-wise and integrated screening, but substantially reduces the number needing to return for second trimester testing.     

Development of manganese‐enhanced magnetic resonance imaging of the rostral ventrolateral medulla of conscious rats: Importance of normalization and comparison with other regions of interest

Spinally projecting neurons in the rostral ventrolateral medulla (RVLM) are believed to contribute to pathophysiological alterations in sympathetic nerve activity and the development of cardiovascular disease. The ability to identify changes in the activity of RVLM neurons in conscious animals and humans, especially longitudinally, would represent a clinically important advancement in our understanding of the contribution of the RVLM to cardiovascular disease. To this end, we describe the initial development of manganese‐enhanced magnetic resonance imaging (MEMRI) for the rat RVLM. Manganese (Mn²⁺) has been used to estimate in vivo neuronal activity in other brain regions because of both its paramagnetic properties and its entry into and accumulation in active neurons. In this initial study, our three goals were as follows: (1) to validate that Mn²⁺ enhancement occurs in functionally and anatomically localized images of the rat RVLM; (2) to quantify the dose and time course dependence of Mn²⁺ enhancement in the RVLM after one systemic injection in conscious rats (66 or 33 mg/kg, intraperitoneally); and (3) to compare Mn²⁺ enhancement in the RVLM with other regions to determine an appropriate method of normalization of T₁‐weighted images. In our proof‐of‐concept and proof‐of‐principle studies, Mn²⁺ was identified by MRI in the rat RVLM after direct microinjection or via retrograde transport following spinal cord injections, respectively. Systemic injections in conscious rats produced significant Mn²⁺ enhancement at 24 h (p < 0.05). Injections of 66 mg/kg produced greater enhancement than 33 mg/kg in the RVLM and paraventricular nucleus of the hypothalamus (p < 0.05 for both), but only when normalized to baseline scans without Mn²⁺ injection. Consistent with findings from our previous functional and anatomical studies demonstrating subregional neuroplasticity, Mn²⁺ enhancement was higher in the rostral regions of the RVLM (p < 0.05). Together with important technical considerations, our studies support the development of MEMRI as a potential method to examine RVLM activity over time in conscious animal subjects.     

Oxygen kinetics in preretinal perfluorotributylamine.

Previous studies have relied on various electrodes or probes to monitor preretinal oxygen tension in an effort to gain insight into retinal oxygenation. In order to corroborate and extend the results of such studies, we developed a relatively non-invasive method of determining preretinal oxygen tension using 19F nuclear magnetic resonance (NMR) spectroscopy. Small liquid perfluorocarbon (LPFC) droplets were injected into the preretinal vitreous space of the rabbit eye. The T1 value obtained from the fluorine nuclide could then be used to determine preretinal oxygen tension (PO2) with a high degree of sensitivity, since the fluorine spin-lattice relaxation rate (T1)-1 in LPFCs is directly proportional to PO2 under conditions of no flow and known temperature. In the present study, we investigated the oxygen uptake and clearance rates from small preretinal droplets of the LPFC perfluorotributylamine (FTBA) in response to step changes in arterial PO2. At all FTBA volumes examined (2, 10 and 100 microliters), the oxygen uptake and clearance curves were well approximated by a simple exponential equation with mean time constants 9.8/15.3, 21.4/19.4 and 77.7/45.3 min (uptake/clearance), respectively. Following return to normoxemic (baseline) conditions, FTBA droplets provided a preretinal PO2 of 39.4 +/- 9.2 mmHg (mean +/- S.D., n = 12). The 19F NMR method provides a measure of steady-state preretinal PO2 that independently verifies and complements information obtained using oxygen-sensitive microelectrodes or probes. However, the long time constants for oxygen uptake and clearance, particularly in FTBA volumes on the order of 10 microliters and greater, may represent a practical limitation of this method for determining rapid oxygen flux in the preretinal vitreous space.(ABSTRACT TRUNCATED AT 250 WORDS)