Comparison of oxygen therapy with nasal continuous positive airway pressure on Cheyne-Stokes respiration during sleep in congestive heart failure.

STUDY OBJECTIVES: Both oxygen therapy and nasal continuous positive airway pressure (CPAP) therapy have independently been shown to be effective in the treatment of Cheyne-Stokes respiration (CSR) in patients with congestive heart failure (CHF). The purpose of this study was to compare the short-term effects of oxygen therapy and nasal CPAP therapy on CSR in a group of stable patients with severe CHF. DESIGN: Prospective, randomized, controlled trial. SETTING: University hospital. PATIENTS: Twenty-five stable patients (mean [+/- SD] age, 56 +/- 9) with CHF and a mean left ventricular ejection fraction (LVEF) of 17 +/- 0.8%. INTERVENTIONS AND MEASUREMENTS: All patients had a right heart catheterization prior to the study and an echocardiogram performed to measure LVEF. In addition, all patients had an initial sleep study to identify the presence of CSR. Sleep studies included continuous recordings of breathing pattern, pulse oximetry, and EEG. Those patients identified as having CSR were randomized to a night on oxygen therapy (2 L/min by nasal cannula) and another night on nasal CPAP therapy (9 +/- 0.3 cm H(2)O). RESULTS: Fourteen of the 25 patients (56%) studied had CSR (apnea hypopnea index [AHI], 36 +/- 7 events per hour) during their initial sleep study. Nine of the 14 patients with CSR completed the study. When compared with baseline measurements, both oxygen therapy and nasal CPAP therapy significantly decreased the AHI (from 44 +/- 9 to 18 +/- 5 and 15 +/- 8 events per hour, respectively; p < 0.05), with no significant difference between the two modalities. The mean oxygen saturation increased significantly and to a similar extent with oxygen therapy and nasal CPAP therapy (from 93 +/- 0.7% to 96 +/- 0.8% and 95 +/- 0. 7%, respectively; p < 0.05), as did the lowest oxygen saturation during the night (from 80 +/- 2% to 85 +/- 3% and 88 +/- 2%, respectively; p < 0.05). In addition, the mean percent time the oxygen saturation was < 90% also improved with both interventions (from a baseline of 17 +/- 5 to 6 +/- 3% with oxygen therapy and 5 +/- 2% with nasal CPAP therapy; p < 0.05). When compared with baseline measurements, the apnea-hypopnea length, cycle length, circulation time, and heart rate did not significantly change with either oxygen therapy or nasal CPAP therapy. Total sleep time and sleep efficiency decreased only with nasal CPAP therapy (from 324 +/- 20 to 257 +/- 14 min, and from 82 +/- 3 to 72 +/- 2%, respectively; p < 0.05). The arousal index, when compared with baseline, remained unchanged with both oxygen therapy and nasal CPAP therapy. CONCLUSION: CSR occurs frequently in stable patients with severe CHF. In addition, oxygen therapy and nasal CPAP therapy are equally effective in decreasing the AHI in those CHF patients with CSR.

The effect of closure processing on the microbial inactivation of biological indicators at the closure-container interface.

Two biological indicators are routinely used by the Hospital Products Division to demonstrate the sterilization of the closure-container interface. The use of a moist heat (Clostridium sporogenes) and a dry heat (Bacillus subtilis) biological indicator allows a better understanding of the parameters that impact sterilization of the closure-container system. The ability to sterilize a given closure-container interface is defined in large part by closure moisture and product time above 100 degrees C. The data will demonstrate several different means to alter these two key factors, thereby enhancing sterilization of the closure-container interface. A categorization of closure types and processing parameters allows for more efficient cycle development in the R&D facility and a higher success rate for the final subprocess validation in the manufacturing steam vessels.

Effects of noninvasive positive pressure ventilation on gas exchange and sleep in COPD patients.

STUDY OBJECTIVE: The role of nocturnal noninvasive positive pressure ventilation (NPPV) in the treatment of patients with hypercapnic COPD remains controversial. Beneficial effects reported after prolonged use have included an improvement in gas exchange. The purpose of this study was to examine the short-term effects of NPPV on gas exchange and sleep characteristics in patients with hypercapnic COPD and to determine if similar acute changes in gas exchange are associated with improved sleep quality. DESIGN: Prospective, randomized, controlled trial. SETTING: Sleep laboratory of a university hospital. PATIENTS: Six patients with severe but stable hypercapnic COPD (PaCO2=58+/-4 [SE] mm Hg). Mean age was 63+/-6 (SD) with an FEV1=0.58+/-0.09 L. INTERVENTIONS AND MEASUREMENTS: Patients were studied in the sleep laboratory for a total of three nights. On nights 2 and 3, arterial catheters were placed prior to the study. Following an acquaintance night, patients were randomized to either a control-sham night on 5 cm H2O nasal continuous positive airway pressure (CPAP) or an NPPV night using a ventilatory support system (BiPAP; Respironics Inc; Murrysville, Pa) at previously determined optimal settings. The third night consisted of the opposite for each patient, either a control-sham or an NPPV night. On the second and third nights, three arterial blood gas readings were obtained: (1) baseline wakefulness; (2) non-rapid eye movement (NREM) sleep; and (3) rapid eye movement (REM) sleep. RESULTS: During NREM sleep, NPPV in comparison to the control-sham night on low level CPAP caused no significant change in PaCO2 (60+/-4 to 59+/-3 mm Hg [p=0.6]) and a decrease in PaO2 (96+/-9 to 72+/-5 mm Hg [p=0.04]). During REM sleep, NPPV in comparison to the control-sham night on low level CPAP caused no significant change in either PaCO2 (63+/-7 to 57+/-2 mm Hg [p=0.46]) or PaO2 (67+/-7 to 75+/-8 mm Hg [p=0.51]). Sleep efficiency and total sleep time (TST) increased significantly with NPPV in comparison to the control-sham night on low level CPAP: from 63+/-7% to 81+/-4% (p<0.05) and from 205+/-32 to 262+/-28 min (p<0.05), respectively. Sleep architecture, expressed as a percentage of TST, was unchanged on the NPPV night compared to the control-sham night on low level CPAP. The number of arousals during the night was also unchanged with NPPV in comparison to the control-sham night on low level CPAP (45+/-11 to 42+/-9 [p=not significant]). CONCLUSIONS: NPPV acutely improved sleep efficiency and TST in patients with hypercapnic COPD without significantly improving gas exchange. Other sleep parameters, including sleep architecture and the number of arousals during the night, remained unchanged during NPPV. These data suggest that the beneficial effects of NPPV in patients with hypercapnic respiratory failure are not solely due to an improvement in gas exchange but may be more complex with other factors potentially having contributing roles.

The effect of formulation of parenteral solutions on microbial growth--measurement of D- and z-values.

In order to assess the sterilization conditions for parenteral solutions, the microbial inactivation kinetics of steam resistant spores of Clostridium sporogenes were evaluated. The D-value or death rate kinetics as well as z-values were obtained for several formulation categories of solutions employing a miniature steam retort. Amino acid and heparin solutions provided appreciable microbial resistance as demonstrated by resulting high D- and low z-values. The addition of electrolytes to carbohydrate solutions resulted in increased microbial resistance compared to carbohydrate solutions without electrolytes. A categorization of solutions and their potential impact on microbial thermal resistance will be presented.

Identification of a male-specific histocompatibility protein on preimplantation porcine embryos.

An indirect immunofluorescence assay was used to detect the presence of male-specific protein(s) on various stages of preimplantation porcine embryos. Embryos were collected at slaughter from the reproductive tracts of day-2.5, -4, -5, -6, and -8 (day 0 = first day of estrus) sows and gilts. Embryos were placed in medium containing an anti-male primary antibody, washed, and transferred to culture drops containing a fluorescein isothiocyanate (FITC)-labeled secondary antibody. Embryos were classified as either fluorescent (H-Y positive) or nonfluorescent (H-Y negative), transferred to coded drops, and karyotyped to examine sex chromosomes. A total of 91 eight-cell to blastocyst stage embryos were evaluated; of these, 46% were classified as fluorescent and 54% as nonfluorescent. Of readable metaphase spreads (65%) from these embryos, 81% (48 of 59, P less than 0.005) were correctly sexed by immunological detection of the male-specific antigen. Although 13% (2/15) of four-cell embryos evaluated were classified as fluorescent, the accuracy with which embryos at this stage were sexed by detection of H-Y antigen was not different from 50%. Fifty percent of eight-cell embryos were classified as H-Y positive with 78% of embryos correctly sexed. It was concluded that the eight-cell embryo is the earliest stage of development for which there is evidence for expression of H-Y antigen. Detection of the male-specific protein was difficult at the expanded blastocyst stage.

Partial atrioventricular canal in association with Ebstein's anomaly. Echocardiographic diagnosis and surgical correction.

Echocardiography was used to diagnose the presence of both Ebstein's anomaly and partial atrioventricular canal in the case of a 20-year-old man who presented for evaluation of supraventricular tachyarrhythmias. The diagnosis was confirmed at surgery with successful surgical repair.

Survival and probability of cure without and with operation in complete atrioventricular canal.

Actuarial analysis based on postmortem examination of patients who had been treated nonsurgically for complete atrioventricular (A-V) canal defect shows that only 54% survive to 6 months of age, 35% to 12 months, 15% to 24 months, and 4% to 5 years of age. Our surgical experience since 1975 in 39 patients confirms the idea that primary repair is feasible in small infants. The highest risk of hospital death is when the operation is done in the early months of life; it falls to 17% by age 12 months. Between 1967 and October, 1976, the five-year survival rate among patients leaving the hospital alive after repair was 91%. The age-specific probability of "surgical cure" of patients operated upon for complete A-V canal (alive five years later with mean pulmonary artery pressure less than 25 mm Hg) is maximal at 73% when the operation is done at about 14 months of age. Urgent earlier repair is frequently necessitated by the life history of the disease.

Primary repair of complete atrioventricular canal in patients less than 2 years old.

Twenty-seven consecutive patients less than 2 years of age underwent primary intracardiac repair of complete atrioventricular (A-V) canal. Three (19 percent) of the 16 operated on after January 1, 1975 died in the hospital, a smaller proportion than the 8 of 11 patients who died in the hospital after operation between 1972 and 1975 (P = 0.005). The date of operation as a continuous variable is also related to the probability of hospital death (P = 0.016). Age at operation was not related to hospital mortality among the total group of 27 infants, nor were the anatomic characteristics of the anterior and posterior bridging leaflets, the location and size of the interventricular communications or the duration or technique of profound hypothermia (total circulatory arrest versus low perfusion flow rate). The improved results in the 16 patients operated on since January 1, 1975 are believed to be primarily the result of an improved ability to construct "mitral" and "tricuspid" valves from the common A-V valve. Fourteen of the 16 hospital survivors are alive and well 5 to 60 months after operation. These results and the natural history of patients with this malformation indicate that there should be no change in the policy of performing elective intracardiac repair before age 2 years and primary repair rather than pulmonary arterial banding when operation is required in the early months of life.

Effect of electrostatic fields on the chromosomes of Ehrlich ascites tumor cells exposed in vivo.

An effect of electrostatic fields on the chromosomes of Ehrlich ascites tumor cells exposed in vivo has been demonstrated. Cells exposed to horizontal electrostatic fields for two weeks had almost a threefold increase in the percentage of abnormal chromosomes when compared to control cells or cells exposed to vertical electrostatic fields for the same period. Extended exposure times of 4--15 weeks resulted in the disappearance of the aberrant chromosomes. It is suggested that the effected cells were incapable of cellular replication resulting eventually in their disappearance via cell death.

In vivo bioelectrochemical changes associated with exposure to extremely low frequency electric fields.

One hundred seventy-four 21- to 24-day-old Sprague-Dawley rats were continuously exposed to a 60 Hz electric field of 150 V/cm for one month in ten separate experiments. Biological effects observed included depressed body weights, serum corticoids, and water consumption. The findings are tentatively in terpreted as indicating that a power frequency electric field is a biological stressor. The observed effects cannot be a consequence of Joule heating and therefore indicate that electric fields can influence biological systems either at the systemic level, or at the cellular level via electrochemical alteration of the microenvironment.

Antifungal properties of electrically generated metallic ions.

A qualitative and quantitative investigation was undertaken to study the susceptibility of unicellular eucaryotic organisms (yeasts) to metallic cations generated by low levels of direct current. Results were characteristic of effects obtained previously using clinical and standard bacteria test organisms. The present study demonstrated that anodic silver (Ag(+)) at low direct currents had inhibitory and fungicidal properties. Broth dilution susceptibility tests were made on several species of Candida and one species of Torulopsis. Growth in all isolates was inhibited by concentrations of electrically generated silver ions between 0.5 and 4.7 mug/ml, and silver exhibited fungicidal properties at concentrations as low as 1.9 mug/ml. The inhibitory and fungicidal concentrations of electrically generated silver ions are lower than those reported for other silver compounds.