Nocturnal electrobioimpedance volumetric assessment of patients with erectile dysfunction.

OBJECTIVES: Electrobioimpedance volumetric assessment is a procedure that can measure penile length, cross-sectional area, and volume. From these variables, the number and duration of erectile events, volume change, and percentage of volume increase from baseline can be determined. This procedure was performed on patients with erectile dysfunction (ED) and findings were compared with patients with no history of ED. Examples of etiology are reported. METHODS: Two groups of patients with ED were evaluated by electrobioimpedance assessment. Group 1 patients (n = 23), ranging in age from 26 to 60 years (mean 50), were involved in simultaneous electrobioimpedance assessment and duplex Doppler ultrasound penile volume measurements. A tissue correction was derived. Group 2 patients (n = 10), ranging in age from 38 to 64 years (mean 50), used nocturnal electrobioimpedance volumetric assessment (NEVA) at home for 2 consecutive nights. RESULTS: After deriving an expression to correct for tissue volume, simultaneous measurement of penile blood volume by NEVA and duplex Doppler showed that the regression line for study participants and the identity line was not significantly different by analysis of variance. Using NEVA in comparing patients with ED to a reference population with no history of ED, and using a two-tailed Student's t test for means, the data demonstrated a statistically significant (P < or =0.05) difference in the number of erectile events and percentage of volume change over baseline. With NEVA data, it was possible to distinguish arterial insufficiency from veno-occlusive dysfunction. CONCLUSIONS: The present study demonstrates that electrobioimpedance volumetric assessment can be used in patients with ED. Compared with a reference population with no history of ED, the group with ED had fewer nocturnal erectile events that resulted in a smaller increase in penile blood volume change over baseline. Although the time dependence of the measured variables identifies the cause of ED, the application of NEVA to a larger population will allow further analysis of the dynamic information contained in the NEVA data.

Application of nocturnal electrobioimpedance volumetric assessment: a feasibility study in men without erectile dysfunction.

PURPOSE: Electrobioimpedance volumetric assessment is based on the principle of delivering a constant, nondetectable alternating current to a tissue segment. A potential difference measured between the electrodes is converted to impedance. Since impedance changes with variations in blood flow, penile volumetric change is measured noninvasively. We applied this procedure to the development of a new device to evaluate erectile activity nocturnally, and we report our findings in men with no history of erectile dysfunction. MATERIALS AND METHODS: Our study group comprised 10 men with a mean age of 44 years who had no history of erectile dysfunction. The NEVA device consists of a small recording device attached to the upper thigh, and 3 small adhesive electrode pads placed over the hip and on the penile base and glans, respectively. Each subject used the NEVA device for 2 nights. RESULTS: Overall 20 nights of electrobioimpedance volumetric assessment were recorded. Tumescence monitoring revealed 3 to 6 erections per night per subject (mean 3.45) lasting 10 to 50 minutes (mean 17). As determined from the impedance measurements, mean volume change was 14.4 ml. with a 213% mean volume change over baseline. CONCLUSIONS: The new NEVA device is small, comfortable to wear and easy to use. It determines the number and duration of erectile events and percentage increase of blood volume changes during these events in normal men in a noninvasive manner. Future directions of study include a comparison to men with erectile dysfunction and analysis of the dynamic information of the NEVA data.

Respiratory sinus dysrhythmia persists in transplanted human hearts following autonomic blockade.

1. The present study was performed to test whether beat-to-beat cardiovascular control in cardiac allograft recipients resides in cholinergic and/or adrenergic nerves that are intrinsic to the heart. 2. Heart rate (HR) fluctuations synchronous with respiration during spontaneous, double tidal volume and metronome-synchronized breathing were quantified in 13 human heart transplant recipients. We also examined the effects of sequential cholinergic and beta-adrenoceptor (combined) autonomic blockade on respiratory sinus arrhythmia (RSA). We computed RSA amplitude and the correlation between respiration and changes in HR (cardiopulmonary synchronization; CPS). Group means were compared using repeated-measures analysis of variance. Transplant recipients served as their own controls. 3. In the basal state, moderate RSA amplitude and CPS were observed. During cholinergic and combined blockade, we observed no significant change in RSA amplitude, whereas CPS increased significantly during combined blockade (P < 0.05). The amplitude of RSA increased during respiration at double baseline tidal volume, but not at any of the other breathing manoeuvres (P < 0.01). In contrast, CPS increased significantly during both patterned breathing manoeuvres. No significant correlation was seen between mean right atrial pressure and RSA amplitude. In 23% of subjects with low CPS, HR oscillated with arterial pressure. These oscillations were independent of respiration. During all three patterns of respiration, a significant inverse correlation was observed between CPS and pulse pressure (r = -0.53 to -0.73). Thus, as the amplitude of pulse pressure increased, respiration accounted for a smaller percentage of HR variation. 4. In conclusion, RSA persists and the magnitude of CPS increases following combined autonomic blockade. These studies suggest that while RSA after cardiac transplantation is not cholinergically or adrenergically mediated, it may be related to mechanical stretch of the sinus node caused by changes in intrathoracic pressure and perfusion pressure.

Evaluation of penile ultrasonic velocitometry versus penile duplex ultrasonography to assess penile arterial hemodynamics.

OBJECTIVES: A prospective study was performed comparing duplex ultrasonography (DU) and ultrasonic velocitometry (UV), using a new fixed-angle device, in assessing penile arterial hemodynamics. Cavernous arterial peak systolic and end-diastolic flow velocities were measured. METHODS: Twenty-four consecutive patients (mean age 47 years) underwent DU (Ultramark 9 HDI System) and UV (Knoll/MIDUS system) at the same setting by the same technician. After preinjection scanning, all patients received 60 mg of papaverine intracavernosally. Repeat scanning was performed at 5, 10, 15, and 20 minutes. RESULTS: The statistical significance between the two techniques was assessed by examining the correlation. For all patients (n = 24) and all velocity determinations in all patients (n = 554), the equation for the linear regression line is y = 0.952x + 1.453, r = 0.91 (r2 = 0.82) and P < 0.05. CONCLUSIONS: UV is as accurate as DU in measuring peak flow velocities of the cavernous artery. This new fixed-angle device is capable of identifying a vessel without real time imaging. UV is a safe, office-based procedure and scanning is less operator-dependent and easier to learn.

Antibiotics for the acute abdomen.

Antibiotics are only an adjunct to proper surgical therapy for the treatment of the acute abdomen associated with bacterial secondary peritonitis. Upon presentation, all patients require a preoperative dose of antibiotics for prophylaxis against infection of remaining sterile tissues. Patients found intraoperatively to have an established peritoneal infection benefit from an immediate postoperative course of therapeutic antibiotics. A regimen that adequately covers facultative and aerobic gram-negative bacilli and anaerobic organisms is essential. The duration of therapeutic antibiotics is probably best decided on an individual patient basis. The goal of antibiotics is to reduce the concentration of bacteria invading tissues. The pathogens of bacterial peritonitis are influenced by such factors as the patient's pre-existing chronic diseases, state of acute physiologic debilitation, immunocompetence, recent antibiotic use, recent hospitalization, and neutralization of gastric acidity. Intraoperative peritoneal cultures are most useful in patients suspected of having impaired local host defenses. In these patients, all identified organisms, such as Enterococcus or Candida, may be potential pathogens. The common practice of administering empiric and prolonged courses of broad-spectrum antibiotics in patients who manifest persistent signs of inflammation may be more harmful than beneficial. These patients warrant an exhaustive search for extra-abdominal and intraperitoneal sources of new infection. Otherwise, such use of antibiotics may continue to promote the selection of bacteria that are highly resistant to conventional antibiotics and permit the overgrowth of organisms commonly seen with tertiary peritonitis. The best chance of resolving bacterial peritonitis is through early, aggressive surgical management complemented by short courses of potent antibiotics and appropriate physiologic support. Through these efforts, the clinician tries to help the systemic inflammatory response to benefit the host and not become unregulated, result in MOFS, and produce a high mortality.

Ocular effects of exposure to triethylamine in the sand core cold box of a foundry.

OBJECTIVES: To assess the acute and chronic ophthalmological effects of triethylamine exposure among foundry workers. METHODS: Ocular effects on people currently, previously, and never exposed to triethylamine in a foundry cold box were studied at two points in time. The initial phase included an ocular examination with a slit lamp to assess corneal health, a visual acuity test, and a questionnaire to assess vision symptoms. The follow up included measurements of corneal thickness with an ultrasonic pachymeter and the vision symptoms questionnaire before and after the shift and at the beginning and end of the week. Personal air measurements for triethylamine were also obtained during the follow up. RESULTS: The vision symptoms of blurriness, halos around lights, and blue hazy vision occurred more often in currently exposed workers than those previously or never exposed to triethylamine. Air concentrations of triethylamine ranged from < 0.33 mg/m3 to 20.3 mg/m3. Among currently exposed workers, symptoms were more common among those with exposure to > 10 mg/m3 of triethylamine (odds ratio (OR) = 3.0, 95% confidence interval (95% CI) 0.35-25.6). No differences in corneal thickness were found in currently or previously exposed workers and those never exposed. No increase in corneal thickness was found after v before the shift. CONCLUSION: Despite low concentrations of triethylamine and no corneal oedema, workers exposed to triethylamine reported vision symptoms. Possible explanations for these symptoms without corneal oedema are that triethylamine affects ciliary muscle function or that the corneal oedema was transient and not present when corneal thickness measurements were taken. No chronic effects were found in previously exposed workers. Further research is needed to elucidate the mechanism for the reported vision symptoms, which occurred below the current United States eight hour time weighted standard of 100 mg/m3 and the American Conference of Governmental Industrial Hygienists (ACGIH) recommended value at the time of our study of 40 mg/m3. We recommend that air concentrations be maintained to meet the current recommended ACGIH threshold of 4.1 mg/m3.

Hemodynamic, respiratory, and metabolic effects of laparoscopic cholecystectomy.

In 10 patients undergoing laparoscopic cholecystectomy, creation of pneumoperitoneum caused immediate venous hypertension and stasis in the lower extremities as measured by percutaneous catheter and duplex scanning. These changes disappeared after deflation. As measured by spirometry, significant reductions in forced vital capacity of 23% and forced expiratory volume in 1 second of 22% were present 24 hours after surgery, and plasma interleukin-6 levels rose to 18 pg/mL. The visual analogue scale of resting pain increased to a median value of 2.5 postoperatively. When compared with other studies of open cholecystectomy, our results showed fewer restrictions of ventilation, lower cytokine levels, and lower pain scores. The minimal soft tissue trauma and early ambulation after laparoscopic cholecystectomy may decrease the risk of thrombosis despite an acute episode of venous stasis.

Use of a modified van der Pol's oscillator to construct ventricular pressure-volume relations.

Ventricular pressure-volume (PV) loops provide information about ventricular function. Methodologic constraints have limited derivation of PV loops to the laboratory. The present study addresses derivation of PV loops from a direct left ventricular pressure measurement and left ventricular volume derived from continuous cardiac output. The measurements were performed in vivo in intact, innervated, normal canine hearts. Data from a total of 5 dogs and 13 different cardiac work states were analyzed. A nonlinear oscillator, a van der Pol's oscillator, described the PV relationships. Comparison of left ventricular stroke work derived from the van der Pol's oscillator model with that obtained from ultrasound transducers sutured directly to the myocardium demonstrated a linear correlation, close to the identity line, with R2 = 0.90. Modelling of LV PV loops by this technique was similar to loops derived by experimental measurements. This technique could lead to increased clinical uses for PV relationships.

Preoperative optimization of cardiovascular hemodynamics improves outcome in peripheral vascular surgery. A prospective, randomized clinical trial.

The hypothesis that optimizing hemodynamics using pulmonary artery (PA) catheter (preoperative 'tune-up') would improve outcome in patients undergoing limb-salvage arterial surgery was tested. Eighty-nine patients were randomized to preoperative tune-up either in the surgical intensive care unit (SICU) (group 1) or the preinduction room (group 2) or to control (group 3). The tune-up consisted of fluid loading, afterload reduction, and/or inotropic support to achieve predetermined endpoints. Patients with a PA catheter had significantly fewer adverse intraoperative events (p less than 0.05), less postoperative cardiac morbidity (p less than 0.05), and less early graft thrombosis (p less than 0.05) than the control group. The overall study mortality rate was 3.4%, with a mortality rate of 9.5% in the control group and 1.5% in the PA catheter groups. There were no differences in ICU length of stay (LOS), hospital LOS, or total hospital costs, although the percentage of cost from complications was higher in group 3 (p greater than 0.05). In this group of patients, preoperative cardiac assessment and optimization is associated with improved outcome.

Modular indirect calorimeter suitable for long-term measurements in multipatient intensive care units.

OBJECTIVE: The construction of an indirect calorimeter capable of long-term automated sequential monitoring of multiple patients in adult and pediatric ICUs. DESIGN: A prototype system utilizing modular engineering principles, including central respiratory mass spectrometer; validation by organic solvent combustion and nitrogen dilution methods, and Tissot spirometer. SETTING: Surgical and pediatric ICUs in a tertiary care university hospital. RESULTS: When expired minute volume was measured over a range of 4 to 28 L in six intubated patients, expired minute volume measured by the prototype system demonstrated a correlation coefficient of .998 compared with simultaneous expired minute volume measured by a Tissot spirometer. Organic solvent combustion demonstrated a maximum error of 3.8% for oxygen consumption (VO2) and an average error of 1.73 +/- 1.25% (SEM). The maximum error for the respiratory quotient was 3.0%, with an average error of 1.75 +/- 1.07%. VO2 (predicted) vs. VO2 (measured) demonstrated a correlation coefficient of .997. Validation with the nitrogen dilution method over a range of FIO2 from 0.21 to 0.60 demonstrated a maximum error of 7.9%, with an average error of -1.72 +/- 1.1% (n = 51). CONCLUSIONS: Indirect calorimetry by means of a shared system for measurements in multiple patients in ICUs is feasible and cost effective utilizing modular principles and a centralized respiratory gas analyzer.

Low-frequency positive-pressure ventilation with extracorporeal carbon dioxide removal.

Successful use of a new technique, low-frequency positive-pressure ventilation with extracorporeal CO2 removal (LFPPV-ECCR) is presented. The association of fulminant respiratory failure with CNS hemangioblastoma, described in the present patient, has been reported only once before, in 1928.

Continuous cardiac output determination using transtracheal Doppler: initial results in humans.

Transtracheal Doppler, a procedure developed in the authors' laboratory, provides an estimate of cardiac output in endotracheally intubated dogs. The present study reports initial results in humans with a Doppler probe incorporated into an endotracheal tube. The system was first calibrated by empirically determining phi, the angle of the ultrasound beam with respect to the blood velocity vector. For a best least squares fit for phi, aortic diameters can be calibrated over a range of 22-37 mm. The calibration was then tested in a separate group of patients using the same empirically derived angle to calculate cardiac outputs. The transtracheal Doppler cardiac outputs show good correlation with those obtained by thermodilution over a range of cardiac outputs, 2.69-8.62 1/min, R2 = 0.835.

Transtracheal Doppler: a new procedure for continuous cardiac output measurement.

An endotracheal tube with a 5 mm diameter ultrasonic transducer incorporated into its distal end was inserted into the tracheas of six anesthetized dogs. The device provides for ultrasound measurement of aortic diameter and blood velocity in the ascending aorta to obtain cardiac outputs. Because measurements are made proximal to the origins of the aortic arch vessels, total cardiac output is obtained. Procedures for measurement of aortic diameter, aortic blood velocity, and cardiac output are discussed. The resulting data were used to empirically determine the angle of incidence of the ultrasound beam that gave the best least squares fit over a range of thermodilution cardiac outputs. For an angle of incidence of 62.3 degrees, the relationship between cardiac output determined by thermal dilution and by transtracheal Doppler was transtracheal Doppler cardiac output = -.69 + 1.19 thermal dilution cardiac output. R2 = .82. The results from this preliminary assessment of the feasibility of measuring cardiac output in dogs using transtracheal Doppler suggest that additional studies should be pursued. Additional issues that require investigation include confirmation of constancy of human anatomy and demonstration of lack of tracheal trauma from the Doppler equipped endotracheal tube.

Quantitative evaluation of clinical course in surgical ICU patients: the data conform to catastrophe theory.

A response surface for critically ill patients is described. The coordinates of the three-dimensional response surface are two control variables, or state variables, related to aerobic and anaerobic metabolism, and a response variable, the A-VO2 difference. The data conform to a cusp catastrophe manifold. Cardiac insufficiency, adaptive response to stress, and sepsis may be distinguished by this model. The distinction between control and response variables is discussed.

Use of a needle valve variable resistor to improve invasive blood pressure monitoring.

Inaccurate measurements using in-line systems are partly due to the resonance frequency. A variable acoustic resistor designed to change the damping coefficient of these monitoring systems was evaluated under clinical conditions. The device improved pressure transmission characteristics in measurements on 12 of 13 patients. Use of the device and of the bedside step-impulse test for calibration should improve the reliability of in-line blood pressure monitoring.