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Biomedical subjects

K S Stone

Publications and source records attributed to K S Stone.

30 records · Page 2Linked to original sources
PubMed1984

Polytetrafluoroethylene versus autogenous vein grafts for vascular reconstruction in contaminated wounds.

A high incidence of dissolution and disruption of infected autogenous vein grafts has been demonstrated. PTFE, on the other hand, has been shown to maintain its structural integrity in the presence of well-entrenched infection, with a relatively small incidence of anastomotic disruption related to host artery necrosis. In addition, PTFE performed as well as autogenous vein when antibiotics were administered. Therefore, PTFE graft material is advocated for controlled clinical trials in patients with contaminated vascular injuries.

Animals↗
PubMed1984

Understanding the calcium channel blockers.

The widespread use of the calcium channel blocking agents provides a significant challenge to the critical care nurse. A thorough understanding of their mechanism of action and the implications of therapy is necessary to provide patients with safe nursing care.

Action Potentials↗
PubMed1981

Jejunal loop interposition: a remedy for failed jejunoileal bypass.

A jejunal loop interposition procedure has been developed for selected post-jejunoileal bypass patients who require repeated hospitalizations for electrolyte imbalance and malnutrition. Twelve patients have undergone interposition of an additional 6 inches of jejunum into the functional segment of bowel with excellent results. Deficiencies in serum albumin, calcium, magnesium and potassium were rapidly corrected following this operation. Desired weight was maintained, and rapid, dramatic improvement in general state of well-being was observed. No intraoperative complications were encountered and the procedure is easily performed.

Follow-Up Studies↗
PubMed1980

Ultrasound as the initial dignostic study in patients with suspected gallstones.

The accuracy, sensitivity, and specificity of ultrasound versus oral cholecystography (OCG) in the preoperative diagnosis of gallstones was studied in 144 patients undergoing cholecystectomy. The 89 per cent accuracy of ultrasound was similar to the 92 per cent achieved with OCG. However, ultrasound was found to have a lower false-positive rate and a greater sensitivity with far fewer indeterminate studies than OCG. A high rate of nonvisualization diminished the usefulness of OCG as a first-line test. Because of a greater sensitivity less tendency for false-positive results, and a moninvasive nature, ultrasound should be the initial diagnostic study of choice in patients with suspected gallstones.

Cholecystography↗
PubMedDate not supplied

Effect of short-duration hyperventilation during endotracheal suctioning on intracranial pressure in severe head-injured adults.

A repeated measures randomized within-group design was used to determine the effectiveness of controlled short-duration hyperventilation (HV) in blunting the increase of intracranial pressure (ICP) during endotracheal suctioning (ETS). A multimodal continuous real-time computerized data acquisition procedure was used to compare the effects of two HV ETS protocols on ICP, arterial pressure, cerebral perfusion pressure (CPP), heart rate, and arterial oxygen saturation in severe head-injured adult patients. The results indicated that short-duration HV for 1 minute, which decreases the PaCO2, reduced ETS-induced elevations in ICP while maintaining CPP. However, it is not clear whether short-duration HV is neuroprotective, particularly in ischemic regions of the brain. Therefore, before a change in practice is implemented on the use of short-duration HV as a prophylactic treatment against ETS-induced elevations in ICP, additional questions on cerebral oxygen delivery and uptake need to be answered.

Adolescent↗
PubMedDate not supplied

Methodologic issues associated with secretion weight as a dependent variable in research using closed-system suction catheters.

BACKGROUND: Closed-system suction catheters (CSSC) were designed to eliminate the need to disconnect the patient from the ventilator during endotracheal suctioning (ETS). During data collection on an NIH-funded study, it was noted that moisture accumulated on the inside of the CSSC and sleeve when attached to the patient for 30 minutes. Because CSSC are not disconnected, they present unique methodologic problems related to measurement of secretions as a dependent variable in clinical research. OBJECTIVES: To describe a valid, reliable, and practical method for weighing secretions obtained during ETS using a CSSC; and to determine the change in weight of a CSSC after its attachment for 30 minutes to a mechanically ventilated patient. METHODS: After being weighed, a CSSC and sputum trap were attached to the endotracheal tube of a mechanically ventilated adult and remained attached for 43 minutes (30 minutes to allow positive end expiratory pressure and oxygenation levels to return to normal and 13 minutes to mimic the time frame for the ETS procedure used in another study). No ETS occurred. The CSSC and sputum trap were then removed and reweighed. RESULTS: A convenience sample consisted of 50 adults who were critically ill and mechanically ventilated. Independent variables included tidal volume, pressure support, body temperature, and respiratory rate. The dependent variable was wet weight of the CSSC, determined by subtracting the preprotocol catheter weight from the postprotocol catheter weight. The mean wet weight for all catheters was 0.5142 +/- 0.1215 grams. In a subset of 37 patients, two wet weights (74 paired observations) were determined. The mean wet weight for these catheters was 0.54014 +/- 0.1404 grams. The paired wet weights were statistically different (t = 2.433; df = 36; p = 0.02). Pearson correlation coefficients and beta coefficients were computed. While tidal volume and pressure support were highly correlated (r = 0.678; p = 0.011), there were no other statistically significant associations. CONCLUSIONS: The amount of secretions is a common dependent variable in ETS research. During the time that CSSC are attached to the patient and ventilator, moisture from either the ventilator's humidification system or the patient accumulates in the CSSC. This wet weight is not actually part of the secretions retrieved during ETS and should not be considered in the actual weight of secretions. Further study on the determinants of wet weight is warranted.

Adult↗
PubMedDate not supplied

The effect of lung hyperinflation and endotracheal suctioning on cardiopulmonary hemodynamics.

The purpose of this study was to examine the effect of sequential lung hyperinflation breaths followed by suction on mean arterial pressure (MAP), cardiac output (CO), pulmonary artery pressure (PAP), and pulmonary airway pressure (Paw) to elucidate the mechanism for the increase in MAP seen with lung hyperinflation and suction. Thirty-four postoperative coronary artery bypass graft patients were randomly exposed to three lung hyperinflation breaths at one of five volumes (tidal volume, 12cc/kg, 14cc/kg, 16cc/kg, and 18cc/kg of lean body weight) using a ventilator followed by 10 s of suctioning repeated for a total of three times. There was a mean increase in MAP (13.71 torr), CO (12.2%), PAP (4 torr), and Paw (23.5 torr) above baseline over the three sequences. The mechanism for the increase in MAP with lung hyperinflation may be attributed to transient increases in intrathoracic pressure, resulting in increased left ventricular preload and CO.

Adult↗
PubMedDate not supplied

Endotracheal suctioning-induced heart rate alterations.

The purpose of the experimental study was to identify mechanical and/or neural factors contributing to the heart rate alterations associated with endotracheal suctioning (ETS). Effects of catheter insertion alone and catheter insertion with the application of negative pressure on the partial pressure of arterial oxygen (PaO2) and heart rate prior to and following vagal blockade with atropine were examined. Eleven newborn swine less than 24 h of age were randomly exposed to (a) suction catheter insertion alone and (b) suction catheter insertion and the application of suction. Preoperatively, the subjects were anesthetized with ketamine and xylazine (.05 mL/kg). The ECG in lead II was recorded on a Gould 2600S recorder. Arterial blood (aB) O2 levels were withdrawn 1 min before and at 20 s, 1 min, 2 min, and 3 min following ETS and analyzed on a calibrated Corning 158 semi-automated aB gas machine. There was a significant decline in PaO2 from baseline at 20 s post ETS in both the no suction and suction protocols, p less than .05. The application of suction caused a greater decline in mean PaO2 (41 torr) compared to no suction (13 torr) at 20 s post ETS which was similar in pattern following vagal blockade (suction: 37 torr; no suction: 2 torr). Following the first pass of the catheter, mean heart rate (HR) declined 14 beats per min with suction and 9 beats per min with no suction. The difference was obliterated following the second pass of the catheter. There was no difference in the HR following vagal blockade.

Animals↗
PubMedDate not supplied

Quantifying the minimum discard sample required for accurate arterial blood gases.

The purpose of this study was to determine the minimum amount of discard sample required to remove all heparinized normal saline from an indwelling arterial catheter to obtain an accurate arterial blood gas (ABG) sample. The pH and partial pressure of oxygen (PO2) and carbon dioxide (PCO2) were adjusted to known values prior to the onset of the study. The discard sample size ranged from zero to 5 cubic centimeters (cc), increasing at 0.5-cc increments. Twenty-nine sets of 11 consecutive discard/ABG samples, totaling 319 ABG specimens, were drawn over 20 minutes. Based on the data, a 2-cc discard is sufficient to guarantee accurate blood gases when withdrawing blood from an arterial catheter with a 1-cc dead space volume.

Blood Gas Analysis↗