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Biomedical subjects

N S Yeston

Publications and source records attributed to N S Yeston.

At least 19 recordsLinked to original sources
PubMed1999

The relationship of pre mortem diagnoses and post mortem findings in a surgical intensive care unit.

OBJECTIVE: To evaluate pre- and post mortem diagnoses and determine their relationship and the discrepancy rate. DESIGN: Retrospective, descriptive chart review. SETTING: A 36-bed surgical intensive care unit (ICU) of an academic, tertiary care center. PATIENTS: 149 adults who died in the ICU and had an post mortem examination. INTERVENTIONS: Review of the medical record for the ICU course, hospital discharge/death summary, major and minor clinical diagnoses, and the cause of death were directly compared with the major and minor diagnoses and cause(s) of death determined by post mortem examination. MEASUREMENTS AND MAIN RESULTS: Major and minor clinical diagnoses were categorized by the Goldman method and compared with post mortem findings to determine the discrepancy rate. Patients were categorized by the primary surgical service that provided medical and surgical care. Sixty-one (41%) patients had discrepancies uncovered at post mortem examination, of which 20 had two discrepancies. Twenty-three percent of the 149 patients had errors categorized as major and 18% as minor. Overall, 85% of the major errors were undiagnosed infectious processes. Complete agreement between the pre and post mortem diagnoses was present in 58% and varied with the surgical population: trauma group (86%) and cardiac surgery (69%) vs. the transplantation group (17%). Those with longer lengths of stay in the ICU were more likely to develop and, subsequently, have a major error discovered post mortem. Conversely, those who died early (<48 hrs), were less likely to have an undiagnosed disease at post mortem examination and, thus, more likely to have complete agreement between pre and post mortem findings. CONCLUSIONS: The overall discrepancy rate as well as the infectious discrepancy rate between pre mortem clinical diagnoses and post mortem findings were substantially higher in a surgical ICU compared with a hospital-wide population. The majority of these discrepancies were undiagnosed infections. The length of time spent in the ICU before death appeared to influence the rate of errors uncovered at the post mortem examination, suggesting that a longer ICU course, as well as the particular type of surgical patient population, may increase the chance of developing an infectious process, only to be uncovered at post mortem examination.

Adult↗
PubMed1994

Pressure sores no more: a quality improvement project.

Review of staff performance in the area of pressure sore prevention revealed that nursing practice was adequate. But the staff's belief that it could do a better job provided the impetus for a quality improvement project. Based on research data a planned change was implemented, and follow-up study reflected positive outcome results. This successful project integrated the concepts of research, cost effectiveness, and patient outcome.

Beds↗
PubMed1993

Effect of dynorphin microinjection in the anterior hypothalamus (AV3V) region on the hemodynamic response to hemorrhage in the rat.

The region surrounding the anteroventral part of the third ventricle (AV3V) is important for the regulation of cardiovascular homeostasis. In the present study we investigated the effect of the kappa-opioid receptor agonists dynorphin A-(1-17) and dynorphin A-(1-13) microinjected into the AV3V region on mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), and left ventricular stroke work (LVSW) during fixed-volume hemorrhage in conscious rats. During fixed-volume hemorrhage (8 ml/300 g), dynorphin A-(1-17) (6 nmol), microinjected into the AV3V, significantly decreased MAP up to 30 min postinjection (P < 0.05). Recovery of MAP, SV, and LVSW in the dynorphin A-(1-17) group following hemorrhage was found to be significantly attenuated compared to that in animals receiving microinjection of normal saline (NS) vehicle into the AV3V (P < 0.05). Hypothalamic microinjection of dynorphin A-(1-13) (6 nmol) also attenuated the recovery of SV following hemorrhage compared with the NS group (P < 0.05). No significant effects were observed on HR or CO following microinjection of dynorphin into the AV3V region. The results of this study suggest that activation of the kappa-opiate receptor system in the AV3V region of the hypothalamus can attenuate the compensatory cardiovascular responses to hemorrhage.

Animals↗
PubMed1992

Validation of respiratory mechanics software in microprocessor-controlled ventilators.

BACKGROUND AND METHODS: Several microprocessor-controlled ventilators, available for clinical use, contain optional computer software programs capable of performing near-instantaneous determinations of airway resistance and lung compliance. This study was undertaken to determine the validity of the measurements for airway resistance and lung compliance obtained by the software packages on three microprocessor-controlled ventilators. Three ventilator models were studied. An artificial ventilator-patient circuit was constructed using a test lung and an endotracheal tube. Airway pressure and gas flow curves were recorded using conventional means. Static lung compliance and airway resistance were calculated using standard equations, while automated measurements were obtained from the ventilators. The following parameters were then varied to simulate a wide variety of clinical situations: tidal volume, peak inspiratory flow rate, respiratory rate, endotracheal tube, and test lung compliance. RESULTS: Automated measurements were highly correlated with values obtained manually (resistance: Puritan-Bennett 7200a r2 = .94, Bear 5 r2 = .98, Veolar r2 = .96; compliance: 7200a r2 = .93, Bear 5 r2 = .97, Veolar r2 = .97). Calculated limits of agreement between the two methods demonstrate that although not in absolute agreement, the software-determined values for airway resistance and lung compliance differed from the manually derived values in a ventilator-specific, predictable fashion. CONCLUSIONS: The correlation and agreement demonstrated between values of airway resistance and lung compliance measured by the respiratory mechanics software packages and those values derived manually suggest that these software packages may be useful for measuring trends, as well as responding to treatment in the clinical setting. These results apply only to the controlled, mechanical ventilation mode. Further studies are indicated to validate this software in patients capable of generating spontaneous breaths.

Airway Resistance↗
PubMed1991

The effect of haloperidol on ventricular fibrillation threshold in pigs.

Ventricular fibrillation has been observed in association with the administration of haloperidol. This study was designed to determine the effect of intravenous haloperidol on ventricular fibrillation threshold (VFT). VFT's were determined prior to and 15 min. following an intravenous infusion of haloperidol (50 mg administered over 10 min.) in five pigs anaesthetized with alpha-chloralose. VFT's were determined using a single stimulus method. Mean arterial pressure (MAP), heart rate (HR), and electrocardiogram (ECG) were monitored continuously. Mean VFT (mA) at baseline and following haloperidol infusion was 50.2 +/- 4.6 and 65.1 +/- 12.8, respectively (P less than 0.05). Mean MAP (mmHg) at baseline and following haloperidol infusion was 127 +/- 32 and 107 +/- 23, respectively (P less than 0.05). Haloperidol infusion did not significantly influence mean HR, QRS duration or corrected QT interval. Intravenous haloperidol increases VFT and decreases MAP in pigs. In this model, haloperidol may offer protection against ventricular fibrillation. Further study is required to determine the clinical significance of the antifibrillatory effect of haloperidol.

Animals↗
PubMed1990

Does pH paper accurately reflect gastric pH?

The testing of gastric pH in the ICU has become the standard of care for most critically ill patients. It has been demonstrated that maintaining a gastric pH of greater than 3.5 confers protection from upper GI bleeding, while lesser pH values subject the patient to hemorrhagic risk. We compared nasogastric pH, as measured by pH electrode, to color-scaled pH paper in 16 critically ill patients hospitalized 3 to 10 days in the surgical ICU. Statistical analysis of 370 gastric specimens revealed a sensitivity of 66.7% and specificity of 94.5% when a paper pH (pH[p]) of greater than or equal to 4 was used as the therapeutic end-point. The sensitivity and specificity of the same pH(p) for clear buffered solutions were 100%. We conclude that the use of pH(p) lacks the clinical accuracy for determining the effects of therapy for the prophylaxis of stress gastritis and will lead to a significant degree of undertreatment. This lack of accuracy is not due to observer error or the quality or age of the testing paper. Our results suggest that if the measurement of gastric pH by pH(p) analysis is to be used as a guide for the prevention of stress-related hemorrhage, a more accurate method of monitoring may be warranted.

Critical Care↗
PubMed1989

Intra-aortic balloon counterpulsation in high-risk cardiac patients undergoing noncardiac surgery.

Patients undergoing noncardiac general surgical procedures after coronary artery bypass surgery have reduced mortality compared with those operated on without prior revascularization. The urgency of the noncardiac procedure and the potential reconstructability of the coronary artery anatomy may mitigate against timely revascularization. We report the successful outcome of prophylactic intra-aortic balloon counterpulsation in three patients with coronary artery disease and impaired left ventricular function undergoing noncardiac surgical procedures. Intra-aortic balloon counterpulsation may provide myocardial protection in high-risk cardiac patients requiring noncardiac surgery initially. A review of the literature is discussed.

Aged↗
PubMed1988

Delayed recognition of vascular complications caused by central venous catheters.

Three patients are described in whom vascular complications occurred after placement of central venous catheters. Inappropriate catheter length and site of cannulation, catheter movement, and unsuitable catheter material can lead to complications. Guidelines for cannulation of central veins are defined, and recommendations for chest roentgenography, which could result in early recognition of catheter misplacement, are provided.

Adult↗
PubMed1988

Total parenteral nutrition-induced cyclic hypercapnia.

Excessive rates of carbohydrate infusion during total parenteral nutrition (TPN) have been reported to cause hypercapnia leading to respiratory failure or inability to wean from a ventilator. This case history illustrates the hitherto unreported syndrome of cyclic hypercapnia resulting from high rates of carbohydrate infusion during peak TPN flow rates when TPN was provided in a cyclic fashion. The patient was given TPN daily over an 18 1/2-h period followed by 5 1/2 h without nutritional support. Elevated CO2 production, increased respiratory quotient, hypercapnia, and inability to wean from a ventilator occurred during peak cycle TPN flow rates. When the same carbohydrate load was infused continuously over a 24-h period, CO2 production, respiratory quotient and PaCO2 were reduced. The patient was then able to tolerate periods of unassisted ventilation.

Dietary Carbohydrates↗
PubMed1987

Trauma and pulmonary insufficiency: mediators and modulators of adult respiratory distress syndrome.

Adult respiratory distress syndrome is a complex disease resulting in lung dysfunction secondary to a primary nonpulmonary catastrophic event. Many mediators are involved in the destructive chain of events occurring at the cellular level. Investigation of ARDS continues, with efforts directed toward blocking those mediators and thereby alleviating the lung damage and hypoxia once this cascade has been initiated. Even with these advances, however, current optimal therapy is directed toward reversing the primary inciting event and providing the supportive care required to survive the acute episode.

Humans↗
PubMed1986

Less-invasive cardiac output monitoring by earpiece densitometry.

Cardiac output was measured by thermodilution and ear densitometry in surgical ICU patients who had pulmonary arterial catheters. Overall comparison based on 56 sets of triplicate measurements revealed a correlation coefficient (r) of 0.76 between the two techniques. Although ear densitometry was more accurate with injection via the antecubital vein (r = 0.88) vs. more distal injection (r = 0.67), these data suggest that this technique lacks the accuracy for clinical application.

Blood Flow Velocity↗
PubMed1986

Residents' experience in the surgery of trauma.

Performance of surgery for trauma is an important part of residency training, yet what constitutes an adequate exposure to trauma surgery is ill defined. A retrospective review of records at a metropolitan receiving hospital was carried out for the academic year 1981-1982. Of the 50,902 patients treated in the Emergency Room more than one third were seen by a surgical resident. During this period 1,651 patients were admitted to General Surgery with traumatic injuries; 193 (12%) required intensive care. Two hundred twenty-seven major operations were performed by the General Surgical Service. For each patient operated on, 56 were seen in the Emergency Room and six required admission for nonoperative care of their injuries. Furthermore, less than 50% of patients admitted to the I.C.U. required surgery. An adequate education in trauma must be based on a large experience in the nonoperative resuscitation, diagnosis, and treatment of trauma victims. Nevertheless, the number of cases performed as operating surgeon provides a useful means of evaluation experience in trauma. Thirty cases are suggested as an appropriate level of exposure to the surgery of trauma, yet only one third of applicants to the American Board of Surgery attained this level.

Boston↗
PubMed1985

Prolonged disruption of plasma beta-endorphin dynamics following surgery.

The purpose of the present study was to examine the effects of surgery on plasma beta-endorphin dynamics. Plasma beta-endorphin levels were measured by liquid chromatography/radioimmunoassay in seven patients undergoing elective surgery. Blood samples were obtained every 4 hr for two 24-hr periods: one beginning 48 hr before surgery and the other beginning 48 hr after surgery. Computer analysis of beta-endorphin levels as a function of clock time demonstrated a true circadian rhythm preoperatively with a mean of 28.0 +/- 5.9 pg/ml. In the postoperative period mean beta-endorphin levels were significantly elevated (85.6 +/- 20.7 pg/ml, P less than 0.005). Surgical procedures caused significant phase shifting in the grouped mean circadian rhythm of plasma beta-endorphin (mean = 2.4 hr). When the data was analyzed individually, plasma circadian rhythms were found to be totally abolished in the three patients with the longest operative times (mean = 3.8 hr) and significantly displaced in time in the remaining four patients. These prolonged alterations in plasma endogenous opioid peptide levels following surgery have not been previously reported, and should be considered in the management of the postsurgical patient.

Adult↗
PubMed1985

Beta-endorphin, cortisol and postoperative delirium: a preliminary report.

A transient delirium, including hallucinations and disorientation, occurred at some time during a 48 to 72 hr postoperative period in patients recovering from elective surgery in an intensive care unit. The occurrence of delirium in these patients was associated with a significant and unusually prolonged postoperative increase in circulating levels of beta-endorphin (B-endorphin) and cortisol, and a total disruption of normal plasma circadian rhythms of B-endorphin and cortisol. Postoperative mean 24-hr plasma levels of B-endorphin and cortisol were not significantly different from preoperative baseline levels in those patients who did not exhibit post-surgical delirium. Circadian rhythms of B-endorphin and cortisol in the non-delirious patients also remained normal following surgery, although peak plasma concentrations were significantly phase-shifted to later in the day. A disruption in circadian rhythms of the endogenous opiate/hypothalamic-pituitary-adrenal axis may represent an important component of post-operative psychological changes that are frequently observed in the intensive care unit setting.

Adult↗
PubMed1985

Severe combined respiratory and myocardial failure treated with high-frequency ventilation.

High levels of positive end-expiratory pressure (PEEP) impair cardiac output. The subsequent lowering of mixed venous oxygenation, when coupled with a significant intrapulmonary shunt, may dramatically depress PaO2. We present a patient whose severe myocardial and respiratory insufficiency was unmanageable on conventional ventilation with high levels of PEEP and maximal inotropic support. High-frequency ventilation superimposed on conventional ventilation lowered peak airway pressure and dramatically improved both cardiac and pulmonary function.

Cardiac Output↗
PubMed1985

Effect of sample dilutions on arterial blood gas determinations.

A study was undertaken to determine the blood gas effects of incompletely purging heparinized saline flush solution from an indwelling arterial catheter and pressure tubing. Hematocrit and blood gases were measured after withdrawing 0, 2, 4, 6, 8, and 10 ml of flush-blood solutions before sampling from a 20-ga radial artery catheter and 7-ft pressure tubing and stopcock. The pH and hematocrit were nearly unchanged between purging volumes of 8 and 10 ml. The PaO2 had a 2.4% error, while the PaCO2 had a 4.4% error. Because there is no standard arterial line setup, it is recommended that each ICU undertake a similar study to determine the optimal volume of aspirated flush-blood solution before blood gas sampling, in order to achieve accurate blood gas results and minimize blood waste.

Blood Gas Analysis↗