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Biomedical subjects

S C Body

Publications and source records attributed to S C Body.

At least 19 recordsLinked to original sources
PubMed2000

Institutional variability in red blood cell conservation practices for coronary artery bypass graft surgery. Institutions of the MultiCenter Study of Perioperative Ischemia Research Group.

OBJECTIVE: To assess whether substantial institutional variability exists in red blood cell conservation practices associated with coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, randomized patient enrollment and data collection. SETTING: Twenty-four U.S. academic institutions participating in the Multicenter Study of Perioperative Ischemia. PARTICIPANTS: A well-defined subset of primary CABG surgery patients (n = 713) expected to be at low risk for bleeding and exposure to allogeneic transfusion. INTERVENTIONS: None (observational study). MEASUREMENTS AND MAIN RESULTS: Frequency of use of red blood cell conservation techniques was determined among institutions. Correlation was determined between use of each technique and transfusion of allogeneic red blood cells and between use of each technique and median institutional blood loss. Significant variability (p < 0.01) was detected in institutional transfusion practice with respect to the use of predonated autologous whole blood, normovolemic hemodilution, red cell salvage, and reinfusion of shed mediastinal blood. The frequency of institutional use of these techniques was not associated with allogeneic transfusion (r2 < 0.15) or blood loss (r2 < 0.10) in the low-risk population of patients examined. CONCLUSIONS: Institutions vary significantly in perioperative blood conservation practices for CABG surgery. Further study to determine the appropriate use of these techniques is warranted.

Blood Loss, Surgical↗
PubMed2000

Anesthetic considerations for patients with severe emphysematous lung disease.

The pathophysiology, medical and surgical management of emphysema have been reviewed as a foundation to the physiological goals and principles of anesthetic management of patients with emphysema. An understanding of the cardiovascular and respiratory consequences of emphysema combined with anesthesia, PPV, and thoracic surgery is essential to achieving the challenging physiological goals of providing anesthesia, positive pressure and one-lung ventilation, and postoperative analgesia in a manner consistent with rapid postoperative extubation, hemodynamic stability, adequate gas exchange, and minimal barotrauma for this population of patients.

Anesthesia↗
PubMed1999

Safety and efficacy of shed mediastinal blood transfusion after cardiac surgery: a multicenter observational study. Multicenter Study of Perioperative Ischemia Research Group.

OBJECTIVE: To examine the efficacy and safety of shed mediastinal blood (SMB) transfusion in preventing allogenic red blood cell (RBC) transfusion. DESIGN: An observational clinical study. SETTING: Twelve US academic medical centers. PARTICIPANTS: Six hundred seventeen patients undergoing elective primary coronary artery bypass grafting. INTERVENTIONS: Patients were administered SMB transfusion or not, according to institutional and individual practice, without random assignment. MEASUREMENTS AND RESULTS: The independent effect of SMB transfusion on postoperative RBC transfusion was examined by multivariable modeling. Potential complications of SMB transfusion, such as bleeding and infection, were examined. Three hundred twelve of the study patients (51%) received postoperative SMB transfusion (mean volume, 554 +/- 359 mL). Patients transfused with SMB had significantly lower volumes of RBC transfusion than those not receiving SMB (0.86 +/- 1.50 v 1.08 +/- 1.65 units; p < 0.05). However, multivariable analysis showed that SMB transfusion was not predictive of postoperative RBC transfusion. Demographic factors (older age, female sex), institution, and postoperative events (greater chest tube drainage, lower hemoglobin level on arrival to the intensive care unit, and use of inotropes) were significant predictors of RBC transfusion. The volume of chest tube drainage on the operative day (707 +/- 392 v 673 +/- 460 mL; p = 0.30), reoperation for hemorrhage (3.1% v2.5%; p = 0.68), and overall frequency of infection (5.8% v 6.6%; p = 0.81) were similar between patients receiving and not receiving SMB, respectively. However, in patients who did not receive allogenic RBC transfusion, there was a significantly greater frequency of wound infection in the SMB group (3.6% v0%; p = 0.02). CONCLUSION: These data suggest that SMB is ineffective as a blood conservation method and may be associated with a greater frequency of wound infection.

Aged↗
PubMed1999

Individualized feedback of volatile agent use reduces fresh gas flow rate, but fails to favorably affect agent choice.

BACKGROUND: Cost reduction has become an important fiscal aim of many hospitals and anesthetic departments, despite its inherent limitations. Volatile anesthetic agents are some of the few drugs that are amenable to such treatment because fresh gas flow rate (FGFR) can be independent of patient volatile anesthetic agent requirement. METHODS: FGFR and drug use were recorded at the temporal midpoint of 2,031 general anesthetics during a 2-month preintervention period. Staff and residents were provided with their preintervention individual mean FGFR, their peer group mean, and educational material regarding volatile agent costs and low-flow anesthesia. FGFR and drug use were remeasured over a 2-month period (postintervention) immediately after this information (N = 2,242) and again 5 months later (delayed follow-up), for a further 2-month period (N = 2,056). RESULTS: For all cases, FGFR decreased from 2.4+/-1.1 to 1.8+/-1.0 l/min (26% reduction) after the intervention and increased to 1.9+/-1.1 l/min (5% increase of preintervention FGFR) at the time of delayed follow-up. Use of more expensive volatile agents (desflurane and sevoflurane) increased during the study period (P < 0.01). In a subgroup of 44 staff members with more than five cases in all study periods, 42 members decreased their mean FGFR after intervention. At delayed follow-up, 30 members had increased their FGFR above postintervention FGFR but below their initial FGFR. After accounting for other predictors of FGFR, the effectiveness of the intervention was significantly reduced at follow-up (28% reduction), but retained a significant effect compared to preintervention FGFR (19% reduction). CONCLUSIONS: Although individual feedback and education regarding volatile agent use was effective at reducing FGFR, effectiveness was reduced without continued feedback. Use of more expensive volatile agents was not reduced by education regarding drug cost, and actually increased.

Anesthesia, Inhalation↗
PubMed1998

Relation between preoperative inspiratory lung resistance and the outcome of lung-volume-reduction surgery for emphysema.

BACKGROUND: Surgery to reduce lung volume has recently been reintroduced to alleviate dyspnea and improve exercise tolerance in selected patients with emphysema. A reliable means of identifying patients who are likely to benefit from this surgery is needed. METHODS: We measured lung resistance during inspiration, static recoil pressure at total lung capacity, static lung compliance, expiratory flow rates, and lung volumes in 29 patients with chronic obstructive lung disease before lung-volume-reduction surgery. The changes in the forced expiratory volume in one second (FEV1) six months after surgery were related to the preoperatively determined physiologic measures. A response to surgery was defined as an increase in the FEV1 of at least 0.2 liter and of at least 12 percent above base-line values. RESULTS: Of the 29 patients, 23 had some improvement in FEV1 including 15 who met the criteria for a response to surgery. Among the variables considered, only preoperative lung resistance during inspiration predicted changes in expiratory flow rates after surgery. Inspiratory lung resistance correlated significantly and inversely with improvement in FEV1 after surgery (r=-0.63, P<0.001). A preoperative criterion of an inspiratory resistance of 10 cm of water per liter per second had a sensitivity of 88 percent (14 of 16 patients) and a specificity of 92 percent (12 of 13 patients) in identifying patients who were likely to have a response to surgery. CONCLUSIONS: Preoperative lung resistance during inspiration appears to be a useful measure for selecting patients with emphysema for lung-volume-reduction surgery.

Adult↗
PubMed1998

Hematocrit value on intensive care unit entry influences the frequency of Q-wave myocardial infarction after coronary artery bypass grafting. The Institutions of the Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

OBJECTIVES: No data exist regarding "the best" hematocrit value after coronary artery bypass graft surgery. Transfusion practice varies, because neither an optimal hematocrit value nor a uniform transfusion trigger criterion has been determined. METHODS: To investigate the optimal hematocrit value, we studied 2202 patients undergoing coronary bypass. The hematocrit value on entry into the intensive care unit (IHCT) was categorized into three groups: high (> or = 34%), medium (25% to 33%), and low (< or = 24%). Characteristics and adverse events (outcomes) were compared, and the effect of IHCT on the risk of myocardial infarction was determined by logistic regression. RESULTS: High IHCT (> or = 34%) was associated with an increased rate of myocardial infarction (8.3% vs 5.5% vs 3.6%; p < or = 0.03, high, medium vs low) and with more severe left ventricular dysfunction (11.7% vs 7.4% and 5.7%; p=0.006, high, medium vs low). Mortality rate increased with higher IHCT when all the high-risk subgroups were combined (8.6% vs 4.5% vs 3.2%; p < 0.001, high, medium vs low). By multivariate analysis, IHCT remained the most significant predictor of adverse outcomes (relative risk high vs low 2.22, 95% confidence interval: 1.04 to 4.76). No characteristic, event, medication, or transfusion therapy confounded the relationship between IHCT and outcome. CONCLUSION: High IHCT is associated with a higher rate of myocardial infarction and is an independent predictor of infarction. On the basis of the risk of myocardial infarction, there is no rationale for transfusion to an arbitrary level after coronary artery bypass grafting.

Anemia↗
PubMed1998

Variability in transfusion practice for coronary artery bypass surgery persists despite national consensus guidelines: a 24-institution study. Institutions of the Multicenter Study of Perioperative Ischemia Research Group.

BACKGROUND: An estimated 20% of allogeneic blood transfusions in the United States are associated with cardiac surgery. National consensus guidelines for allogeneic transfusion associated with coronary artery bypass graft (CABG) surgery have existed since the mid- to late 1980s. The appropriateness and uniformity of institutional transfusion practice was questioned in 1991. An assessment of current transfusion practice patterns was warranted. METHODS: The Multicenter Study of Perioperative Ischemia database consists of comprehensive information on the course of surgery in 2,417 randomly selected patients undergoing CABG surgery at 24 institutions. A subset of 713 patients expected to be at low risk for transfusion was examined. Allogeneic transfusion was evaluated across institutions. Institution as an independent risk factor for allogeneic transfusion was determined in a multivariable model. RESULTS: Significant variability in institutional transfusion practice was observed for allogeneic packed red blood cells (PRBCs) (27-92% of patients transfused) and hemostatic blood components (platelets, 0-36%; fresh frozen plasma, 0-36%; cryoprecipitate, 0-17% of patients transfused). For patients at institutions with liberal rather than conservative transfusion practice, the odds ratio for transfusion of PRBCs was 6.5 (95% confidence interval [CI], 3.8-10.8) and for hemostatic blood components it was 2 (95% CI, 1.2-3.4). Institution was an independent determinant of transfusion risk associated with CABG surgery. CONCLUSIONS: Institutions continue to vary significantly in their transfusion practices for CABG surgery. A more rational and conservative approach to transfusion practice at the institutional level is warranted.

Blood Component Transfusion↗
PubMed1998

The concordance of intraoperative left ventricular wall-motion abnormalities and electrocardiographic S-T segment changes: association with outcome after coronary revascularization. Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

BACKGROUND: Transesophageal echocardiography (TEE) and Holter electrocardiography (ECG) are used to detect intraoperative ischemia during coronary artery bypass graft surgery (CABG). Concordance of these modalities and sensitivity as indicators of adverse perioperative cardiac outcomes are poorly defined. The authors tried to determine whether routine use of Holter ECG and TEE in patients with CABGs has clinical value in identifying those patients in whom myocardial infarction (MI) is likely to develop. METHODS: A total of 351 patients with CABG and both ECG- and TEE-evaluable data were examined for the occurrence of ischemia and infarction. The TEE and five-lead Holter ECGs were performed continuously during cardiac surgery. The incidence of MI (creatine kinase-MB > or = 100 ng/ml) within 12 h of arrival in the intensive care [ICU] unit, new ECG Q wave on ICU admission or on the morning of postoperative day 1, or both, were recorded. RESULTS: Electrocardiographic or TEE evidence of intraoperative ischemia was present in 126 (36%) patients. The concordance between modalities was poor (positive concordance = 17%; Kappa statistic = 0.13). Myocardial infarction occurred in 62 (17%) patients, and 32 (52%) of them had previous intraoperative ischemia. Of these, 28 (88%) were identified by TEE, whereas 13 (41%) were identified by ECG. Prediction of MI was greater for TEE compared with ECG. CONCLUSIONS: Wall-motion abnormalities detected by TEE are more common than S-T segment changes detected by ECG, and concordance between the two modalities is low. One half of patients with MI had preceding ECG or TEE ischemia. Logistic regression revealed that TEE is twice as predictive as ECG in identifying patients who have MI.

Aged↗
PubMed1997

Influence of inhaled nitric oxide on systemic flow and ventricular filling pressure in patients receiving mechanical circulatory assistance.

BACKGROUND: In patients with left ventricular (LV) dysfunction, inhaled nitric oxide (NO) decreases pulmonary vascular resistance (PVR) but causes a potentially clinically significant increase in left atrial pressure (LAP). This has led to the suggestion that inhaled NO may reach the coronary circulation and have a negative inotropic effect. This study tested an alternative hypothesis that LAP increases because of volume shifts to the pulmonary venous compartment caused by NO-induced selective pulmonary vasodilation. METHODS AND RESULTS: The Thermo Cardiosystems Heartmate is an LV assist device (LVAD) that can be set (by controlling pump rate) to deliver fixed or variable systemic blood flow. Eight patients (between 1 and 11 days after LVAD implantation) were administered inhaled NO (20 and 40 ppm for 10 minutes), and LAP, systemic flow, and pulmonary arterial pressure were measured in both fixed and variable pump flow modes. In both modes, inhaled NO lowered PVR (by 25 +/- 6% in the fixed mode, P < .001, and by 21 +/- 5% in the variable mode, P < .003). With fixed pump flow, LAP rose from 12.5 +/- 1.2 to 15.1 +/- 1.4 mm Hg (P < .008). In the variable flow mode, LAP did not increase and the assist device output rose from 5.3 +/- 0.3 to 5.7 +/- 0.3 L/min (P < .008). CONCLUSIONS: A selective reduction in PVR by inhaled NO can increase LAP if systemic flow cannot increase. These data support the hypothesis that with LV failure, inhaled NO increases LAP by increasing pulmonary venous volume and demonstrate that inhaled NO has beneficial hemodynamic effects in LVAD patients.

Administration, Inhalation↗
PubMed1997

Manufacture and measurement of nitrogen oxides.

A decade of research has identified nitric oxide as a unique endogenous biologic mediator with functions as diverse as vasodilation, macrophage cytotoxicity, platelet adhesion, and memory formation. Measurement devices, previously used in research on atmospheric nitrogen oxides, are being adapted for and applied to clinical situations without approval, regulation, or rigorous testing, and with little understanding of how the devices work or their limitations. This article discusses the chemistry, manufacture, and measurement of nitrogen oxides.

Administration, Inhalation↗
PubMed1996

Laryngeal mask airway for therapeutic fiberoptic bronchoscopic procedures.

These cases illustrate the advantages of the laryngeal mask as compared with an endotracheal tube or oxygen face mask for selected patients undergoing therapeutic bronchoscopic procedures. The advantages include a larger internal diameter allowing easier passage of instruments, reduced work of breathing, lack of discomfort associated with insertion, access to the vocal cords and upper trachea unimpeded by the presence of an endotracheal tube, and capnographic and volume monitoring of respiration. The LMA is thus a valuable alternative for airway management in pulmonary compromised patients undergoing therapeutic bronchoscopic procedures.

Adult↗
PubMed1996

Pulmonary function changes during epidural anesthesia for cesarean delivery.

Although changes in pulmonary function in parturients are documented, little is known about effects of regional anesthesia on these changes. This study was undertaken to determine if two local anesthetics, often used for epidural anesthesia for cesarean delivery, have different effects on pulmonary function testing. Nineteen ASA physical status I parturients undergoing elective cesarean delivery with epidural anesthesia were randomly assigned in double-blind fashion to receive either 0.5% bupivacaine or 2% lidocaine with epinephrine (1/200,000). Pulmonary function tests were measured using a calibrated spirometer with computer-recorded flow volume loops. Peak inspiratory pressure and peak inspiratory flow rate, peak expiratory pressure (PEP) and peak expiratory flow rate, forced vital capacity (FVC), and forced expiratory volume in 1 s (FEV1) were measured. Measurements were taken prior to epidural placement and at T-10 and T-4 levels. Peak inspiratory pressure, FEV1/FVC, FEV1, FVC, peak expiratory flow rate, and peak inspiratory flow rate did not differ from baseline in either group. Patients receiving lidocaine showed a significantly greater decrease in PEP at both T-10 and T-4 levels. Pep is largely dependent on abdominal musculature. If a denser motor block is provided by 2% lidocaine with epinephrine than by 0.5% bupivacaine, these muscles would be more affected, resulting in a greater decrease in PEP. These results may have implications regarding choice of local anesthetic for epidural anesthesia in parturients with some degree of respiratory compromise undergoing cesarean delivery.

Adult↗
PubMed1996

Multicenter study of target-controlled infusion of propofol-sufentanil or sufentanil-midazolam for coronary artery bypass graft surgery. Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

BACKGROUND: The use of target-controlled infusions of anesthetics for coronary artery bypass graft surgery has not been studied in detail. The effects of target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were evaluated and compared. METHODS: At 14 clinical sites, 329 patients were given a target-controlled infusion of propofol (n = 165) to produce effect-site concentration (Ce) of > or = 3-micrograms/ml or a target-controlled infusion of sufentanil (n = 164). Sufentanil or midazolam, respectively, also were infused. Systolic hypertension, hypotension, tachycardia, and bradycardia were assessed by measuring heart rate and blood pressure every minute during operation. Myocardial ischemia was assessed perioperatively by monitoring ST segment deviation via continuous three-lead Holter electrocardiography, and it was evaluated during operation by monitoring left ventricular wall motion abnormality via transesophageal echocardiography. RESULTS: The measured cardiovascular parameters were satisfactory and usually similar for the patients receiving propofol-sufentanil or sufentanil-midazolam. The primary endpoint of the percentage of patients with intraoperative ST segment deviation (23 +/- 6% vs. 24 +/- 6%, P = 0.86) did not differ significantly between the two groups. The incidence of left ventricular wall motion abnormality shown on transesophageal echocardiography before (19 +/- 4% vs. 26 +/- 4%, P = 0.25) and after (23 +/- 4% vs. 31 +/- 5%, P = 0.32) cardiopulmonary bypass also did not differ significantly for the two groups. Changes in intraoperative target concentration were more frequent with propofol-sufentanil anesthetic than with sufentanil-midazolam (11.7 +/- 7.1 vs. 7.3 +/- 3.6, P < 0.001). The incidence of intraoperative hypotension (77% vs. 55%, P < 0.001), the use of inotropic/vasopressor medications (93% vs. 84%, P = 0.01), and the administration of crystalloids (2.8 +/- 1.4 L vs. 2.4 +/- 1.2 L, P < 0.001) were significantly greater in the propofol-sufentanil group. Conversely, the incidence of intraoperative hypertension (43% vs. 54%, P = 0.05) and the use of antihypertensive/vasodilator medications (70% vs. 90%, P < 0.001) were significantly less in the propofol-sufentanil group. CONCLUSIONS: Target-controlled infusions of propofol or sufentanil, supplemented by infusions of sufentanil or midazolam, respectively, were suitable to provide anesthesia for coronary artery bypass graft surgery. Continuous monitoring revealed a high prevalence of hemodynamic abnormalities. Despite greater hypotension in the propofol-sufentanil group and greater hypertension in the sufentanil-midazolam group, episodes of myocardial ischemia were similar for both groups and were not temporally related to episodes of hemodynamic abnormalities.

Aged↗