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Biomedical subjects

B Szekely

Publications and source records attributed to B Szekely.

At least 19 recordsLinked to original sources
PubMed2006

Anticoagulation monitoring during vascular surgery: accuracy of the Hemochron low range activated clotting time (ACT-LR).

BACKGROUND: Activated clotting time (ACT) is currently used to monitor high concentrations of heparin anticoagulation. A new instrument, the Hemochron Jr Signature device, has been specifically designed to measure ACT in low-range heparin plasma concentrations (ACT-LR). The purpose of this study was to compare ACT-LR with anti-Xa activity in patients receiving low-dose i.v. heparin during vascular surgery. METHODS: Thirty patients, undergoing arterial vascular surgery, were included in the study and received unfractionated heparin (initial dose 50 u kg(-1)). One hundred and thirty-two pairs of blood samples were simultaneously collected during surgery to determine ACT-LR and anti-Xa activity. Pearson correlation, Kappa test, ROC curve and a specific clinical interpretation of the correlation were performed. RESULTS: ACT-LR ranged from 68 to 380 s, anti-Xa activity from 0 to 1.45 u ml(-1). We observed a strong correlation between anti-Xa activity and ACT-LR (r(2)=0.87; P<0.0001). Accuracy of ACT-LR was good for anti-Xa activity up to 0.6 u ml(-1) (Kappa, 0.94; accuracy, 97%) and 0.8 u ml(-1) (Kappa, 0.79; accuracy, 90%), and poor for anti-Xa activity above 1 u ml(-1) (Kappa, 0.59). A clinical interpretation of the correlation graph found 98% of measured ACT-LR values to be accurate. CONCLUSION: Hemochron Jr Signature provides measurements of ACT-LR, which are accurate for monitoring heparin anticoagulation at anti-Xa activity below 0.8 u ml(-1).

Adult↗
PubMed2006

Evaluation of the pharmacokinetic profile and analgesic efficacy of oral morphine after total hip arthroplasty.

BACKGROUND AND OBJECTIVE: Oral morphine may be useful for postoperative pain relief, but few studies have tested its use after in-hospital surgery. METHODS: We evaluated clinical efficacy and the pharmacokinetic parameters of oral morphine after total hip arthroplasty. We recruited 60 patients who had total hip arthroplasty under general anaesthesia. The patients were randomized to receive placebo, 10 mg morphine sulphate or 20 mg morphine sulphate orally every 4 h for 24 h. The oral administration was started 3 h after the morphine-loading dose in the Post Anaesthesia Care Unit and then patients used intravenous morphine patient-controlled analgesia for 24 h. Pain score at rest (scored by patients on a visual analogue scale), sedation, nausea, vomiting and urinary retention were monitored. In 11 additional total hip arthroplasty patients, we determined the pharmacokinetics of morphine and its metabolites after oral administration of 20 mg morphine sulphate every 4 h for 16 h. RESULTS: The amount of morphine administered via patient-controlled analgesia over 24 h was reduced in the 20-mg group compared with that in the placebo group (19.0 +/- 2.7 mg vs. 33.0 +/- 5.5 mg; P = 0.03). No significant morphine-sparing effect was observed in the 10-mg group. Pain scores and side-effects were similar in all groups. The pharmacokinetic study revealed a limited and slow absorption of morphine. CONCLUSION: Despite a limited absorption of oral morphine postoperatively, high doses of oral morphine have a significant analgesic effect after total hip arthroplasty.

Administration, Oral↗
PubMed2002

Value of bispectral index monitoring during cardiopulmonary resuscitation.

A 67-yr-old man, undergoing pulmonary metastasis resection, experienced a postoperative cardiopulmonary arrest as a result of severe bleeding. Cardiopulmonary resuscitation (CPR) was initiated, then bispectral index (BIS) monitoring was used which reassured the medical team of the adequacy of the resuscitation.

Aged↗
PubMed2001

Increased CD8(+) T cells associated with Chlamydia pneumoniae in symptomatic carotid plaque.

BACKGROUND AND PURPOSE: The presence of Chlamydia pneumoniae has been reported in carotid atheroma, but its causative effect in the activation of an atherosclerotic plaque to a prothrombotic state remains unproved. Antigen- mediated activation of T lymphocytes within plaque may represent a mechanism by which infection can result in plaque conversion. The goal of the present study was to characterize the T-cell subtype profile related to the presence of C pneumoniae in patients with symptomatic versus asymptomatic carotid atherosclerosis. METHODS: We studied 14 plaques (5 symptomatic and 9 asymptomatic) positive for C pneumoniae confirmed by polymerase chain reaction and 14 plaques (6 symptomatic and 8 asymptomatic) from age- and stenosis-matched patients negative for C pneumoniae by polymerase chain reaction. T-cell subpopulations of T-helper, T-cytotoxic, and T-memory lymphocytes were identified through indirect enzyme immunohistochemistry with anti-CD3+, anti-CD4+, anti-CD8+, and anti-CD45RO+ monoclonal antibodies, respectively. Results are expressed as the number of positive cells per millimeter squared. RESULTS: In the absence of C pneumoniae, symptomatic plaques had a modest but significant increase of CD3+ (89.6 versus 55.3, P=0.013), CD4+ (57.3 versus 32.7, P=0.01), and CD45RO+ (82.8 versus 43.7, P=0.007), but not CD8+ T cells (28.5 versus 25.5, P=0.245) compared with asymptomatic. However, in the presence of C pneumoniae, there was significant increase of all T-lymphocyte subtypes in symptomatic plaques, including CD8+ (76.8 versus 30.3, P=0.03), CD3+ (192.1 versus 80.4, P=0.004), CD4+ (111.9 versus 37.9, P=0.003), and CD45RO+ (120.2 versus 72.9, P=0.003) cells compared with asymptomatic plaques. With use of 2-way ANOVA, both the presence of chlamydia and symptoms were associated with significantly higher T-cell counts (P<0.005 for all subtypes). CONCLUSIONS: Although all patients with symptomatic disease show a modest elevation in the concentration of intraplaque lymphocytes, a preferential increase in CD8+ class I-restricted T cells is observed in symptomatic carotid plaque positive for C pneumoniae. These data provide incentive to further explore the role of Chlamydia in the modification of immune-mediated mechanisms in active atherosclerotic plaque.

Aged↗
PubMed2000

Assessment of systematic use of intraoperative transesophageal echocardiography during cardiac surgery in adults: a prospective study of 203 patients.

OBJECTIVE: To determine the usefulness of systematic intraoperative transesophageal echocardiography in a cardiac surgical unit. DESIGN: Open prospective observational survey. SETTING: University Hospital. PARTICIPANTS: Consecutive adult patients (n = 203) undergoing elective or urgent cardiac operations. MEASUREMENTS AND MAIN RESULTS: Pre-cardiopulmonary bypass imaging yielded unsuspected findings in 26 patients (12.8%) and changed the planned surgery in 22 patients (10.8%). Transesophageal echocardiography modified the diagnosis in eight patients (17%) operated on for mitral valvulopathy, in seven patients (15.5%) with aortic valvular disease, in four patients (4.6%) with coronary artery disease, in five patients operated on for thoracic aorta diseases regardless of their localization (18.5%), and in two miscellaneous cases. On the basis of the data obtained from the transesophageal echocardiography carried out at the end of cardiopulmonary bypass, an immediate reintervention was required in five cases (2.5%). CONCLUSIONS: It is concluded that systematic intraoperative transesophageal echocardiography significantly affected decision making in this cardiac surgical unit. Its routine use in all cardiac surgical patients is recommended.

Adult↗
PubMed1994

Effects of propofol and thiopental on coronary blood flow and myocardial performance in an isolated rabbit heart.

BACKGROUND: Some clinical and experimental studies suggest that propofol decreases myocardial contractility and relaxation, whereas others report preserved cardiac function. To investigate the effects of propofol on intrinsic contractility and relaxation, increasing concentrations of propofol were infused in isolated blood-perfused rabbit hearts. Equimolar concentrations of thiopental were infused as a reference group. METHODS: Coronary blood flow, left ventricular contractility and relaxation (as maximal positive and negative left ventricular pressure derivatives [dP/dtmax and dP/dtmin], respectively), and myocardial oxygen consumption (MvO2) were measured during infusion of 10-1,000 microM propofol in blood-perfused hearts. To determine whether the effects of propofol depend on the heart's perfusate, propofol also was infused in isolated buffer-perfused rabbit hearts. In addition, the effects of propofol solvent were investigated in blood- and buffer-perfused preparations. RESULTS: In blood-perfused preparations, coronary blood flow increased with propofol concentrations greater than 30 microM and with 300 and 1,000 microM thiopental. Left ventricular dP/dtmax and dP/dtmin remained unchanged with propofol and decreased with concentrations of thiopental equal to or greater than 30 microM. MvO2 increased with 1,000 microM propofol, whereas coronary venous oxygen tension and content remained unchanged. MvO2 decreased with thiopental associated with a significant increase in coronary venous oxygen tension and content. In six buffer-perfused hearts, basal coronary blood flow was much greater and MvO2 less than in blood-perfused hearts. Left ventricular dP/dtmax and dP/dtmin decreased with 30, 100, and 300 microM propofol. Propofol vehicle did not change coronary blood flow, myocardial performance, or MvO2 of blood- or buffer-perfused hearts. CONCLUSIONS: When compared to a reference drug such as thiopental, propofol did not depress the myocardial performance of blood-perfused rabbit hearts. The type of the perfusate (blood vs. buffer), however, had a major influence on the myocardial effects of propofol.

Animals↗
PubMed1992

Activated macrophages depress the contractility of rabbit carotids via an L-arginine/nitric oxide-dependent effector mechanism. Connection with amplified cytokine release.

Inflammatory mediators released by macrophages (M phi) are believed to be involved in septic vasoplegia. To investigate the effect of M phi on vascular reactivity, excised rabbit carotids were exposed intraluminally either to peritoneal rabbit M phi, activated by 18 h of incubation with 1 microgram/ml lipopolysaccharide, or to the supernatants (SPN) derived from them. The contractile responses to phenylephrine (PE, 10(-6) M) were determined by measuring changes in diameter using an ultrasonic microdimensiometer 1, 2, and 3 h after the first control contraction. In control arteries (n = 12), PE-induced contractions were, respectively, 102.9 +/- 3.3%, 95.2 +/- 4.1%, and 89.7 +/- 3.8% of the first contraction, after 1, 2, and 3 h. Activated M phi significantly reduced PE-stimulated contractions after as little as 1 h of carotid exposure (percentage of controls at 1, 2, or 3 h: 74.1 +/- 5.6, 57.2 +/- 5.2, and 34.2 +/- 5.6, n = 10, P less than 0.001). The activated macrophage-derived SPN took longer to diminish carotid contractility than the M phi themselves, and became significant only after 2 h. The greater effect of M phi might be due to cooperation between M phi and vascular cells, as suggested by the amplified interleukin-1 release observed after M phi infusion. The presence of the endothelium partially protected carotid contractility from depression by activated M phi. Extraluminal addition of NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthesis prevented this depression in arteries with or without endothelium. No products of the oxidative pathway of L-arginine were detected in rabbit activated M phi. These results suggest that activation of this pathway in smooth muscle cells seems to be involved in vascular hypocontractility.

Animals↗
PubMed1990

Aortic surgery: effect of clonidine on intraoperative catecholaminergic and circulatory stability.

Twenty-eight patients presenting for aortic surgery were randomly assigned in a double-blind, placebo-controlled protocol to receive placebo (n = 14) or clonidine (4.7 +/- 1.2 micrograms.kg-1 po; n = 14), in addition to flunitrazepam 120 min before induction of anesthesia. Plasma catecholamines (CA) and hemodynamic variables were determined at 7 stages during surgery. In the placebo group, plasma epinephrine (E) and norepinephrine (NE) had risen twofold at skin closure compared to baseline (E: from 109 +/- 51 pg.ml-1 to 294 +/- 161 pg.ml-1; NE: from 658 +/- 226 to 1150 +/- 494 pg.ml-1). Plasma CA were significantly lower in the clonidine group (P less than 0.001 and 0.01 vs placebo for NE and E respectively). In both groups, similar directional changes were observed for the circulatory variables, upon aortic clamping and declamping. In the clonidine group, however, mean arterial pressure was lower at most stages (P less than 0.05 vs placebo); moreover, stroke volume index was greater in the clonidine group (P less than 0.05) upon declamping. This improved stability in the clonidine group was achieved with a halving in the number of anesthetic/circulatory interventions (P less than 0.05 vs placebo). Provided intravascular volume is adequate, clonidine suppresses the increase in plasma catecholamines induced by aortic surgery and improves circulatory stability, with a reduced number of anesthetic, circulatory adjustments.

Adult↗
PubMed1989

Baroreceptor control after cervical epidural anesthesia in patients undergoing carotid artery surgery.

Baroreceptor (BR) reactivity was studied in 16 patients scheduled for carotid artery surgery performed under cervical epidural anesthesia with 0.375% bupivacaine (15 mL). In the first seven patients, BR reactivity was assessed by measurement of the slopes of the linear relationship between systolic arterial pressure (SAP) and the RR interval on the electrocardiogram. Alterations of blood pressure (BP) were produced using sequential intravenous (IV) doses of nitroglycerin (NTG; 100 to 200 micrograms) or phenylephrine (PHE; 100 to 200 micrograms), before and 30 minutes after epidural anesthesia. The changes in SAP and heart rate (HR) determined during the four phases of a Valsalva maneuver were evaluated in a second set of measurements before and after cervical epidural blockade. In nine additional patients, a third set of measurements studying BR reactivity after carotid clamping and unclamping was performed in order to assess the effect of carotid handling on BP control. Cervical epidural anesthesia induced moderate decreases in BP (SAP, 150 +/- 18 mmHg before cervical block, 143 +/- 27 mmHg after cervical block, P less than 0.05) and HR (RR, 812 +/- 120 ms before cervical block, 938 +/- 130 ms after cervical block, P less than 0.05). Cervical epidural anesthesia depressed BR reactivity during deactivation as assessed by the decrease in the BR slope after PHE injection (6.6 +/- 4.4 ms/mmHg before cervical block v 2.5 +/- 1.8 ms/mmHg after cervical block, P less than 0.01) and activation as assessed by the changes in SAP and HR during phases II and IV of the Valsalva maneuver.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

[Carotid endarterectomy under cervical epidural anesthesia. Analysis of neurologic manifestations].

Carotid endarterectomy can be complicated by neurological events due to different mechanisms. Monitoring cerebral function is difficult under general anaesthesia. By contrast, the monitoring of awareness and neurological deficit is very easy under regional anaesthesia. The aim of this study was to assess the requirement for arterial shunting during endarterectomy performed under cervical epidural anaesthesia, to analyse the neurological events and to compare the value of clinical and electroencephalographic monitoring. Sixty-four patients were included in this study. Cervical epidural anesthesia was performed with 0.375% bupivacaine and 100-150 micrograms fentanyl. In 19 high risk patients, a one-channel electroencephalographic filter processor (Cerebral function monitor, Critikon) was placed over the affected hemisphere. Before surgery, it was estimated, on angiographic and Doppler data, that 18 patients needed an arterial shunt for carotid clamping. An arterial shunt was in fact inserted during surgery in only four patients, because of cerebral ischaemia after carotid clamping. Transient obnubilation was observed during carotid clamping in three other patients; it disappeared on unclamping in two, and on increasing blood pressure in the third. An additional patient suffered from a very short loss of awareness after declamping, due to cerebral embolism. The cerebral function monitor never documented false positive results, but failed to detect one out of every five neurological events. Controlateral carotid occlusion and preoperative stroke were documented to correlate with peroperative neurological events. Cervical epidural anaesthesia, which maintains consciousness during surgery, reduced in high-risk patients the need for arterial shunting as well as that for the analysis of neurological events.

Aged↗
PubMed1986

Insulin-induced factitious hypoglycemic coma.

Hypoglycemia due to the ingestion of oral hypoglycemic agents or injection of insulin is a common way for chronic factitious disorder to present to physicians. Despite this fact, factitious hypoglycemic coma is rare. Because hypoglycemia is potentially fatal, with numerous sequelae, physicians need to be aware of its occurrence and method of detection. A case of chronic factitious disorder presenting as hypoglycemic coma is presented and its implications discussed.

Adult↗