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Biomedical subjects

T W Latson

Publications and source records attributed to T W Latson.

24 records · Page 2Linked to original sources
PubMed1982

Functional significance of coronary collateral vessels in patients with coronary artery disease.

Regional myocardial perfusion was measured in 12 normal subjects and in 34 patients with coronary artery disease (CAD) at rest and during infusion of isoproterenol. Increments in regional flows normalized for change in heart rate-systolic product were 91 +/- 28% (S.D.) in normals, 71 +/- 44% in normal regions in diseased hearts, 58 +/- 33% in regions supplied by 50% to 70% stenosed arteries, 35 +/- 32% in regions supplied by arteries stenosed by more than 70%, and 16 +/- 27% in regions supplied by collateral vessels only. In 3 of 14 regions perfused entirely via collateral pathways, regional perfusion decreased with isoproterenol. Therefore the extent to which coronary flow reserve estimated with isoproterenol was compromised varied directly with the severity of anatomic coronary artery lesions and, in some regions entirely perfused by collateral vessels, an increase in heart rate-systolic pressure product was accompanied by a decrease in perfusion below resting levels. It is concluded that collateral vessels effectively maintain flow rates at normal levels at rest but tend to be inefficient at delivering blood when myocardial oxygen demand is increased.

Blood Pressure↗
PubMedDate not supplied

Effects of three anesthetic induction techniques on heart rate variability.

STUDY OBJECTIVE: To investigate the effects of different clinical induction techniques on heart rate variability (HRV). DESIGN: Two studies are reported. Study 1 prospectively compared the effects of two induction techniques (etomidate vs. thiopental sodium) known to have widely disparate effects on cardiovascular reflexes. Study 2 specifically investigated whether the vagotonic effects of sufentanil cause an increase in vagally mediated HRV. SETTING: Elective surgery in a university-affiliated hospital. PATIENTS: Study 1: 18 ASA physical status I patients having minor surgery; Study 2: 10 ASA physical status III and IV patients having cardiac surgery. INTERVENTIONS: In Study 1, anesthesia was induced with either etomidate 0.3 mg/kg or thiopental sodium 4 mg/kg with 60% nitrous oxide in oxygen. In Study 2, anesthesia was induced with a sufentanil infusion (total dose 2.9 +/- 0.2 micrograms/kg). MEASUREMENTS AND MAIN RESULTS: The electrocardiogram-derived heart rate signal was subjected to power spectral analysis (similar to electroencephalographic analysis) to obtain measurements of (1) absolute HRV power [units of (beats per minute)2] within defined frequency ranges (HRVLO = power between 0 and 0.125 Hz; HRVHI = power between 0.126 and 0.5 Hz; HRVTOT = HRVLO + HRVHI) and (2) normalized HRV power (the percentage of total power) within these same frequency ranges [e.g., %HRVHI = (HRVHI/HRVTOT) x 100%]. In Study 1, both techniques caused large reductions in HRVTOT. The reduction caused by the thiopental sodium technique (-89% +/- 2%) significantly exceeded that caused by the etomidate technique (-58% +/- 13%, p less than 0.02). In Study 2, sufentanil decreased absolute power measurements of vagally mediated HRV (-69 +/- 12 change in HRVHI) but increased corresponding normalized measurements of vagally mediated HRV (90% +/- 30% increase in %HRVHI). CONCLUSIONS: In Study 1, the greater reduction in HRV with the thiopental sodium technique provides evidence that the depressant effects of anesthetics on HRV are related in part to their effects on cardiovascular reflexes. However, the significant depression in HRV caused by the etomidate technique suggests that mechanisms other than baroreflex depression (e.g., impaired consciousness) also are important in these depressant effects. In Study 2, the decrease in HRVHI caused by sufentanil documents that absolute power measurements of vagally mediated HRV are not correlated with changes in parasympathetic tone during a potent opioid induction. This lack of a correlation may result from the decrease in total HRV observed with loss of consciousness. The increase in %HRVHI suggests that normalized measurements of HRV may still provide an index of changes in sympathetic-parasympathetic balance, even when total HRV is decreased following anesthetic administration.

Adolescent↗
PubMedDate not supplied

Influence of ketorolac tromethamine on clot elastic strength in humans as assessed by thromboelastography.

STUDY OBJECTIVE: To evaluate the effect of ketorolac tromethamine on coagulation using thromboelastography (TEG). DESIGN: TEGs were performed in each patient before and after ketorolac administration. Each patient's predrug results were used as control measurements for comparison with the postdrug results. SETTING: Medical center surgical unit. PATIENTS: Twenty ASA physical status I and II patients undergoing minor elective surgery; 12 healthy volunteers. INTERVENTIONS: TEGs were performed in all subjects before and 60 minutes after the intramuscular (IM) administration of ketorolac tromethamine 60 mg. Ten surgical patients were studied in the intraoperative period, and 10 surgical patients were studied in the postoperative period. The 12 healthy volunteers did not undergo a surgical procedure. MEASUREMENTS AND MAIN RESULTS: Specific parameters assessed from the TEGs were reaction time (R time), coagulation time (RK time), clot formation rate (angle of deflection), and maximum clot strength (maximum amplitude of deflection). Ketorolac administration did not cause statistically significant changes in these parameters in any of the three groups studied. CONCLUSIONS: IM administration of ketorolac tromethamine 60 mg did not significantly alter the speed of formation or viscoelastic strength of clots as measured by TEG. These results provide additional support for prior clinical studies confirming the safety of ketorolac administration in the perioperative period.

Adult↗
PubMedDate not supplied

Administration of high-dose aprotinin during nonprimary cardiovascular surgery: case reports and review of the literature.

The perioperative management of two patients undergoing complex "redo" cardiac surgical procedures are presented. The management of both patients included the prophylactic administration of aprotinin via a "compassionate use" protocol. Aprotinin, a serine protease inhibitor, has been shown to limit the exposure to blood and blood products in patients undergoing high-risk cardiac surgical procedures. In late December 1993, the Food and Drug Administration approved aprotinin for administration to cardiac surgical patients considered at high risk for post-cardiopulmonary bypass coagulopathies. Indications for the administration of aprotinin, as well as a brief review of the literature relating to the perioperative administration of aprotinin, are included.

Adult↗