Biomedical subjects

C Sirois

Publications and source records attributed to C Sirois.

9 recordsLinked to original sources

PubMed2001

Pulmonary venous drainage into the left atrial appendage facilitates transplantation of the left lung with difficult exposure.

Heterotopic implantation of the pulmonary venous confluence into the left atrial appendage during left lung transplantation is a reasonable alternative technique to reestablish venous drainage when exposure of the native left pulmonary veno-atrial connection may be problematic. We used this approach in a 39-year-old woman with chronic bronchiectasis who underwent bilateral sequential lung transplantation through a clam-shell approach. Dense hilar scarring and a small left atrial size made exposure of the native left pulmonary veno-atrial connection difficult.

Adult↗

PubMed2000

Effect of gender, sex hormones, time variables and physiological urinary pH on apparent CYP2D6 activity as assessed by metabolic ratios of marker substrates.

The effects of gender, time variables, menstrual cycle phases, plasma sex hormone concentrations and physiologic urinary pH on CYP2D6 phenotyping were studied using two widely employed CYP2D6 probe drugs, namely dextromethorphan and metoprolol. Phenotyping on a single occasion of 150 young, healthy, drug-free women and men revealed that the dextromethorphan: dextrorphan metabolic ratio (MR) was significantly lower (P < 0.0001) in 56 female extensive metabolizers (0.008+/-0.021) compared to 86 male extensive metabolizers (0.020 +/-0.040). Urinary pH was a significant predictor of dextromethorphan: dextrorphan MRs in men and women (P < 0.001). Once-a-month phenotyping with dextromethorphan of 12 healthy young men (eight extensive metabolizers and four poor metabolizers) over a 1-year period, as well as every-other-day phenotyping with dextromethorphan of healthy, pre-menopausal women (10 extensive metabolizers and 2 poor metabolizers) during a complete menstrual cycle, did not follow a particular pattern and showed similar intrasubject variability ranging from 24.1% to 74.5% (mean 50.9%) in men and from 20.5% to 96.2% (mean 52.0%) in women, independent of the CYP2D6 phenotype (P = 0.342). Using metoprolol as a probe drug, considerable intrasubject variability (38.6+/- 12.0%) but no correlation between metoprolol: alpha-hydroxymetoprolol MRs and pre-ovulatory, ovulatory and luteal phases (mean +/- SD metoprolol: a-hydroxymetoprolol MRs: 1.086+/- 1.137 pre-ovulatory; 1.159+/-1.158 ovulatory and 1.002+/-1.405 luteal phase; P> 0.9) or 17beta-oestradiol, progesterone or testosterone plasma concentrations was observed. There was a significant inverse relationship between physiologic urinary pH and sequential dextromethorphan: dextrorphan MRs as well as metoprolol: alpha-hydroxymetoprolol MRs in men and women, with metabolic ratios varying up to six-fold with metoprolol and up to 20-fold with dextromethorphan (ANCOVA P < 0.001). We conclude that apparent CYP2D6 activity is highly variable, independent of menstrual cycle phases, sex hormones, time variables or phenotype. Up to 80% of the observed variability can be explained by variations of urinary pH within the physiological range. An apparent phenotype shift as a result of variations in urinary pH may be observed in individuals who have metabolic ratios close to the population antimode.

Administration, Oral↗

PubMed1999

Potassium concentrations and ventricular ectopy: a prospective, observational study in post-cardiac surgery patients.

OBJECTIVE: To determine whether a correlation exists between concentrations of intracellular and extracellular potassium and to determine the frequency of ventricular ectopy in patients after cardiac operations. DESIGN: Prospective, observational clinical evaluation. SETTING: Surgical-respiratory intensive care unit of a university-affiliated tertiary care center. PATIENTS: Continuous 24-hr electrocardiographic monitoring was performed, and serum (extracellular) and erythrocyte (intracellular) potassium concentrations ([K+]e and [K+]i) were determined, before cardiopulmonary bypass, immediately postoperatively, and at 2, 4, 12, and 20 hrs after elective coronary bypass grafting in 31 patients. INTERVENTIONS: None. Potassium replacement was left to the discretion of the attending physicians. MEASUREMENTS AND MAIN RESULTS: Although the mean [K+]e varied significantly during the postoperative 24-hr period (p<.0001), the [K+]i did not (p = .953). No significant correlations were found between premature ventricular beats and [K+]i, [K+]e, or [K+]i/[K+]e (all p>.05). However, among the few patients who had one or more episodes of ventricular tachycardia (VT) within 30 mins of a study K+ sample, the mean [K+]e was significantly lower during the episode(s) of VT compared with the mean [K+]e in the absence of VT (p<.01). CONCLUSIONS: Although it is clear that over the clinically acceptable range of [K+]e and [K+]i concentrations seen in this population, there is no correlation between potassium concentrations and the occurrence of premature ventricular beats, the infrequent association of more serious ventricular ectopy, VT, with lower [K+]e concentrations supports the practice of using serum potassium to guide potassium replacement in patients after cardiac operations.

Coronary Artery Bypass↗

PubMed1999

Surgical ICU recidivism after cardiac operations.

BACKGROUND: Decreasing the ICU length of stay (LOS) after cardiac operations may increase ICU recidivism, obviating the benefit of early discharge. METHODS: From January 1, 1994 to January 1, 1998, there were 2,388 consecutive cardiac operations, from which 2,228 patients were discharged alive from the ICU and had sufficient information to determine their incidence of ICU return, the reasons for their return, their ICU LOS (initial and secondary LOS), and mortality. RESULTS: A decrease occurred in the initial ICU LOS from 1994 through 1997 (medians for 1994, 1995, 1996, and 1997, respectively: 31 h, 26.4 h, 24.5 h, and 24 h; and means, respectively: 69.4 +/- 139.8, 62.8 +/- 114.1, 52.5 +/- 104.0, and 56.2 +/- 103.4 h; p = 0.048). In association with this, however, ICU recidivism increased (as percentage of discharges, respectively: 3.9%, 4.2%, 6.1%, and 8.4%; p = 0.005). Inclusive of secondary ICU LOS, the total ICU LOS hours still decreased over the 4-year period. Most notably, the incidence of readmission increased with longer initial LOS (initial LOS quartiles from shortest to longest: 3.9%, 5.2%, 4.7%, and 9.2%; p = 0.0008). Predictors of ICU recidivism included preoperatively, a history of congestive heart failure, and a lower mean left ventricular ejection fraction (52.7 +/- 19.3% vs 49.8 +/- 21.5%; p = 0.0080); and, postoperatively, an increased mean weight gain (8.5 +/- 5.6 kg vs 10.3 +/- 4.7 kg; p = 0.040) and longer mean initial ventilator time (157 +/- 299 h vs 35 +/- 107 h; p = 0.038). The most common reason for readmission was pulmonary problems. CONCLUSIONS: Over the years studied, the initial ICU LOS after cardiac operations has decreased in association with a significant increase in ICU recidivism. Importantly, however, patients readmitted to the ICU are those with longer initial LOSs. Decreased initial stay does not account for our increased ICU recidivism, and efforts to decrease ICU recidivism can focus on the patients with poor preoperative cardiac function and longer initial ICU stays.

Aged↗

PubMed1997

Predictors of CABG within one year of successful PTCA: a retrospective, case-control study.

BACKGROUND: We previously have established characteristics predictive of the need for coronary artery bypass grafting (CABG) over many years after successful percutaneous transluminal coronary angioplasty (PTCA). In this study, we examined the factors associated with the need for CABG within 1 year of successful PTCA, and the recent impact of newer, catheter-based technologies. METHODS: From January 1982 through December 1995, 234 patients underwent CABG within 1 year of a successful "index" PTCA at our hospital. Emergency operations within 12 hours of index PTCA were excluded. These cases were matched with 234 controls who underwent a successful index PTCA but did not require a subsequent CABG during the next year. Cases were matched by the date of their index PTCA, and 1-year follow-up was complete for all patients. RESULTS: Before index PTCA there were no differences between the groups in terms of age, sex, diabetes, prior myocardial infarction, ejection fraction, duration of anginal symptoms, hypertension, hyperlipidemia, family history, or obesity (all nonsignificant). At index PTCA the cases had a greater mean number of lesions measuring 70% or greater compared with the controls (2.8 versus 1.8, respectively; p < 0.0001). The cases were more likely to have critical (70% or greater) proximal left anterior descending artery, proximal first obtuse marginal artery, and right posterior descending artery stenoses. The use of stents or atherectomy devices was not significantly more common among the controls (21% of controls versus 17.1% of cases; p = 0.35). Complete revascularization was achieved in significantly fewer of the cases than the controls (91 versus 156, respectively; p < 0.0001). The cases underwent CABG at a mean of 3 months (86% within 6 months) after PTCA. Among those who had a diagnostic catheterization, 52% of the patients had both restenosis of a dilated lesion and progression of other disease. Only 5 of 75 patients who had restenosis of a dilated lesion had a stent or an atherectomy device used at index PTCA. Of note, 13% (30 of 234) required an emergency operation, with an overall operative mortality rate of 3% (7 of 234). CONCLUSIONS: Although the likelihood of local restenosis is decreased by newer interventional techniques, the need for CABG within 1 year after successful PTCA is not diminished. The number of critical lesions and their location are the best predictors of the need for early CABG. If early post-PTCA CABG is to be avoided, patients who cannot be completely revascularized by PTCA should be revascularized by CABG.

Angioplasty, Balloon, Coronary↗

PubMed1995

CABG after successful PTCA: a case-control study.

We sought characteristics predictive of the need for operative revascularization subsequent to a successful coronary angioplasty. Through June 1993, 128 patients who had successful percutaneous transluminal coronary angioplasty (PTCA) between January 1982 and March 1989 required subsequent coronary artery bypass grafting (CABG) at our hospital. These cases were matched with 128 controls who had a successful PTCA but did not require subsequent CABG. Controls were matched to cases by the date of their initial PTCA. Before initial PTCA there were no differences between the cases and controls in terms of age, sex, prior myocardial infarction, ejection fraction, duration of anginal symptoms, hypertension, hyperlipidemia, family history, or obesity (all not significant). A greater number of cases had diabetes (35 versus 18; p = 0.009). Angiography before initial PTCA revealed that cases had a greater mean number of total lesions (4.1 versus 3.3; p = 0.002) and a higher incidence of left anterior descending and circumflex artery stenoses of 70% or greater (98 versus 75 and 57 versus 34, respectively; p = 0.006). The mean number of lesions successfully dilated was greater in cases (2.4 versus 1.7; p = 0.0001). Cases had CABG at a mean interval of 16.7 +/- 23 months. There were 17 late deaths among cases and 9 among the controls at a mean of 38.6 +/- 30 months. The survival probability at 5 years was 94.5% for controls and 87.9% for cases (p = 0.048). Initial revascularization by PTCA is followed by CABG at a brief interval in a subset of patients who have markers of more severe disease than do patients who do not require early CABG.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗

PubMed1993

Lidocaine prophylaxis in coronary revascularization patients: a randomized, prospective trial.

Life-threatening ventricular ectopy can occur after cardiac operations. The actual incidence of ventricular ectopy and the ability to prevent it by the routine prophylactic use of lidocaine hydrochloride have not been established. We performed a double-blind, randomized, prospective trial involving 109 patients undergoing elective coronary artery revascularization. Patients received either lidocaine (n = 54) or a placebo (n = 55) after separation from bypass. A Holter monitor was affixed to each patient for subsequent review, and bedside intensive-care monitors with alarms were used for "real-time" surveillance. The code was broken when potentially malignant ventricular ectopy or side effects attributable to the study drug were noted. Three lidocaine patients and 2 placebo patients were dropped from the study because of hemodynamic instability or bleeding. Of the remaining 104 patients, the code was broken in 12 (24%) of the 51 in the lidocaine group (9 for ectopy and 3 for mental status changes) and 10 (19%) of the 53 in the placebo group (all for ectopy) (p = not significant). Twenty-four-hour Holter monitor evaluation demonstrated occasional ventricular ectopy in all patients and nonsustained ventricular tachycardia in 28% in the lidocaine group and 48% in the placebo group (p = not significant). The mean number of runs of ventricular tachycardia per patient was 0.53 in the lidocaine group and 1.6 in the placebo group (p = 0.035). There were no significant differences in terms of other ventricular ectopy, morbidity, or mortality. No ventricular fibrillation occurred in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗

PubMed1992

CO2 laser annular thermokeratoplasty: a preliminary study.

Since most techniques of refractive surgery currently in use or being developed have the potential for significant side effects, there is a need for investigating alternative procedures. We herein report on the use of a pulsed CO2 laser beam delivered through a pair of complementary axicons to produce a ring of stromal collagen contraction resulting in the flattening of the corneal apex of cadaver eyes. Irradiances of 29 W/cm2 and 23 W/cm2 were used for rings of 5.5 mm and 7.0 mm, respectively. The creation of a ring of 7.0 mm in diameter did not affect the corneal curvature significantly but when the diameter was reduced to 5.5 mm, substantial flattening proportional to the dose of radiation took place. In our system, it was possible to achieve up to 11.3 diopters of mean keratometry flattening (90 joules, 5.5 mm of diameter). In addition, a 1 mm posterior displacement of the corneal dome without histological evidence of closure of the iridocorneal angle was observed. Annular thermokeratoplasty (ATK) may minimize side effects encountered with other refractive procedures since it does not require ablation, incisions, or interaction with the central optical zone.

Cadaver↗

PubMed1992

Comparison of two transfusion strategies after elective operations for myocardial revascularization.

We performed a prospective, randomized trial of two different strategies for postoperative packed red blood cell replacement in 39 autologous blood donors undergoing elective myocardial revascularization. The "liberal" group received blood to achieve a hematocrit value of 32%, and the "conservative" group received transfusions for a hematocrit value less than 25%. Although the groups had significantly different mean hematocrit values from the fourth postoperative hour (28.7% versus 31.2%) through the fifth postoperative day (28.4% versus 31.3%), there were no significant differences in fluid requirement, hemodynamic parameters, or hospital complications. Significantly fewer units of packed cells were required in the conservatively transfused group (20 units/20 patients) compared with the liberally transfused group (37 units/18 patients) (p = 0.012). Exercise tests were performed on the fifth and sixth postoperative days, with a transfusion being given to the conservative group between tests. Although a significant improvement in exercise endurance occurred in the conservative group receiving a transfusion (p = 0.008), no significant difference in duration or degree of exercise was demonstrated between the two groups on either day. In comparing these two groups of profoundly anemic patients, we identified no adverse consequence associated with the greater degree of hemodilution and could identify no correlation between hematocrit value and exercise capacity. We conclude that although the limits of hemodilution are still poorly defined, postoperative blood transfusion in revascularized patients should be guided by clinical indications and not by specific hematocrit values.

Anemia↗