Biomedical subjects

Oswaldo Valencia

Publications and source records attributed to Oswaldo Valencia.

7 recordsLinked to original sources

PubMed2006

How safe is it to train residents to perform off-pump coronary artery bypass surgery?

BACKGROUND: The technique of off-pump coronary artery bypass graft (OPCABG) surgery differs considerably from on-pump CABG. This study investigates the impact of surgical training on clinical outcome in patients undergoing OPCABG. METHODS: All 251 OPCABG cases performed by one service over an 18-month period were analyzed. The 83 operations (33%) performed by two trainees under supervision were compared with the 168 operations (67%) performed by an experienced consultant surgeon. Patient and disease characteristics, intraoperative and postoperative data, morbidity and mortality were analyzed using univariate and multivariate analysis. Data were extracted from a prospective database. RESULTS: Patients operated on by the consultant were more likely to have had unstable angina (p = 0.003, odds ratio [OR] = 3.5), impaired left ventricular function (ejection fraction < 0.3; p = 0.005, OR = 2.4), or previous cardiac surgery (p = 0.03). They were more likely to receive three or more grafts (p = 0.017, OR = 2.0). Operative mortality was 2.4% (consultant) and 0% (trainees; p = 0.31). Postoperative morbidity, such as reoperation for bleeding (consultant 3% versus trainees 1.2%), stroke (0.6% versus 1.2%), and hemofiltration (3.6% versus 0%) was similar between the two patient groups. Stay in the intensive care unit was not significantly different in the two groups. CONCLUSIONS: In our experience, trainee surgeons are less likely to operate on patients with unstable angina or cardiac dysfunction. Operative morbidity and mortality are, however, similar in patients operated on by either an experienced consultant surgeon or trainees. We believe OPCABG can be taught safely to trainees under supervision.

Aged↗

PubMed2005

Renal function after cardiac surgery off- versus on-pump coronary artery bypass: analysis using the Cockroft-Gault formula for estimating creatinine clearance.

BACKGROUND: Cardiopulmonary bypass (CPB) is often associated with renal dysfunction, as measured by plasma creatinine levels and hemodialysis rates. This study compared creatinine clearance (CrCl), estimated with the Cockroft and Gault formula, between patients undergoing off-pump coronary artery bypass grafting (OPCAB) versus on-pump CABG (on-CAB). METHODS: Data of 704 consecutive patients were analyzed. Of these patients, 404 underwent OPCAB while 300 had on-CAB. Creatinine clearance, plasma creatinine levels, and clinical outcome were compared between groups. Data between patients who developed new renal impairment, compared to patients with normal postoperative renal function, were also analyzed. RESULTS: Creatinine clearance (preoperative, 74 +/- 25 vs 78 +/- 29 mL/min; day 1, 74 +/- 26 vs 76 +/- 31 mL/min; day 4, 70 +/- 26 vs 72 +/- 29 mL/min) and creatinine levels (preoperative, 99 +/- 25 vs 95 +/- 27 micromol/L; day 1, 101 +/- 29 vs 104 +/- 35 micromol/L; day 4, 110 +/- 44 vs 113 +/- 60 micromol/L), as well as postoperative complications (stroke 1% vs 1%; hemofiltration 1.5% vs 3.7%; death 1.2% vs 2.3%), were overall similar between OPCAB and on-CAB patients. Patients with preoperative CrCl less than 50 mL/min had higher creatinine levels in the on-CAB group on day 1 (p = 0.026), although CrCl was similar between groups. Development of new CrCl less than 50 mL/min postoperatively was associated with higher rates of intraaortic balloon pump insertion, re-sternotomy, hemofiltration, intensive care and hospital stay, without difference between groups. Female sex, low body mass index, high preoperative creatinine levels, and advanced age were associated with deterioration in CrCl. CONCLUSIONS: Currently, the rate of renal impairment is low after both OPCAB and on-CAB. No significant difference in CrCl could be demonstrated between groups. Deterioration in renal function is associated with higher rates of postoperative complications.

Aged↗

PubMed2004

The role of coronary angiography in acute type A aortic dissection.

OBJECTIVES: In recent years, non-invasive methods have replaced angiography in the diagnosis of aortic dissection. Angiography maybe used to evaluate coexisting coronary artery disease (CAD), which can delay surgery and increase the risk of rupture. We set out to examine the role of angiography in acute aortic dissection. METHODS: A retrospective analysis of patients who underwent repair of acute aortic dissection between January 1992 and June 2002 was conducted. The effect of angiography on the need for concomitant coronary artery surgery (CABG), delay to surgery and outcome were analysed. RESULTS: Seventy-four patients were identified. Initial diagnosis was established by non-invasive techniques. Twenty-three patients (31%) underwent angiography (Group I) in three this was unsuccessful. Three in Group I and four in the non-angiography group (Group II, n=51) had history of angina. One patient in Group I underwent concomitant CABG compared to seven in Group II. The patient who underwent CABG in Group I; and four out of seven in Group II died (NS). Patients who underwent concomitant CABG had a significantly higher mortality rate (P=0.04). Mortality in Group I was 35% (n=8) and in Group II was 29% (n=15) (NS). Mortality rate was also significantly higher in patients who presented with syncope (P=0.01) or hypotension (P=0.04). Median transfer time from arrival at our centre to the operating room was 5 h in Group I and 1.5 h in Group II (P<0.001). Mortality rate was higher in patients who took longer to transfer to the operating room, but this did not reach statistical significance. CONCLUSIONS: We have shown that coronary angiography did not affect the occurrence of CABG and was not associated with improved hospital survival. Furthermore, there is a considerable delay to surgery caused by angiography. Therefore in this setting coronary angiography is not recommended.

Acute Disease↗

PubMed2004

Management of patients undergoing coronary artery bypass graft surgery with mild to moderate aortic stenosis.

BACKGROUND AND AIM OF THE STUDY: The management of patients undergoing coronary artery bypass graft (CABG) surgery with mild to moderate aortic stenosis (AS) remains controversial. The study aim was to examine the outcome in patients with mild to moderate AS undergoing CABG. METHODS: A retrospective analysis was carried out of 200 patients with coronary artery disease requiring CABG and with a peak AS gradient < 40 mmHg measured by Doppler echocardiography, between 1990 and 2000. Among patients, 154 underwent isolated CABG (group A) and 46 CABG + aortic valve replacement (AVR) (group B). RESULTS: Mortality was 2.6% (n = 4) in group A and 6.5% (n = 3) in group B (p = NS). The median AS gradients were 34 and 40 mmHg, respectively. Thirty patients (20%) in group A were in NYHA class III-IV compared to 20 (44%) in group B (p = 0.002). There was no significant difference in postoperative complications. The mean intensive care unit stay was 2.3 and 2.2 days, respectively (p = NS); median postoperative stay was 6 and 8 days, respectively (p = 0.02). During the median follow up period of 4.2 years no patient in group A required AVR. Nine late deaths occurred in group B, none of which was cardiac-related. CONCLUSION: Morbidity and mortality in patients who underwent combined surgery was comparable with that in patients who had isolated CABG. However, none of the patients who underwent only CABG required AVR during the follow up period. It is concluded that patients with mild AS at the time of CABG should not undergo AVR. It is possible that a cut-off AS gradient > 40 mmHg should be considered for combined surgery.

Aged↗

PubMed2003

Analytical methods for calculating the capacity required to operate an effective booked admissions policy for elective inpatient services.

In the UK, hospitals are being encouraged to introduce booked admissions policies for elective inpatient services whereby patients are given a date for hospital admission months in advance rather than being put on a waiting list and then informed of their admission date at short notice. We address the question of what level of capacity is required to operate such a system if cancellations of booked elective patients are to be kept to a low level. Methods are presented for quantifying the day to day variation in bed demand due to emergency admissions, patient initiated cancellations and variable lengths of stay amongst patients.

Admitting Department, Hospital↗

PubMed2002

Booked inpatient admissions and hospital capacity: mathematical modelling study.

OBJECTIVES: To investigate the variability of patients' length of stay in intensive care after cardiac surgery. To investigate potential interactions between such variability, booked admissions, and capacity requirements. DESIGN: Mathematical modelling study using routinely collected data. SETTING: A cardiac surgery department. SOURCE OF DATA: Hospital records of 7014 people entering intensive care after cardiac surgery. MAIN OUTCOME MEASURES: Length of stay in intensive care; capacity requirements of an intensive care unit for a hypothetical booked admission system. RESULTS: Although the vast majority of patients (89.5%) had a length of stay in intensive care of < or = 48 hours, there was considerable overall variability and the distribution of stays has a lengthy tail. A mathematical model of the operation of a hypothetical booking system indicates that such variability has a considerable impact on intensive care capacity requirements, indicating that a high degree of reserve capacity is required to avoid high rates of operation cancellation because of unavailability of suitable postoperative care. CONCLUSION: Despite the considerable enthusiasm for booked admissions systems, queuing theory suggests that caution is required when considering such systems for inpatient admissions. Such systems may well result in frequent operational difficulties if there is a high degree of variability in length of stay and where reserve capacity is limited. Both of these are common in the NHS.

Admitting Department, Hospital↗

PubMed2002

Surgical performance measurement.

The need for effective surgical performance measurement has gained an increasingly high profile in recent years, particularly since events at Bristol Royal Infirmary, where apparent poor performance has prompted the UK Department of Health to instigate a major Public Inquiry. This paper describes issues that concern the measuring and monitoring of surgical performance, and methods that have been devised for judging a good surgeon from the less competent. The authors are a collaborative team composed of specialists in Cardiothoracic surgery and Operational Research analysts with experience of monitoring performance in cardiac surgery. This paper describes concrete examples from that knowledge base.

Clinical Competence↗