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Biomedical subjects

R L Patel

Publications and source records attributed to R L Patel.

28 records · Page 2Linked to original sources
PubMed1995

Cardiopulmonary bypass: perioperative cerebral blood flow and postoperative cognitive deficit.

Increased cerebral blood flow occurring during cardiopulmonary bypass as a result of changes in arterial carbon dioxide tension during acid-base regulation is thought to increase postoperative cognitive dysfunction. We studied 70 patients undergoing coronary artery bypass procedures who were randomized to two different acid-base protocols: pH-stat or alpha-stat regulation. Cerebral blood flow, cerebral blood flow velocity, and cerebral oxygen metabolism were measured before bypass, during bypass (hypothermic [28 degrees C] and normothermic phases), and after bypass. Detailed cognitive tests were conducted before operation and 6 weeks after operation. During 28 degrees C bypass, cerebral blood flow was significantly (p < 0.05) higher in the pH-stat group than in the alpha-stat group (41 +/- 2 versus 24 +/- 2 mL.100 g-1.min-1), and cerebral blood flow velocity was significantly increased in the pH-stat group and significantly decreased in the alpha-stat group (152% +/- 10% versus 78% +/- 7%). Cerebral extraction ratio of oxygen demonstrated a relatively greater disruption of autoregulation in the pH-stat group than in the alpha-stat group with relative hyperemia of 0.12 +/- 0.02 versus 0.26 +/- 0.03, respectively, during 28 degrees C bypass. Using the criterion of deterioration in three or more neuropsychologic tests, a significantly higher proportion of patients in the pH-stat group fared less well than in the alpha-stat group (49% +/- 17% versus 20% +/- 13%). Patients in the alpha-stat group experienced less disruption of cerebral autoregulation during hypothermic cardiopulmonary bypass, and this was accompanied by a reduction in postoperative cognitive dysfunction.

Acid-Base Equilibrium↗
PubMed1995

A comprehensive electrophysiological evaluation of phrenic nerve injury related to open-heart surgery.

A prospective electrophysiological study of phrenic nerve was performed in 59 subjects undergoing open-heart surgery. The nerve was stimulated percutaneously at the neck and the diaphragmatic response was recorded with surface electrodes placed over the 8th intercostal space. The latency, amplitude, duration and area of the evoked response were measured before and after the operation. Post-operatively no response was elicited in 2 patients bilaterally, in 5 from the left and in 2 from the right. Comparison of the post-operative with the pre-operative group values in the remaining subjects showed that the amplitude and area of the left phrenic were lower in the post-operative study, indicating that some of the nerve fibres were not conducting. There were no statistically significant differences between pre and post-operative values of latency or duration on the left or any of the parameters on the right. Our findings suggest that the amplitude and area of the diaphragmatic response are more sensitive than latency in detecting phrenic nerve paresis associated with open-heart surgery.

Aged↗
PubMed1993

Hyperperfusion and cerebral dysfunction. Effect of differing acid-base management during cardiopulmonary bypass.

Alterations in cerebral blood flow (CBF) occurring during cardiopulmonary bypass (CPB), which are thought to be responsible for increased morbidity, are probably related to changes in arterial carbon dioxide during acid-base management. In this study, 70 patients undergoing elective coronary artery bypass surgery (CABS) were randomised to one of two differing, but widely practised, cardiopulmonary bypass acid-base protocols; pH-stat and alpha-stat. Cerebral blood flow was measured during surgery using the xenon-133 isotope clearance technique. Cerebral oxygen metabolism was measured as the cerebral metabolic rate for oxygen (CMRO2) and matching of the cerebral blood flow to oxygen demand as the cerebral extraction ratio for oxygen (CERO2). Detailed neuropsychological tests were conducted in all patients before surgery and repeated at 6 weeks after surgery for assessment of changes in cognitive function. During hypothermic (28 degrees C) CPB, CBF was significantly greater (P < 0.001) in the pH-stat group (41 ml/100 g per min; 95% confidence intervals (CI), 39-43) than in the alpha-stat group (24 ml/100 g per min; 95% CI, 22-26). The cerebral extraction ratio for oxygen indicated a degree of mismatch of cerebral perfusion and demand during CPB in both pH-stat and alpha-stat groups (0.12; 95% CI, 0.11-0.14 and 0.25; 95% CI, 0.22-0.28, respectively). This mismatch was far more pronounced in the pH-stat group than in the alpha-stat group, indicating greater disruption in cerebral autoregulation in the former group.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1992

Elective pneumonectomy: factors associated with morbidity and operative mortality.

We have retrospectively reviewed hospital records of 197 consecutive patients undergoing pneumonectomy for neoplastic disease between 1985 and 1990 to identify predictors of outcome. Seventeen of the 197 patients died during their hospital stay (8.6%; 95% confidence intervals, 6.7% to 11.2%). The most significant predictors of in-hospital mortality were presence of coexisting medical conditions (p less than 0.001), respiratory function tests showing an obstructive picture with a forced expiratory volume in 1 second/forced vital capacity ratio of less than 0.55 (p less than 0.001), 24-hour fluid replacement of more than 3 L (p less than 0.05), postoperative pulmonary edema (p less than 0.001), respiratory tract infection with positive sputum culture (p less than 0.01), postoperative renal failure (p less than 0.001), and cardiac arrhythmias (p less than 0.001). There were 232 postoperative management, problems occurring in 197 patients. The most significant predictors of postoperative morbidity were continued cigarette smoking up to the time of operation (p less than 0.05), perioperative blood loss or more than 2 L (p less than 0.05), and infusion of more than 3 L of fluid in the first 24 hours (p less than 0.05). Although retrospective analyses must be interpreted with caution, this study has identified preoperative and perioperative factors associated with in-hospital morbidity and mortality after pneumonectomy.

Adult↗
PubMed1992

Effect of differing acid-base regulation on cerebral blood flow autoregulation during cardiopulmonary bypass.

Cerebral dysfunction following cardiopulmonary bypass may be aggravated by altered autoregulation of cerebral blood flow. We have used trans-cranial Doppler to measure middle cerebral artery blood flow velocity during cardiopulmonary bypass managed by either pH-stat or alpha-stat acid-base protocols. Fourteen patients were studied, 7 in each group. During bypass at 28 degrees C, patients underwent incremental alterations in mean arterial pressure from 20-90 mmHg, maintaining systemic perfusion flow at 1.75 L/min per m2. The cerebral extraction ratio of oxygen was measured to indicate matching of cerebral blood flow to demand. The pH-stat group showed a pressure passive cerebral circulation with significant (r = 0.999, P less than 0.05) increase in blood flow velocity with increasing arterial pressure. This also occurred in alpha-stat group during the pressure range of 20-50 mmHg (r = 0.951, P less than 0.05). During the pressure range of 50-90 mmHg in alpha-stat group the change in flow velocity (0.16 cm/sec per mmHg) was significantly (P less than 0.05) less than that in pH-stat group (0.58 cm/second per mmHg). The cerebral extraction ratio of oxygen was less depressed in the alpha-stat group than in the pH-stat group, indicating more appropriate matching of cerebral blood flow and tissue demand. These results suggest that, during alpha-stat managed cardiopulmonary bypass, cerebral blood flow velocity is less subject to wide pressure alteration than pH-stat.

Acid-Base Equilibrium↗
PubMedDate not supplied

Primary left atrial fibrosarcoma.

An elderly female with refractory cardiovascular symptoms due to functional mitral stenosis secondary to a primary left atrial fibrosarcoma is described. The symptoms are often nonspecific and most of the patients present first time with hemodynamic compromise. A high index of suspicion is essential for the early diagnosis of these highly malignant cardiac tumors because of their rarity, a wide spectrum of nonspecific symptoms and poor survival.

Aged↗
PubMedDate not supplied

Hemofiltration in a cardiac intensive care unit: time for a rational approach.

The typical annual expenditure for patients requiring continuous hemofiltration (CHF) is high. To audit the benefit of this expensive treatment, the outcome of 48 consecutive patients (34 men, 14 women; mean age, 65 years) requiring hemofiltration for acute renal failure was analyzed during a period of 24 months. The operations performed were 26 CABG, 8 AVR, 3 AVR/MVR, 2 post infarction VSD repairs, and 1 thoracoabdominal aneurysmectomy. Indications for hemofiltration were oliguria and fluid overload in 69%, uremia in 56%, acidosis in 33%, and hyperkemia in 13%. Twenty five patients (52%) died while in the hospital, and 10 more died within 9 months of discharge. Of the remaining 13 survivors, 6 (46%) were classified as III or IV according to the New York Heart Association classification system. The mean ITU and hospital stay per patient requiring CHF was 15.3 days and 25.4 days, respectively. There were no statistically significant differences between patients who did and did not survive in the hospital in age, pre-operative renal function, ejection fraction, duration of cardiopulmonary bypass, or urine output before CHF. However, there were no survivors when the cardiac index was less than 1.7 L/m2 and adrenalin requirement was more than 30 micrograms/min before CHF (seven patients). These results suggest that the short- and long-term outcome in patients requiring CHF after cardiac surgery is poor. Considering the large demand on resources, the use of CHF should be rationalized, particularly in patients with persistent low cardiac output.

Acute Kidney Injury↗
PubMedDate not supplied

A survey of hospital morbidity, mortality and quality of life following coronary artery bypass surgery in a UK Indo-Asian population.

To survey the in-hospital morbidity, mortality, length of stay in the intensive therapy unit (ITU) and hospital and quality of life in patients of Indo-Asian origin following coronary artery bypass (CABG) surgery, 345 consecutive patients (mean age 58 years; SD 8.9; range 32-88 years) undergoing primary, isolated CABG were studied. Non-elective CABG was undertaken in 41% of patients. The left anterior descending artery (LAD) was grafted in 89%, although in 30% of these the internal mammary artery (IMA) was not used. Following CABG, the hospital morbidity and mortality was within the expected range, although there was a trend towards higher in-hospital mortality in the Parsonnet low risk group of patients. The length of ITU and hospital stay was not prolonged. Using the SF-36 questionnaire in postoperative patients, low quality of life scores were obtained for six of the eight modalities tested including physical functioning, bodily pain and general health perception. The low quality of life scores and IMA usage in Indo-Asians needs to be addressed.

Adult↗
PubMedDate not supplied

Contamination of the surgeon's bare and gloved fingertips in cardiac operations.

The surgeon's bare fingertips and the external surface of gloved fingertips were examined for contamination by bacteria during the course of 27 cardiac surgical operations. Following the surgical scrub, positive colony counts were obtained in 20 (74%) of bare fingertip impressions (median colony count 4 [inter-quartile range, IQR, 0-9)], while at the conclusion of surgery positive counts were obtained in 15 (55.6%) fingertip impressions (median count 1 [IQR 0-6]; range 0-247; paired Wilcoxon test p = NS). Furthermore, positive colony counts at the start of the operation were obtained in none of the gloved fingertip impressions and at conclusion of surgery in 17 (62.9%) of the gloved fingertip impressions (median count 2 [IQR 0-6] p = 0.0002). There was no significant relationship between the total colony count on gloved fingertip impressions and the length of surgery (Pearson's r = 0.17, p = NS). Contrary to expectations there was no significant increase in the colony count on the bare fingertips at the conclusion of surgery. Although there was an increase in the bacterial count on the surgeon's gloved fingertips, this increase did not correlate with the length of surgery.

Cardiac Surgical Procedures↗