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Biomedical subjects

R P Alston

Publications and source records attributed to R P Alston.

At least 19 recordsLinked to original sources
PubMed2005

Dysaesthesia associated with sternotomy for heart surgery.

BACKGROUND: Chronic pain occurs in 40-50% patients following cardiac surgery. Dysaesthesia, either in the form of heightened or diminished skin sensation, are frequently associated with chronic neuropathic pain. Therefore, dysaesthesia in the early postoperative period may predict chronic pain. However, the character and causes of dysaesthesia in the early postoperative period are unknown. The aim of this study was to investigate the incidence, extent, and causes of dysaesthesia following cardiac surgery by sternotomy. METHODS: In a prospective cohort study, 50 patients undergoing sternotomy for cardiac surgery were admitted to the study: 38 underwent coronary artery bypass graft (CABG), nine valve surgery, and three combined surgery. Forty-eight hours postoperatively, acute pain was measured by four-point verbal scale. Manual pinprick and cotton wool brushing was used to detect the areas of dysaesthesia. RESULTS: Some form of dysaesthesia was found in 27 (54%) of the patients. Using multivariate regression analysis, the total area of dysaesthesia was positively associated with CABG surgery and the severity of postoperative pain (P<0.001). CONCLUSION: Dysaesthesia is common in the early postoperative period following cardiac surgery using a sternotomy and is associated with CABG surgery. The association with severity of pain may indicate a neuropathic element that is unrelieved by conventional opioid analgesia.

Adult↗
PubMed2001

Cerebral hypoperfusion in immediate postoperative period following coronary artery bypass grafting, heart valve, and abdominal aortic surgery.

Perioperative levels of jugular bulb oxyhaemoglobin saturation (Sj(O(2))) and lactate concentration (Lj), and postoperative duration of Sj(O(2))<50% were compared between patients undergoing coronary artery bypass grafting (CABG) (n=86), heart valve (n=14) and abdominal aortic (n=16) surgery. Radial artery and jugular bulb blood samples were aspirated after induction of anaesthesia, during re-warming on cardiopulmonary bypass (CPB) (36 degrees C), on arrival in the intensive care unit (ICU) and, subsequently, at 1, 2 and 6 h after ICU admission. Most patients having heart surgery were hypocapnic at 36 degrees C on CPB. Following CABG and heart valve surgery, many patients were hypocapnic whereas after abdominal aortic surgery, most were hypercapnic. During CPB and postoperatively, Sj(O(2)) and Lj were significantly correlated to Pa(CO(2)) and the arterial concentration of lactate (La) respectively (P<0.05). After correction for arterial carbon dioxide tension (Pa(CO(2))) and La, there were no significant changes in Sj(O(2)) or Lj on CPB. Postoperatively, having corrected for Pa(CO(2)), there were significant effects on Sj(O(2)) over all groups as a result of time from surgery (P<0.001) and its interaction with operation type (P<0.001). Following correction for La, there were no postoperative effects on Lj. No significant differences (P=0.2) in duration of Sj(O(2))<50% existed between patients undergoing CABG (1054 (82) min), abdominal aortic (893 (113) min) and heart valve (1073 (91) min) surgery. The lack of significant reciprocal effects on Lj combined with the frequency of hypocapnia and strong influence of Pa(CO(2))()on Sj(O(2)), suggest that Sj(O(2))<50% during CPB and after cardiac surgery represents hypoperfusion as a consequence of hypocapnia rather than cerebral ischaemia.

Aged↗
PubMed2001

Jugular bulb oxyhemoglobin desaturation, S100beta, and neurologic and cognitive outcomes after coronary artery surgery.

UNLABELLED: We reported that a decline in cognitive performance 3 mo after coronary artery bypass grafting surgery is associated with palpable aortic atheroma, but not postoperative jugular bulb oxyhemoglobin saturation (SjO2) <50%. However, the effect of SjO2 on clinical neurologic findings is not known. S100beta is a possible surrogate biochemical marker of brain injury, and we report here the scored clinical neurologic findings in 98 patients from our previous study in relation to SjO2, cognitive performance, aortic atheroma, and S100beta. Patients underwent a scored neurologic examination and cognitive assessment the day before and 3 mo after coronary artery bypass grafting surgery. Intraoperatively, intermittent blood sampling was performed, and postoperatively, the area under the curve describing SjO2 <50% in relation to time was calculated from continuous jugular bulb reflectance oximetry. Palpation was used to assess the ascending aorta for the presence of atheroma. The jugular bulb concentration of S100beta was measured 6 h after completion of surgery. The neurologic score 3 mo after surgery did not correlate with either intra- or postoperative SjO2 (r = 0.111, P = 0.278; and r = -0.074, P = 0.467, respectively). The main determinant of neurologic score at 3 mo was the preoperative neurologic score (r(2) = 0.63, P < 0.001), whereas palpable atheroma of the ascending aorta made a small but significant contribution (r(2) = 0.034, P = 0.004). Neurologic and cognitive scores correlated before surgery (r = 0.226, P = 0.022) and at 3 mo after surgery (r = 0.348, P < 0.001). A preoperative neurologic deficit of two or more had a small but significant negative effect on cognitive performance at 3 mo (standardized beta = -0.097, P = 0.018). There was a significant univariate correlation between S100beta and the 3-mo neurologic score (r = -0.232, P < 0.05), but not a multivariate correlation (beta = -0.090, P = 0.156). IMPLICATIONS: Intraoperative jugular bulb oxyhemoglobin saturation (SjO2) and postoperative SjO2 <50% do not have an important influence on long-term neurologic outcome after coronary artery bypass graft surgery. Subtle preoperative neurology is associated with long-term cognitive decline, and aortic atheroma is a risk factor for both cognitive and neurologic decline.

Arteriosclerosis↗
PubMed2000

Cognition after coronary artery surgery is not related to postoperative jugular bulb oxyhemoglobin desaturation.

During the early postoperative period after coronary artery bypass grafting (CABG) surgery, many patients experience jugular bulb oxyhemoglobin desaturation (SjO(2) < 50%). We sought to determine whether SjO(2) during cardiopulmonary bypass and the early postoperative period influenced long-term cognitive performance after CABG surgery. One hundred two patients completed a battery of cognitive tests the day before and 3 mo after CABG surgery. A General Cognitive Score was generated from these tests as an overall measure of cognitive function. Intraoperatively, SjO(2) was determined by intermittent blood sampling, and postoperatively, the area under the curve of SjO(2) < 50% and time was calculated from continuous reflectance oximetry. No significant correlations between cognitive performance and either intra- or postoperative SjO(2) were found. Preoperative cognitive performance was the main determinant of cognition at 3 mo (r(2) = 0.83, P<0.001), and palpable atheroma of the ascending aorta made a small, but significant, contribution to a decline in cognition (r(2) = 0.018, P = 0.001).

Aged↗
PubMed1999

Continuous monitoring of jugular bulb oxyhaemoglobin saturation using the Edslab dual lumen oximetry catheter during and after cardiac surgery.

Fibreoptic jugular bulb oximetry has been validated for use in the care of severely head-injured patients. We compared bench and fibreoptic methods of measuring jugular bulb oxyhaemoglobin saturation (SjO2) in 33 patients undergoing cardiac surgery both during cardiopulmonary bypass (CPB) and in the early postoperative period. After insertion of a fibreoptic reflectance oximetry catheter into the jugular bulb, it was calibrated against a bench oximeter. Comparisons were made while on CPB (n = 60) and in the postoperative period for up to 18 h (n = 215). There was negligible bias throughout. There were wide limits of agreements (mean difference +/- 2SD) between the two methods during operation (-20.29% to 18.05%), whereas after operation the limits of agreement were far narrower (-6.39% and 7.45%). Measurement of SjO2 by the fibreoptic method compared poorly with bench oximetry during CPB but there was good agreement between the two methods in the early postoperative period.

Adult↗
PubMed1999

Aerobic, anaerobic and combination estimates of cerebral hypoperfusion during and after cardiac surgery.

We studied 15 patients undergoing cardiac surgery involving hypothermic cardiopulmonary bypass (CPB). Cerebral arteriovenous difference in oxygen content (AVDO2) was significantly less during CPB and for up to 18 h after operation compared with pre-CPB values (P < 0.05). There were no significant changes in mean jugular bulb oxyhaemoglobin saturation (SjvO2), cerebral arteriovenous difference in lactate content or lactate-oxygen index (LOI). SjVO2 and arterial carbon dioxide tension (PaCO2) (P = 0.005) were positively correlated as were AVDO2 and haemoglobin concentration (P = 0.012). AVDO2 and PaCO2 (P = 0.007) were negatively correlated as were LOI and arterial oxyhaemoglobin saturation (P = 0.037). There were no significant correlations between mean arterial pressure and any of the variables. SjVO2 and AVDO2 may require correction for changes in PaCO2 and haemoglobin concentration before relating these variables to cerebral outcome.

Aged↗
PubMed1998

Jugular venous desaturation following cardiac surgery.

Twenty-two patients undergoing coronary artery bypass surgery underwent postoperative measurement and recording of jugular venous oxyhaemoglobin saturation (SjO2) with desaturation defined as a value of less than 50% for 5 min or longer. Fifteen of the 22 patients monitored experienced desaturations. An average of four episodes were experienced by those 15 patients (range 1-14). The mean duration of a single episode was 46 (range 5-212) min whilst mean total duration of desaturation was 175 (range 5-570) min. The mean duration of desaturation in the 15 patients, expressed as a percentage of monitored time, was 21.1% (range 0.58%-61.96%). SjO2 desaturation, possibly indicating cerebral hypoperfusion, occurs in the early post-operative period following cardiac surgery.

Coronary Artery Bypass↗
PubMed1998

Propofol does not ameliorate cerebral venous oxyhemoglobin desaturation during hypothermic cardiopulmonary bypass.

UNLABELLED: Reductions in cerebral venous oxyhemoglobin saturation (SjO2) occur during the rewarming phase of hypothermic cardiopulmonary bypass (CPB). We prospectively investigated the effects of propofol on these reductions in SjO2 (SjO2 <50%). Fiberoptic jugular bulb catheters were inserted in 30 patients undergoing coronary artery bypass grafting. Patients were randomly allocated to a test or control group. Test group patients (n = 15) received a propofol IV infusion titrated to electroencephalographic burst suppression during CPB. No significant differences in SjO2 <50% were found between the groups either by blood sampling and bench oximetry or fiberoptic oximetry. The arteriovenous difference in lactate concentration became negative in 59 of 120 samples. Propofol was associated with an increased incidence of hypotension (mean arterial pressure <50 mm Hg) (P = 0.023), an increased requirement for vasoconstrictor therapy (P = 0.025), and increases in the lactate oxygen index (P < 0.01). Propofol, when administered in doses that produce electroencephalographic burst suppression, does not attenuate the frequency or extent of reductions of SjO2 below 50% during rewarming from hypothermic CPB. However, it is associated with arterial hypotension and an increase in cerebral anaerobic metabolism. IMPLICATIONS: Reductions in cerebral venous oxyhemoglobin saturation during the rewarming phase of cardiopulmonary bypass may be related to brain injury. When administered in doses sufficient to produce electroencephalographic burst suppression, propofol did not attenuate the frequency or extent of such reductions in cerebral venous oxyhemoglobin saturation.

Aged↗
PubMed1997

Guidelines and cardiac anaesthetists. Not in my back yard.

Guidelines for cardiac anaesthesia could reduce irrational variation in practice and so improve cardiac surgical outcome. In October 1994, a postal survey was undertaken to determine the views and attitudes of consultant cardiac anaesthetists in the United Kingdom towards guidelines. One hundred and forty correctly completed questionnaires were returned (minimum response rate 64%). Eighty-nine per cent believed that guidelines were of value in medicine whilst only 21% wanted national guidelines for cardiac anaesthesia. Responses to other parts of the questionnaire showed that those against guidelines for cardiac anaesthesia were less positive towards their advantages and more negative to their disadvantages compared with those in their favour. The majority of cardiac anaesthetists, although believing them to be valuable in medicine, do not want guidelines for cardiac anaesthesia because they are concerned that guidelines would be inflexible and would neither reduce variation in, nor improve the quality of, cardiac anaesthesia.

Anesthesiology↗