Changes in ionized calcium concentrations and acid-base status during abdominal aortic vascular surgery.
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Abdominal aortic surgery may produce significant haemodynamic instability (from a combination of factors: hypovolaemia, acid-base disturbances, vasoactive metabolite release from ischaemic tissues and hypocalcaemia). Calcium is often given after aortic unclamping to attenuate this instability. We studied 20 patients undergoing elective abdominal aortic surgery and observed a triphasic change in ionized calcium concentrations and acid-base status. Initially, during the cross-clamp period (when patients were cardiovascularly stable), ionized calcium concentrations decreased significantly (mean 1.06 (SD 0.08) to 0.91 (0.13) mmol litre-1; P < 0.01), while a significant metabolic acidosis developed (pH 7.38 (0.05) to 7.30 (0.05); P < 0.05). Second, release of the aortic cross-clamp resulted in further acidosis (pH 7.27 (0.05) (P < 0.05) mixed respiratory and metabolic) with a decrease in mean arterial pressure, with no change in ionized calcium concentrations. The third phase was associated with spontaneous restoration of acid-base status and ionized calcium concentrations to normal over 2 h. There was no correlation between units of blood given, volume of blood lost, fluid volume given or duration of aortic cross-clamping and degree of ionized hypocalcaemia. We conclude that ionized hypocalcaemia occurred during the cross-clamp period of aortic surgery, was unrelated to the volume of blood given and did not appear to be responsible for the changes in arterial pressure during surgery. (+info)
Intraoperative cardiac troponin T release and lactate metabolism during coronary artery surgery: comparison of beating heart with conventional coronary artery surgery with cardiopulmonary bypass.
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OBJECTIVE: To compare cardiac troponin T release and lactate metabolism in coronary sinus and arterial blood during uncomplicated coronary grafting on the beating heart with conventional coronary grafting using cardiopulmonary bypass. DESIGN: A prospective observational study with simultaneous sampling of coronary sinus and arterial blood: before and 1, 4, 10, and 20 minutes after reperfusion for analysis of cardiac troponin T and lactate. Cardiac troponin T was also analysed in venous samples taken 3, 6, 24, 48, and 72 hours after surgery. SETTING: Cardiac surgical unit in a tertiary referral centre. PATIENTS: 18 patients undergoing coronary grafting on the beating heart (10 single vessel and eight two-vessel grafting) and eight undergoing two-vessel grafting with cardiopulmonary bypass. RESULTS: Cardiac troponin T was detected in coronary sinus blood in all patients by 20 minutes after beating heart coronary artery surgery before arterial concentrations were consistently increased. Peak arterial and coronary sinus cardiac troponin T values on the beating heart during single (0.03 (0 to 0. 05) and 0.09 (0.07 to 0.16 microg/l, respectively) and two-vessel grafting (0.1 (0.07 to 0.11) and 0.19 (0.14 to 0.25) microg/l) were lower than the values obtained during cardiopulmonary bypass (0.64 (0.52 to 0.72) and 1.4 (0.9 to 2.0) microg/l) (p < 0.05). The area under the curve of venous cardiac troponin T over 72 hours for two-vessel grafting on the beating heart was less than with cardiopulmonary bypass (13 (10 to 16) v 68 (26 to 102) microg.h/l) (p < 0.001). Lactate extraction began within one minute of snare release during beating heart coronary surgery while lactate was still being produced 20 minutes after cross clamp release following cardiopulmonary bypass. CONCLUSIONS: Lower intraoperative and serial venous cardiac troponin T concentrations suggest a lesser degree of myocyte injury during beating heart coronary artery surgery than during cardiopulmonary bypass. Oxidative metabolism also recovers more rapidly with beating heart coronary artery surgery than with conventional coronary grafting. Coronary sinus cardiac troponin T concentrations increased earlier and were greater than arterial concentrations during beating heart surgery, suggesting that this may be a more sensitive method of intraoperative assessment of myocardial injury. (+info)
Role of the surgical trainee in upper gastrointestinal resectional surgery.
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The 'New Deal' set out by the Department of Health in 1991, together with the introduction of specialist 6-year training grades by Calman in 1993, has resulted in a decrease in available training time for surgeons in the UK. There is also an emerging belief that surgical procedures performed by trainees might compromise patient outcome. This study examines the level of trainee experience in a specialist gastrointestinal unit and whether operation by a trainee surgeon adversely affects patient outcome. All patients in the University Department of Surgery, Royal Infirmary, Edinburgh, undergoing oesophagogastric, hepatic or pancreatic resection between January 1994 and December 1996 were entered into the study. The early clinical outcome (in-hospital mortality and morbidity, considered in three groups: anastomotic leak, other technique-related complications and non-technique-related complications) was evaluated with regard to the grade of surgeon (consultant or trainee) performing the operation. Of the 222 patients undergoing major upper gastrointestinal resection during the study period, 100 (45%) were operated on by trainees. Trainees were assisted and closely supervised by consultants in all but six resections. There was no major difference in mortality rate (consultant, 4.1% vs trainee, 5%), incidence of non-technique-related complications (consultant, 6.7% vs trainee, 7.1%), anastomotic leaks (consultant, 10.7% vs trainee, 5%) or technique-related complications (consultant, 18.9% vs trainee, 15%) between the two grades of surgeon. In a specialist unit, the early clinical outcome of patients undergoing major upper gastrointestinal resection by supervised trainees is no worse than in those operated on by consultants. Participation of trainees in such complex procedures enhances surgical training and does not jeopardise patient care. (+info)
Changes in plasma potassium concentration during carbon dioxide pneumoperitoneum.
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Hyperkalaemia with ECG changes had been noted during prolonged carbon dioxide pneumoperitoneum in pigs. We have compared plasma potassium concentrations during surgery in 11 patients allocated randomly to undergo either laparoscopic or open appendectomy and in another 17 patients allocated randomly to either carbon dioxide pneumoperitoneum or abdominal wall lifting for laparoscopic colectomy. Despite an increasing metabolic acidosis, prolonged carbon dioxide pneumoperitoneum resulted in only a slight increase in plasma potassium concentrations, which was both statistically and clinically insignificant. Thus hyperkalaemia is unlikely to develop in patients with normal renal function undergoing carbon dioxide pneumoperitoneum for laparoscopic surgery. (+info)
Acute renal failure following cardiac surgery.
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BACKGROUND: Acute renal failure requiring dialysis (ARF-D) occurs in 1.5% of patients following cardiac surgery, and remains a cause of major morbidity and mortality. While some preoperative risk factors have been characterized, the influence of preoperative and intraoperative factors on the occurrence of ARF following cardiac surgery is less well understood. METHODS: Preoperative and intraoperative data on 2843 consecutive adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) from February 1, 1995 to February 1, 1997 were recorded and entered into a computerized database. Two definitions of renal failure were employed: (i) ARF defined as a rise in serum creatinine (Cr) of 1 mg/dl above baseline; and (ii) ARF-D defined as the development of ARF for which some form of dialytic therapy was required. The association between preoperative and intraoperative variables and the development of ARF was assessed by multivariate logistic regression. RESULTS: A total of 2672 of the 2844 patients underwent isolated coronary artery bypass grafting (CABG) surgery, the remaining 172 underwent valve surgery with or without bypass grafting. Of the CABG patients 7.9% developed ARF and 0.7% developed ARF-D. The mortality for patients who developed ARF was 14% (OR 15, P = 0.0001) compared with 1% among those who did not develop ARF. The mortality for CABG patients who developed ARF-D was 28% (OR 20, P = 0.0001) compared with 1.8% among those who did not require dialysis. Variables that were significantly associated with the development of ARF by multivariate analysis included: increased age, elevated preoperative serum Cr, duration of CPB, presence of a carotid artery bruit, presence of diabetes, reduced cardiac ejection fraction and increased body weight. Variables independently associated with ARF-D included serum Cr, duration of CPB, carotid artery bruit and presence of diabetes. The utility of these models for predicting the development of ARF and ARF-D was confirmed by bootstrapping techniques. Because of the small number of patients who underwent valve surgery, none of these variables were significantly associated with the development of ARF or ARF-D in this group of patients. CONCLUSION: The development of ARF or ARF-D is associated with a high mortality following CABG surgery. We have identified perioperative variables, which may be useful in stratifying risk for the development of ARF. (+info)
Improved success rate in reoperative parathyroidectomy with intraoperative PTH assay.
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OBJECTIVE: The clinical usefulness of preoperative localization and intraoperative PTH assay (QPTH) in primary hyperparathyroidism have been established. However, without the use of QPTH, the parathyroidectomy failure rate remains 5% to 10% in large reported series and is probably much higher in the hands of less experienced parathyroid surgeons. Persistent hypercalcemia requires another surgical procedure. The authors compared the outcomes in 50 consecutive patients undergoing more difficult secondary parathyroidectomy with and without the adjunctive support of QPTH. METHODS: Two groups of similar patients underwent reoperative parathyroidectomy for failed surgery or recurrent disease. The successful return to normocalcemia in group I, with QPTH used to localize and confirm complete excision of all hyperfunctioning glands, was compared with group II, who did not have this intraoperative adjunct. RESULTS: In 31/33 patients in group I, calcium levels returned to normal. With good preoperative localization studies, 17 patients underwent successful straightforward parathyroidectomies as predicted by QPTH. In the other 14 patients, QPTH assay proved extremely beneficial by facilitating localization with differential venous sampling; measuring the increase in hormone secretion after massage of specific areas; recognizing suspicious nonparathyroid tissue excised without a decrease in hormone levels, avoiding frozen-section delay; and correctly identifying the excision of abnormal tissue despite false-positive/false-negative sestamibi scans. In group II, who underwent surgery before QPTH was available, 4 of 17 patients (24%) remained hypercalcemic after extensive reexploration. CONCLUSION: With the intraoperative hormone assay used to facilitate localization and confirm excision of all hyperfunctioning tissue, the success rate of reoperative parathyroidectomy has improved from 76% to 94%. (+info)
Patterns of nodal metastases in palpable medullary thyroid carcinoma: recommendations for extent of node dissection.
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OBJECTIVE: To establish the frequency, pattern and location of cervical lymph node metastases from palpable medullary thyroid carcinoma (MTC). Recommendations are made regarding the extent of surgery for this tumor. SUMMARY BACKGROUND DATA: Medullary thyroid carcinoma is a tumor of neuroendocrine origin that does not concentrate iodine. Surgical extirpation of the thyroid tumor and cervical node metastases is the only potentially curative therapeutic option. Patterns of node metastases in the neck and guidelines for the extent of dissection for palpable MTC are not well established. METHODS: Seventy-three patients underwent thyroidectomy for palpable MTC with immediate or delayed central and bilateral functional neck dissections. The number and location of lymph node metastases in the central (levels VI and VII) and bilateral (levels II to V) nodal groups were noted and were correlated with the size and location of the primary thyroid tumor. Intraoperative assessment of nodal status by palpation and inspection by the surgeon was correlated with results of histologic examination. RESULTS: Patients with unilateral intrathyroid tumors had lymph node metastases in 81% of central node dissections, 81% of ipsilateral functional (levels II to V) dissections, and 44% of contralateral functional (levels II to V) dissections. In patients with bilateral intrathyroid tumors, nodal metastases were present in 78% of central node dissections, 71% of functional (levels II to V) node dissections ipsilateral to the largest intrathyroid tumor, and 49% of functional (levels II to V) node dissections contralateral to the largest thyroid tumor. The sensitivity of the surgeon's intraoperative assessment for nodal metastases was 64%, and the specificity was 71%. CONCLUSION: In this series, >75% of patients with palpable MTC had associated nodal metastases, which often were not apparent to the surgeon. Routine central and bilateral functional neck dissections should be considered in all patients with palpable MTC. (+info)
Controlled intraoperative water testing of left-sided colorectal anastomoses: are ileostomies avoidable?
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Anastomotic leakage is a major problem in colorectal surgery, and previous studies have suggested that intraoperative identification of leaks allows repair at the time of surgery. This study examined whether testing allowed a defunctioning ileostomy to be safely omitted. A series of 102 consecutive patients underwent left-sided colorectal resection, 52 males and 50 females, mean age 65.7 years (range 16-89 years). After completion of the anastomosis, its integrity was tested by running saline into the rectum, using a manometer, to a maximum distending pressure of 30 cmH2O. Any leaks were repaired and the anastomosis retested. A defunctioning ileostomy was only performed if the anastomosis could not be shown to be leak-proof on testing. Patients underwent a contrast enema on the 8th postoperative day. Twenty-one (20.6%) patients failed the initial leakage test and 3 (3%) patients failed a second test. Two of these 21 patients went on to have a clinical leak, both of which were treated conservatively. Two defunctioning ileostomies were performed at the time of surgery. Sixteen (16.2%) had a leak on radiological testing, and there was clinical evidence of a leak in 5 (4.9%) patients. There were 3 (2.9%) deaths, but none of these had a leak on radiological testing. Incomplete anastomoses were successfully corrected intraoperatively. A defunctioning ileostomy was avoided in 98% of cases. Intraoperative testing to a pressure of 30 cmH2O is helpful in anterior resection, but does not guarantee that an intact anastomosis will remain intact postoperatively. (+info)