Pathophysiological mechanism of renal injury induced by cardiopulmonary bypass [CPB]: is there a possible protective role of N-acetylcysteine [NAS] as a radical scavenger?

Despite improvements in surgical techniques, myocardial protection, and perioperative care, acute renal failure [ARF] after cardiopulmonary bypass [CPB] represents one of clinician problems as it associated with unacceptable high mortality. Oxygen free radicals are important components that may be involved in the pathophystological tissue alterations observed during ischemia/reperfusion [I/R]. we evaluated the possible renoprotective role of N-acetylcysteine [NAC] as a free radical scavenger against oxidative stress during I/R injury of the kidney induced by CPB in patients with normal renal function compared with placebo, a prospective randomized study where thirty patients of ischemic heart disease who underwent coronary artery bypass grafting [CABG] were divided into two groups. The study group [n=15] with mean age 61.20 +/- 8.01 received NAC intravenously in a dose of 50 mg/Kg/day, given as 25 mg/Kg' twice daily for successive 3 days, and the placebo group [n=15] with mean age 60.60 +/- 8.41 received 0.5 cc/kg saline twice in 24h for three days before CABG. Intraoperative as well as the clinical outcome in both groups such as the type of graft used perioperative myocardial infarction, pump time aortic cross clamp time, the need for intra-aortic balloon, incidence of arrhythmias, and the of ICU stay were evaluated. Arterial blood sampling were collected from both groups after induction of anesthesia, and, 241 after cessation of CPB to measure serum creatinine, creatinine clearance [as markers of glomerular function]. Biochemical assay performed to measure Myeloperoxidase activity [MPO], interlukin-6 [IL-6] as an indicator of inflammation, malondialdhyde [MDA] as an index of lipid peroxidation and C-reactive protein [CRP] level "acute phase protein level The blood sampling for those biochemical studies was withdrawn after induction of anesthesia [t[0]], them 10 min [t[10]], and 30 mm [t[30]] on bypass, at the end of surgery [t[end]] and after 6h [t[6h]] and 24h [t[24h]] after cessation of CPB. There was no significant differences between both group regarding operative, and post operative data except for the duration of ICU stay which was significantly longer in the placebo group MPO activity was significantly higher levels in placebo group compared with the study group starting from t[0] and throughout the study. P=0.001 at t[0]], [t[10]], [t[30]], t[end], t[6th] and t[24h] In addition, its activity had not returned to the preoperative level at 24h P=0.0, while in the study group there was no significant difference in MPO activity at and 24h after cessation of CPB. MDA value started to increase 10 min after commencement of CPB in the placebo compared with the study group, and remained significantly higher throughout the study. P=.03,.02, .001, .01, .01 at t[10], [t[30]], t[end], t[6th] and t[24h] respectively. Similar to the MPO, MAD value had not returned to the preoperative level at t 24h in the placebo group P=.00 Regarding IL-6 levels. The study group patients had significantly lower levels than the placebo at the periods of t30, tend, and t6h. P=.03,.00,.00 respectively. However, 24h after cessation of CPB, the IL-6 levels were similar in both groups. CRP also increased significantly in the placebo group starting 30 mm after commencement of CPB and throughout the study duration P=.001,. 001, .02, .001 at t[end], t[6th] and t[24h] time periods respectively. However CRP levels had not returned to the basal levels in both study and placebo groups after 24h of CPB cessation P=.001. In the placebo group, serum creatinine SC increased significantly from 0.69 +/- 0.32 mg/dL tol.25 +/- 0.33 mg/dL24h after cessation of CPB. P=.001. While the study group showed no significant ehange in its level. Moreover after 24h of CPB cessation the placebo group had significantly higher SC level than the study group .P=.001, In addition to SC elevation in the placebo group, creatinine clearance CC also significantly decreased after 24h compared to the basal value. P=.01, and similar to SC, CC decreased significantly in the placebo group after 24h compared to the study group P=.02. In conclusion, we believe that preioperative administration of NAC has a beneficial protective effect against renal injury induced by ischemia reperfusion due to CBP particularly in patients with normal preoperative renal function

Video-assisted thoracoscopic versus transsternal thymectomy for myasthenia gravis: our early experience

Thymectomy is an accepted surgical modality of therapy for patients with myasthenia gravis. This study aimed at examining the thoracoscopic and transsternal approaches and to compare their surgical outcomes. A prospective cohort study of twenty patients with myasthenia gravis who underwent thymectomy between November 2003 and October 2004. Ten patients [50%] had thoracoscopic surgery while the other ten patients underwent resection by the transsternal route. The patients were followed up for twelve months. Statistical significance was determined by the Student t test or the Fisher's Exact Test. The thoracoscopic group had a mean operating time of 65.5 minutes compared to 76.3 minutes in the transsternal group [P=0.004]. The mean postoperative tube drainage was 54.5 mIs in the thoracoscopic group while it was 118.3 mls in the transsternal group [P=0.0001]. Surgical site infection was the most common complication in the transsternal group occurring in 30% of patients compared to 0% in the thoracoscopic group [P=0.05]. While four patients in the thoracoscopic group [40%] were in remission at 12 months, there were three [30%] in the transsternal group though this was not significant [P=0.23]. Thymectomy through the thoracoscopic approach is a safe and prefecred option for non-thymomatous myasthenia gravis as well as for very small encapsulated thymomas due to the shorter operating time, low complication rates and shorter hospital stay. However, both thoracoscopic and the transsternal routes achieved similar response rates in the short-term

Conversion from off- pump to on-pump coronary surgery: analysis of predictors and early outcome

Off pump coronary bypass [OPCAB] surgery is being increasingly performed to eliminate the morbidity associated with cardiopulmonary bypass [CPB]. One of the limitations of beating heart surgery is that in some instances the procedure cannot be completed safely. The most common reasons for conversions to CPB include: haemodynamic instability with manipulation of the heart, global ventricular ischemia, inability to visualize a target vessel due to deep intramuscular course of target vessel, electrical instability, cardiac arrest and hemorrhage. The aim of this work is to determine: [1] preoperative variables that might identify those patients at greater risk for requiring conversion to on-pump CABG. [2] morbidity and mortality of patients requiring off-pump to on-pump conversion compared with patients having completed off-pump, or on-pump CABG A retrospective study from January 2001 through 2006,on 456 consecutive isolated coronary bypass grafting were performed at king Fahad Armed Force Hospital with the intention to treat all patients with OPCAB, 37 of them had been The 4 surgeons in our series were divided into three groups high volume surgeons [n=2], who had each performed 252,and 130 off-pump procedures; moderate-volume [n=1] who had performed 53 cases, and low-volume surgeons [n=I] who had performed 24 cases. The overall incidence of conversion was 8.3% [n=37/456], in high prior volume of OPCAB had conversion rate of 5.9% which is statistically lower than the rate of low volume surgeon 12.5% [<0.001] .The annual incidence of emergency conversions decreased from 15.1% [n=12/79] to 6.7% [n=8/104], 6% [n=9/150], and 6.2% [n=5/83] for the first to the fifth year of experience, respectively. There is exceptional increase at the fourth year to 28.8% when OPCAB volume was the lowest [8/31]. There were significantly higher numbers of patients with lower left ventricular ejection fraction previous myocardial infarction, COPD patients with emphysematous chest, and more obese patients with higher body mass index [BMI] in converted patients compared with the non-converted patients. Most of our converted patients underwent conversion during grafting circumflex artery [15/37, 40.5%], or during grafting left anterior descending artery in 10 converted to on-pump CABG[8.1%]. patients [27.02%], only one patient converted during grafting right coronary artery [RCA], five patients [13.5%] converted after completion of all distal anastomoses. Six patients were converted electively before any attempt for grafting, specifically during assessment of the anatomy of the heart and coronary vessels, two had small caliber native artery and last one showed dilated myocardium. More than 75.6% of our patients had been converted due to haemodynamic instability [n=28/37]. The second group of conversion reason was electrical disturbances [8.1%, 3/37], the last group of conversion reason was anatomic difficulty [16.2%], 6/37]. Patients who requfred conversion to CPB had significantly higher major morbidities and in-hospital mortality compared with unconverted group 10.8% [4/37] versus 2.3% [1 0/419]. Urgency for conversion was a significant factor in patient death. Patients converted electively had 0% [0/16] mortality which was comparable to that of non converted group, whereas it increases to 12.9% [4/31] in those undergoing urgent emergent conversion. Emergency conversion to CPB during attempt to OPCAB results in a significantly higher morbidity and mortality especially in urgent-emergent situation. COPD, mild-moderate mitral regurge, recent MI, poor EF and obesity are risk factors for emergency conversion. The incidence of conversion decreases with the increasing experience of surgeons in performing OPCAB together with use of cardiac positioning devices