Commencement Of Cardiopulmonary Bypass Research Articles

Perioperative Serum Free Hemoglobin and Haptoglobin Levels in Valvular and Aortic Surgery With Cardiopulmonary Bypass: Their Associations With Postoperative Kidney Injury

To observe the perioperative free hemoglobin and haptoglobin levels and to assess their associations with the risk of postoperative acute kidney injury (pAKI) in adult patients undergoing valvular and aortic surgery requiring cardiopulmonary bypass (CPB). A single-center, prospective, observational study. Public teaching hospital. The study comprised 74 adult patients without chronic renal failure who underwent cardiovascular surgery requiring CPB from 2014 to 2020. Perioperative free hemoglobin and haptoglobin levels during the study period were obtained from study participants. The primary outcome was pAKI defined by the Kidney Disease: Improving Global Outcomes criteria. Of the 74 patients in this study, pAKI occurred in 25 patients (33.8%). The free hemoglobin level began to increase after the initiation of CPB and reached a peak level at 30 minutes after weaning from CPB. It returned to the baseline level on postoperative day one. Haptoglobin levels were the highest after anesthesia induction and decreased continuously until postoperative day one. In the multivariate analysis, maximum free hemoglobin and minimum haptoglobin were associated independently with increased risk of pAKI (adjusted odds ratio 1.33 [95% confidence interval 1.12-1.58; p = 0.001] and 0.95 [95% confidence interval 0.91-1.00; p = 0.03], respectively). The free hemoglobin level began to have an independent association with pAKI at one hour after commencement of CPB, and the independent association disappeared at postoperative day one. This study found that the perioperative increase of the free hemoglobin level and the decrease of the haptoglobin level had independent associations with the risk of pAKI.

Novel use of new parameters in nirs cerebral oximetry in cabg surgery to display changes in brain perfusion

Introduction The use of near-infrared spectroscopy (NIRS) to monitor continuous rSO2 values for the brain is well established (1,2). However the separation of oxygenated & deoxygenated components of NIRS is novel. We report a case of these parameters in CABG surgery. Methods A 68 year old diabetic male underwent CABG. Anaesthesia was induced with etomidate, fentanyl and rocuronium and maintained with air oxygen and isoflurane to a sedation index of 30. The surgery proceeded uneventfully. Some new observations were noted: The effect of increased CMRO2 and rising PSI: At 1042 the effect of increased EEG activity and MAP (85mmHg) leads to a rise in the Sedline PSI which increases delta O2HBi as the oxygen requirements of cerebral activity increase. Autoregulation in vivo. Venous (IVC) and aortic cannulation take place uneventfully cardiopulmonary bypass is commenced at 1052. Effect of CPB, hemodilution and non pulsatile flow: As flow switches from pulsatile to non pulsatile flow and CPB starts, there is an immediate reaction in the delta cHbi values. Haemodilution takes place as pump prime enters the circulation, so the haematocrit falls. O3 values fall but we see a large decrease in delta cHbi because of a reduction in delta O2Hbi as clear pump prime is being administered. Then as oxygenated blood from the CPB pump enters the circulation the delta cHbi recovers as oxygenated blood returns to the head. Note the marked reduction in cHbi and delta O2Hbi values that remains throughout subsequently, and which never recovers. This is the effect of non pulsatile blood flow and the effect it has on cerebral autoregulatory capacity. At this point the MAP is 78. Results: Discussion Principles of NIRS: As oxygenation in cerebral tissue changes, the wavelengths of light absorbed by tissue also change, forming the basis for measurement of regional cerebral oxygen saturation, rSO2. With these indices, we can display information about the changes in the underlying components calculating rSO2 values. δO2Hb is an index representing changes in the oxyhemoglobin component of rSO2. δHHb is an index representing changes in the deoxyhemoglobin component of rSO2. These indices provide visibility into changes in underlying oxyhemoglobin and deoxyhemoglobin components of rSO2. The relative contribution of each component to a patient's overall rSO2 was observed and the use of these additional monitoring indices may allow earlier detection of changes in the blood supply to the brain such as during commencement of cardiopulmonary bypass and the effects of raised CMRO2 and its effects on flow, and hence allow earlier corrective intervention. This may be of value in preventing impending cerebral injury in those patients who may be susceptible.

Multimodal Cardiopulmonary Bypass Skills Assessment Within a High-Fidelity Simulation Environment

A high-fidelity simulator that uses a perfused porcine heart, cannulae, and tubing has been demonstrated to be a useful training adjunct. We hypothesized that multimodal assessment of cardiopulmonary bypass (CPB) skills within this high-fidelity simulated environment could discern expert from trainee performance. Three traditional fellows (postgraduate year 6-8) and 3 attending surgeons each performed 3 aortic cannulations. The third sequence included venous cannulation, commencement of CPB, and placement of a cardioplegia catheter and aortic cross-clamp. Performance across 20 cognitive and 21 technical domains was evaluated. Surgeon and assistant hand movements and economy of motion were assessed by electromagnetic motion sensors worn under sterile gloves. Analysis showed a significant difference in cognitive (6.7 ± 2.3 vs 4.6 ± 2.7, P= .03) but not technical (6.2 ± 2.5 vs 5.8 ± 2.2, P= .7) scores favoring the experts. In addition, experts showed higher efficiency by spending 64 ± 14 seconds to construct a nonpledgeted aortic purse-string suture and secure it with a Rummel, while trainees spent 82 ± 30 seconds to complete this task (P= .03). Motion analysis revealed similar path lengths between experts and trainees for cannulation and CPB but significantly shorter path lengths for experts in cross-clamp (47.5 ± 15.5 m vs 91.9 ± 20.3 m, P= .04). Multimodal assessment using cognitive, technical, and motion analysis of basic CPB tasks using a high-fidelity simulation environment is a valid system to measure performance and discriminate experts from trainees. This construct may allow for development of "competence thresholds" with important implications for training and certification in cardiothoracic surgery.

Effect of oxygen content on postoperative cognitive dysfunction in patients undergoing open-heart surgery

Introduction: Brain's decreased oxygen delivery is proposed as a risk factor for postoperative cognitive dysfunction (POCD). This study's objective was to investigate the effect of arterial oxygen content (CaO2) on POCD in patients undergoing open-heart surgery. Subjects and Methods: Adult patients listed for elective open-heart surgery at Cipto Mangunkusumo General Hospital were enrolled. The patients' cognitive function was tested using the Rey Auditory Verbal Learning Test, trail-making test, and digit span test (forward–backward) before and 5 days after surgery. The hemoglobin level, arterial saturation (SaO2), and arterial oxygen partial pressure (PaO2) were measured at the following five time points: before induction, 10 min after the commencement of cardiopulmonary bypass (CPB), 10 min after the cessation of CPB, 6 h postoperatively, and 1 day postoperatively. The CaO2 was calculated as follows: CaO2= 1.36 × hemoglobin × SaO2 + 0.003 × PaO2. Data were compared using Student's t-test or the Mann–Whitney test with SPSS software version 20.0 (IBM Corp., Armonk, NY, USA). Results: POCD was found in nine patients (47.4%). The CaO was significantly lower in patients with POCD than those without POCD at 10 min after the cessation of CPB (12.1 ± 2.6 vs. 14.5 ± 1.7, respectively; P = 0.03). The hemoglobin level appeared to be the cause of the decreased CaO2 in the POCD group (8.5 ± 2.3 vs. 10.2 ± 1.2, P = 0.06). Decreased oxygen content after CPB cessation may impair brain tissue oxygenation that causes POCD. Conclusion: Hemoglobin level may play an important role in POCD development after open-heart surgery.

Factors that confound the prediction of renal medullary oxygenation and risk of acute kidney injury from measurement of bladder urine oxygen tension.

Urinary oxygen tension (uPO2 ) may provide an estimate of renal medullary PO2 (mPO2 ) and thus risk of acute kidney injury (AKI). We assessed the potential for variations in urine flow and arterial PO2 (aPO2 ) to confound these estimates. In 28 sheep urine flow, uPO2 , aPO2 and mPO2 were measured during development of septic AKI. In 65 human patients undergoing cardiac surgery requiring cardiopulmonary bypass (CPB) uPO2 and aPO2 were measured continuously during CPB, and in a subset of 20 patients, urine flow was estimated every 5minutes. In conscious sheep breathing room air, uPO2 was more closely correlated with mPO2 than with aPO2 or urine flow. The difference between mPO2 and uPO2 varied little with urine flow or aPO2 . In patients, urine flow increased abruptly from 3.42±0.29mL min-1 to 6.94±0.26mL min-1 upon commencement of CPB, usually coincident with reduced uPO2 . During hyperoxic CPB high values of uPO2 were often observed at low urine flow. Low urinary PO2 during CPB (<10mm Hg at any time during CPB) was associated with greater (4.5-fold) risk of AKI. However, low urine flow during CPB was not significantly associated with risk of AKI. uPO2 provides a robust estimate of mPO2 , but this relationship is confounded by the simultaneous presence of systemic hyperoxia and low urine flow. Urine flow increases and uPO2 decreases during CPB. Thus, CPB is probably the best time to use uPO2 to detect renal medullary hypoxia and risk of post-operative AKI.

Cardiopulmonary bypass prime composition: beyond crystalloids versus colloids.

In the literature addressing cardiopulmonary bypass (CPB) prime composition, there is a considerable lack of discussion concerning plasma osmolality changes induced by using a hyperosmolar prime. With this study, we try to determine the magnitude and temporal relationship of plasma osmolality changes related to the use of a hyperosmolar CPB prime. In this prospective observational study performed in a university hospital setting, we enrolled thirty patients scheduled for elective coronary bypass surgery. Plasma osmolality was analysed on eight occasions. A hyperosmolar CPB prime was used. Analyses of the perioperative plasma osmolality on eight occasions gave the following results: the preoperative osmolality level was normal (297±4 mOsm/kg); a significant increase to 322±17 mOsm/kg (p<0.001) was observed at the commencement of CPB and remained elevated after 30 minutes (310±4 mOsm/kg) and throughout the procedure (309±4 mOsm/kg); the osmolality level returned to 291±5 mOsm/kg on day 1 postoperatively and remained normal the following day (291±6 mOsm/kg). Use of hyperosmolar CPB prime resulted in a dramatic and instant elevation of the plasma osmolality. Rapid changes in plasma osmolality are associated with organ dysfunction (e.g. osmotic demyelination syndrome), therefore, effects on plasma osmolality related to the CPB prime composition should be recognised. Influence on organ function and clinical outcome warrants further investigations. - Clinical Trials.gov (NCT03060824). Changes in Plasma Osmolality Related to the Use of Cardiopulmonary Bypass With Hyperosmolar Prime. URL: https://clinicaltrials.gov/ct2/show/NCT03060824?term=cpb&cond=osmolality&rank=1.

A Phase 1 Study of a Novel Bidirectional Perfusion Cannula in Patients Undergoing Femoral Cannulation for Cardiac Surgery

Leg ischemia is a serious complication of femoral artery cannulation. The primary aim of this study was to assess the safety and efficacy of a novel bidirectional femoral arterial cannula (Sorin Group USA, a wholly owned subsidiary of LivaNova PLC, Arvada, CO USA) that provides both antegrade and retrograde flow, in patients undergoing peripheral cannulation for cardiopulmonary bypass during cardiac surgery. Patients undergoing routine cardiac surgery requiring femoral artery cannulation for cardiopulmonary bypass were identified preoperatively. Informed written consent was obtained in all cases. Bidirectional cannula insertion used either a surgical cut-down and wire through needle approach or a percutaneous technique. Flow in the superficial femoral artery was assessed using Doppler ultrasound after commencement of cardiopulmonary bypass. Lower limb perfusion was assessed using reflectance near-infrared spectroscopy to measure regional oxygen saturations in the cannulated limb during cardiopulmonary bypass. Fifteen patients (median age = 61.3 years, range = 26-79 years, 10 males, 5 females) underwent femoral arterial cannulation using the novel bidirectional femoral cannula between August 2016 and May 2017. Fourteen cannulae were inserted directly into the femoral artery via a surgical cut-down and wire through needle technique. One bidirectional cannula was inserted using a percutaneous insertion technique. Indications included minimally invasive mitral and aortic valve surgery, thoracic aortic aneurysm repair, and redo cardiac surgery. The median duration of cardiopulmonary bypass was 129 minutes (range = 53-228 minutes). The cannula was inserted and positioned without difficulty in 14 of 15 patients. Incorrect sizing and arterial spasm prevented correct cannula positioning in one patient. Antegrade flow in the superficial femoral artery was observed on Doppler ultrasound in 12 of 12 patients in which this was performed. Continuous stable distal perfusion was demonstrated in the cannulated limb in 14 of 15 patients. No procedural complications occurred in the immediate or convalescent postoperative period. This study demonstrates that in patients undergoing femoral arterial cannulation for cardiopulmonary bypass during cardiac surgery, the use of a novel bidirectional cannula is safe and easy to insert and provides stable distal perfusion of the cannulated limb. Use of the device should largely obviate the need to insert a separate downstream perfusion cannula or use other techniques to protect against lower limb ischemia. Further research on a larger scale and in different patient populations is now warranted.

Bedside Assessment of the Microvascular Venous Compartment in Cardiac Surgery Patients With Valvular Diseases Undergoing Cardiopulmonary Bypass

Blood volume reserve for venous return and the effects of cardiopulmonary bypass (CPB) on microvascular bed partitioning and blood flow were examined in patients with valvular diseases. Prospective, consecutive, case-control study. Single university hospital. The study comprised 20 adult cardiac surgery patients and 20 healthy volunteers. Cardiovascular and microvascular variables were collected soon after the induction of anesthesia, after commencement of CPB, 20 minutes after separation from CPB, and in the intensive care unit. The unstressed and stressed volumes (Vu, Vs) and pressures therein (Pit, Ps) were measured in the brachioradial muscle with near-infrared spectroscopy, applying incremental venous occlusions. At the first time point, Vs and Pit showed lower and higher values, respectively, than those of control patients, but Vs increased with Vu during the study, whereas Pit remained unchanged. Fluid balance correlated with Pit (r = 0.83, p<0.001) and hemoglobin (r = 0.78, p = 0.004). A nonlinear regression was found between fluid balance and ΔVu (r = 0.90, p<0.001) [y = 1.85+37.43(-0.01×x)]. The Vu/Pit and Vs/Ps ratios were lower than those of the control patients. Blood flow correlated to Vs/Ps (r = 0.75, p<0.001). The time constant was lower than reference (p = 0.005) and increased 10 times after CPB. Cardiac surgery patients have a limited blood volume reserve for venous return due to a reduced microvascular bed capacitance. This study demonstrated that during CPB a positive fluid balance induced an extravascular pressure increase and further reduced blood volume reserve.

Role of a perfusionist in patient blood management

Perfusionists are essential members of the cardiac surgery team. They provide cardiopulmonary support for patients undergoing various cardiac surgeries with the use of the cardiopulmonary bypass (CPB) machine. This takes over the functions of a patient's native heart and lungs. Blood from the patient is drained (typically from the right atrium) into the CPB circuit where it gets oxygenated and then pumped back to the patient's aorta. It is important that the extracorporeal circulation of the CPB meets the oxygen demands of the patient. Central in this oxygen demand–supply relationship between the patient and CPB is blood and its components. Cardiac surgery involves many situations that may necessitate transfusion of blood products. CPB and its circuit components, albeit vital, are one of the major contributors to transfusion. It represents the single largest acute source of exogenous non‐hemic volume infused into a patient at the commencement of CPB. Anticoagulation is also fundamental due to the foreign surfaces of CPB. Systemic cooling of the patient on CPB is another contributor of transfusion. At the National University Hospital, Singapore, measures, both in terms of practices and devices, have been put in place to minimize transfusion. Switching to albumin prime and maintaining mild hypothermia may help reduce prime‐ and hypothermia‐induced coagulopathy. Additionally, devices such as the haemofilter and cell saver can aid in concentrating and recycling patient's own shed blood. Despite each having its own limitations, together, they help to minimize patients receiving homologous blood in the course of their surgery.

Effect of additional preoperative administration of the neutrophil elastase inhibitor sivelestat on perioperative inflammatory response after pediatric heart surgery with cardiopulmonary bypass.

Cardiopulmonary bypass (CPB) elicits a systemic inflammatory response. Our previous reports revealed that prophylactic sivelestat administration at CPB initiation suppresses the postoperative acute inflammatory response due to CPB in pediatric cardiac surgery. The purpose of this study was to compare the effects of sivelestat administration before CPB and at CPB initiation in patients undergoing pediatric open-heart surgery. Twenty consecutive patients weighing 5-10 kg and undergoing ventricular septal defect closure with CPB were divided into pre-CPB (n = 10) and control (n = 10) groups. Patients in the pre-CPB group received a 24 h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the induction of anesthesia and an additional 0.1 mg/100 mL during CPB priming. Patients in the control group received a 24-h continuous intravenous infusion of 0.2 mg/kg/h sivelestat starting at the commencement of CPB. Blood samples were tested. Clinical variables including blood loss, water balance, systemic vascular resistance index, and the ratio between partial pressure of oxygen and fraction of inspired oxygen (P/F ratio) were assessed. White blood cell count and neutrophil count as well as C-reactive protein levels were significantly lower in the pre-CPB group according to repeated two-way analysis of variance, whereas platelet count was significantly higher. During CPB, mixed venous oxygen saturation remained significantly higher and lactate levels lower in the pre-CPB group. Postoperative alanine aminotransferase and blood urea nitrogen levels were significantly lower in the pre-CPB group than in the control group. The P/F ratio was significantly higher in the pre-CPB group than in the control group. Fluid load requirement was significantly lower in the pre-CPB group.Administration of sivelestat before CPB initiation is more effective than administration at initiation for the suppression of inflammatory responses due to CPB in pediatric open-heart surgery, with this effect being confirmed by clinical evidence.

Comparison of Cardioprotective Effects of Volatile Anesthetics in Children Undergoing Ventricular Septal Defect Closure

Volatile anesthetic agents may precondition the myocardium and protect against ischemia and infarction. Preconditioning by volatile anesthetic agents is well documented in adults but is underinvestigated in children. The present study compares the effect of preconditioning in children by three volatile anesthetic agents along with several other variables associated with cardioprotection. Eighty children scheduled for ventricular septal defect closure under cardioplegic arrest were assigned to preconditioning for five minutes after commencement of cardiopulmonary bypass (CPB) with one minimum alveolar concentration (MAC) of one of the following agents: isoflurane, sevoflurane, desflurane, or placebo (oxygen-air mixture). The plasma concentration of creatine kinase MB (CK-MB) was determined after initiation of CPB, and again 6 and 24 hours after admission to the intensive care unit (ICU) after surgery. Duration of inotropic support, mechanical ventilation, and length of ICU stay in all the groups were also recorded. Preconditioning with isoflurane, sevoflurane, and desflurane was associated with significantly decreased postoperative release of CK-MB as compared to placebo group at 6 (group 1: 237.2 ± 189, group 2: 69.8 ± 15.8, group 3: 64.7 ± 37.8, and group 4: 70.4 ± 26.7) and 24 hours (group 1: 192.4 ± 158.2, group 2: 67.7 ± 25.0, group 3: 85.7 ± 66.8, and group 4: 50.4 ± 31.6) after admission to ICU. No significant differences were observed in the CK-MB levels among the three volatile anesthetic agents. Duration of inotropic support, mechanical ventilation, and length of ICU stay were greater in placebo group as compared to other groups without reaching statistical significance. Volatile anesthetic appear to provide definite cardioprotection to pediatric myocardium. No conclusion can be drawn regarding the best preconditioning agent among isoflurane, sevoflurane, and desflurane.

Effect of ulinastatin on perioperative organ function and systemic inflammatory reaction during cardiac surgery: a randomized double-blinded study

BackgroundThis study evaluated the efficacy of ulinastatin for attenuating organ injury and the release of proinflammatory cytokines due to cardiopulmonary bypass (CPB) during cardiac surgery.MethodsPatients undergoing valvular heart surgery employing CPB were assigned to receive either ulinastatin (group U, n = 13) or a placebo (group C, n = 11) before the commencement of CPB. Hemodynamic data, parameters of major organ injury and function, and proinflammatory cytokines were measured after the induction of anesthesia (T1), after CPB (T2), at the end of anesthesia (T3), and at 24 hours after surgery (POD).ResultsThe demographic data, CPB duration, and perioperative transfusions were not different between the groups. PaO2/FiO2 in group U was significantly higher than that in group C at T3 (3.8 ± 0.8 vs. 2.8 ± 0.7, P = 0.005) and at POD (4.0 ± 0.7 vs. 2.8 ± 0.7, P < 0.001). Creatine kinase-MB at POD in group U was significantly lower than that in group C (17.7 ± 8.3 vs. 33.7 ± 22.1, P = 0.03), whereas troponin I at POD was not different between the groups. Creatinine clearance and the extubation time were not different between the groups at POD. The dopamine infusion rate during the post-CPB period in group U was significantly lower than that in group C (1.6 ± 1.6 vs. 5.5 ± 3.3 µg/kg/min, P = 0.003). The interleukin-6 and tumor necrosis factor-α concentrations at T1, T2, and T3 as well as the incidences of postoperative cardiac, pulmonary and kidney injuries were not different between the groups.ConclusionsUlinastatin pretreatment resulted in an improved oxygenation profile and reduced inotropic support, probably by attenuating the degree of cardiopulmonary injury; however, it did not reduce the levels of proinflammatory cytokines.

Protective effect of epicardial adiponectin on atrial fibrillation following cardiac surgery

Inflammation has been implicated in the pathogenesis of postoperative atrial fibrillation (AF). Adipose tissue secretes both pro-inflammatory cytokines such as interleukin-6 (IL-6) and anti-inflammatory mediators such as adiponectin. We set out to examine the association of adiponectin and IL-6, both circulating and locally produced by the epicardial adipose tissue, with AF development after cardiac surgery. A total of 90 consecutive patients undergoing cardiac surgery were evaluated. Blood samples were collected before induction of anaesthesia. Epicardial fat was obtained upon commencement of cardiopulmonary bypass. IL-6 and adiponectin levels were determined in serum and supernatant of epicardial adipose tissue organ cultures with two-site enzyme-linked immunosorbent assay (ELISA). Heart rhythm was assessed with continuous tele-monitoring for 72 h postoperatively, and with 6-hourly clinical examinations and daily electrocardiograms (ECGs) thereafter. A total of 36 patients developed postoperative AF (40%). Baseline-serum IL-6 and adiponectin were not associated with AF (p = 0.86 and 0.95, respectively). Epicardial adipose tissue IL-6 levels did not correlate with the development of the arrhythmia either (p = 0.37). However, epicardial adiponectin release was lower in patients who developed AF than in those who remained in sinus rhythm (76 (interquartile range (IQR) 35-98) vs 53 ((IQR) 35-69) ng h(-1)g(-1) of tissue cultured, p = 0.066). Following linear regression, the association of epicardial adiponectin with AF almost reached statistical significance (p = 0.066). Multivariate logistic regression analysis of identified risk factors for AF, with the inclusion of epicardial adiponectin as an independent variable, revealed increased age (odds ratio (OR) 1.09, 95% confidence interval (CI) 1.02-1.17, p = 0.013) and epicardial adiponectin levels (OR 0.98, 95% CI 0.97-1.00, p = 0.054) as independent predictors of postoperative AF. Increased epicardial adiponectin is associated with maintenance of sinus rhythm following cardiac surgery. This reinforces the inflammatory hypothesis in the pathogenesis of postoperative AF and may represent a novel therapeutic target for its effective prevention.

Methylene Blue for CPB

To the Editor: Maslow et al. (1) explored the beneficial effects of methylene blue on mean arterial pressure during and after cardiopulmonary bypass (CPB). We were intrigued, however, by the fact that methylene blue was administered after an initial period of stabilization on bypass (5 min). As shown in the past, hypotension during CBP is independently associated with postoperative morbidity (2) Hypotension is also an independent predictor of mortality for noncardiac surgery (3). It would be more logical to administer the hypotension-avoiding agent prior to the hypotensive insult, commencement of CPB in the present case. The logistics of infusing methylene blue prior to CPB would not be a problem as methylene blue infusions over 15 min durations have not been documented to cause hypotension (4). It would be interesting to know if a trial with methylene blue administered prior to CPB would also reduce postoperative morbidity. Dr. K. Valchanov, MD Dr. F. Falter, MD Department of Anaesthesia Papworth Hospital Cambridge CB3 8RE, UK [email protected]

Methylene blue revisited: Management of hypotension in a pediatric patient with bacterial endocarditis

Clinical Summary A 10-year-old girl, weighing 32 kg, with no medical history was transferred from a regional center with Staphylococcal aureus native mitral valve endocarditis complicated by cerebral infarction and hemorrhage in both frontal lobes, the right thalamus, and possibly the left caudate nucleus and thalamus. She deteriorated day 2 of admission with chorda rupture, and an emergency mitral valve operation was indicated. Standard anesthesia was administered. Preanesthesia inotropes were dopamine 10 g · kg 1 · min 1 and epinephrine 0.5 g · kg 1 · min . A bolus dose of 2 mg/kg of methylene blue was given. On commencement of cardiopulmonary bypass, a further 2 mg/kg and an infusion of 1 mg · kg 1 · h 1 of methylene blue was commenced. An abscess around the mitral valve annulus was resected and replaced with a porcine valve. The dilated left atrium and ventricle were reinforced with a bovine pericardial patch. During bypass, mean arterial pressure was maintained between 30 and 40 mm Hg. Cerebral oximetry ranged from 76% to 93% prebypass during methylene blue infusion and from 66% to 82% during bypass. Surprisingly, methylene blue did not seem to affect oximetry readings. The CPB time was 133 minutes, and the aortic crossclamp time was 115 minutes. Weaning from bypass required epinephrine 0.05 to 0.1 g · kg 1 · min , norepinephrine 0.1 g · kg 1 · min , vasopressin 0.0001 to 0.0003 g · kg 1 · min , milrinone 0.33 g · kg 1 · min , and methylene blue infusion at 1 mg · kg 1 · h 1 to achieve a systolic arterial pressure of 70 to 80 mm Hg and diastolic pressure range of 30 to 50 mm Hg. The patient was transferred to the critical care unit and extubated 6 days later. The methylene blue infusion was ceased on arrival to the unit. Epinephrine and norepinephrine were ceased the day after surgery, vasopressin was ceased on postoperative day 2, and milrinone was ceased on day 8.

An Evaluation of the Effects of a Standard Heparin Dose on Thrombin Inhibition During Cardiopulmonary Bypass in Neonates

We compared the adequacy of heparinization in neonates and older children undergoing cardiopulmonary bypass (CPB) by measuring heparin activity, thrombin formation, and thrombin activity. Ten neonates and 10 older children were administered 400 U/kg of heparin before CPB. Heparin anti-Xa activity, prothrombin fragment 1.2 (F1.2), and fibrinopeptide A (FPA) were measured at baseline, after 30 min on CPB, immediately post-CPB, and 3 and 24 h post-CPB. Heparin anti-Xa activity was significantly decreased during and immediately post-CPB in the neonatal group. F1.2 and FPA levels in neonates were significantly higher at baseline, decreased with the commencement of CPB, and increased to levels higher than those in older children after CPB. Our data show that with standard heparin doses, neonates exhibit less heparin anti-Xa activity during CPB. Higher baseline levels of F1.2 and FPA present in neonates indicate preoperative activation of their coagulation systems as compared with older children. Although F1.2 and FPA levels initially decrease with the commencement of CPB, probably representing hemodilution, the subsequent increase in these markers indicates significantly more thrombin formation and activity during and after CPB. These results raise the concern that 400 U/kg of heparin may not adequately suppress thrombin formation and activity in neonates undergoing CPB.

Perioperative melatonin circadian secretion in patients undergoing coronary artery bypass grafting surgery

To investigate the circadian rhythm of perioperative melatonin secretion in patients undergoing coronary artery bypass grafting surgery. Forty male patients scheduled for elective coronary artery bypass grafting surgery (CABG) under hypothermic cardiopulmonary bypass (CPB) or off-pump were allocated into two groups of 20 patients: CPB group and off-pump group. Blood samples were withdrawn from all patients immediately before the induction of anesthesia (baseline), 10 min after the induction of anesthesia, 10 min after heparinization, 30 min after commencement of CPB (or 2h after skin incision), before reversal of heparin with protamine, at the end of surgery, and. every 3 hours after operation until the twenty-fourth hour. The plasma concentration of melatonin was measured by using enzyme-linked immunosorbent assay. The plasma melatonin concentrations during and after CPB were higher than the baseline value in the CPB group. There were no differences in the melatonin concentrations in the off-pump group. In the CPB group the melatonin concentrations after induction, during CPB, and after CPB were 7.2 +/- 3.4, 10.5 +/- 5.2, and 9.5 +/- 4.0 respectively, all significantly higher than those in the off-pump (5.5 +/- 2.5, 6.3 +/- 2.0, and 5.7 +/- 2.1 respectively, all P < 0.05). During the twenty-four hours after operation, two patients in the CPB group and six patients in the off-pump group showed circadian rhythm of melatonin secretion. The perioperative circadian rhythm of melatonin secretion in patients undergoing CABG surgery with CPB or off-pump is disturbed, however relatively more patients under off-pump group regain secretion rhythm of melatonin in the immediate postoperative period. CPB may be one of the reasons for perioperative melatonin circadian secretion disturbance.

Pharmacokinetics of intravenous flucloxacillin and amoxicillin in neonatal and infant cardiopulmonary bypass surgery.

To determine the blood and tissue concentrations of flucloxacillin and amoxicillin during cardiopulmonary bypass (CPB) in infants weighing less than 5 kg. Eleven patients aged between 3 and 60 days and weighing <5 kg. Intravenous flucloxacillin 30 mg kg(-1) and amoxicillin 30 mg kg(-1) were administered at time of anaesthesia. Blood and muscle samples were collected at four stages of the operation: immediately before commencement of CPB; before cross-clamping; after weaning of CPB; and at the time of skin closure. Concentrations, half-lives (t(1/2)), clearance and volume of distribution were calculated for both antibiotics in serum and tissue. After connection to CPB the mean serum concentration of flucloxacillin decreased by 42.5% from 75.5 to 43.4 mg l(-1) (P=0.003) and that of amoxicillin decreased by 36.2% from 73.3 to 46.7 mg l(-1) (P=0.021). Serum concentrations of the two antibiotics decreased by a further 16.5 and 14.5% during the remainder of the surgery, but remained >15-fold above the expected minimum inhibitory concentration (MIC) for target pathogens. Muscle concentrations of both antibiotics reached MIC values by the time of the first sample and there was no decrease associated with connection to CPB. Levels remained >8-fold above MIC for target pathogens throughout the procedure. The t(1/2) for flucloxacillin was 2.64(+/-0.23)h and for amoxicillin was 3.16(+/-0.29)h, both of which are more than double the values in normal adults. There was an equivalent reduction in clearance for both antibiotics. Single doses of flucloxacillin and amoxicillin at 30 mg kg(-1) maintain serum and muscle concentrations well above the MIC throughout cardiac surgery. This is partly due to a prolonged t(1/2) and reduced clearance of both antibiotics in infants.

Cardiopulmonary bypass is not associated with increased jugular venous blood free radical activity.

We have measured jugular venous oxygen saturation (sjv(O2)) and lactate, arterial and jugular venous blood levels of lipid peroxidation products--malondialdehyde (MDA) and diene conjugates as an index of free radical activity in eight adults undergoing coronary artery bypass surgery. Measurements were carried out at six specific times: T1--within 5 min before cardiopulmonary bypass (CPB), T2--within the first minute after the commencement of CPB, T3--during stable temperature (28 degrees C) on CPB, T4--during rewarming at 34 degrees C, T5--15 min after CPB and T6--at skin closure. There were no significant changes in arterial, jugular venous and arterio-jugular venous (a-jv) differences in diene conjugates and MDA. There was no correlation between sjv(O2), lactate and a-jv differences in MDA and diene conjugates. These results are not indicative of ischaemia-reperfusion injury across the cerebral circulation during hypothermic CPB.

Diagnosis of a unicuspid aortic valve using transesophageal echocardiography

NICUSPID AORTIC VALVE is a rare condition. It is often discovered during surgery or autopsy and can easily be mistaken for a bicuspid aortic valve. Morphologic similarities between unicuspid and bicuspid valves can often make echocardiographic differentiation difficult. However, multiplane transesophageal echocardiography (TEE) has been shown to be superior to transthoracic echocardiography for the diagnosis of aortic valve abnormalities. 1 CASE REPORT The patient was a 38-year-old white man with a history of congenital bicuspid aortic valve and aortic regurgitation. He presented with a 4- to 5-month history of shortness of breath with dyspnea on exertion and a 5-week history of chest pain and dizziness. Cardiac auscultation revealed a regular cardiac rate and rhythm with a 4 over 6 systolic ejection murmur heard best at the right upper sternal border, with radiation to the carotid arteries bilaterally. The remainder of the examination, including the pulmonary examination, was normal. Cardiac catheterization was significant for presumed bicuspid aortic valve with aortic regurgitation. The patient was scheduled for an aortic valve replacement with a pulmonary valve autograft (Ross procedure) versus placement of an aortic homograft. The patient was taken to the operating room where an intra-arterial catheter was placed, and general anesthesia was induced with sodium thiopental and sufentanil and muscle relaxation was initiated with pancuronium. After induction of anesthesia, a 5-MHz Hewlett Packard omniplane transesophageal probe (Hewlett-Packard, Andover, MA) was inserted orally and advanced to the level of the stomach. A full TEE examination was performed including 2-D (two-dimensional), M-mode, color, and Doppler modalities. The 2-D examination revealed mildly reduced left ventricular function with an estimated ejection fraction of 45% to 50%. No segmental wall motion abnormalities were appreciated. In the midesophageal short-axis view, the aortic valve appeared unicuspid as evidenced by a small, eccentric, and posteriorly located orifice (Fig 1). The possibility of a bicuspid valve remained, however, as a fused raphe seemed to appear intermittently during diastole in an anteriorly oriented position (at the 7 o’clock position). In the midesophageal long-axis view, the aortic annulus and aortic root were noted to be severely dilated measuring 35 mm and 56 mm, respectively. The ascending aorta was moderately dilated, and the descending thoracic aorta showed mild atherosclerotic disease. Color Doppler findings were significant for moderateto-severe aortic insufficiency. After commencement of cardiopulmonary bypass, the diagnosis of a unicuspid aortic valve was confirmed on aortotomy. On direct inspection, the valve was found to be unicuspid, markedly redundant, and severely insufficient (Fig 2). The ascending aorta and aortic root were replaced under deep hypothermic circulatory arrest with a composite 29-mm Hemashield Dacron (Boston Scientific, Boston, USA) graft and cryopreserved aortic allograft. The remainder of the surgical procedure was uneventful, and the patient was separated from cardiopulmonary bypass without inotropic support. The postpump TEE revealed a trileaflet, normal functioning aortic allograft with trace regurgitation and a peak valve gradient of 5 mmHg. A follow-up transthoracic echocardiography examination on postoperative day 4 revealed mild left ventricular dilatation and concentric left ventricular hypertrophy, with trace aortic regurgitation. The aortic peak gradient was 5 mmHg with a mean gradient of 3 mmHg. The remainder of the hospital course was uncomplicated, and the patient was discharged home on postoperative day 4 in satisfactory condition. DISCUSSION Unicuspid aortic valve is rare and is often confused with a bicuspid valve, a more common congenital abnormality. In adults undergoing surgical intervention for aortic valve disease, unicuspid valve accounts for 5% of the cases, whereas a bicuspid valve accounts for nearly 36% of the cases. 2-4 Both are usually asymptomatic at birth and in childhood, although they can cause symptoms of stenosis or regurgitation. In early adulthood, when degenerative fibrosis and calcification result in aortic stenosis and, less commonly, regurgitation, the symptomatology between the 2 valvular lesions remains indistinguishable. Syncope, angina, and shortness of breath are common manifestations of outflow obstructive lesions, which include bicuspid and unicuspid aortic valves, subaortic membranes, and idiopathic hypertrophic cardiomyopathy. Accordingly, TEE may be an effective diagnostic tool to distinguish