Mild Hypothermic Cardiopulmonary Bypass Research Articles

Effectiveness of Mild to Moderate Hypothermic Cardiopulmonary Bypass on Early Clinical Outcomes.

Background: Intraoperative hypothermia is an integral part of cardiopulmonary bypass (CPB), and a precise degree of hypothermia may improve the early clinical outcomes of cardiac surgery. Presently, there is no agreement on an accurate, advantageous temperature range for routine use in CPB. To address this issue, we conducted a retrospective observational study to compare the effects of different hypothermic temperature ranges on primary (inotropic support, blood loss, and platelet count) and secondary (ventilation support and in-hospital stay) outcomes in patients undergoing elective cardiac surgery. Methods: Data were retrieved from the medical database of the Cardiovascular Surgery Department, King Edward Medical University, Lahore-Pakistan (a tertiary care hospital), dating from February 2015 to December 2017. Patients were divided into mild (34 °C to 36 °C), intermediate (31 °C to 33 °C), or moderate (28 °C to 30 °C) hypothermic groups. Results: Out of 275 patients, 245 (89.09%) fit the inclusion criteria. The cohort with mild hypothermic CPB temperatures presented better clinical outcomes in terms of requiring less inotropic support, less blood loss, fewer blood transfusions, improved platelet counts, shorter in-hospital stays, and required less ventilation support, when compared with other hypothermic groups. Conclusions: Mild hypothermic CPB (34 °C to 36 °C) may produce better clinical outcomes for cardiac surgery and improve the quality of health of cardiac patients.

Reliability of different body temperature measurement sites during normothermic cardiac surgery.

Patients undergoing cardiac surgery can experience significant thermal changes during the perioperative period and, for that reason, it is essential to monitor temperatures with adequate accuracy and precision during cardiopulmonary bypass (CPB). The primary aim of the current study was to measure the discrepancies between temperatures at different body sites during normothermic or mild hypothermic CPB. 48 patients undergoing cardiac surgery participated in our study. Simultaneous temperatures were measured at nasopharynx, pulmonary artery, arterial outlet, venous inlet, forehead using a heat flux sensor, and urinary bladder at 5-min intervals throughout surgery. The Bland-Altman plot for repeated measures was used to assess concordance between methods. The duration of surgery was 360min (interquartile range (IQR) 300-412), while the median cross-clamp time was 135min (IQR 101-169). During the CPB time, the average difference between arterial outlet and nasopharyngeal temperature was -0.16°C (95% limits of agreement of ±0.93). The bias between arterial outlet and the venous inflow was 0.16°C and the 95% limits of agreement were -0.63 to 0.95°C. The Bland-Altman analysis showed an average difference between oxigenator arterial outlet and bladder probe of -0.62 (95% limits of agreement of ±1.3). The average difference between arterial outlet and Tcore™ temperatures was 0.08°C (95% limits of agreement of ±1.46). 25 patients (52.08%) presented nasopharyngeal temperatures higher than 37°C in the post-CPB period, but none of them exceeded 38°C. Perfusionists should be cautious when using the nasopharyngeal site as the only surrogate of brain temperature, even in normothermic cardiac surgery because the precision of measurements is not entirely adequate.

Del Nido cardioplegia in surgery for aortic root disease: a historically controlled study.

BackgroundTo determine the safely and effectively of del Nido cardioplegia (DNC) in surgery for aortic root disease, with mild hypothermic cardiopulmonary bypass (CPB).MethodsFrom July to December 2017, all patients undergoing the surgery for aortic root disease (total aortic root replacement, valve-sparing aortic root replacement and replacement of aortic valve plus ascending aorta), with mild hypothermic CPB, were retrospectively reviewed at our institution. Patients were divided into two groups based on the type of cardioplegia: the classical blood cardioplegia (CBC group) and del Nido cardioplegia (DNC group). Demographics, operative details, perioperative data and postoperative complications were recorded and compared. A propensity score matching was performed in this study.ResultsThe preoperative data in DNC group were similar to CBC group. The volume of ultrafiltration was lower in DNC than CBC group (2,053.49±806.62 DNC vs. 2,666.00±967.14 CBC, P=0.001), when matched. The use of temporary pacemaker was more in DNC group (n=20, 46.5%, P=0.023), and the rate of automatic heart resuscitating was higher in the CBC group (92.0% vs. 72.1% DNC group, P=0.024, unmatched).There were no differences in in-hospital mortality, troponin T (mean 0.66 ng/mL for CBC group vs. 0.49 ng/mL for DNC group, P=0.152), left ventricular ejection fraction (mean 58.37% for CBC group vs. 60.07% for DNC group, P=0.395) or other postoperative complications between two groups, after matching. In subgroup analysis, the ultrafiltration volume was lower in DNC than CBC group (1,932.26±749.39 DNC vs. 2,640.00±996.24 CBC, P=0.004), when ACC time less than or equal to 90 minutes. The apache score was better in DNC group (4.75±3.41, P=0.041), when ACC time greater than 90 min. There were no statistical significances in other characteristics between groups.ConclusionsDNC is safe and effective for surgery for aortic root disease, not inferior to the CBC.

Aortic uncrossing and tracheobronchopexy corrects tracheal compression and tracheobronchomalacia associated with circumflex aortic arch

ObjectiveAortic uncrossing is an effective procedure for relieving the external airway compression from a circumflex aortic arch by transferring the aortic arch to the same side as the descending aorta. However, patients frequently have residual tracheobronchomalacia (TBM), which may result in persistent postoperative symptoms. We review a series of patients who underwent an aortic uncrossing and concomitant tracheobronchopexy to correct the airway compression and residual TBM. MethodsRetrospective review of all patients who underwent aortic uncrossing and concomitant tracheobronchopexy at a single institution between September 2016 and March 2019. Preoperative evaluation included computed tomography angiography and rigid 3-phase dynamic bronchoscopy. ResultsEight patients who ranged in age from 4 months to 15 years with significant respiratory symptoms underwent an aortic uncrossing procedure with concomitant tracheobronchial procedures. Mild hypothermic cardiopulmonary bypass (mean time, 105.6 ± 39.4 min) and regional perfusion (mean time, 44 ± 10 min) were used without circulatory arrest. Intraoperative bronchoscopy demonstrated no patients had residual TBM. There were no postoperative mortalities, neurologic complications, chylothoraces, coarctations, or obstructed aortic arches. Two patients required tracheostomy and gastrostomy for bilateral recurrent laryngeal nerve paresis (patients 2 and 3). One patient with bronchial stenosis after concomitant slide bronchoplasty required stenting. At a median follow-up of 22 months (range, 5-34 months), all patients were alive without evidence of significant respiratory symptoms. ConclusionsThe aortic uncrossing procedure can be performed safely in pediatric patients of all ages without circulatory arrest. Concomitant procedures addressing associated TBM can significantly improve respiratory symptoms.

Thoracoabdominal aortic replacement for Crawford extent II aneurysm after thoracic endovascular aortic repair

The surgical treatment of Crawford extent II aneurysms after thoracic endovascular aortic repair (TEVAR) remains challenging, because of the need to remove the failed endograft and the complexity of the aortic reconstruction. We retrospectively reviewed our experience with surgical management of Crawford extent II aneurysms after TEVAR using thoracoabdominal aortic replacement (TAAR). Eleven patients (10 males, 1 female) with Crawford extent II aneurysm after TEVAR were treated with TAAR between August 2012 and May 2015. The indications included: diameter >5.0 cm; persistent pain; size increase >0.5 cm/year; and no suitable landing zone for re-TEVAR. Five patients underwent surgery under deep hypothermic cardiac arrest, two under mild hypothermic cardiopulmonary bypass, and four under direct aortic cross-clamping under normothermia. Two patients had Marfan syndrome. There were no in-hospital deaths. Continuous renal replacement therapy was required in three patients. One patient needed re-intubation, and two patients had prolonged intubation (>72 h). One patient sustained paraplegia after surgery but recovered during follow-up. Cerebrospinal fluid drainage were used in four patients (3 immediately in the operation room, and 1 in the intensive care unit when the patient suffered paraplegia). One patient died during follow-up. TAAR represents a feasible option for the treatment of Crawford extent II aneurysms after TEVAR, with acceptable surgical risks and favorable results.

Abstract 20074: Hemodynamic Profile of Prolonged Normothermic, Mild Hypothermic, and Deep Hypothermic Emergency Cardiopulmonary Bypass Reperfusion in Rats

Background: The hemodynamic profile of rats randomized into prolonged normothermic (NT, 37±0.5°C), mild hypothermic (MH, 33±0.5°C) or deep hypothermic (DH, 27±0.5°C) reperfusion with emergency cardiopulmonary bypass (ECPB), following refractory ventricular fibrillation cardiac arrest (VF CA) was explored. Methods: Fifty adult male Sprague-Dawley rats were put on bypass for 15 min, following 10 min of VF CA. The ECPB setup included a circulating water bath which temperature controlled all animals at target. After 15 min, rats were defibrillated, weaned from bypass, and controlled at 33°C (MH, DH) or 37°C (NT) externally. All rats received a single dose of epinephrine (30 μg/kg), heparin and sodium bicarbonate with the crystalloid priming of the ECPB circuit. ECPB flow rate was kept at 100 mL/kg in all groups. Mean arterial pressure (MAP) was continuously monitored in the femoral artery and is presented as median with 25th/75th quartile mmHg. Results: See figure. There was no difference in MAP before or during CA. For the first 5 min of resuscitation, MAP at a given ECPB flow rate was highest in the DH group (DH 84(69;89), MH 51(49;61), NT 48(37;55) , p = <.001). This was reversed during the last 5 min on bypass (DH 35(30;42), MH 44(37;64), NT 42(33;67), p = .034). For 10 min off bypass, the DH group was relatively hypotensive (DH 46(40;62, MH 64(60;77), NT 61(54;77), p = .005), which was again reversed for the remaining post resuscitation period (DH 68(60;78), MH 59(54;66), NT 53(49;62), p = .008). Conclusions: While the temperature profiles of NT and MH reperfusion were similar, DH caused initially higher pressures followed by a period of hypotension as compared to NT and MH groups at identical epinephrine doses and ECPB flow rates. Off bypass, DH animals were again relatively hypotensive, coinciding with their rewarming to mild hypothermia. Further experiments are needed to determine the cause of this, like hypothermic vasoconstriction, or altered pharmacokinetics.

Effects of topical hypothermia on postoperative inflammatory markers in patients undergoing coronary artery bypass surgery.

SummaryBackgroundWe aimed to examine the effects of topical hypothermia on inflammatory markers in patients undergoing coronary artery bypass surgery.MethodsFifty patients undergoing isolated coronary artery bypass surgery were included the study. They were randomised to two groups. Mild hypothermic cardiopulmonary bypass (28–32°C) was performed on both groups using standardised anaesthesiology and surgical techniques. Furthermore, topical cooling with 4°C saline was performed on patients in group I. We recorded peri-operative and intra-operative results of blood samples, pre-operative and postoperative outcomes of electrocardiography and echocardiography, diaphragm levels on X-ray, and the necessity of positive inotropic medication and intra-aortic balloon pump (IABP).ResultsTime-dependent changes in blood samples were compared between the two groups. The changes on complement 3 (C3) and TNF-α levels were more significant in group I than group II (p < 0.05 and p < 0.001, respectively). Spontaneous restoration rate of sinus rhythm was higher in group II than group I (80 vs 32%, p < 0.01). Atrial fibrillation was seen in six patients in group I and one patient in group II (p < 0.05). IABP was performed on four patients (16%) in group I (p < 0.05). Diaphragmatic paralysis was seen in seven patients in group I but not in group II (p < 0.01). Partial pericardiotomy rates were compared within the groups but there was no statistically significant difference (p > 0.05). One patient in group I died on the 18th postoperative day, but operative mortality rate was not statistically significant between the two groups (p > 0.05).ConclusionsTopical hypothermia had a negative impact on inflammatory markers and postoperative morbidities.

Effect of Mild Hypothermic Cardiopulmonary Bypass on the Amplitude of Somatosensory-evoked Potentials

Several neurophysiological techniques are used to intraoperatively assess cerebral functioning during surgery and intensive care, but the introduction of hypothermia as a means of intraoperative neuroprotection has brought their reliability into question. The present study aimed to evaluate the effect of mild hypothermia on somatosensory-evoked potentials' (SSEPs) amplitude and latency in a cohort of cardiopulmonary bypass (CPB) patients as the temperature reached the steady-state. The amplitude and latency of 4 different SSEP signals--N9, N13, P14/N18 interpeak, and N20/P25--were evaluated retrospectively in 84 patients undergoing CPB during normothermic (36°C±0.43°C) and mild hypothermic (32°C±1.38°C) conditions. SSEPs were recorded in normothermia immediately after the induction of anesthesia and in hypothermia as the temperature reached its steady-state, specifically, when the nasopharyngeal temperature was equivalent to the rectal temperature (±0.5°C). A paired-samples t test was performed for each SSEP to test the differences in latencies and amplitudes between normothermic and hypothermic conditions. Compared with normothermia, hypothermia not only significantly increased the latency of all SSEPs, N9 (P<0.001), N13 (P<0.001), P14/N18 (P<0.001), and N20/P25 (P<0.001), but also the amplitude of N9 (P<0.001) and N20/P25 (P<0.001). The increased amplitude in particularly of cortical SSEPs (N20/P25), detected specifically during steady-state hypothermia, seems to support the clinical utility of this methodology in monitoring the brain function not only during cardiac surgery with CPB, but also in other settings like therapeutic hypothermia procedures in an intensive care unit.

Neurological outcome of normothermic versus hypothermic cardiopulmonary bypass in simple congenital heart diseases

Objective We hypothesized that normothermic cardiopulmonary bypass (CPB) may provide equivalent results to hypothermic CPB on neurological outcome. Patients and methods Forty patients were randomized to one of two groups: group 1 that underwent normothermic CPB (>35°C) and group 2 that underwent mild hypothermic CPB (32°C). Perfusion on bypass was performed by a nonpulsatile pump flow with an average flow rate around 2.4 l/m 2 /min. A pH-stat carbon dioxide management strategy was used. The arterial and jugular venous blood gases, mean cerebral blood flow velocity (CBFV), and pulsatile index were measured as basal, after induction of anesthesia, at the onset of CPB, 20-30-40 min after the CPB, at the cessation of CPB, and at the end of the operation. Neurological outcomes were assessed by computed tomography scanning and Wechsler Preschool and Primary Scale of Intelligence preoperatively, at the third postoperative day and 1 month after surgery. Postoperative ICU variables such as duration of mechanical ventilation, time to extubation, and ICU length of stay were recorded. Results There was a significant increase in SjvO 2 and decrease in CeO 2 in the hypothermia group of patients after establishment of hypothermia by 10 and 20 min when compared with the normothermic group ( P 2 was maximal during normothermic CPB and after rewarming phase of hypothermic CPB. There were no significant changes in computed tomography scanning and Wechsler Preschool and Primary Scale of Intelligence between the studied groups at any time period. There was significant prolongation in duration of postoperative mechanical ventilation, extubation time, and duration of ICU stay in the hypothermic group of patients compared with the normothermic group ( P Conclusion During CPB for correction of congenital heart defects, the normothermic and hypothermic CPB were comparable with respect to the neurological outcome. However, normothermia permits shorter time on mechanical ventilation, more rapid extubation, and shorter ICU stay time compared with hypothermia.

Discrete subaortic stenosis diagnosed intraoperatively

To the Editor: Discrete subaortic stenosis (DSS) is an uncommon form of left ventricular outflow tract (LVOT) obstruction characterized by a discrete subaortic membrane (DSM) [1]. We report a case of DSS that was misdiagnosed as valvular aortic stenosis (AS) preoperatively with transthoracic echocardiography (TTE) or cardiac catheterization and correctly diagnosed intraoperatively by careful examination with transesophageal echocardiography (TEE). A 5-year-old boy, who had undergone corrective surgery for coarctation complex in the neonatal period, was scheduled to undergo aortic valve replacement or aortic valve plasty for severe AS. The preoperative diagnosis made by TTE and cardiac catheterization was valvular AS with the peak pressure gradient of 92 mmHg resulting from limited opening of the right coronary cusp (RCC) and moderate aortic regurgitation (AR). Our initial findings with intraoperative TEE after induction of anesthesia were the same (Online Resources 1A–D, 2A). By closer observation, however, we noticed that the tip of the RCC opened almost fully (Online Resource 1B). Because it was difficult to identify the morphological structure causing AS because of the rapid movement of the valve structures, we froze the moving image and reviewed it carefully by frame-by-frame advance. By means of this procedure, we could identify a DSM just below the RCC that obstructed the LVOT (Online Resources 3A,B) and thus could establish the diagnosis of DSS. Resection of the DSM was performed on mild hypothermic cardiopulmonary bypass (CPB). After ending CPB, we confirmed that the DSM was successfully resected (Online Resource 4A), the LVOT obstruction was released (Online Resource 4B), and the grade of AR was reduced from moderate to mild (Online Resource 2B). Continuous-wave Doppler recordings showed that the peak flow rate in the aorta decreased from 4.0 m/s before CPB to 2.6 m/s after CPB (Online Resources 5A,B). Our experience indicates that although TEE is superior to TTE in evaluating morphological features of DSS [1], careful examination is required to identify this structure even when using TEE in some patients with DSS.

Destructive acute infective endocarditis and purulent pericarditis

Infective endocarditis shows varied clinical status. Some papers presented the cases with spread of infection to the pericardium [1, 2]. A 28-year-old female patient presented with high-grade fever and dyspnea for several weeks. She also suffered from diarrhea and was administered intravenous doripenem. However. her condition worsened and she was admitted to a local hospital. Vegetations were detected by two-dimensional transthoracic echocardiography (TTE) and she was diagnosed with infective pericarditis. Blood cultures grew methicillinresistant Staphylococcus aureus (MRSA). She was treated with vancomycin and gentamicin sulfate. Multiple cerebral infarctions occurred on the second hospital day. On the fourth hospital day, congestive heart failure became more serious and she required high-dose catecholamine intubation and assisted ventilation. She was transferred to our hospital for operation. On admission, she was very sick and in shock. Chest X-ray showed severe pulmonary congestion. Large and pendulated vegetations were detected in the posterior mitral leaflets (Fig. 1a, b). We detected the abscess and dissection of the posterior mitral annulus and left atrial wall (arrow) (Fig. 1a–d). Two-dimensional color Doppler demonstrated to-and-fro abnormal flow from the left ventricle toward the mitral periannular abscess (Fig. 1e, f). TTE also revealed a circumferential dense mobile pericardial effusion. We considered that to be the abscess of the posterior mitral annulus, which extended to the left atrial wall, causing dissection, and perforated into both the left ventricle and left atrium, creating the communication between them. The wall of the left atrium was dissected. We diagnosed destructive acute infective endocarditis, periannular abscess, and purulent pericarditis. She was in a potentially lethal condition, so an emergency surgery of the mitral valve and left atrial reconstruction was immediately performed. We had no time to perform transesophageal echocardiography. The operation was performed through a median sternotomy under a mild hypothermic cardiopulmonary bypass. Marked accumulation of purulent pericardial fluid and pus was found (Fig. 2). There was a large vegetation on the P2 scallop of the mitral valve. The left atrial wall near the P2 and P3 scallops was dissected. The dissected space showed an abscess. Mitral valve repair was performed. The P2 and P3 scallops were resected and reconstructed by using a glutaraldehydetreated autologous pericardium patch. The left atrium was reconstructed by horse pericardium. Annuloplasty was performed by using autologous pericardium. On postoperative day 45, we performed TTE. The patient’s left ventricular function was normal and mitral regurgitation was not detected. After 6 weeks of treatment with intravenous vancomycin administration, she was discharged on foot on postoperative day 49.

Comparison between normothermic and mild hypothermic cardiopulmonary bypass in myocardial revascularization of patients with left ventricular dysfunction

The aim of this study was to investigate whether normothermic bypass is superior to mild hypothermia in patients with poor left ventricular function. This was achieved by studying defibrillation rates, postoperative requirements of cardiac pacing or other morbidity issues and mortality in patients with left ventricular dysfunction operated upon for elective coronary revascularization. Data were collected retrospectively from 252 consecutive patients with left ventricular dysfunction (ejection fraction ≤35%) undergoing coronary revascularization between January 2005 and January 2011. Patients operated upon under mild hypothermia (32 ºC) were placed in Group 1 and under normothermia (≥35 ºC) were placed in Group 2. Comorbidities and postoperative complications were recorded. There were 128 patients in Group 1 and 124 patients in Group 2. Plasma concentrations of CK-MB and troponin T peaked at 6 hours postoperatively, with no significant difference between the groups. Despite longer aortic cross-clamp time and total bypass time in Group 2, significantly less defibrillation requirement rates after aortic declamping was observed. Hospital mortality occured in 16 patients; 8 patients in each group. Normothermia enables less requirement for defibrillation after aortic declamping and postoperative cardiac pacing in patients with left ventricular dysfunction, which may be interpreted as better myocardial protection under normothermic bypass. However, maintaining normothermia had no effect on postoperative stroke, postoperative atrial fibrillation, renal failure development and mortality.

Establishment of a Coculture Model for Studying Inflammation After Pediatric Cardiopulmonary Bypass: from Bench to Bedside

Cardiopulmonary bypass (CPB) has been known to induce an inflammatory response that is influenced by various factors. Hypothermia is supposed to reduce inflammation after CPB. We developed an in vitro coculture model for CPB and compared the effects of hypothermia on the inflammatory response in the coculture model with results from a clinical prospective randomized trial. The coculture model consisted of endothelial cells and monocytes. Cells were stimulated with tumor necrosis factor (TNF)-α and exposed to deep hypothermia (20°C) or normothermia (37°C). In the clinical trial, 20 patients undergoing CPB for ventricular septum defect receive either normothermic (37°C) or mild hypothermic (32°C) CPB. We observed a significant interleukin (IL)-6 and IL-8 release in the coculture model 2 and 24 h after the experimental start. In the clinical trial, cytokines were significantly increased directly after weaning from CPB and remained elevated until 24 h. IL-8 and IL-6 secretions were similar in the hypothermic and normothermic group of the coculture model and the patients after 24 h. These results demonstrate that the inflammatory reaction observed in our coculture model is comparable with the cytokine increase in the blood of children undergoing CPB. Our coculture model could be useful for studies on the mechanisms of CPB-induced inflammation.

Open reconstruction of thoracoabdominal aortic aneurysms.

Technical details of our strategy for reconstructing the thoracoabdominal aorta are presented. Between October 1999 and June 2012, 152 patients underwent surgery for thoracoabdominal aortic aneurysms (Crawford classification type I =21, type II =43, type III =73, type IV =15). Mean age was 64.6±13.9 years. Sixty-three (41.4%) patients had aortic dissection, including acute type B dissection in 2 (1.2%) and ruptured aneurysms in 17 (11.2%). Eight (5.3%) patients had mycotic aneurysms, and 3 (2.0%) had aortitis. Emergent or urgent surgery was performed in 25 (16.4%) patients. Preoperative computed tomography (CT) scan or magnetic resonance (MR) angiography detected the Adamkiewicz artery in 103 (67.8%) patients. Cerebrospinal fluid drainage (CSFD) was performed in 115 (75.7%) patients and intraoperative motor evoked potentials were recorded in 97 (63.8%). One hundred and seven (70.4%) patients had reconstruction of the intercostal arteries from T7 to L2, 35 of which were reconstructed with the aortic patch technique and 72 with branched grafts. The mean number of reconstructed intercostal arteries was 3.1±2.5 pairs. Mild hypothermic partial cardiopulmonary bypass at 32-34 °C was used in 105 (69.1%) patients, left heart bypass was used in 4 (2.6%), and deep hypothermic cardiopulmonary bypass below 20 °C was used in 42 (27.6%). Thirty-day mortality was 9 (5.9%), and hospital mortality was 20 (13.2%). Independent risk factors for hospital mortality were emergency surgery (OR 13.4, P=0.003) and aortic cross clamping over 2 hours (OR 5.7, P=0.04). Postoperative spinal cord ischemia occurred in 16 (10.5%, 8 patients with paraplegia and 8 with paraparesis). Risk factors for developing spinal cord ischemic complications were prior surgery involving either the descending thoracic or the abdominal aorta (OR 3.75, P=0.05), diabetes mellitus (OR 5.49, P=0.03), and post-bypass hypotension <80 mmHg (OR 1.06, P=0.03). Postoperative survival at 5 years was 83.6±4.5%; 5-year survival was 47.5±8.6% in patients with spinal cord ischemia and 88.9±10.4% in those without spinal cord ischemia.

Blood conservation strategies for emergency open cardiac surgery in a patient with anti-M.

Blood conservation strategies for emergency open cardiac surgery in a patient with anti-M.

Near-infrared spectroscopy as a possible device for continuous monitoring of arterial carbon dioxide tension during cardiac surgery

Insufflation of carbon dioxide (CO(2)) to the operative field has been used to prevent major organ injury attributed to air embolisms in cardiac surgery. However, it may be preferable to avoid hypercapnia induced by CO(2) insufflation, owing to its potentially harmful effect. To investigate the effectiveness of near-infrared spectroscopy (NIRS) as a possible method for continuous monitoring of arterial CO(2) tension during cardiac surgery, we evaluated the correlation between the change in arterial CO(2) tension and the change in regional cerebral oxygen saturation (rScO(2)) obtained from NIRS in as controlled a condition as possible. Thirty patients who underwent surgical correction for atrial or ventricular septal defects were enrolled in this study. Patients who had pulmonary hypertension or other intracardiac anomalies were excluded. Anesthetic and cardiopulmonary bypass (CPB) management were conducted according to our standard institutional practice. Data obtained from arterial blood gas analyses and corresponding regional cerebral oxygen saturation (rScO(2)) recorded from NIRS before and after the insufflations of CO(2) during CPB were used for analysis. The change in arterial CO(2) tension correlated with the change in rScO(2) in the left hemisphere (r = 0.681, p <0.001, y = -1.393 + 0.547x) and right hemisphere (r = 0.690, p <0.001, y = -1.999 + 0.486x). To control the effects of other variables, including hematocrit and temperature, these relationship were not reduced (left hemisphere: r=0.678, p<0.001; right hemisphere: r=0.634, p<0.001). Since the change in regional cerebral oxygen saturation was correlated with the change in arterial CO(2) tension during mild hypothermic CPB, NIRS might be a possible non-invasive method for monitoring of arterial CO(2) tension without incurring additional cost in this setting.

Myocardial Contractility and Relaxation After Deep Hypothermic Circulatory Arrest in a Neonatal Piglet Model

Cooling before circulatory arrest or ischemic arrest has been reported to influence myocardial performance in isolated neonatal hearts. The aim of the present study was to analyze indices of myocardial contractility and relaxation in an in vivo neonatal model after deep hypothermic circulatory arrest (DHCA). DHCA (18°C; DHCA group; n = 8) or mild hypothermic cardiopulmonary bypass ([MH-CPB] 32°C; MH-CPB group; n = 10) was applied in newborn piglets. After reperfusion (60 and 120 min), left ventricular dP/dt(max) increased in DHCA and MH-CPB, while-dP/dt(max) decreased slightly in DHCA and increased in MH-CPB. Nevertheless, the differences between the two groups did not reach statistical significance. In conclusion, left ventricular contractility remained stable after reperfusion following DHCA, to some degree at the expense of the diastolic function.

Isoflurane pre-treatment before cardiopulmonary bypass alleviates neutrophil accumulation in dog lungs

This study investigated the effect of isoflurane pretreatment on cardiopulmonary bypass (CPB)-related lung injury. Twelve dogs were randomly divided into two groups of six each. In one group, 1.0 minimum alveolar concentration (MAC) of isoflurane was dministered for 30 min before CPB, while the control group received no anaesthetic. Both groups then underwent 100 min of mild hypothermic CPB with 60-min aortic cross clamping. Haemodynamic parameters, respiratory mechanics and alveolar arterial oxygen difference (AaDO₂) were measured during the experiment. One hundred and fifty minutes after CPB, lung tissue samples from the non-dependent and dependent portions of the left and right lungs were harvested for polymorphonulear leukocyte (PMNs) counts. Following CPB, within the control group, pulmonary vascular resistance (PVR) was significantly increased at 60, 120 and 180 min after declamping, AaDO₂ deteriorated at 180 min post-declamping, and dynamic lung compliance (DLC) was reduced dramatically after declamping. Isoflurane pretreatment before CPB significantly reduced PVR compared to the controls. AaDO₂ was impaired at 180 min after declamping and DLC was decreased after declamping within the isoflurane group. No differences in AaDO₂ and DLC were found between the isoflurane and control groups. At 180 min after declamping, the PMN count in both the non-dependent and dependent regions of the isoflurane pre-treated lungs was significantly lower than that of the controls. Our results suggest that 30-min pre-treatment with 1.0 MAC isoflurane before CPB caused a reduction in PMN accumulation in the dog lungs, inhibition of increases in PVR, and it did not affect AaDO₂ in the early post-CPB stage.

Pulsatile Flow Improves Cerebral Blood Flow in Pediatric Cardiopulmonary Bypass

The objective of this study was to evaluate the effect of pulsatile flow on cerebral blood flow (CBF) in infants with the use of a mild hypothermic cardiopulmonary bypass (CPB). Thirty infants scheduled for open heart surgery were randomized to the pulsatile group (Group P, n = 15) and nonpulsatile group (Group NP, n = 15). In Group P, pulsatile perfusion was applied during the aortic cross-clamping period, whereas nonpulsatile perfusion was used in Group NP. The systolic peak velocity (Vs), the end of diastolic velocity (Vd), the mean velocity (Vm), and the pulsatility index (PI) and the resistance index (RI) of the middle cerebral artery were measured by a transcranial Doppler (TCD) ultrasound after anesthesia (T1; baseline), at the beginning of CPB (T2), 10 min after aortic cross-clamping (T3), 3 min after declamping (T4), at the cessation of CPB (T5), and at the end of the operation (T6). During T3 and T4, the Vs in Group P was significantly higher than in Group NP. However, there were no statistically significant differences between Vd and Vm. The PI and RI in Group P were also higher than those in Group NP (both P < 0.05). During T5, Vd and Vm were higher in Group P (P < 0.05), whereas there was no difference in Vs. Additionally, PI and RI in Group P were significantly lower than those in Group NP (P < 0.05). However, there was no difference during T6. Pulsatile perfusion may increase CBF and decrease cerebral vascular resistance in the early period after mild hypothermic CPB.

Totally Endoscopic Robotic Atrial Septal Defect Repair on the Beating Heart

Atrial septal defect (ASD) repairs have successfully been performed on the arrested heart with the da Vinci S Surgical System (Intuitive Surgical). This study assessed the feasibility, safety, and efficacy of the use of the da Vinci S Surgical System for on-pump ASD repairs on the beating heart without cross-clamping the aorta. This prospective study included 24 consecutive patients who underwent ASD repair surgery between June 2008 and June 2009. All of the procedures were completed with the da Vinci S robot via 3 port incisions in the right chest and a 1.5-cm working port. The operations were carried out on the beating heart with mild hypothermic cardiopulmonary bypass (CPB) without cross-clamping the aorta. Venting the heart from the working port provided adequate visualization of the operative field. All patients underwent complete repairs. Fourteen patients underwent ASD closure with a fresh autogenous pericardial patch, and 10 patients underwent direct ASD closure. Concomitant surgery was required in 4 patients. The mean (+/-SEM) CPB time was 65.6 +/- 17.7 minutes, and the mean operative time was 98.5 +/- 19.3 minutes. No patient required transfusion of red blood cells. The length of patient stay in the intensive care unit was 0.5 to 1.0 days. The length of hospital stay was 4 to 5 days. Follow-up transthoracic echocardiography evaluations showed no residual atrial septal leakage. There were no operative deaths, strokes, or other complications. All of the patients were discharged. We have shown that use of the da Vinci S Surgical System to perform on-pump ASD repairs on the beating heart without cross-clamping the aorta is feasible, safe, and effective.