Sibu P. Saha

2012 Update to The Society of Thoracic Surgeons Guideline on Use of Antiplatelet Drugs in Patients Having Cardiac and Noncardiac Operations

Division of Cardiovascular and Thoracic Surgery, University of Kentucky, Lexington, Kentucky (VAF and SPS); Department of Pharmacy Practice, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (JHO); Division of Cardiothoracic Surgery, Oregon Health and Science University Medical Center, Portland, Oregon (HKS); State University of New York, Stony Brook School of Medicine, Stony Brook, New York (TR); Department of Cardiothoracic Surgery, University of Colorado Health Sciences Center, Aurora, Colorado (TBR); Department of Anesthesia, St. Michael’s Hospital, University of Toronto, Toronto, Ontario (CDM); Division of Cardiovascular Surgery, Sanger Clinic, Charlotte, North Carolina (CRB); Departments of Anesthesiology, Immunology, and Pathology, Washington University School of Medicine, St. Louis, Missouri (GJD); and The Society of Thoracic Surgeons, Chicago, Illinois (KJ and ERC)

Noninvasive optical evaluation of spontaneous low frequency oscillations in cerebral hemodynamics

Spontaneous low frequency oscillations (LFOs) around 0.1 Hz have been observed in mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV). Previous studies have shown that cerebral autoregulation in major arteries can be assessed by quantification of the phase shift between LFOs of MAP and CBFV. However, many cerebral diseases are associated with abnormal microvasculature and tissue dysfunction in brain, and quantification of these abnormalities requires direct measurement of cerebral tissue hemodynamics. This pilot study used a novel hybrid near-infrared diffuse optical instrument to noninvasively and simultaneously detect LFOs of cerebral blood flow (CBF) and cerebral oxygenation (i.e., oxygenated/deoxygenated/total hemoglobin concentration: [HbO(2)]/[Hb]/THC) in human prefrontal cortex. Using the hybrid instrument and a finger plethysmograph, the dynamic changes of CBF, [HbO(2)], [Hb], THC and MAP were concurrently measured in 15 healthy subjects at rest, during 70° head-up-tilting (HUT) and during enforced breathing at 0.1 Hz. The LFOs were extracted from the measured variables using power spectral analysis, and the phase shifts and coherences of LFOs between MAP and each of the measured hemodynamic variables were calculated from the corresponding transfer functions. Levels of coherence (>0.4) were used to judge the success of LFO measurements. We found that CBF, [HbO(2)] and THC were reliable hemodynamic parameters in detecting LFOs and HUT was the most robust and stable protocol for quantifying phase shifts of hemodynamic LFOs. Comparing with other relevant studies, similar success rates for detecting cerebral LFOs have been achieved in our study. The phase shifts of LFOs in CBF were also close to those in CBFV reported by other groups, although the results in cerebral oxygenation measurements during enforced breathing varied across studies. Future study will investigate cerebral LFOs in patients with cerebral impairment and evaluate their cerebral autoregulation capabilities and neurocognitive functions via the quantification of LFO phase shifts.

Cerebral monitoring during carotid endarterectomy using near-infrared diffuse optical spectroscopies and electroencephalogram

Intraoperative monitoring of cerebral hemodynamics during carotid endarterectomy (CEA) provides essential information for detecting cerebral hypoperfusion induced by temporary internal carotid artery (ICA) clamping and post-CEA hyperperfusion syndrome. This study tests the feasibility and sensitivity of a novel dual-wavelength near-infrared diffuse correlation spectroscopy technique in detecting cerebral blood flow (CBF) and cerebral oxygenation in patients undergoing CEA. Two fiber-optic probes were taped on both sides of the forehead for cerebral hemodynamic measurements, and the instantaneous decreases in CBF and electroencephalogram (EEG) alpha-band power during ICA clamping were compared to test the measurement sensitivities of the two techniques. The ICA clamps resulted in significant CBF decreases (-24.7 ± 7.3%) accompanied with cerebral deoxygenation at the surgical sides (n = 12). The post-CEA CBF were significantly higher (+43.2 ± 16.9%) than the pre-CEA CBF. The CBF responses to ICA clamping were significantly faster, larger and more sensitive than EEG responses. Simultaneous monitoring of CBF, cerebral oxygenation and EEG power provides a comprehensive evaluation of cerebral physiological status, thus showing potential for the adoption of acute interventions (e.g., shunting, medications) during CEA to reduce the risks of severe cerebral ischemia and cerebral hyperperfusion syndrome.

Intraoperative transfusion of small amounts of blood heralds worse postoperative outcome in patients having noncardiac thoracic operations.

BACKGROUND Massive intraoperative transfusion is associated with increased morbidity and mortality in patients undergoing noncardiac thoracic operations. We examined whether this association carries over to patients who receive only 1 to 2 units of packed red blood cells (PRBCs) during their operation. METHODS We queried the American College of Surgeons National Surgical Quality Improvement Project database for patients undergoing noncardiac, nonvascular thoracic operations during a 5-year period. Patient 30-day morbidity (1 or more of 20 complications) and mortality were evaluated. We used propensity-score matching to minimize confounding when estimating the effect of transfusion on postoperative morbidity. RESULTS We analyzed 8728 nonvascular thoracic operations in patients from 173 hospitals. Of these, 7875 (90.2%) did not receive intraoperative transfusions. The 579 patients (6.6%) who received 1 to 2 units of intraoperative PRBCs had higher unadjusted rates of wound problems, pulmonary complications, sepsis/shock, composite morbidity, mortality, and length of stay than those who did not receive transfusions. These rates further increased with postoperative transfusion of more than 2 units of intraoperative PRBC. After propensity adjustment, transfusion of 1 or 2 units of PRBCs increased the multivariate risk of composite morbidity, pulmonary complications, systemic sepsis, wound complications, and the postoperative length of stay compared with those who did not receive transfusions. CONCLUSIONS In patients undergoing noncardiac thoracic operations, there is a dose-dependent adverse effect of intraoperative blood transfusion on outcomes, with even seemingly small amounts of blood (1 or 2 units of PRBCs) increasing morbidity and resource utilization. Clinicians should be cautious with intraoperative transfusions of 1 or 2 units of PRBC for mildly hypovolemic or anemic patients.

Intraoperative evaluation of revascularization effect on ischemic muscle hemodynamics using near-infrared diffuse optical spectroscopies

Arterial revascularization in patients with peripheral arterial disease (PAD) reestablishes large arterial blood supply to the ischemic muscles in lower extremities via bypass grafts or percutaneous transluminal angioplasty (PTA). Currently no gold standard is available for assessment of revascularization effects in lower extremity muscles. This study tests a novel near-infrared diffuse correlation spectroscopy flow-oximeter for monitoring of blood flow and oxygenation changes in medial gastrocnemius (calf) muscles during arterial revascularization. Twelve limbs with PAD undergoing revascularization were measured using a sterilized fiber-optic probe taped on top of the calf muscle. The optical measurement demonstrated sensitivity to dynamic physiological events, such as arterial clamping/releasing during bypass graft and balloon inflation/deflation during PTA. Significant elevations in calf muscle blood flow were observed after revascularization in patients with bypass graft (+48.1 ± 17.5%) and patients with PTA (+43.2 ± 11.0%), whereas acute post-revascularization effects in muscle oxygenation were not evident. The decoupling of flow and oxygenation after revascularization emphasizes the need for simultaneous measurement of both parameters. The acute elevations/improvements in calf muscle blood flow were associated with significant improvements in symptoms and functions. In total, the investigation corroborates potential of the optical methods for objectively assessing the success of arterial revascularization.

Identification of patients with postoperative complications who are at risk for failure to rescue.

IMPORTANCE A minority of patients who experience postoperative complications die (failure to rescue). Understanding the preoperative factors that lead to failure to rescue helps surgeons predict and avoid operative mortality. OBJECTIVE To provide a mechanism for identifying a high-risk group of patients with postoperative complications who are at a substantially increased risk for failure to rescue. DESIGN, SETTING, AND PATIENTS Observational study evaluating failure to rescue in patients entered into the American College of Surgeons National Surgical Quality Improvement Program database. The large sample of surgical patients included in this study underwent a wide range of operations during a 5-year period in more than 200 acute care hospitals. We examined and identified patients at high risk for failure to rescue using propensity stratification. We also developed a risk-scoring system that allowed preoperative identification of patients at the highest risk for failure to rescue. MAIN OUTCOMES AND MEASURES Risk-scoring system that predicts failure to rescue. RESULTS Of the 1,956,002 database patients, there were 207,236 patients who developed serious postoperative complications. Deaths occurred in 21,731 patients with serious complications (10.5% failure to rescue). Stratification of patients into quintiles, according to their propensity for developing serious complications, found that 90% of operative deaths occurred in the highest-risk quintile, usually within a week of developing the initial complication. A risk-scoring system for failure to rescue, based on regression-derived variable odds ratios, predicted patients in the highest-risk quintile with good predictive accuracy. Only 31.8% of failure-to-rescue patients had a single postoperative complication. Perioperative deaths increased exponentially as the number of complications per patient increased. Patients with complications who had surgical residents involved in their care had reduced rates of failure to rescue compared with patients without resident involvement. CONCLUSIONS AND RELEVANCE Twenty percent of high-risk patients account for 90% of failure to rescue (Pareto principle). More than two-thirds of patients with failure to rescue have multiple complications. On average, a few days elapse before death following a complication. A risk-scoring system based on preoperative variables predicts patients in the highest-risk category of failure to rescue with good accuracy. In high-risk patients who develop complications, our results suggest that early intervention, preferably in a high-level intensive care facility with a surgical training program, offers the best chance to reduce failure-to-rescue rates.

A Randomized, Double-Blind Trial Comparing Continuous Thoracic Epidural Bupivacaine With and Without Opioid in Contrast to a Continuous Paravertebral Infusion of Bupivacaine for Post-thoracotomy Pain

OBJECTIVE To compare the results of continuous epidural bupivacaine analgesia with and without hydromorphone to continuous paravertebral analgesia with bupivcaine in patients with post-thoracotomy pain. DESIGN A prospective, randomized, double-blinded trial. SETTING A teaching hospital. PARTICIPANTS Patients at a tertiary care teaching hospital undergoing throracotomy for lung cancer. INTERVENTIONS Subjects were assigned randomly to receive a continuous thoracic epidural or paravertebral infusion. Patients in the epidural group were randomized to receive either bupivacaine alone or in combination with hydromorphone. Visual analog scores as well as incentive spirometery results were obtained before and after thoracotomy. METHODS AND MAIN RESULTS Seventy-five consecutive patients presenting for thoracotomy were enrolled in this institutional review board-approved study. On the morning of surgery, subjects were randomized to either an epidural group receiving bupvicaine with and without hydromorphone or a paravertebral catheter-infused bupvicaine. Postoperative visual analog scores and incentive spirometry data were measured in the postanesthesia care unit, the evening of the first operative day, and daily thereafter until postoperative day 4. Analgesia on all postoperative days was superior in the thoracic epidural group receiving bupivacaine plus hydromorphone. Analgesia was similar in the epidural and continuous paravertebral groups receiving bupivacaine alone. No significant improvement was noted by combining the continuous infusion of bupivacaine via the paravertebral and epidural routes. Incentive spirometry goals were best achieved in the epidural bupivacaine and hydromorphone group and equal in the group receiving bupivacaine alone either via epidural or continuous paravertebral infusion. CONCLUSIONS The current study provided data that fill gaps in the current literature in 3 important areas. First, this study found that thoracic epidural analgesia (TEA) with bupivacaine and a hydrophilic opioid, hydromorphone, may provide enhanced analgesia over TEA or continuous paravertebral infusion (CPI) with bupivacaine alone. Second, in the bupivacaine-alone group, the increased basal rates required to achieve analgesia resulted in hypotension more frequently than in the bupivacaine/hydromorphone combination group, underscoring the benefit of the synergistic activity. Finally, in agreement with previous retrospective studies, the current data suggest that CPI of local anesthetic appears to provide acceptable analgesia for post-thoracotomy pain.

Institutional variability of intraoperative red blood cell utilization in coronary artery bypass graft surgery.

The variability in frequency of allogeneic blood transfusion during coronary artery bypass surgery (CABG) is a concern. Evidence-based guidelines support minimizing the use of blood during open heart surgery. The Hospital Clinical Services Group quality indicator database was queried for intraoperative red blood cell (RBC) transfusions in 17 252 isolated CABG surgery cases during 2007. Institutional variability was observed in the frequency of intraoperative RBC transfusion rates, which ranged from 0% to 85.7%. The institution mean RBC transfusion rate was 40.8%. Regional geographic and cardiac program size variations were observed in RBC transfusion rates and volume with significant variation. Notable institutional variability persists with respect to intraoperative RBC transfusion in isolated CABG surgery despite clear evidence and guidelines to support techniques to minimize RBC transfusion. Such results support the hypothesis that incorporating evidence-based transfusion-related practices in open heart surgery are not uniformly adopted.

The relationship between mortality and preexisting cardiac disease in 5,971 trauma patients.

BACKGROUND We observed significant morbidity and mortality in patients with preexisting cardiac disease who suffer severe traumatic injuries. We wondered about the types of injury seen and about the cardiac risks factors that predispose to worse outcomes in these patients. Our hypothesis is that significant cardiac comorbidity is associated with adverse trauma outcomes. METHODS We reviewed 10,144 trauma admissions to the University of Kentucky during a 5-year period (2002-2007) in patients 21 years or older. The types and extent of injuries were characterized, and risk factors for poor outcome were assessed. Propensity analysis assessed variable interaction and adjusted for important multivariate cardiovascular risk factors. RESULTS Of the 10,144 adult trauma patients, there was adequate cardiovascular history before emergency treatment in 5,971 patients (58.9%). Of the 700 trauma deaths, 236 (33.7%) had adequate medical history to allow accurate assessment of cardiovascular disease. Significant multivariate predictors of trauma-related death included older age (odds ratio [OR] = 0.938), injury severity score (OR = 0.893 per unit score), major burn (OR = 5.907), assault with a weapon (OR = 3.205), systolic blood pressure divided by Glasgow coma score (OR = 0.958 per score unit), and female (OR = 1.629). In the cohort of 236 deaths with adequate medical history, severe head and chest injuries caused death in 187 patients (79.2%). Significant propensity-adjusted cardiovascular risks of trauma death included preinjury warfarin use (OR = 2.309, p = 0.001), congestive heart failure (CHF) (OR = 2.060, p = 0.011), and preinjury beta-blocker use (OR = 2.62, p = 0.001). The highest mortality rates occurred in patients with combinations of these cardiovascular risk factors. For example, patients on warfarin with CHF had a 26.3% mortality rate, whereas patients on warfarin and beta-blocker had a 27.3% mortality rate. CONCLUSIONS Preinjury cardiac risk factors, especially preinjury warfarin, beta-blocker use, and CHF, are independent multivariate predictors of mortality in patients suffering significant trauma. Although head and chest injuries are the most frequent causes of death, patients with more than one preinjury cardiac risk factor have 5 to 10 times the mortality risk compared with those without cardiac risks.

A prospective randomized study comparing fibrin sealant to manual compression for the treatment of anastomotic suture-hole bleeding in expanded polytetrafluoroethylene grafts

OBJECTIVE The ideal hemostatic agent for treatment of suture-line bleeding at vascular anastomoses has not yet been established. This study evaluated whether the use of a fibrin sealant containing 500 IU/mL thrombin and synthetic aprotinin (FS; marketed in the United States under the name TISSEEL) is beneficial for treatment of challenging suture-line bleeding at vascular anastomoses of expanded polytetrafluoroethylene (ePTFE) grafts, including those further complicated by concomitant antiplatelet therapies. METHODS Over a 1-year period ending in 2010, ePTFE graft prostheses, including arterio-arterial bypasses and arteriovenous shunts, were placed in 140 patients who experienced suture-line bleeding that required treatment after completion of anastomotic suturing. Across 24 US study sites, 70 patients were randomized and treated with FS and 70 with manual compression (control). The primary end point was the proportion of patients who achieved hemostasis at the study suture line at 4 minutes after start of application of FS or positioning of surgical gauze pads onto the study suture line. RESULTS There was a statistically significant difference in the comparison of hemostasis rates at the study suture line at 4 minutes between FS (62.9%) and control (31.4%) patients (P < .0001), which was the primary end point. Similarly, hemostasis rates in the subgroup of patients on antiplatelet therapies were 64.7% (FS group) and 28.2% (control group). When analyzed by bleeding severity, the hemostatic advantage of FS over control at 4 minutes was similar (27.8% absolute improvement for moderate bleeding vs 32.8% for severe bleeding). Logistic regression analysis (accounting for gender, age, intervention type, bleeding severity, blood pressure, heparin coating of ePTFE graft, and antiplatelet therapies) found a statistically significant treatment effect in the odds ratio (OR) of meeting the primary end point between treatment groups (OR, 6.73; P < .0001), as well as statistically significant effects for intervention type (OR, 0.25; P = .0055) and bleeding severity (OR, 2.59; P = .0209). The safety profile of FS was excellent as indicated by the lack of any related serious adverse events. CONCLUSIONS The findings from this phase 3 study confirmed that FS is safe and its efficacy is superior to manual compression for hemostasis in patients with peripheral vascular ePTFE grafts. The data also suggest that FS promotes hemostasis independently of the patients own coagulation system, as shown in a representative population of patients with vascular disease under single- or dual-antiplatelet therapies.