Intraoperative Hemodynamic Predictors of Mortality, Stroke, and Myocardial Infarction After Coronary Artery Bypass Surgery

Association between Intraoperative Hypotension and Hypertension and 30-day Postoperative Mortality in Noncardiac Surgery

BACKGROUND

Although deviations in intraoperative blood pressure are assumed to be associated with postoperative mortality, critical blood pressure thresholds remain undefined. Therefore, the authors estimated the intraoperative thresholds of systolic blood pressure (SBP), mean blood pressure (MAP), and diastolic blood pressure (DBP) associated with increased risk-adjusted 30-day mortality.

METHODS

This retrospective cohort study combined intraoperative blood pressure data from six Veterans Affairs medical centers with 30-day outcomes to determine the risk-adjusted associations between intraoperative blood pressure and 30-day mortality. Deviations in blood pressure were assessed using three methods: (1) population thresholds (individual patient sum of area under threshold [AUT] or area over threshold 2 SDs from the mean of the population intraoperative blood pressure values), (2). absolute thresholds, and (3) percent change from baseline blood pressure.

RESULTS

Thirty-day mortality was associated with (1) population threshold: systolic AUT (odds ratio, 3.3; 95% CI, 2.2 to 4.8), mean AUT (2.8; 1.9 to 4.3), and diastolic AUT (2.4; 1.6 to 3.8). Approximate conversions of AUT into its separate components of pressure and time were SBP < 67 mmHg for more than 8.2 min, MAP < 49 mmHg for more than 3.9 min, DBP < 33 mmHg for more than 4.4 min. (2) Absolute threshold: SBP < 70 mmHg for more than or equal to 5 min (odds ratio, 2.9; 95% CI, 1.7 to 4.9), MAP < 49 mmHg for more than or equal to 5 min (2.4; 1.3 to 4.6), and DBP < 30 mmHg for more than or equal to 5 min (3.2; 1.8 to 5.5). (3) Percent change: MAP decreases to more than 50% from baseline for more than or equal to 5 min (2.7; 1.5 to 5.0). Intraoperative hypertension was not associated with 30-day mortality with any of these techniques.

CONCLUSION

Intraoperative hypotension, but not hypertension, is associated with increased 30-day operative mortality.

Postoperative Critical Care of the Adult Cardiac Surgical Patient. Part I: Routine Postoperative Care

OBJECTIVES

Cardiac surgery, including coronary artery bypass, cardiac valve, and aortic procedures, is among the most common surgical procedures performed in the United States. Successful outcomes after cardiac surgery depend on optimum postoperative critical care. The cardiac intensivist must have a comprehensive understanding of cardiopulmonary physiology and the sequelae of cardiopulmonary bypass. In this concise review, targeted at intensivists and surgeons, we discuss the routine management of the postoperative cardiac surgical patient.

DATA SOURCE AND SYNTHESIS

Narrative review of relevant English-language peer-reviewed medical literature.

CONCLUSIONS

Critical care of the cardiac surgical patient is a complex and dynamic endeavor. Adequate fluid resuscitation, appropriate inotropic support, attention to rewarming, and ventilator management are key components. Patient safety is enhanced by experienced personnel, a structured handover between the operating room and ICU teams, and appropriate transfusion strategies.

The influence of acute pulmonary hypertension on cardiac output measurements: calibrated pulse contour analysis, transpulmonary and pulmonary artery thermodilution against a modified Fick method in an animal model

BACKGROUND

In critically ill patients with significant pulmonary hypertension (PH), close perioperative cardiovascular monitoring is mandatory, considering the increased morbidity and mortality in this patient group. Although the pulmonary artery catheter is still the standard for the diagnosis of PH, its use to monitor cardiac output (CO) in patients with PH is decreasing as a result of increased morbidity and possible influence of tricuspid regurgitation on the measurements. However, continuous CO measurement methods have never been evaluated under PH regarding their agreement and trending ability. In this study, we evaluated the influence of acute PH and different CO states on transpulmonary thermodilution (TPTD) and calibrated pulse contour analysis (PiCCO; both assessed with PiCCO plus™), intermittent pulmonary artery thermodilution (PATD), and continuous thermodilution (CCO) compared with a modified Fick method (FICK) in an animal model.

METHODS

Nine healthy pigs were studied under anesthesia. PH of 25 and 40 mm Hg (by administration of the thromboxane analog U46619), CO decreases, and CO increases were induced to test the different CO measurement techniques over a broad range of hemodynamic situations. Before each step, a new baseline data set was collected. CO values were compared using Bland-Altman analysis; trending abilities were assessed via concordance and polar plot analysis. The influence of pulmonary pressure on CO measurements was analyzed using linear mixed models.

RESULTS

A mean bias of -0.26 L/min with prediction intervals of -0.88 to 1.4 L/min was measured between TPTD and FICK. Their concordance rate was 100% (94%-100% confidence interval), and the mean polar angle -3° with radial limits of agreement of ±28° indicated good trending abilities. PATD compared with FICK also showed good trending ability. Comparisons of PiCCO and CCO versus FICK revealed low agreement and poor trending results with concordance rates of 84% (71%-93%) and 88% (74%-95%), mean polar angles from -17° and -19°, and radial limits of agreement of ±45° and 40°. Pulmonary pressures influenced only the difference between FICK and PiCCO, as assessed by linear mixed models.

CONCLUSIONS

TPTD compared with FICK was able to track all changes induced during the study period, including those by PH. It yielded better agreement than PATD both compared with FICK. PiCCO and CCO were not mapping all changes correctly, and when used clinically in unstable patients, regular controls with intermittent techniques are required. Acute pharmacologically induced PH did influence the difference between FICK and PiCCO.

Predictors of intraoperative hypotension and bradycardia

BACKGROUND

Perioperative hypotension and bradycardia in the surgical patient are associated with adverse outcomes, including stroke. We developed and evaluated a new preoperative risk model in predicting intraoperative hypotension or bradycardia in patients undergoing elective noncardiac surgery.

METHODS

Prospective data were collected in 193 patients undergoing elective, noncardiac surgery. Intraoperative hypotension was defined as systolic blood pressure <90 mm Hg for >5 minutes or a 35% decrease in the mean arterial blood pressure. Intraoperative bradycardia was defined as a heart rate of <60 beats/min for >5 minutes. A logistic regression model was developed for predicting intraoperative hypotension or bradycardia with bootstrap validation. Model performance was assessed using area under the receiver operating curves and Hosmer-Lemeshow tests.

RESULTS

A total of 127 patients developed hypotension or bradycardia. The average age of participants was 67.6 ± 11.3 years, and 59.1% underwent major surgery. A final 5-item score was developed, including preoperative Heart rate (<60 beats/min), preoperative hypotension (<110/60 mm Hg), Elderly age (>65 years), preoperative renin-Angiotensin blockade (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta-blockers), Revised cardiac risk index (≥3 points), and Type of surgery (major surgery), entitled the "HEART" score. The HEART score was moderately predictive of intraoperative bradycardia or hypotension (odds ratio, 2.51; 95% confidence interval, 1.79-3.53; C-statistic, 0.75). Maximum points on the HEART score were associated with an increased likelihood ratio for intraoperative bradycardia or hypotension (likelihood ratio, +3.64).

CONCLUSIONS

The 5-point HEART score was predictive of intraoperative hypotension or bradycardia. These findings suggest a role for using the HEART score to better risk-stratify patients preoperatively and may help guide decisions on perioperative management of blood pressure and heart rate-lowering medications and anesthetic agents.

Does preoperative carotid stenosis screening reduce perioperative stroke in patients undergoing coronary artery bypass grafting?

A number of institutions routinely perform carotid artery ultrasound screening before coronary artery bypass grafting (CABG) to identify carotid artery disease requiring revascularization before or during CABG, with the expectation of reducing perioperative neurologic events. The assumptions are that carotid disease is causally related to perioperative stroke and that prophylactic carotid revascularization decreases the risk of post-CABG neurologic events. Although carotid artery stenosis is a known risk factor for perioperative stroke in patients undergoing CABG, it might be a surrogate marker for diffuse atherosclerotic disease rather than a direct etiologic factor. Moreover, the benefit of prophylactic carotid revascularization in patients with asymptomatic unilateral carotid disease is uncertain. Therefore, we have reviewed the literature for evidence that preoperative carotid artery screening, by identifying patients with significant carotid artery stenosis and altering their management, reduces perioperative neurologic events in those undergoing CABG.

Perioperative hypertensive emergencies

The concept of "perioperative hypertensive emergency" must be defined differently from that of ambulatory hypertensive emergency in view of its unique clinical considerations in an atypical setting. It should be noted that moderately high normal blood pressure (BP) values in the perioperative setting often trigger situations requiring immediate treatment in what would otherwise be a "BP-acceptable" non-surgical condition. Commonly recognized circumstances that may result in a perioperative hypertensive emergency include exacerbation of severe mitral insufficiency, hypertension resulting in acute decompensated heart failure, hypertension caused by acute catecholamine excess, rebound hypertension after withdrawal of antihypertensive medications, hypertension resulting in bleeding from vascular surgery suture lines, intracerebral hemorrhage, aortic dissection, hypertension associated with preeclampsia, and hypertension associated with autonomic dysreflexia. In addition, perioperative BP lability has been reported to increase the risk for stroke, acute kidney injury, and 30-day mortality in patients undergoing cardiac surgery.

Impact of intraoperative vasopressor use in free tissue transfer for head, neck, and extremity reconstruction

General anesthesia induces hypotension and this is commonly treated intraoperatively with administering vasopressors. Microsurgeons are hesitant to use vasopressors due to the potential risk of inducing vasoconstriction and flap necrosis. The aim of this study was to determine the frequency of intraoperative vasopressor utilization in patients undergoing free tissue transfer reconstruction and to determine its impact on patient outcomes. An IRB-approved retrospective review was performed for 47 consecutive patients undergoing free tissue transfer for head, neck, and extremity reconstruction at Wake Forest Baptist Health over a 3-year period. Free flap survival was 97%, with 3% of patients having total flap necrosis and 17% with partial flap necrosis. The frequency of intraoperative vasopressor use was 53.2%. There was no significant difference in the frequency of total or partial flap necrosis between patients who received intraoperative vasopressors and those who did not. Similarly, there was no statistical significance in the rate of arterial or venous thrombosis between the 2 groups (P = 0.095 and P = 0.095, respectively). The use of vasopressors did not significantly increase postoperative complications. The timing of vasopressor administration did not affect outcomes. Intraoperative vasopressors are used more frequently than previously realized during free tissue transfer for reconstructive surgery. The use of intraoperative vasopressors does not appear to adversely affect outcomes of free tissue transfer. Further investigation and larger study size are needed to analyze the timing of drug administration, dose, and type of vasopressor to better understand the impact of intraoperative vasopressor use in free tissue transfer outcomes.

[Epidemiology of cerebral perioperative vascular accidents]

OBJECTIVES

Stroke is a well-described postoperative complication, after carotid and cardiac surgery. On the contrary, few studies are available concerning postoperative stroke in general non-cardiac non-carotid surgery. The high morbid-mortality of stroke justifies an extended analysis of recent literature.

ARTICLE TYPE

Systematic review.

DATA SOURCES

Firstly, Medline and Ovid databases using combination of stroke, cardiac surgery, carotid surgery, general non-cardiac non-carotid surgery as keywords; secondly, national and European epidemiologic databases; thirdly, expert and French health agency recommendations; lastly, reference book chapters.

RESULTS

In cardiac surgery, with an incidence varying from 1.2 to 10% according to procedure complexity, stroke occurs peroperatively in 50% of cases and during the first 48 postoperative hours for the others. The incidence of stroke after carotid surgery is 1 to 20% according to the technique used as well as operator skills. Postoperative stroke is a rare (0.15% as mean, extremes around 0.02 to 1%) complication in general surgery, it occurs generally after the 24-48th postoperative hours, exceptional peroperatively, and 40% of them occurring in the first postoperative week. It concerned mainly aged patient in high-risk surgeries (hip fracture, vascular surgery). Postoperative stroke was associated to an increase in perioperative mortality in comparison to non-postoperative stroke operated patients.

CONCLUSION

Postoperative stroke is a quality marker of the surgical teams' skill and has specific onset time and induces an increase of postoperative mortality.

Pharmacologic management of perioperative pulmonary hypertension

Perioperative pulmonary hypertension can originate from an established disease or acutely develop within the surgical setting. Patients with increased pulmonary vascular resistance are consequently at greater risk for complications. Despite the various specific therapies available, the ideal therapeutic approach in this patient population is not currently clear. This article describes the basic principles of perioperative pulmonary hypertension and reviews the different classes of agents used to promote pulmonary vasodilation in the surgical setting.

Current clinical management of pulmonary arterial hypertension

During the past 2 decades, there has been a tremendous evolution in the evaluation and care of patients with pulmonary arterial hypertension (PAH). The introduction of targeted PAH therapy consisting of prostacyclin and its analogs, endothelin antagonists, phosphodiesterase-5 inhibitors, and now a soluble guanylate cyclase activator have increased therapeutic options and potentially reduced morbidity and mortality; yet, none of the current therapies have been curative. Current clinical management of PAH has become more complex given the focus on early diagnosis, an increased number of available therapeutics within each mechanistic class, and the emergence of clinically challenging scenarios such as perioperative care. Efforts to standardize the clinical care of patients with PAH have led to the formation of multidisciplinary PAH tertiary care programs that strive to offer medical care based on peer-reviewed evidence-based, and expert consensus guidelines. Furthermore, these tertiary PAH centers often support clinical and basic science research programs to gain novel insights into the pathogenesis of PAH with the goal to improve the clinical management of this devastating disease. In this article, we discuss the clinical approach and management of PAH from the perspective of a single US-based academic institution. We provide an overview of currently available clinical guidelines and offer some insight into how we approach current controversies in clinical management of certain patient subsets. We conclude with an overview of our program structure and a perspective on research and the role of a tertiary PAH center in contributing new knowledge to the field.

A nomogram to predict major complications after hip and knee arthroplasty

We aimed to develop a nomogram for risk stratification of major postoperative complications in hip and knee arthroplasty based on preoperative and intraoperative variables, and assessed whether this tool would have better predictive performance compared to the Surgical Apgar Score (SAS). Logistic regression analysis was performed to develop a nomogram. Discrimination and calibration were assessed. Net reclassification improvement (NRI) was used to compare to the SAS. All variables were found to be statistically significant predictors of post-operative complications except race and lowest heart rate. The concordance index was 0.76 with good calibration. Compared to the SAS, the NRI was 71.5% overall. We developed a clinical prediction tool, the Morbidity and Mortality Acute Predictor for arthroplasty (arthro-MAP) that might be useful for postoperative risk stratification.

Perioperative management of the patient with pulmonary hypertension

Patients with pulmonary hypertension are at increased risk for perioperative morbidity and mortality. Elective surgery is generally discouraged in this patient population; however, there are times when surgery is deemed necessary. Currently, there are no guidelines for the preoperative risk assessment or perioperative management of subjects with pulmonary hypertension. The majority of the literature evaluating perioperative risk factors and mortality rates is observational and includes subjects with multiple etiologies of pulmonary hypertension. Subjects with pulmonary arterial hypertension, also referred to as World Health Organization group I pulmonary hypertension, and particularly those receiving pulmonary arterial hypertension-specific therapy may be at increased risk. Perioperative management of these patients requires a solid understanding and careful consideration of the hemodynamic effects of anesthetic agents, positive pressure ventilation and volume shifts associated with surgery in order to prevent acute right ventricular failure. We reviewed the most recent data regarding perioperative morbidity and mortality for subjects with pulmonary hypertension in an effort to better guide preoperative risk assessment and perioperative management by a multidisciplinary team.

[Management of patients with pulmonary hypertension]

Due to the increased survival of patients with pulmonary hypertension, even non-cardiac anesthesiologists will see these patients more frequently for anesthesia. The hemodynamic goal in the perioperative period is to avoid an increase in pulmonary vascular resistance (PVR) and to reduce a possibly pre-existing elevated PVR. Acute increases of chronically elevated PVR may result from hypoxia, hypercapnia, acidosis, hypothermia, elevated sympathetic output and also release of endogenous or application of exogenous pulmonary vasoconstrictors. Early recognition and treatment of these changes might be life saving in these patients. Drug interventions to perioperatively reduce PVR include administration of pulmonary vasodilators, such as oxygen, prostacyclines (epoprostenol, iloprost), phosphodiesterase III (milrinone) and V (sildenafil) inhibitors, as well as nitrates and nitric oxide. Along with the concept of selective pulmonary vasodilation inhalative administration of pulmonary vasodilators has benefits compared to intravenous administration. New therapeutic strategies, such as inhalational iloprost, inhalational milrinone and intravenous sildenafil can be introduced without significant technical support even in smaller departments.

Impact of Ascites on the Perioperative Course of Patients With Advanced Ovarian Cancer Undergoing Extensive Cytoreduction: Results of a Study on 119 Patients

Objective

Cytoreductive surgery for epithelial ovarian cancer (EOC) is the cornerstone of multimodal therapy and considered as a high-risk surgery because of extensive multivisceral procedures. In most patients, ascites is present, but its impact on the surgical and clinical outcomes is unclear.

Methods

One hundred nineteen patients undergoing surgical cytoreduction because of EOC between 2005 and 2008 were included. All surgical data and the individual tumor pattern were collected systematically based on a validated documentation tool (intraoperative mapping of ovarian cancer) during primary surgery. The amount of ascites was determined at the time of surgery, and 3 groups were classified (no ascites [NOA, n = 56], low amount of ascites [< 500 mL, n = 42], and high amount of ascites [HAS > 500 mL, n = 21]).

Results

Group NOA compared with HAS showed less transfusions of packed red blood cells (median [quartiles], 0 [0–2] vs 0 [0–2] vs 3 [1–4] U; P < 0.001) and fresh frozen plasma (median [quartiles], 0 [0–2] vs 0 [0–4] vs 2 [2–6] U; P < 0.001). In addition, in patients with ascites, noradrenaline was administered more frequently and in higher doses. The postoperative length of stay in the intensive care unit was significantly shorter in the NOA versus the group with low amount of ascites and HAS (median [quartiles], 1 [0–1] vs 1 [0–2] vs 2 [1–5] days; P < 0.001). The hospital length of stay is extended in HAS compared with that in NOA (median [quartiles], 16 [13–20] vs 17 [14–22] vs 21 [17–41] days; P = 0.004). Postoperative complications were increased in patients with ascites at the time of surgery (P = 0.007).

Conclusions

The presence of a high amount of ascites at cytoreductive surgery because of EOC is associated with higher amounts of blood transfusions, whereas the length of hospital stay and the postoperative intensive care unit treatment are significantly prolonged compared with those of patients without ascites.

Assessment of cardiac pathology by point-of-care ultrasonography performed by a novice examiner is comparable to the gold standard

Background

The aim of the study was to compare the diagnostic accuracy of point-of-care cardiac ultrasonography performed by a novice examiner against results from a specialist in cardiology with expert skills in echocardiography, with regard to the assessment of six clinically relevant cardiac conditions in a population of ward patients from the Department of Cardiology or the Department of Cardiothoracic Surgery.

Methods

Cardiac ultrasonography was performed by a novice examiner at the bedside and images were interpreted in a point-of-care context with dichotomous outcomes (yes/no). Six outcome categories were defined: 1) pericardial effusion (≥10 mm), 2) left ventricular dilatation (≥62 mm), 3) right ventricular dilatation (≥42 mm or ≥ left ventricular diameter), 4) left ventricular hypertrophy (≥13 mm), 5) left ventricular failure (EF ≤ 40%), 6) aortic stenosis (maximum flow velocity ≥3 m/s). The examiner was blinded to the patients’ medical history and results from previous echocardiographic examinations. Results from the interpreted point-of-care ultrasonography examination were compared with echocardiographic diagnosis made by a specialist in cardiology.

Results

A total of 102 medical and surgical patients were included. Assessments were made in six categories totalling 612 assessments. There was agreement between the novice examiner and the specialist in 95.6% of the cases; overall sensitivity was 0.91 and specificity was 0.97. Positive predictive value was 0.92 and negative predictive value was 0.97. Kappa statistics showed good agreement between observers (κ=0.88).

Conclusions

This study showed that a novice examiner was able to detect common and significant heart pathology in six different categories with good accuracy using POC ultrasonography.

Effect of preoperative pulmonary hypertension on outcomes in patients with severe aortic stenosis following surgical aortic valve replacement

Pulmonary hypertension (PH) is prevalent in patients with aortic stenosis (AS); however, previous studies have demonstrated inconsistent results regarding the association of PH with adverse outcomes after aortic valve replacement (AVR). The goal of this study was to evaluate the effects of preoperative PH on outcomes after AVR. We performed a regional prospective cohort study using the Northern New England Cardiovascular Disease Study Group database to identify 1,116 consecutive patients from 2005 to 2010 who underwent AVR ± coronary artery bypass grafting for severe AS with a preoperative assessment of pulmonary pressures by right-sided cardiac catheterization. PH was defined as a mean pulmonary artery pressure of ≥25 mm Hg, with severity based on the pulmonary artery systolic pressure-mild, 35 to 44 mm Hg; moderate, 45 to 59 mm Hg; and severe, ≥60 mm Hg. We found that PH was present in 536 patients (48%). Postoperative acute kidney injury, low-output heart failure, and in-hospital mortality increased with worsening severity of PH. In multivariate logistic regression, severe PH was independently associated with postoperative acute kidney injury (adjusted odds ratio 4.1, 95% confidence interval [CI] 1.7 to 10, p = 0.002) and in-hospital mortality (adjusted odds ratio 6.9, 95% CI 2.5 to 19.1, p <0.001). There was a significant association between PH and decreased 5-year survival (adjusted log-rank p value = 0.006), with severe PH being associated with the poorest survival (adjusted hazard ratio 2.4, 95% CI 1.3 to 4.2, p = 0.003). In conclusion, severe PH in patients with severe AS is associated with increased rates of in-hospital adverse events and decreased 5-year survival after AVR.

Risk factors for intraoperative hypotension during thyroid surgery

BACKGROUND

Hypotension is a common adverse effect of IV anaesthetics, especially during the induction of anaesthesia. The aim of our study was to determine the incidence and risk factors for intraoperative hypotension (IOH) in thyroid surgery, as well as to determine whether and to what extent IOH affects the occurrence of postoperative hypotension.

MATERIAL AND METHODS

The study included 1252 euthyroid patients, ASA 2 and ASA 3 status (American Society of Anesthesiologists physical status classification), who had thyroid surgery between 2007 and 2011. IOH was defined as a decrease in systolic blood pressure of >20% of baseline values. We studied the influence of demographic characteristics (sex, age, body mass index-BMI), comorbidity, type and duration of surgery, and anaesthesia on the occurrence of IOH. Univariate and multivariate logistic regression were used to determine predictors of occurrence of IOH.

RESULTS

IOH was registered in 6.5% of patients. The most common operation was thyroidectomy. Patients with IOH were younger, had lower BMI, and significantly less often had hypertension as a coexisting disease. The multivariate regression model identified BMI and the absence of hypertension as a coexisting disease, and as independent predictors of occurrence of IOH. Significantly more patients with IOH had postoperative hypotension (9.9% vs. 2.4%, p=0.000).

CONCLUSIONS

IOH is common, even during operations of short duration and with minimal bleeding. It is necessary to pay special attention to these patients, given that many of these patients remained hypotensive during the postoperative period.

Development and feasibility study of an algorithm for intraoperative goaldirected haemodynamic management in noncardiac surgery

This study developed an evidence-based, goal-directed haemodynamic management algorithm to standardize intraoperative haemodynamic therapy. A systematic literature search identified three haemodynamic management goals: stroke volume optimization by fluid therapy; maintenance of a target mean arterial pressure by vasopressor therapy; maintenance of a target cardiac index≥2.5 l/min per m2 by inotropic therapy. The algorithm was adapted to international standards and consensus was reached through a modified Delphi method at international meetings. Implementation of the algorithm into routine intraoperative management in noncardiac surgery was shown to be feasible. Compared with conventional haemodynamic management, use of the algorithm significantly reduced length of hospital stay, requirement for ventilation and incidence of prolonged hospital stay, thereby resulting in reduced hospital costs.

Obesity & hypertension are determinants of poor hemodynamic control during total joint arthroplasty: a retrospective review

Background

Proper blood pressure control during surgical procedures such as total joint arthroplasty (TJA) is considered critical to good outcome. There is poor understanding of the pre-operative risk factors for poor intra-operative hemodynamic control. The purpose of this study is to identify risk factors for poor hemodynamic control during TJA.

Methods

We performed a retrospective cohort analysis of 118 patients receiving TJA in the Dominican Republic. We collected patient demographic and comorbidity data. We developed an a priori definition for poor hemodynamic control: 1) Mean arterial pressure (MAP) <65% of preoperative MAP or 2) MAP >135% of preoperative MAP. We performed bivariate and multivariate analyses to identify risk factors for poor hemodynamic control during TJA.

Results

Hypertension was relatively common in our study population (76 of 118 patients). Average preoperative mean arterial pressure was 109.0 (corresponding to an average SBP of 149 and DBP of 89). Forty-nine (41.5%) patients had intraoperative blood pressure readings consistent with poor hemodynamic control. Based on multi-variable analysis preoperative hypertension of any type (RR 2.9; 95% CI 1.3-6.3) and an increase in BMI (RR 1.2 per 5 unit increase; 95% CI 1.0-1.5) were significant risk factors for poor hemodynamic control.

Conclusions

Preoperative hypertension and being overweight/obese increase the likelihood of poor blood pressure control during TJA. Hypertensive and/or obese patients warrant further attention and medical optimization prior to TJA. More work is required to elucidate the relationship between these risk factors and overall outcome.

Duration of preceding hypertension is associated with prolonged length of ICU stay

BACKGROUND

A substantial proportion of patients suffer prolonged length of intensive care unit stay (PLOS) or prolonged mechanical ventilation (PMV) following coronary artery bypass grafting (CABG). Identifying factors associated with PLOS and PMV would aid in patient risk stratification. We sought to identify the factors associated with PLOS and PMV following CABG.

METHODS

Participants were patients undergoing first-time elective CABG. All were observed until discharge and clinical data were collected on a standardized proforma. PLOS and PMV were defined a priori as >2 days and >12 h respectively, based on centre norms.

RESULTS

Of the 439 patients in the study, 105 (23.9%) had PLOS and 111 (25.2%) had PMV. Independent predictors of PMV were age, diabetes, previous myocardial infarction (MI), New York Heart Association (NYHA) class and statin use. The only independent predictor of PLOS was the duration of preceding hypertension.

CONCLUSION

The factors associated with PMV and PLOS in our study are easily attainable, routine clinical details and may be built into bed management algorithms. Confirmation of the association of preceding hypertension and subsequent investigation of the possible mechanism mediating this association, is suggested.

Clinical and biomarker profile of trauma-induced secondary cardiac injury

BACKGROUND

Secondary cardiac injury has been demonstrated in critical illness and is associated with worse outcomes. The aim of this study was to establish the existence of trauma-induced secondary cardiac injury, and investigate its impact on outcomes in injured patients.

METHODS

Injured adult patients eligible for enrolment in the Activation of Coagulation and Inflammation in Trauma 2 study, and admitted to the intensive care unit between January 2008 and January 2010, were selected retrospectively for the study. Markers of cardiac injury (brain natriuretic peptide (BNP), heart-type fatty acid binding protein (H-FABP) and troponin I) were measured on admission, and after 24 and 72 h in blood samples from injured patients. Individual records were reviewed for adverse cardiac events and death.

RESULTS

During the study period, 135 patients were enrolled (106 male, 78·5 per cent) with a median age of 40 (range 16-89) years. Eighteen patients (13·3 per cent) had an adverse cardiac event during admission and these events were not associated with direct thoracic injury. The in-hospital mortality rate was higher among the adverse cardiac event cohort: 44 per cent (8 of 18) versus 17·1 per cent (20 of 117) (P = 0·008). Raised levels of H-FABP and BNP at 0, 24 and 72 h, and troponin I at 24 and 72 h, were associated with increased adverse cardiac events. BNP levels were higher in non-survivors on admission (median 550 versus 403 fmol/ml; P = 0·022), after 24 h (794 versus 567 fmol/ml; P = 0·033) and after 72 h (1043 versus 753 fmol/ml; P = 0·036), as were admission troponin I levels.

CONCLUSION

Clinical and cardiac biomarker characteristics support the existence of trauma-induced secondary cardiac injury, which is associated with death, and unrelated to direct thoracic injury.

Documented Intraoperative Hypotension According to the Three Most Common Definitions Does Not Match the Application of Antihypotensive Medication

This observational study investigated which of the three most common definitions of intraoperative hypotension (IOH), reported in a published systematic literature review, were associated best with anaesthetists' administration of antihypo-tensive medication (AHM). IOH and AHM use in anaesthetic procedures in a mixed surgical population ( n = 2350) were also reviewed. The definitions were: arterial systolic blood pressure (SBP) < 100 mmHg or a fall in SBP of > 30% of the preoperative SBP baseline; arterial SBP < 80 mmHg; a fall in SBP of > 20% of the preoperative SBP. Accuracy of predicting AHM using these three definitions was 67%, 54% and 65%, respectively. Prediction by a new fourth definition, using an optimal threshold of minimal SBP falling to < 92 mmHg or by > 24% of preoperative baseline, was 68% accurate. In multivariate logistic analysis, age, volatile versus intravenous anaesthetics, medical history of arterial hypertension and all four definitions of IOH were associated with intraoperative AHM, however IOH was not associated with postoperative in-patient stay. The three original definitions correlated poorly with the anaesthetist's judgement about applying AHM. Anaesthetists make complex decisions regarding the relevance of IOH, considering various perioperative factors in addition to SBP. Age, physical status and duration and type of surgery showed better correlations with postoperative in-patient stay than IOH.

Pulmonary hypertension: an important predictor of outcomes in patients undergoing non-cardiac surgery

OBJECTIVES

Perioperative risk associated with pulmonary hypertension (PH) in patients undergoing non-cardiac surgery (NCS) remains poorly defined. We report perioperative outcomes in a large cohort of patients undergoing NCS, comparing those with and without PH.

METHODS

Patients undergoing NCS at our institution between January 2002 and December 2006, were cross matched with a Right Heart Catheterization (RHC) database for the same period. Patients were excluded if they were <18 years old and if they underwent cardiac surgery prior to NCS or minor procedures using local anesthesia or sedation. Controls were defined as patients who underwent similar NCS with mean pulmonary arterial pressure (MPAP) ≤ 25 mmHg.

RESULTS

173 patients underwent RHC and NCS during the specified period and were included in the analysis. Of these 96 (55%) had PH. Mean pulmonary arterial pressure (p = 0.001), American Association of Anesthesiology Class (p = 0.02), and chronic renal insufficiency (p = 0.03) were determined as independent risk factors for post-operative morbidity. Patients with PH were more likely to develop congestive heart failure (p < 0.001; OR: 11.9), hemodynamic instability (p < 0.002), sepsis (p < 0.0005), and respiratory failure (p < 0.004). Patients with PH needed longer ventilatory support (p < 0.002), stayed longer in the ICU (p < 0.04), and were more frequently readmitted to the hospital within 30 days (p < 008; OR 2.4).

CONCLUSIONS

In addition to the traditionally known risk factors for outcomes after NCS such as coronary artery disease, diabetes mellitus, chronic renal insufficiency, American Society of Anesthesiology class, the presence of underlying PH can have a significant negative impact on perioperative outcomes.

New pocket echocardiography device is interchangeable with high-end portable system when performed by experienced examiners

BACKGROUND

Cardiovascular status is a crucial determinant in the pre-operative assessment of patients for surgery as well as for the handling of patients with acute illness. We hypothesized that focus-assessed transthoracic echocardiography (FATE) could be performed with the subject in the semi-recumbent position. The aim was also to test whether the image quality of Vscan is interchangeable with a conventional high-quality portable echocardiography system. Furthermore, we evaluated the time needed to achieve an interpretable four-chamber view and to complete a full FATE examination.

METHODS

Sixty-one subjects were included. All subjects were examined in accordance with the FATE protocol in the semi-recumbent position on two different systems: the novel Vscan pocket device and the high-quality portable Vivid i system. Two evaluations were performed. In group A (n=30), the focus was on image quality. In group B (n=31), the focus was on the time consumed.

RESULTS

Group A: All patients (100%) had at least one image suitable for interpretation and no significant difference in image quality (P=0.32) was found between the two different systems. Group B: The mean value for the total time consumed for a full FATE was 69.3 s (59.8-78.8) on the Vscan and 63.7s (56.7-70.8) on the Vivid i, with no significant difference among the scanners (P=0.08).

CONCLUSION

The Vscan displays image quality interchangeable with larger and more expensive systems. The apparatus is well suited for performing a FATE examination in a 1-day surgery setting and could very well also be applicable in almost any situation involving patients with acute illness.

Risk of intraoperative hypotension with loop diuretics: a randomized controlled trial

BACKGROUND

There is growing concern regarding the safety of blood pressure-lowering medications administered during the perioperative period. Whether loop diuretics also induce intraoperative hypotension is uncertain. Our objective was to compare the effects of continuing or withholding furosemide on the day of noncardiac elective surgery on intraoperative hypotension among chronic users of furosemide.

METHODS

A double blind, randomized, placebo controlled trial was conducted at 3 North American university centers between September 2000 and December 2006. Participants were randomly assigned in a 1:1 ratio to receive either furosemide or placebo on the day of surgery. The primary outcome was risk of developing intraoperative hypotension. A priori secondary outcomes included risk of heart failure; composite cardiovascular event (myocardial infarction, arrhythmia, stroke or transient ischemic attack, or death); and change in renal function and electrolytes.

RESULTS

Of the 212 patients enrolled, 193 patients underwent surgery. There was no significant difference in risk of developing intraoperative hypotension between the furosemide (49%) and placebo (51.9%) groups (relative risk [RR], 0.95; 95% confidence interval [CI], 0.72-1.24; P = .78). The intraoperative administration of vasopressors and fluids were similar between both groups. The risk of developing postoperative cardiovascular events was not significantly different between those randomized to furosemide (4.8%) or placebo (2.8%) (RR, 1.73; 95% CI, 0.42-7.06; P = .49). There was no significant difference in renal function or electrolytes between the 2 groups.

CONCLUSION

Among elective, noncardiac surgeries in patients chronically treated with furosemide, the administration of furosemide on the day of surgery did not significantly increase the risk for intraoperative hypotension.

Usefulness of postoperative heart rate as an independent predictor of mortality after coronary bypass grafting

Heart rate (HR) predicts mortality and cardiovascular events in the general population and in patients with coronary artery disease. However, little evidence is available for patients after coronary revascularization. The aim of this study was to assess the prognostic value of ambulatory postoperative HR after coronary artery bypass grafting. Data from a prospective cohort study enrolling patients who underwent nonurgent coronary artery bypass grafting from 1998 to 2002 were analyzed. Baseline postoperative HR was measured 2 months after surgery, and patients were followed annually thereafter. The primary outcome was all-cause mortality. The secondary outcome combined any of the following events: death, nonfatal acute coronary syndromes, stroke or transient ischemic attack, secondary coronary revascularization, or vascular surgery. Seven hundred ninety-four patients (mean age 65.8 ± 9.3 years) were eligible for follow-up, predominantly men (84.1%). The mean follow-up duration was 3.2 ± 1.3 years, during which 40 patients (5.0%) died. In the univariate analysis, HR >90 beats/min was significantly associated with all outcomes. After adjustments for major confounding factors and the use of β blockers, postoperative HR >90 beats/min remained significantly associated with the secondary outcome (hazard ratio 2.26, 95% confidence interval 1.04 to 4.91, p = 0.04). Association of postoperative HR >90 beats/min with all-cause mortality was only borderline in the multivariate analysis (hazard ratio 3.57, 95% confidence interval 0.90 to 14.17, p = 0.07), because of the limited sample population size. In conclusion, postoperative HR >90 beats/min may be associated with poor prognoses in patients with coronary artery disease, even after surgical revascularization.

Application of an artificial neural network to predict postinduction hypotension during general anesthesia

BACKGROUND

Perioperative hypotension is associated with adverse outcomes in patients undergoing surgery. A computer-based model that integrates related factors and predicts the risk of hypotension would be helpful in clinical anesthesia. The purpose of this study was to develop artificial neural network (ANN) models to identify patients at high risk for postinduction hypotension during general anesthesia.

METHODS

Anesthesia records for March through November 2007 were reviewed, and 1017 records were analyzed. Eleven patient-related, 2 surgical, and 5 anesthetic variables were used to develop the ANN and logistic regression (LR) models. The quality of the models was evaluated by an external validation data set. Three clinicians were asked to make predictions of the same validation data set on a case-by-case basis.

RESULTS

The ANN model had an accuracy of 82.3%, sensitivity of 76.4%, and specificity of 85.6%. The accuracy of the LR model was 76.5%, the sensitivity was 74.5%, and specificity was 77.7%. The area under the receiver operating characteristic curve for the ANN and LR models was 0.893 and 0.840. The clinicians had the lowest predictive accuracy and sensitivity compared with the ANN and LR models.

CONCLUSIONS

The ANN model developed in this study had good discrimination and calibration and would provide decision support to clinicians and increase vigilance for patients at high risk of postinduction hypotension during general anesthesia.

Intraoperative Hemodynamic Instability During and After Separation From Cardiopulmonary Bypass

Every year, more than 1 million patients worldwide undergo cardiac surgery. Because of the aging of the population, cardiac surgery will increasingly be offered to patients at a higher risk of complications. The consequence is a reduced physiological reserve and hence an increased risk of mortality. These issues will have a significant impact on future health care costs because the population undergoing cardiac surgery will be older and more likely to develop postoperative complications. One of the most dreaded complications in cardiac surgery is difficult separation from cardiopulmonary bypass (CPB). When separation from CPB is associated with right-ventricular failure, the mortality rate will range from 44% to 86%. Therefore, the diagnosis and the preoperative prediction of difficult separation from CPB will be crucial to improve the selection and care of patients and to prevent complications for this high-risk patient population.

The intraoperative Surgical Apgar Score predicts postdischarge complications after colon and rectal resection

BACKGROUND

We previously developed an intraoperative 10-point Surgical Apgar Score-based on blood loss, lowest heart rate, and lowest mean arterial pressure-to predict major complications after colorectal resection. However, because complications often arise after uncomplicated hospitalizations, we sought to evaluate whether this intraoperative metric would predict postdischarge complications after colectomy.

METHODS

We linked our institution's National Surgical Quality Improvement Program database with an Anesthesia Intraoperative Management System for all colorectal resections over 4 years. Using Chi-square trend tests and logistic regression, we evaluated the Surgical Apgar Score's prediction for major postoperative complications before and after discharge.

RESULTS

Among 795 colectomies, there were 230 (29%) major complications within 30 days; 45 (20%) after uncomplicated discharges. Surgical Apgar Scores predicted both inpatient complications and late postdischarge complications (both P < .0001). Late complications occurred from 0 to 27 (median, 11) days after discharge; the most common were surgical site infections (42%), sepsis (24%), and venous thromboembolism (16%). In pairwise comparisons against average-scoring patients (Surgical Apgar Scores, 7-8), the relative risk of postdischarge complications trended lower, to 0.6 (95% confidence interval [CI], 0.2-1.7) for those with the best scores (9-10); and were significantly higher, at 2.6 (95% CI, 1.4-4.9) for scores 5-6, and 4.5 (95% CI, 1.8-11.0) for scores 0-4.

CONCLUSION

The intraoperative Surgical Apgar Score remained a useful metric for predicting postcolectomy complications arising after uncomplicated discharges. Even late complications may thus be related to intraoperative condition and events. Surgeons could use this intraoperative metric to target low-scoring patients for intensive postdischarge surveillance and mitigation of postdischarge complications after colectomy.

Perioperative complications in children with pulmonary hypertension undergoing general anesthesia with ketamine

BACKGROUND

Pulmonary arterial hypertension (PAH) is associated with significant perioperative risk for major complications in children, including pulmonary hypertensive crisis and cardiac arrest. Uncertainty remains about the safety of ketamine anesthesia in this patient population.

AIM

Retrospectively review the medical records of children with PAH to ascertain the nature and frequency of peri-procedural complications and to determine whether ketamine administration was associated with peri-procedural complications.

METHODS

Children with PAH (mean pulmonary artery pressure > or =25 mmHg and pulmonary vascular resistance index > or =3 Wood units) who underwent general anesthesia for procedures during a 6-year period (2002-2008) were enrolled. Details about the patient, PAH, procedure, anesthetic and postprocedural course were noted, including adverse events during or within 48 h of the procedure. Complication rates were reported per procedure. Association between ketamine and peri-procedural complications was tested.

RESULTS

Sixty-eight children (median age 7.3 year, median weight 22 kg) underwent 192 procedures. Severity of PAH was mild (23%), moderate (37%), and severe (40%). Procedures undertaken were major surgery (n = 20), minor surgery (n = 27), cardiac catheterization (n = 128) and nonsurgical procedures (n = 17). Ketamine was administered during 149 procedures. Twenty minor and nine major complications were noted. Incidence of cardiac arrest was 0.78% for cardiac catheterization procedures, 10% for major surgical procedures and 1.6% for all procedures. There was no procedure-related mortality. Ketamine administration was not associated with increased complications.

CONCLUSIONS

Ketamine appears to be a safe anesthetic option for children with PAH. We report rates for cardiopulmonary resuscitation and mortality that are more favorable than those previously reported.

Early on-cardiopulmonary bypass hypotension and other factors associated with vasoplegic syndrome

BACKGROUND

Vasoplegic syndrome is a form of vasodilatory shock that can occur after cardiopulmonary bypass (CPB). We hypothesized that the severity and duration of the decline in mean arterial pressure immediately after CPB is begun can be used as a predictor of patients will develop vasoplegia in the immediate post-CPB period and of poor clinical outcome. We quantified the decline in mean arterial pressure by calculating an area above the mean arterial blood pressure curve.

METHODS AND RESULTS

We retrospectively analyzed 2823 adult cardiac surgery cases performed between July 2002 and December 2006. Of these 2823, 577 (20.4%) were vasoplegic after separation from CPB. We found that 1645 patients (58.3%) had a clinically significant decline in mean arterial pressure after starting CPB (area above the mean arterial blood pressure curve >0) and were significantly more likely to become vasoplegic (23.0% versus 16.9%; odds ratio, 1.26; 95% confidence interval, 1.12 to 1.43; P<0.001). These patients were also far more likely either to die in hospital or to have a length of stay >10 days (odds ratio, 3.30; 95% confidence interval, 1.44 to 7.57; P=0.005). Additional risk factors for developing vasoplegia that were identified included the additive euroSCORE, procedure type, prebypass mean arterial pressure, length of bypass, administration of pre-CPB vasopressors, core temperature on CPB, pre- and post-CPB hematocrit, the preoperative use of beta-blockers or angiotensin-converting enzyme inhibitors, and the intraoperative use of aprotinin.

CONCLUSIONS

The results of this investigation suggest that it is possible to predict vasoplegia intraoperatively before separation from CPB and that the presence of a clinically significant area above the mean arterial blood pressure curve serves as a predictor of poor clinical outcome.

The effect of angiotensin-converting enzyme inhibitor on hemodynamic instability in patients undergoing cardiopulmonary bypass: results of a dose-comparison study

BACKGROUND

Recently, hemodynamic instability including hypotension and its effect on the clinical outcome in patients treated with angiotensin-converting enzyme inhibitors (ACEIs) during coronary artery bypass graft (CABG) has been described. However, no analysis has examined the dose of ACEIs and its risk of hypotension. In this study, we tested the hypothesis that a higher dose of ACEIs could lead to increased episodes of hypotension.

METHODS

A total of 300 patients scheduled for CABG were studied prospectively. They were divided into 3 groups according to their preoperative use of different doses of ACEIs. The demographic and medical characteristics were compared between these 3 groups. During CABG and throughout the intensive care unit (ICU), vasoconstrictors were infused in patients undergoing hypotension (mean arterial pressure [MAP] < 65 mm Hg or >30% below baseline). The predictive factors responsible for hypotension were investigated separately using univariate and multivariate logistic regression models.

RESULTS

The 3 groups were similar with regard to the patients' demographic and medical characteristics. The patients treated with ACEIs were more likely to develop hypotension (73% of high dose and 47% of low dose) in the operating room than those without ACEIs (30%). However, in the ICU, there was no significant association between hemodynamic changes and ACEIstreated patients. Other independent risk factors identified for hypotension were ejection fraction, history of myocardial infarction, coronary grafting count, and pump time during surgery and/or ICU admission.

CONCLUSIONS

Hemodynamic changes during CABG were observed to be directly proportional to the dosage of ACEIs prescribed preoperatively.

Anaesthesia and right ventricular failure

Acute right ventricular (RV) failure has until recently received relatively little attention in the cardiology, critical care or anaesthesia literature. However, it is frequently encountered in cardiac surgical cases and is a significant cause of mortality in patients with severe pulmonary hypertension who undergo non-cardiac surgery. RV dysfunction may be primarily due to impaired RV contractility, or volume or pressure overload. In these patients, an increased pulmonary vascular resistance (PVR) or a decreased aortic root pressure may lead to RV ischaemia, resulting in a rapid, downward haemodynamic spiral. The key aspects of 'RV protection' in patients who are at risk of perioperative decompensation are prevention, detection and treatment aimed at reversing the underlying pathophysiology. Minimising PVR and maintaining systemic blood pressure are of central importance in the prevention of RV decompensation, which is characterised by a rising central venous pressure and a falling cardiac output. Although there are no outcome data to support any therapeutic strategy for RV failure when PVR is elevated, the combination of inhaled iloprost or intravenous milrinone with oral sildenafil produces a synergistic reduction in PVR, while sparing systemic vascular resistance. Levosimendan is a promising new inotrope for the treatment of RV failure, although its role in comparison to older agents such as dobutamine, adrenaline and milrinone has yet to be determined. This is also the case for the use of vasopressin as an alternative pressor to noradrenaline. If all else has failed, mechanical support of the RV should be considered in selected cases.

Hemodynamic collapse under anesthesia in a patient with pulmonary artery sarcoma

PURPOSE

To describe a case of acute right ventricular dysfunction and hemodynamic collapse under general anesthesia in a patient undergoing resection of a pulmonary artery sarcoma.

CLINICAL FEATURES

A 67-yr-old woman with a presumptive diagnosis of pulmonary embolism presented to the hospital with progressive shortness of breath and syncope despite therapeutic anticoagulation. An echocardiogram revealed a large mass in the main pulmonary artery and a right ventricular systolic pressure of 105 mmHg. She was referred to our centre for urgent surgical management. One hour following induction of general anesthesia, the patient sustained sudden hemodynamic collapse. Transesophageal echocardiography revealed massive right ventricular dilation, effectively producing tamponade of the left ventricle. Urgent pericardiotomy was performed with immediate hemodynamic recovery. After initiation of cardiopulmonary bypass, the patient was found to have a large pulmonary artery sarcoma involving the pulmonary valve. Following successful resection with grafting and pulmonary valve replacement, the patient's trachea was extubated the following day, and she was discharged from hospital 1 week later in satisfactory condition.

CONCLUSIONS

Pulmonary artery sarcomas pose rare and unique challenges to the anesthesiologist. Given the high perioperative mortality, careful monitoring for catastrophic acute cor pulmonale is crucial. Urgent pericardiotomy or cardiopulmonary bypass for sudden hemodynamic collapse may be life-saving components of intraoperative management.