Stuart A. McCluskey

Acute Kidney Injury After Cardiac Surgery Focus on Modifiable Risk Factors

Background— Acute kidney injury (AKI) after cardiac surgery is a major health issue. Lacking effective therapies, risk factor modification may offer a means of preventing this complication. The objective of the present study was to identify and determine the prognostic importance of such risk factors. Methods and Results— Data from a multicenter cohort of 3500 adult patients who underwent cardiac surgery at 7 hospitals during 2004 were analyzed (using multivariable logistic regression modeling) to determine the independent relationships between 3 thresholds of AKI (>25%, >50%, and >75% decrease in estimated glomerular filtration rate within 1 week of surgery or need for postoperative dialysis) with death rates, as well as to identify modifiable risk factors for AKI. The 3 thresholds of AKI occurred in 24% (n=829), 7% (n=228), and 3% (n=119) of the cohort, respectively. All 3 thresholds were independently associated with a >4-fold increase in the odds of death and could be predicted with several perioperative variables, including preoperative intra-aortic balloon pump use, urgent surgery, and prolonged cardiopulmonary bypass. In particular, 3 potentially modifiable variables were also independently and strongly associated with AKI. These were preoperative anemia, perioperative red blood cell transfusions, and surgical reexploration. Conclusions— AKI after cardiac surgery is highly prevalent and prognostically important. Therapies aimed at mitigating preoperative anemia, perioperative red blood cell transfusions, and surgical reexploration may offer protection against this complication.

Early clinical experience with a new videolaryngoscope (GlideScope) in 728 patients.

PurposeTo evaluate a new videolaryngoscope and assess its ability to provide laryngeal exposure and facilitate intubation.MethodsFive centres, involving 133 operators and a total of 728 consecutive patients, participated in the evaluation of a new videolaryngoscope [GlideScope® (GS)]. Many operators had limited or no previous GS experience. We collected information about patient demographics and airway characteristics, Cormack-Lehane (C/L) views and the ease of intubation using the GS. Failure was defined as abandonment of the technique.ResultsData from six patients were incomplete and were excluded. Excellent (C/L 1) or good (C/L 2) laryngeal exposure was obtained in 92% and 7% of patients respectively. In all 133 patients in whom both GS and direct laryngoscopy (DL) were performed, GS resulted in a comparable or superior view. Among the 35 patients with C/L grade 3 or 4 views by DL, the view improved to a C/L 1 view in 24 and a C/L 2 view in three patients. Intubation with the GS was successful in 96.3% of patients. The majority of the failures occurred despite a good or excellent glottic view.ConclusionsGS laryngoscopy consistently yielded a comparable or superior glottic view compared with DL despite the limited or lack of prior experience with the device. Successful intubation was generally achieved even when DL was predicted to be moderately or considerably difficult. GS was abandoned in 3.7% of patients. This may reflect the lack of a formal protocol defining failure, limited prior experience or difficulty manipulating the endotracheal tube while viewing a monitor.RésuméObjectifÉvaluer un nouveau vidéolaryngoscope et tester sa capacité à fournir une exposition du larynx et à faciliter l’intubation.MéthodeCinq centres, impliquant 133 opérateurs et 728 patients consécutifs, ont participé à l’évaluation du nouveau vidéolaryngoscope [GlideScope® (GS)]. De nombreux opérateurs avaient une expérience nulle ou limitée du GS. Nous avons noté les données démographiques et les caractéristiques des voies aériennes, la classification Cormack-Lehane (C/L) des visualisations et la facilité à intuber avec le GS. Un échec était défini comme un abandon de la technique. Résultats: Six patients ont été exclus à cause de données incomplètes. Une excellente (C/L 1) ou une bonne (C/L 2) exposition du larynx a été obtenue chez 92 % et 7 % des patients respectivement. Chez les 133 patients soumis aux deux tests avec le GS et à la laryngoscopie directe (LD), le GS a donné des résultats comparables ou une vue supérieure. Parmi les 35 patients avec un grade 3 ou 4 de C/L par LD, la visualisation s’est améliorée à 1 C/L chez 24 patients et à 2 C/L chez trois patients. L’intubation avec le GS a été réussie chez 96,3 % des patients. La majorité des échecs sont survenus malgré une bonne ou une excellente visualisation glottique.ConclusionLa laryngoscopie avec le GS fournit toujours une vision glottique comparable ou supérieure à la LD malgré l’expérience nulle ou limitée avec l’appareil. L’intubation a été généralement réussie même lorsqu’on prévoyait une difficulté modérée ou importante de la LD. Le GS a été abandonné chez 3,7 % des patients. Cela pourrait correspondre au manque de protocole formel définissant l’échec, à l’expérience antérieure limitée ou à la difficulté de manipuler le tube endotrachéal tout en surveillant l’écran.

A propensity score case‐control comparison of aprotinin and tranexamic acid in high‐transfusion‐risk cardiac surgery

BACKGROUND:  Cardiac surgery with cardiopulmonary bypass may result in excessive fibrinolysis and platelet (PLT) dysfunction, resulting in impaired hemostasis and excessive blood loss. Prophylactic use of the antifibrinolytic drugs aprotinin and tranexamic acid is thought to prevent these hemostatic defects. Their relative clinical utility and safety in high‐transfusion‐risk cardiac surgery, however, is not known.

The independent association of massive blood loss with mortality in cardiac surgery

BACKGROUND:  Although the association between massive perioperative blood loss (MBL) and adverse outcomes is well recognized, it is unclear whether MBL is an independent risk factor or, instead, simply a marker for other adverse events or severity of illness. The objective of this cohort study was to quantify the independent association of MBL in cardiac surgery with all‐cause in‐hospital mortality.

Recombinant factor VIIa for intractable blood loss after cardiac surgery: a propensity score-matched case-control analysis.

BACKGROUND:  Cardiac surgery is occasionally complicated by massive blood loss that is refractory to standard hemostatic interventions. Recombinant factor VIIa (rF‐VIIa) is being increasingly used as rescue therapy in such cases, but little information is available on its safety and efficacy for this indication.

Hyperchloremia after noncardiac surgery is independently associated with increased morbidity and mortality: a propensity-matched cohort study.

BACKGROUND: The use of normal saline is associated with hyperchloremic metabolic acidosis. In this study, we sought to determine the incidence of acute postoperative hyperchloremia (serum chloride >110 mEq/L) and whether this electrolyte disturbance is associated with an increase in length of hospital stay, morbidity, or 30-day postoperative mortality. METHODS: Data were retrospectively collected on consecutive adult patients (>18 years of age) who underwent inpatient, noncardiac, nontransplant surgery between January 1, 2003 and December 31, 2008. The impact of postoperative hyperchloremia on patient morbidity and length of hospital stay was examined using propensity-matched and logistic multivariable analysis. RESULTS: The dataset consisted of 22,851 surgical patients with normal preoperative serum chloride concentration and renal function. Acute postoperative hyperchloremia (serum chloride >110 mmol/L) is quite common, with an incidence of 22%. Patients were propensity-matched based on their likelihood to develop acute postoperative hyperchloremia. Of the 4955 patients with hyperchloremia after surgery, 4266 (85%) patients were matched to patients who had normal serum chloride levels after surgery. These 2 groups were well balanced with respect to all variables collected. The hyperchloremic group was at increased risk of mortality at 30 days postoperatively (3.0% vs 1.9%; odds ratio = 1.58; 95% confidence interval, 1.25–1.98) (relative risk 1.6 or risk increase of 1.1%) and had a longer hospital stay (7.0 days [interquartile range 4.1–12.3] compared with 6.3 [interquartile range 4.0–11.3]) than patients with normal postoperative serum chloride levels. Patients with postoperative hyperchloremia were more likely to have postoperative renal dysfunction. Using all preoperative variables and measured outcome variables in a logistic regression analysis, hyperchloremia remained an independent predictor of 30-day mortality with an odds ratio of 2.05 (95% confidence interval, 1.62–2.59). CONCLUSION: This retrospective cohort trial demonstrates an association between hyperchloremia and poor postoperative outcome. Additional studies are required to demonstrate a causal relationship between these variables.

PREDICTORS OF MORBIDITY FOLLOWING FREE FLAP RECONSTRUCTION FOR CANCER OF THE HEAD AND NECK

Free flap reconstruction of head and neck cancer defects is complex with many factors that influence perioperative complications. The aim was to determine if there was an association between perioperative variables and postoperative outcome.

A multivariable model for predicting the need for blood transfusion in patients undergoing first-time elective coronary bypass graft surgery

BACKGROUND: The incidence of blood transfusion in coronary artery bypass graft (CABG) surgery remains high. Preoperative identification of those at high risk for requiring blood will allow for the cost‐effective use of some blood conservation modalities. Multivariable analysis techniques were used in this study to develop a prediction rule for such a purpose.

Real-time magnetic resonance imaging-guided focal laser therapy in patients with low-risk prostate cancer.

Two patients with low-risk prostate cancer (PCa) were treated with outpatient in-bore magnetic resonance imaging (MRI)-guided focal laser ablation. The tumor was identified on MRI. A laser fiber was delivered via a catheter inserted through a perineal template and guided to the target with MRI. The tissue temperature was monitored during laser ablation by MRI thermometry. Accumulated thermal damage was calculated in real time. Immediate post-treatment contrast-enhanced MRI confirmed devascularization of the target. No adverse events were noted. MRI-guided focal laser therapy of low-risk PCa is feasible and may offer a good balance between cancer control and side effects.

Does Tight Heart Rate Control Improve Beta-Blocker Efficacy? An Updated Analysis of the Noncardiac Surgical Randomized Trials

BACKGROUND: Recent meta-analyses assessing the efficacy of perioperative β-blockade trials have failed to show a reduction in postoperative morbidity and mortality. Tight control of heart rate (HR) has been suggested to improve these outcomes. Meta-analyses have not considered the influence of tight HR control on the efficacy of perioperative β-blockade. METHODS: Using previously published search strategies, we identified all randomized trials evaluating perioperative β-blockers after noncardiac surgery. This search yielded 10 trials with 2176 patients. We used the data from these studies to correlate measures of HR control with major postoperative outcomes, primarily in-hospital myocardial infarction (MI). Odds ratio (OR) and 95% confidence intervals (CI) were calculated, and metaregression was performed correlating measures of HR control with MI. RESULTS: The combined results of all studies did not show a significant cardioprotective effect of β-blockers, with considerable heterogeneity among the studies (OR = 0.76; 95% CI = 0.4–1.4; P = 0.38 heterogeneity: I2 = 34%). However, grouping the trials on the basis of maximal HR showed that trials where the estimated maximal HR was <100 bpm were associated with cardioprotection (OR = 0.23; 95% CI = 0.08–0.65; P = 0.005) whereas trials where the estimated maximal HR was >100 bpm did not demonstrate cardioprotection (OR = 1.17; 95% CI = 0.79–1.80; P = 0.43) with no heterogeneity. Moreover, metaregression of the HR response to β-blockade against the log OR of postoperative MI demonstrated a linear association between the effect of β-blockade on the mean, maximal, and variation in HR and the OR of an MI (r2 = 0.63; P < 0.001) where a larger effect of β-blockers on HR was associated with a decreased incidence of postoperative MI. Across all studies, β-blockade resulted in a reduction in postoperative HR (weighted mean difference: 8.6 bpm; 95% CI = −9.6 to −7.6; I2 = 85.3%) with considerable heterogeneity. This large heterogeneity in HR response to β-blockade was found to be related, in part, to the type of β-blocker, specifically, metoprolol, and the concomitant use of calcium channel blockers. Calcium channel blocker use and β-blockers other than metoprolol resulted in more effective control of HR. There was wide variability in the HR response to β-blockade. Twenty-five percent of patients receiving β-blockers had episodes when the HRs were more than 100 bpm, although 15% of placebo patients also had bradycardia, which would have required a dose reduction had they been administered β-blockers. Finally, this analysis found that perioperative β-blockade was associated with an increased incidence of bradycardia (OR = 3.49; 95% CI = 2.4–5.9) and congestive heart failure (OR = 1.68; 95% CI = 1.00–2.8). CONCLUSIONS: The trials that achieve the most effective control of HR are associated with a reduced incidence of postoperative MI, suggesting that effective control of HR is important for achieving cardioprotection. Second, this analysis demonstrates that administration of β-blockers does not reliably decrease HRs in all patients, and may be associated with increased side effects. Judicious use of combination therapy with other drugs may be necessary to achieve effective postoperative control of HR.