Leif Saager

Hospital Stay and Mortality Are Increased in Patients Having a "Triple Low" of Low Blood Pressure, Low Bispectral Index, and Low Minimum Alveolar Concentration of Volatile Anesthesia

Background: Low mean arterial pressure (MAP) and deep hypnosis have been associated with complications and mortality. The normal response to high minimum alveolar concentration (MAC) fraction of anesthetics is hypotension and low Bispectral Index (BIS) scores. Low MAP and/or BIS at lower MAC fractions may represent anesthetic sensitivity. The authors sought to characterize the effect of the triple low state (low MAP and low BIS during a low MAC fraction) on duration of hospitalization and 30-day all-cause mortality. Methods: Mean intraoperative MAP, BIS, and MAC were determined for 24,120 noncardiac surgery patients at the Cleveland Clinic, Cleveland, Ohio. The hazard ratios associated with combinations of MAP, BIS, and MAC values greater or less than a reference value were determined. The authors also evaluated the association between cumulative triple low minutes, and excess length-of-stay and 30-day mortality. Results: Means (±SD) defining the reference, low, and high states were 87 ± 5 mmHg (MAP), 46 ± 4 (BIS), and 0.56 ± 0.11 (MAC). Triple lows were associated with prolonged length of stay (hazard ratio 1.5, 95% CI 1.3–1.7). Thirty-day mortality was doubled in double low combinations and quadrupled in the triple low group. Triple low duration ≥60 min quadrupled 30-day mortality compared with ⩽15 min. Excess length of stay increased progressively from ⩽15 min to ≥60 min of triple low. Conclusions: The occurrence of low MAP during low MAC fraction was a strong and highly significant predictor for mortality. When these occurrences were combined with low BIS, mortality risk was even greater. The values defining the triple low state were well within the range that many anesthesiologists tolerate routinely.

Smoking and Perioperative Outcomes

Background:Patients are often concerned about the effects of smoking on perioperative risk. However, effective advice may be limited by the paucity of information about smoking and perioperative risk. Thus, our goal was to determine the effect of smoking on 30-day postoperative outcomes in noncardiac surgical patients. Methods:We evaluated 635,265 patients from the American College of Surgeons National Surgical Quality Improvement Program database; 520,242 patients met our inclusion criteria. Of these patients, 103,795 were current smokers; 82,304 of the current smokers were propensity matched with 82,304 never-smoker controls. Matched current smokers and never-smokers were compared on major and minor composite morbidity outcomes and respective individual outcomes. Results:Current smokers were 1.38 (95% CI, 1.11–1.72) times more likely to die than never smokers. Current smokers also had significantly greater odds of pneumonia (odds ratio [OR], 2.09; 95% CI, 1.80–2.43), unplanned intubation (OR, 1.87; 95% CI, 1.58–2.21), and mechanical ventilation (OR, 1.53; 95% CI, 1.31–1.79). Current smokers were significantly more likely to experience a cardiac arrest (OR, 1.57; 95% CI, 1.10–2.25), myocardial infarction (OR, 1.80; 95% CI, 1.11–2.92), and stroke (OR, 1.73; 95% CI, 1.18–2.53). Current smokers also had significantly higher odds of having superficial (OR, 1.30; 95% CI, 1.20–1.42) and deep (OR, 1.42; 95% CI, 1.21–1.68) incisional infections, sepsis (OR, 1.30; 95% CI, 1.15–1.46), organ space infections (OR, 1.38; 95% CI, 1.20–1.60), and septic shock (OR, 1.55; 95% CI, 1.29–1.87). Conclusion:Our analysis indicates that smoking is associated with a higher likelihood of 30-day mortality and serious postoperative complications. Quantification of increased likelihood of 30-day mortality and a broad range of serious smoking-related complications may enhance the clinicians ability to motivate smoking cessation in surgical patients.

Intraoperative Core Temperature Patterns, Transfusion Requirement, and Hospital Duration in Patients Warmed with Forced Air

Background:Core temperature patterns in patients warmed with forced air remain poorly characterized. Also unknown is the extent to which transient and mild intraoperative hypothermia contributes to adverse outcomes in broad populations. Methods:We evaluated esophageal (core) temperatures in 58,814 adults having surgery lasting >60 min who were warmed with forced air. Independent associations between hypothermic exposure and transfusion requirement and duration of hospitalization were evaluated. Results:In every percentile subgroup, core temperature decreased during the first hour and subsequently increased. The mean lowest core temperature during the first hour was 35.7 ± 0.6°C. Sixty-four percent of the patients reached a core temperature threshold of <36°C 45 min after induction; 29% reached a core temperature threshold of <35.5°C. Nearly half the patients had continuous core temperatures <36°C for more than an hour, and 20% of the patients were <35.5°C for more than an hour. Twenty percent of patients had continuous core temperatures <36°C for more than 2 h, and 8% of the patients were below 35.5°C for more than 2 h. Hypothermia was independently associated with both transfusions and duration of hospitalization, although the prolongation of hospitalization was small. Conclusions:Even in actively warmed patients, hypothermia is routine during the first hour of anesthesia. Thereafter, average core temperatures progressively increase. Nonetheless, intraoperative hypothermia was common, and often prolonged. Hypothermia was associated with increased transfusion requirement, which is consistent with numerous randomized trials.

Intraoperative transitions of anesthesia care and postoperative adverse outcomes.

Background:Transfers of patient care and responsibility among caregivers, “handovers,” are common. Whether handovers worsen patient outcome remains unclear. The authors tested the hypothesis that intraoperative care transitions among anesthesia providers are associated with postoperative complications. Methods:From the records of 138,932 adult Cleveland Clinic (Cleveland, Ohio) surgical patients, the authors assessed the association between total number of anesthesia handovers during a case and an adjusted collapsed composite of in-hospital mortality and major morbidities using multivariable logistic regression. Results:Anesthesia care transitions were significantly associated with higher odds of experiencing any major in-hospital mortality/morbidity (incidence of 8.8, 11.6, 14.2, 17.0, and 21.2% for patients with 0, 1, 2, 3, and ≥4 transitions; odds ratio 1.08 [95% CI, 1.05 to 1.10] for an increase of 1 transition category, P < 0.001). Care transitions among attending anesthesiologists and residents or nurse anesthetists were similarly associated with harm (odds ratio 1.07 [98.3% CI, 1.03 to 1.12] for attending [incidence of 9.4, 13.9, 17.4, and 21.5% for patients with 0, 1, 2, and ≥3 transitions] and 1.07 [1.04 to 1.11] for residents or nurses [incidence of 9.4, 13.0, 15.4, and 21.2% for patients with 0, 1, 2, and ≥3 transitions], both P < 0.001). There was no difference between matched resident only (8.5%) and nurse anesthetist only (8.8%) cases on the collapsed composite outcome (odds ratio, 1.00 [98.3%, 0.93 to 1.07]; P = 0.92). Conclusion:Intraoperative anesthesia care transitions are strongly associated with worse outcomes, with a similar effect size for attendings, residents, and nurse anesthetists.

A Nomogram for Predicting Surgical Complications in Bariatric Surgery Patients

BackgroundTo minimize morbidity and mortality associated with surgery risks in the obese patient, algorithms offer planning operative strategy. Because these algorithms often classify patients based on inadequate category granularity, outcomes may not be predicted accurately. We reviewed patient factors and patient outcomes for those who had undergone bariatric surgical procedures to determine relationships and developed a nomogram to calculate individualized patient risk.MethodsFrom the American College of Surgeons National Security Quality Improvement Program database, we identified 32,426 bariatric surgery patients meeting NIH criteria and treated between 2005 and 2008. We defined a composite binary outcome of 30-day postoperative morbidity and mortality. A predictive model based on preoperative variables was developed using multivariable logistic regression; a multiple imputation procedure allowed inclusions of observations with missing data. Model performance was assessed using the C-statistic. A calibration plot graphically assessed the agreement between predicted and observed probabilities in regard to 30-day morbidity/mortality.ResultsThe nomogram model was constructed for maximal predictive accuracy. The estimated C-statistic [95% confidence interval] for the predictive nomogram was 0.629 [0.614, 0.645], indicative of slight to moderate discriminative ability beyond that of chance alone, and the greatest impacts on the estimated probability of morbidity/mortality were determined to be age, body mass index, serum albumin, and functional status.ConclusionsBy accurately predicting 30-day morbidity and mortality, this nomogram may prove useful in patient preoperative counseling on postoperative complication risk. Our results additionally indicate that neither age nor presence of obesity-related comorbidities should exclude patients from bariatric surgery consideration.

Angiotensin converting enzyme inhibitors are not associated with respiratory complications or mortality after noncardiac surgery

BACKGROUND: General use of angiotensin-converting enzyme inhibitors (ACEIs) is associated with upper-airway complications such as cough, angioedema, and bronchospasm; furthermore, preoperative use is associated with increased morbidity or mortality. Our primary goal in this study was thus to evaluate the association of ACEI therapy with perioperative respiratory morbidity in adult noncardiac surgical patients. Our secondary goals were to evaluate the association between preoperative use of ACEI and 30-day mortality, as well as to a composite outcome of in-hospital morbidity and mortality in adult noncardiac surgical patients having general anesthesia. METHODS: We evaluated 79,228 patients (9905 ACEI users [13] and 66,620 [87%] non-ACEI users) who had noncardiac surgery at the Cleveland Clinic between 2005 and 2009. Propensity matching successfully paired 9028 ACEI users (91% of 9905 patients) with 9028 controls. Matched intraoperative ACEI users and non-ACEI users were compared on intraoperative and postoperative respiratory morbidity composites as well as individual complications, 30-day mortality, and a composite of in-hospital morbidity and mortality. RESULTS: The association between ACEI use and respiratory morbidity composites was not statistically significant intraoperatively (OR: 1.09 [97.5% CI: 0.91, 1.31], ACEI versus non-ACEI; P = 0.28) or postoperatively (OR: 0.97 [97.5% CI: 0.81, 1.16], ACEI versus non-ACEI; P = 0.69). Within the propensity-matched subset, ACEI usage was not associated with either 30-day mortality (OR: 0.93 [95% CI: 0.73, 1.19], ACEI versus non-ACEI; P = 0.56) or the composite of in-hospital morbidity and mortality (OR: 1.06 [95% CI: 0.97, 1.15], ACEI versus non-ACEI; P = 0.22). We also observed that the ACEI and the non-ACEI groups were descriptively similar (standardized differences <0.03) on multiple time periods of intraoperative hemodynamic characteristics, vasopressor use, and colloid and crystalloid infusions. CONCLUSIONS: We did not find any association between use of ACEIs and intraoperative or postoperative upper-airway complications. Furthermore, ACEI use was not associated with in-hospital complications or increased 30-day mortality.

The association between nitrous oxide and postoperative mortality and morbidity after noncardiac surgery.

BACKGROUND:Nitrous oxide (N2O) has been widely used in clinical anesthesia for >150 years. However, use of N2O has decreased in recent years because of concern about the drug’s metabolic side effects. But evidence that routine use of N2O causes clinically important toxicity remains elusive. We therefore evaluated the relationship between intraoperative N2O administration and 30-day mortality as well as a set of major inpatient postoperative complications (including mortality) in adults who had general anesthesia for noncardiac surgery. METHODS:We evaluated 49,016 patients who had noncardiac surgery at the Cleveland Clinic between 2005 and 2009. Among 37,609 qualifying patients, 16,961 were given N2O (“nitrous,” 45%) and 20,648 were not (“nonnitrous,” 55%). Ten thousand seven hundred fifty-five nitrous patients (63% of the total) were propensity score-matched with 10,755 nonnitrous patients. Matched nitrous and nonnitrous patients were compared on 30-day mortality and a set of 8 in-hospital morbidity/mortality outcomes. RESULTS:Inhalation of N2O intraoperatively was associated with decreased odds of 30-day mortality (odds ratio [OR]: 97.5% confidence interval, 0.67, 0.46–0.97; P = 0.02). Furthermore, nitrous patients had an estimated 17% (OR: 0.83, 0.74–0.92) decreased odds of experiencing major in-hospital morbidity/mortality than nonnitrous (P < 0.001). Among the individual morbidities, intraoperative N2O use was only associated with significantly lower odds of having pulmonary/respiratory morbidities (OR, 95% Bonferroni-adjusted CI: 0.59, 0.44–0.78). CONCLUSIONS:Intraoperative N2O administration was associated with decreased odds of 30-day mortality and decreased odds of in-hospital mortality/morbidity. Aside from its specific and well-known contraindications, the results of this study do not support eliminating N2O from anesthetic practice.

The association between preoperative anemia and 30-day mortality and morbidity in noncardiac surgical patients

BACKGROUND:Anemia has been associated with increased postoperative morbidity and mortality. We used the American College of Surgeons National Surgical Quality Improvement Program database to retrospectively assess the relationship between preoperative anemia and 30-day postoperative mortality and morbidity in noncardiac surgical patients, careful to distinguish confounding variables from mediator variables. METHODS:Each patient with preoperative anemia was matched to one without anemia using propensity matching on potentially confounding baseline variables. Logistic regression was used to evaluate the relationship between preoperative anemia and 30-day postoperative mortality and morbidity. The primary hypothesis was evaluated after adjusting for covariables showing residual imbalance after matching. RESULTS:Within the database, 574,860 of 971,455 surgical cases met our inclusion criteria, and among those 145,218 (25.3%) were anemic at baseline. The unadjusted odds ratio (95% confidence interval) for 30-day mortality comparing anemic patients with nonanemic patients was 4.69 (4.01–5.49). Among the propensity-matched group of 238,596 patients, the total effect (i.e., not adjusting for mediator variables) of preoperative anemia was estimated as an odds ratio of 1.59 (1.42–1.78). After adjusting for suspected mediator variables, preoperative anemia was only weakly associated with an odds ratio of 1.24 (1.10–1.40) for 30-day mortality. CONCLUSION:Preoperative anemia appears to be associated with baseline diseases that markedly increase mortality. Anemia per se is a rather weak independent predictor of postoperative mortality. Our analysis also illustrates how analyzing large variable-rich registries challenges investigators to discriminate between confounding variables and mediator variables, i.e., factors that might be considered as “causal pathways” for the effect of the exposure or intervention on outcome.

Erythrocyte storage duration is not associated with increased mortality in noncardiac surgical patients: a retrospective analysis of 6,994 patients.

Background:More than 5 million patients receive erythrocyte transfusions in the United States every year. Previous studies linked the storage duration of allogeneic erythrocytes to the risk of severe postoperative complications, especially after cardiac or trauma surgery. Limited data are available for noncardiac surgical patients. We therefore evaluated the association between storage duration of transfused erythrocytes and postoperative all-cause mortality among general surgery patients. Methods:Perioperative data corresponding to 63,319 adult, general surgery patients were obtained from our registry and merged with blood product data. Patients receiving solely leukocyte-reduced, allogeneic erythrocyte transfusions were included. Multivariable Cox proportional hazards regression was used to characterize the relationship between median erythrocyte storage duration and postoperative mortality rate, adjusting for characteristics plausibly influencing the storage duration of erythrocytes. Results:Of the 6,994 patients included in the final analysis, 23, 44, 11, 9, and 13% received 1, 2, 3, 4, and ≥5 erythrocyte units, respectively. The authors found no evidence that increasing median storage duration was associated with a difference in the risk of postoperative mortality (hazard ratio, 0.99 [0.94–1.04]; P = 0.64). Analyzing the mean storage duration of erythrocyte units as a function of year of transfusion, the authors demonstrate a relevant decrease in utilization of the oldest blood units, whereas young blood storage duration remains nearly unchanged. Conclusion:The authors’ study supports the recent literature in surgical and medical patients and underlines the importance of sufficiently powered randomized trials to finally resolve the erythrocyte storage duration debate.

Operation timing and 30-day mortality after elective general surgery.

BACKGROUND: Human factors such as fatigue, circadian rhythms, scheduling, and staffing may have an impact on patient care over the course of a day across all medical specialties. Research by the transportation industry concludes that human performance is degraded by shift work, circadian rhythm disturbances, and prolonged duty. We investigated whether the timing of general surgery (specifically, increasing time of day, increasing day of week, July/August cases versus other months), and moon phase is independently related to 30-day mortality. A secondary outcome of composite in-hospital complications was also evaluated. METHODS: The binary outcomes of 32,001 elective general surgical patients at the Cleveland Clinic between January 2005 and September 2010 were analyzed according to the hour of the day (6 am to 7 pm), day of the workweek, month of the year, and moon phase in which the surgery started. Thirty-day mortality was modeled as a binary endpoint using a multivariable logistic regression, adjusting for a risk stratification index based on International Classification of Diseases (9th rev.) codes. RESULTS: The adjusted odds ratio ([Bonferroni-adjusted 95% CI]) associated with a relative increase in time of day of 4 h was 1.23 [0.91, 1.67], P = 0.09. Similarly, no association was found for day of week (0.99 [0.83, 1.17]) for a relative increase of 1 day, P = 0.85. Mortality was not significantly more frequent in July and August than in other months (adjusted odds ratio = 0.72 [0.36, 1.43], P = 0.22). Moon phase was not significantly related to mortality (P = 0.72). There were also no significant time-dependent differences in composite complications. CONCLUSIONS: Elective general surgery appears to be comparably safe at any time of the workday, any day of the workweek, and in any month of the year.