Risk of respiratory failure after repair of thoracoabdominal aortic aneurysms

Predictors of Failure to Rescue After Postoperative Respiratory Failure: A Retrospective Cohort Analysis of 13,047 Patients Using the ACS-NSQIP Dataset

INTRODUCTION

Death after suffering a postoperative complication (failure to rescue) is an area of concern, and its occurrence after postoperative respiratory failure (PRF) is not well defined. We seek to identify the predictors of failure to rescue in patients who develop PRF.

METHODS

A retrospective cohort study of adults undergoing noncardiac surgery who developed PRF (postoperative unplanned intubation and receipt of mechanical ventilation for longer than 48 h) was conducted using the American College of Surgeons National Surgical Quality Improvement Project database. Predictors of failure to rescue after PRF were identified using the Least Absolute Shrinkage and Selection Operator (LASSO)-penalized variable selection method, with the Bayesian information criterion, in the context of a multiple logistic regression model (with Firth's bias correction).

RESULTS

Of the 13,047 patients that formed our final evaluable study cohort, 3669 (28.1%) patients died within 30 days of surgery. We identified age, sex, American Society of Anesthesiologists physical status, presence of preoperative ascites, disseminated cancer, bleeding disorders, elevated preoperative creatinine, and low preoperative prealbumin levels as predictors of failure to rescue. The area under the curve for the final model was 0.6804, with a standard error of 0.0104 (95% CI area under the curve: 0.6600 to 0.7008).

CONCLUSIONS

We observed that almost 30% of patients that develop respiratory failure after noncardiac surgery die within 30 days of surgery. The validated eight-variable perioperative predictive model provides a risk estimate for death after PRF and may be useful for the purposes of preoperative planning, prognostication, decision making and resource allocation in patients who develop this complication.

Machine learning model for predicting immediate postoperative desaturation using spirometry signal data

Postoperative desaturation is a common post-surgery pulmonary complication. The real-time prediction of postoperative desaturation can become a preventive measure, and real-time changes in spirometry data can provide valuable information on respiratory mechanics. However, there is a lack of related research, specifically on using spirometry signals as inputs to machine learning (ML) models. We developed an ML model and postoperative desaturation prediction index (DPI) by analyzing intraoperative spirometry signals in patients undergoing laparoscopic surgery. We analyzed spirometry data from patients who underwent laparoscopic, robot-assisted gynecologic, or urologic surgery, identifying postoperative desaturation as a peripheral arterial oxygen saturation level below 95%, despite facial oxygen mask usage. We fitted the ML model on two separate datasets collected during different periods. (Datasets A and B). Dataset A (Normal 133, Desaturation 74) was used for the entire experimental process, including ML model fitting, statistical analysis, and DPI determination. Dataset B (Normal 20, Desaturation 4) was only used for verify the ML model and DPI. Four feature categories-signal property, inter-/intra-position correlation, peak value/interval variability, and demographics-were incorporated into the ML models via filter and wrapper feature selection methods. In experiments, the ML model achieved an adequate predictive capacity for postoperative desaturation, and the performance of the DPI was unbiased.

Pulmonary prehabilitation and smoking cessation

PURPOSE OF REVIEW

This review aims to summarize the current literature on pulmonary prehabilitation programs, their effects on postoperative pulmonary complications, and the financial implications of implementing these programs. Additionally, this review has discussed the current trends in pulmonary prehabilitation programs, techniques for improving rates of perioperative smoking cessation, and the optimal timing of these interventions.

RECENT FINDINGS

Prehabilitation is a series of personalized multimodal interventions tailored to individual needs, including lifestyle and behavioral measures. Pulmonary prehabilitation has shown to reduce postoperative pulmonary complications (PPCs).

SUMMARY

The implications of clinical practice and research findings regarding PPCs are an increased burden of postoperative complications and financial cost to both patients and hospital systems. There is convincing evidence that pulmonary prehabilitation based on endurance training should be started 8-12 weeks prior to major surgery; however, similar rates of improved postoperative outcomes are observed with high-intensity interval training (HIIT) for 1-2 weeks. This shorter interval of prehabilitation may be more appropriate for patients awaiting thoracic surgery, especially for cancer resection. Additionally, costs associated with creating and maintaining a prehabilitation program are mitigated by shortened lengths of stay and reduced PPCs. Please see Video Abstract, http://links.lww.com/COAN/A90.

A Supraceliac Aortic Cross Clamping Model to Explore Remote Lung Injury and the Endothelial Glycocalyx

BACKGROUND

We hypothesized that supraceliac aortic cross clamping could induce lung injury mediated by an inflammatory ischemia-reperfusion (IR) trigger. We aimed to characterize glycocalyx (GCX), a component of endothelial membrane, participating to remote lung injury.

METHODS

Rats underwent supraceliac aortic cross clamping for 40 min and were sacrificed at 0, 3, 6, and 24 hr of reperfusion (n = 10/group). Each group was compared to sham (n = 6/group). GCX products (syndecan-1 [Sdc-1] and heparan sulfate [HS]), tumor necrosis factor-alpha (TNF-α), and interleukin-1β (IL-1β) were measured in plasma (enzyme-linked immunosorbent assay[ELISA]). Lungs were harvested for measurements of TNF-α, IL-1β (polymerase chain reaction) and Sdc-1 (western blotting [WB]). Histologic lung injury scoring and pulmonary gravimetry were analyzed in a blinded manner.

RESULTS

Plasmatic Sdc-1, HS, TNF-α, and IL-1β reached peak levels at 3 hr. Levels were significantly higher in clamping groups than sham at 6 hr for Sdc-1, at 0 and 3 hr for HS, at 3 and 6 hr for TNF-α, and at 3 hr for IL-1β. Lung TNF-α and Interleukin-1β reached peak levels at 6 hr. Levels were significantly higher than sham at 6 and 24 hr for TNF-α and at 6 hr for IL-1β. Lung Sdc-1 was lowest at 3 hr. Sdc-1 was not significantly different compared to sham at the different reperfusion times. At 3 hr, it was 0.27 ± 0.03 vs. 0.33 ± 0.02 (sham) (P = 0.09). Histopathologic scores at 6 and 24 hr were higher in clamping groups than sham. At 6 and 24 hr, it was higher for hemorrhage, polynuclear neutrophil (PNN) infiltration and intravascular leukocytes. Pulmonary edema was higher by gravimetry at 0 and 6 hr.

CONCLUSIONS

Supra celiac aortic clamping causes early lung injury in relation with a systemic inflammatory response associated with altered GCX structure.

Outcomes and risk factors for delayed-onset postoperative respiratory failure: a multi-center case-control study by the University of California Critical Care Research Collaborative (UC3RC)

BACKGROUND

Few interventions are known to reduce the incidence of respiratory failure that occurs following elective surgery (postoperative respiratory failure; PRF). We previously reported risk factors associated with PRF that occurs within the first 5 days after elective surgery (early PRF; E-PRF); however, PRF that occurs six or more days after elective surgery (late PRF; L-PRF) likely represents a different entity. We hypothesized that L-PRF would be associated with worse outcomes and different risk factors than E-PRF.

METHODS

This was a retrospective matched case-control study of 59,073 consecutive adult patients admitted for elective non-cardiac and non-pulmonary surgical procedures at one of five University of California academic medical centers between October 2012 and September 2015. We identified patients with L-PRF, confirmed by surgeon and intensivist subject matter expert review, and matched them 1:1 to patients who did not develop PRF (No-PRF) based on hospital, age, and surgical procedure. We then analyzed risk factors and outcomes associated with L-PRF compared to E-PRF and No-PRF.

RESULTS

Among 95 patients with L-PRF, 50.5% were female, 71.6% white, 27.4% Hispanic, and 53.7% Medicare recipients; the median age was 63 years (IQR 56, 70). Compared to 95 matched patients with No-PRF and 319 patients who developed E-PRF, L-PRF was associated with higher morbidity and mortality, longer hospital and intensive care unit length of stay, and increased costs. Compared to No-PRF, factors associated with L-PRF included: preexisiting neurologic disease (OR 4.36, 95% CI 1.81-10.46), anesthesia duration per hour (OR 1.22, 95% CI 1.04-1.44), and maximum intraoperative peak inspiratory pressure per cm H₂0 (OR 1.14, 95% CI 1.06-1.22).

CONCLUSIONS

We identified that pre-existing neurologic disease, longer duration of anesthesia, and greater maximum intraoperative peak inspiratory pressures were associated with respiratory failure that developed six or more days after elective surgery in adult patients (L-PRF). Interventions targeting these factors may be worthy of future evaluation.

Novel application of respiratory muscle index obtained from chest computed tomography to predict postoperative respiratory failure after major non-cardiothoracic surgery

BACKGROUND

Postoperative respiratory failure (PRF) is a serious complication associated with significant morbidity and mortality. We propose a new method to predict PRF by utilizing computed tomography (CT) of the chest to assess degree of respiratory muscle wasting prior to surgery.

METHODS

Patients who received a chest CT and required invasive mechanical ventilation (MV) after major non-cardiothoracic surgery were included. Exclusion criteria included cardiothoracic surgery. Respiratory muscle index (RMI) was calculated at the T6 vertebra measured on Slice-O-Matic® software.

RESULTS

Thirty three patients met inclusion with a mean (±SD) age, BMI, and APACHE II score of 62.2 years (±12.1), 28.1 kg/m² (±7.8), and 14.1 (±4.7). Most patients were female (n = 22 [67%]). Eleven patients (33%) developed PRF with a mean of 6.0 (±10.7) initial ventilation days. There was no difference in baseline demographics between groups. RMI values for the PRF group were significantly lower when compared to the non-PRF group: 22.7 cm²/m² (±5.3) vs. 28.5 cm²/m² (±5.9) (p = 0.008).

CONCLUSION

Presence of respiratory muscle wasting prior to surgery was found to be associated with postoperative respiratory failure.

Respiratory Failure after Open Descending Aortic Aneurysm Repair: Risk Factors and Outcomes

Purpose: This study was conducted to identify predictors of respiratory failure after open repair of descending thoracic aortic aneurysm (DTAA), and to identify any relationship between respiratory failure and long-term survival.

Methods: A total of 75 patients undergoing elective open DTAA repair at the Shiga University of Medical Science Hospital were included in the study. Univariate and multivariate logistic regression analyses were performed to assess the odds ratios for incident postoperative respiratory failure after open DTAA repair. Survival over time was estimated by the Kaplan–Meier method.

Results: Respiratory failure, defined as ventilation dependence for longer than 48 hours, occurred in 11 patients (14.7%). Independent predictors of respiratory failure after DTAA included prolonged operation time and reduced preoperative forced expiratory volume in 1 second/forced vital capacity × 100 (FEV₁%). In-hospital mortality was higher (p = 0.020) among patients with respiratory failure (18.2% of those who suffered respiratory failure) than among those without (0%). The survival rates at 8 years were significantly lower (p = 0.010) in the respiratory failure group (at 44.2%) than in the group without respiratory failure (at 89.0%).

Conclusion: Lower FEV₁% and longer operation time were risk factors of postoperative respiratory failure after open repair of DTAA, which in turn is associated with significantly reduced long-term survival.

Diaphragm Preservation Reduces Respiratory Failure After Extent I Thoracoabdominal Aneurysm Repair

BACKGROUND

We sought to evaluate the impact of surgical approach (thoracophrenolaparotomy vs thoracotomy crura splitting) on the outcomes of extent I thoracoabdominal aortic aneurysm repair.

METHODS

Patient data were extracted from our aortic surgery database. The primary endpoint was need for tracheostomy, and secondary endpoints were operative mortality, myocardial infarction, stroke, spinal cord injury, de novo dialysis, and major adverse events (composite of secondary endpoints and tracheostomy). Freedom from death and reoperation during follow-up were calculated. Risk adjustment was obtained with propensity score matching and multivariable regression.

RESULTS

Three hundred twenty-five patients underwent extent I repair. Compared with thoracophrenolaparotomy patients (n = 226), thoracotomy crura-splitting patients (n = 99) had a higher rate of previous coronary revascularization (27.3% vs 14.2%, P = .005), valvular disease (64.6% vs 50.4%, P = .018), and chronic obstructive pulmonary disease (61.6% vs 28.3%, P = .000) and a lower forced expiratory volume in 1 second (46% vs 69%, P = .000). In a matched sample thoracotomy crura splitting was associated with a decreased need for tracheostomy (4.0% vs 13.1%, P = .035). The need for tracheostomy was predicted by female gender (odds ratio, 3.11; 95% confidence interval, 1.17-8.30; P = .023), forced expiratory volume in 1 second (odds ratio, 0.95; 95% confidence interval, 0.91-0.98; P = .003), and thoracophrenolaparotomy (odds ratio, 3.66; 95% confidence interval, 1.14-11.73; P = .029). Five-year freedom from mortality and reoperation were similar.

CONCLUSIONS

In patients undergoing extent I thoracoabdominal aortic aneurysm repair, thoracotomy crura splitting was associated with decreased need for tracheostomy.

Impact of Prognostic Nutritional Index on Postoperative Pulmonary Complications in Radical Cystectomy: A Propensity Score-Matched Analysis

BACKGROUND

Radical cystectomy is a standard treatment for muscle-invasive bladder cancer but frequently entails postoperative pulmonary complications (PPCs). Nutrition is closely associated with postoperative outcomes. Therefore, we evaluated the impact of preoperative prognostic nutritional index (PNI) on PPCs in radical cystectomy.

METHODS

PNI was calculated as 10 × (serum albumin) + 0.005 × (total lymphocyte count). The risk factors for PPCs were evaluated using multivariate logistic regression analysis. A receiver operating characteristic curve analysis of PNI was performed, and an optimal cut-off value was identified. Propensity score-matched analysis was used to determine the impact of PNI on PPCs. Postoperative outcomes were also evaluated.

RESULTS

PPCs occurred in 112 (13.6%) of 822 patients. Multivariate logistic regression analysis identified PNI, age, and serum creatinine level as risk factors. The area under the receiver operating characteristic curve of PNI for predicting PPCs was 0.714 (optimal cut-off value: 45). After propensity score matching, the incidence of PPCs in the PNI ≤ 45 group was significantly higher compared with the PNI > 45 group (20.8% vs. 6.8%; p < 0.001), and PNI ≤ 45 was associated with a higher incidence of PPCs (odds ratio 3.308, 95% confidence interval 1.779-6.151; p < 0.001). The rates of intensive care unit admission and prolonged (> 2 days) stay thereof were higher in patients who developed PPCs.

CONCLUSIONS

Preoperative PNI ≤ 45 was associated with a higher incidence of PPCs in radical cystectomy, suggesting that PNI provides useful information regarding pulmonary complications after radical cystectomy.

Bypass Techniques for Descending Thoracic Aortic Surgery

The conduct of partial left heart bypass or partial car diopulmonary bypass (CPB) during surgery involving the descending thoracic aorta or thoracoabdominal aorta is one of the most unappreciated and misunder stood extracorporeal circulation procedures in cardio vascular surgery. It is different from conventional CPB, and although some uninitiated practitioners consider it simpler, it is in fact more complicated than conven tional CPB and involves different concepts. It requires expertise and skill in regulating the flow, pressure, and oxygenation of blood going to both the proximal and distal parts of the body and management of the special bypass or shunt procedures used, specialized monitor ing, and knowledge about the protection and preserva tion of organs both proximal and distal to the aortic clamping. It demands exquisite communication and un derstanding of the unique problems faced by the sur geon, anesthesiologist, and perfusionist.

Development and validation of a score to predict postoperative respiratory failure in a multicentre European cohort: A prospective, observational study

BACKGROUND

Postoperative respiratory failure (PRF) is the most frequent respiratory complication following surgery.

OBJECTIVE

The objective of this study was to build a clinically useful predictive model for the development of PRF.

DESIGN

A prospective observational study of a multicentre cohort.

SETTING

Sixty-three hospitals across Europe.

PATIENTS

Patients undergoing any surgical procedure under general or regional anaesthesia during 7-day recruitment periods.

MAIN OUTCOME MEASURES

Development of PRF within 5 days of surgery. PRF was defined by a partial pressure of oxygen in arterial blood (PaO2) less than 8 kPa or new onset oxyhaemoglobin saturation measured by pulse oximetry (SpO2) less than 90% whilst breathing room air that required conventional oxygen therapy, noninvasive or invasive mechanical ventilation.

RESULTS

PRF developed in 224 patients (4.2% of the 5384 patients studied). In-hospital mortality [95% confidence interval (95% CI)] was higher in patients who developed PRF [10.3% (6.3 to 14.3) vs. 0.4% (0.2 to 0.6)]. Regression modelling identified a predictive PRF score that includes seven independent risk factors: low preoperative SpO2; at least one preoperative respiratory symptom; preoperative chronic liver disease; history of congestive heart failure; open intrathoracic or upper abdominal surgery; surgical procedure lasting at least 2 h; and emergency surgery. The area under the receiver operating characteristic curve (c-statistic) was 0.82 (95% CI 0.79 to 0.85) and the Hosmer-Lemeshow goodness-of-fit statistic was 7.08 (P = 0.253).

CONCLUSION

A risk score based on seven objective, easily assessed factors was able to predict which patients would develop PRF. The score could potentially facilitate preoperative risk assessment and management and provide a basis for testing interventions to improve outcomes.The study was registered at ClinicalTrials.gov (identifier NCT01346709).

Endoluminal Repair of Aneurysms Containing Ostia of Essential Branch Arteries: An Experimental Model

Purpose:

To examine experimentally the feasibility of transfemoral endoluminal repair of aneurysms containing the ostia of essential branch arteries.

Methods:

In a canine model (n = 4), suprarenal aortic aneurysms were created by suturing an artificial patch onto an anterior arteriotomy. Following a 2-week recovery period, the dogs underwent endovascular exclusion of their aneurysms using an aortic stent-graft with separate renal artery branch grafts. Outcome was evaluated using angiography, intravascular ultrasound (IVUS), Doppler flow, invasive pressure monitoring, and autopsy, respectively.

Results:

Successful creation and subsequent endovascular exclusion of the aneurysm using aortic stent-grafts and separate bilateral renal artery stent-grafts was achieved in all trials. Angiographically, all aneurysms were excluded from aortic flow and all renal arteries were patent at completion of the procedure. With IVUS, good graft apposition and absence of perigraft flow were demonstrated in all animals. Mean pressure in the aneurysmal sac at completion of the procedure was 40 ± 7 mmHg, compared to a mean systemic blood pressure of 105 ± 8 mmHg (p < 0.05). At autopsy, no gross intimal damage was seen in the aorta or the renal arteries, and intact aortic grafts and branch grafts without twisting, coiling, or kinking were found in all trials.

Conclusions:

In an acute animal model, suprarenal aortic aneurysms can be excluded from the circulation with preservation of renal flow using an endoluminally placed aortic stent-graft with separate branch grafts.

Impact of GOLD groups of chronic pulmonary obstructive disease on surgical complications

Purpose

Chronic obstructive pulmonary disease (COPD) is associated with increased postoperative complications. Recently, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classified COPD patients into four groups based on spirometry results and the severity of symptoms. The objective of this study was to evaluate the impact of GOLD groups on postoperative complications.

Patients and methods

We reviewed the medical records of COPD patients who underwent preoperative spirometry between April and August 2013 at a tertiary hospital in Korea. We divided the patients into GOLD groups according to the results of spirometry and self-administered questionnaires that assessed the symptom severity and exacerbation history. GOLD groups, demographic characteristics, and operative conditions were analyzed.

Results

Among a total of 405 COPD patients, 70 (17.3%) patients experienced various postoperative complications, including infection, wound, or pulmonary complications. Thoracic surgery, upper abdominal surgery, general anesthesia, large estimated blood loss during surgery, and longer anesthesia time were significant risk factors for postoperative complications. Patients in high-risk group (GOLD groups C or D) had an increased risk of postoperative complications compared to those in low-risk group (GOLD groups A or B).

Conclusion

COPD patients in GOLD groups representing a high exacerbation risk have an increased risk of postoperative complications compared to those with low risk.

Frequency Rate of Atelectasis in Patients Following Coronary Artery Bypass Graft and Its Associated Factors at Mazandaran Heart Center in 2013-2014

INTRODUCTION

As the most common postoperative pulmonary complications after cardiac surgery, atelectasis is one of the most important and serious early postoperative complications and one of the most important causes of prolonged hospitalization, increased costs, and mortality rise. Therefore, the present study was aimed at specifying the frequency of atelectasis in patients following coronary artery bypass graft and its associated factors in Mazandaran Heart Center in 2013-2014.

MATERIALS

The present investigation was a descriptive cross-sectional study in which sequential sampling was used. It was conducted on 375 patients whose coronary artery bypass graft had been performed by the same surgeon and anesthesiologist. For data collection, first the patients' demographic variables and the information of their surgery were retrieved through their profiles, direct observation, patient inquiry, and the collected data were recorded in the data collection forms. Then, atelectasis was measured before the surgery and on the first and second days after it by taking CXR whose results were checked by two radiologists who were not aware of the previous observations. Data were analyzed through t-test, Pearson test, and Chi-square test using SPSS 16.0.

RESULTS

The results of the present study indicated that, 123 out of 375 patients (32.8%) were diagnosed with at least one type of tattletales during the first three days after the surgery. The mean age of the patients who were diagnosed with atelectasis was 62.9 and most of them were female. The results also showed that there was a significant relationship between postoperative frequency of atelectasis and the patients' pulmonary diseases and underlying diseases like diabetes and hyperlipidemia, smoking and alcohol use before the surgery, and transfusion of 4 units of packed red blood cells during the surgery (p<0.05).

CONCLUSION

Atelectasis is the most common postoperative complication which emerges more in patients with pulmonary and underlying diseases than other patients.

Noninvasive ventilation in pediatric emergency care: a literature review and description of our experience

Noninvasive ventilation (NIV) refers to a kind of mechanical respiratory support used in order to avoid the progression of respiratory failure to endotracheal intubation. Even though if this method is widely known in patients affected by chronic diseases and in children admitted in pediatric and neonatal intensive care units, few data are actually available on its use in intermediate care units. The present review focuses on the efficiency of NIV performed in children with acute respiratory failure due to different conditions. Moreover, the authors have described their experience with NIV in pediatric patients admitted to their acute and emergency room where NIV was started, well tolerated and led to an improvement of gas exchanges, decreasing the muscular respiratory work and endotracheal intubation avoidance in most of the patients.

Novel use of a gastrointestinal stapler for diaphragm division during thoracoabdominal aortic exposure

A significant portion of the morbidity associated with a thoracoabdominal approach to the suprarenal aorta is due to postoperative pulmonary dysfunction. A contributing factor to this dysfunction is division of the diaphragm during surgical exposure and subsequent repair upon completion of the operation. In this brief technical report, we describe a novel technique using a gastrointestinal stapler to divide the diaphragm that is rapid, hemostatic, and aids with reapproximation at the completion of the case. This method of diaphragm division is quicker and less traumatic and has the potential to decrease the incidence of postoperative pulmonary dysfunction.

Postoperative Respiratory Muscle Dysfunction

Postoperative pulmonary complications are responsible for significant increases in hospital cost as well as patient morbidity and mortality; respiratory muscle dysfunction represents a contributing factor. Upper airway dilator muscles functionally resist the upper airway collapsing forces created by the respiratory pump muscles. Standard perioperative medications (anesthetics, sedatives, opioids, and neuromuscular blocking agents), interventions (patient positioning, mechanical ventilation, and surgical trauma), and diseases (lung hyperinflation, obesity, and obstructive sleep apnea) have differential effects on the respiratory muscle subgroups. These effects on the upper airway dilators and respiratory pump muscles impair their coordination and function and can result in respiratory failure. Perioperative management strategies can help decrease the incidence of postoperative respiratory muscle dysfunction. Such strategies include minimally invasive procedures rather than open surgery, early and optimal mobilizing of respiratory muscles while on mechanical ventilation, judicious use of respiratory depressant anesthetics and neuromuscular blocking agents, and noninvasive ventilation when possible.

Variation in academic medical centers' coding practices for postoperative respiratory complications: implications for the AHRQ postoperative respiratory failure Patient Safety Indicator

BACKGROUND

The Agency for Healthcare Research and Quality Patient Safety Indicator (PSI) 11 uses International Classification of Disease, 9th Clinical Modification diagnosis code 518.81 ("Acute respiratory failure")-but not the closely related alternative, 518.5 ("Pulmonary insufficiency after trauma and surgery")-to detect cases of postoperative respiratory failure. We sought to determine whether hospitals vary in the use of 518.81 versus 518.5 and whether such variation correlates with coder beliefs.

STUDY DESIGN

We conducted a cross-sectional analysis of administrative data from July 2009 through June 2010 for UHC (formerly University HealthSystem Consortium)-affiliated centers to assess the use of diagnosis codes 518.81 and 518.5 in PSI 11-eligible cases. We also surveyed coders at these centers to evaluate whether variation in the use of 518.81 versus 518.5 might be linked to coder beliefs. We asked survey respondents which diagnosis they would use for 2 ambiguous cases of postoperative pulmonary complications and how much they agreed with 6 statements about the coding process.

RESULTS

UHC-affiliated centers demonstrated wide variation in the use of 518.81 and 518.5, ranging from 0 to 26 cases and 0 to 56 cases/1000 PSI 11-eligible hospitalizations, respectively. Of 56 survey respondents, 64% chose 518.81 and 30% chose 518.5 for a clinical scenario involving postoperative respiratory failure, but these responses were not associated with actual coding of 518.81 or 518.5 at the center level. Sixty-two percent of respondents agreed that they are constrained by the words that physicians use. Their self-reported likelihood of querying physicians to clarify the diagnosis was significantly associated with coding of 518.5 at the center level.

CONCLUSIONS

The extent to which diagnosis code 518.81 is used relative to 518.5 varies considerably across centers, based on local coding practice, the specific wording of physician documentation, and coder-physician communication. To standardize the coding of postoperative respiratory failure, the 518.81 and 518.5 codes have recently been revised to make the available options clearer and mutually exclusive, which may improve the capacity of PSI 11 to discriminate true differences in quality of care.

Obstructive sleep apnea syndrome and perioperative complications: a systematic review of the literature

Obstructive sleep apnea syndrome (OSAS) is a common sleep related breathing disorder. Its prevalence is estimated to be between 2% and 25% in the general population. However, the prevalence of sleep apnea is much higher in patients undergoing elective surgery. Sedation and anesthesia have been shown to increase the upper airway collapsibility and therefore increasing the risk of having postoperative complications in these patients. Furthermore, the majority of patients with sleep apnea are undiagnosed and therefore are at risk during the perioperative period. It is important to identify these patients so that appropriate actions can be taken in a timely fashion. In this review article, we will discuss the epidemiology of sleep apnea in the surgical population. We will also discuss why these patients are at a higher risk of having postoperative complications, with the special emphasis on the role of anesthesia, opioids, sedation, and the phenomenon of REM sleep rebound. We will also review how to identify these patients preoperatively and the steps that can be taken for their perioperative management.

Development and validation of a risk calculator predicting postoperative respiratory failure

BACKGROUND

Postoperative respiratory failure (PRF) (requiring mechanical ventilation > 48 h after surgery or unplanned intubation within 30 days of surgery) is associated with significant morbidity and mortality. The objective of this study was to identify preoperative factors associated with an increased risk of PRF and subsequently develop and validate a risk calculator.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (NSQIP), a multicenter, prospective data set (2007-2008), was used. The 2007 data set (n = 211,410) served as the training set and the 2008 data set (n = 257,385) as the validation set.

RESULTS

In the training set, 6,531 patients (3.1%) developed PRF. Patients who developed PRF had a significantly higher 30-day mortality (25.62% vs 0.98%, P < .0001). On multivariate logistic regression analysis, five preoperative predictors of PRF were identified: type of surgery, emergency case, dependent functional status, preoperative sepsis, and higher American Society of Anesthesiologists (ASA) class. The risk model based on the training data set was subsequently validated on the validation data set. The model performance was very similar between the training and the validation data sets (c-statistic, 0.894 and 0.897, respectively). The high c-statistics (area under the receiver operating characteristic curve) indicate excellent predictive performance. The risk model was used to develop an interactive risk calculator.

CONCLUSIONS

Preoperative variables associated with increased risk of PRF include type of surgery, emergency case, dependent functional status, sepsis, and higher ASA class. The validated risk calculator provides a risk estimate of PRF and is anticipated to aid in surgical decision making and informed patient consent.

Noninvasive positive pressure ventilation for acute respiratory failure in children: a concise review

Noninvasive positive pressure ventilation (NPPV) refers to the delivery of mechanical respiratory support without the use of endotracheal intubation (ETI). The present review focused on the effectiveness of NPPV in children > 1 month of age with acute respiratory failure (ARF) due to different conditions. ARF is the most common cause of cardiac arrest in children. Therefore, prompt recognition and treatment of pediatric patients with pending respiratory failure can be lifesaving. Mechanical respiratory support is a critical intervention in many cases of ARF. In recent years, NPPV has been proposed as a valuable alternative to invasive mechanical ventilation (IMV) in this acute setting. Recent physiological studies have demonstrated beneficial effects of NPPV in children with ARF. Several pediatric clinical studies, the majority of which were noncontrolled or case series and of small size, have suggested the effectiveness of NPPV in the treatment of ARF due to acute airway (upper or lower) obstruction or certain primary parenchymal lung disease, and in specific circumstances, such as postoperative or postextubation ARF, immunocompromised patients with ARF, or as a means to facilitate extubation. NPPV was well tolerated with rare major complications and was associated with improved gas exchange, decreased work of breathing, and ETI avoidance in 22-100% of patients. High FiO₂ needs or high PaCO₂ level on admission or within the first hours after starting NPPV appeared to be the best independent predictive factors for the NPPV failure in children with ARF. However, many important issues, such as the identification of the patient, the right time for NPPV application, and the appropriate setting, are still lacking. Further randomized, controlled trials that address these issues in children with ARF are recommended.

Non-invasive ventilation in postoperative patients: a systematic review

BACKGROUND

Postoperative pulmonary complications, generally defined as any pulmonary abnormality occurring in the postoperative period, are still a significant issue in clinical practice increasing hospital length of stay, morbidity and mortality. Non-invasive ventilation (NIV), primarily applied in cardiogenic pulmonary edema, decompensated COPD and hypoxemic pulmonary failure, is nowadays also used in perioperative settings.

OBJECTIVE

Investigate the application and results of preventive and therapeutic NIV in postsurgical patients.

DESIGN

A systematic review.

DATA SOURCES

Medical literature databases were searched for articles about "clinical trials," "randomized controlled trials" and "meta-analyses." The keywords "cardiac surgery," "thoracic surgery," "lung surgery," "abdominal surgery," "solid organ transplantation," "thoraco-abdominal surgery" and "bariatric surgery" were combined with any of these: "non-invasive positive pressure ventilation," "continuous positive airway pressure," "bilevel ventilation," "postoperative complications," "postoperative care," "respiratory care," "acute respiratory failure," "acute lung injury" and "acute respiratory distress syndrome."

RESULTS

Twenty-nine articles (N=2,279 patients) met the inclusion criteria. Nine studies evaluated NIV in post-abdominal surgery, three in thoracic surgery, eight in cardiac surgery, three in thoraco-abdominal surgery, four in bariatric surgery and two in post solid organ transplantation used both for prophylactic and therapeutic purposes. NIV improved arterial blood gases in 15 of the 22 prophylactic and in 4 of the 7 therapeutic studies, respectively. NIV reduced the intubation rate in 11 of the 29 studies and improved outcome in only 1.

CONCLUSIONS

Despite these limited data and the necessity of new randomized trials, NIV could be considered as a prophylactic and therapeutic tool to improve gas exchange in postoperative patients.

Detection of postoperative respiratory failure: how predictive is the Agency for Healthcare Research and Quality's Patient Safety Indicator?

BACKGROUND

Patient Safety Indicator (PSI) 11, or postoperative respiratory failure, was developed by the US Agency for Healthcare Research and Quality to detect incident cases of respiratory failure after elective operations through use of ICD-9-CM diagnosis and procedure codes. We sought to determine the positive predictive value (PPV) of this indicator.

STUDY DESIGN

We conducted a retrospective cross-sectional study, sampling consecutive cases that met PSI 11 criteria from 18 geographically diverse academic medical centers on or before June 30, 2007. Trained abstractors from each center reviewed medical records using a standard instrument. We assessed the PPV of the indicator (with 95% CI adjusted for clustering within centers) and conducted descriptive analyses of the cases.

RESULTS

Of 609 cases that met PSI 11 criteria, 551 (90.5%; 95% CI, 86.5-94.4%) satisfied the technical criteria of the indicator and 507 (83.2%; 95% CI, 77.2-89.3%) represented true cases of postoperative respiratory failure from a clinical standpoint. The most frequent reasons for being falsely positive were nonelective hospitalization, prolonged intubation for airway protection, and insufficient evidence to support a diagnosis of acute respiratory failure. Fifty percent of true-positive cases involved substantial baseline comorbidities, and 23% resulted in death.

CONCLUSIONS

Although PSI 11 predicts true postoperative respiratory failure with relatively high frequency, the indicator does not limit detection to preventable cases. The PPV of PSI 11 might be increased by excluding cases with a principal diagnosis suggestive of a nonelective hospitalization and those with head or neck procedures. Removing the diagnosis code criterion from the indicator might also increase PPV, but would decrease the number of true positive cases detected by 20%.

Preoperative maneuvers to avert postoperative respiratory failure in elderly patients

BACKGROUND

The elderly appear particularly vulnerable to pulmonary complications following surgical procedures.

OBJECTIVE

The purpose of this study was to identify and assess the merit of various maneuvers employed to mitigate respiratory difficulties in elderly patients undergoing surgery.

RESULTS

The literature revealed evidence that diminishing sputum production with selective antibiotics and augmentation of sputum clearance with assisted coughing, postural drainage, and bronchodilators were deemed important. Futhermore, efforts to optimize nutritional status and eliminate tobacco and alcohol consumption are also felt to be of value in improving postsurgical outcome.

CONCLUSION

One significant aspect of this review was the apparent posity of recent work on this subject despite the profound magnitude of the demise related to postsurgical respiratory complications in elderly patients.

Hybrid Open-endovascular Repair for Thoracoabdominal Aortic Aneurysms: Current Status and Level of Evidence

PURPOSE

To report the results of a systematic review of the literature and to provide evidence for the hybrid open-endovascular repair (HOER) in patients with thoracoabdominal aortic aneurysms (TAAAs).

METHODS

A comprehensive literature review was performed and all studies identified that reported the results of HOER in patients with TAAA and information about primary technical and clinical success in evaluating the immediate and long-term complications such as neurological, renal and respiratory morbidity. All studies were reviewed by two independent observers for the above mentioned parameters.

RESULTS

After careful selection according to the given criteria, 13 studies were included in our statistical analysis. The number of reported patients totalled 58. Of those, 37 were men (64.4%) and the mean age of the patients was 68.1 years (range 35-80, 95%CI [72.8, 64.9]). All patients were unfit for open repair with severe comorbidities. The mean follow-up period was 14.5+/-8.7 months (range 4-36, 95%CI [18.7, 9.9]) and the mean aneurysm diameter was 7.15cm (range 5 to 12, 95%CI [7.87, 6.69]). 229 (97.8%) of the 234 visceral vessel grafts remained patent during the follow-up period. Reintervention was necessary in one (1.6%) of the five patients with an occluded graft. The overall long-term endoleak rate was 20.6% (12/58 patients) and the reintervention rate was 13.7% (8/58 patients). No patients developed procedure-related neurological deficits. The overall early and long-term mortality rate for completed procedures was 15.5% (9/58).

CONCLUSIONS

HOER shows promising mid-term results for high-risk patients who have TAAA, however, present evidence does not allow robust conclusions.

Pulmonary complications after descending thoracic and thoracoabdominal aortic aneurysm repair: predictors, prevention, and treatment

BACKGROUND

Although recent advances in surgical techniques have improved outcomes of descending thoracic (DTA) and thoracoabdominal aortic aneurysm (TAAA) repair, significant mortality and morbidity still occur. The aim of the current retrospective study is to determine predictors of postoperative pulmonary complications and prolonged hospital stay.

METHODS

Two hundred nineteen patients (median age, 66 years; range, 18 to 88; 112 male) underwent DTA (n = 79 [36%; 23 elephant trunk completions]) or TAAA (n = 140 [64%; Crawford I (52%), II (10%), III (11%), IV (7%); 31 elephant trunk completions]) between June 2002 and June 2005. Forty-one patients presented with ruptured aneurysms. Left atrial-to-femoral bypass was utilized in 51% of the patients. Femorofemoral bypass and distal aortic perfusion were used in 41% of the patients, deep hypothermic circulatory arrest (DHCA) was used in 43 patients (mean duration: 31 +/- 9 minutes); 8% were done with clamp-and-sew technique.

RESULTS

Adverse outcomes were seen in 21 patients (9.5%); hospital death in 13 (5.9%), and stroke in 13 (5 of whom died; 5.9%). Sixty patients (27%) experienced respiratory complications with prolonged postoperative ventilation (longer than 48 hours); 24 required tracheostomy (11%). Independent predictors of pulmonary complications after DTA/TAAA were TAAA (p = 0.03), preoperative blood urea nitrogen greater than 24 mg/dL (p = 0.03) and rupture (p = 0.09). The median hospital stay was 11 days (interquartile range, 6 to 35). Independent predictors of length of hospital stay were preoperative blood urea nitrogen (p = 0.045), postoperative bleeding (p < 0.005), reintubation (p = 0.001), tracheostomy (p < 0.0005), and transfusion of platelets (p = 0.008).

CONCLUSIONS

This contemporary experience demonstrates that preoperative renal insufficiency and extensive aneurysm are important predictors of respiratory complications after aortic aneurysm surgery.

What would Karl Landsteiner do? The ABO blood group and stem cell transplantation

ABO blood group antigens, of great importance in transplantation and transfusion, are present on virtually all cells, as well as in soluble form in plasma and body fluids. Naturally occurring plasma IgM and IgG antibodies against these antigens are ubiquitous. Nonetheless, the ABO blood group system is widely ignored by many transfusion services, except for purposes of red cell transfusion. We implemented a policy of transfusing only ABO identical platelets and red cells in patients undergoing stem cell transplantation or treatment for hematologic malignancies. Major bleeding episodes have occurred in about 5% of patients undergoing induction therapy for acute leukemia as compared with 15-20% in the literature. Overall survival times appear to be superior to that in historical cohorts. In 2002-2004, treatment-related mortality at 100 days in our Blood and Marrow Transplant Unit was 0.7% for autologous transplants (n=148), 13% for sibling allogeneic transplants (n=110), and 24% (n=62) for matched unrelated allogeneic transplants, suggesting that our approach is safe. We speculate that more rigorous efforts on the part of transfusion services to provide ABO identical blood components, and to remove incompatible supernatant plasma, when necessary, might yield reduced morbidity and mortality in patients undergoing stem cell transplantation.

Ten years experience of thoracic and thoracoabdominal aortic aneurysm surgical repair: lessons learned

In the last few years, advances in surgical techniques and in organ protection adjuncts have improved outcomes in thoracic (TAA) and thoracoabdominal aortic aneurysm (TAAA) surgical repair, although mortality and morbidity are still noteworthy. The aim of the current retrospective study is to determine whether the use of adjuncts influenced mortality and morbidity rates. From 1993 to 2003 we performed 353 procedures for TAA (175 cases) and TAAA (178 cases). This series has been divided into two consecutive groups: in group I (from 1993 to 1997), distal aortic perfusion with left atriofemoral bypass and cerebrospinal fluid drainage were used selectively, and in group II (from 1998 to 2003), the adjuncts were used routinely (together with surgical techniques of less invasive approach in selected cases). Total in-hospital mortality rates were significantly different ( p < 0.05): 15.9% in group I and 8.6% in group II. The overall incidence of paraplegia or paraparesis in group I was 8.3% and in Group II it was 5.1%. Renal failure occurred in 9.6% of group I and in 4.1% of group II. The incidence of respiratory failure in group I was 28%, and was 17.9% in group II. Respiratory failure was significantly lower ( p < 0.05) in group II. The reduction in the incidence of renal failure and paraplegia in the two groups was nonsignificant. In conclusion, the use of adjuncts and our improved experience allowed us to achieve a significant improvement in mortality and major morbidity rates in the group of patients operated on after 1998.

Pulmonary injury follows systemic inflammatory reaction in infrarenal aortic surgery

OBJECTIVE

To investigate whether an inflammatory response occurs in patients undergoing infrarenal aortic abdominal aneurysm repair, the localization and timing (ischemia and/or reperfusion) of this activation, and finally whether it affects postoperative pulmonary function.

DESIGN

Prospective, observational study.

SETTING

Academic referral center in Italy.

PATIENTS

We included 12 patients undergoing infrarenal aortic abdominal aneurysm repair and 12 patients undergoing major abdominal surgery.

INTERVENTIONS

Timed measurement of gene activation (angiotensinogen, angiotensin type 1 receptor, angiotensin-converting enzyme, and interleukin-6 genes) in muscle biopsies by reverse transcriptase-polymerase chain reaction (RT-PCR), and prospective assessment of interleukin-6 plasma concentration and pulmonary function (Pao2/FIO2 and Pao2/PAO2 ratios).

MEASUREMENTS AND MAIN RESULTS

After 30 mins of aortic clamping, angiotensinogen, angiotensin type 1 receptor, angiotensin-converting enzyme, and interleukin-6 genes were all overexpressed at RT-PCR studies in quadriceps muscle of patients undergoing aortic abdominal aneurysm repair, and the overexpression persisted after reperfusion. In situ hybridization and immunohistochemistry revealed that the inflammatory response was localized in endothelial cells. A significant increase in plasma interleukin-6 concentrations was then detectable at 6 and 12 hrs after reperfusion in aortic abdominal aneurysm surgery compared with patients undergoing abdominal surgery (p < .05). The increase in interleukin-6 plasma concentration was then followed (12 and 24 hrs after surgery) by a significant reduction of Pao2/ FIO2 and Pao2/PAO2 ratios (p < .05 vs. abdominal surgery).

CONCLUSIONS

The present study shows that a) during aortic surgery, the genes for interleukin-6 and for the components of the local renin-angiotensin system (angiotensinogen, angiotensin-converting enzyme, and angiotensin type 1 receptor subtype) are activated early in the ischemic muscle, and activation persists during reperfusion; b) interleukin-6 plasma concentration increases only in patients with tissue ischemia (aortic abdominal aneurysm), whereas no changes are detectable in patients with abdominal surgery; and finally c) the occurrence of systemic inflammatory reaction with increased interleukin-6 plasma concentrations is followed by impaired pulmonary function.

Predictors of Cardiac Morbidity And Mortality in Patients Undergoing Endovascular Repair of the Thoracic Aorta

The aim of this study was to determine predictors of cardiac morbidity and mortality in patients undergoing endovascular repair of the thoracic aorta. This was a retrospective cohort study that took place in a University-affiliated county hospital. Preoperative and intraoperative variables were collected from a consecutive series of patients who underwent repair of the thoracic aorta at our institution between 1998 and 2003. Perioperative complications and mortality were identified for each patient. Fifty-nine patients underwent endovascular repair of the thoracic aorta. The endografts were successfully deployed in 58 (98%) patients. Nine (15%) died perioperatively, 4 (7%) from cardiac causes. There were 12 (20%) perioperative cardiac events. A history of myocardial infarction (MI) was the only preoperative risk factor that was predictive of a cardiac event (p = 0.001). The cardiac event rate was 29% for patients who did not receive perioperative beta-blockade vs. 8% in patients who did (p = 0.04). Intraoperative predictors of MI were estimated blood loss (2480 cc vs. 680 cc, p = 0.01), intravenous (i.v.) fluids (2955 cc vs. 2010 cc, p =0.02), and length of operation (269 min vs. 178 min, p = 0.02). From these results we concluded that mortality associated with endovascular repair of thoracic aorta remains significant. Patients with a history of MI had a higher perioperative cardiac event rate. Intraoperative predictors of perioperative cardiac events included blood loss, i.v. fluid requirement, and length of operation. Perioperative beta-blockade is important in endovascular thoracic surgery as a protection against postoperative cardiac events.

Preoperative evaluation for postoperative pulmonary complications

Preoperative risk assessment for postoperative pulmonary complications is essential when counseling patients about the risks of surgery because of their significant associated morbidity and mortality. There are many patient-related, operation-related, and anesthesia-related risk factors for the development of PPCs. Though many of these risk factors are not modifiable, they can be useful in evaluating preoperative risk, especially when combined into formal risk indices. Preoperative risk assessment enables clinicians to target preoperative testing and perioperative risk reduction strategies to high-risk patients. Reducing PPC risk at the patient level will require a greater understanding of the impact of modifying risk factors through interventional trials. Reducing hospital PPC rates will require future research into the processes of care associated with PPCs through controlled observational and interventional trials.

Vocal cord paralysis after surgery for thoracic aortic aneurysm

OBJECTIVE

To determine the incidence, etiology, prognosis, and treatment of vocal cord paralysis (VCP) after surgery for thoracic aortic aneurysm (TAA).

STUDY DESIGN

Retrospective study performed between 1989 and 1995.

SETTING

Academic, tertiary care, referral medical center.

PATIENTS

Seventy-one TAA patients underwent surgery at the Kameda Medical Center between 1989 and 1995.

RESULTS

Sixty-two of 71 patients were examined postoperatively for voice quality. Twenty patients (32%) had hoarseness develop caused by VCP, as confirmed by laryngoscopy. The left recurrent laryngeal nerve had been sacrificed in 1 patient during surgery, but it was preserved in the remaining 19 patients. Unilateral left VCP was noted in 19 patients, and bilateral VCP occurred in 1 patient. The incidence of VCP was higher in those patients who underwent surgery for type I aneurysms (9 of 14 patients, 64%). In 16 of the 19 patients (84%) who received follow-up for > 6 months, vocal cord movement did not return to normal. Surgery to improve voice quality, arytenoid adduction in five patients and intracordal injection in two patients, was performed with success.

CONCLUSIONS

Our results indicate that surgery for TAA is associated with a relatively high incidence of VCP. VCP occurred despite preservation of the recurrent laryngeal nerve, and the paralysis did not show a spontaneous recovery even 6 months after surgery.

Functional outcome after thoracoabdominal aortic aneurysm repair

OBJECTIVE

Repair of thoracoabdominal aortic aneurysms (TAAAs) is performed for the improvement of long-term survival and the preservation of function. The determination of functional outcome and the identification of predictors of survival and functional recovery after TAAA repair are key to proper patient selection.

METHODS

This retrospective review of clinical data was performed in an academic medical center. The demographics, Crawford aneurysm type (I-18, II-33, III-22, IV-28), preoperative risk factors, operative characteristics, and postoperative complications and outcomes were recorded from the medical records for 101 consecutive patients who underwent TAAA repair (58 elective and 43 urgent/emergent). Functional status and living situation at hospital discharge and 12 months after discharge were determined from follow-up examination records or telephone contact with surviving patients. The patients then were categorized into "good" (survival, home, discharge to rehabilitation center, ambulatory) or "bad" (death, discharge to or residence in a long-term care facility, non-ambulatory) outcomes.

RESULTS

The postoperative mortality rate was 17.8% (10% in elective cases and 28% in urgent cases), and significant postoperative complications occurred in 77% of the cases (pulmonary complications in 41%, renal complications in 28%, and cord injury in 12%). The mean length of stay was 22.8 + 23.6 days, and at discharge, 80% of the patients were sent to home or rehabilitation and 20% were sent to long-term care facilities. At 1 year, 15 additional patients had died. All but two patients who had been initially discharged to rehabilitation had returned home, but only two patients who had been discharged to long-term care facilities had returned home and both were nonambulatory. Therefore, the survival rate at 1 year was 67%, and only 52.4% of the patients had a "good" outcome at 1 year (survival rate was 78% and rate of "good" outcome was 63% in patients who underwent elective TAAA repair). Independent predictors of postoperative death and "bad" outcome were age more than 75 years, preoperative heart disease, duration of visceral ischemia, use of left atrial femoral bypass graft, postoperative renal dysfunction, and number of organs failing after surgery.

CONCLUSION

Survival and good functional outcome after TAAA repair is significantly less common than expected and is primarily predicted with intraoperative factors and postoperative complications. Improved operative techniques and limitation of visceral ischemia reperfusion injury may improve outcome after TAAA repair.

[Postoperative lung complications and mortality in patients with mild-to-moderate COPD undergoing elective general surgery]

OBJECTIVE

To verify the incidence of postoperative pulmonary complications (PPC) and mortality inpatients with mild-to-moderate chronic obstructive pulmonary disease(COPD) who undergo elective general surgery. Incidence of PPC and mortality were studied in relation to sex, age, anesthesia,surgical incision, duration of surgery, smoking, respiratory symptoms, comorbidity, nutritional status, lung examination, abnormal electrocardiogram,and PaO2, PaCO2, FEV1 and FEV1/FVC.

DESIGN

Prospective, open study.

MATERIAL AND METHODS

Fifty-nine COPD patients were enrolled (FEV1/FVC< 88% of reference for women and < 89% for men) and studied at a tertiary care university hospital. The patients were examined during the pre-operative period and followed until discharge.

RESULTS

Twenty patients (33.9%) experienced PPC and 6 died, two (3.4%) from lung-related causes. Thirty-five PPC events occurred: pneumonia (37.2%), bronchospasm(22.9%), atelectasis (11.4%), acute respiratory insufficiency(11.4%), prolonged mechanical ventilation (11.4%) and bronchial infection (5.7%). Risk factors for PPC were male gender, duration of surgery over 270 minutes, low FEV1/FVC (71.9 +/-10.9%) and surgical incision in the chest or upper abdomen. No significant difference between patients with or without PPC were found for age, presence of respiratory symptoms, comorbidity,abnormal lung examination, nutritional status, smoking, abnormal electrocardiogram, PaO2, PaCO2, FEV1 or duration of pre-operative hospitalization. The rate of PPC was higher in patients smoking more than a mean 40 packs of cigarettes per year. Patients with PPC had longer hospital stays (16.6 +/-15.0 vs. 7.5 +/- 5.7 days) and stayed longer in intensive care units (7.0 +/- 5.9 vs. 1.7 +/- 0.7 days) than did those with no complications (p < 0.05).

CONCLUSIONS

The incidence of PPC was 33.9% and lung-related mortality was 3.4%. Risk factors were male gender, amount of smoking, duration of surgery over 270 minutes, low FEV1/FVC, and chest or upper abdominal incision. No risk factor was found to predict mortality in this group.

Perioperative Ventilation of the Vascular Surgery Patient

Although cardiovascular disease represents the most com mon comorbidity in patients undergoing vascular surgery, perioperative ventilatory issues can also play a vital role in achieving good outcomes. Postoperative respiratory failure is uncommon after carotid endarterectomy or peripheral revascularization procedures, the risk of pulmonary compli cations following intra-abdominal or intrathoracic vascular surgery is high. In addition to primary lung diseases such as chronic obstructive pulmonary disease, associated organ dysfunction syndromes such as stroke, renal failure, and congestive heart failure can also contribute to respiratory morbidity. An approach to minimizing respiratory complica tions begins with a careful preoperative search for ways to maximize pulmonary function and establishment of targets for postoperative weaning. Intraoperative attention should be paid to intraoperative management of bronchospasm, auto-positive end-expiratory pressure, and acid-base status. Postoperative management should strive for rapid extuba tion, continuation of pharmacologic conditioning programs begun preoperatively, and consideration of the use of post operative regional analgesia for patients with severe lung disease.

The relationship between visceral ischemia, proinflammatory cytokines, and organ injury in patients undergoing thoracoabdominal aortic aneurysm repair

OBJECTIVES

Plasma proinflammatory, anti-inflammatory cytokine, and soluble tumor necrosis factor (TNF) receptor concentrations were examined in hospitalized patients after abdominal and thoracoabdominal aortic aneurysm (TAAA) repair, with and without left atrial femoral bypass. Changes in plasma cytokine concentrations were related to the duration of visceral ischemia and the frequency rate of postoperative, single, or multiple system organ dysfunction (MSOD).

DESIGN

Prospective, observational study.

SETTING

Two academic referral centers in the United States and The Netherlands.

PATIENTS

We included 16 patients undergoing TAAA repair without left atrial femoral bypass, 12 patients undergoing TAAA repair with left atrial femoral bypass, and nine patients undergoing infrarenal aortic aneurysm repair.

MEASUREMENTS AND MAIN RESULTS

Timed, arterial blood sampling for proinflammatory and anti-inflammatory cytokine and soluble TNF receptor concentrations (p55 and p75), and prospective assessment of postoperative single and MSOD. Plasma appearance of TNF-alpha, interleukin (IL)-6, IL-8, and IL-10 peaked 1 to 4 hrs after TAAA repair, and concentrations were significantly elevated compared with infrarenal abdominal aortic aneurysm repair (p < .05). Left atrial femoral bypass significantly reduced the duration of visceral ischemia (p < .05) and the systemic TNF-alpha, p75, and IL-10 responses (p < .05). Plasma TNF-alpha concentrations >150 pg/mL were more common in patients with extended visceral ischemia times (>40 mins). Additionally, patients with early peak TNF-alpha concentrations >150 pg/mL and IL-6 levels >1,000 pg/mL developed MSOD more frequently than patients without these elevated plasma cytokine levels (both p < .05).

CONCLUSIONS

Thoracoabdominal aortic aneurysm repair results in the increased plasma appearance of TNF-alpha, IL-6, IL-8, IL-10, and shed TNF receptors. The frequency and magnitude of postoperative organ dysfunction after TAAA repair is associated with an increased concentration of the cytokines, TNF-alpha, and IL-6 and the increased plasma levels of these cytokines appear to require extended visceral ischemia times.

Multifactorial risk index for predicting postoperative respiratory failure in men after major noncardiac surgery. The National Veterans Administration Surgical Quality Improvement Program

OBJECTIVE

To develop and validate a preoperative risk index for predicting postoperative respiratory failure (PRF).

SUMMARY BACKGROUND DATA

Respiratory failure is an important postoperative complication.

METHOD

Based on a prospective cohort study, cases from 44 Veterans Affairs Medical Centers (n = 81,719) were used to develop the models. Cases from 132 Veterans Affairs Medical Centers (n = 99,390) were used as a validation sample. PRF was defined as mechanical ventilation for more than 48 hours after surgery or reintubation and mechanical ventilation after postoperative extubation. Ventilator-dependent, comatose, do not resuscitate, and female patients were excluded.

RESULTS

PRF developed in 2,746 patients (3.4%). The respiratory failure risk index was developed from a simplified logistic regression model and included abdominal aortic aneurysm repair, thoracic surgery, neurosurgery, upper abdominal surgery, peripheral vascular surgery, neck surgery, emergency surgery, albumin level less than 30 g/L, blood urea nitrogen level more than 30 mg/dL, dependent functional status, chronic obstructive pulmonary disease, and age.

CONCLUSIONS

The respiratory failure risk index is a validated model for identifying patients at risk for developing PRF and may be useful for guiding perioperative respiratory care.

Elective repair of type IV thoraco-abdominal aortic aneurysms; experience of a subcostal (transabdominal) approach

OBJECTIVE

preoperative pulmonary function has been shown by univariate analysis to be an independent predictor of outcome following Crawford Type IV thoraco-abdominal aortic aneurysm repair. The aim of this study was to determine if outcome had been improved by the introduction of a subcostal approach for the elective repair of these aneurysms.

METHODS

39 patients studied (19 subcostal, 20 thoracolaparotomy) all operated on between 1993 and 1998 by a single surgeon using a standard technique. No significant difference in median age (69 years) or weight (64 kg vs. 69 kg) between the two groups.

RESULTS

preoperative co-morbidities, pulmonary function and predictors of respiratory failure did not vary significantly between the two groups, despite a trend towards greater respiratory, cardiac and renal disease in the subcostal group. Preoperative median pulmonary function in both groups was 80% of that predicted for age, sex and height. The subcostal approach did not significantly reduce blood loss (3500 ml vs. 4500 ml) or anaesthetic time (255 min vs. 253 min). Overall 30 day mortality was 10.2%. The rate of re-operation was significantly higher in the subcostal group (21% vs. 0%, p=0.05). No differences were observed in intensive care unit stay, total hospital stay or respiratory complications, despite earlier extubation of the subcostal group (47% vs. 10% extubated at 12 h, p=0.01).

CONCLUSION

the introduction of a subcostal approach for type IV thoraco-abdominal aneurysm repair in selected "high risk" patients has been associated with an unacceptably high rate of complications requiring early re-operation. We feel that this relates to the problems inherent in the introduction of a new technique and reduced exposure in patients of inappropriate body habitus. The predicted benefit to pulmonary function is realised in shorter intubation times, but has not translated into earlier recovery or improved outcome. Operation duration and blood loss have not been significantly reduced. Based on these outcomes, we do not currently recommend the general adoption of this approach in all type IV repairs. We will continue to evaluate this approach in patients with poor pulmonary function and a suitable body habitus.

Successful surgical treatment of impending rupture of thoracoabdominal aortic aneurysm in an elderly patient with severe pulmonary emphysema

In a case of successful surgery for impending thoracoabdominal aortic aneurysmic rupture, an 83-year-old man with severe pulmonary emphysema was transferred to our hospital diagnosed with impending aneurysmic rupture. The aneurysm had been pointed out 2.5 years ago but surgical repair was not undertaken due to the patient's severe pulmonary emphysema. After admission, computed tomography showed an enlarging saccular thoracoabdominal aortic aneurysm. Emergency surgery was conducted because of severe pain below the left costal margin. We resected the wall of the saccular aortic aneurysm and reconstructed the aorta with an on-lay patch under femoro-femoral bypass and selective visceral organ perfusion. Tracheostomy provided respiratory care on the day following surgery. The patient was weaned from respiratory support 6 days after surgery. Postoperative aortography showed that the reconstructed thoracoabdominal aorta functioned satisfactorily. The patient remains in good health 18 months after surgery.

Endoluminal repair of aneurysms containing ostia of essential branch arteries: an experimental model

PURPOSE

To examine experimentally the feasibility of transfemoral endoluminal repair of aneurysms containing the ostia of essential branch arteries.

METHODS

In a canine model (n = 4), suprarenal aortic aneurysms were created by suturing an artificial patch onto an anterior arteriotomy. Following a 2-week recovery period, the dogs underwent endovascular exclusion of their aneurysms using an aortic stent-graft with separate renal artery branch grafts. Outcome was evaluated using angiography, intravascular ultrasound (IVUS), Doppler flow, invasive pressure monitoring, and autopsy, respectively.

RESULTS

Successful creation and subsequent endovascular exclusion of the aneurysm using aortic stent-grafts and separate bilateral renal artery stent-grafts was achieved in all trials. Angiographically, all aneurysms were excluded from aortic flow and all renal arteries were patent at completion of the procedure. With IVUS, good graft apposition and absence of perigraft flow were demonstrated in all animals. Mean pressure in the aneurysmal sac at completion of the procedure was 40 +/- 7 mmHg, compared to a mean systemic blood pressure of 105 +/- 8 mmHg (p < 0.05). At autopsy, no gross intimal damage was seen in the aorta or the renal arteries, and intact aortic grafts and branch grafts without twisting, coiling, or kinking were found in all trials.

CONCLUSIONS

In an acute animal model, suprarenal aortic aneurysms can be excluded from the circulation with preservation of renal flow using an endoluminally placed aortic stent-graft with separate branch grafts.

The impact of diaphragm management on prolonged ventilator support after thoracoabdominal aortic repair

PURPOSE

The relationship of the division of the diaphragm during thoracoabdominal aortic repair to prolonged ventilator support has not been studied. The purpose of this study was (1) to determine whether preservation of diaphragm integrity has a significant effect on postoperative ventilator duration and (2) to elucidate other pulmonary risk factors related to thoracoabdominal aortic surgery and to study the relationship of these factors to the intact diaphragm technique.

METHODS

Between February 1991 and January 1997, we repaired 397 descending and thoracoabdominal aortic aneurysms. Descending thoracic aneurysms were not included in the study because their repair does not include the diaphragm. A total of 256 patients participated in this study. The diaphragm was divided in 150 patients and left intact in 106 patients. Examined as potential risk factors were patient demographics, history and physical findings, aneurysm extent, urgency of the procedure, acute dissection, cross-clamp time, homologous and autologous blood product consumption, and adjunctive operative techniques. FEV1 also was considered in the 197 patients for whom preoperative spirometry was available. Prolonged mechanical ventilation was defined as ventilator support for >72 hours. Data were analyzed by univariate contingency table and multiple logistic regression methods.

RESULTS

Increasing age (odds ratio [OR], 1.02/y; P <.02), current smoking (OR, 2.6; P <.0008), total cross-clamp time (OR, 1.0/min; P <.008), units packed red blood cells transfused (OR, 1.06/unit; P <.008), and division of the diaphragm (OR, 2.03; P <.02) were significant, independent predictors of prolonged ventilation. Sixty-seven percent of patients (71 of 106) whose diaphragms were preserved were extubated in <72 hours compared with 52% of patients (78 of 150) who underwent diaphragm division (OR, 0.53; P <.02).

CONCLUSION

Independently of well known pulmonary risk factors, an intact diaphragm during thoracoabdominal aortic repair results in a higher probability of early ventilator weaning.

Clinical decision making and operative approaches to thoracic aortic aneurysms

The care of the patient with thoracic aneurysms is quite complicated. The decision to treat an aneurysm must be based on the risk of rupture and the patient's life expectancy. The preoperative evaluation must include detailed imaging to allow proper preoperative planning. This is especially important to determine the need for hypothermic circulatory arrest or the potential to treat a descending aneurysm with an endovascular approach. Thorough preoperative preparation and intraoperative care are as important as surgical decision making and meticulous technique. Although significant advances have been made in operative approaches, cerebral and myocardial preservation, and postoperative care, the management of complicated aneurysms of the thoracic aorta is frequently a humbling experience.