Prediction of postoperative pulmonary complications in a population-based surgical cohort. Anesthesiology. 2010;113:1338-1350. [PMID: 21045639 DOI: 10.1097/aln.0b013e3181fc6e0a]

The OPERA trial - comparison of early nasal high flow oxygen therapy with standard care for prevention of postoperative hypoxemia after abdominal surgery: study protocol for a multicenter randomized controlled trial

BACKGROUND

Respiratory support following postoperative extubation is of major importance to prevent hypoxemia and subsequent respiratory failure and reintubation. High-flow nasal cannula oxygen (HFNC) delivers a flow-dependent positive airway pressure and improves oxygenation by increasing end-expiratory lung volume. Whether application of HFNC may have therapeutic advantages over conventional oxygen therapy for respiratory support in the early postextubation surgical period remains to be established.

METHODS/DESIGN

The Optiflow for prevention of post-extubation hypoxemia after abdominal surgery (OPERA) trial is an investigator-initiated multicenter randomized controlled two-arm trial with assessor-blinded outcome assessment, randomizing 220 patients with intermediate to high risk of pulmonary complications after abdominal surgery to receive HFNC or conventional oxygen therapy following extubation, stratified by the presence of epidural analgesia and center. The primary outcome measure is the percentage of patients with postoperative hypoxemia one hour after tracheal extubation. Secondary outcome measures are postoperative pulmonary complications, need for noninvasive ventilation and intubation for respiratory failure.

DISCUSSION

The OPERA trial is the first randomized controlled study powered to investigate whether early application of HFNC following extubation after abdominal surgery prevents against postoperative hypoxemia and pulmonary complications.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01887015.

Risk factors and mortality after elective and emergent laparatomies for oncological procedures in 899 patients in the intensive care unit: a retrospective observational cohort study

Background

Abdominal surgeries for cancer are associated with postoperative complications and mortality. A view of the success of anaesthetic, surgical and critical care can be gained by analyzing factors associated with mortality in patients admitted to intensive care units (ICUs). The objective of this study was to identify the postoperative mortality rate and the causes of perioperative death in high-risk patients after abdominal surgery for cancer. A secondary objective was to explore possible risk factors for death in scheduled and emergency surgeries, with a view to finding guidance on preventable risk factors.

Methods

An observational study, in a 12-bed surgical ICU of a tertiary hospital. Patients admitted after abdominal surgery for cancer to the ICU for more than 24 hours’ care were included from January 1, 2008–December 31, 2009. Data were extracted from the minimum basic dataset. The main outcome considered was 90-day mortality.

Results

Of 899 patients included, 80 (8.9%) died. Seven died within 48 hours of surgery, 18 died between 2 and 7 days, and 55 died after 7 days. Non-survivors were older and had more respiratory comorbidity, chronic liver disease, metastasis, and underwent more palliative procedures. 112 patients underwent emergency surgery; mortality in these patients for resection surgery was 32.5%; in the 787 patients who underwent scheduled surgery, mortality was 4.7% for resection procedures. The estimated odds ratios (95% confidence interval) of preoperative patient factors in emergency surgery confirmed a negative association between survival and older age 0.96 (0.91–1), the presence of respiratory comorbidity 0.14 (0.02–0.77) and metastasis 0.18 (0.05–0.6). After scheduled surgery, survival was negatively associated with age 0.93 (0.90–0.96) and chronic liver disease 0.40 (0.17–0.91). Analysis of complications after emergency surgery also indicated a negative association with sepsis 0.03 (0.003–0.32), respiratory events 0.043 (0.011–0.17) and cardiac events 0.11 (0.027–0.45); after scheduled surgery, respiratory 0.03 (0.01–0.08) and cardiac 0.11 (0.02–0.45) events, renal failure 0.02 (0.006–0.14) and neurological events 0.06 (0.007–0.5).

Conclusions

As most deaths occurred after discharge from the ICU, postoperative sepsis, respiratory and cardiac events should be watched carefully on the ward.

Predicting postoperative pulmonary complications in the general population

PURPOSE OF REVIEW

Postoperative pulmonary complications (PPCs) are common and lead to longer hospital stays and higher mortality. A wide range of patient, anaesthetic and surgical factors have been associated with risk for PPCs. This review discusses our present understanding of PPC risk factors that can be used to plan preoperative risk reduction strategies. The methodological and statistical basis for building risk scores is also described.

RECENT FINDINGS

Studies in specific surgical populations or large patient samples have identified a range of predictors of PPC risk. Factors such as age, types of comorbidity and surgical characteristics have been found to be relevant in most of these studies. Recently, researchers have begun to develop risk scoring systems for a PPC composite outcome or for specific PPCs, especially pneumonia and respiratory failure. Preoperative arterial oxyhaemoglobin saturation is an objective measure that is easy to record and discriminates level of risk for impaired cardiorespiratory function. Preoperative anaemia and recent respiratory infection are factors that have lately been found to confer risk for PPCs.

SUMMARY

PPC risk prediction scales based on large population studies are being developed. New studies to confirm the validity of these scales in different geographic areas will be needed before we can be sure of their generalizability.

Nonventilatory strategies to prevent postoperative pulmonary complications

PURPOSE OF REVIEW

In this review, we aimed at providing the most recent and relevant clinical evidence regarding the use of nonventilatory strategies to prevent postoperative pulmonary complications (PPCs) after noncardiac surgery.

RECENT FINDINGS

Although nonavoidable, most comorbidities can be modified in order to reduce the incidence of pulmonary events postoperatively. The physical status of patients suffering from chronic obstructive pulmonary disease, asthma, obstructive sleep apnea, and congestive heart failure can be improved preoperatively, and a number of measures can be undertaken to prevent PPCs, including physiotherapy for pulmonary rehabilitation and drug therapies. Also, smokers may benefit from both short and long-term smoke cessation. Furthermore, the risk of PPCs may be reduced upon: choice of an adequate anesthesia strategy (e.g. regional vs. general); appropriate neuromuscular blockade and reversal; use of volatile instead of intravenous anesthetics in lung surgery; judicious intravascular volume expansion (restrictive vs. liberal strategy); regional instead of systemic analgesia after major surgery in high-risk patients; more strict indication for nasogastric decompression in order to avoid silent aspiration; and laparoscopic instead of open bariatric surgery.

SUMMARY

Nonventilatory strategies can play an important role in reducing PPCs and improving clinical outcome after noncardiac surgery, especially in high-risk patients.

Intraoperative ventilatory strategies to prevent postoperative pulmonary complications: a meta-analysis

PURPOSE OF REVIEW

It is uncertain whether patients undergoing short-lasting mechanical ventilation for surgery benefit from lung-protective intraoperative ventilatory settings including the use of lower tidal volumes, higher levels of positive end-expiratory pressure (PEEP) and/or recruitment maneuvers. We meta-analyzed trials testing the effect of lung-protective intraoperative ventilatory settings on the incidence of postoperative pulmonary complications.

RECENT FINDINGS

Eight articles (1669 patients) were included. Meta-analysis showed a decrease in lung injury development [risk ratio (RR) 0.40; 95% confidence interval (CI) 0.22-0.70; I 0%; number needed to treat (NNT) 37], pulmonary infection (RR 0.64; 95% CI 0.43-0.97; I 0%; NNT 27) and atelectasis (RR 0.67; 95% CI 0.47-0.96; I 48%; NNT 31) in patients receiving intraoperative mechanical ventilation with lower tidal volumes. Meta-analysis also showed a decrease in lung injury development (RR 0.29; 95% CI 0.14-0.60; I 0%; NNT 29), pulmonary infection (RR 0.62; 95% CI 0.40-0.96; I 15%; NNT 33) and atelectasis (RR 0.61; 95% CI 0.41-0.91; I 0%; NNT 29) in patients ventilated with higher levels of PEEP, with or without recruitment maneuvers.

SUMMARY

Lung-protective intraoperative ventilatory settings have the potential to protect against postoperative pulmonary complications.

Noninvasive respiratory support in the perioperative period

PURPOSE OF REVIEW

Pulmonary complications ranging from atelectasis to acute respiratory failure are common causes of poor perioperative outcomes. As the surgical population becomes increasingly at risk for pulmonary dysfunction due to increasing age and weight, development of an approach toward respiratory compromise in these patients is becoming ever more important. Given the utility of noninvasive respiratory support (NRS) in acute respiratory failure, it is likewise likely to also be important in the perioperative period.

RECENT FINDINGS

NRS is evaluated from preoperative risk assessment to its use in prevention and treatment of acute respiratory failure. Data supporting intraoperative use of NRS including preinduction continuous positive airway pressure and postextubation NRS for high-risk individuals and surgeries are examined. Timing and duration of NRS is also addressed. Finally, NRS is proposed for treatment for postoperative acute respiratory failure as an alternative to invasive rescue maneuvers.

SUMMARY

Noninvasive respiratory support should be considered an important adjunct in perioperative pulmonary care. Usage should be individually tailored in regard to timing and application modality specific to patient and surgical circumstances. More studies are needed, however, to determine the relationship demonstrated between short-term improvements in lung function and long-term outcomes.

Assessment of intraoperative microaspiration: does a modified cuff shape improve sealing?

BACKGROUND

Intra-operative aspiration of oropharyngeal secretions is associated with post-operative pneumonia. The use of endotracheal tubes (ETTs) with a modified cuff shape could be one preventive action. In this clinical, prospective, randomised controlled trial, we hypothesised that altering the cuff shape to a tapered shape could reduce the aspiration incidence. The primary outcome was aspiration of dye solution into the trachea.

METHODS

Patients scheduled for lumbar surgery were intubated with either an ETT with a barrel-shaped polyvinylchloride cuff (control group, n = 30) or tapered-shaped polyvinylchloride cuff (intervention group, n = 30). Subsequently, instillation with methylthioninium chloride was performed. At 10, 30, 60, 90, and 120 min after intubation, bronchoscopy was performed assessing the degree of dye descent along the cuff and digitally stored. Single blind review of the videoclips provided data on incidence of dye aspiration and depth of penetration along the cuff.

RESULTS

The traditional cuff showed descent of dye into the trachea in 20% of the patients. Although a tapered-shaped polyvinylchloride cuff leaked up to the second third of the cuff, no dye leakage into the trachea was observed. The use of a tapered-shaped cuff had a protective role against aspiration (T30: OR 3.0, CI 1.57-5.75; P = 0.001).

CONCLUSIONS

Short-term use of tapered-shaped polyvinylchloride cuffs in surgical patients results in more effective sealing of the tracheal lumen in comparison with a traditional barrel-shaped polyvinylchloride cuffs. Further evaluation is needed to determine whether a reduction in post-operative pneumonia can be demonstrated when these cuffs are used.

Is routine preoperative spirometry necessary in elderly patients undergoing laparoscopy-assisted gastrectomy?

Objectives

To identify predictors of postoperative pulmonary complications (PPCs) in patients aged ≥60 years who underwent laparoscopy-assisted gastrectomy (LAG), and to examine the value of preoperative spirometry to predict PPCs.

Methods

Patients with preoperative spirometric results who underwent LAG were retrospectively studied. Spirometry included four parameters: forced expiratory volume in 1 s; functional vital capacity; mean forced expiratory flow during middle of functional vital capacity; peak expiratory flow rate.

Results

Of 213 patients, overall incidence of PPCs was 19.2%. Abnormal spirometry findings were not identified as an independent predictor of PPCs using multivariate logistic regression analysis. Age was found to be the only independent predictor of PPCs out of all variables evaluated. Separate assessment of individual spirometric parameters using receiver-operating curve analyses indicated poor diagnostic accuracy.

Conclusions

Preoperative spirometry was not reliably predictive of PPCs, either as combined or individual parameters, in patients aged ≥60 years who underwent LAG. These results do not support routine use of spirometry to stratify risk of PPCs in this surgical population.

Update in perioperative medicine 2012

Perioperative medicine is an increasing area of research focus that brings together internists, anesthesiologists, surgeons, and hospitalists. A medical team approach to ensure the best possible patient outcomes has fostered collaborative strategies across areas of patient care. We review 8 seminal articles in the field of perioperative medicine. Each article was published in either 2011 or 2012 and adds to care strategies in the areas of perioperative cardiac medicine, pulmonary care, blood transfusion decision making, and medication management.

Postoperative pulmonary complications: reducing risks for noncardiac surgery

Postoperative pulmonary complications (PPCs) are a major contributor to the overall risk of noncardiac surgery that may lead to serious postoperative morbidity and long-term mortality. Nurse practitioners should be familiar with risk indices for PPCs, clinical guidelines, and risk reduction strategies to prevent PPCs and improve PPC outcomes.

N-acetylcysteine attenuates cardiopulmonary bypass-induced lung injury in dogs

Background

Cardiopulmonary bypass (CPB) is usually associated with inflammatory response that leads to various degrees of organ dysfunction in multiple systems, including lung injury. Our previous study showed that transforming growth factor beta1 (TGFβ1) was involved in CPB-induced lung injury. N-acetylcysteine (NAC) is an antioxidant and is able to prevent CPB-induced pneumocyte apoptosis through scavenging radical. Therefore, we investigated whether NAC may attenuate CPB-induced lung injury by inhibiting TGFβ1 expression.

Methods

Fifty-four 18 to 24-month-old mongrel dogs (15–16 kg) were randomly divided into control group, CPB group and NAC group (n = 18). Six dogs in each group were killed prior to, as well as 30 and 60 minutes after the operation (T0, T1 and T2). Lung injury was evaluated by hematoxylin and eosin (H&E) staining. Respiratory index (RI), oxygenation index (OI), malondialdehyde (MDA) content and superoxide dismutase (SOD) activity in the lung were determined at each time point. TGFβ1 expression was determined using real time RT-PCR and immunohistochemistry.

Results

A serious lung injury was observed after CPB in dogs. RI and MDA content were increased significantly after CPB, whereas OI and SOD activity were decreased. H&E staining showed that NAC treatment obviously attenuated CPB-induced lung injury. NAC treatment upregulated OI and SOD activity and downregulated RI and MDA content in the lung tissues of dogs after CPB. Treatment with NAC significantly suppressed the TGFβ1 expression in the lung tissues at both mRNA and protein levels.

Conclusion

Our results suggest that NAC is a potent agent against CPB-induced acute lung injury through inhibiting TGFβ1 expression.

Impact of operative duration on postoperative pulmonary complications in laparoscopic versus open colectomy

BACKGROUND

Prolonged operative duration is associated with increased postoperative morbidity and mortality. Although laparoscopic colectomy (LC) is associated with longer operative duration compared with open colectomy (OC), research shows paradoxically decreased morbidity following LC versus OC. The direct impact of operative duration on postoperative pulmonary complications (PPC) following LC versus OC has not been analyzed.

METHODS

We queried the ACS/NSQIP 2009-2010 Public Use File for patients who underwent elective LC and OC. The associations between operative duration and a PPC (pneumonia, intubation >48 h, and unplanned intubation) were evaluated. Multivariable regression models were created to determine the independent effect of operative time on the development of PPC controlling for LC versus OC.

RESULTS

A total of 25,419 colectomies (13,741 laparoscopic and 11,678 open) were reviewed; 765 (3 %) patients experienced at least one PPC. Regression modeling demonstrated that for both LC and OC each 60-min increase in operative time up to 480 min was associated with 13 % increased odds of PPC [odds ratio (OR) 1.13; 95 % confidence interval (CI) 1.07-1.19]. Beyond 480 min, each additional 60-min interval was associated with 33 % increased risk of PPC (OR 1.33; 95 % CI 1.12-1.58). Overall, PPCs occurred half as often following LC [270 (2 %) laparoscopic vs. 497 (4.3 %) open; OR 0.45; 95 % CI 0.39-0.53].

CONCLUSIONS

Operative duration is independently associated with increased risk of PPC in patients undergoing LC and OC. However, a laparoscopic approach carries half the absolute risk of PPC and, when safe, should be preferentially utilized despite a potential for prolonged operative duration.

[Do anesthetic techniques influence postoperative outcomes? Part I]

The influence of anesthetic technique on postoperative outcomes has opened a wide field of research in recent years. High-risk patients undergoing non-cardiac surgery are those who have higher incidence of postoperative complications and mortality. A proper definition of this group of patients should focus maximal efforts and resources to improve the results. In view of the significant reduction in postoperative mortality and morbidity in last 20 years, perioperative research should take into account new indicators to investigate the role of anesthetic techniques on postoperative outcomes. Studies focused on the evaluation of intermediate outcomes would probably discriminate better effectiveness differences between anesthetic techniques. We review some of the major controversies arising in the literature about the impact of anesthetic techniques on postoperative outcomes. We have grouped the impact of these techniques into 9 major investigation areas: mortality, cardiovascular complications, respiratory complications, postoperative cognitive dysfunction, chronic postoperative pain, cancer recurrence, postoperative nausea/vomiting, surgical outcomes and resources utilization. In this first part of the review, we discuss the basis on postoperative outcomes research, mortality, cardiovascular and respiratory complications.

Pulmonary complications after elective liver transplantation-incidence, risk factors, and outcome

After liver transplantation (LT), postoperative pulmonary complications (PPC) occur in approximately 35% to 50% of the recipients. Among these PPC, pneumonia is the most frequently encountered. Pulmonary dysfunction has also been widely reported among patients awaiting LT. The links between this dysfunction and PPC have not been clearly established. In this present cohort study, we evaluated the incidence and profile of post-LT pneumonia and identified potential preoperative risk factors.

METHODS

The postoperative clinical course of 212 liver transplant recipients between January 2008 and April 2010 was analyzed. These patients were treated in a single intensive care unit and received standardized postoperative care.

RESULTS

During the postoperative period, 47 (22%) patients developed pneumonia, of whom 20 (43%) developed respiratory failure requiring mechanical ventilation. Univariate analysis showed that several preoperative factors (age of recipient, model for end-stage liver disease score, indication for LT, platelet count, and restrictive lung pattern revealed by preoperative pulmonary function tests) and the transfusion (blood units and fresh frozen plasma units) during the operative period were associated with pneumonia. Using multivariate analysis by logistic regression, only a restrictive lung pattern (odds ratio=3.14; 95% confidence interval, 1.51-6.51; P=0.002) and the international normalized ratio measured prior LT (OR=4.95; 95% confidence interval, 1.86-8.59; P=0.0004) were independent predictors of pneumonia after LT.

CONCLUSION

Pneumonia is common among patients undergoing LT and is a major cause of morbidity. A restrictive pattern on preoperative pulmonary testing and a higher international normalized ratio measured prior LT were associated with more risk of postoperative pneumonia.

Mortality after surgery in Europe: a 7 day cohort study

BACKGROUND

Clinical outcomes after major surgery are poorly described at the national level. Evidence of heterogeneity between hospitals and health-care systems suggests potential to improve care for patients but this potential remains unconfirmed. The European Surgical Outcomes Study was an international study designed to assess outcomes after non-cardiac surgery in Europe.

METHODS

We did this 7 day cohort study between April 4 and April 11, 2011. We collected data describing consecutive patients aged 16 years and older undergoing inpatient non-cardiac surgery in 498 hospitals across 28 European nations. Patients were followed up for a maximum of 60 days. The primary endpoint was in-hospital mortality. Secondary outcome measures were duration of hospital stay and admission to critical care. We used χ(2) and Fisher's exact tests to compare categorical variables and the t test or the Mann-Whitney U test to compare continuous variables. Significance was set at p<0·05. We constructed multilevel logistic regression models to adjust for the differences in mortality rates between countries.

FINDINGS

We included 46,539 patients, of whom 1855 (4%) died before hospital discharge. 3599 (8%) patients were admitted to critical care after surgery with a median length of stay of 1·2 days (IQR 0·9-3·6). 1358 (73%) patients who died were not admitted to critical care at any stage after surgery. Crude mortality rates varied widely between countries (from 1·2% [95% CI 0·0-3·0] for Iceland to 21·5% [16·9-26·2] for Latvia). After adjustment for confounding variables, important differences remained between countries when compared with the UK, the country with the largest dataset (OR range from 0·44 [95% CI 0·19-1·05; p=0·06] for Finland to 6·92 [2·37-20·27; p=0·0004] for Poland).

INTERPRETATION

The mortality rate for patients undergoing inpatient non-cardiac surgery was higher than anticipated. Variations in mortality between countries suggest the need for national and international strategies to improve care for this group of patients.

FUNDING

European Society of Intensive Care Medicine, European Society of Anaesthesiology.

Influence of perioperative oxygen fraction on pulmonary function after abdominal surgery: a randomized controlled trial

Background

A high perioperative inspiratory oxygen fraction (FiO₂) may reduce the frequency of surgical site infection. Perioperative atelectasis is caused by absorption, compression and reduced function of surfactant. It is well accepted, that ventilation with 100% oxygen for only a few minutes is associated with significant formation of atelectasis. However, it is still not clear if a longer period of 80% oxygen results in more atelectasis compared to a low FiO₂.

Our aim was to assess if a high FiO₂ is associated with impaired oxygenation and decreased pulmonary functional residual capacity (FRC).

Methods

Thirty-five patients scheduled for laparotomy for ovarian cancer were randomized to receive either 30% oxygen (n = 15) or 80% oxygen (n = 20) during and for 2 h after surgery. The oxygenation index (PaO₂/FiO₂) was measured every 30 min during anesthesia and 90 min after extubation. FRC was measured the day before surgery and 2 h after extubation by a rebreathing method using the inert gas SF₆.

Results

Five min after intubation, the median PaO₂/FiO₂ was 69 kPa [53-71] in the 30%-group vs. 60 kPa [47-69] in the 80%-group (P = 0.25). At the end of anesthesia, the PaO₂/FiO₂ was 58 kPa [40-70] vs. 57 kPa [46-67] in the 30%- and 80%-group, respectively (P = 0.10). The median FRC was 1993 mL [1610-2240] vs. 1875 mL [1545-2048] at baseline and 1615 mL [1375-2318] vs. 1633 mL [1343-1948] postoperatively in the 30%- and 80%-group, respectively (P = 0.70).

Conclusion

We found no significant difference in oxygenation index or functional residual capacity between patients given 80% and 30% oxygen for a period of approximately 5 hours.

Trial registration

ClinicalTrials.gov Identifier: NCT00637936.

Oxygen and anesthesia: what lung do we deliver to the post-operative ward?

Anesthesia is safe in most patients. However, anesthetics reduce functional residual capacity (FRC) and promote airway closure. Oxygen is breathed during the induction of anesthesia, and increased concentration of oxygen (O(2) ) is given during the surgery to reduce the risk of hypoxemia. However, oxygen is rapidly adsorbed behind closed airways, causing lung collapse (atelectasis) and shunt. Atelectasis may be a locus for infection and may cause pneumonia. Measures to prevent atelectasis and possibly reduce post-operative pulmonary complications are based on moderate use of oxygen and preservation or restoration of FRC. Pre-oxygenation with 100% O(2) causes atelectasis and should be followed by a recruitment maneuver (inflation to an airway pressure of 40 cm H(2) O for 10 s and to higher airway pressures in patients with reduced abdominal compliance (obese and patients with abdominal disorders). Pre-oxygenation with 80% O(2) may be sufficient in most patients with no anticipated difficulty in managing the airway, but time to hypoxemia during apnea decreases from mean 7 to 5 min. An alternative, possibly challenging, procedure is induction of anesthesia with continuous positive airway pressure/positive end-expiratory pressure to prevent fall in FRC enabling use of 100% O(2) . A continuous PEEP of 7-10 cm H(2) O may not necessarily improve oxygenation but should keep the lung open until the end of anesthesia. Inspired oxygen concentration of 30-40%, or even less, should suffice if the lung is kept open. The goal of the anesthetic regime should be to deliver a patient with no atelectasis to the post-operative ward and to keep the lung open.

Bronchial asthma

PURPOSE OF REVIEW

The aim of this review is to underline the need for an adequate clinical and functional evaluation of respiratory function and asthma control in patients undergoing surgical procedures requiring general anesthesia to obtain useful information for an adequate preoperative pharmacological approach.

RECENT FINDINGS

It has been shown that baseline uncontrolled clinical/functional conditions of airways represent the most important risk factors for perioperative bronchospasm. In nonemergency conditions, asthma patients should undergo clinical/functional assessment at least 1 week before the surgery intervention to obtain, the better feasible control of asthma symptoms in the single patient. Some simple preoperative information given by the patient in preoperative consultation may be sufficient to identify individuals with uncontrolled or poor controlled asthmatic conditions. Spirometric evaluation is essential in individuals with poor control of symptoms, as well as in those patients with uncertain anamnestic data or limited perception of respiratory symptoms, and in those requiring lung resection.

SUMMARY

A better control of asthma must be considered the 'gold standard' for a patient at 'a reasonable low risk' to develop perioperative/postoperative bronchospasm. International consensus promoted by pulmonologists, anesthesiologists, and allergists might be useful to define a better diagnostic and therapeutic approach.

Pulmonary complications after major head and neck surgery: A retrospective cohort study

OBJECTIVES/HYPOTHESIS

Postoperative pulmonary complications (PPCs) following head and neck surgery are common. Patients undergoing tracheostomy, free tissue transfer reconstruction, and postoperative ventilation in an intensive care unit (ICU) have a high incidence of PPCs. We sought to define the incidence of PPCs in this cohort and to determine what factors PPCs correlate with.

STUDY DESIGN

Retrospective cohort study.

METHODS

Following institutional research ethics board approval, a retrospective review of patients undergoing major head and neck surgery at a Canadian tertiary care center was conducted. The development of PPCs was the outcome of interest. Quality assurance parameters including ICU and hospital lengths of stay, and mortality were also recorded.

RESULTS

There were 105 patients enrolled, of which 47 (44.8%) sustained one or more PPCs. The most frequent PPC was respiratory failure, accounting for 39 of 94 PPCs observed. Hypertension was the only comorbidity that correlated with development of a PPC (P = .031). Those who sustained PPCs were older than those who did not (median age, 65.6 vs. 58.7 years; P = .005). Development of PPCs correlated with longer ICU and hospital stays. There was increased mortality among patients with PPCs compared to those without (12.8% vs. 1.7%, P = .04).

CONCLUSIONS

Patients undergoing major head and neck surgery are at high risk of PPCs. Advanced age and hypertension significantly correlated with PPCs. PPCs correlate with prolonged ICU and hospital stays, and increased mortality. Further research is needed to define risk factors, useful investigations, and effective optimization strategies to mitigate PPCs.

[Risk factors for postoperative acute kidney injury in a cohort of 2378 patients from 59 hospitals]

OBJECTIVES

To assess risk factors for postoperative acute kidney injury (AKI) in adults with normal renal function hospitalized for major surgery. To analyze mortality and length of hospital stay in patients who develop postoperative AKI.

PATIENTS AND METHODS

Data for analysis were drawn from the 2006 ARISCAT study. The dependent variable was postoperative AKI defined as a decline in renal function demonstrated by a rise in plasma creatinine level to twice the baseline measurement or a 50% reduction in the glomerular filtration rate. Bivariate and multivariate analyses were used to identify preoperative and intraoperative risk factors.

RESULTS

We analyzed 2378 of the ARISCAT cases, which had been enrolled from 59 participating hospitals; 25 patients (1.1%) developed AKI. Analysis identified 5 risk factors: age, peripheral arterial disease, type of surgical incision, blood loss, and infusion of colloids. The area under the receiver operating characteristic curve was 0.88% (95% confidence interval, 0.79%-0.69%). Duration of hospital stay was longer for patients with postoperative AKI (21.8 days, vs 5.5 days for other patients; P=.007). Mortality was higher in patients with AKI at 30 days (36% vs 0.9%) and at 3 months (48% vs 1.7%).

CONCLUSIONS

The incidence of postoperative AKI was slightly over 1%. Knowledge of postoperative AKI risk factors can facilitate the planning of surgical interventions and anesthesia to reduce subsequent morbidity and mortality and length of hospital stay.

Developing performance measures for patient blood management

In 2005, The Joint Commission set about assessing the need for performance measures associated with the provision of blood products. Through a rigorous process, seven patient blood management performance measures were created. These measures incorporated a measure requiring transfusion consent; three measures requiring the combination of a laboratory value and a rationale for transfusion of plasma, platelets, or red blood cells; a measure requiring standard documentation about a transfusion; a measure evaluating preoperative anemia screening; and a measure of preoperative type screening and antibody testing before the start of major blood loss surgery. This article describes the process of this measure development and summarizes the final measures and some of the evidence supporting the measures.

Perioperative pulmonary complications

PURPOSE OF REVIEW

This article reviews current concepts in perioperative pulmonary management.

RECENT FINDINGS

Preoperative risk assessment tools for perioperative pulmonary complications (POPCs) are evolving for both children and adults. Intraoperative management strategies have a demonstrable effect on outcomes. Late POPCs may be preceded by clinical signs.

SUMMARY

POPCs are common and lead to significant resource utilization. Optimal POPC risk mitigation must span all phases of surgical care. Preoperative assessment may identify patients at risk and effectively lower their risk by identifying targeted interventions. Intra-operative strategies impact postoperative outcome. POPCs continue to be a concern for several days postoperatively. We review the current literature on this broad subject with a focus on implementable interventions for the clinician.

Rationale and study design of PROVHILO - a worldwide multicenter randomized controlled trial on protective ventilation during general anesthesia for open abdominal surgery

BACKGROUND

Post-operative pulmonary complications add to the morbidity and mortality of surgical patients, in particular after general anesthesia >2 hours for abdominal surgery. Whether a protective mechanical ventilation strategy with higher levels of positive end-expiratory pressure (PEEP) and repeated recruitment maneuvers; the "open lung strategy", protects against post-operative pulmonary complications is uncertain. The present study aims at comparing a protective mechanical ventilation strategy with a conventional mechanical ventilation strategy during general anesthesia for abdominal non-laparoscopic surgery.

METHODS

The PROtective Ventilation using HIgh versus LOw positive end-expiratory pressure ("PROVHILO") trial is a worldwide investigator-initiated multicenter randomized controlled two-arm study. Nine hundred patients scheduled for non-laparoscopic abdominal surgery at high or intermediate risk for post-operative pulmonary complications are randomized to mechanical ventilation with the level of PEEP at 12 cmH(2)O with recruitment maneuvers (the lung-protective strategy) or mechanical ventilation with the level of PEEP at maximum 2 cmH(2)O without recruitment maneuvers (the conventional strategy). The primary endpoint is any post-operative pulmonary complication.

DISCUSSION

The PROVHILO trial is the first randomized controlled trial powered to investigate whether an open lung mechanical ventilation strategy in short-term mechanical ventilation prevents against postoperative pulmonary complications.

TRIAL REGISTRATION

ISRCTN: ISRCTN70332574.

Molecular mechanisms in male determination and germ cell differentiation

Sex determination and gametogenesis are key processes in human reproduction, and any defect can lead to infertility. We describe here the molecular mechanisms of male sex determination and testis formation; defects in sex determination lead to a female phenotype despite the presence of a Y chromosome, more rarely to a male phenotype with XX chromosomes, or to intersex phenotypes. Interestingly, these phenotypes are often associated with other developmental malformations. In testis, spermatozoa are produced from renewable stem cells in a complex differentiation process called spermatogenesis. Gene expression during spermatogenesis differs to a surprising degree from gene expression in somatic cells, and we discuss here mechanistic differences and their effect on the differentiation process and male fertility.