Mechanisms of pulmonary dysfunction after on-pump and off-pump cardiac surgery: a prospective cohort study

The mitochondrial-derived peptide MOTS-c suppresses ferroptosis and alleviates acute lung injury induced by myocardial ischemia reperfusion via PPARγ signaling pathway

Acute lung injury (ALI) is a life-threatening complication of cardiac surgery that has a high rate of morbidity and mortality. Epithelial ferroptosis is believed to be involved in the pathogenesis of ALI. MOTS-c has been reported to play a role in regulating inflammation and sepsis-associated ALI. The purpose of this study is to observe the effect of MOTS-c on myocardial ischemia reperfusion (MIR)-induced ALI and ferroptosis. In humans, we used ELISA kits to investigate MOTS-c and malondialdehyde (MDA) levels in patients undergoing off-pump coronary artery bypass grafting (CABG). In vivo, we pretreated Sprague-Dawley rats with MOTS-c, Ferrostatin-1 and Fe-citrate(Ⅲ). We conducted Hematoxylin and Eosin (H&E) staining and detection of ferroptosis-related genes in MIR-induced ALI rats. In vitro, we evaluated the effect of MOTS-c on hypoxia regeneration (HR)-induced mouse lung epithelial-12 (MLE-12) ferroptosis and analyzed the expression of PPARγ through western blotting. We found that circulating MOTS-c levels were decreased in postoperative ALI patients after off-pump CABG, and that ferroptosis contributed to ALI induced by MIR in rats. MOTS-c suppressed ferroptosis and alleviated ALI induced by MIR, and the protective effect of MOTS-c- was dependent on PPARγ signaling pathway. Additionally, HR promoted ferroptosis in MLE-12 cells, and MOTS-c inhibited ferroptosis against HR through the PPARγ signaling pathway. These findings highlight the therapeutic potential of MOTS-c for improving postoperative ALI induced by cardiac surgery.

Impact of Non-cardiac Comorbidities in Adults with Congenital Heart Disease: Management of Multisystem Complications

The prevalence and impact of non-cardiac comorbidities in adult patients with congenital heart disease increase over time, and these complications are often specifically a consequence of the long-term altered cardiovascular physiology or sequelae of previous therapies. For the ACHD patient admitted to the intensive care unit (ICU) for either surgical or medical treatment, an assessment of the burden of multisystem disease, as well as an understanding of the underlying cardiovascular pathophysiology, is essential for optimal management of these complex patients. This chapter takes an organ-system-based approach to reviewing common comorbidities in the ACHD patient, focusing on conditions that are directly related to ACHD status and may significantly impact ICU care.

Financial Impact of Incentive Spirometry

Despite largely unproven clinical effectiveness, incentive spirometry (IS) is widely used in an effort to reduce postoperative pulmonary complications. The objective of the study is to evaluate the financial impact of implementing IS. The amount of time nurses and RTs spend each day doing IS-related activities was assessed utilizing an online survey distributed to the relevant national nursing and respiratory therapists (RT) societies along with questionnaire that was prospectively collected every day for 4 weeks at a single 10-bed cardiothoracic surgery step-down unit. Cost of RT time to teach IS use to patients and cost of nurse time spent reeducating and reminding patients to use IS were used to calculate IS implementation cost estimates per patient. Per-patient cost of IS implementation ranged from $65.30 to $240.96 for a mean 9-day step-down stay. For the 566 patients who stayed in the 10-bed step-down in 2016, the total estimated cost of implementing IS ranged from $36 959.80 to $136 383.36. Using national survey workload data, per-patient cost of IS implementation costed $107.36 (95% confidence interval [CI], $97.88-$116.98) for a hospital stay of 4.5 days. For the 9.7 million inpatient surgeries performed annually in the United States, the total annual cost of implementing postoperative IS is estimated to be $1.04 billion (95% CI, $949.4 million-$1.13 billion). The cost of implementing IS is substantial. Further efficacy studies are necessary to determine whether the cost is justifiable.

Physiotherapy mobility and walking management of uncomplicated coronary artery bypass graft (CABG) surgery patients: a survey of clinicians' perspectives in Australia and New Zealand

Background: This study aimed to determine current mobility and walking management by physiotherapists of patients undergoing coronary artery bypass graft (CABG) surgery, the clinical milestones expected and physiotherapists' perception of the severity of pain experienced by patients after surgery. Design: Cross sectional study using a questionnaire. Methods: All hospitals in Australia and New Zealand that perform cardiac surgery (n = 54) were invited to complete a questionnaire. Findings: Forty-one questionnaires were returned and analysed (response rate 76%). Walking distance was a clinical milestone after CABG surgery. Walking and transferring patients from bed to chair required the most time of physiotherapists during one treatment session. Physiotherapists perceived that patients experienced most pain on day one after surgery [mean (SD)] visual analogue scale (VAS) 41 (16) mm and this reduced by day four to VAS 15 (10) mm. Patients' pain was perceived to be significantly higher after physiotherapy sessions compared with before (p < 0.01). Thirty-seven respondents (90%) believed that patients' pain was well managed for physiotherapy treatments. A majority of the respondents (68%) believed that pain was not a limiting factor in the distance patients walked in a physiotherapy session and most (90%) believed that general fatigue limited walk distance. Conclusion: This research provides current mobility and walking management by physiotherapists of patients undergoing CABG surgery in Australia and New Zealand.

Extended donor criteria in heart transplantation: a retrospective study from a single Chinese institution

Background

Heart donor selection criteria have been progressively widened due to increasing donor recipient mismatch. This study evaluates the outcomes of the use marginal donor hearts for orthotopic heart transplantation (OHT) based on a single center experience in China.

Methods

We retrospectively analyzed outcomes of patients undergoing OHT in our hospital between September 2008 and December 2015. All the donor hearts were from voluntary donation of brain-dead patients. The primary outcome was overall survival; secondary outcomes included cardiopulmonary bypass (CPB) time, ventilation time, post-operative mechanical support and medium-term complications.

Results

Overall, 278 patients with OHT were analyzed. Whereas 180 patients (64.7%) underwent OHT utilizing marginal donors (MD group), only 98 patients (35.3%) underwent OHT with standard donors (SD group). Compared to the SD group, the MD group had longer CPB time (P=0.001), ventilation time (P=0.010) and increased mechanical support rate (P=0.011). Survival rates were comparable between the two groups at 30 days, 1 year, 3 years and 5 years (92.2%, 83.3%, 70.6%, 70.6% vs. 95.9%, 91.4%, 80.2%, 80.2% respectively). Multivariate Cox regression analysis revealed that female recipient gender [hazard ratio (HR) =2.632 (1.325-5.227), P=0.006], diagnosis (P=0.014) and abnormal donor heart structure [HR =3.638 (1.005-13.167), P=0.049] were three predictors for 1-year all-cause mortality. The occurrence of complications in the recipients with more than 3-year follow-up did not differ between the two cohorts.

Conclusions

Marginal donor can be reasonably applied to expand the benefits of transplantation. Changing previous MD criteria to include donors with an age greater than 50 years, cold ischemic time less than 6 hours, donor/recipient weight ratio less than 0.8, compatible blood type, hepatitis virus seropositivity and MD used for male recipient will likely offer a good prognosis.

Analysis of the influence of respiratory disorders observed in preoperative spirometry on the dynamics of early inflammatory response in patients undergoing isolated coronary artery bypass grafting

Background

Preoperative spirometry provides measurable information about the occurrence of respiratory disorders. The aim of this study was to assess the association between preoperative spirometry abnormalities and the intensification of early inflammatory responses in patients following coronary artery bypass graft in extracorporeal circulation.

Material and methods

The study involved 810 patients (625 men and 185 women) aged 65.4±7.9 years who were awaiting isolated coronary artery bypass surgery. On the basis of spirometry performed on the day of admittance to the hospital, the patients were divided into three groups. Patients without respiratory problems constituted 78.8% of the entire group. Restricted breathing was revealed by spirometry in 14.9% and obstructive breathing in 6.3% of patients.

Results

Inter-group analysis showed statistically significant differences in C-reactive protein (CRP) between patients with restrictive spirometry abnormalities and patients without any pulmonary dysfunction. CRP concentrations differed before surgery (P=0.006) and on the second (P<0.001), fourth (P=0.005) and sixth days after surgery (P=0.029). There was a negative correlation between CRP levels and FEV₁.

Conclusion

In our study, the most common pulmonary disorders in the coronary artery bypass graft patients were restrictive. Patients with abnormal spirometry results from restrictive respiratory disorders have an elevated level of generalized inflammatory response both before and after the isolated coronary artery bypass surgery. Therefore, this group of patients should be given special postoperative monitoring and, in particular, intensive respiratory rehabilitation immediately after reconstitution.

Off-pump grafting does not reduce postoperative pulmonary dysfunction

Objectives Pulmonary dysfunction is a recognized postoperative complication that may be linked to use of cardiopulmonary bypass. The off-pump technique of coronary artery bypass aims to avoid some of the complications that may be related to cardiopulmonary bypass. In this study, we compared the influence of on-pump or off-pump coronary artery bypass on pulmonary gas exchange following routine surgery. Methods Fifty patients (mean age 60.4 ± 8.4 years) with no preexisting lung disease and good left ventricular function undergoing primary coronary artery bypass grafting were prospectively randomized to undergo surgery with or without cardiopulmonary bypass. Alveolar/arterial oxygen pressure gradients were calculated prior to induction of anesthesia while the patients were breathing room air, and repeated postoperatively during mechanical ventilation and after extubation while inspiring 3 specific fractions of oxygen. Results Baseline preoperative arterial blood gases and alveolar/arterial oxygen pressure gradients were similar in both groups. At both postoperative stages, the partial pressure of arterial oxygen and alveolar/arterial oxygen pressure gradients increased with increasing fraction of inspired oxygen, but there were no statistically significant differences between patients who underwent surgery with or without cardiopulmonary bypass, either during ventilation or after extubation. Conclusions Off-pump surgery is not associated with superior pulmonary gas exchange in the early postoperative period following routine coronary artery bypass grafting in patients with good left ventricular function and no preexisting lung disease.

Incidence and risk factors for aspiration pneumonia after cardiovascular surgery in elderly patients

OBJECTIVE

Pneumonia after cardiovascular surgery is the leading cause of mortality. Postoperative aspiration pneumonia becomes a critical issue in the management of cardiovascular surgery in the aging society. The aim of this study was to investigate the incidence and risk factors of aspiration pneumonia after cardiovascular surgery for elderly patients.

METHODS

This study consisted of 123 elderly patients (>65 years old) who survived their final extubation following cardiovascular surgery at Kinan Hospital. Patients were divided into aspiration pneumonia and no pneumonia groups. Postoperative aspiration pneumonia was diagnosed by two independent physicians according to the nursing- and healthcare-associated pneumonia guidelines by the Japanese Respiratory Society.

RESULTS

Among the patients, 12 (9.8 %) had aspiration pneumonia. There were no differences in patients' characteristics between the groups except for a history of cerebral vascular disorder (aspiration pneumonia 42 % vs no pneumonia 15 %, p = 0.04) and ejection fraction (EF) (aspiration pneumonia 56 ± 21 % vs no pneumonia 66 ± 13 %, p = 0.02). Only six (5 %) patients needed more than 12 h intubation. There was no difference in the operative factors between the groups. Neurological deficit was more frequently observed in the aspiration pneumonia group (33 vs 5 %, p = 0.005). Multivariable logistic regression analysis showed that the history of cerebral vascular disorder and neurological deficit after surgery was independent risk factors for aspiration pneumonia after cardiovascular surgery.

CONCLUSIONS

Our results could assist in screening elderly patients who should be more carefully evaluated before oral nutrition to minimize morbidity and mortality after cardiovascular surgery.

Addressing the Global Burden of Trauma in Major Surgery

Despite a technically perfect procedure, surgical stress can determine the success or failure of an operation. Surgical trauma is often referred to as the "neglected step-child" of global health in terms of patient numbers, mortality, morbidity, and costs. A staggering 234 million major surgeries are performed every year, and depending upon country and institution, up to 4% of patients will die before leaving hospital, up to 15% will have serious post-operative morbidity, and 5-15% will be readmitted within 30 days. These percentages equate to around 1000 deaths and 4000 major complications every hour, and it has been estimated that 50% may be preventable. New frontline drugs are urgently required to make major surgery safer for the patient and more predictable for the surgeon. We review the basic physiology of the stress response from neuroendocrine to genomic systems, and discuss the paucity of clinical data supporting the use of statins, beta-adrenergic blockers and calcium-channel blockers. Since cardiac-related complications are the most common, particularly in the elderly, a key strategy would be to improve ventricular-arterial coupling to safeguard the endothelium and maintain tissue oxygenation. Reduced O2 supply is associated with glycocalyx shedding, decreased endothelial barrier function, fluid leakage, inflammation, and coagulopathy. A healthy endothelium may prevent these "secondary hit" complications, including possibly immunosuppression. Thus, the four pillars of whole body resynchronization during surgical trauma, and targets for new therapies, are: (1) the CNS, (2) the heart, (3) arterial supply and venous return functions, and (4) the endothelium. This is termed the Central-Cardio-Vascular-Endothelium (CCVE) coupling hypothesis. Since similar sterile injury cascades exist in critical illness, accidental trauma, hemorrhage, cardiac arrest, infection and burns, new drugs that improve CCVE coupling may find wide utility in civilian and military medicine.

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

OBJECTIVES

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

DATA SOURCE AND SYNTHESIS

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

CONCLUSIONS

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

Postoperative pulmonary dysfunction and mechanical ventilation in cardiac surgery

Postoperative pulmonary dysfunction (PPD) is a frequent and significant complication after cardiac surgery. It contributes to morbidity and mortality and increases hospitalization stay and its associated costs. Its pathogenesis is not clear but it seems to be related to the development of a systemic inflammatory response with a subsequent pulmonary inflammation. Many factors have been described to contribute to this inflammatory response, including surgical procedure with sternotomy incision, effects of general anesthesia, topical cooling, and extracorporeal circulation (ECC) and mechanical ventilation (VM). Protective ventilation strategies can reduce the incidence of atelectasis (which still remains one of the principal causes of PDD) and pulmonary infections in surgical patients. In this way, the open lung approach (OLA), a protective ventilation strategy, has demonstrated attenuating the inflammatory response and improving gas exchange parameters and postoperative pulmonary functions with a better residual functional capacity (FRC) when compared with a conventional ventilatory strategy. Additionally, maintaining low frequency ventilation during ECC was shown to decrease the incidence of PDD after cardiac surgery, preserving lung function.

Lung preconditioning in anesthesia: Review of the literature

Lung injury can arise during or after anesthesia and can lead to a complicated postoperative course with great implications for the patient. Unfortunately, treatment of acute lung injury is at the moment mainly supportive and rates of recovery have not really improved in the recent years. In many cases, lung injury can be anticipated and preventive measures seem possible. This represents a unique challenge to the anesthesiologist, as some new opportunities to reduce the frequency and/or severity of lung injury seem now available. These chances may arise from the potency of preconditioning the lungs before the main injury, with smaller injurious insults. Although preconditioning began to be applicated first on the myocardium, experimental studies have shown potentially beneficial results also for the lungs. This review summarizes the main methods of lung preconditioning that have been tried in experimental studies in the literature and the main mechanisms that are perhaps involved. Emphasis is given in the two main methods of preconditioning that seem readily applicable in the clinical praxis, that is ischemic preconditioning, as well as preconditioning with volatile anesthetics. The few, but interesting clinical studies are also summarized and the future research points in this evolving field of anesthesia are stressed.

Pulmonary functions before and after pediatric cardiac surgery

This study aimed to assess pulmonary functions before and after cardiac surgery in infants with congenital heart diseases and pulmonary overflow and to clarify which echocardiographic parameter correlates best with lung mechanics. Between 2008 and 2009, 30 infants with left-to-right shunt congenital acyanotic heart diseases who had indications for reparative surgery of these lesions were assessed by echocardiography and infant pulmonary function tests before the operation and 6 months afterward. Tests using baby body plethysmography were performed to assess the following infant pulmonary functions: tidal volume, respiratory rate, respiratory system compliance (C(rs)) and respiratory system resistance, functional residual capacity (FRC), and airway resistance. The mean age of the patients was 10.47 ± 3.38 months, and their mean weight was 6.81 ± 1.67 kg. Ventricular septal defect and combined lesions were the predominant cardiac diseases (26.7%). Comparison of the infant pulmonary function tests showed a highly significant improvement in all the parameters between the preoperative and 6-month postoperative visits (p < 0.0001). Systolic pulmonary artery pressure had a statistically significant negative correlation with C(rs) (r = -0.493, p = 0.006) and a positive correlation with FRC (r = 0.450, p = 0.013). The findings showed that C(rs) had a statistically significant negative correlation with the pulmonary artery size (r = -0.398, p = 0.029) and the left atrium size (r = -0.395, p = 0.031), whereas the pulmonary artery size had a statistically positive correlation with effective resistance (r = 0.416, p = 0.022) and specific effective resistance (r = 0.604, p = 0.0001). Surgical correction of left-to-right shunt congenital heart diseases had a positive impact on lung compliance, airway resistance, and FRC. Noninvasive echocardiographic parameters assessing pulmonary vascular engorgement and pulmonary artery pressure were closely related to these infant pulmonary function test indexes.

The utility of lung epithelium specific biomarkers in cardiac surgery: a comparison of biomarker profiles in on- and off-pump coronary bypass surgery

Background

Despite continuous improvements in materials and perfusion techniques, cardiac surgery still causes lung injury and a delay of pulmonary recovery. Currently, there is no gold standard for quantifying cardiac surgery induced lung injury and dysfunction. Adding objective measures, such as plasma biomarkers, could be of great use here. In this study the utility of lung epithelium specific proteins as biomarkers for lung dysfunction was evaluated.

Methods

Serial measurements of plasma concentrations of Clara cell 16 kD (CC16) protein, Surfactant protein D (SP-D), Elastase and Myeloperoxidase were performed on blood samples from 40 patients who underwent coronary artery bypass grafting with cardiopulmonary bypass (CABG, n = 20) or without cardiopulmonary bypass (OPCAB, n = 20).

Results

The increase of SP-D and CC16 between pre-operative concentrations and concentrations at the end of cardiopulmonary bypass, correlated with the Aa-O₂ gradient at 1 hour on the ICU (R_s = 0.409, p = .016 and R_s = 0.343, p = .043, respectively).

Furthermore, SP-D and CC16 were higher in CABG than in OPCAB at the end of surgery [8.96 vs. 4.91 ng/mL, p = .042 and 92 vs. 113%, p = .007, respectively]. After 24 h both biomarkers returned to their baseline values.

Conclusions

Our results show that increases in plasma of SP-D and CC16 correlate with clinical lung injury after coronary artery bypass surgery. Therefore, lung epithelium specific proteins seem to be a useful biomarker for measuring lung injury in the setting of cardiac surgery.

Pulmonary pathophysiology and lung mechanics in anesthesiology: a case-based overview

Anesthesia, surgical requirements, and patients' unique pathophysiology all combine to make the accumulated knowledge of respiratory physiology and lung mechanics vital in patient management. This article take a case-based approach to discuss how the complex interactions between anesthesia, surgery, and patient disease affect patient care with respect to pulmonary pathophysiology and clinical decision making. Two disparate scenarios are examined: a patient with chronic obstructive pulmonary disease undergoing a lung resection, and a patient with coronary artery disease undergoing cardiopulmonary bypass. The impacts of important concepts in pulmonary physiology and respiratory mechanics on clinical management decisions are discussed.

Incentive spirometry for preventing pulmonary complications after coronary artery bypass graft

BACKGROUND

Incentive spirometry (IS) is a treatment technique that uses a mechanical device to reduce pulmonary complications during postoperative care. This is an update of a Cochrane review first published in 2007.

OBJECTIVES

Update the previously published systematic review to compare the effects of IS for preventing postoperative pulmonary complications in adults undergoing coronary artery bypass graft (CABG).

SEARCH METHODS

We searched CENTRAL and DARE on The Cochrane Library (Issue 2 of 4 2011), MEDLINE OVID (1948 to May 2011), EMBASE (1980 to Week 20 2011), LILACS (1982 to July 2011) , the Physiotherapy Evidence Database (PEDro) (1980 to July 2011), Allied & Complementary Medicine (AMED) (1985 to May 2011), CINAHL (1982 to May 2011).

SELECTION CRITERIA

Randomised controlled trials comparing IS with any type of prophylactic physiotherapy for prevention of postoperative pulmonary complications in adults undergoing CABG.

DATA COLLECTION AND ANALYSIS

Two reviewers independently evaluated trial quality using the guidelines of the Cochrane Handbook for Systematic Reviews and extracted data from included trials. For continuous outcomes, we used the generic inverse variance method for meta-analysis and for dichotomous data we used the Peto Odds Ratio.

MAIN RESULTS

This update included 592 participants from seven studies (two new and one that had been excluded in the previous review in 2007. There was no evidence of a difference between groups in the incidence of any pulmonary complications and functional capacity between treatment with IS and treatment with physical therapy, positive pressure breathing techniques (including continuous positive airway pressure (CPAP), bilevel positive airway pressure (BiPAP) and intermittent positive pressure breathing (IPPB), active cycle of breathing techniques (ACBT) or preoperative patient education. Patients treated with IS had worse pulmonary function and arterial oxygenation compared with positive pressure breathing. Based on these studies there was no improvement in the muscle strength between groups who received IS demonstrated by maximal inspiratory pressure and maximal expiratory pressure .

AUTHORS' CONCLUSIONS

Our update review suggests there is no evidence of benefit from IS in reducing pulmonary complications and in decreasing the negative effects on pulmonary function in patients undergoing CABG. In view of the modest number of patients studied, methodological shortcomings and poor reporting of the included trials, these results should still be interpreted cautiously. An appropriately powered trial of high methodological rigour is needed to determine if there are patients who may derive benefit from IS following CABG.

Pulmonary complications of congenital heart disease

Cardiac and pulmonary pathophysiologies are closely interdependent, which makes the management of patients with congenital heart disease (CHD) all the more complex. Pulmonary complications of CHD can be structural due to compression causing airway malacia or atelectasis of the lung. Surgical repair of CHD can also result in structural trauma to the respiratory system, e.g., chylothorax, subglottic stenosis, or diaphragmatic paralysis. Disruption of the Starling forces in the pulmonary vascular system in certain types of CHD lead to alveolar-capillary membrane damage and pulmonary oedema. This in turn results in poorly compliant lungs with a restrictive lung function pattern that can deteriorate to cause hypoxemia. The circulation post single ventricle palliative surgery (the so called "Fontan circulation") poses a unique spectrum of pulmonary pathophysiology with restrictive lung function and a low pulmonary blood flow state that predisposes to thromboembolic complications and plastic bronchitis. As the population of patients surviving post CHD repair increases, the incidence of pulmonary complications has also increased and presents a unique cohort in both the paediatric and adult clinics.

The effect of blood transfusion on pulmonary permeability in cardiac surgery patients: a prospective multicenter cohort study

BACKGROUND

There is an association between blood transfusion and pulmonary complications in cardiac surgery. Mediators of increased pulmonary vascular leakage after transfusion are unknown. We hypothesized that factors may include antibodies or bioactive lipids, which have been implicated in transfusion-related acute lung injury.

STUDY DESIGN AND METHODS

We performed a prospective cohort study in two university hospital intensive care units in the Netherlands. Pulmonary vascular permeability was measured in cardiac surgery patients after receiving no, restrictive (one or two transfusions), or multiple (five or more transfusions) transfusions (n=20 per group). The pulmonary leak index (PLI), using (67) Ga-labeled transferrin, was determined within 3 hours postoperatively. Blood products were screened for bioactive lipid accumulation and the presence of antibodies.

RESULTS

The PLI was elevated in all groups after cardiac surgery. Transfused patients had a higher PLI compared to nontransfused patients (33×10(-3) ± 20×10(-3) vs. 23×10(-3) ± 11×10(-3)/min, p<0.01). The amount of red blood cell (RBC) products, but not of fresh-frozen plasma or platelets, was associated with an increase in PLI (β, 1.6 [0.2-3.0]). Concerning causative factors in the blood product, neither the level of bioactive lipids nor the presence of antibodies was associated with an increase in PLI. Patient factors such as surgery risk and time on cardiopulmonary bypass did not influence the risk of pulmonary leakage after blood transfusion.

CONCLUSIONS

Transfusion in cardiothoracic surgery patients is associated with an increase in pulmonary capillary permeability, an effect that was dose dependent for RBC products. The level of bioactive lipids or the presence of HLA or HNA antibodies in the transfused products were not associated with increased pulmonary capillary permeability.

Morbidity after paediatric cardiac surgery assessed with usage of medicines: a population-based registry study

OBJECTIVE

To examine the overall morbidity of patients who underwent surgery for congenital cardiac defect during childhood.

BACKGROUND

A congenital cardiac defect treated with surgery is seldom totally cured. The incidence of residua, sequelae, and comorbidity is quite high. The morbidity has not been thoroughly examined.

METHODS AND PATIENTS

Medication was used as an indicator of morbidity. Data from the Finnish Research Registry of Paediatric Cardiac Surgery were linked to data from the medication registry of Finland's Social Insurance Institution. This study includes 5116 patients with a mean age of 33.5 (ranged from 14.7 to 64.8) years, who had undergone surgery for congenital cardiac defect between 1953 and 1989. The use of medicines among patients in 2004 was compared with 10232 age- and sex-matched control subjects.

RESULTS

The overall use of medicines was frequent; 62% of patients and 53% of controls had purchased at least one prescribed medicine (risk ratio: 1.2, 95% confidence interval: 1.1-1.2). The number of patients using cardiovascular medicines (17%) and anti-thrombotic agents (5%) was higher than that of control subjects (risk ratio: 2.2 and 8.4). In addition, the patients needed medicinal care for epilepsy (3%), asthma (7%), and psychiatric diseases (10%) more often than did controls (risk ratio: 2.2, 1.5, and 1.3, respectively).

CONCLUSION

Patients operated on for congenital cardiac defect had more chronic diseases and used more medicines than did controls.

Partitioning of exhaled NO in ventilated patients undergoing cardiac surgery

The change in exhaled NO after cardio-pulmonary bypass remains controversial. The aims were to determine whether exhaled NO sources (alveolar or bronchial) are modified after bypass, and whether mechanical ventilation (MV) settings during bypass modify exhaled NO changes. Thirty-two patients were divided into three groups: without MV during bypass and positive end-expiratory pressure (PEEP) (n=12), dead space MV without PEEP (n=10) and dead space MV with PEEP (n=10). Alveolar NO concentration and bronchial NO flux were calculated before and 1h after surgery using a two-compartment model of NO exchange developed in spontaneous breathing patients. Whereas a significant decrease in bronchial NO was found after bypass in the two groups without PEEP during bypass, this decrease was not observed in patients with dead space ventilation with PEEP. Alveolar NO was not significantly modified whatever the ventilation settings. In conclusion, the impairment of bronchial NO seemed related to airway closure since dead space mechanical ventilation with PEEP prevented its decrease.

Strategies to prevent intraoperative lung injury during cardiopulmonary bypass

During open heart surgery the influence of a series of factors such as cardiopulmonary bypass (CPB), hypothermia, operation and anaesthesia, as well as medication and transfusion can cause a diffuse trauma in the lungs. This injury leads mostly to a postoperative interstitial pulmonary oedema and abnormal gas exchange. Substantial improvements in all of the above mentioned factors may lead to a better lung function postoperatively. By avoiding CPB, reducing its time, or by minimizing the extracorporeal surface area with the use of miniaturized circuits of CPB, beneficial effects on lung function are reported. In addition, replacement of circuit surface with biocompatible surfaces like heparin-coated, and material-independent sources of blood activation, a better postoperative lung function is observed. Meticulous myocardial protection by using hypothermia and cardioplegia methods during ischemia and reperfusion remain one of the cornerstones of postoperative lung function. The partial restoration of pulmonary artery perfusion during CPB possibly contributes to prevent pulmonary ischemia and lung dysfunction. Using medication such as corticosteroids and aprotinin, which protect the lungs during CPB, and leukocyte depletion filters for operations expected to exceed 90 minutes in CPB-time appear to be protective against the toxic impact of CPB in the lungs. The newer methods of ultrafiltration used to scavenge pro-inflammatory factors seem to be protective for the lung function. In a similar way, reducing the use of cardiotomy suction device, as well as the contact-time between free blood and pericardium, it is expected that the postoperative lung function will be improved.

Transfusion and pulmonary morbidity after cardiac surgery

BACKGROUND

True lung injury is among the leading causes of transfusion-related mortality. Pulmonary morbidity after cardiac surgery has been related to damaging effects of cardiopulmonary bypass and transfusion, but is confounded by cardiac-related events that may not reflect true lung injury. Thus, cardiac surgery poses unique challenges to criteria-specific diagnosis of transfusion-related acute lung injury (TRALI). Our objective was to determine the prevalence of pulmonary morbidity related to transfusion and whether TRALI consensus-criteria are applicable to cardiac surgery.

METHODS

A total of 16,847 patients underwent on-pump, coronary artery bypass grafting (CABG), valve, or CABG-valve surgery from September 1998 to February 1, 2006. We performed four propensity-score-matching analyses with logistic regression on probability of receiving a transfusion: total hospital red blood cell (RBC) and fresh frozen plasma (FFP) transfusion and intraoperative RBC and FFP transfusion. Outcomes included traditional cardiac-surgery-defined pulmonary morbidity and ratio of arterial partial pressure of oxygen to fractional inspired oxygen concentration (PaO(2)/FiO(2)), a criterion for TRALI.

RESULTS

Patients receiving RBC transfusion had more risk-adjusted pulmonary complications: respiratory distress 4.8% vs 1.5%, p < 0.001; respiratory failure 2.2% vs 0.39%, p < 0.0001; longer intubation times, 9.9 hours vs 7.5 hours, p < 0.0001; acute respiratory distress syndrome, 0.64% vs 0.21%, p = 0.015; and reintubation, 5.6% vs 1.3%, p < 0.0001. The FFP was similarly related to more pulmonary complications after surgery. By TRALI criteria, the majority manifested "lung injury" (PaO(2)/FiO(2) ratio < 300) but unrelated to transfusion (65% vs 64%).

CONCLUSIONS

Transfusion is associated with many measures of postoperative pulmonary morbidity. Yet the PaO(2)/FiO(2) ratio as important criterion of TRALI is unrelated to transfusion. Thus, due to the nature of cardiac surgery, application of consensus guided diagnosis of TRALI is problematic.

Redistribution of pulmonary blood flow impacts thermodilution-based extravascular lung water measurements in a model of acute lung injury

BACKGROUND

Studies using transthoracic thermodilution have demonstrated increased extravascular lung water (EVLW) measurements attributed to progression of edema and flooding during sepsis and acute lung injury. The authors hypothesized that redistribution of pulmonary blood flow can cause increased apparent EVLW secondary to increased perfusion of thermally silent tissue, not increased lung edema.

METHODS

Anesthetized, mechanically ventilated canines were instrumented with PiCCO (Pulsion Medical, Munich, Germany) catheters and underwent lung injury by repetitive saline lavage. Hemodynamic and respiratory physiologic data were recorded. After stabilized lung injury, endotoxin was administered to inactivate hypoxic pulmonary vasoconstriction. Computed tomographic imaging was performed to quantify in vivo lung volume, total tissue (fluid) and air content, and regional distribution of blood flow.

RESULTS

Lavage injury caused an increase in airway pressures and decreased arterial oxygen content with minimal hemodynamic effects. EVLW and shunt fraction increased after injury and then markedly after endotoxin administration. Computed tomographic measurements quantified an endotoxin-induced increase in pulmonary blood flow to poorly aerated regions with no change in total lung tissue volume.

CONCLUSIONS

The abrupt increase in EVLW and shunt fraction after endotoxin administration is consistent with inactivation of hypoxic pulmonary vasoconstriction and increased perfusion to already flooded lung regions that were previously thermally silent. Computed tomographic studies further demonstrate in vivo alterations in regional blood flow (but not lung water) and account for these alterations in shunt fraction and EVLW.

Pulmonary injury after cardiopulmonary bypass: beneficial effects of low-frequency mechanical ventilation

OBJECTIVE

Pulmonary dysfunction is a frequent postoperative complication after cardiac surgery with cardiopulmonary bypass, and atelectasis is thought to be one of the main causes. The aim of this study was to evaluate whether low-frequency ventilation and continuous positive airway pressure during cardiopulmonary bypass reduce postcardiopulmonary bypass lung injury.

METHODS

Eighteen Yorkshire pigs were subjected to 120 minutes of cardiopulmonary bypass (1 hour of cardioplegic arrest) followed by 90 minutes of recovery before being sacrificed. Six animals served as control with the endotracheal tube open to atmosphere during cardiopulmonary bypass. The remaining animals were divided into 2 groups of 6: One group received continuous positive airway pressure of 5 cm H(2)O, and one group received low-frequency ventilation (5/minutes) during cardiopulmonary bypass. Lung tissue biopsy and bronchoalveolar lavage samples were obtained before and 90 minutes after discontinuation of cardiopulmonary bypass for measurement of adenine nucleotide (adenosine-5'-triphosphate, adenosine diphosphate, adenosine monophosphate), lactate dehydrogenase, DNA levels, and histology. Hemodynamic data and arterial blood gases were also collected through the study.

RESULTS

The hemodynamic parameters were similar in the 3 groups. After cardiopulmonary bypass, the low-frequency ventilation group showed significantly better oxygen tension and alveolar arterial oxygen gradient, higher adenine nucleotide, lower lactate dehydrogenase levels, and reduced histologic damage in lung biopsy, as well as lower DNA levels in bronchoalveolar lavage compared with the control group. The continuous positive airway pressure group showed only significantly reduced lactate dehydrogenase levels compared with control.

CONCLUSION

Low-frequency ventilation during cardiopulmonary bypass in a pig experimental model reduces tissue metabolic and histologic damage in the lungs and is associated with improved postoperative gas exchange.

Incentive spirometry with expiratory positive airway pressure reduces pulmonary complications, improves pulmonary function and 6-minute walk distance in patients undergoing coronary artery bypass graft surgery

BACKGROUND

The use of the incentive spirometry (IS) with expiratory positive airway pressure (EPAP) to prevent postoperative pulmonary complications (PPC) after coronary artery bypass graft (CABG) is not well established. This study sought to determine the effects of IS+EPAP after CABG.

METHODS

Thirty-four patients undergoing CABG were randomly assigned to a control group or IS+EPAP group. Maximal respiratory pressures, pulmonary function test, 6-minute walk test and chest x-ray were performed at baseline as well as 1 week and 1 month after CABG.

RESULTS

Maximal inspiratory pressure was significantly higher in the IS+EPAP group compared to controls at both 1 week and 1 month (P<.001). Maximal expiratory pressure was significantly higher at 1 month compared to 1 week in IS+EPAP group (P<.01). At 1 month, forced vital capacity and forced expiratory volume in 1 second was significantly higher in IS+EPAP compared to controls (P<.05). Inspiratory capacity was higher at 1 month in IS+EPAP group compared to controls (P<.05). The distance walked in 6-minute walk test was higher at 1 month in IS+EPAP group (P<.001) compared to controls. Lastly, radiological injury score at 1 week was lower in IS+EPAP compared to controls (P<.004).

CONCLUSIONS

In patients undergoing CABG, IS+EPAP results in improved pulmonary function and 6-minute walk distance as well as a reduction in PPC.

Evaluation of Outcome Scoring Systems for Patients on Extracorporeal Membrane Oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been used in critical conditions such as life-threatening respiratory failure or postcardiotomy cardiogenic shock. This investigation compares the predictive value of Acute Physiology, Age and Chronic Health Evaluation IV (APACHE IV), earlier APACHE models, Sequential Organ Failure Assessment (SOFA), and the risk of renal failure, injury to the kidney, failure of kidney function, loss of kidney function, and end-stage renal failure (RIFLE) classification obtained on the first day of ECMO support for hospital mortality in critically ill patients.

METHODS

We reviewed the medical records of 78 critically ill patients on ECMO support at the specialized intensive care unit in a tertiary care university hospital from March 2002 to October 2005. Demographic, clinical, and laboratory variables and five scoring systems were retrospectively gathered as predicators of survival on ECMO day 1.

RESULTS

The overall mortality rate was 60.3%. The most common condition requiring ECMO was cardiogenic shock. Goodness-of-fit was good for APACHE IV but not the APACHE III model. The APACHE IV and APACHE III scoring systems displayed excellent areas under the receiver operating characteristic curve (0.922 +/- 0.030 and 0.907 +/- 0.038, respectively). Furthermore, APACHE IV correlated significantly with APACHE III scores in individual patients (r2 = 0.902; p < 0.001). Finally, cumulative survival rates at 6-month follow-up after hospital discharge differed significantly (p < 0.001 for APACHE IV < or = 49% versus APACHE IV > 49%).

CONCLUSIONS

This study confirms the grave prognosis of critically ill patients receiving ECMO support. The APACHE IV proved to be a reproducible evaluation tool with excellent prognostic abilities in these patients.