Hypothermia as a risk factor for pediatric cardiothoracic surgical site infection

Efficiency of an algorithm for the prevention of sternal infection after cardiac surgery in children under 1 year of age: A single-center retrospective study

Background

Sternal infection is one of the most challenging complications to manage after heart surgery. The aim of our study is to evaluate the effectiveness of a developed algorithm for preventing sternal infection in pediatric patients after surgery for congenital heart disease (CHD).

Methods

We conducted a single-center study examining the treatment of 478 children with CHD. Patients were divided into 2 groups, taking into account the application of a developed management algorithm. A multivariate logistic regression analysis was used to identify the factors influencing the development of sternal infection following heart surgery using median sternotomy.

Results

A developed algorithm was applied in 308 children. In total, there were 16 cases of sternal infection (3.34 %) across both groups. Deep wound infection developed in 6 patients (1.26 %). Sternal infection developed in 2 children (0.65 %) in the first group (in which the algorithm was applied) and 14 children (8.2 %) in the second group. Deep sternal infection developed in 1 patient in the first group (0.33 %) and in 5 patients in the second group (2.94 %). As a result, perioperative risk factors as postoperative resternotomy (OR 23.315; p < 0.001), delayed sternal closure (OR 9.087; p = 0.003), development of acute renal failure (OR 5.322; p = 0.018) were associated with increased risk of infection and application of the developed algorithm resulted in a significant reduction in risk (OR 0.032; p < 0.001).

Conclusion

The suggested method for the prevention of sternal infection has significantly reduced the incidence of sternal infection after cardiac surgery in children less than 1 year of age. In patients with moderate to high risk for surgical site infection, surgeons can enhance wound healing and prevent wound infections with simple, inexpensive, and readily available tools and techniques. Surgical aspects, topical use of antibiotics, prevention of peripheral vasoconstriction, maintenance of normal oxygen delivery rates, and an individual approach to intensive care are essential.

Intraoperative hypothermia in the neonate population: risk factors, outcomes, and typical patterns

The risk factors, outcomes, and typical patterns of intraoperative hypothermia were studied in neonates to better guide the application of insulation measures in the operating room. This retrospective study enrolled 401 neonates undergoing surgery under general anaesthesia with tracheal intubation, including abdominal surgery, thoracic surgery, brain surgery, and others. The study collected basic characteristics, such as age, sex, weight, birth weight, gestational week, primary diagnosis and American Society of Anaesthesiologists (ASA) grade. Perioperative data included preoperative body temperature, length of hospital stay, length of intensive care unit (ICU) stay, intubation time, postoperative bleeding, postoperative pneumonia, postoperative death, and total cost of hospitalization. Intraoperative data included surgical procedures, anaesthesia duration, operation duration, blood transfusion, fluid or albumin infusion, and application of vasoactive drugs. The incidence of intraoperative hypothermia (< 36 °C) was 81.05%. Compared to normothermic patients, gestational week (OR 0.717; 95% CI 0.577-0.890; P = 0.003), preoperative temperature (OR 0.228; 95% CI 0.091-0.571; P = 0.002), duration of anaesthesia (OR 1.052; 95% CI 1.027-1.077; P < 0.001), and type of surgery (OR 2.725; 95% CI 1.292-5.747; P = 0.008) were associated with the risk of intraoperative hypothermia. Patients with hypothermia had longer length of ICU stay (P = 0.001), longer length of hospital stay (P < 0.001), and higher hospital costs (P < 0.001). But there were no association between clinical outcomes and intraoperative hypothermia in the multivariable regression adjusted analysis. The lowest point of intraoperative body temperature was approximately 1 h 30 min. Then, the body temperature of patients successively entered a short plateau phase and a period of slow ascent. The greatest decrease in body temperatures occurred in preterm babies and neonates with preoperative hypothermia. The lowest core temperatures that occurred in neonates with preoperative hypothermia was lower than 35 °C. This study shows that there is a high incidence of intraoperative hypothermia in the neonate population. The intraoperative body temperature of neonates dropped to the lowest point in 1-1.5 h. The greatest decrease in core temperatures occurred in preterm babies and neonates with lower preoperative temperature.

Unintended Perioperative Hypothermia and Surgical Site Infection in Children

INTRODUCTION

Unintended perioperative hypothermia is associated with surgical site infection (SSI) in adults, prompting exhaustive efforts to maintain perioperative normothermia. Although these efforts are also made for pediatric patients, the association between hypothermia and SSI has not been demonstrated in children. We sought to determine whether perioperative hypothermia and other risk factors and clinical outcomes are associated with SSI in the pediatric population.

MATERIALS AND METHODS

This case-control study took place from January 2014 through December 2016 and included patients at a National Surgical Quality Improvement Program-participant academic children's hospital. All surgical patients were included in this retrospective analysis. SSI rates were determined. A univariate analysis was performed to determine clinical factors associated with SSI. A multivariate regression analysis was then performed to determine the predictive effect of minimum perioperative temperature for SSI.

RESULTS

This study included 3541 patients, of which 92 (2.6%) developed SSI. A univariate analysis showed associations among SSI and higher perioperative temperatures, surgical specialty of otolaryngology and general surgery, and wound classification (American Society of Anesthesiologists [ASA] classification III and IV). A multivariate analysis determined the odds of SSI increased by a factor of 1.6 for every 1°C increase in minimum perioperative temperature.

CONCLUSIONS

Unintended perioperative hypothermia in our pediatric patients was inversely associated with SSI. This finding suggests that pediatric SSI prevention may not require the efforts made for adult patients to maintain normothermia.

Ultra-mini Pcnl with clear Petra® suction-evacuation access sheath and warming irrigation fluid system (Rocamed®) for stone treatment in children

INTRODUCTION

Inadvertent perioperative hypothermia (a drop in core temperature to below 36 °C) occurs because of interference with normal temperature regulation by anaesthetic drugs, skin exposure for prolonged periods and the introduction of large volumes of intravenous and irrigation fluids. If the temperature of these fluids is below core body temperature, they can cause significant heat loss. Warming irrigation fluids might prevent some of this heat loss and subsequent hypothermia and that is the role of warming irrigation fluid systems.

MATERIAL AND METHODS

The video describes prone ultra mini PCNL with suction-evacuation access sheath under warming irrigation fluid system in a 15 month-old boy with a 2 cm-600HU staghorn calculi and one stone of 7 mm-500HU in proximal ureter.

RESULTS

The surgery was performed without intraoperative complications and perioperative hypothermia was prevented. The patient started the surgery at 35.4 °C and the final temperature was 36.3 °C in 90 min of procedure, in addition to being free of stones.

CONCLUSIONS

The warming irrigation fluid system can be helpful in preventing inadvertent perioperative hypothermia in children, improving the safety of ultra mini PCNL with suction-evacuation access sheath and shows promising results with high stone-free rates and low complications.

Perioperative body temperature maintenance and occurrence of surgical site infection: A systematic review with meta-analysis

BACKGROUND

Current guidelines recommend perioperative warming as one of the strategies to prevent surgical site infection, although there are gaps in the knowledge produced on this issue.

AIM

Assess the efficacy of active warming methods to maintain perioperative patients' body temperature and its effect on the occurrence of surgical site infection.

METHODS

A systematic review with meta-analysis was carried out. PubMed, CINAHL, LiLACS, CENTRAL, and EMBASE databases were searched.

FINDINGS

Of the 956 publications identified, 9 studies were selected for quantitative synthesis and 6 for the meta-analysis. The forced-air warming system was investigated in 8 studies. The generated evidence indicated that the use of an active warming method could maintain higher average body temperature as well as could decrease the surgical site infection incidence. Exposure of the patient to temperatures below 36°C in the perioperative period increased the chances of developing this type of infection. The meta-analysis indicated that the association between perioperative active warming methods compared with others to reduce the chances of developing surgical site infection remains unclear (odds ratio = e^-3.59 = 2.718^-0.59 = 0.552, 95% confidence interval (odds ratio) = (0.269-1.135), P = 0.106 I² = 54.34%).

CONCLUSIONS

The employment of an active warming method is effective to maintain higher averages of body temperature. However, more randomized clinical trials are needed to assess the efficacy of that intervention to prevent surgical site infection.

Effects of intraoperative temperatures on postoperative infections in infants and neonates

BACKGROUND

Perioperative hypothermia has been shown to increase surgical site infection (SSI) rates in adults. We sought to characterize whether intraoperative hypothermia or hyperthermia is associated with postoperative infections in infants.

METHODS

We conducted a retrospective review of patients ≤6 months old who underwent surgical procedures from November 2013 to October 2015 at a Level I ACS Children's Surgical Center. The outcome was infections within 30 days after operation, with particular attention to SSI. Data obtained included weight and age at surgery, American Society of Anesthesiologists (ASA) physiologic status, wound class, case length, blood transfusion within 72 h of surgery, and administration of prophylactic antibiotics. Temperatures were classified as hypothermia (T < 36 °C), normothermia (T = 36.0 to 37.9 °C), and hyperthermia (T ≥ 38 °C).

RESULTS

The 885 patients had 25 SSIs (2.8%) and 11 nonsurgical site infections (1.2%). On univariate analysis, weight at surgery, higher ASA, perioperative transfusions, and longer case length were associated with higher rate of SSI. Higher median T_high, higher median T _low, and any hyperthermia were associated with higher rate of SSI. On multivariable logistic regression adjusted analyses, hyperthermia at any time during the case was associated with SSI (OR 3.47, [95% CI 1.34, 9.04], p = 0.011). Transfusions were also associated with higher SSI rates (OR 3.60 [95% CI, 1.28, 10.3], p = 0.016).

CONCLUSIONS

Intraoperative hyperthermia is associated with increased SSI rates in infants.

LEVEL OF EVIDENCE

III.

Hospital-acquired Infection: Prevalence and Outcome in Infants Undergoing Open Heart Surgery in the Present Era

Background:

The aim of this study is to evaluate the causal relation between hospital-acquired infection (HAI) and clinical outcomes following cardiac surgery in neonates and infants and to identify the risk factors for the development of HAI in this subset of patients.

Materials and Methods:

After Ethics committee approval, one hundred consecutive infants undergoing open heart surgery (OHS) between June 2015 and June 2016 were included in this prospective observational study. Data were prospectively collected. The incidence and distribution of HAI, the microorganisms, their antibiotic resistance and patients’ outcome were determined. The Centers for Disease Control and Prevention criteria were used for defining HAIs. Univariate and multivariate risk factor analysis was done using Stata 14.

Results:

Sixteen infants developed microbiologically documented HAI after cardiac surgery. Neonatal age group was found to be most susceptible. Lower respiratory tract infections accounted for majority of the infections (47.4%) followed by bloodstream infection (31.6%), urinary tract infection (10.5%), and surgical site infection (10.5%). Klebsiella (36.8%) and Acinetobacter (26.3%) were the most frequently isolated pathogens. HAI was associated with prolonged ventilation duration (P = 0.005), Intensive Care Unit stay (P = 0.0004), and hospital stay (P = 0.002). Multivariate risk factor analysis revealed that preoperative hospital stay (odds ratio [OR] 1.22, 95% confidence interval (CI) 1.6-1.39, P = 0.004), and prolonged cardiopulmonary bypass (CPB) (OR 1.03, 95% CI 1.01-1.05, P = 0.001) were associated with the development of HAI.

Conclusion:

HAI still remains a dreaded complication in infants after OHS and contributing to morbidity and mortality. Strategies such as decreasing preoperative hospital stay, CPB time, and early extubation should be encouraged to prevent HAI.

Rationale for Implementation of Warm Cardiac Surgery in Pediatrics

Cardiac surgery was developed thanks to the introduction of hypothermia and cardiopulmonary bypass in the early 1950s. The deep hypothermia protective effect has been essential to circulatory arrest complex cases repair. During the early times of open-heart surgery, a major concern was to decrease mortality and to improve short-term outcomes. Both mortality and morbidity dramatically decreased over a few decades. As a consequence, the drawbacks of deep hypothermia, with or without circulatory arrest, became more and more apparent. The limitation of hypothermia was particularly evident for the brain and regional perfusion was introduced as a response to this problem. Despite a gain in popularity, the results of regional perfusion were not fully convincing. In the 1990s, warm surgery was introduced in adults and proved to be safe and reliable. This option eliminates the deleterious effect of ischemia-reperfusion injuries through a continuous, systemic coronary perfusion with warm oxygenated blood. Intermittent warm blood cardioplegia was introduced later, with impressive results. We were convinced by the easiness, safety, and efficiency of warm surgery and shifted to warm pediatric surgery in a two-step program. This article outlines the limitations of hypothermic protection and the basic reasons that led us to implement pediatric warm surgery. After tens of thousands of cases performed across several centers, this reproducible technique proved a valuable alternative to hypothermic surgery.

Urinary tract infection in children after cardiac surgery: Incidence, causes, risk factors and outcomes in a single-center study

Nosocomial urinary tract infection (UTI) increases hospitalization, cost and morbidity. In this cohort study, we aimed to determine the incidence, risk factors, etiology and outcomes of UTIs in post-operative cardiac children. To this end, we studied all post-operative patients admitted to the Pediatric Cardiac Intensive Care Unit (PCICU) in 2012, and we divided the patients into two groups: the UTI (UTI group) and the non-UTI (control group). We compared both groups for multiple peri-operative risk factors. We included 413 children in this study. Of these, 29 (7%) had UTIs after cardiac surgery (UTI group), and 384 (93%) were free from UTIs (control group). All UTI cases were catheter-associated UTIs (CAUTIs). A total of 1578 urinary catheter days were assessed in this study, with a CAUTI density rate of 18 per 1000 catheter days. Multivariate logistic regression analysis demonstrated the following risk factors for CAUTI development: duration of urinary catheter placement (p<0.001), presence of congenital abnormalities of kidney and urinary tract (CAKUT) (p<0.0041) and the presence of certain syndromes (Down, William, and Noonan) (p<0.02). Gram-negative bacteria accounted for 63% of the CAUTI. The main causes of CAUTI were Klebsiella (27%), Candida (24%) and Escherichia coli (21%). Resistant organisms caused 34% of CAUTI. Two patients (7%) died in the UTI group compared with the one patient (0.3%) who died in the control group (p<0.05). Based on these findings, we concluded that an increased duration of the urinary catheter, the presence of CAKUT, and the presence of syndromes comprised the main risk factors for CAUTI. Gram-negative organisms were the main causes for CAUTI, and one-third of them found to be resistant in this single-center study.

A pilot and feasibility study of the plasma and tissue pharmacokinetics of cefazolin in an immature porcine model of pediatric cardiac surgery

BACKGROUND

Surgical site infection (SSI) prevention for children with congenital heart disease is imperative and methods to assess and evaluate the tissue concentrations of prophylactic antibiotics are important to help maximize these efforts.

AIM

The purposes of this study were to determine the plasma and tissue concentrations with standard of care, perioperative cefazolin dosing in an immature porcine model of pediatric cardiac surgery, and to determine the feasibility of this model.

METHODS

Piglets (3-5 days old) underwent either median sternotomy (MS) or cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB + DHCA) and received standard of care prophylactic cefazolin for the procedures. Serial plasma and microdialysis sampling of the skeletal muscle and subcutaneous tissue adjacent to the surgical site was performed. Cefazolin concentrations were measured, noncompartmental pharmacokinetic analyses were performed, and tissue penetration of cefazolin was assessed.

RESULTS

Following the first intravenous dose, maximal cefazolin concentrations in the subcutaneous tissue and skeletal muscle were similar between groups with peak tissue concentrations 15-30 min after administration. After the second cefazolin dose given with the initiation of CPB, total plasma cefazolin concentrations remained relatively constant until the end of DHCA and then decreased while muscle- and subcutaneous-unbound cefazolin concentrations showed a second peak during or after rewarming. For the MS group, 60-67% of the intraoperative time showed subcutaneous and skeletal muscle concentrations of cefazolin >16 μg·ml(-1) while this percentage was 78-79% for the CPB + DHCA group. There was less tissue penetration of cefazolin in the group that underwent CBP + DHCA (P = 0.03).

CONCLUSIONS

The cefazolin dosing used in this study achieves plasma and tissue concentrations that should be effective against methicillin-sensitive Staphylococcus aureus but may not be effective against some gram-negative pathogens. The timing of the cefazolin administration prior to incision and a second dose given during cardiopulmonary bypass may be important factors for achieving goal tissue concentrations.

Nasal methicillin-resistant S. aureus is a major risk for mediastinitis in pediatric cardiac surgery

BACKGROUND

Mediastinitis caused by methicillin-resistant Staphylococcus aureus (MRSA) is a serious complication after pediatric cardiac surgery. An outbreak of surgical site infections (SSIs) provided the motivation to implement SSI prevention measures in our institution.

METHODS

Subjects comprised 174 pediatric patients who underwent open-heart surgery after undergoing preoperative nasal culture screening. The incidence of SSIs and mediastinitis was compared between an early group, who underwent surgery before SSI measures (Group E, n = 73), and a recent group, who underwent surgery after these measures (Group R, n = 101), and factors contributing to the occurrence of mediastinitis were investigated.

RESULTS

The incidence of both SSIs and Mediastinitis has significantly decreased after SSI measures. With regard to factors that significantly affected mediastinitis, preoperative factors were "duration of preoperative hospitalization" and "preoperative MRSA colonization," intraoperative factors were "Aristotle basic complexity score," "operation time," "cardiopulmonary bypass circuit volume" and "lowest rectal temperature." And postoperative factor was "blood transfusion volume." Patients whose preoperative nasal cultures were MRSA-positive suggested higher risk of MRSA mediastinitis.

CONCLUSIONS

SSI prevention measures significantly reduced the occurrence of SSIs and mediastinitis. Preoperative MRSA colonization should be a serious risk factor for mediastinitis following pediatric cardiac surgeries.

Risk Factors Associated With Surgical Site Infection After Pediatric Posterior Spinal Fusion Procedure

Objective.

To identify risk factors associated with surgical site infection (SSI) after pediatric posterior spinal fusion procedure by examining characteristics related to the patient, the surgical procedure, and tissue hypoxia.

Design.

Retrospective case-control study nested in a hospital cohort study.

Setting.

A 475-bed, tertiary care children's hospital.

Methods.

All patients who underwent a spinal fusion procedure during the period from January 1995 through December 2006 were included. SSI cases were identified by means of prospective surveillance using National Nosocomial Infection Surveillance system definitions. Forty-four case patients who underwent a posterior spinal fusion procedure and developed an SSI were identified and evaluated. Each case patient was matched (on the basis of date of surgery, ± 3 months) to 3 control patients who underwent a posterior spinal fusion procedure but did not develop an SSI. Risk factors for SSI were evaluated by univariate analysis and multivariable conditional logistic regression. Odds ratios (ORs), with 95% confidence intervals (CIs) andPvalues, were calculated.

Results.

From 1995 to 2006, the mean annual rate of SSI after posterior spinal fusion procedure was 4.4% (range, 1.1%—6.7%). Significant risk factors associated with SSI in the univariate analysis included the following: a body mass index (BMI) greater than the 95th percentile (OR, 3.5 [95% CI, 1.5–8.3]); antibiotic prophylaxis with clindamycin, compared with other antibiotics (OR, 3.5 [95% CI, 1.2 10.0]); inappropriately low dose of antibiotic (OR, 2.6 [95% CI, 1.0–6.6]); and a longer duration of hypothermia (ie, a core body temperature of less than 35.5°C) during surgery (OR, 0.4 [95% CI, 0.2–0.9]). An American Society of Anesthesiologists (ASA) score of greater than 2, obesity (ie, a BMI greater than the 95th percentile), antibiotic prophylaxis with clindamycin, and hypothermia were statistically significant in the multivariable model.

Conclusion.

An ASA score greater than 2, obesity, and antibiotic prophylaxis with clindamycin were independent risk factors for SSI. Hypothermia during surgery appears to provide protection against SSI in this patient population.

Thermoregulation and Risk of Surgical Site Infection

Surgical site infections (SSIs) occur in approximately 2%–5% of patients undergoing surgery in the acute care setting in the United States. These infections result in increased length of stay, higher risk of death, and increased cost of care compared with that in uninfected surgical patients. Given the inclusion of maintenance of perioperative normothermia for all major surgeries as a means of lowering the risk of infection in the Surgical Care Improvement Project 2009, we prepared a summary of the literature to determine the strength and quantity of the evidence underlying the performance measure. Although the data are generally supportive of perioperative normothermia as a means of reducing the risk of SSIs, a more rigorous approach using standard SSI definitions as well as standardized temperature measurements (and timing thereof) will further delineate the role played by temperature regulation in SSI development.

Skeletal muscle and plasma concentrations of cefazolin during cardiac surgery in infants

OBJECTIVE

To describe the pharmacokinetics and tissue disposition of prophylactic cefazolin into skeletal muscle in a pediatric population undergoing cardiac surgery.

METHODS

The subjects included 12 children, with a median age of 146 days (interquartile range, 136-174) and median weight of 5.5 kg (interquartile range, 5.2-7.3) undergoing cardiac surgery and requiring cardiopulmonary bypass with or without deep hypothermic circulatory arrest. Institutional cefazolin at standard doses of 25 mg/kg before incision and 25 mg/kg in the bypass prime solution were administered. Serial plasma and skeletal muscle microdialysis samples were obtained intraoperatively and the unbound cefazolin concentrations measured. Noncompartmental pharmacokinetic analyses were performed and the tissue disposition evaluated.

RESULTS

After the first dose of cefazolin, the skeletal muscle concentrations peaked at a median microdialysis collection interval of 30 to 38.5 minutes. After the second dose, the peak concentrations were delayed a median of 94 minutes in subjects undergoing deep hypothermic circulatory arrest. Skeletal muscle exposure to cefazolin measured by the area under concentration time curve 0-last measurement was less in the subjects who underwent deep hypothermic circulatory arrest than in those who received cardiopulmonary bypass alone (P = .04). The skeletal muscle concentrations of cefazolin exceeded the goal concentrations for methicillin-sensitive Staphylococcus aureus prophylaxis; however, the goal concentrations for gram-negative pathogens associated with surgical site infections were achieved only 42.1% to 84.2% and 0% to 11.2% of the intraoperative time in subjects undergoing cardiopulmonary bypass alone or deep hypothermic circulatory arrest, respectively.

CONCLUSIONS

This cefazolin dosing strategy resulted in skeletal muscle concentrations that are likely not effective for surgical prophylaxis against gram-negative pathogens but are effective against methicillin-sensitive S aureus in infants undergoing cardiac surgery.

Delayed sternal closure after pediatric cardiac operations; single center experience: a retrospective study

BACKGROUND

Delayed sternal closure (DSC) after cardiac surgery is a therapeutic option in the treatment of the severely impaired heart in pediatric cardiac surgery. The results with the technique of DSC over a 4-year period are examined with regard to mortality and morbidity.

METHODS

We retrospectively reviewed records of 38 patients who had undergone DSC among 1100 congenital cardiac operations. Indication of DSC, time to sternal closure, pre and post closure cardiopulmonary and metabolic status, mortality, rate of wound and bloodstream infections were recorded.

RESULTS

The mean sternal closure time was 2.9 days. The mortality rate was 34.2% (n = 13). Twenty (52.6%) patients required prolonged antibiotic use due to postoperative infection. There was gram negative microorganism predominance. There were 4 (10.5%) patients with postoperative mediastinitis. Postoperative infection rate statistically increased with cardiopulmonary bypass time (CPBT), sternal closure time (SCT) and intensive care unit (ICU) stay time (p = 0.039;p = 0.01;p = 0.012). On the other hand, the mortality rate significantly increased with increased cross clamp time (CCT), SCT, and extracorporeal membrane oxygenation (ECMO) use (p = 0.017; p = 0.026; p = 0.03). Single ventricular physiology was found to be risk factor for mortality in delayed sternal closure (p < 0.007).

CONCLUSIONS

Elective DSC does not reduce the morbidity. The prolonged sternal closure time is associated with increased rate of postoperative infection rate; therefore early closure is strongly advocated.

The effects of intraoperative hypothermia on surgical site infection: an analysis of 524 trauma laparotomies

OBJECTIVES

Our primary study objective was to determine whether intraoperative hypothermia predisposes patients to postoperative surgical site infections (SSI) after trauma laparotomy.

BACKGROUND

Although intraoperative normothermia is an important quality performance measure for patients undergoing colorectal surgery, the effects of intraoperative hypothermia on SSI remain unstudied in trauma.

METHODS

A review of all patients (July 2003-June 2008) who survived 4 days or more after urgent trauma laparotomy at a level I trauma center revealed 524 patients. Patient characteristics, along with preoperative and intraoperative care focusing on SSI risk factors, including the depth and duration of intraoperative hypothermia, were evaluated. The primary outcome measure was the diagnosis of SSI within 30 days of surgery. Cut-point analysis of the entire range of lowest intraoperative temperature measurements established the temperature nadir that best predicted SSI development. Single and multiple variable logistic regression determined SSI predictors.

RESULTS

The mean intraoperative temperature nadir of the study population (n = 524) was 35.2°C ± 1.1°C and 30.5% had at least 1 temperature measurement less than 35°C. Patients who developed SSI (36.1%) had a lower mean intraoperative temperature nadir (P = 0.009) and had a greater number of intraoperative temperature measurements <35°C (P < 0.001) than those who did not. Cut-point analysis revealed an intraoperative temperature of 35°C as the nadir temperature most predictive of SSI development. Multivariate analysis determined that a single intraoperative temperature measurement less than 35°C independently increased the site infection risk 221% per degree below 35°C (OR: 2.21; 95% CI: 1.24-3.92, P = 0.007).

CONCLUSIONS

Just as intraoperative hypothermia is an SSI risk factor in patients undergoing elective colorectal procedures, intraoperative hypothermia less than 35°C adversely affects SSI rates after trauma laparotomy. Our results suggest that intraoperative normothermia should be strictly maintained in patients undergoing operative trauma procedures.

Bloodstream infections increased after delayed sternal closure: cause or coincidence

BACKGROUND

Infants who undergo major cardiac operations are at risk for developing bloodstream infections which contribute to the morbidity, mortality, and cost of treatment. Determining what factors are associated with this increased risk of infection may aid in prevention. We sought to evaluate the practice of delayed sternal closure after neonatal cardiac surgery to determine its role as a risk factor for postoperative bloodstream infection.

METHODS

We reviewed 110 consecutive patients with hypoplastic left heart syndrome after stage 1 Norwood procedure at Children's Healthcare of Atlanta. The rates of bloodstream infections were determined and risks analyzed with regard to postoperative status of sternal closure; primary versus delayed.

RESULTS

Delayed sternal closure was utilized in 67 of 110 patients (61%), while 43 patients had primary sternal closure in the operating room. Overall rate of bloodstream infection was 22% (24 of 110), with 83% (20 of 24) of infections occurring in the delayed closure group. Among infants with delayed closure, 30% developed bloodstream infection, as compared with 9% of patients with primary closure (p = 0.017). Patients with delayed closure had a fourfold increased risk (odds ratio 3.9, p = 0.03) of developing bloodstream infection in-hospital. Predominant organisms were coagulase negative Staphylococcus species; there was one case of mediastinitis.

CONCLUSIONS

Delayed sternal closure is associated with an increased likelihood of bloodstream infection and should be recognized as a risk factor after neonatal cardiac operations.

Risk factors and risk adjustment for surgical site infections in pediatric cardiothoracic surgery patients

BACKGROUND

The complexity of congenital cardiac defects and the aggressive medical management required to support patients through their recovery place children at high risk for surgical site infection (SSI).

METHODS

We conducted a retrospective review of children undergoing cardiothoracic surgery at a tertiary care referral center between January 1, 2000, and June 30, 2001. Preoperative, intraoperative, and postoperative data were assessed by multivariate analysis.

RESULTS

Of 726 surgical procedures performed in 626 patients, SSIs occurred after 46 procedures performed in 46 patients (6.3%). Infections were superficial (n = 22; 47.8%), deep tissue (n = 7; 15.2%), or organ space (n = 17; 37.0%), including 5 episodes of mediastinitis. Median time to SSI was 10 days; 36% of the infections were identified after discharge. On multivariate analysis, children with SSIs were more likely to have been <30 days old (odds ratio [OR], 2.9; 95% confidence interval [CI], 1.2-70), to have a perioperative medical device, and to use parenteral nutrition (OR, 3.3; 95% CI, 1.4-7.9). Multiple severity of illness scores, the Risk Adjustment for Congenital Heart Surgery (RACHS-1) category, and longer duration of postoperative antimicrobials were not associated with SSI.

CONCLUSION

The use of perioperative medical interventions increases the risk of SSI in young children after cardiac surgery. Prolonged postoperative courses of antimicrobials should be avoided in the absence of documented infection.

Major infection after pediatric cardiac surgery: a risk estimation model

BACKGROUND

In pediatric cardiac surgery, infection is a leading cause of morbidity and mortality. We created a model to predict risk of major infection in this population.

METHODS

Using the Society of Thoracic Surgeons Congenital Heart Surgery Database, we created a multivariable model in which the primary outcome was major infection (septicemia, mediastinitis, or endocarditis). Candidate-independent variables included demographic characteristics, comorbid conditions, preoperative factors, and cardiac surgical procedures. We created a reduced model by backward selection and then created an integer scoring system using a scaling factor with scores corresponding to percent risk of infection.

RESULTS

Of 30,078 children from 48 centers, 2.8% had major infection (2.6% septicemia, 0.3% mediastinitis, and 0.09% endocarditis). Mortality and postoperative length of stay were greater in those with major infection (mortality, 22.2% versus 3.0%; length of stay >21 days, 69.9% versus 10.7%). Young age, high complexity, previous cardiothoracic operation, preoperative length of stay more than 1 day, preoperative ventilator support, and presence of a genetic abnormality were associated with major infection after backward selection (p < 0.001). Estimated infection risk ranged from less than 0.1% to 13.3%; the model discrimination was good (c index, 0.79).

CONCLUSIONS

We created a simple bedside tool to identify children at high risk for major infection after cardiac surgery. These patients may be targeted for interventions to reduce the risk of infection and for inclusion in future clinical trials.

Continuous Infusion of Nafcillin for Sternal Osteomyelitis in an Infant After Cardiac Surgery

We report the use of the continuous infusion of nafcillin for the treatment of an infant who had methicillinsusceptible Staphylococcus aureus sternal osteomyelitis not responsive to traditional nafcillin dosing. The patient was successfully treated with surgical debridement and the continuous infusion of nafcillin. To our knowledge, this is the first report describing the successful use of the continuous infusion of nafcillin to treat an infant who had sternal osteomyelitis after cardiac surgery.

The "six sigma approach" to the operating room environment and infection

The patient's external environment plays a significant, and in some cases dominant, role in his or her infection risk. The use of ultraclean air for certain procedures, as well as avoidance of hypothermia have been proven to reduce the risk of infection. There is no data to support the routine use of surgical masks (by surgeons or staff), ventilating helmets, or routine cleaning of all environmental surfaces in between cases. More research needs to be done in order to determine whether OR design changes, in addition to increasing OR efficiency and thus reducing case times, can also reduce infection rates. Further research is also needed to determine whether or not double gloves and/or the use of antiseptic scrubbing in addition to painting are efficacious.

Postoperative hyperglycemia is associated with mediastinitis following pediatric cardiac surgery

INTRODUCTION

Mediastinitis is an infrequent, but significant complication of median sternotomy. Perioperative hyperglycemia is associated with increased morbidity, including infection in pediatric and adult cardiac surgical patients. We hypothesized that perioperative blood glucose levels would be higher in patients who later developed mediastinitis.

METHODS

We examined the medical records of all infants and children diagnosed with poststernotomy mediastinitis (n = 24) from July 2001 to December 2005. Data recorded included postoperative blood glucose levels, age, diagnosis, operation, surgical complexity score, duration of operation and cardiopulmonary bypass, delayed sternal closure, perioperative use of steroids and total parenteral nutrition, and duration of postoperative inotropic and ventilatory support. Records of patients without mediastinitis matched for age, complexity score, and month of operation (control group, n = 32) were also reviewed. Data were analyzed with t-tests and chi-square tests. Variables with P < 0.21 on univariate tests were entered into a multivariate logistic regression model.

RESULTS

Initially, postoperative blood glucose levels were elevated, but similar in both mediastinitis and control groups. The number of subjects having peak blood glucose levels >7.2 mm (>130 mg.dl(-1)) during the first 24 h was greater in the mediastinitis group (P = 0.07). The significant multivariate predictor of mediastinitis was 24 h peak blood glucose >7.2 mM (>130 mg.dl(-1)) (P = 0.039).

CONCLUSION

Our data support the hypothesis that postoperative hyperglycemia is a risk factor for the development of mediastinitis in infants and children following cardiac surgery.

Risk factors for sternal wound infection in children undergoing cardiac surgery: a case-control study

SUMMARY

Complex and prolonged cardiovascular operations are increasingly performed on young infants and children. The aims of this study were to define the incidence, causative bacterial pathogens and risk factors for sternal wound infections (SWIs) in infants and children undergoing cardiac surgery. The study group included all children who underwent cardiac surgery by median sternotomy at a tertiary paediatric centre from 1999 to 2003 and who were diagnosed with a postoperative SWI. Charts were reviewed for pre-, intra- and postoperative variables. The findings were compared with control patients operated on immediately before and after the cases and analysed by a stepwise logistic regression model. Of the 1821 children who underwent cardiac surgery, 49 (2.69%) had SWI; full data were available for 47. Twenty-nine (61.7%) had superficial wound infection and 18 (38.3%) deep wound infection. The main bacterial pathogens were Staphylococcus aureus in 14 patients (39%) and Pseudomonas aeruginosa in 12 (33%). Three variables emerged as significant independent risk factors for SWI: young age (odds ratio: 0.63; 95% confidence interval: 0.47-0.85; P<0.001 for each additional year), cyanotic heart disease (4.93; 1.98-12.3; P<0.001), and central venous catheter (CVC) dwell time (1.15; 1.06-1.24; P<0.001 for each additional day). Gram-negative infections were significantly associated with preoperative oxygen treatment (P=0.007) and prolonged urinary catheter dwell time (P=0.004). This study confirms younger age as risk factor for SWI and adds cyanotic heart disease and duration of CVC as new independent risk factors. Specific risks for Gram-negative infections are identified and should help to introduce new preventive strategies to decrease the incidence and severity of SWI.

Case-control study of pediatric cardiothoracic surgical site infections

A retrospective case-control study was performed to determine the risks and outcomes associated with pediatric cardiothoracic surgical site infection. Undergoing more than 1 cardiothoracic operative procedure, having preoperative infection, and undergoing surgery on a Monday were significant risk factors. Cardiothoracic surgical site infection increased hospital and pediatric intensive care unit length of stay. Deep surgical site infection significantly increased mortality.

Risk factors for mediastinitis following median sternotomy in children

BACKGROUND

Mediastinitis is a devastating complication of pediatric cardiothoracic surgery. However, risk factors for the development of mediastinitis are poorly characterized. The objective of this study was to identify risk factors for mediastinitis in a cohort of children undergoing cardiothoracic surgery at a tertiary care children's hospital.

METHODS

This case-control study included patients who underwent median sternotomy between January 1, 1995 and December 31, 2003. Univariate analyses, logistic regression, and multinomial regression were performed to determine the association between potential risk factors and the development of mediastinitis.

RESULTS

Forty-three patients with mediastinitis and 184 patients without mediastinitis were included. One hundred and twelve (49%) patients were female. The median patient age was 128 days (interquartile range: 7 days-2.0 years). A known or possible genetic syndrome was present in 53 (24%) patients. The following factors were associated with the development of mediastinitis: presence of a known or possible genetic syndrome (adjusted odds ratio, OR: 4.5; 95% confidence interval, CI: 1.8-11.4); American Society of Anesthesiologists score >3 (adjusted OR: 3.4; 95% CI: 1.1-10.3); and presence of intracardiac pacing wires for >3 days (adjusted OR: 15.8; 95% CI: 2.0-127.2).

CONCLUSIONS

The presence of a known or possible genetic syndrome, American Society of Anesthesiologists score >3, and the presence of intracardiac pacing wires for >3 days were each associated with the development of mediastinitis in children after median sternotomy.

Water-filled garment warming of infants undergoing open abdominal or thoracic surgery

We have assessed the efficacy of a water-filled garment (ThermoWrap-Allon 2001) to maintain normothermia in small infants during major open abdominal or thoracic surgery. Twenty-two patients were studied in a case-matched comparison of two methods of thermal control intended to maintain core body temperature at 37 degrees C. The standard method involved a warm air mattress with additional insulation. The ThermoWrap garment covered the head, trunk and legs and the water temperature was automatically controlled. Central and peripheral temperatures were recorded every 15 min. Nineteen infants had abdominal and three had thoracic operations. The mean weight was 3.2 kg (range 1.4-7.8 kg). Over time, the core temperature declined with standard care but not with the ThermoWrap. Core temperature was statistically lower in the standard care infants by 30 min after start of surgery. Six infants had a core temperature of less than 35 degrees C with standard care (lowest 33.7 degrees C); the lowest temperature with the ThermoWrap was 35.6 degrees C. Some infants had cold hands with the ThermoWrap. Core temperature is better preserved with the ThermoWrap; extra insulation of exposed arms may be necessary. An important advantage of the ThermoWrap is its ability to control body temperature automatically.

Pediatric Poststernotomy Mediastinitis

BACKGROUND

Mediastinitis results in significant morbidity in pediatric cardiac patients. It is not clear whether delayed sternal closure is a risk factor for these infections. Management of mediastinitis remains controversial.

METHODS

Cases of mediastinitis at the Stollery Children's Hospital from January 1, 1991, to June 30, 2004, were reviewed.

RESULTS

There were 29 cases of mediastinitis in 2,675 open cardiac procedures for an overall incidence of 1.1%. Infection was diagnosed 5 to 27 days after the original surgical procedure (median, 10 days). The odds ratio for infection with delayed sternal closure versus primary sternal closure was 1.88 (95% confidence interval, 0.63 to 5.60). Signs at the onset of infection included fever (86%), incisional erythema (69%), purulent drainage from the incision or pacer wire sites (83%), and wound dehiscence (23%). Debridement was followed by primary sternal closure in all but three cases in which the sternum had not been closed before debridement and rotational muscle flaps were not used. Continuous irrigation systems were used only in the first 7 patients. One patient died of mediastinitis complicated by infective endocarditis, and 2 patients died of multiorgan failure.

CONCLUSIONS

Delayed sternal closure was not a major risk factor for mediastinitis, especially if primary skin closure was used with delayed sternal closure. Excellent results were attained with debridement and primary closure of these infections.

Postoperative mediastinitis in children: epidemiology, microbiology and risk factors for Gram-negative pathogens

BACKGROUND

Mediastinitis, although an infrequent complication of median sternotomy, represents a significant source of morbidity and mortality.

OBJECTIVE

To determine the incidence and describe the epidemiology and microbiology of mediastinitis in children after cardiac surgery and to identify risk factors for the development of Gram-negative mediastinitis.

STUDY DESIGN

This was a retrospective case-control study nested within the cohort of children, birth to 18 years of age, undergoing median sternotomy between January 1, 1995 and December 31, 2003.

RESULTS

Forty-three cases of mediastinitis were identified. The incidence of mediastinitis was 1.4%. Median patient age at time of inciting sternotomy was 32 days (interquartile range, 5 days-9 months). Twenty-three (54%) cases occurred in girls. Median time to onset of infection after surgery was 11 days (range, 4-34 days). Overall Gram-positive organisms were present in 29 (67%) cases, and Gram-negative organisms were present in 13 (30%) cases. The organisms most commonly isolated from mediastinal culture were Staphylococcus aureus (46%), coagulase-negative staphylococci (17%) and Pseudomonas aeruginosa (17%). The rate of concurrent bacteremia was 53% (95% confidence interval, 38-69%). In multivariable analysis, delayed sternal closure was an independent risk factor for the development of Gram-negative mediastinitis (odds ratio, 9.3; 95% confidence interval, 1.5-56.8; P = 0.016).

CONCLUSIONS

Although Gram-positive organisms were the most common cause of infection, Gram-negative organisms accounted for one-third of all isolates. More than one-half of patients with mediastinitis had concurrent bacteremia. Delayed sternal closure was an independent risk factor for Gram-negative mediastinitis.

Prevention of postsurgical infections: some like it hot

PURPOSE OF THE REVIEW

The present review covers the literature on prevention of surgical site infections published during 2001. Only papers that offer new insights or question current recommendations are included.

RECENT FINDINGS

The most interesting advances have been made in the preoperative preparation of the patient. In particular, the effects of preoperative warming of the patient, either generally or locally at the incision site, on the rate of surgical site infections are impressive and warrant further investigation. Also, the effects of strict control of perioperative blood glucose levels and of preoperative eradication of nasal carriage of Staphylococcus aureus should be studied in greater detail.

SUMMARY

The protective effect of local and systemic warming before surgical procedures has been described in two well designed studies. Although a final judgement regarding effectiveness can only be made after more extensive investigations have been conducted, there appear to be few arguments against application of this cheap and safe measure. Thus, implementation of preoperative warming can be justified in settings associated with high rates of surgical site infections.