INTRODUCTION:

Sternal Wound Infections (SWIs) are a major cause of morbidity and mortality in patients undergoing Open Heart Surgery. Sternal infections can range from minor, superficial infections to open mediastinitis with invasion of the sternum, heart and great vessels. Staphylococcus species are responsible for the majority of sternal infections, but environmental sources can cause infections by other organism. Early identification and prompt treatment of SWIs is very important to improve patient outcomes.

The purpose of this article is to introduce the healthcare nursing professional the Risk Factors, Clinical Manifestations, Diagnostic Criteria, Treatment, Preventive Measures, and Nursing Considerations of SWIs.

DEFINITION:

In defining Sternal Wound Infections (SWIs) it is important to distinguish between Superficial Sternal Wound Infection (SSWI) and Deep Sternal Wound Infection (DSWI).

· A SSWI involve only the skin, subcutaneous tissue, and/or pectoralis fascia. There is no bony involvement.

· As defined by the centers for disease control and prevention, DSWI require the presence of one of the following criteria:

(i) An organism isolated from culture of mediastinal tissue or fluid.

(ii) Evidence of mediastinitis seen during operation; or

(iii)Presence of either chest pain, sternal instability, or fever (38degree Celsius), and purulent drainage from the mediastinum or isolation of an organism present in blood culture or a culture of the mediastinal area.

INCIDENCE:

The incidence of SSWI is 0.5 to 8% with an associated morbidity and mortality rate ranging from 0.5 to 9%.

RISK FACTORS ASSOCIATED WITH SWIs:

Risk factors associated with an increased incidence of SWIs range from preoperative to postoperative factors.

(a) Preoperative factors:

It includes Advanced Age, Male Gender, Cigarette Smoking, Diabetes Mellitus, Chronic Obstructive Pulmonary Disease, Obesity, Hypertension, Peripheral Vascular Disease, Aortic Calcification, Nasal carriage of Methicillin-Resistant Staphylococcus Aureus (MRSA), Need for Pre-operative use of Intra-aortic balloon pump, and Pre-operative use of Inotropes. These factors contribute to poor wound healing and wound dehiscence.

(b) Operative factors:

It includes Emergent Operations, Coronary Artery Bypass Grafting(CABG),Bilateral Internal Thoracic Artery use, Use of Inotropic agents, Prolonged operative time (>5-8hrs), Blood Transfusion, Combined CABG and Valve or Aortic surgery.

(c) Post-Operative factors:

It include use of Post operative IABP, Re-exploration, Post operative Hyperglycemia, Prolonged placement of drainage tubes and Prolonged Intensive Care Unit stay.

ETIOLOGY:

Bacterial:

Both Gram-positive and Gram-negative Microorganisms. The most common pathogen responsible for SWIs is S. aureus, which is responsible for 50% of SWIs. Other organisms involved include S. epidermidis, Enterococcus species, and Propionibacterium acnes. The most common of these organisms S. epidermidis and S. aureus, are normal flora from the skin that when introduced to the wound cause serious systemic infections and are associated with very poor outcomes.

Fungal:

SIGNS AND SYMPTOMS OF SWIs:

Early Presentation:

(4 To 5 Days of Post-Operative Period):

Fever, Chills, Lethargy, Leukocytosis, and Ongoing Chest pain. The sternal wound can remain completely closed or may have unhealed areas with purulent drainage.

Late Presentation:

(10 To 30 Days of Post Sternotomy):

Complaints of Pain, Increased purulent drainage, and Fever in the presence of an unstable sternum.

DIAGNOSTIC CRITERIA:

According to Centers of Disease Control and Prevention, DSWI are diagnosed by meeting one of the following criteria:

1. Positive Cultures from Mediastinal tissue or fluid obtained during an Invasive procedure.

2. Evidence of Mediastinitis seen during an Invasive Procedure or Histopathologic Examination

3. Atleast one of the following Signs and Symptoms: Fever, Chest Pain, or Sternal Instability

4. Atleast one of the following:

· Purulent Discharge from Mediastinal area,

· Organisms cultured from blood or discharge from Mediastinal area,

· Mediastinal widening on imaging test.

TREATMENT:

TYPE OF WOUND

TREATMENT

TYPE I WOUND

(>1 month)

· Use of Culture-Directed Antibiotics.

· Debridement, Assessment on sternum stability and wound depth followed by Simple Wound Closure,(or)Titanium Plate Fixation and Wound Closure with Muscle Flap.

TYPEII WOUND

(1-2 months)

· Use of Culture Directed Antibiotics

· Simple Wound Debridement, Wound Dressing, Sternum Stability, followed by Vacuum-Assisted Closure(VAC)and Wound Closure with Muscle Flap.

TYPEIII WOUND

(>2 months)

· Use of Culture-Directed Antibiotics during entire treatment period(about 1-4 weeks)is necessary.

· Debridement, Wound depth, Sternum stability followed by Chest wall Reconstruction using Titanium Plate Fixation and Wound Closure with Muscle Flap.

PREVENTION:

PRE-OPERATIVE PREVENTION OF STERNAL WOUND INFECTIONS:

(a) Screening for Nasal Carriers of Staphylococcus:

All cardiac surgery patients should have nasal swabs or polymerase chain reaction (PCR) testing before surgery.

(b) Nasal Disinfectants:

Routine mupirocin administration is recommended for all cardiac surgery procedures in the absence of PCR testing or Nasal cultures positive for Staphylococcal Colonization.

(c) Pre- operative Bathing:

Pre- surgical bathing with chlorhexidine may be helpful in reducing skin bacterial counts.

(d) Hypoalbuminemia and Poor Nutritional Status:

Pre- operative hypoalbuminemia is associated with an increased risk for sternal wound infections and should be corrected before surgery if possible.

(f) Remote Infections:

All distant, extra thoracic infections should be treated before cardiac surgical procedures.

(g) Pre-Operative Glycemic Control:

Optimizing glycemic control is recommended in patients with increased HbA1c levels (>7.5) and serum glucose levels >200 mg/dl before any cardiac surgery procedure.

(h) Smoking Cessation:

Smoking Cessation and aggressive Pulmonary Toilet should be performed in patients who are active smokers and those with Chronic Obstructive Pulmonary Disease.

(i) Preoperative Antibiotics:

The Preoperative Antibiotics like Intravenous Cephalosporin, Intravenous Vancomycin are administered to prevent Sternal Wound Infections.

INTRA-OPERATIVE PREVENTION OF STERNAL WOUND INFECTIONS:

(a) Antibiotics:

A cephalosporin should be administered within 60 minutes of a cardiac surgical procedures lasting >4 hours.

(b) Glycemic control:

Continuous Insulin Infusion should be initiated to maintain serum glucose level<180 mg/dl in patients diagnosed with Diabetes Mellitus.

(c)Topical antibiotics:

Topical antibiotics should be applied to the cut edges of the sternum on opening and before closing all Cardiac Surgical Procedures involving sternotomy. It is found to reduce the incidence of Sternal Wound Infections.

(d) Intraoperative Surgical Techniques:

Properly opening and closing the sternum will decrease the incidence of sternal dehiscence and subsequent sternal infections. An in advertent par median sternotomy makes it difficult to properly realign the sternum and leads to instability, dehiscence and ultimately infection.

POST-OPERATIVE PREVENTION OF STERNAL WOUND INFECTIONS:

(a) External Chest Support Vest:

External Chest Support Vest may limit the incidence of sternal dehiscence and infections.

(b) Antibiotics:

Appropriate antibiotics should be continued post operatively for not longer than 48 hours.

(c) Retained Blood, Early Extubation, Indwelling Catheters:

· Retained blood coagulum is an excellent culture medium; therefore every attempt should be made to achieve hemostasis to avoid a return to the operating room for bleeding complication, which have been associated with an increased risk of wound infections.

· Early extubation may also decrease the incidence of wound complications

· Early removal of indwelling urinary and central venous catheters has also been found to significantly decrease the incidence of wound infection.

NURSING INTERVENTIONS TO REDUCE STERNAL WOUND INFECTIONS

Pre-operative Nursing Care:

· Practice Sterile Hand washing.

· Encourage Smoking Cessation at least six weeks prior to surgery.

· Screening for Nasal MRSA

· Administer intranasal mupirocin if patient’s Nasal culture is positive for Staphylococcal colonization.

· Ensure effective pre-operative skin preparation using antiseptics prior to Cardiac Surgery to reduce the risk of Postoperative Wound Infections.

· Ensure optimal timing for administering perioperative antibiotics in open heart surgery patients to reduce Postoperative Wound Infections.

· Monitor weight of the patient.

· Provide Nutrition Recommendations to optimize nutritional status.

· Identify patients at risk for poor wound healing (e.g., immunocompromised patient’s, elderly, diabetic patients, malnourished, Re-exploration).

· Ensure adequate rest and sleep to relieve from stress and anxiety.

Intra-operative Nursing Care:

· Maintain a Sterile environment inside the Operation Theater.

· Practice Sterile Hand washing.

· Follow strict sterile techniques while assisting cardiac surgical procedures according to the protocol.

· Monitor Hemodynamic status of the patient.

· Ensure patients safety and wellbeing.

· Maintain accurate and complete written records.

· Administer prophylactic antibiotics according to the schedule.

Post-operative Nursing Care:

· Practice Sterile Hand washing and Aseptic wound care to reduce contamination.

· Encourage Airway Clearance by means of Coughing and Deep Breathing, Incentive Spirometry, Ambulation, Repositioning, and postural drainage to maximize oxygen delivery and exchange.

· Monitor pulse oximetry to detect changes in oxygenation

· Perform Pulmonary assessment to any detect changes in lungs.

· Monitor Vital Signs.

· Administer Analgesics and Antibiotics on a scheduled basis to maintain adequate pain control and to prevent from infection.

· Splint the entire ribcage while suctioning or coughing to minimize wound stress.

· Covers a newly dehisced sternal wound with sterile towels moistened with sterile saline and immediately notify the Physician to prevent wound contamination.

· Assess and Document the appearance of open wounds with each dressing change to detect evidence of Wound Healing or Wound Infection.

· Monitor the colour of the Muscle flap Reconstruction site for evidence of adequate oxygenation to identify hypoperfused Muscle flaps early.

· Protect all sternal wounds from Respiratory secretions or drainages.

· Maintain optimal glycemic control in diabetic patients.

· Consult with Dietician, Pharmacist and Physician to develop an optimal nutritional plan to provide wound healing and promote immune function.

· Ensure adequate sleep to improve Immune function, Tissue Regeneration, and ability to cope.

· Use Relaxation, Distraction, Guided Imagery and Music Therapy to enhance pain control and reduce anxiety.

· Involve the patient and family /significant others in wound care and self care of cardiac surgery patient.

· Collaborate with Cardiac Rehabilitation and/or Physical Therapy to progress Strengthening exercises and ambulation.

· Prior to discharge, ensure that the patient and family /significant others to have a clear understanding of Activity progression ,Wound care, Wound Healing, Nutrition, Medication its Action and Side effects, and Follow-up.

CONCLUSION:

Perioperative Management and Nursing care has a significant role in reducing the incidence of Sternal Wound Infections in the Modern Era of Cardiac Surgery. When Sternal Wound Infections do occur, However, prompt recognition and treatment is very important. Although treatment algorithms may vary among surgeons, Debridement and Culture-directed antibiotic administration are standard. Vacuum Assisted Closure (VAC) is a useful bridge to definite closure of sternal wounds. Muscle Flaps are often necessary to ensure successful closure. Chest Wall Reconstruction using Titanium Plate Fixation is beneficial to strengthen and stabilize the sternum there by prevent the development of complications such as Bone non union, Poor Wound Healing, and Scar Proliferation. Future Innovations addressing Sternal Wound Infections will likely involve tissue engineering and cellular-based therapy.

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Received on 31.10.2017 Modified on 13.01.2018

Int. J. Nur. Edu. and Research. 2018; 6(3):283-286.

DOI: 10.5958/2454-2660.2018.00067.4