# Presentation: 881542

## Prevention of Surgical Site Infections: Considerations in Measuring Effectiveness

**Michele L. Pearson, MD**
**Division of Healthcare Quality Promotion**
**National Center for Infectious Diseases**

## Objectives

- Provide overview of epidemiology of surgical site infections (SSI)
- Discuss SSI prevention strategies
- Highlight current surveillance systems for SSI
- Provide overview of HICPAC/CDC process for developing recommendations for prevention healthcare-associated infections

## Public Health Importance of Surgical Site Infections

- In U.S., >40 million inpatient surgical procedures each year; 2-5% complicated by surgical site infection
- SSIs second most common nosocomial infection (24% of all nosocomial infections)
- Prolong hospital stay by 7.4 days
- Cost $400-$2,600 per infection (TOTAL: $130-$845 million/year)

## CDC Definition of Surgical Site Infections

**    ****Incisional SSI**
**      ****- Superficial incisional = skin and**
**	****subcutaneous tissue**
**      ****- Deep incisional = involving deeper soft ****	****	****tissue**
**    ****Organ/Space SSI**
**      ****- Involve any part of the anatomy (organs**
**	****and spaces), other  than the incision, ****	****	****	****opened or manipulated during operations**
**	**

**CDC Definition of Surgical Site Infections**

## Cross Section of Abdominal Wall Depicting CDC SSI Classifications

**Cross Section of Abdominal Wall Depicting CDC SSI Classifications**

## Source of SSI Pathogens

- Endogenous flora of the patient
- Operating theater environment
- Hospital personnel (MDs/RNs/staff)
- Seeding of the operative site from distant focus of infection (prosthetic device, implants)

## Microbiology of SSIs

**1986-1989**
**(N=16,727)**

**1990-1996**
**(N=17,671)**

## Microbiology of SSIs 

- Unusual pathogens
*	**•**	**Rhizopus oryzea* - elastoplast adhesive 	bandage
*	**•**	**Clostridium perfringens* - elastic bandages
*	**•**	**Rhodococcus bronchialis* - colonized 	health care personnel
*	**•**	**Legionella dumoffii* and *pneumophila* - tap 	water
*	**•**	**Pseudomonas multivorans* - disinfectant 	solution
- Cluster of unusual SSI pathogens  formal epidemiologic investigation

## Pathogenesis of SSI

- Relationship equation																																												**Dose of bacterial contamination x Virulence ****	****	****	****   ****	**** ****	****	****	****	****	****Resistance of host****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****	****   ****	****	****SSI Risk****	****	**

## SSI Risk Factors

- Age
- Obesity
- Diabetes
- Malnutrition
- Prolonged preoperative stay
- Infection at remote site
- Systemic steroid use
- Nicotine use

- Hair removal/Shaving
- Duration of surgery
- Surgical technique
- Presence of drains
- Inappropriate use of antimicrobial prophylaxis

## Perioperative Preventive Measures

## Role of Antimicrobial Prophylaxis (AP) in Preventing SSI

- Refers to very brief course of an antimicrobial agent initiated just before the operation begins
- Should be viewed as an _adjunctive_ preventive measure
- Appropriately administered AP associated with a 5-fold decrease in SSI rates

## Importance of Timing of Surgical Antimicrobial Prophylaxis (AP) 

- Prospective study of 2,847 elective clean and clean-contaminated procedures
- Early AP (2-24 hrs before incision):	3.8%  Postop AP (3-24 hrs after incision):	3.3%     Periop AP (< 3 hrs after incision):	1.4%  Preop AP (<2 hrs before incision):	0.6%

- Classen, 1992 (NEJM 326:281-286)

## Impact of Prolonged Surgical Prophylaxis

- DESIGN: Prospective
- POPULATION: CABG patients (N=2641)
- 		Group 1: pts who received _<_ 48 hours of 			AP
- 		Group 2: pts who received > 48 hrs of AP

## Impact of Prolonged Surgical AP

- _OUTCOMES_
- 	•	Incidence of SSI
- 	•	Isolation of a resistant pathogen
- _RESULTS_:  43% of patients received AP > 48 hr
- 	_SSI_ _Incidence_
- 	•	_<_48 hrs group:  8.7% (131/1502) vs
- 	•	>48 hrs group:  8.8% (100/1139), p=1.0 _Antimicrobial resistant pathogen _
- 	•	 OR 1.6 (95% CI 1.1-2.6)

## Enhanced Perioperative Glucose Control in Diabetic Patients

- DESIGN: Prospective, sequential study
- POPULATION: Diabetic patients undergoing cardiac surgery (N=2467) during 1987-1997
- 		_Controls_: pts who received intermittent 	subQ insulin (SQI)
- 		_Treated_: pts who received continuous 	intravenous (IV) insulin

**Furnary AP; Ann Thorac Surg, 2000**

## Enhanced Perioperative Glucose Control in Diabetic Patients

- _OUTCOMES_
- 	•	Blood glucose <200 mg/dl in first two 	days postop
- 	•	Incidence of deep sternal SSI
- _RESULTS_
- 	•	SQI group:  2.0% (19/968) vs
- 	•	IVI group:    0.8% (12/1499), p=0.01

**Furnary AP; Ann Thorac Surg, 2000**

## Supplemental Perioperative O2 

- DESIGN:  Randomized controlled trial, double blind
- POPULATION: Colorectal surgery (N=500)
- INTERVENTION: 30% vs 80% inspired oxygen during and up to hours after surgery
- RESULTS:  SSI incidence 5.2%  (80% O2) vs 11.2% (30% O2), p=0.01

**Greif, R, et al , NEJM, 2000**

## Pre-operative Antiseptic Showers/Baths

**	****antiseptic showering decreases colony counts**
**Few studies examine effect on SSI rates**
**	****	****	****	****	**_**No Shower**_**	**_**Shower**_
**	****Cruse, 1973****	****	****     2.3%****	****	****  1.3%**
**	****	**
**	****Ayliffe, 1983****	****	****     4.9%****	****	****  5.4%**
**	****	**
**	****Rooter, 1988****	****	****     2.4%****	****	****  2.6%**
**	****	**

**Pre-operative Antiseptic Showers/Baths**

## Pre-operative Shaving/Hair Removal

**	**_**Method of hair removal**_
**	****	****Razor****	****= 5.6% SSI rates**
**	****	****Depilatory****	****= 0.6% SSI rates**
**	****	****No hair removal****	****= 0.6% SSI rates**
_**	**__**Timing of hair removal**_
**	****Shaving immediately before****	****= 3.1% SSI rates**
**	****Shaving ******** 24 hours before****	****= 7.1% SSI rates**
**	****Shaving >24 hours before****	****= 20% SSI rates**

**Pre-operative Shaving/Hair Removal**

## Pre-operative Shaving/Hair Removal

**Multiple studies show**
**      **
**	****-  Clipping immediately before operation ****	****   associated with lower SSI risk than ****	****   shaving or clipping the night before ****	****   operation**

**Pre-operative Shaving/Hair Removal**

## Surgical Attire

- Scrub suits
- Cap/hoods
- Shoe covers
- Masks
- Gloves
- Gowns

## Surgical Technique

- Removing devitalized tissue
- Maintaining effective hemostasis
- Gently handling tissues
- Eradicating dead space
- Avoiding inadvertent entries into a viscus
- Using drains and suture material appropriately

## Parameters for Operating Room Ventilation*

- _Temperature_:	68o-73oF, depending on 				normal ambient temp
- _Relative humidity_:	30%-60%
- _Air movement_:	from “clean to less clean” 				areas
- _Air changes_:		_>_15 total per hour  					_>_3 outdoor air per hour

- *American Institute of Architects, 1996

## Role of Laminar Air Flow (Ultraclean Air) in Preventing SSI

- Most studies involve only orthopedic operations
- Lidwell et al:  8,000 total hip and knee replacements                                    _ultraclean air_:    SSI rate 3.4% to 1.6% _antimicrobial prophylaxis (AP):_  SSI rate 					3.4% to 0.8%                                                     _ultraclean air + AP_:  SSI rate 3.4% to 0.7%

## Status of SSI Surveillance 

## CDC Surveillance Systems

| NNIS | DSN | NaSH |
| --- | --- | --- |
| Nosocomial infections in critical care and surgical patients | Bloodstream and vascular access infections in dialysis outpatients | Exposure to bloodborne pathogens; TB skin testing and exposure; Vaccine: history, receipt, and adverse events |

- 1999-2004

- 1970-2004

- 1996-present

## Characteristics of NNIS Hospitals, 2000

- 300 hospitals
- 58% are MAJOR TEACHING
- 10% are Graduate Teaching
- 15% are Limited Teaching
- 16% are Non Affiliated Hospitals
- Bed Size
- Median: 360 beds
- No facilities < 100 beds

## Variables Collected in Surgical Patient Component, NNIS

- Age
- Sex
- ASA score
- Wound class
- Trauma-related
- Type of anesthesia
- Emergency vs elective
- Duration of surgery
- Length of postoperative stay
- Infection site (skin/soft tissue, organ space)
- Pathogen
- Mortality
- Hospital demographics (bed-size, affiliation)

## SSI Risk Index

- From the U.S. National Nosocomial Infections Surveillance (NNIS) system
- American Society of Anesthesiologists (ASA) score
- 1 to 5, from 1=“normal, healthy” to 5=“patient not expected to survive for 24 hours with OR without operation
- Wound Class
- Clean, clean-contaminated, contaminated, dirty
- Duration of surgery

## Surgical Site Infection (SSI) Rates By Risk

**Surgical Site Infection (SSI) Rates By Risk**
** ****Category,  **

**NNIS System, 1986-1999**

**0**

**4**

**8**

**12**

**16**

**1986-90**

**1992**

**1993**

**1994**

**1995**

**1996**

**1997**

**1998**

**1999**

**Years**

**SSIs per 100 operations**

**Low risk**

**Medium**

**low risk**

**Medium**

**high risk**

**High risk**

## SSI Definitions:  Period of Surveillance

- Infection occurs within 30 days after the operative procedure if no implant is left in place or within 1 year if implant is in place and the infection appears to be related to the operative procedure

## Challenges to Surveillance for SSIs

**Challenges to Surveillance for SSIs**

## What Is NHSN?

- 		NNIS
- 		NaSH
- 		DSN

**Integration of CDC’s three**
**patient and healthcare personnel**
**surveillance systems**

## NHSN Premises

- Maintain the goals of predecessor systems
- Minimize data collection and manual data entry burden
- Streamline existing surveillance protocols
- Increase capacity for capturing electronic data (e.g., Laboratory information systems, operating room, pharmacy, clinical, administrative databases)
- Extensible web-based application

**Notes:**
What is OT?  Surgery?  All entities can participate on a limited basis. Hospitals and outpatient dialysis.

## Priority Areas for NHSN Development

- Inclusion of process measures linked to outcomes
- Surgical prophylaxis
- Central line insertion practices
- Completion of HCP Safety Component
- NaSH  NHSN
- Influenza pilot: vaccine coverage and use of antiviral medications

## How do we develop policy? 

## Healthcare Infection Control Practices Advisory Committee (HICPAC) 

**Healthcare Infection Control Practices Advisory Committee (HICPAC) **

## Healthcare Infection Control Practices Advisory CommitteeMISSION

- Advise the US Secretary of Health and the Director of CDC regarding the practice of infection control and strategies for surveillance, prevention and control of antimicrobial resistance, and related adverse events in healthcare settings

## CDC/HICPAC GUIDELINE SCOPE

- TARGET AUDIENCE:
- 	•	clinicians
- 	•	infection control professionals
- 	•	public health officials
- 	•	regulators
- TARGET SETTINGS:
- 	•	Inpatient
- 	•	Outpatient
- 	•	Home care
- 	•	Long term care

## Ranking Scheme for HICPAC Recommendations (2001)

**CATEGORY IA.**  Strongly recommended for all hospitals and strongly supported by well-designed experimental or epidemiologic studies.
**CATEGORY IB.**  Strongly recommended for all hospitals and viewed as effective by experts in the field and a consensus of HICPAC based on strong rationale and suggestive evidence, even though definitive scientific studies may not have been done.
**CATEGORY IC.** Required for implementation, as mandated by federal or state regulation or standard. **CATEGORY II.**  Suggested for implementation in many hospitals. Recommendations may be supported by suggestive clinical or epidemiologic studies, a strong theoretical rationale, or definitive studies applicable to some but not all hospitals.
**NO RECOMMENDATION; UNRESOLVED ISSUE.** Practices for which insufficient evidence or consensus regarding efficacy exists.

## CDC/HICPAC GuidelineRATING SYSTEM

- _CATEGORY_	_EVIDENCE__	_	_PRACTICE_
- 	IA/IB		STRONG		RECOMMENDED
- 	IC			LACKING		REQUIRED BY 							REGULATION
- 	II			GOOD		SUGGESTED
- 	NO REC		INSUFFICIENT	UNRESOLVED
- 				CONTRADICTORY

## Challenges/Issues

- Subject matter experts vs. methodologic experts
- Resources for systematic reviews
- Limited randomized trials
- User needs vs available science (e.g., expansion to non-hospital settings)

## Healthcare Infection Control Practices Advisory CommitteeGUIDELINE FORMAT

- _PART I_:  Provides review and synthesis of 				  available research on guideline topic and 		  established scientific rationale for 				  recommendations
- _PART II_:  Provides summary of practice 				   recommendations
- _PART III_: Provides performance indicators for 			   institutions to monitor success in 				   implementing recommended practices

## Summary

- Prevention of SSI require a multifaceted approach targeting pre-, intra-, and postoperative factors
- Current surveillance systems do collect data on perioperative processes
- Increasing shift of surgical procedures to outpatient settings and decrease in postoperative length of stay complicate surveillance efforts
- Incidence is generally low; so studies would require large sample size
- Some prevention practices (e.g. hand hygiene) would be difficult to study using traditional randomized controlled trial research design

## PREVENTION  IS PRIMARY!

*Protect patients...protect healthcare personnel...*
*promote quality healthcare!*
- Division of Healthcare Quality Promotion

## Division of Healthcare Quality Promotion (DHQP) website

- http://www.cdc.gov/ncidod/hip/default.htm

*To obtain HICPAC guidelines visit the *