Infection control strategies for critically ill patients

This chapter addresses the expectations of  Section 2.1.1 of the CICM Second Part General Exam Syllabus (First Edition), which describes“Principles of infection control including SDD” as core knowledge for the intensive care specialist. This topic has come up in Question 28 from the second paper of 2019, where the college has asked the trainees to comment on the specific infection control processes required to care for patients with things like neutropenic sepsis, Neisseria meningitis and norovirus gastroenteritis. As expected, the trainees were unable to recall the specific recommendations, and  the pass rate was low (21.1%).

What would you have to do to get this sort of information? Well. Conventionally, if one is ever confronted with the question "do I need to isolate the patient with [insert disease here]", one tends to contact the local hospital Infection Control office. The office then quickly Googles the answer. Most often, that search would bring answers from the CDC Infection Control Guidelines Library. Locally, they may also look at the NSW Health  Infectious Diseases page, which has locally important data (eg. notifiable diseases data and Communicable Diseases Weekly Reports). 

So, how does one answer such questions in the future, without having to memorise the entire database of infectious diseases? There really is no solution here. Conceivably, next time CICM could ask about the infection control principles for cholera, Fifth disease and Chikungunya. But, to defend themselves against these dark arts, trainees could at least try to internalise some basic foundational principles of infection control.

Anyway. In terms of infection control principles in a broader sense, such things typically fall into two broad categories:

• The need to protect your staff (and society) from the patient's pathogens, and
• The need to protect the patient from pathogens carried by your staff and the visitors

How much protection is required, depends on:

• How defenceless the patient, or
• How infectious and lethal the pathogen

The basics outlined below mainly came from this CDC document on Transmission-Based Precautions, and from the expanded version of their isolation guidelines

Standard precautions

This is the usual approach to all patients, irrespective of infectious status; all other precautionary steps add on to this basic level of protection. It consists of:

• Hand hygiene before and after all patient contact
• the use of personal protective equipment, which may include gloves, impermeable gowns, plastic aprons, masks, face shields and eye protection
• the safe use and disposal of sharps
• the use of aseptic “non-touch” technique for all invasive procedures, including appropriate use of skin disinfectants
• reprocessing of reusable instruments and equipment
• routine environmental cleaning
• waste management
• respiratory hygiene and cough etiquette
• appropriate handling of linen.

(this is basically cut-and-pasted in an unchanged form from the Victorian health service page, because why change something already said in the best way possible)

Contact precautions

In summary:

• Single rooms
  • Or, cohort patients with the same pathogen in the same room
  • Ensure patients are separated by more than 1m
  • Change protective attire and perform hand hygiene between contact with patients in the same room
• PPE
  • Wear gloves whenever touching the patient’s intact skin
  • Wear a gown whenever anticipating that clothing will have direct contact with the patient
• Limit transport and movement of patients outside of the room
• Use disposable equipment
• Daily cleaning and disinfection of patient rooms, with a focus on frequently-touched surfaces

These are for "for patients with known or suspected infections or evidence of syndromes that represent an increased risk for contact transmission". Such organisms include MRSA, VRE, ESBL gram negatives, etc.

Droplet precautions

In summary, it is everything you would do for a patient on contact precautions, PLUS masks:

• For every time you enter the patient's immediate environment, wearr a mask
• If transport or movement in any healthcare setting is necessary, instruct patient to wear a mask (in which case, you don't have to)

This is for "patients known or suspected to be infected with pathogens transmitted by respiratory droplets (i.e., large-particle droplets >5µ in size) that are generated by a patient who is coughing, sneezing or talking".

Airborne pathogen precautions

This is the same as droplet precautions, EXCEPT:

• The mask you wear is a N95 or higher level respirator

Also:

• Use a negative pressure room
• The room has to have 6-12 air changes per hour
• The exhaust air must go directly outside, i.e. not back into the hospital
• Restrict susceptible healthcare personnel from entering the room ("susceptible" means not immunised, pregnant, immunosuppressed, etc

This is for "patients known or suspected to be infected with infectious agents transmitted person-to-person by the airborne route"

Reverse barrier precautions

For patients who are sufficiently immunocompromised to require a protected environment, that environment should look like this:

• Filter all incoming air using high efficiency particulate (HEPA) filters
• Direct room airflow with the air supply on one side of the room that moves air across the patient bed and out through an exhaust on the opposite side of the room  
• Positive air pressure in room relative to the corridor 
• Use an anteroom
• At least 12 air changes per hour
• Lower the dust levels:
  • Avoid carpeting in hallways and patient room
  • Prohibit plants
  • Use smooth, nonporous surfaces and finishes that can be scrubbed
• Visitors and staff should use contact and airborne precautions