Basics of Electrocardiography for Technicians (Class note)

What is an ECG?

Recording of the electrical activity heart.

ØGraph of voltage versus time 

Basics

ECG graph:

Ø1 mm Small squares

Ø5 mm Large squares

Paper Speed:

Ø25 mm/sec standard

Voltage Calibration:

Ø10 mm/mV standard

ECG Leads

Leads are electrodes which measure the potential difference between:

1.Two different points on the body (bipolar leads)

2.One point on the body and a virtual reference point with zero electrical potential, located in the centre of the heart (unipolar leads)

Einthoven's triangle

Precordial Leads

Electrode name	Electrode placement
RA	On the right arm, avoiding thick muscle.
LA	On the left arm, avoiding thick muscle.
RL	On the right leg, lateral calf muscle.
LL	On the left leg, lateral calf muscle.
V1	In the fourth intercostal space (between ribs 4 and 5) just to the right of the sternum (breastbone).
V2	In the fourth intercostal space (between ribs 4 and 5) just to the left of the sternum.
V3	Between leads V2 and V4.
V4	5th Intercostal space at the midclavicular line
V5	Anterior axillary line at the same level as V4
V6	Midaxillary line at the same level as V4 and V5

Arrangement of Leads on the ECG

Normal standardization

—1 mV=10 mm

—Will result in perfect right angles at each corner

Overdamping and Underdamping

—Overdamping: When the pressure of the stylus is too firm on the paper so that it’s movements are retarded – deflection fractionally wider and diminished amplitude

—

—Unerdamping: When the writing stylus is not pressed firmly enough against the paper - sharp spikes at the corners

Specific cardiac abnormalities

—dextrocardiaà right & left arm electrodes should be reversed

  pre-cordial leads should be recorded from V1R(V2) to V6

Artefacts on ECG

Distorted signals caused by secondary internal or external sources, such as muscle movement or interference from an   electrical device.

—ECG tracing is affected by patient’s motion.

—

—Rhythmic motions (shivering or tremors) can create the illusion of arrhythmia. 

—

—May lead to:

ØAltered diagnosis, treatment, outcome of therapy and legal liabilities

Reducing Artefacts during an ECG

Patient Positioning

—Supine or semi-Fowler’s position.

ØIf patient can’t tolerate lying flat, do the ECG in a more upright position.

—Instruct patient to place arms down by his side and to relax the shoulders.

—Patient’s legs should be uncrossed.

—

—Place electrical devices, such as cell phones, away from the patient as they may interfere with the machine.

Skin Preparation

—Dry the skin if it’s moist or diaphoretic.

—

—Shave any hair that interferes with electrode placement.

Øensures a better electrode contact with the skin.

—

—Rub an alcohol prep pad or benzoin tincture on the skin to remove any oils and help with electrode adhesion.

Electrode Application

—Check the electrodes to make sure the gel is still moist.

—

—Do not place the electrodes over bones.

—

—Do not place the electrodes over areas where there is a lot of muscle movement.

Interpretation of an ECG

—Heart Rate

—Rhythm

—Axis

—Wave morphology

—Intervals and segments analysis

—Specific changes (If any)

Infection control in ICU

Class note for Diploma Critical Care technology

An infection control programme puts together various practices which, when used appropriately, restrict the spread of infection. A breach in infection control practices facilitates transmission of infection from

•  patients to health care workers
• other patients
•  attendants

It is therefore important for all health care providers to adhere to the infection control guidelines strictly.

Epidemiology

The major Hospital Acquired Infections include catheter-associated urinary tract infections (CAUTI; 40%, ventilator-associated and healthcare-associated pneumonia (25%), catheter-associated bloodstream infections (CABSI; 10%), and surgical site infections according to CDC (1).

UTI: Urinary tract infection; HCAP: Healthcare-associated pneumonia; CABSI: Catheter-associated bloodstream infection.

Pathogenesis

Patients who are at a higher risk of developing Hospital Acquired infections (2)

• Age more than 70 years
• Shock
• Major trauma
• Acute renal failure
• Coma
• Prior antibiotics
• Mechanical ventilation
• Drugs affecting the immune system (steroids, chemotherapy)
• Indwelling catheters
• Prolonged ICU stay (>3 days)

Components of the infection control programme

• basic measures for infection control, i.e. standard and additional precautions
• education and training of health care workers
• protection of health care workers, e.g. immunization
•  identification of hazards and minimizing risks
•  routine practices essential to infection control such as aseptic techniques, use of single use devices, reprocessing of instruments and equipment, antibiotic usage, management of blood/body fluid exposure, handling and use of blood and blood products, sound management of medical waste
•  effective work practices and procedures, such as environmental management practices including management of hospital/clinical waste, support services (e.g., food, linen), use of therapeutic devices
•  surveillance
•  incident monitoring
• outbreak investigation
•  research

Infection Control Practices

Infection control practices can be grouped in two categories

• ·         Standard precautions
• ·         Additional (transmission-based) precautions

“Standard precautions” require that health care workers assume that the blood and body substances of all patients are potential sources of infection, regardless of the diagnosis, or presumed infectious status. 

Components of Standard Precautions include the following:

• 1.      hand washing and antisepsis (hand hygiene)
• 2.      use of personal protective equipment when handling blood, body substances, excretions and secretions
• 3.      appropriate handling of patient care equipment and soiled linen
• 4.      prevention of needlestick/sharp injuries
• 5.      appropriate handling of waste

 Hand washing and antisepsis (hand hygiene)

 When and why – follow World Health Organizations (WHO′s) five moments for hand hygiene

• ·         Before touching a patient – to protect the patient from harmful germs carried on your hands
• ·         Before aseptic procedures – to protect the patient against harmful germs, including the patient's own germs
• ·         After body fluid exposure/risk – to protect yourself and the health care environment from the harmful patient's germs
• ·         After touching the patien– to protect yourself and the health care environment from the harmful patient's germs
• ·         After touching the patient's surrounding– to protect yourself and the health care environment from the harmful patient's germs.

How?

·         Wash hands with soap and water when they are soiled or visibly dirty with blood or other body fluids (IB). Wet your hands, apply soap and then scrub them vigorously for at least 15 s. Cover all surfaces of the hands and fingers, wash with water and then dry thoroughly using a disposable towel

·         Use an alcohol-based hand rub (IA) e.g. 0.5% chlorhexidine with 70% w/v ethanol, if hands are not visibly dirty. A combination of chlorhexidine and alcohol is ideal as they cover Gram-positive and Gram-negative organisms, viruses, mycobacteria and fungi. Chlorhexidine also has residual activity.

• ·         During surgical hand preparation, all hand jewelries (e.g. rings, watches and bracelets) must be removed
• ·         Finger nails should be trimmed to <0.5 cm (2A) with no nail polish or artificial nails
• ·         Avoid wearing long sleeves, ties should be tucked in, house coats are discouraged and wearing scrubs is encouraged

Use of personal protective equipment when handling blood, body substances, excretions and secretions

Gloves

Sterile gloves should be worn after hand hygiene procedure while touching mucous membrane and non-intact skin and performing sterile procedures e.g. arterial, central line and Foley catheter insertion.

• 
  
•       Clean, non-sterile gloves are safe for touching blood, other body fluids, contaminated items and any other potentially infectious materials
•       Change gloves between tasks and procedures in the same patient especially when moving from a contaminated body area to a clean body area
•        Never wear the same pair of gloves for the care of more than one patient
•        Remove gloves after caring for a patient
•        Practice hand hygiene whenever gloves are removed.

Gown

•     Wear a gown to prevent soiling of clothing and skin during procedures that are likely to generate splashes of blood, body fluids, secretions or excretions
•       The sterile gown is required only for aseptic procedures and for the rest, a clean, non-sterile gown is sufficient
•        Remove the soiled gown as soon as possible, with care to avoid contamination.

Mask, eye protection/face shield

•      Wear a mask and adequate eye protection (eyeglasses are not enough), or a face shield to protect mucous membranes of the eyes, nose and mouth during procedures and patient care activities that are likely to generate splashes/sprays of blood and body fluids, etc.
•       Patients, relatives and health care workers (HCWs) presenting with respiratory symptoms should also use masks (e.g. cough).

Shoe and head coverings

•      Wear caps and boots/shoe covers where there is a likelihood the patient’s blood, body fluids,   secretions or excretions may splash, spill or leak onto the hair or shoes.
•          Launder caps and shoe covers appropriately if they are reusable, according to the hospital guidelines.
•          Do not reuse disposable caps/shoe covers.
•          Clean and disinfect reusable boots.

Appropriate handling of patient care equipment and soiled linen

•     Used patient-care equipment soiled with blood, body fluids, secretions, or excretions should be handled carefully to prevent skin and mucous membrane exposures, contamination of clothing and transfer of microorganisms to HCWs, other patients or the environment
•        Ensure that reusable equipment is not used for the care of another patient until it has been cleaned and sterilized appropriately
•        Ensure that single use items and sharps are discarded properly 

Prevention of needlestick/sharp injuries

•       Place used disposable syringes and needles, scalpel blades and other sharp items in a puncture-    resistant container with a lid that closes and is located close to the area in which the item is used.
•           Take extra care when cleaning sharp reusable instruments or equipment.
•            Never recap or bend needles.
•          Sharps must be appropriately disinfected and/or destroyed as per the national standards or guidelines.

Appropriate handling of waste

Uncollected, long stored waste or waste routing within the premises must be avoided. A sound waste management system needs to be developed and closely monitored.

Additional (transmission-based) precautions

Additional precautions are needed for diseases transmitted by air, droplets and contact. Additional (transmission-based) precautions are taken while ensuring standard precautions are maintained. They include:

• ·         Airborne precautions
• ·         Droplet precautions
• ·         Contact precautions

Airborne precautions

Airborne transmission occurs when droplet nuclei (evaporated droplets) <5 micron in size are disseminated in the air>nuclei (evaporated droplets) <5 micron in size are disseminated in air. These particles can remain suspended in the air for long periods of time, especially when bound on dust particles.

•       Disease-causing microorganisms may be suspended in the air as small particles, aerosols, or dust and remain infective over time and distance, for example, Mycobacterium tuberculosis (pulmonary/laryngeal), varicella zoster virus (chickenpox), herpes zoster (shingles), rubella virus and measles
•       Isolate with negative-pressure ventilation
•       Respiratory protection must be employed when entering the isolation room
•     Use the disposable N-95 respirator mask, which fits tightly around the nose and mouth to protect against both large and small droplets. This should be worn by all persons entering the room, including visitors 

Droplet precautions

•     Microorganisms are also transmitted by droplets (large particles >5 μm in size) generated during coughing, sneezing and talking, or a short-distance travelling, for example, influenza virus, Bordetella pertussis,Hemophilus influenzae (meningitis, pneumonia), Neisseria meningitidis (meningitis, pneumonia and bacteremia), Mycoplasma pneumoniae, Severe acute respiratory syndrome-associated coronavirus, Group A Streptococcus, adenovirus and rhinovirus.
•       Isolation is required
•      Respiratory protection must be employed when entering the isolation room or within 6-10 ft of the patient. Use the disposable N-95 respirator mask, which fits tightly around the nose and mouth to protect against both large and small droplets. This should be worn by all persons entering the room, including visitors
•       Limit transport of the patient

Contact precautions

Infections can be spread by usual direct or indirect contact with an infected person, the surfaces or patient care items in the room, for example, parainfluenza virus infection, respiratory syncytial virus infection, varicella (chickenpox), herpes zoster, hepatitis A and rotavirus infections.

•        Isolation is required
•        Non-critical patient-care equipment should preferably be of single use. If unavoidable, then clean and disinfect them adequately before using to another patient
•       Limit transport of the patient 

Cohorting

For infection control purposes, if single rooms are not available, or if there is a shortage of single rooms, patients infected or colonized by the same organism can be cohorted (sharing of room/s). When cohorting is used during outbreaks these room/s should be in a well-defined area (a designated room or designated ward), which can be clearly segregated from other patient care areas in the health care facility used for non-infected/colonized patients.

Patient Bathing and Environmental Precautions

Chlorhexidine gluconate when used for daily bathing reduces the incidence of MRSA and VRE by 23% (1). Environmental cleaning, disinfection, and sterilization are also critical infection control measures.

Disinfection is a process that eliminates non-spore forming pathogenic microorganisms from inanimate objects. Sterilization, a complete microbial elimination, can be accomplished with physical or chemical processes.

Use specific strategies focused on prevention of specific nosocomial infections

In addition to the standard and transmission-based precautions, there are several strategies focused on prevention of specific nosocomial infections in critically ill patients. Of these, ventilator-associated pneumonia (VAP), catheter-related bloodstream infection (CRBSI) and urinary tract infection (UTI) are the most important.

Strategies to reduce VAP

·         Oral intubation (unless contraindicated)

·         Head of patient’s bed raised between 30-45 degree (unless contraindicated)

·         Scheduled drainage from ventilator circuits

·         Continuous subglottic suctioning

·         Avoid gastric distension

·         Oral care with an antiseptic solution (i.e. chlorhexidine)

·         Daily assessment for readiness to wean and use of weaning protocols

·         Maintain adequate pressure cuff at least 20 cm of water

·         Meticulous hand hygiene

·         Proton pump inhibitors/ H2 blockers in intubated patients

Strategies to reduce CRBSI

Facility policies	Central line insertion	Care and use
Infection control and surveillance to determine infection rates and failures.	Site, catheter, and insertion technique with lowest complication.	Cleansing of port with chlorhexidine is superior to iodophor (10% povidine-iodine).
Education and assessment of adherence to guidelines for quality assurance/improvement.	Aseptic technique during catheter placement and care.	Replacement of wet soiled or dislodged central line dressing.
Provide checklists to ensure infection preventive practices.	Catheter site disinfection with 0.5% chlorhexidine.	Daily assessment and prompt removal of unnecessary catheter.
Designated, trained personnel for insertion and maintenance	Maximal barrier precautions (gloves, gowns and facemask).	Antiseptic/antibiotic impregnated CVCs and Chlorhexidine-impregnated sponge dressings can be considered if the rate of infection is not decreasing.
Meticulous hand hygiene for all healthcare workers.	Use of sterile, semi permeable transparent dressing.

Strategies to reduce UTI

·         Daily surveillance regarding further need of catheter

·         Catheterization only when necessary

·         Maintenance of free urine flow

·         Use of aseptic techniques

·         Proper securing of catheter on body

·         Maintenance of closed sterile drainage tubes

·         Aseptic techniques for obtaining urine samples

·         Meticulous Hand hygiene

·         Avoidance of prophylactic antibiotics and regular urine culture

Prevention of Surgical-Site Infection

Pre-operative Core Measures	Perioperative Core Measures
Administer appropriate antimicrobial prophylaxis within 1 hour prior to incision (2 hour for vancomycin and fluoroquinolones)	Maintain normothermia early postoperative
Screen and treat remote infections before surgery	Keep operating room doors closed during surgery
If needed, remove hair by clipping or depilatory agents instead of sharp razor	Perioperative Supplemental Measures
Skin preparation with appropriate antiseptic agents	Repeat antibiotic dose at the 3 hr interval in procedures with duration >3hrs
Nasal screen and decolonize Staphylococcus aureus carriers undergoing elective procedures	Dose Adjustment of antimicrobial prophylaxis for obese patients (BMI >30)
Screen preoperative blood glucose levels and maintain glucose control in first 2 days patients undergoing select elective procedures	Use FiO2 at least 50% in during surgery and immediately post op period in select procedure

Architecture and layout of the ICU

•     The unit may be situated close to the operating theater and emergency department for easy       accessibility, but should be away from the main ward areas
•        Central air-conditioning systems are designed in such a way that recirculated air must pass through     appropriate filters
•         It is recommended that all air should be filtered to 99% efficiency down to 5 μm
•       Suitable and safe air quality must be maintained at all times. Air movement should always be from      clean to dirty areas
•       It is recommended to have a minimum of six total air changes per room per hour, with two air  changes per hour composed of outside air (3)
•        Isolation facility should be with both negative- and positive-pressure ventilations
•        Clearly demarcated routes of traffic flow through the ICU are required
•        Adequate space around beds is ideally 2.5-3 m
•         Electricity, air, vacuum outlets/connections should not hamper access around the bed
•        Adequate number of washbasins should be installed
•        Alcohol gel dispensers are required at the ICU entry, exits, every bed space and every workstation 
•        There should be separate medication preparation area
•        There should be separate areas for clean storage and soiled and waste storage and disposal
•        Adequate toilet facilities should be provided 

References:

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1	[Online].; 2016. Available from: http://www.esciencecentral.org/ebooks/bedside-critical-care-guide/icu-infection-control-and-preventive-measures.php.
2	[Online].; 2016. Available from: http://www.cdc.gov/hicpac/pdf/isolation/Isolation2007.pdf.
3	[Online]. [cited 2016 July 08. Available from: http://www.cdc.gov/hicpac/pdf/guidelines/eic_in_HCF_03.pdf.