Acute and Chronic Sinusitis

Objectives
•    Be knowledgeable of the causes of and risk factors associated with sinusitis
•    Differentiate acute from chronic sinusitis
•    Evaluate patients by history, physical exam, appropriate laboratory and imaging studies, and when indicated screen patients for allergy
•    Prescribe appropriate medication regimens for acute and chronic sinusitis
•    Know of the relationships between upper airway (rhinosinusitis) and lower airway disease (asthma)




Rhinosinusitis May be Better Term Because
•    Allergic or nonallergic rhinitis nearly always precedes sinusitis
•    Sinusitis without rhinitis is rare
•    Nasal discharge and congestion are prominent symptoms of sinusitis
•    Nasal mucosa and sinus mucosa are similar and are contiguous



Development of Sinuses
•    Maxillary and ethmoid sinuses present at birth
•    Frontal sinus developed by age 5 or 6
•    Sphenoid sinus last to develop, 8-10


Physiologic Importance of Sinuses
•    Provide mucus to upper airways
–    Lubrication
–    Vehicle for trapping viruses, bacteria, foreign material for removal
•    Give characteristics to  voice
•    Lessen skull weight
•    Involved with olfaction


Sinusitis
•        4 paranasal sinuses, each lined with pseudostratified     ciliated columnar epithelium and goblet cells
–    Frontal 
–    Maxillary
–    Ethmoid
–    Sphenoid

 Ostiomeatal Complex
•    Ostiomeatal complex is that area under the middle meatus (airspace) into which the anterior ethmoid, frontal and maxillary sinuses drain
•    Posterior ethmoids drain into the upper meatus
•    Ostiomeatal complex is the functional relationship between the space and the ostia that drain into it


Viral Rhinosinusitis
•    Most upper respiratory infections are viral
•    Short lived, last less than 10 days
•    Sinus mucosa as well as nasal mucosa is involved
•    Most will clear without antibiotics
•    Treatment: decongestants, nasal lavage, rest, fluids


Classification of Bacterial Sinusitis
•    Acute bacterial sinusitis- infection  lasting 4 weeks, symptoms resolve completely (children 30 days)
•    Subacute bacterial sinusitis- infection lasting between 4 to 12 weeks,  yet resolves completely (children 30-90 days)
•    Chronic sinusitis- symptoms lasting more than 12 weeks (children >90 days)
•    Some guidelines add treatment failure + a positive imaging study


Recurrent Acute Bacterial Sinusitis
•    Episodes lasting fewer than 4 weeks and separated by intervals of at least 10 days during which the patient is totally asymptomatic
•    3 episodes in 6 months or 4/year


Acute Sinusitis Imposed on
Chronic Sinusitis
•    Patients with chronic, low grade symptoms experience increase  in mucous flow, change in viscosity or color, or secretions
•    Treated
•    New symptoms resolve but chronic symptoms continue


Differentiating Sinusitis from Rhinitis
Sinusitis
Nasal congestion
Purulent rhinorrhea
Postnasal drip
Headache
Facial pain
Anosmia
Cough, fever


Rhinitis
Nasal congestion
Rhinorrhea clear
Runny nose
Itching, red eyes
Nasal crease
Seasonal symptoms



Road to Bacterial Sinus Infections
•    Obstruction of the various ostia
•    Impairment in ciliary function
•    Increased viscosity of secretions
•    Impaired immunity
•    Mucus accumulates
•    Decrease in oxygenation in the sinuses
•    Bacterial overgrowth



Pathogenesis of Nasal Obstruction
•    Viral upper respiratory infections
–    Daycare centers
•    Allergic and nonallergic stimuli
•    Immunodeficiency disorders
–    Immunoglobulin deficiency (IgA, IgG)
•    Anatomic changes
–    Deviated septum, concha bullosa, polyps



Allergic Stimuli Causing Rhinosinusitis
•    Pollens
–    Tree, grass, weeds
•    House dust mite
•    Animal danders
–    Cat, dog, mice, gerbil, other animals with fur
•    Molds
•    Allergic foods and beverages


Nonallergic Stimuli Causing Rhinosinusitis
•    Tobacco smoke
•    Perfumes
•    Cleaning solutions
•    Potpourri
•    Burning candles
•    Cosmetics
•    Car exhaust, diesel fumes
•    Hair spray
•    Cold air
•    Dry air
•    Changes in barometric pressure
•    Auto exhaust
•    Gas, diesel fuel
•    Nonallergic foods
•    Nonallergic beverages


Causes of Ciliary Dysfunction
•    Immotile cilia syndrome
•    Prolonged exposure to cigarette smoke
•    Common cold viruses causing URI
•    Increased viscosity of mucus
•    Medications
–    First generation antihistamines (non sedating do not affect)
–    Anticholinergics
–    Aspirin
–    Anesthetic agents
–    Benzodiazepines


Diseases Slowing Ciliary Function
•    Allergic and nonallergic rhinitis
•    Rhinosinusitis
•    Aging rhinitis
•    Cystic fibrosis
•    Any disease causing obstruction, crusting of the mucosa


Causes of Mechanical Obstruction
•    Deviated nasal septum
•    Concha bullosa
•    Foreign body
•    Nasal polyps
•    Congenital atresia
•    Lymphoid hyperplasia
•    Nasal structural changes found in Downs syndrome



Vasculitides, Autoimmune and Granulomatous Diseases 
•    Churg-Strauss vasculitis
•    Systemic lupus erythematosis
•    Sjogren’s syndrome
•    Sarcoidosis
•    Wegener granulomatosis


Other Predisposing Conditions 
•    Physical trauma
•    Scuba diving
•    Foreign body
•    Cleft palate
•    Dental disorders
•    Any patient with chronic fatigue, fever, general malaise/aching or headaches should be evaluated for sinusitis


Acute Bacterial Sinusitis
•     Usually begins with viral upper respiratory illness
•    Symptoms initially improve, but then …
•    Symptoms become persistent or severe
•    Persistent… 10-14 days but fewer than 4 weeks
•    Severe…temperature of 102°, purulent nasal discharge for 3-4 days, child appears ill
•    Disease clears with appropriate medical treatment


Physical Findings
•    Mucopurulent nasal discharge
–    Highest positive predictive value
•    Swelling of nasal mucosa 
•    Mild erythema
•    Facial pain (unusual in children)
•    Periorbital swelling


Objectives of Treatment of Acute Bacterial Sinusitis
•    Decrease time of recovery
•    Prevent chronic disease
•    Decrease exacerbations of asthma or other secondary diseases
•    Do so in a cost-effective way!


Treatment of Acute Sinusitis
•    Antihistamines recommended if allergy present
–    Oral or topical
•    Decongestants
–    Oral or topical
•    Antibiotic when indicated (bacteria)
•    Nasal irrigation
•    Guaifenesin 200-400 mg q4-6 hrs
•    Hydration

Decongestants
•    Topical nasal sprays (limit use to 3-7 days)
–    Phenylephrine
–    Oxymetazoline
–    Naphthazoline
–    Tetrahydrozoline
–    Zylometazoline
•    Topical nasal spray (unlimited daily use)
–    Ipatropium
•    Oral
–    Pseudoephedrine 30-60 mg
–    Phenylephrine 2-4 times/day

Treatment of Acute, 
Uncomplicated Sinusitis

Antibiotic may not be indicated
Many are viral
Benefit of antibiotics are only moderate
Weigh factors of cost, side effects, antibiotic resistance, and antibiotic reactions

Antibiotics for Acute Bacterial Sinusitis
•    Amoxicillin 500 mg tid for 10-14 days
–    First line choice in most areas
–    Local differences in antibiotic resistance occur
•    Where beta-lactanase resistance is an issue
–     Amoxicillin/clavulanate
–    Cefuroxime
–    Cefpodoxime
–    Cefprozil



Additional Antibiotics for Acute 
Bacterial Sinusitis
•    Amoxicillin should be considered because of its efficacy, low cost, side-effect profile, and narrow spectrum (45-90 mg/kg/d in children; 500 mg tid or qid in adults for 10 to 14 days)
•    If penicillin-allergic clarithromycin  or azithromycin
•    Erythromycin does not provide adequate coverage
•    Trimethoprim/suflamethoxazole and erythro/sulfisoxazole have significant pneumococcal resistance


Nasal Irrigation
•    Commercial buffered sprays
•    Bulb syringe
–    1/4 tsp of salt to 7 ounces water
•    Waterpik with lavage tip
–    1 tsp salt to reservoir
•    Disposable enema bucket
–    2 tsp salt, 1 tsp soda per quart of water

•    Washes away irritants
•    Moistens the dry nose
•    Waterpik with nasal irrigator
•    Ceramic irrigators
•    Enema bucket with normal saline and soda
–    “Hose-in-the-nose”-- $2.50


•    With enema bucket/hose….
–    Add 2 teaspoons of salt and 1 tsp of baking soda to a quart of warm water
–    Over tub, sink, or in shower lean over, head tilted slightly downward and to side place hose in upper nostril (fluid may return from either nostril or through mouth) run in 1/2 solution. Turn head to opposite side and repeat process.
–    Use once, twice daily or as often as needed


When Medical Therapy for Acute Bacterial Sinusitis Fails…
•    Assess for chronic causes
–    Identify allergic and nonallergic triggers
•    Allergy testing, nasal smears for eosinophilia
–    Consider other medical conditions associated with sinusitis
–    Rhinolaryngoscopy
–    Imaging studies
        Sinus x-rays
        CT scanning (limited, coronal views)


Sinus Transillumination
•    Helpful in older children and adults
•    Normal transillumination decreases chance of pus in the sinus
•    No light reflex suggests mucopurulent material or thickening of nasal mucosa
•    Inexpensive screening tool

•    Have patient sit at your eye level in darkened room (the darker the better)
•    Let eyes get accustomed to dark
•    Place bright light (transilluminator) over inferior orbital ridge to look at maxillary sinuses, under superior orbital rim for frontal sinuses
•    Look at palate for presence/absence of transilluminated light


Rhinoscopy Aids in Diagnosing
•    Nasal polyps
•    Septal deviation
•    Concha bullosa
•    Eustachian tube dysfunction
•    Causes of  hoarseness
•    Adenoid hyperplasia
•    Tumors

MRI Imaging
•    Not used for imaging suspected acute sinusitis
•    Suspected fungal sinusitis
•    Suspected tumors


Bacteria Involved in Acute 
Bacterial Sinusitis
•    Streptococcus pneumoniae     30%
•    Haemophilus influenza        20%
•    Moraxella catarrhalis        20%
•    Sterile                30%



Rational for Starting Rx with Amoxicillin
•    In the absence of risk factors, i.e. attendance in daycare center, recent antibiotics, age younger than 2…
•    80% of patients will respond to amoxicillin
•    Give Rx for 5 days with a refill -- if responding treat for 10 to 14 days, if not, switch to another


Reasons to Use Alternative Antibiotics
•    No response to amoxicillin within 3-5 days
•    Recent treatment with amoxicillin for other causes
•    Symptoms present for more than 30 days
•    Recurrent sinus infections


Secondary Antibiotics for Acute Sinusitis
•    Cefdinir (Omnicef)
•    Cefuroxime (Ceftin)
•    Cephpodoxime (Vantin)
•    Azithromycin
•    Clarithromycin



Optimal Duration of Antibiotics

Give antibiotic until patient free of symptoms then add 7 days



Chronic Sinusitis
•    Symptoms present longer than 8 weeks or 4/year in adults or 12 weeks or 6 episodes/year in children
•    Eosinophilic inflammation or chronic infection
•    Associated with positive CT scans
•    Poor (if any) response to antibiotics


Quality-of-Life Issues
•    Fatigue
•    Concentration
•    Nuisance
•    Sleep disturbance
•    Emotional well being
•    Social interactions

•    Missing school/work
•    Halitosis     
•    Decreased production
•    Impaired studying
•    Sniffing/snorting
•    Blowing nose



Sx of Chronic Sinusitis
•    Nasal discharge
•    Nasal congestion
•    Headache
•    Facial pain or pressure
•    Olfactory disturbance
•    Fever and halitosis
•    Cough (worse when lying down)



Conditions Causing Chronic Sinusitis
•    Allergic and nonallergic rhinitis
•    Uncorrected anatomic conditions
•    Ciliary dyskinesia
•    Cystic fibrosis
•    Tumors
•    Immunodeficiency disorders
–    IgA, IgM
•    Granulomatous diseases



Evaluation of Chronic Sinusitis
•    CT or MRI scanning
–    Anatomic defects, tumors, fungi
•    Allergy testing
–    Inhalants, fungi, foods
•    Sinus aspiration for cultures
–    Bacterial
–    Fungal
•    Immunoglobulins



Treatment of Chronic Sinusitis
•    Nasal steroid spray
•    Guafenesin
•    Decongestants
•    Steam inhalation
•    Nasal  irrigation
•    Antibiotics with exacerbations



Bacteria Involved in Chronic Sinusitis Role of Viruses is Unknown
•    Streptococcus pneumoniae  
•    Haemophilus influenza     
•    Moraxella catarrhalis
•    Staph aureus     
•    Coagulase negative staphylococcus
•    Anerobic bacteria

             

Transition of Bacteria Rom Acute to Chronic Sinusitis
•    In one study, while initial aspirates showed strep pneumoniae, H. influenzae, and M catarrhalis, subsequent cultures showed Porphyromonas, Peptostreptococcus, and aerobic organisms found to be increasingly resistant to antibiotics
Sinus Aspiration and Culture
•    Correlation of routine nasal culture and sinus culture are poor
•    Endoscopically guided aspiration of cultures from medial meatus do correlate with sinus culture

 
Recommendations Made for Antibiotic Prophylaxis in ABS
•    Has not been evaluated as has its use in otitis media
•    Increasing evidence of antibiotic resistance is an issue
•    May be tried in chronic or recurrent disease


Complications of Sinusitis
•    Orbital
–    Diplopia, proptosis
–    Periorbital erythema, swelling
•    Bone
–    Periosteal abscesses
•    Brain
–    Intracranial abscesses causing neurologic symptoms



The Sinusitis-Asthma Connection
•    Mechanism is not understood
•    Evidence is compelling
•    Failure to control upper airway inflammation leads to suboptimal asthma control
•    Correcting the rhinosinusitis results in better asthma control


Indications for Referral 
•    Allergy testing, possible immunotherapy
•    Sinus aspiration for bacterial culture
•    Surgical intervention
–    Correct obstructive process
–    Drain sinus abscesses
–    Consideration to remove nasal polyps


Indications for Hospitalization
•    Acutely ill child or adult with high fever, severe head pain
•    Suspected sphenoid sinusitis
•    Anytime complications of eye, bone or intracranial structures are present


The Recommendations
    The recommendations cited are those proposed by a task force of the American Academy of Pediatrics in consultation with other groups regarding the evaluation, diagnosis, and treatment of patients aged 1-21 years with sinus disease…expert opinion was used when insufficient data could be found.

Recommendation 1
The diagnosis of acute bacterial sinusitis is based on clinical criteria with patients presenting with URI symptoms that are either persistent or severe.

Recommendation 2a
•    Imaging studies are not necessary to confirm a diagnosis of clinical sinusitis in children younger than 6 years (older than age 6 years is controversial)
•    Children with persistent symptoms (>10 days, < 30 days) predicted abnormal radiographs 80% of the time
•    Children < 6 symptoms predicted 88% of the time
•    Normal x-ray suggests ABS is not present
 

Recommendation 2b
•    CT scans of the paranasal sinuses should be reserved for:
–    Patients in whom surgery is being considered as a management strategy
–    Patients who do not respond to medical regimes which include adequate antibiotic use
–    Assisting in diagnosis of anatomical changes interfering with airflow or drainage



Recommendations for CT Scans
•    Patients presenting with complications of sinusitis
–    Neurologic symptoms, diplopia, periorbital or facial swelling with or without erythema
•    Patients with sinus symptoms accompanied by severe, boring, mid-head pain
–    Rule out sphenoid sinusitis


Recommendation 3
•    Antibiotics are recommended for the management of acute bacterial sinusitis to achieve a more rapid clinical cure
•    Patients must meet requirements of persistent or severe disease
•    Response improved with doses >Minimal Inhibition Concentration



No EB Recommendations Found for Use of Adjunctive Therapy in ABS, May be Helpful
•    Nasal saline irrigation
•    Oral decongestants
•    Oral or nasal antihistamines
•    Topical decongestants
•    Mucolytic agents
•    Topical steroids



Summary
•    Acute and chronic sinusitis is one of the most common diseases treated in family practice
•    It is important to treat sinusitis aggressively to prevent chronic symptoms or development of serious complications
•    The underlying causes of chronic sinus disease should be sought out and corrected


Harold H. Hedges, III, M.D.
Private Practice
Little Rock Family Practice Clinic
Little Rock, Arkansas

and

Susan P. Pollart, M.D.
Associate Professor of Family Medicine
University of Virginia Health System
Charlottesville, Virginia

Classification Of Carbohydrates

Carbohydrates, also known as saccharides, are classified according to the number of single carbohydrate molecules in each chemical structure. Carbohydrate compounds having just one carbohydrate molecule are called monosaccharides; compounds with two carbohydrate molecules are called dissarcharides; and those compounds containing more than two carbohydrate molecules are named polysaccharides. All carbohydrates either are monosaccharides or can be hydrolyzed (broken down) into two or more monosaccharides.

For further understanding of these different classifications of carbohydrates, the monosaccharides and disaccharides can be grouped together and compared with the polysaccharides. This can be done because monosaccharides and disaccharides have certain things in common.

For one, they are both water soluble. In addition, they have a sweet taste and a crystalline structure. The monosaccharides and disaccharides are called sugars and all share the suffix, -ose, meaning sugar.

Polysaccharides, in contrast to mono- and disaccharides, are insoluble in water, do not taste sweet and do not form crystals. Also, they do not share a suffix and have no group name (such as sugars, in the case of mono-arid disaccharides). They are sometimes called starches, but this is technically incorrect because there are many other classifications of polysaccharides besides starches (cellulose and glycogen being two and dextrin being another).

2.1 Monosaccharides

These are the only sugars that can be absorbed and utilized by the body. Disaccharides and polysaccharides must be ultimately broken down into monosaccharides in the digestive process known ashydrolysis. Only then can they be utilized by the body. Three monosaccharides are particularly important in the study of nutritional science: glucose, fructose and galactose.

2.2 Glucose (also known as dextrose or grape sugar)

This monosaccharide is the most important carbohydrate in human nutrition because it is the one that the body fuses directly to supply its energy needs. Glucose is formed from the hydrolysis of di- and polysaccharides, including starch, dextrin, maltose, sucrose and lactose; from the monosaccharide fructose largely during absorption; and from both fructose and galactose in the liver during metabolism.

Glucose is the carbohydrate found in the bloodstream, and it provides an immediate source of energy for the body's cells and tissues. Glucose is also formed when stored body carbohydrate (glycogen) is broken down for use.

In the plant world, glucose is widely distributed. It is found in all plants and in the sap of trees. Fruits and vegetables are wholesome food sources of glucose. It is also present in such unwholesome (to humans) substances as molasses, honey and corn syrup.

2.3 Fructose (also known as levulose or fruit sugar)

Fructose, a monosaccharide, is very similar to another monosaccharide, galactose. These two simple sugars share the same chemical formula; however, the arrangements of their chemical groups along the chemical chain differ. Fructose is the sweetest of all the sugars and is found in fruits, vegetables and the nectar of flowers, as well as in the unwholesome (to humans) sweeteners, molasses and honey. In humans, fructose is produced during the hydrolysis of the disaccharide, sucrose.

2.4 Galactose

Galactose differs from the other simple sugars, glucose and fructose, in that it does not occur free in nature. It is produced in the body in the digestion of lactose, a disaccharide.

2.5 Disaccharides

Disaccharides, on hydrolysis, yield two monosaccharide molecules. Three particular disaccharides warrant discussion in a lesson on nutritional science: sucrose, maltose and lactose.

2.6 Sucrose

The disaccharide, sucrose, consists of one molecule of each of two monosaccharides—glucose and fructose. Sucrose is found in fruits and vegetables and is particularly plentiful in sugar beets (roots) and sugarcane (a grass). Refined white and brown sugars are close to 100% sucrose because almost everything else (including the other kinds of sugars present, the vitamins, the minerals and the proteins) have been removed in the refining process. Maple syrup and molasses are, like refined sugars, unwholesome sweeteners; both contain over 50% sucrose. It almost goes without saying that any foods, so-called, containing significant amounts of refined sugar are high in sucrose.

2.7 Maltose (also known as malt sugar)

This disaccharide, unlike sucrose, is not consumed in large amounts in the average American diet. It is found in malted cereals, malted milks and sprouted grains. Also, corn syrup is 26 percent maltose and corn sugar is 4 percent maltose. None of these "foods" is wholesome, with perhaps, the exception of sprouted grains.

Maltose occurs in the body as an intermediate product of starch digestion. (Starch is a polysaccharide.) When maltose is hydrolyzed, it yields two molecules of glucose.

2.8 Lactose (also known as milk sugar)

This disaccharide is found only in milk. Human milk contains about 4.8 g per 100 ml and cow's milk contains approximately 6.8 g per 100 ml. When lactose is hydrolyzed it yields one unit of the monosaccharide glucose and one unit of the monosaccharide galactose. The enzyme lactase is needed to digest lactose, and this enzyme is not present in most, if any, people over age three. This is one of the many reasons why milk is an unwholesome food for people over three years of age.

2.9 Polysaccharides

Like the disaccharides, the polysaccharides cannot be directly utilized by the body. They must first be broken down into monosaccharides, the only sugar form the body can use.

Polysaccharides contain up to 60,000 simple carbohydrate molecules. These carbohydrate molecules are arranged in long chains in either a straight or in a branched structure. There are four polysaccharides that are important in the study of nutritional science: starch, dextrin, glycogen and cellulose.

2.10 Starch

Starch is abundant in the plant world and is found in granular form in the cells of plants. Starch granules can be seen under a microscope and they differ in size, shape and markings in various plants. The starch granules of wheat, for example, are oval-shaped; whereas the starch granules of corn are small, rounded and angular.

These starch granules are laid down in the storage organs of plants—in the seeds, tubers, roots and stem pith. They provide a reserve food supply for the plant, sustain the root or tuber through the winter and nourish the growing embryo during germination.

Most starches are a mix of two different molecular structures, amylose and amylopectin. The former has a linear structure and the latter has a branched or bushy structure. The proportion of the two fractions varies according to the species of plant. For example, potato starch and most cereal starches have approximately 15-30% amylose. But the waxy cereal grains, including some varieties of corn plus rice and grain sorghum, have their starch most entirely as amylopectin. The starches in green peas and in some sweet corn varieties are mainly amylose.

The polysaccharides, as mentioned earlier, are not water soluble as are the mono- and disaccharides. Though not water soluble, starches can be dispersed in water heated to a certain temperature. The granules swell and gelatinize. When cooled, this gelatin sets to a paste. The jelling characteristics of starches are considered to result from the amylose present, while amylopectin is considered to be responsible for the gummy and cohesive properties of the paste.

2.11 Dextrin

There are several "varieties" of this polysaccharide. Dextrins are most commonly consumed in cooked starch foods, as they are obtained from starch by the action of heat. Dextrins are intermediary products of starch digestion, also, and are formed by the action of amylases on starches. They render the disaccharide maltose on hydrolysis.

2.12 Glycogen

Glycogen is the reserve carbohydrate in humans. It is to animals as starch is to plants. Glycogen is very similar to amylopectin, having a high molecular weight and branched-chain structures made up of thousands of glucose molecules. The main difference between glycogen and amylopectin is that glycogen has more and shorter branches, resulting in a more compact, bushlike molecule with greater solubility and lower viscosity (less stickiness or gumminess).

Glycogen is stored primarily in the liver and muscles of animals. About two-thirds of total body glycogen is stored in the muscles and about one-third is stored in the liver.

2.13 Cellulose

Like starch and glycogen, cellulose is composed of thousands of glucose molecules. It comprises over 50% of the carbon in vegetation and is the structural constituent of the cell walls of plants. Cellulose is, therefore, the most abundant naturally-occurring organic substance. It is characterized by its insolubility, its chemical inertness and its physical rigidity. This polysaccharide can be digested only by herbivores such as cows, sheep, horses, etc., as these animals have bacteria in their rumens (stomachs) whose enzyme systems break down cellulose molecules. Humans do not have the enzyme needed to digest cellulose, so it is passed through the digestive tract unchanged.

ECG 3-Normal Sinus Rhythm (NSR)

•    Etiology: the electrical impulse is formed in the SA node and conducted normally.

•    This is the normal rhythm of the heart; other rhythms that do not conduct via the typical pathway are called arrhythmias.


NSR Parameters
•    Rate                60 - 100 bpm    
•    Regularity            regular
•    P waves            normal
•    PR interval            0.12 - 0.20 s
•    QRS duration        0.04 - 0.12 s
Any deviation from above is sinus tachycardia, sinus bradycardia or an arrhythmia



Arrhythmia Formation
Arrhythmias can arise from problems in the:
•    Sinus node
•    Atrial cells
•    AV junction
•    Ventricular cells


SA Node Problems
The SA Node can:
fire too slow--- Sinus Bradycardia

fire too fast--- Sinus Tachycardia




Atrial Cell Problems
Atrial cells can:

•    fire occasionally from a focus ---Premature Atrial Contractions (PACs)

•    fire continuously due to a looping re-entrant circuit ----Atrial Flutter 



Atrial Cell Problems
Atrial cells can also:
• fire continuously from multiple foci Atrial Fibrillation

or
fire continuously due to multiple micro re-entrant “wavelets” Atrial Fibrillation




AV Junctional Problems
The AV junction can:

•    fire continuously due to a looping re-entrant circuit--Paroxysmal   Supraventricular Tachycardia
•    block impulses coming from the SA Node--AV Junctional Blocks



Ventricular Cell Problems
Ventricular cells can:
•    fire occasionally from 1 or more foci --Premature Ventricular Contractions (PVCs)
•    fire continuously from multiple foci--Ventricular Fibrillation
•    fire continuously due to a looping re-entrant circuit--Ventricular Tachycardia

ECG 2 -How to Analyze a Rhythm

• Step 1: Calculate rate.
• Step 2: Determine regularity.
• Step 3: Assess the P waves.
• Step 4: Determine PR interval.
• Step 5: Determine QRS duration.

Step 1: Calculate Rate

• Option 1
– Count the # of R waves in a 6 second rhythm strip, then multiply by 10.
– Reminder: all rhythm strips in the Modules are 6 seconds in length.

Interpretation? 9 x 10 = 90 bpm



• Option 2

– Find a R wave that lands on a bold line.
– Count the # of large boxes to the next R wave. If the second R wave is 1 large box away the rate is 300, 2 boxes - 150, 3 boxes - 100, 4 boxes - 75, etc. 
– Memorize the sequence:
300 - 150 - 100 - 75 - 60 - 50



Step 2: Determine regularity

• Look at the R-R distances (using a caliper or markings on a pen or paper).
• Regular (are they equidistant apart)? Occasionally irregular? Regularly irregular? Irregularly irregular?

Interpretation? Regular




Step 3: Assess the P waves

• Are there P waves?
• Do the P waves all look alike?
• Do the P waves occur at a regular rate?
• Is there one P wave before each QRS?
Interpretation? Normal P waves with 1 P wave for every QRS



Step 4: Determine PR interval

• Normal: 0.12 - 0.20 seconds.
(3 - 5 boxes)

Interpretation?0.12 seconds



Step 5: QRS duration

• Normal: 0.04 - 0.12 seconds.
(1 - 3 boxes)
Interpretation? 0.08 seconds



Rhythm Summary

• Rate 90-95 bpm 
• Regularity regular
• P waves normal
• PR interval 0.12 s
• QRS duration 0.08 s
Interpretation?  Normal Sinus Rhythm