EKG Interpretation 3 – Junctional Rhythms
Apr 29th, 2009 by
RH-111
Print This Post
Andy Rodriguez
Impulse is generated somewhere near the AV node. Impulses can travel up or down causing absent or inverted P wave – sometimes after the QRS. QRS is normal and tight.
Premature Junctional Contraction (PJC)
Irritable site in AV junction fires prematurely producing a single ectopic beat.
Regularity depends on underlying rhythm
Rate – same
P Wave: Inverted, can fall before, during or after QRS
PRI, if measurable, <.12
QRS <.12
Junctional Escape Rhythm
Higher pacemaker sites fall and AV junction takes over, atria are depolarized via retrograde conduction. Ventricular conduction is normal.
Regular
Rate: 40-60
P Waves, inverted, during or after QRS
PRI – only if there is a P wave and before and will be <.12
QRS <.12
Accelerated Junctional Rhythm
Irritable focus in the AV junction fires repeatedly at a rate faster than the SA node. Retrograde conduction to atria and conduction to ventricles is normal
Regular
Rate: 60-100
P Wave: inverted, before or after QRS
PRI – only if there is a P wave and before and will be <.12
QRS <.12
Junctional Tachycardia
Irritable focus in the AV junction fires repeatedly at a rate faster than the SA node. Retrograde conduction to atria and conduction to ventricles is normal
Regular
Rate: 100-180
P Wave: inverted, before or after QRS
PRI – only if there is a P wave and before and will be <.12
QRS <.12
Supraventricular Tachycardia (SVT)
Rapid, Regular, SV rhythm that is so fast that you cant see P waves. Normal QRS
Rate >150
Paroxysmal Supraventricular Tachycardia (PSVT)
A short burst of SVT that occurs in a rhythm strip
Respiratory – Review Questions
Apr 27th, 2009 by
RH-111
Print This Post
Some exam review for Respiratory emergencies:
1. A person who experiences sharp chest pain followed by increasing dyspnea after he or she coughs MOST likely has:
Choose one answer.
A. pleurisy.
B. acute pneumonia.
C. a pleural effusion.
D. a pneumothorax.
2. An otherwise healthy adult whose normal hemoglobin level is 12 to 14 g/dL typically will begin to exhibit cyanosis when:
Choose one answer.
A. hemoglobin levels fall below 12 g/dL.
B. about 5 g/dL of hemoglobin is desaturated.
C. his or her oxygen saturation falls below 50%.
D. 10% of his or her hemoglobin is desaturated.
3. Intrapulmonary shunting occurs when:
Choose one answer.
A. hyperinflated alveoli retain high levels of carbon dioxide.
B. resistance to airflow increases due to bronchoconstriction.
C. nonfunctional alveoli inhibit pulmonary gas exchange.
D. the volume of anatomic dead space suddenly increases.
4. A patient with status asthmaticus commonly presents with:
Choose one answer.
A. compensatory respiratory alkalosis and stridor.
B. physical exhaustion and inaudible breath sounds.
C. audible expiratory wheezing and severe cyanosis.
D. accessory muscle use and inspiratory wheezing.
5. __________ breath sounds are the MOST commonly heard breath sounds, and have a much more obvious inspiratory component.
Choose one answer.
A. Vesicular
B. Tracheal
C. Bronchovesicular
D. Bronchial
6.
A 29-year-old woman is experiencing a severe asthma attack. Her husband reports that she was admitted to an intensive care unit about 6 months ago, and had a breathing tube in place. Prior to your arrival, the patient took 3 puffs of her rescue inhaler without effect. She is anxious and restless, tachypneic, and has audible wheezing. You should:
Choose one answer.
A. attempt to slow her breathing with respiratory coaching, administer a nebulized bronchodilator, and transport.
B. start an IV of normal saline, administer methylprednisolone via IV push, and transport as soon as possible.
C. apply a CPAP unit, transport immediately, and attempt to establish vascular access en route to the hospital.
D. begin assisting her ventilations with a bag-mask device and 100% oxygen and prepare to intubate her trachea.
7. The presence of diffuse rhonchi in the lungs indicates:
Choose one answer.
A. thick secretions in the large airways.
B. isolated consolidation of secretions.
C. right-sided congestive heart failure.
D. air being forced through narrowed airways.
8. Uncontrollable coughing and hemoptysis in a cigarette smoker are clinical findings MOST consistent with:
Choose one answer.
A. acute bronchitis.
B. lung cancer.
C. emphysema.
D. pleural effusion.
Pediatric Shock
Apr 27th, 2009 by
RH-111
Print This Post
Chapter 358: Shock
Copied from the AAP Textbook of Pediatric Care
Chapter 358: Shock
Monika Gupta, MD; Joseph R. Custer, MD
CLASSIFICATION OF SHOCK
Shock can be classified by cause and mechanism: hypovolemic, cardiogenic, and distributive. Again, the primary clinician should recall that despite complexities of cause, the early stages of shock are easy to recognize, and the treatments are straightforward.[13]
HYPOVOLEMIC SHOCK
Shock from loss of blood volume caused by trauma, diarrhea, burns, and 3rd spacing (as in peritonitis) is the most common form of shock in children. Loss of fluid leads to low intravascular volume and preload to the heart is decreased. If such losses (up to 30% of circulating blood volume) occur over days, then patients can compensate by increasing thirst, heart rate, and retention of fluid by concentrating urine. Large volumes of fluid loss that occur acutely lead to decompensation represented by diminished mental status, tachycardia, poorly perfused skin with prolonged capillary refill, oliguria, and, eventually, hypotension.
Nonhemorrhagic shock is seen in diarrhea, vomiting, urinary losses, evaporative losses, 3rd spacing of fluid (peritonitis, edema), and burns. The causes of hypovolemic shock are seen in BOX 358-2 .
Physical signs in hypovolemic shock occur as a result of decreased venous return to the heart, which leads to diminished cardiac output. Catecholamines are released, which produces the hallmark vasoconstriction in skin, muscle, and splanchnic blood vessels. The renin-angiotensin system is activated, promoting the retention of salt and water. Fluid resuscitation restores preload, and cardiac output is increased with resolution of symptoms. Physical signs in dehydration reliably indicate the percentage of body fluid compartment losses (Table 358-3 ). In hemorrhagic shock, physical findings correlate to the amount of blood loss[15] (Table 358-4 ).
BOX 358-2: Causes of Hypovolemic Shock
Gastrointestinal losses
Excess urine output, diuretic agent administration
Mannitol administration
Hypoalbuminemia
Burns
3rd space fluid losses (peritonitis, edema)
Traumatic blood loss
Table 358-3: Physical Signs in Dehydration
Percentage of Dehydration
Physical Signs
5% (mild)
Dry skin, mild tachycardia, concentrated urine
10% (moderate)
Lethargy, poor perfusion
15% (severe)
Obtundation, tachycardia, hypotension, very poor perfusion to skin
Table 358-4: Physical and Vital Signs in Hemorrhagic Shock
Blood Volume Lost (%)
Signs
<15%
Minimal tachycardia, normal respiratory rate, blood pressure, and capillary refill
15-30%
Tachycardia, tachypnea, decreased pulse pressure, normal systolic pressure, prolonged capillary refill, anxiety
30-40%
Hypotension, decreased urine output, mental status changes
>40%
Hypotension, loss of consciousness
CARDIOGENIC SHOCK
Cardiac shock can be caused by mechanical obstruction or muscle (pump) failure. In obstructive cardiogenic shock, air and fluid in the pericardium or pleural spaces (rarely) can impede venous return to the heart and decrease systolic ejection. Common causes are listed in BOX 358-3 . These patients usually exhibit distended neck veins because of increased jugular venous pressure and hypotension. Massive pulmonary embolus, rare in children, can obstruct flow from the right to the left side of the heart. In coarctation of the aorta, hypoplastic left heart syndrome, and left ventricular outflow tract stenosis, cardiac output is compromised.
The heart can fail as a mechanical pump from a variety of causes (BOX 358-4 ). Patients with cardiac failure have low cardiac output resulting in the clinical signs of altered mental status, tachycardia, decreased capillary refill, and evidence of venous congestion (hepatomegaly, rales). Children with pericardial effusion may have muffled heart tones.
BOX 358-3: Causes of Obstructive Cardiogenic Shock
Tamponade (air, blood, or effusion)
Coarctation of the aorta
Aortic valve stenosis or atresia
BOX 358-4: Pump Failure
Arrhythmia
Hypoplastic left heart syndrome
Decreased contractility acquired in sepsis syndrome or shock of any cause
Myocardiopathy
Myocarditis
Anomalous coronary artery
Cardiac contusion
Storage disease—glycogen storage disease
SEPTIC SHOCK
Septic shock is the most common and certainly best-studied cause of cardiovascular collapse the primary caregiver will encounter.[9] The causes of bacterial septic shock have changed since vaccination against Haemophilus influenzae type b was instituted in 1988. If sepsis in the (increasingly common) immunocompromised patient is excluded, meningococci and streptococci are then the most frequently encountered bacterial causes of sepsis.
Patients with infections caused by Staphylococcus aureus, Pseudomonas aeruginosa , Candida species, and Streptococcus pyogenes have higher mortality rates compared with patients with infections caused by coagulase-negative Staphylococcus and Acinetobacter species.[16]
Studies of children who have meningococcemia highlight important issues in the care of children in septic shock (see Chapter 353 , Meningococcemia). Mortality remains high despite modern advances in critical care.[17] An unfortunate characteristic of meningococcal disease is its rapid progression in fatal cases. Characteristics of cases rapidly progressing to death include young age, absence of meningitis, thrombocytopenia, leukopenia, multiorgan failure, and severity of petechiae.[17] Invasive meningococcal disease is most common in children younger than 4 years. Meningitis and sepsis occurs in 1.3:100,000 in the United States, but incidence in Ireland is 15:100,000.[17] Clinicians who encounter these clinical stigmata in primary care settings should recognize the importance of early stabilization, the need for referral for definitive therapy, and the high mortality despite aggressive intervention.
Children and adults exhibit developmental differences in the hemodynamic response to sepsis. In adults, mortality is caused by a pressor and volume resistant state characterized as vasomotor paralysis. Myocardial dysfunction is common in adults, but cardiac output is maintained by tachycardia and ventricular dilatation.[7] [18]
In pediatric septic shock, low cardiac output, not vasodilatation, is associated with mortality.[19] In children, oxygen delivery is the major determinant of oxygen consumption, whereas in adults, oxygen used by tissues (oxygen extraction) is more important. Survival correlates to the restoration of cardiac output and oxygen delivery.[8] [20]
Some patients with severe septic shock may develop a hypoadrenal response to shock. This scenario is clinically characterized as patients who are in refractory shock (see Table 358-2 ) who are, by definition, unresponsive to volume resuscitation, the addition of 2 catecholamine drugs, and normalization of acid base, glucose, and calcium homeostasis. Infants and children at risk include those with septic shock and purpura, those with known or suggested adrenal abnormalities, and children who have received a therapeutic course of steroids in the 6 months before the onset of sepsis.[21]
In patients whose shock state is refractory to volume, dopamine or dobutamine, and the addition of epinephrine or norepinephine (catechol resistant shock), empirically initiating stress-dose steroids (hydrocortisone at stress doses of 50 to 100 mg/m[2] /day would be reasonable. If time and condition allow it, a baseline serum cortisol level is drawn, followed by a 250 microgram dose of corticotropin, and a repeat cortisol level is drawn at 30 minutes. The response (or absence of) will determine the presence of a hypoadrenal state and the need for continued steroid administration. A baseline serum cortisol of less than 18 Tg/dL and a poststimulation increment of less than 9 Tg/dL indicate a hypoadrenal state.[9] [21] If a stimulation test cannot be done, then continued steroid therapy for 3 to 5 days should be based on clinical response.
DISTRIBUTIVE SHOCK
In distributive shock disorders, global disorder in vasomotor control is present, resulting in maldistribution of blood flow and oxygen to tissue. Anaphylaxis and spinal cord injury are the 2 types most likely to be encountered in primary care. Cardiac output may be normal or increased. These patients lose sympathetic control of the vascular system, which reduces peripheral vascular tone. This circumstance produces pooling of blood in the periphery, which, in turn, leads to decreased venous return to the heart.
In anaphylactic shock, the inciting agent should be removed if possible. These patients uniformly respond well to volume administration, epinephrine infusion, antihistamines that include an H2 -receptor blocker, and steroid therapy.
The Nervous System
Apr 26th, 2009 by
RH-111
Print This Post
John Clappin
Three Qualities
Monitors internal & external environments
Integrates sensory information
coordinates voluntary and involuntary responses of many other organ systems
Central Nervous System (CNS)
Peripheral Nervous System (PNS) Central (Nerves and Ganglia)
Sensory- Afferent
Exteroreceptors (Touch, Temp, Pressure, Smell, etc)
Proprioreceptors (Position and movement of skeletal muscles)
Interoreceptors – (monitor digestive, respiratory, cardiovascular, urinary and reproductive systems and taste)
Peripheral ganglions
Processing – Interneuron, then on to the;
Somatic motor neurons – skeletal muscles
Visceral motor neurons – smooth muscle, glands, cardiac muscles, fat cells
Motor – Efferent
Voluntary – Somatic
Involuntary – Autonomic
Sympathetic
Parasympathetic
Types of Nervous Tissues
Neurons – basic unit of the nervous system (do not reproduce)
Dendrites – afferent – inbound
Cell Body
Axon Hillock (delta shaped as cell body becomes an axon)
Axon – Efferent
Axon Collaterals (off side of axons)(branches to different portions of muscles)
Axon Terminals
Synaptic End Bulbs (Neuromuscular terminal)
Synaptic Cleft
Dendrite of next neuron or effector organ
Types of Neurons
Multipolar – most common in CNS
Unipolar – most sensory neurons of PNS
Bipolar – rare in special sense organs (sight smell, hearing)
Saltatory Conduction ( impulses pause at breaks in myelin, draws in sodium)
Neuron
Neuroglia – neuro glial cells – regulate the environment around the neurons providing support for neural tissue (do reproduce)
Ependymal Cells -secrete CSF
Astrocyte – largest and most numerous, secretes chemicals vital to maintain the blood-bran barrier which isolates CNS from general circulation.
Oligodendrocytes – secrete myelin to neural axons (myelin – makes them white, permits and controls movement of ions don the axon and does not go into surrounding tissues – insulation). Some cells are myelinated and some are unmyelinated. Multiple Sclerosis is a degenerative disease affecting myelin production.
Schwann Cell – PNS cell similar to Oligodendrocytes – covers every axon in the PNS Everything white is myelin. Everything gray is accumulated cells.
Neural Communication
Chemical Neurotransmitters – information transfer at synaptic terminals occur via the release of neurotransmitters.
Norepinephrin (primary sympathetic neurotransmitter)
ACh (primary parasympathetic neurotransmitter) (AChE breaks it down in the cleft to allow the receptors to open for the next transmission)
Dopamine
GABA
Serotonin
Melatonin
etc,
Synaptic Cleft
Nerves
Cell bodies are frequently grouped together;
In CNS – called Nuclei, Nucleus
Outside CNS – called Ganglion,Ganglia
Fascicle – groups of neurons bundled together, surrounded by connective tissue. Nerves contains multiple bundles of fascicles(outside CNS, inside CNS called Tracts)
Anatomy of the Spinal Cord
Starts at Foramen Magnum – runs down to L1
Cervical region is thicker, called cervical enlargement – same at bottom, called lumbar enlargement
Conus medullaris – cone like end of SC
Cuada Equina – after spinal cord ends – threadlike (spinal taps, epidurals, etc. happen here)
32 spinal nerves – beneath each of the vertebrae
Nerves from spinal cord contain both efferent and afferent neurons – split just before spinal cord – dorsal roots (sensory – with dorsal ganglia) and ventral roots (purely motor – cell bodies in are in the spinal cord)
Grey Horns (anterior and posterior) Anterior and Posterior White Columns (contain tracts) (posterior – ascending tracts, anterior – descending tracts)
Central canal – contains CSF
Meninges
Pia Mater – first protective layer of spinal cord (very tightly wrapped) Subarachnoid space – between pia mater and arachnoid layer – filled with CSF
Arachnoid layer – looks like a spider’s web Spinal dura mater
The Brain
cerebral cortex - is a structure within the brain that plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. cerebrum
divided into cerebral hemispheres
diencephelon
Hollow, largest portion is the thalamus – which contains relay and processing for sensory information. Hypothalamus is connected to the pituitary gland. The hypothalamus contains centers involved with emotions,autonomic function and hormone production. The pituitary gland is the prmary link between the nervous and endocrine systems.
Brain Stem (responsible for all vegetative function and almost all cranial nerves originate here)
midbrain – process visual and auditory information and generate involuntary responses. also has regions that help maintain consciousness. pons – or bridge, connects cerebellum to brain stem. also contains tracts involved in visceral and somatic control. Also connected to the medulla oblongata medulla oblongata – segment of brain attached to the spinal cord. relays information to the thalamus and other parts. regulates lots of autonomic function including heart rate,BP, respiration and digestion.
cerebellum – adjust voluntary and involuntary motor activities based on sensory information and stored memory of previous movements. Ventricles – 1st through 4th – chambers filled with CSF
The Peripheral Nervous System (PNS)
12 Pairs of Cranial Nerves (future post – see table 8-2 on page 297) Nerve Plexus – PNS network of intersecting nerves
Cervical plexus – serves the head, neck and shoulders Brachial plexus – serves the chest, shoulders, arms and hands Lumbar plexus – serves the back, abdomen, groin, thighs, knees, and calves Sacral plexus – serves the pelvis, buttocks, genitals, thighs, calves, and feet Solar plexus – serves internal organs Coccygeal plexus – Same as Solar Plexus
Since the Lumbar and Sacral plexus are interconnected, they are sometimes referred to as the Lumbosacral plexus. The nerves that serve the chest are the only ones that do not originate from a plexus
Dermatomes
EKG Interpretation –2
Apr 22nd, 2009 by
RH-111
Print This Post
More on EKGs … Andy Rodriguez
Escape Mechanism – normal pacemaker slows down or fails and a lower pacing site assumes pacemaking responsibility.
Sympathetic – both Atria & ventricles
Analyzing the rhythm
Regularity – Rhythm
regular
irregular
pattern to irregularity
ectopic beats
Rate P Waves
present
regular, one for every QRS
before QRS or after
deflection – normal and upright in lead II
all P waves look alike
are irregular P waves associated by ectopic beats
PR Intervals (PRI) QRS Complex
equal duration
measurement
normal limits
all look alike?
are unusual QRS complexes associated with ectopic beats?
Sinus Rhythms
Normal Sinus Rhythm – Regular, 60-100 BPM, P waves normal and upright, one before every QRS, PRI 0.12-0.20 and QRS <0.12
Sinus Bradycardia - Regular, Rate <60 BPM, P waves normal and upright, one before every QRS, PRI 0.12-0.20 and QRS <0.12
Sinus Tachyardia - Regular, Rate >100 BPM (usually 100-160), P waves normal and upright, one before every QRS, PRI 0.12-0.20 and QRS <0.12
Sinus Arrhythmia – sinus node fires faster during inspiration and slower during expiration. rate is still normal, and still normal QRS –
Atrial Rhythms
Wandering Pacemaker – pacemaker site wanders between SA node, atria and AV node. rate is usually normal and will conduct normally to ventricles
Premature Atrial Contraction (PAC) – irritable focus within atrium that fires prematurely and produces a single ectopic beat. impulses are conducted normally.
Atrial Tachycardia (or SVT)– Single atrial site fires repetitively at a very high rate. impulses conducted normally
Atrial Flutter - single focus initiates rapid repetitive impulses, AV node protects ventricles by blocking conduction of some impulses. Atrial Rhythm- regular , several flutter waves (saw tooth)before each QRS (F waves), PRI unable to determine, atrial rate 250-350 bpm
Atrial Fibrillation – multiple foci initiate rapid repetitive impulses, AV node protects ventricles by blocking conduction of some impulses. Grossly irregular , atrial rate >350 bpm, ventricular rate varies greatly, no discernable P waves , no PRI, QRS <.12
EKGs – Part 1
Apr 20th, 2009 by
RH-111
Print This Post
Steve Kanarian
Some cardiology review:
Location of Heart: Retrosternal
Point of maximal impulse, Left 5th intercostal, midclavicular line, above mitral valve as well.
Pericardium contains approx 30cc of fluid
CO= SV x HR
Frank Starling Law – (use fluid challenge to increase CO, increase in volume = increase in stretch therefore increase CO)
S1 – closing of mitral and tricuspid valves
s2 – closing of pulmonic and aortic valves
s3 – murmur, caused by ventricular filling, caused by left sided CHF
s4 – sign of CHF
Coronary Vessels come off base of aorta and come back via the coronary sinus
right coronary artery (RCA) (right atrium and ventricle)
left coronary artery (LCA) splits; (mostly left ventricle and atrium)
left anterior descending
circumflex coronary
Preload; pressure in ventricle at diastole
Afterload; pressure against which heart has to pump
Depolarization causes contraction.(Na+ rushes in) Repolarization is the refractory state. (K+ left in the cell)
Cardiac Physiology
(Bundle of Kent – Wolf Parkinson’s White –WPW)
EKG Lead Placement
Bipolar (Limb) Leads – impulses traveling towards positive lead, upright wave, going towards negative lead, points down
Augmented (Unipolar) Leads – Boosted Electrically)
Precordial (Chest) Leads- V1-V6 (Septal 1,2, Anterior 3,4 Lateral 5,6 Inferior 2,3, aVF) SALI
Electrical Conductivity and the EKG
‘Monitoring’ leads are not diagnostic, 12 Lead EKG Machines are diagnostic quality
ECG Paper
Speed (horizontal Boxes smallest= .04 sec, big box is .20 sec)
Amplitude – Vertical box = 0.1mV height (1mm)
Normal Electrocardiogram
P-R Interval (PRI) – 0.12 – .20 sec (Prolonged PRI indicates Heart block)
QRS – <0.12 sec – wider indicates rhythm below AV node
QT interval – Q wave to repolarization – prolonged means heart is at risk for ventricular dysrythmias (poisoning, overdoses)
5 points to look for
Rate
Rhythm
P waves
PRI
QRS
