PBL 1 Flashcards
1
Q
What are 7 different types of Pneumothorax?
A
Primary Spontaneous Pneumothorax (PSP)
Secondary Spontaneous Pneumothorax (SSP)
Closed Pneumothorax
Open Pneumothorax
Traumatic Pneumothorax
Iatrogenic Pneumothorax
Tension Pneumothorax
2
Q
What is Primary Spontaneous Pneumothorax, what are the symptoms and what are the 6 predisposing risk factors?
A
Primary Spontaneous Pneumothorax (PSP) tends to occur in young people without underlying lung problems and usually causes limited symptoms. Chest pain and mild breathlessness are the main symptoms. Risk factors:
Male 15-30, Smoking, Tall stature, Apical subpleural blebs, Atmospheric pressure changes, Exposure to loud music.
3
Q
What is Secondary Spontaneous Pneumothorax (SSP?). When should you suspect it? Which patients is it most common in?
How does it compare to PSP?
A
SSP occurs by definition in those with underlying lung disease. The symptoms tend to be more severe, as the unaffected lung is less able to compensate for the affected side. The size of the pneumothorax bears little relationship to the symptoms.
Suspect it if you see sudden breathlessness in someone with underlying problem such as CF, COPD. Most common in older patients.
More severe symptoms and higher mortality rate than PSP.
4
Q
Describe closed pneumothorax. How is it resolved? What problem is uncommon with closed pneumothorax?
A
Air leaks from the lungs into the pleural cavity. The pneumothorax is called closed if the opening between the lung and the pleural cavity seals off while the lung is deflating, and does not reopen. In this case, the pleural pressure stays negative and reabsorption of the air and reexpansion of the lungs will occur in a few days or weeks. Infection is uncommon.
5
Q
Describe open pneumothorax. What are some conditions that cause this? (3)
A
In open pneumothorax, the opening between the lung and pleural cavity does not close, so the pressure in the pleural cavity is the same as atomspheric pressure. Air continues to move between the lung and pleural space.
Commonly seen after the rupture of an emphysematous bulla, tuberculous cavity or lung abcess into the pleural space.
6
Q
What types of treatment may cause iatrogenic pneumothorax? (3)
A
1) intrathoracic surgery
2) thoracentesis (pleural tap to remove fluid or air)
3) placement of chest drain
7
Q
What are some causes of tension pneumothorax? (3)
A
1) Traumatic injury
2) Chronic Lung Disease
3) result of a medical procedure (iatrogenic)
8
Q
What is the mechanism of tension pneumothorax? What dangerous effects does this condition have?
A
If the hole between the airway and the pleura is small, the wound can act as a one way valve, so air enters the chest cavity but cannot escape. The intrapleural pressure may rise to well over atmospheric levels. This greatly increased pressure in the pleural space causes the lung to collapse completely, compresses the heart and pushes the heart and associated blood vessels towards the unaffected side. The impairment of systemic venous return causes cardiovascular compromise.
9
Q
Which patients may have a tension pneumothorax which is difficult to spot?
A
Tension pneumothorax may occur in those receiving mechanical ventilation, in which case it may be difficult to spot as the person is typically sedated; it is often noted because of sudden deterioration.
10
Q
Which signs of tension pneumothorax should you not rely on?
A
Deviation of the trachea (windpipe) to one side and the presence of raised jugular venous pressure (distended neck veins) are not reliable as clinical signs
11
Q
What are three unusual causes of pneumothorax?
A
- Acupuncture (rarely)
- Scuba diving.
- Flying at high altitudes
12
Q
What are the symptoms of spontaneous pneumothorax? (7)
A
- Pain: One sided, Dull, sharp, or stabbing, Sudden onset, becomes worse with deep breathing or coughing.
- Shortness of breath
- Rapid breathing
- Hypoxaemia (decreased blood oxygen) maybe cyanosis (blue lips)
- Abnormal breathing movement (that is, little chest wall movement when breathing)
- Cough
- Hypercapnia (accumulation of carbon dioxide in the blood) is sometimes encountered; this may cause confusion and coma.
In patient with a small pneumothorax the exam may be normal
13
Q
How do you diagnose simple (non tension) pneumothorax?
A
The combination of absent breath sounds and resonant percussion note is diagnostic of pneumothorax
14
Q
What are the three main stages of treatment for simple (non tension) pneumothorax?
A
1) do nothing: if the pneumothorax is small enough, it may resolve on its own, but most need treatment.
2) Re-expand the lung by removing air from the chest. This is done by inserting a needle and syringe (if the pneumothorax is small) or chest tube through the chest wall. The lung will then re-expand itself within a few days.
3) Surgery may be needed for repeat occurrences : Pleurectomy, pleural abrasion.
15
Q
What are the two procedures you can do to drain air from the chest, and which patients do you do them on?
A
- Percutaneous needle aspiration of air: perform on young patients with a moderate or large spontaneous primary pneumothorax: a simple and well tolerated alternative to intercostal tube drainage with a 60-80% chance of avoiding the need for a chest drain.
- Intercostal Chest Tube: In patients with underlying chronic lung disease even a small secondary pneumothorax may cause respiratory failure; hence all such patients require intercostal tube drainage and inpatient observation.
16
Q
How do you fit an intercostal chest drain? What do you look out for while the drain is in place?
A
Insert Intercostal drains into the 4th 5th or 6th intercostal space in the mid axilliary line. Advance tube in an apical direction. Use an underwater seal or one-way Heimlich valve. Secure the tube firmly to the chest wall.
Look for continued bubbling after 5-7 days: this is an indication for surgery. If bubbling in the underwater bottle stops prior to full reinflation, the tube is either blocked, kinked or displaced.
17
Q
When do you remove a chest drain? What should you never do with a chest drain?
A
- The drain should be removed 24 hours after the lung has been fully reinflated and the bubbling stopped. Continued bubbling after 5-7 days is an indication for surgery.
- Clamping of the drain is potentially dangerous and is never indicated
18
Q
What treatment do you always give spontaneous pneumothorax patients, even if you are draining them, and why?
A
All patients should receive supplemental oxygen as this accelerates the rate which air is reabsorbed into the pleura.
19
Q
How do you control pain and discomfort in a pneumothorax patient? When is the patient allowed to resume daily activities, and what advice are they given?
A
- Pain: appropriate analgesics, but the use of respiratory depressants is avoided.
- The patient usually is more comfortable if allowed to sit up.
- As soon as the lung lesion heals and the lung is reexpanded, the patient can resume usual daily activities
- The patient is taught how to turn, cough, breathe deeply, and perform passive exercises and is told to avoid stretching, reaching, or making sudden movements.
- Advise not to smoke, drink fluids copiously, exercise, avoid fatigue and strenuous activity.
20
Q
What is the risk of recurrrence of primary spontaneous pneumothorax?
A
After primary spontaneous pneumothorax, recurrence occurs within a year of either aspiration or tube drainage in approximately 25% of patients, and should prompt definitive treatment with surgery.
21
Q
What is pleurodesis and what are the indications for it?
A
Surgical pleurodesis is recommended:
- in all patients following the recurrence of PSP
- following the first episode of SSP if low respiratory reserve makes recurrence hazardous.
- for patients who plan to continue activities where pneumothorax would be dangerous (Eg flying or diving) after the first episode of PSP
Pleurodesis can be achieved by plural abrasion or parietal pleurectomy
22
Q
How is pleurodesis carried out?
A
Pleurodesis procedure: the pleural space is destroyed by the adhesion of the two pleurae.
Can be done chemically or surgically.
- Chemicals, usually a slurry of talc, are introduced into the pleural space through a chest drain. This causes irritation between the parietal and the visceral layers of the pleura causing them to stick together.
- Surgical pleurodesis involves mechanically irritating the parietal pleura, often with a rough pad.
- Surgical removal of parietal pleura is an effective way of achieving stable pleurodesis.
23
Q
What are the causes of tension pneumothorax? (3)
A
- Trauma: a penetrating chest wound allows outside air to enter the chest, causing the lung to collapse. Air cannot escape from chest cavity because the wound becomes a one way valve.
- Hidden injury, such as a fractured rib, that punctures the lung.
- Lung conditions
24
Q
What are the common (5) and more unusual symptoms (10) of tension pneumothorax?
A
Common Symptoms:
Severe sudden Chest pain, Respiratory distress, Tachycardia, Rapid breathing, Marked anxiety.
Less Frequent Symptoms:
Distended neck veins, Hypoxaemia maybe cyanosis, Weak pulse, Decreased breath sounds on the affected side, Shift of the mediastinum to the opposite side, Hypotension, Diaphoresis (excessive sweating), Elevated temperature, Pallor, Dizziness
25
How do you distinguish between pneumothorax on an Xray and emphysematous bullae?
Care must be taken to differentiate betwee a large pre-existing emphysematous bulla (single or multiple large alveolar cysts seen in emphysema) and and a pneumothorax to avoid misdirected attempts at aspiration. Where doubt exists, CT is useful for distinguishing bullae from pleural air.
26
Why is tension pneumothorax so dangerous?
Tension pneumothorax can cause death rapidly due to inadequate heart output or insufficient blood oxygen (hypoxemia), and must be treated as a medical emergency.
27
What is the autonomic nervous system ANSI what does it control?
What is it part of?
What is it in contrast to?
What does it control? (8 examples)
The autonomic nervous system (ANS or visceral nervous system) is the part of the peripheral nervous system PNS.
It acts as a control system functioning largely un-consciously, and controls visceral functions.
It stands in contrast to the somatic nervous system, (SNS) which exerts conscious control over skeletal muscles.
The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils, micturition (urination), and sexual arousal.
28
What type of nervous divisions are the SNS and the ANS?
They are efferent: that is they take information away from the centre towards the periphery.
29
What is the main structural difference between the SNS and the ANS?
In the SNS, motor neurone of the CNS exert direct control over skeletal muscles.
In the ANS, motor neurones of the CNS synapse onto visceral motor neurones in autonomic ganglia, and these ganglionic neurones control visceral effectors.
30
What is the ANS divided into?
ANS innervation is divided into:
- sympathetic nervous system
- parasympathetic nervous system divisions.
31
What do the sympathetic and parasympathetic divisions of the ANS control?
Two divisions usually have opposing effects, but not always. Sometimes they control different parts of complex processes.
- Sympathetic division usually only 'kicks in' during periods of exertion, stress or emergency.
- Parasympathetic division predominates under resting conditions.
32
What are the alternative names for sympathetic and parasympathetic divisions, and why?
Sympathetic division is also called the thoracolumbar division: neurons begin at the thoracic and lumbar (T1-L2) portions of the spinal cord.
Parasympathetic division also called the craniosacral division: neurons begin at the cranial nerves (CN 3, CN7, CN 9, CN10) and sacral (S2-S4) spinal cord.
33
In what 2 main ways does the ANS exert control over visceral effectors?
- The sympathetic division can change the activities of tissues and organs by releasing NE at peripheral synapses, and by distributing E and NE throughout the body in the bloodstream.
- The visceral motor fibres that target specific effectors, such as smooth muscles in blood vessels can be activated in reflexes that do not involve other visceral effectors. In a crisis however the entire division responds.
34
What changes does a person experience with sympathetic activation? (6)
- Increased alertness via stimulation of the reticular activating system, causing the individual to feel on edge.
- A feeling of energy and euphoria, often associated with a disregard for danger.
- a temporary insensitivity to painful stimuli
- Increased activity in the CV and respiratory centres of the pons and the medulla oblongata, leading to elevation in blood pressure, heart rate, beating rate and depth of respiration
- A general elevation in muscle tone, so the person looks tense and may begin to shiver.
- The mobilisation of energy reserves throug the accelerated breakdown of glycogen in muscle and liver cells and the release of lipids by adipose tissue
35
What parts of the nervous system does sympathetic activation stimulate, and what is it controlled by?
This event called sympathetic activation is controlled by sympathetic centres in the hypothalamus. The effects are not limited to peripheral tissues, sympathetic activation also alters CNS activity.
36
What changes specific to promoting fight or flight occur with sympathetic activation? (8)
- Diverts blood flow away from the gastro-intestinal (GI) tract and skin via vasoconstriction.
- Blood flow to skeletal muscles and the lungs is enhanced (by as much as 1200% in the case of skeletal muscles).
- Dilates bronchioles of the lung, which allows for greater alveolar oxygen exchange.
- Increases heart rate and the contractility of cardiac cells (myocytes), thereby enhancing blood flow to skeletal muscles.
- Dilates pupils and relaxes the ciliary muscle to the lens, allowing more light to enter the eye and far vision.
- Provides vasodilation for the coronary vessels of the heart.
- Constricts all the intestinal sphincters and the urinary sphincter.
- Inhibits peristalsis.
37
What does the stimulation of the parasympathetic nervous system do?
- Promotes a "rest and digest" response, promotes calming of the nerves return to regular function, and enhances digestion.
- Dilates blood vessels leading to the GI tract, increasing blood flow. This is important following the consumption of food, due to the greater metabolic demands placed on the body by the gut.
- Constricts the bronchiolar diameter when the need for oxygen has diminished.
- Constriction of the pupil and contraction of the ciliary muscle to the lens, allowing for closer vision.
- Salivary gland secretion, and accelerates peristalsis so it mediates digestion of food and indirectly, the absorption of nutrients.
- Erection of genitals, via the pelvic splanchnic nerves 2–4.
- Stimulates sexual arousal
38
What is another name for the bystander effect?
What is the probability of receiving help inversely proportional to?
Genovese syndrome
The probability of help has in the past been thought to be inversely related to the number of bystanders; in other words, the greater the number of bystanders, the less likely it is that any one of them will help.
39
What is the link between the bystander effect and whether bystanders are friends of the victim?
increasing group size inhibited intervention in a street violence scenario when bystanders were strangers but encouraged intervention when bystanders were friends.
40
What are the two main reasons that bystanders do not help?
- The principal of social influence: bystanders monitor the reactions of other people in an emergency situation to see if others think that it is necessary to intervene. Since everyone is doing exactly the same thing (nothing), they all conclude from the inaction of others that help is not needed. This is an example of pluralistic ignorance or social proof.
- Diffusion of responsibility. This occurs when observers all assume that someone else is going to intervene and so each individual feels less responsible and refrains from doing anything.
41
What type of person would be (quite surprisingly) the least likely to help in an emergency situation?
Highly masculine subjects were less likely to take action to help the victim than were other subjects. Femininity and actual gender had no effect on likelihood of helping. Results suggests that highly masculine subjects fear potential embarrassment and loss of poise, so they may be reluctant to intervene in emergencies.
42
How does the perceived danger of a situation affect the bystander effect?
The bystander is more likely to help if the situation is perceived as dangerous (compared with non-dangerous), perpetrators were present (compared with non-present), and the costs of intervention were physical (compared with non-physical).
Consistent with the arousal-cost-reward model, which proposes that dangerous emergencies are recognized faster and more clearly as real emergencies, thereby inducing higher levels of arousal and hence more helping
43
What do you use to manage an acute trauma case?
ATLS protocol
44
What are the main components of ATLS protocol?
Primary Survey
A - airway with cervical spine support
B - Breathing and Ventilation
C - Circulation and haemorrhage control
D - Disability, neurological check
E - Exposure
Secondary Survey
45
Describe the primary survey of the ATLS protocol
The first and key part of the assessment of patients presenting with trauma is called the primary survey. During this time, life-threatening injuries are identified and simultaneously resuscitation is begun. A simple mnemonic, ABCDE, is used as a memory aid for the order in which problems should be addressed.
46
Describe the airway check of the primary survey of the ATLS protocol
- The first stage of the primary survey is to assess the airway. If the patient is able to talk, the airway is likely to be clear. If the patient is unconscious, he/she may not be able to maintain his/her own airway.
- The airway can be opened using a chin lift or jaw thrust. Airway adjuncts may be required.
- If the airway is blocked (e.g., by blood or vomit), the fluid must be cleaned out of the patient's mouth by the help of sucking instruments. In case of obstruction, pass an endotrachial tube.
47
Describe the breathing and ventilation check of the primary survey of the ATLS protocol
The chest must be examined by inspection, palpation, percussion and auscultation. Subcutaneous emphysema and tracheal deviation must be identified if present. The aim is to identify and manage six life threatening thoracic conditions
Airway Obstruction
Tension Pneumothorax
Massive Haemothorax
Open Pneumothorax
Flail chest segment with Pulmonary Contusion
Cardiac Tamponade
48
Describe the circulation check of the primary survey of the ATLS protocol
Hemorrhage is the predominant cause of preventable post-injury deaths. Hypovolemic shock is caused by significant blood loss. Two large-bore intravenous lines are established and crystalloid solution given. If the patient does not respond to this, type-specific blood, or O-negative if this is not available, should be given. External bleeding is controlled by direct pressure. Occult blood loss may be into the chest, abdomen, pelvis or from the long bones.
49
Describe the disability check of the primary survey of the ATLS protocol
- A basic neurological assessment is made, known by the mnenomic AVPU (alert, verbal stimuli response, painful stimuli response, or unresponsive).
- The Glasgow Coma Scale is a quick method to determine consciousness, and is predictive of patient outcome. If not done in the primary survey, it should be performed as part of the secondary survey.
- An altered level of consciousness indicates the need for immediate reevaluation of the patient's oxygenation, ventilation, and perfusion status. Hypoglycemia and drugs, including alcohol, may influence the level of consciousness. If these are excluded, changes in consciousness should be considered due to traumatic brain injury until proven otherwise.
50
Describe the exposure check of the primary survey of the ATLS protocol
The patient should be completely undressed, usually by cutting off the garments. It is imperative to cover the patient with warm blankets to prevent hypothermia in the emergency department. Intravenous fluids should be warmed and a warm environment maintained. Patient privacy should be maintained
51
Describe the secondary survey in the ATLS protocol
When the patient is stabilised, the secondary survey is a head-to-toe evaluation of the trauma patient, including a complete history and physical examination, including the reassessment of all vital signs. X-rays indicated by examination are obtained. If at any time during the secondary survey the patient deteriorates, another primary survey is carried out as a potential life threat may be present. The person should be removed from the hard spine board and placed on a firm mattress as soon as reasonably feasible as the spine board can rapidly cause skin breakdown and pain while a firm mattress provides equivalent stability for potential spinal fractures
52
What is intrapleural pressure, and what 3 things is it caused by?
Intrapleural pressure, or Ppl, is the pressure surrounding the lung, within the pleural space. Pleural pressure is always negative; that is, it is below atmospheric pressure. This negative pressure acts to keep the lung inflated.
This negative pressure is caused by 3 things:
- Surface tension of alveolar fluid.
- Elasticity of the lung.
- Elasticity of the thoracic wall
53
What does pleural fluid do?
The pleural space is filled with pleural fluid;
- The pleural fluid assists in breathing by acting as a lubricant
- the surface tension of this fluid prevents the two pleural membranes from separating entirely as forces pull them in opposite directions.
54
Describe the changes in pleural pressure during breathing
At full expiration, the pleural space is about -4mm Hg (4 mm of mercury below atm pressure)
At the lungs inspire, the intrapleural pressure drops to -6mm Hg. This is due to a slight increase in the volume of the pleural space as the thoracic wall pulls the parietal pleura outwards.
As the intrapleural pressure decreases, the difference between lung pressure and pleural pressure (the transpulmonary pressure) increases, causing the lung to inflate.
55
Describe inspiration in terms of movement and pressure changes. (6 stages)
Volume of thoracic cavity increases
The intrapleural pressure becomes more negative
Which increases the transpulmonary pressure
Which causes the lungs to expand
Intrapulmonary pressure lowers to below atmospheric pressure
Air following its pressure gradient flows into the lungs
56
Describe expiration in terms of movement and pressure changes.
Volume of thoracic cavity decreases
The intrapleural pressure becomes less negative
So the transpulmonary pressure decrease
Which causes the lungs to recoil
The intrapulmonary pressure increases to above atmospheric pressure
Air following its pressure gradient flows out of the lungs
57
Which part of the lung is usually most compliant and why?
The bottom of the lung is most compliant
- As a result of gravity, in an upright individual the pleural pressure at the base of the lung base is less negative than at its apex; when the individual lies on his back, the pleural pressure becomes greatest along his back.
- Since alveolar pressure is uniform throughout the lung, the top of the lung generally experiences a greater transpulmonary pressure and is therefore more expanded and less compliant than the bottom of the lung.
58
How can forced expiration cause limitation of air flow?
During active expiration, the abdominal muscles are contracted to force up the diaphragm and the resulting pleural pressure can become positive. Positive pleural pressure may temporarily collapse the bronchi and cause limitation of air flow.
59
Describe breathing in at rest, including the muscles used.
Contraction of the Intercostal muscles lifts the rib cage upwards and outwards, increasing the thoracic volume. Contraction of the diaphragm causes the diaphragm to flatten, which also increases the thoracic volume. As the volume of the lungs increases, the pressure inside them decreases to below atmospheric pressure. Environmental air then follows its pressure gradient down to fill the lungs
60
Describe breathing out at rest including the muscles
Relaxation of the diaphragm causes the diaphragm to become more dome shaped. This decreases the volume of the thoracic cavity and compresses the lungs. The external intercostal muscles also relax, moving the ribcage downwards and inwards, further decreasing the volume of the thoracic cavity. As the volume of the lungs decreases, the pressure in the lungs increases to above atmospheric pressure. With a pathway to the mouth or nose clear, this increased pressure forces air out of the lungs.
61
Describe breathing in deeply including muscles used.
The diaphragm and external intercostal muscles contract more forcefully than during quiet breathing.
Sternocleidomastoid and Scalenes muscles also contract to pull the rip cage higher
These actions further increase the volume of the thoracic cavity
62
Describe breathing out deeply including muscles used
```
Unlike breathing out at rest, this is an active process requiring the contraction of several muscles
Internal intercostal muscles contract and move the rib cage downwards and inwards
Abdominal muscles (the external obliques, internal obliques, rectus abdominus and transverse abdominus) compress the abdominal organs, forcing them upwards to push against the diaphragm.
```
63
Describe the changes in the pressure in the lungs during breathing
Between breaths, intrapulmonary pressure = atmospheric pressure = 760mmHg.
When talking about pressures during breathing this pressure is usually referred to as 0.
- During inspiration, intrapulmonary pressure drops below atmospheric pressure
- During expiration, intrapulmonary pressure rises above atmospheric pressure
64
What are the four main centers in the brain to regulate the respiration?
There are four main centers in the brain to regulate the respiration:
1. Inspiratory center
2. Expiratory center
3. Pneumotaxic center
4. Apneustic center
65
Where is each of the four centres of the brain that control respiration?
1. Inspiratory center - medulla oblongata
2. Expiratory center - medulla oblongata
3. Pneumotaxic center - the pons
4. Apneustic center - the pons
66
What is airway obstruction and how do you diagnose it?
Airway obstruction: increased resistance in the bronchioles (usually from a decreased radius of the bronchioles) that reduces the amount of air inhaled in each breath.
Obstruction can be measured using spirometry. A decreased FEV1/FVC ratio (versus the normal of about 80%) is indicative of an airway obstruction. An airway restriction would not produce a reduced FEV1/FVC ratio, it would produce a reduced vital capacity only.
67
What is a massive haemothorax?
Haemothorax: blood accumulating in the pleural cavity.
Cause is usually traumatic, blood spills into the pleural space, equalizing the pressures between it and the lungs.
Blood loss may be massive in people with these conditions, as each side of the thorax can hold 30–40% of a person's blood volume. Even minor injury to the chest wall can lead to significant hemothorax.
The condition can progress to a point where the blood accumulation begins to put pressure on the mediastinum and the trachea, effectively limiting the amount that the heart's ventricles are able to fill. The condition can cause the trachea to deviate, or move, toward the unaffected side.
68
How do you manage massive haemothorax?
Thoracostomy (chest tube to drain blood): Usually the lung will expand and the bleeding will stop after a chest tube is inserted.
The blood can clot in the pleural space (retained hemothorax) or clog the chest tube, worsening the retained haemothorax. In this case, patients can be hypoxic, short of breath, or the retained haemothorax can become infected (empyema).
To minimise clogging, the surgeons will often place more than one tube, or large diameter tubes.
Thrombolytic agents have been used to break up clots, however this is risky as it can lead to increased bleeding.
In some cases bleeding continues and surgery is necessary to stop the source of bleeding.
69
What is haemopneumothorax and how do you treat it?
Haemopneumothorax: the combination of pneumothorax and hemothorax.
If the chest wall, and thus the pleural space, is punctured, blood, air or both can enter the pleural space to equalise the pressure with that of the atmosphere. The affected lung collapses.
Treatment for this condition is again by tube thoracostomy, the insertion of a chest drain through an incision made between the ribs, into the intercostal space
70
What is a flail chest?
A flail chest is a life-threatening medical condition that occurs when a segment of the rib cage breaks under extreme stress and becomes detached from the rest of the chest wall. It occurs when multiple adjacent ribs are broken in multiple places, separating a segment, so a part of the chest wall moves independently.
71
What is cardiac tamponade?
How does the amount of time over which it occurs affect it?
What are its causes? (5)
Cardiac tamponade: aka pericardial tamponade: Cardiac tamponade is pressure on the heart muscle which occurs when the pericardial space fills up with fluid. If the amount of fluid increases slowly (eg hypothyroidism) the pericardial sac can expand to contain a liter or more of fluid prior to tamponade occurring. If the fluid occurs rapidly (eg trauma or myocardial rupture) as little as 100 ml can cause tamponade.
Causes of increased pericardial effusion include hypothyroidism, myocardial rupture, penetrating trauma, blunt chest trauma, pericarditis (inflamed pericardium).
72
How do you diagnose cardiac tamponade?
Differential diagnoses include tension pneumothorax, and acute heart failure.
In a trauma patient presenting with PEA (pulseless electrical activity) in the absence of hypovolemia and tension pneumothorax, the most likely diagnosis is cardiac tamponade.
Signs of classical cardiac tamponade include three signs, known as Beck's triad.
- Hypotension occurs because of decreased stroke volume
- Jugular-venous distension due to impaired venous return to the heart
- Muffled heart sounds due to fluid inside the pericardium
73
What is the immediate first aid treatment for a sucking chest wound?
- It can be difficult to identify when a penetrating wound to the chest is sucking air or not, so assume any penetrating wound to the chest is a sucking chest wound.
- Seal the sucking chest wound by taping a dressing over it. Taping on 3 sides is meant to help air from going in while letting extra air out.
- Watch for signs of tension pneumothorax
74
What is the typical radiation dose to an adult from CXR?
The typical radiation dose to an adult from CXR is around 0.06 mSv.
75
What do the colours on an x-ray relate to?
What type of tissue appears white? What is the name for this?
What type of tissue appears dark? What is the name for this?
Difference in colour relate to the density of tissues
Tissues that are DENSE absorb many X-rays and appear WHITE on the film (radiopaque)
Tissues that are LESS DENSE let more X-rays through and appear DARK (radiolucent)
76
What are the 5 main colours seen on an X-ray and what tissues/materials do they relate to?
Gas/air - black
Fat - dark grey
Soft tissues/water - light gray
Bone - white
Metal/contrast material - bright white
77
What are the 6 stages you work through each time you read an X-ray?
10 Second stare
A. Adequacy, alignment, apparatus
B. bones
C. Cartilage and joints
S. soft tissue: central lateral and peripheral
P. Pitfall (missed areas)
78
Describe the initial view of a CXR
The first thing to check on a CXR is that the patient details, date are correct and that you are looking at the latest X-ray.
Then check whether it's an AP or PA view
10 second stare to look for any gross abnormalities or asymmetry
79
Describe the A stage of assessing a CXR
ADEQUACY: refers to exposure of the film and the area of the chest that can be viewed. Correct exposure: you can see the vertebral bodies through the heart shadow.
Can you see: all the thorax, apices of lungs, left and right costodiaphragmatic recesses?
Inspiration: degree of inspiration: the right side of the diaphragm should be in line with the front end of the 6th rib or the back end of the 9th 10th rib.
ALIGNMENT
Check there is no rotation of the patient. The sternoclavicular joints should each be the same distance from the vertebral spines.
If there is rotation there will be distortion of the mediastinal contours and inequality in the transradiency (blackness) of each half of the thorax.
APPARATUS: Check that all lines etc are in the right place
80
Describe the B stage of assessing a CXR
BONES
Check bone shape, Look for changes in density or any fractures, Compare both sides
Ribs: trace trace each rib in order from the top down. Start posteriorly at the costotransverse joint and follow the rib around anteriorly to the midclavicular line where it joins the costal cartilage. Note the costal cartilage will not be visible unless it is calcified.
Vertebrae: some vertebrae but not all will be visible. Inspect all those that are visible. The spinous process should be seen in the middle.
Check: Clavicles, Scapulae, Humeri: check the proximal part of each humerus
81
Describe the C stage of the assessment of a CXR
CARTILAGE and JOINTS
Compare the glenohumeral joints. Do they look the same
82
Describe the S stage of the assessment of a CXR
SOFT TISSUES
Central: mediastinum - upper middle and lower
Lateral: the lungs
Peripheral: includes chest wall, diaphragm and below the diaphragm.
83
Describe the P stage of assessing a CXR
4 PITFALL AREAS:
The lung apices
Behind the heart shadow
Under the diaphragm
Peripheral soft tissue and breast shadows
84
Which is the most common X-ray view? Describe it
Posteroanterior (PA) view: x-rays enter through the posterior (back) aspect of the chest, and exit out of the anterior (front) aspect where they are detected. Exposure is taken at full inspiration with the X-ray source located 2m behind the patient
85
Which CXR view do you use if the patient is unable to stand?
Anteroposterior (AP) views: x-rays enter through the anterior aspect and exit through the posterior aspect of the chest. AP chest x-rays are harder to interpret than PA x-rays and are therefore generally reserved for situations where it is difficult for the patient to obtain a normal chest x-ray, such as when the patient cannot get out of bed. In this situation, mobile X-ray equipment is used. The patient either sits (AP erect) or lies (AP supine). As a result most supine films are also AP.
86
What medication might you prescribe for PTSD? (4)
When do you give them?
paroxetine, an selective serotonin reuptake inhibitors (SSRIs)
mirtazapine, an antidepressant.
Amitriptyline or phenelzine
However, these medications should only be used when:
- the person chooses not to have trauma-focused psychological treatment,
- the person cannot start psychological treatment due to a high risk of further trauma,
- the person has gained little or no benefit from a course of trauma-focused psychological treatment
- there is severe depression or hypersensitivity.
87
How can abuse in childhood affect PTSD in later life?
child abuse may interact with mutations in a stress-related gene to increase the risk of PTSD in adults.
88
Which Three areas of the Brain have been associated with PTSD
Three areas of the brain whose function may be altered in PTSD have been identified:
prefrontal cortex,
amygdala processes fear
hippocampus codifies information
89
Describe the pathway of the neurones of the ANS
- Visceral motor neurones with their nuclei in the hypothalamus form the centres for autonomic activity.
- These neurones run from the hypothalamus to enter the brain stem or spinal cord, where they synapse with preganglionic neurones.
- Preganglionic neurones are mostly involved in reflex arcs. Their nuclei are located in teh brain stem or spinal cord.
- The axons of preganglionic neurones are caled preganglionoc fibres. Preganglionic fibres leave the brain stem or spinal cord and synapse onto ganglionic neurones, which have their nuclei in the peripheral ganglia.
- Ganglionic neurones innvervate visceral effectors
- The axons of ganglionic neurones are called postganglionic fibres
90
What is Thoracentesis?
Also called a pleural fluid tap, this procedure involves aspiration of fluid from the pleural space using a long, thin needle inserted between the ribs
91
What are the 4 physical areas of the brain involved in respiration control?
* medulla (reticular formation)
* ventral respiratory group: controls voluntary forced exhalation and acts to increase the force of inspiration.
* dorsal respiratory group: controls mostly inspiratory movements and their timing.
* pons
92
What does the Pneumotaxic center do? (3)
* Coordinates transition between inhalation and exhalation
* Sends inhibitory impulses to the inspiratory area
* involved in fine tuning of respiration rate.
93
What does the Apneustic center do? (2) What is it overridden by?
* Coordinates transition between inhalation and exhalation
* Sends stimulatory impulses to the inspiratory area – activates and prolongs inhalation (long deep breaths)
* Overridden by pneumotaxic control to end inspiration.
94
What is ventilatory rate primarily determined by?
Ventilatory rate (minute volume) is tightly controlled and determined primarily by blood levels of carbon dioxide (as determined by metabolic rate.) Blood levels of oxygen become important in hypoxia.
95
Where are the chemoreceptors for pH, oxygen and carbon dioxide?
.
* medulla oblongata for pH
* carotid and aortic bodies for oxygen and carbon dioxide
96
Why does blood Co2 usually rise?
Levels of CO2 rise in the blood when the metabolic use of O2 is increased beyond the capacity of the lungs to expel CO2.
97
Explain how a build up of CO2 decreases the pH of the blood, including what the CO2 is converted into
* CO2 is stored largely in the blood as bicarbonate (HCO3-) ions, by conversion first to carbonic acid (H2CO3), by the enzyme carbonic anhydrase, and then by disassociation to H+ and HCO3-.
* Build-up of CO2 therefore causes an equivalent build-up of the disassociated hydrogen ion.
98
* What does ventilation rate increase in response to during moderate excersise?
* What does ventilation rate increase in response to during strenuous excersise?
* During moderate exercise, ventilation increases in proportion to metabolic production of carbon dioxide.
* During strenuous exercise, ventilation increases more than needed to compensate for carbon dioxide production. Lactate produced during anaerobic metabolism lowers pH and thus increases breathing.
99
What effect on pH does anaerobic respiration have and why?
Anaerobic respiration reduces pH faster than aerobic respiration.
In aerobic metabolism, one molecule of acid (CO2) is produced in order to produce 6 molecules of the energy carrier ATP, whereas in anaerobic metabolism, 6 molecules of lactate are produced to provide the same amount of energy.
100
What effects do opioids and amphetamines have on respiration?
Opioids and anaesthetic drugs tend to depress ventilation, especially with regards to Carbon Dioxide response.
Stimulants such as Amphetamines can cause hyperventilation.
101
What effects does pregnancy have on respiration? Why?
Pregnancy tends to increase ventilation (lowering plasma carbon dioxide tension below normal values). This is due to increased progesterone levels and results in enhanced gas exchange in the placenta.
102
Where are ventilatory mechanoreceptors found, and what is their role?
* Mechanoreceptors are located in the airways and parenchyma, and are responsible for a variety of reflex responses:
* The Hering-Breuer reflex that terminates inspiration to prevent over inflation of the lungs, and the reflex responses of coughing, airway constriction, and hyperventilation.
* The upper airway receptors are responsible for reflex responses such as, sneezing, coughing, closure of glottis, and hiccups.
103
How do reflexes that go through the spinal cord affect ventilation? (4)
The spinal cord reflex responses include the activation of additional respiratory muscles as compensation, gasping response, hypoventilation, and an increase in breathing frequency and volume.
104
How can nerve impulses from the nasal mucosa affect ventilation?
The nasopulmonary and nasothoracic reflexes regulate the mechanism of breathing through deepening the inhalation. Triggered by the flow of the air, the pressure of the air in the nose, and the quality of the air, impulses from the nasal mucosa are transmitted by the trigeminal nerve to the breathing centres in the brainstem, and the generated response is transmitted to the bronchi, the intercostal muscles and the diaphragm.
105
What areas of the brain other than the respiratory centres can affect ventilation, and in what circumstances? (3)
In addition to involuntary control of respiration by the respiratory center, respiration can be affected by conditions such as emotional state, via input from the limbic system, or temperature, via the hypothalamus. Voluntary control of respiration is provided via the cerebral cortex, although chemoreceptor reflex is capable of overriding conscious control
