Anaesthetics & Emergency Medicine Notes PDF

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POEM Michael Grant

Notes based on QUB online Med Portal lectures, QUB student manual, NICE Guidelines, Oxford Clinical handbook and various external online resources

POEM: Page 2 of 68

LEARNING OUTCOMES 2014-2015 Airway Management

Cricothyroid membrane Location of insertion of surgical airway

Airway

The upper airway or the upper respiratory system consists of the nose, oral cavity, and pharynx (itself further divided into nasopharynx, oropharynx and laryngopharynx), while the lower respiratory system describes everything below the vocal cords (Tracheobronchial tree)

. It is important to remember to ; but

LOOK

.

LISTEN

FEEL

*

• • • •

• • PNS disorder (Recurrrent Laryngeal n. palsy, hypocalcaemia) Neuromuscular disorders (laryngospasm, myasthenia gravis)

•

(allergy, hereditary angioedema)

• • •

Neoplasm (upper airway cancer, vocal polyp)

If patient can talk airway is patent !!!

In patients who are the commonest cause is due to The usual site of obstruction is the soft palate, followed by the epiglottis and occasionally the tongue. Fingers on both sides of mandible

HEAD TILT AND CHIN LIFT OR JAW THRUST

This tenses muscles in the mouth floor causing the hyoid & larynx to be lifted away from the post. pharyngeal wall. If unconscious but breathing, consider putting patient into the recovery position.

The commonest cause of airway obstruction is loss of airway muscle tone

Michael Grant

Adjuncts are used to secure the airway once the airway has been opened by either a head-tilt and chin-lift or jaw-thrust manoeuvre

Airway adjuncts

Always remember to put gloves on first! POEM: Page 3 of 68

• •

Prevents tongue from obstructing the airway Unconscious patients Can simulate a powerful gag reflex

• • •

Adjuncts •

o o o The airway is inserted upside down until contact is made with the back of the o throat, then rotated 180 Bypasses airway obstruction via the nose Intact gag reflex

Beware of heavy nasal bleeding - Do not use in people with anticoagulants

• • •

Advantages over the oropharyngeal airway as

• • •

Use a small amount of

o o

and with gentle but firm pressure direct backwards and downwards

Ensure that bevel faces the septum to protect structures as NPA passes through the nasal cavity Typically inserted into the right nostril, hence when the bevel is facing the septum in this nostril the curve in the NPA follows the airway – so if inserting into the left, face bevel to septum then rotate 180 degrees when tip of NPA reaches back of nasal caviy

•

MUST KNOW LMA FOR OSCE !!! Supraglottic device Sits in patient's hypopharynx and covers the supraglottis

• •

that was developed by a British Anaesthetist called Dr Archie Brain in the 80’s to free the hands of the provider with the benefit of less gastric distension.

•

• o

•

Cuff volume (Size - 1) x 10

Sizes are written on the side of the device Once inserted, you can let go, you don't have to hold airway

Weight (kg)

Size (of LMA)

hip binders) 3. Rectal exam: Perianal sensation, anal tone Co-ordinatior says “Roll back to bed on 3, 1... 2... 3”

KNOW C-SPINE MANAGEMENT FOR OSCE !!!

Logroll method

Michael Grant

LEARN !!!

Tracheostomy and Laryngectomy

POEM: Page 6 of 68

Tracheostomy Emergencies The creation of a stoma into the trachea (trache-ostomy) serves several functions in the intensive care unit: • • •

There are two types of Neck Breathers: 1. Post Laryngectomy patients (obligate neck breathers) RED SIGNS: • These people cannot be intubated via the mouth 2. Post Tracheostomy patients (larynx Intact) GREEN SIGNS: • These people may be intubated via the mouth as they may still have a patent upper airway – but intubation may be difficult Laryngectomy =

No mouth (No patent airway) Tracheostomy = Can mouth (Patent airway)

The management of these patients differ.

. For this reason, the National Tracheostomy Safety Project publish a seperate algorithm that is in red (as seen on the left) for laryngectomy patients and green for tracheostomy patients (seen on right) All patients with a tracheostomy should have a sign above their bed detailing the type of tracheostomy they have.

1. 2. Most tracheostomies are and are inserted by skilled anaesthetists, • These stomas do not maintain their patency if the cannula is displaced and the stoma shrinks • They must be securely taped in place and any concerns regarding a dislodged tracheostomy you must contact the anaesthesia team

LEARN !!!

Tracheostomy

POEM: Page 7 of 68

Cannula used as an airway The inner cannula in these devices serve as a simple means of maintaining a patient airway as the inner cannula is replaced as mucus and secretions accumulate. You need to be aware that to connect the 'tracheotwist' double cannula tracheostomy to a bag, valve and mask the inner cannula must remain in situ.

This is important information when faced with a blocked tracheostomy. By deflating the cuff there may now be a space for some air to move buying time until the anaesthesia team arrive. If faced with a bleeding tracheostomy ensure the cuff is well inflated as this may tamponade the source. Remove all valves and caps when faced with an emergency situation.

Obstructed tracheostomy Mx 1. Apply the we have adopted for all patients and determine if the tracheostomy is still patent. o

2. If the tracheostomy is not patent, if present. 3. Attempt to pass a through the tracheostomy, as this will determine if patentcy and will help to that may have accumulated 4. If you cannot pass the catheter, if there is one and at the mouth and nose o Is there occurring at this site now that the cuff has been deflated? If yes, here and wait for the anaesthesia team 5. If the airway is still not obtained after these measures, o Deflate the cuff and take it out o Immediately reassess the patient and where you determine ventilation is occurring (Mouth or tracheostomy site). This is an y and the anaesthesia team should be en route. o While waiting, . Obstruction can often be prevented if there is for new tracheostomies. Proper constant humidification should prevent secretion blockage o as a substitute as they actually make the situation worse.

Dislodged tracheostomy Mx 1.

you use for all patients while the anaesthesia team is summoned. Keep calm and ? Is the ? If , safest to reinsert under controlled conditions for the anaesthesia team

o 2. o

Assess using the .

and

Michael Grant

Bleeding Tracheostomy Mx can be controlled by: • summoned. • will require a surgeon to

) with or without

. Minor bleeding while help is l, the patient will then be

Breathing

KNOW Fi02 VALUES FOR MCQs !!!

•

Patients can feel claustrophobic !!!

•

The FiO2 delivered is variable and depends on the flow of Oxygen and the patient’s respiratory pattern

•

Breathing through nose or mouth does not appear to influence the FiO2 Hudson Facemask: greatly but it is preferential for them to expire through the mouth so as not - Flow Rate: 4-15 l/min to lose the nasopharynx reservoir of oxygen - FiO2: 0.35 - 0.6 It is a clear plastic face-mask that is placed over the nose and mouth of a patient, the FiO2 delivered is variable but at max flow rates of 15LPM with FiO2 up to 0.6. The range of FiO2 is often described as 0.35-0.6 and again is dependent on the patient’s respiratory mechanics and the flow rate set (415LPM.) The disadvantages of the mask are that patient compliance can be low as after time the mask becomes claustrophobic, prevents the patient from eating, drinking or speaking freely. A Tracheostomy Mask is a variation with all the features mentioned for the Hudson facemask but has been designed to fit around a tracheostomy site.

•

• •

Ideal for claustrophobic patients and for those on long-term oxygen therapy

•

Nasal Cannula: - Flow rate: 2-4 l/min (6 l/min) - FiO2: 0.24-0.36 (0.44)

• •

•

• • •

They work principally by utilising the dead space of the nasopharynx as a reservoir for oxygen, when the patient inspires, the air entrained mixes with the reservoir oxygen and the inspired gas is enriched. FiO2 possible with nasal cannula varies generally from 0.24 - 0.36. Some texts describe a maximal FiO2 of 0.44 at flow rates of 6LPM (which most patients find extremely uncomfortable) Higher flow rates only cause turbulence in the tubing and cannot increase the FiO2 any further The normal flow rates used are usually 2-4LPM, patients find this comfortable and advantages are they are able to eat, drink and talk normally. The disadvantages are that the cannulae can be easily displaced by the patient, they cause nasal passage drying and crusting and occasionally nose bleeds. May cause nasal passage drying, nasal crusting, and nose bleeds Michael Grant

ALWAYS REACH FOR THIS FIRST IN A SICK PATIENT !!!

When the patient expires the one-way valve will close preventing any expire CO2 entering the reservoir bag thereby preventing rebreathing Patients can feel claustrophobic !!! •

e 9 of 68 Non-Rebreather Mask Flow Rate: 10-15 l/min FiO2: 0.6 - 0.85

•

When the patient expires the one-way valve will close preventing any expired CO2 entering the reservoir bag thereby preventing rebreathing to a certain extent. Some masks also have one way valves on the vents at the side of the mask which close during inspiration to try and prevent entrainment of air. Some entrainment will always occur however as air can leak around the sides of the mask which are often not flush or tightly opposed to the face of the patient At 10-15LPM the range of FiO2 to be expected is 0.6 - 0.85 The disadvantages are similar to those of the Hudson mask.

•

•

• •

• (Converts liquids to aerosols)

•

• •

• • •

The pressure drop and increased velocity of gas flow through a narrowing causes the nebuliser fluid to be broken into droplets that can be inhaled by the patient

Most common nebulisers utilise a baffle within their mechanism that at appropriately set flow rates will create droplets of a size 1-5micrometres ideal for being inhaled to their site of action.

Need to fill up bag with oxygen first!

Nebuliser Mask: - Flow Rate: 4-6 l/min

Gives meds as inhaled gases!

Nebulisers are used to convert liquids into aerosols of a size that can be inhaled into the lower respiratory tract, by a process of atomisation. Nebuliser masks use the Venturi effect, the pressure drop and increased velocity of gas flow through a narrowing is utilised to entrain the nebuliser fluid into the jet stream causing it to be sheared and to break into droplets. The baffle, which is placed within the jet stream further decreases the size of the droplets and returns bigger droplets back to the reservoir of fluid to be aerosolized once more. They are most commonly used in the hospital setting for inhaled bronchodilators but other drugs can be administered through this route. (Adrenaline, Dornase alfa and some antibiotics) The optimal flow rate is 4-6 litres per minute, any lower and you will not aerosolize the liquid to an appropriate size Nebulisers can be driven by oxygen (most common in acute or emergency settings) or medical air (more common in home settings or on some wards)

Know Ambu Bag !

• • • • •

The system typically consists of an oxygen reservoir, a football–size self-expanding bag, a one-way valve, a universal adaptor, and a clear flexible mask. The system can deliver ambient air, but in a hospital setting it should be connected to a supplemental Oxygen supply. The flow rate for this device is 12–15 LPM, which deliver a FiO2 up to 0.8 . The

•

•

Aggressive bagging can lead to increased intra-abdomina pressure which in turn increases intra-thoracic pressure making it more and more difficult to ventilate

Ambu Bag - Flow rate: 12-15 l/min - FiO2 - upto 0.8

Michael Grant

VENTURI FACEMASK

• • •

POEM: Page 10 of 68

Sometimes referred to as systems referring to the fact that they cannot meet the patients inspiratory flow demands (normal flow 25- 30L/min) and therefore additional flow is provided by surrounding room air The room air Fi02 alongside the Oxygen enriched gas and dilutes the mixture The true FiO2 depends on the patients’ respiratory demand. governed by the respiratory rate, the inspiratory flow rate and also the length of expiratory pause, i.e. a patient in respiratory distress, their respiratory demand will far exceed that of normal healthy individuals

•

• •

L E A R N

These deliver a predictable and accurate FiO2

The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. The pressure drop induced by the increase in velocity of a fluid passing through a narrow orifice can be used to entrain air or a nebuliser solution for treating patients.

•

•

Entrain air = Trap air Venturi masks used in CO2 patients

• • • •

The coloured apertures will often state the flow rate required for the FiO2 delivery and it is important to abide by these flow rates to maintain accuracy.

Oxygen tanks are white ! The theoretical maximum oxygen carrying capacity is 1.39 ml O2/g Hb, but direct measurement gives a capacity of 1.34 ml O2/g Hb. is also known as . . It is calculated by: (O2 carried by Hb) + (O2 in solution) = (1.34 x Hb x SpO2 x 0.01) + (0.023 x PaO2)

How to calculate oxygen content of blood

Where: SO2 = percentage saturation of Hb with oxygen Hb = haemoglobin concentration in grams pre 100 ml blood PO2 = partial pressure of oxygen (0.0225 = ml of O2 dissolved per 100 ml plasma per kPa, or 0.003 ml per mmHg)

For CaO2 = 20.1 ml/100 ml and Q = 5 l/min: Oxygen delivery (DO2) = 1005 ml/min

Oxygen delivery

For CvO2 = 15.2

Oxygen Uptake

Michael Grant

POEM: Page 11 of 68

ml/100 ml and Q = 5.0 l/min: Oxygen return = 760 ml/min

The balance between oxygen uptake by the body tissues and oxygen delivery to them is assessed by: • •

The oxygen content of mixed venous blood CvO2, which is normally about 15 ml/100 ml The extraction ratio, which is the ratio of VO2 to DO2 expressed as a percentage. Normally the extraction ratio is about 25% but can double to 50% if tissue demand increases

Both of the above indices are dependant on mixed venous saturation (SvO2), and cardiac output.

• This makes it more difficult for hemoglobin to bind to oxygen (requiring a higher partial pressure of oxygen to achieve the same oxygen saturation), but it makes it easier for the hemoglobin to release oxygen bound to it. The effect of this rightward shift of the curve increases the partial pressure of oxygen in the tissues when it is most needed, such as during exercise, or hemorrhagic shock. • so that hemoglobin binds oxygen more easily, but unloads it more reluctantly. Left shift of the curve is a sign of hemoglobin's increased affinity for oxygen (e.g. at the lungs). Similarly, right shift shows decreased affinity, as would appear with an increase in body temperature, hydrogen ion, 2,3diphosphoglycerate (also known as bisphosphoglycerate) or carbon dioxide concentration •

•

2, 3 DPG interacts with deoxygenated hemoglobin beta subunits by decreasing their affinity for oxygen, so it allosterically promotes the release of the remaining oxygen molecules bound to the hemoglobin, thus enhancing the ability of RBCs to release oxygen near tissues that need it most. 2,3-BPG is thus an allosteric effector.

• • • •

Non-invasive Readily available Easily portable Battery operated

• • •

Is NOT a measure of ventilation Does not measure pulse or CO Risk of burns to patient

•

Time dela

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Poor placement (Same arm as BP cuff) Poor peripheral perfusion Movement (shivering) Coloured nail polish Abnormal haemoglobins • eg. Carboxyhaemoglobin, Methaemoglobin Dyes • e.g.Methylene blue

• • •

Electrical interference Low sats increase 02 demands > stretching of ventricles > reduced contractility > peripheral and pulmonary edema Acute HF can evolve into cardiogenic shock, which is an acute circulatory failure Cardiac tamponade is caused by the accumulation of blood, fluid, pus, clots, or gas in the pericardial space, resulting in reduced ventricular filling and subsequent haemodynamic compromise. Cardiac tamponade is a medical emergency.

•

(Cardiomegaly on CXR) Michael Grant

Pneumothorax Ix: - CXR, CT Scan Mx: - High-flow O2

1 Gram (g) = 1000 Milligrams (mg) 1 Milligram (mg) = 1000 Micrograms (mcg) Acute Asthma Mx: - ABCDE - High-flow O2 through a non-rebreather mask at 15l/min (aim sats 94-98%) - Nebulised Salbutamol 5mg (back-to-back upto 3 times) - Ipratropium Bromide 500 micrograms - Oral Prednisolone 50mg / IV Hydrocortisone 200mg - Magnesium Sulphate IV 2g over 20mins If no response: - IV Salbutamol - IV Aminophylline

Always start with an ABCDE approach Acute COPD Mx - Start on 24-28% oxygen, aim for sats 88-92% - Salbutamol 5mg - Ipratropium Bromide 500 micrograms - IV Hydrocortisone 200mg AND Oral Prednisolone 30mg - Antibiotics if signs of infection - If no response to nebulisers and steroids - IV Aminophylline - Non-invasive positive pressure ventilation (NIPPV) - CPAP

(Primary Pneumothorax) Rim of air 2cm and SOB: Aspirate (2nd ICS, mid-clavicular) - If aspiration fails, consider repe aspiration - If repeat aspiration fails, insertio of chest drain (5th ICS, mid-axillary)

Pulmonary Embolism Ix: Bloods: D-Dimer, ABG ECG: S1Q3T3 pattern Imaging: CXR, CTPA, V/Q Scan Mx: - Oxygen if hypoxic, 10-15l/min - IV Morphine 5-10mg with anti-emetic Anti-coagulation: Clexane - LMWH until PE confirmed Enoxaparin 1.5mg/kg/24h, then Warfarin 10mg, aim INR 2-3 Thrombolysis: - In massive PE, immediate thrombolysis - Alteplase 50mg bolus Surgery: - Embolectomy, IVC filters (prevent recurrence)

(Secondary Pneumothorax) SOB and age > 50y, and rim of a >2cm on CXR

Chronic Heart Failure Mx: 1st line: - ACE-inhibitor & Beta-blocker 2nd line: - Aldosterone antagonist / Angiotensin II receptor blocker / Hydralazine in combination with a Nitrate - Diuretics given if patient fluid congested

Michael Grant

. Respiratory failure is a syndrome in which the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination. In practice, it may be classified as either hypoxemic or hypercapnic. Type I (or hypoxemic) respiratory failure is characterised by an arterial oxygen tension (Pa O2 - the pressure which oxygen would have if it alone occupied the volume) lower than 60mmHg with a normal or low arterial carbo...