Equipment Flashcards
Name the laryngoscope blades
(A) Miller blades (large, adult, infant, premature); (B) Macintosh blades (large, adult, child, baby); (C) Macintosh polio blade; (D) Soper blades (adult, child, baby); (E) left-handed Macintosh blade; (F) Wisconsin blades (large, adult, child, baby, neonate); (G) Robertshaw blades (infant, neonatal); (H) Seward blades (child, baby); (I) Oxford infant blade.
Describe the intended mechanism of use of the Macintosh laryngoscope blade
The Macintosh blade (aka curved blade) is designed to fit into the oral and oropharyngeal cavity. It is inserted through the right angle of the mouth and advanced gradually, pushing the tongue to the left and away from the view until the tip of the blade reaches the vallecula. The blade has a small bulbous tip to help lift the larynx. The laryngoscope is lifted upwards elevating the larynx and allowing the vocal cords to be seen. The Macintosh blade is made in five sizes: neonate (0), infant (1), child (2), adult (3) and large adult (4).
what is the modification/feature on the McCoy laryngoscope?
It has a hinged tip which is operated by the lever mechanism present on the back of the handle. It is suited for both routine use and in cases of difficult intubation. A modified design of the McCoy called the Flexiblade exists, where the whole distal half of the blade can be manoeuvred rather than just the tip. This can be achieved using a lever on the front of the handle.
what is a catheter mount? what is its function?
It has a corrugated disposable plastic tubing. Some catheter mounts have a concertina design allowing their length to be adjusted.
The distal end is connected to either a 15-mm standard tracheal tube connector, usually in the shape of an angle piece, or a 22-mm mask fitting.The proximal end has a 22-mm connector for attachment to the breathing system.
1. The mount minimizes the transmission of accidental movements of the breathing system to the tracheal tube. Repeated movements of the tracheal tube can cause injury to the tracheal mucosa. 2. Some designs allow for suction or the introduction of a fibreoptic bronchoscope. This is done via a special port.
issues-
The catheter mount contributes to the apparatus dead space. This is of particular importance in paediatric anaesthesia. The concertina design allows adjustment of the dead space from 25 to 60 mL.
Foreign bodies can lodge inside the catheter mount causing an unnoticed blockage of the breathing system. To minimize this risk, the catheter mount should remain wrapped in its sterile packaging until needed.
what are variable performance masks?
These masks are used to deliver oxygen-enriched air to the patient. They are also called low-flow delivery devices. They are widely used in the hospital because of greater patient comfort, low cost, simplicity and the ability to manipulate the FiO 2 without changing the appliance. Their performance varies between patients and from breath to breath within the same patient. These systems have a limited reservoir capacity, so in order to function appropriately, the patient must inhale some ambient air to meet the inspiratory demands.
Ambient air is entrained through the holes on both sides of the mask. The holes also allow exhaled gases to be vented out.
During the expiratory pause, the fresh oxygen supplied helps in venting the exhaled gases through the side holes. The body of the mask (acting as a reservoir) is filled with a fresh oxygen supply and is available for the start of the next inspiration.
The final concentration of inspired oxygen depends on:
a. the oxygen supply flow rate b. the pattern of ventilation: If there is a pause between expiration and inspiration, the mask fills with oxygen and a high concentration is available at the start of inspiration c. the patienťs inspiratory flow rate: During inspiration, oxygen is diluted by the air drawn in through the holes when the inspiratory flow rate exceeds the flow of oxygen supply. During normal tidal ventilation, the peak inspiratory flow rate is 20–30 L/min, which is higher than the oxygen supplied to the patient and the oxygen that is contained in the body of the mask, so some ambient air is inhaled to meet the demands thus diluting the fresh oxygen supply. The peak inspiratory flow rate increases further during deep inspiration and during hyperventilation d. how tight the mask fits on the face.
If there is no expiratory pause, alveolar gases may be rebreathed from the mask at the start of inspiration.
The rebreathing of CO 2 from the body of the mask (apparatus dead space of about 100 mL) is usually of little clinical significance in adults but may be a problem in some patients who are not able to compensate by increasing their alveolar ventilation. CO 2 elimination can be improved by increasing the fresh oxygen flow and is inversely related to the minute ventilation. The rebreathing is also increased when the mask body is large and when the resistance to flow from the side holes is high (when the mask is a good fit). The patients may experience a sense of warmth and humidity, indicating significant rebreathing.
A typical example of 4 L/min of oxygen flow delivers an FiO 2 of about 0.35–0.4 providing there is a normal respiratory pattern.
what are venturi masks?
These masks are fixed performance devices (sometimes called high-air-flow oxygen enrichment , or HAFOE).
They deliver a specific oxygen concentration according to the colour used:
Colour FiO 2 (%)
Blue 24
White 28
Yellow 35
Red 40
Green 60
