MasterPass PHYSICS 6

Self-protecting maneuvers do not come into play.

Equivalent to two twitches on to fade.

At 940 nm.

0.2 ms.

Extrapolated.

From a nomogram based on age, height, and weight, or measured in some devices.

Transoesophageal Doppler.

Mobilizes presynaptic acetylcholine, making it available for contractions in response to post-tetanic count.

To measure the percentage of arterial hemoglobin in the blood that is saturated with oxygen.

The simplest form of ultrasound imaging that emits a single ultrasound wave to scan a line through the body, plotting echoes as a function of depth.

Over 10,000 ACh molecules.

660 nm (red light) and 940 nm (infrared light).

Reduced twitch height, no post-tetanic facilitation, and TOF ratio >70%.

Light amplification by the stimulated emission of radiation.

A phenomenon where sound waves reflected from a moving target have a different frequency than the incident sound wave, commonly observed with moving vehicles.

Relatively inexpensive, widely available, non-invasive, and safe in children and pregnancy due to no ionizing radiation.

Operator dependent, cannot image lung, bone, or deep structures.

No, they do not affect readings.

The number of twitches is inversely proportional to the degree of receptor blockade.

'MR conditional' infusion pumps.

'Spiral' scanning is quicker and reduces motion artefact.

Items are safe under certain tested magnetic conditions, which are specified on the product.

Carbon monoxide poisoning and cyanide poisoning.

It irreversibly binds to haemoglobin, leading to falsely high saturation readings.

Transparent tissues like aqueous humour, vitreous humour, and lens of the eye.

By measuring red blood cell velocity in the descending thoracic aorta.

Blood flow.

The phenomenon of decreasing twitch height when competitive neuromuscular blocking drugs are present at the neuromuscular junction.

10.6 μm (infrared region).

They align in the direction of the field.

Beer-Lambert law.

The concentration of the solution and the path-length of light traveling through the solution.

Computed Tomography.

Slice.

By taking a series of X-ray images around a central axis.

Also known as 2D mode, it emits a linear array of ultrasound waves to produce a two-dimensional cross-sectional view, with echo intensity determining the brightness of the image.

A substantial increase in ACh release following tetanic stimulation, which helps overcome competition from NMBDs.

T1 and T2 weighted images.

By shining light through the patient and detecting the amount of light absorbed by oxyhemoglobin and deoxyhemoglobin.

A mode that emits a rapid sequence of ultrasound waves to visualize real-time movement of structures, commonly used in echocardiography.

Superficial surgery, such as dermabrasion and laser facelifts.

It generates a second current that disrupts the alignment of protons.

The exchange of energy between spin states of protons.

Twitch height decreases, indicating a fade phenomenon.

Fluid-filled structures (e.g., vessels) and soft tissues.

A correction factor involving the cosine of the angle of incidence (θ) is used.

A proportion of the original light has been absorbed by the solution.

80%.

Because oxyhemoglobin absorbs more infrared light and allows more red light to pass through compared to deoxyhemoglobin.

They can be displaced or experience torque forces, leading to serious injury.

A mode that combines real-time Doppler with real-time ultrasound to assess vasculature.

Burns caused by magnetically induced currents in ECG leads.

Fat is bright and water is black.

806 nm.

MRI visualizes soft tissues much better than CT.

Poor perfusion, movement artefact, electrical interference, calloused skin, nail varnish, severe anaemia, cardiac arrhythmias, methaemoglobinaemia, increased venous pulsation, and methylene blue dye.

It potentiates the block by decreasing the rate of suxamethonium breakdown.

It acts as a coupling medium to reduce attenuation of the ultrasound waveform and improve image quality.

Typically used in eye surgery and dermatological procedures.

It produces a substantial increase in ACh release, sufficient to overcome NMBD competition.

About 1 G.

Muscle function returns in reverse order of sensitivity, indicating recovery from NMBDs.

Approximately 85%.

Used as a lasing medium in gas-state lasers for cutting, welding, and engraving.

To house the entire scanner and shield it from external electromagnetic interference.

Items are completely free of all metallic components and pose no hazard in any MR environment.

For vascular line insertion, cardiac output monitoring, echocardiography, transcranial Doppler, pleural aspiration, ascitic drainage, assessment of hepatic portal vein flow, and detection of venous thromboembolism.

Utilizes the Doppler effect to detect and quantify the velocity of flow, with frequency shifts indicating the speed of moving targets like blood.

3 twitches followed by a break of 750 ms, then 3 more twitches.

50 mA.

It prevents oxygen utilization in respiration, causing saturation readings to appear high.

Velocity = (Speed of sound wave × change in frequency) / (2 × emitted frequency).

It stimulates the electrons in the laser medium, raising them from a ground state to an excited state.

In the mid-oesophagus.

The Doppler principle.

To improve the ability to detect fade clinically.

Fat is black and water is bright.

Vascular line insertion, guiding peripheral nerve blockade, and catheter placement within the epidural space.

Suxamethonium binds to the ACH receptor, causing sodium channel opening and membrane depolarization.

It leaves fewer receptors available for ACh to bind to, leading to fade.

Items that pose a hazard in any MR environment.

Weber (Wb) for magnetic flux and Tesla (T) for magnetic flux density.

MR safe ECG electrodes, BP cuffs, and pulse oximeters.

Eyes, facial muscles, neck, extremities, limbs, abdominal muscles, glottis, intercostal muscles.

They emit energy in the form of light or radiation, which can stimulate further electrons and amplify the process.

An electronic processor, two light-emitting diodes (LEDs), and a photodiode.

A block seen after a single dose of suxamethonium, characterized by reduced twitch height and sustained response to tetanic stimulation.

50 Hz (50 every second).

Poor tissue penetration of <200 μm due to absorption by water.

Between 400 and 700 nm (blue-green region of the visible spectrum).

1 T = 10,000 Gauss.

Ambient light and the difference between arterial and venous saturations.

Saline, to prevent ignition from the laser.

Less than 0.25 if tolerated.

A = εlc, where A is absorbance, ε is the molar absorption coefficient, l is the path length, and c is the concentration.

Profound block.

MR Safe, MR Conditional, and MR Unsafe.

Remote location, cold and noisy environment, claustrophobic space, limited space for anaesthetic equipment, and limited access to the patient.

A mode that color codes the velocity and direction of blood flow, superimposing it onto a grey-scale 2D image.

A block that occurs after repeated administration of suxamethonium, leading to receptor desensitization.

Monochromatic, coherent, and collimated.

High-energy intensities can cause fire, explosions, and permanent eye damage.

Unstable patients, young children, patients with learning difficulties, very anxious or claustrophobic patients, and patients with movement disorders.

Around 2 MHz.

By applying an electric field to a piezoelectric crystal in the transducer, causing it to vibrate.

It should not be taken beyond the 50 gauss line unless securely fastened.

To allow fine-tuning and focusing of the image.

Facial nerve, ulnar nerve, and posterior tibial nerve.

Disconnect it.

They are stimulated by ACh release and help increase ACh production through positive feedback mechanisms.

30 times per second.

Electrons are confined to certain energy states and can move between these states by absorbing or emitting energy.

Class 1, Class 2, Class 3a, Class 3b, and Class 4.

A permanent blind spot can develop, or permanent blindness if it hits the optic nerve.

Exhibits fade on tetanic stimulation, post-tetanic facilitation, and TOF ratio <0.3.

Between 1 and 1.5 T, with newer machines generating up to 3–5 T.

Resolution is inversely proportional to depth of penetration; deeper structures have lower resolution.

Designated laser protection supervisor, trained staff, locked doors, closed windows, and warning signs.

A bag-valve-mask circuit.

There will be no discernible weakness until this threshold is reached.

The turning on and off of the gradient magnets.

Stimulated atoms emit photons of equivalent energy, creating a chain reaction that amplifies the light.

Eye damage, skin burns, and airway fire.

Airway fire.

1064 nm (near infrared region).

Used typically for endoscopic surgery.

It is not absorbed by water, allowing good tissue penetration.

Call for help and inform the immediate theatre team.

External energy source, laser medium, chamber, system of mirrors, partially reflective mirror, and windows at Brewster's angle.

Inspect the airway with a rigid bronchoscope.

Laser beam wavelength-specific goggles for both staff and patients.

Double-cuffed, laser-resistant endotracheal tube.

Switch off the laser and flood the operation site with water.