Types of Laryngoscopes

Laryngoscopes are medical instruments used to visualize the larynx and facilitate intubation. There are several types of laryngoscopes, each with its own unique features. The Miller, Oxford, and Wisconsin laryngoscopes have straight blades, while the Macintosh and McCoy laryngoscopes have curved blades. The McCoy laryngoscope is typically used for difficult intubations, as its blade tip is hinged and can be operated by a lever mechanism on the handle. Overall, the choice of laryngoscope depends on the individual patient and the specific needs of the intubation procedure.

Management of Anaphylaxis: Medications and Dosages

Anaphylaxis is a severe and potentially life-threatening allergic reaction that requires immediate treatment. The first-line management for anaphylaxis is the administration of adrenaline, also known as epinephrine. The dosage of adrenaline varies depending on the age of the patient. For adults, 0.5 ml of 1 : 1000 adrenaline should be given intramuscularly (im), and the dose can be repeated after 5 minutes if there is no response. In children, the dosage ranges from 150 to 500 micrograms depending on age.

Intravenous (iv) administration of adrenaline is not recommended at a concentration of 1 : 1000. However, iv adrenaline can be administered at a concentration of 1 : 10 000 by an anaesthetist, titrated according to effect. An adrenaline infusion may be necessary for cardiovascular support of the patient.

Chlorpheniramine and hydrocortisone are also part of the treatment for anaphylaxis, but adrenaline takes priority. The dosages of these drugs vary depending on the age of the patient and can be given either im or through a slow iv injection.

It is important to note that anaphylaxis is a medical emergency, and prompt treatment with the appropriate medications is crucial for a positive outcome.

Post-Operative Foot Drop Caused by Prolonged Pressure on Common Peroneal Nerve

Prolonged pressure on the common peroneal nerve during anaesthesia is a well-known cause of post-operative foot drop. It is important to ensure that patients are adequately padded on the fibula head when positioning them under general or regional anaesthesia for extended periods of time. While a central neurological cause is unlikely to cause such well-defined peripheral nerve lesions, it is essential to take precautions to prevent nerve damage during surgery.

Treatment for post-operative foot drop is typically conservative, and the transient neuropraxia can often pass. However, in some cases, this may result in permanent injury. It is crucial to monitor patients closely after surgery and provide appropriate care to prevent further complications. By taking preventative measures and providing proper post-operative care, healthcare professionals can help reduce the risk of post-operative foot drop and other nerve injuries.

Prognostic Indicators for Hypoxic Brain Injury Patients

Hypoxic brain injury patients require ancillary tests to aid in determining their prognosis. Bilaterally absent somatosensory evoked responses (SSEPs) at 24–72 hours and complete generalised suppression of electroencephalographic (EEG) waves on day three are reliable indicators of poor prognosis. Absent pupillary or corneal reflexes at three days after cardiac arrest, along with the absence of motor response, is also a better prognostic marker. However, in the absence of either one of these factors, the prognosis should be evaluated using results from ancillary tests (SSEP/EEG). Extensor motor response on day three, despite the absence of motor response, is a reliable indicator for poor prognosis. Myoclonic status epilepticus (MSE) – bilateral and synchronous myoclonus of the face, limbs and axial skeleton – has been studied as a reliable marker for poor prognosis in these patients, even in the presence of brainstem and motor responses. However, it should not be considered in isolation as a prognostic indicator. It is important to note that the reliability of these indicators may be affected by factors such as noise interferences, hypothermia, and drugs given during resuscitation.

Comparison of Different Anesthetic Agents

Propofol is a short-acting anesthetic agent with an elimination half-life of four hours. It is commonly used for day case procedures and sedation in intensive care units. On the other hand, etomidate is no longer preferred due to its side effects such as postoperative nausea and vomiting, venous thrombosis, and interference with glucocorticoid production. Ketamine, a phencyclidine derivative, can cause hallucinations and nightmares. Methohexitone may lead to involuntary muscular movement and epileptiform activity on an EEG. Lastly, thiopentone has the longest elimination half-life of 12 hours, which can cause a prolonged hangover effect.

In summary, different anesthetic agents have their own advantages and disadvantages. It is important to choose the appropriate agent based on the patient’s condition and the type of procedure being performed.

Understanding Heat Loss During Surgery: The Role of Radiation, Convection, Conduction, Evaporation, and Respiration

During surgery, the body can lose heat through various mechanisms. Radiation, which accounts for 40% of heat loss, depends on factors such as body temperature and the environment. To combat this, patients are covered with warming methods like the Bair Hugger™. Convection, or air movement, contributes to 30% of heat loss, while conduction (5%) occurs through contact with the operating table and surrounding air. Evaporation (15%) is higher if the abdomen is open, and humidity is kept at 50% in the theatre to reduce it. Finally, respiration accounts for 10% of heat loss. Understanding these mechanisms can help healthcare professionals better manage patient temperature during surgery.

Diagnosis of Subarachnoid Haemorrhage

Subarachnoid haemorrhage can be diagnosed with a high degree of accuracy through an urgent CT scan, which can confirm the condition in 95% of patients. In most cases, a lumbar puncture is not necessary unless the patient’s medical history suggests the need for one and the CT scan results are normal. If a bloody tap is suspected, the number of red blood cells should decrease with each successive sample. If an LP is performed six hours after the onset of symptoms, the supernatant fluid should be examined for xanthochromia after centrifugation.

Entonox: A Mixture of Nitrous Oxide and Oxygen

Entonox is a gas mixture of 50% nitrous oxide and 50% oxygen that is stored in cylinders. The cylinders have a French blue body with blue and white quarters at the top. It is important to note that if the gas mixture cools below its pseudocritical temperature of −6°C, the nitrous oxide and oxygen may separate out through a process called lamination. This can result in a potentially dangerous and hypoxic gas being administered.

Despite being a flammable mixture, Entonox is not considered explosive. It is effective in providing short-term analgesia and is safe for both infants and mothers. The onset of action occurs approximately 30 seconds after inhalation, and the duration of action after analgesia is approximately one minute.

It is important to distinguish nitrous oxide (N2O) from nitric oxide (NO) as they are not the same. Overall, Entonox is a useful gas mixture for providing short-term pain relief, but it must be stored and administered properly to avoid any potential risks.

Oculogyric Crisis

Oculogyric crisis is a type of acute dystonic reaction that is commonly associated with the use of neuroleptics and anti-emetic medications like metoclopramide. Unfortunately, the clinical spectrum of this condition is not well understood, which often leads to misdiagnosis as a psychogenic disorder. Symptoms of oculogyric crisis can occur suddenly or over several hours and may include restlessness, agitation, malaise, and a fixed stare. The most characteristic symptom is the upward deviation of the eyes, which may be sustained or accompanied by other eye movements like convergence or lateral deviation. Other associated symptoms may include neck flexion, mouth opening, tongue protrusion, and ocular pain. Fortunately, the symptoms of oculogyric crisis can be rapidly resolved with the use of medications like procyclidine.

Managing a ‘Can’t Intubate’ Scenario in a Patient with Neck of Femur Fracture

In a ‘can’t intubate’ scenario with a patient who has a neck of femur fracture, the priority is delivering oxygen. If attempts at intubation have been difficult and the patient is desaturating, the Difficult Airway Society recommends attempting ventilation with a laryngeal mask airway (LMA) as a temporary measure. If this fails and the patient continues to desaturate, an emergency cricothyrotomy is advised for urgent oxygen delivery. Using a videolaryngoscope to secure a definitive airway is not recommended if oxygenation is a priority. Similarly, attempting a fibreoptic intubation or using a long blade for further attempts at intubation can cause damage and swelling in the airway, leading to laryngospasm. Waking the patient up is also not advisable in this emergency situation, as neck of femur fractures have a high mortality rate if left untreated.