Common Adverse Reactions to Medications: Symptoms and Treatments

Malignant Hyperthermia, Neuroleptic Malignant Syndrome, Serotonin Syndrome, Acute Dystonia, and Meningitis are all potential adverse reactions to medications.

Malignant Hyperthermia is a rare condition that can occur after exposure to general anaesthetics or muscle relaxants. Symptoms include a sudden increase in temperature, acidosis, hypercapnia, and widespread skeletal muscle rigidity. Treatment involves dantrolene and supportive care such as cooling and correction of acidosis.

Neuroleptic Malignant Syndrome is a rare idiosyncratic reaction that can occur as a response to taking high-potency anti-psychotic medication. Symptoms include hyperthermia, fluctuating consciousness, rigidity, tachycardia, labile blood pressure, and autonomic dysfunction. Treatment involves discontinuing the medication and supportive management such as fluids and cooling. Dantrolene or bromocriptine may also be used.

Serotonin Syndrome occurs when a patient takes multiple doses, an overdose, or a combination of certain medications. Symptoms include confusion, agitation, hyperreflexia, shivering, sweating, tremor, fever, and ataxia. Treatment involves stopping the drugs and providing supportive care.

Acute Dystonia presents with spasm of various muscle groups and is a side-effect of anti-psychotic medication. It can occur in the first few hours of administration of anti-psychotic medication. It is also seen with the antiemetic metoclopramide where it can cause an oculogyric crisis. It is not usually associated with anaesthesia.

Meningitis is not a complication of anaesthesia or muscle relaxants.

Managing Malignant Hyperpyrexia: An Anaesthetic Emergency

Malignant hyperpyrexia is a life-threatening anaesthetic emergency triggered by inhalational anaesthetics and muscle relaxants in genetically susceptible individuals. It causes a hypermetabolic state, leading to increased CO2 production, oxygen consumption, heat production, metabolic and respiratory acidosis, hyperkalaemia, activation of the sympathetic nervous system, and disseminated intravascular coagulation.

Early signs include a rise in end-tidal CO2, rigid muscles, tachycardia, and tachypnoea. Treatment involves discontinuation of the triggering agent, rapid administration of dantrolene, active cooling, and treatment of hyperkalaemia. Dantrolene inhibits calcium release from the sarcoplasmic reticulum and reverses the hypermetabolic state.

It is important to inform the surgeon and stop the operation. Once the initial reaction is controlled, the patient will require transfer to the ICU and monitoring for 24-48 hours.

In contrast, giving more muscle relaxant or antibiotics is not recommended. Active management and stabilisation of the patient should precede discussion with the ICU. Malignant hyperpyrexia requires prompt recognition and management to prevent serious complications and death.

The Use of Nasopharyngeal Airways in Seizure Management

Nasopharyngeal airways are a valuable tool in managing patients with seizures. During a seizure, jaw rigidity can make it difficult to position an oropharyngeal airway, making a nasopharyngeal airway a better option. These airways are used to secure an open airway in patients with a decreased Glasgow Coma Scale (GCS) score and those who cannot tolerate an oropharyngeal airway due to an intact gag reflex. The correct size of the airway is chosen by sizing the width of the patient’s nostril to the circumference of the tube, and insertion is facilitated by using a water-based lubricant. However, nasopharyngeal airways should not be used in patients with a patent airway or those with basal skull fractures and coagulopathy.

Understanding Pre-Oxygenation and Desaturation Time

Pre-oxygenation is a crucial step in ensuring adequate oxygenation during medical procedures. In a 70-kg man, the functional residual capacity (FRC) is approximately 2.5 liters. If pre-oxygenated adequately, all of the FRC will be 100% oxygen, and oxygen extraction per minute is 250 ml. This means that the patient will have 10 minutes of adequate oxygenation in the absence of ventilation before desaturation occurs.

However, if only 21% (room air) was in the FRC, the patient would only have 2 minutes before they started to desaturate. It is important to note that the oxygen extraction rate is 250 ml per minute in a 70-kg male. A person who has been adequately preoxygenated will not start to desaturate until double this time period, which is 10 minutes.

Therefore, if the patient is oxygenated on room air only, the correct answer for desaturation time would be 2.5 minutes. However, if the patient has been adequately preoxygenated, they will desaturate well before 25 minutes is reached. Understanding pre-oxygenation and desaturation time is crucial in ensuring patient safety during medical procedures.

Common Inducing Anaesthetic Agents and Their Uses

Propofol, etomidate, ketamine, midazolam, and thiopental are all commonly used inducing anaesthetic agents with varying properties and uses.

Propofol is the drug of choice for RSII procedures in normotensive individuals without obvious cardiovascular pathology. It has amnesic, anxiolytic, anticonvulsant, and muscle relaxant properties, but no analgesic effects.

Etomidate provides haemodynamic stability without histamine activity and minimal analgesic effects. It is used in RSI procedures in patients with raised intracranial pressure and cardiovascular conditions, often in combination with fentanyl.

Ketamine is a non-competitive glutamate N-methyl-D-aspartate (NMDA) receptor blocker that produces dissociative anaesthesia. It can be used for induction of anaesthesia in patients with hypotension, status asthmaticus, and shock, but is avoided in hypertensive patients due to relative contraindications.

Midazolam is a benzodiazepine with anticonvulsive, muscle relaxant, and anaesthetic actions. At higher doses or in combination with other opioids, it induces significant cardiovascular and respiratory depression.

Thiopental is administered intravenously as an inducing anaesthetic agent or as a short-acting anaesthetic. It is also used as an anticonvulsant agent and to decrease intracranial pressure in neurosurgical procedures.

Treatment for Mild Hypokalaemia

Mild hypokalaemia can be treated with oral supplementation. If a patient is able to eat, intravenous fluids are unnecessary. It is best to advise the patient to take oral supplements for a few days. Foods such as tomatoes and bananas contain high levels of potassium and could be offered as well. However, it is important to note that the maximum concentration of potassium that can be given via a peripheral line is 40 mmol/L. It is also important to avoid loop diuretics as they can make the patient’s potassium levels even lower. As long as the patient is asymptomatic and able to eat, mild hypokalaemia can be easily treated with oral supplementation.

Anesthesia Grading Score for Patient Risk

The American Society of Anesthesiologists developed a grading score in 1963 to assess patient risk during surgery. The score ranges from one to five and uses Roman numerals to indicate the severity of a patient’s systemic disease. Patients without systemic disease are classified as grade I, while those with mild to moderate systemic disease that does not limit their activities are classified as grade II. Patients with severe systemic disease that causes functional limitations are classified as grade III, and those with severe systemic disease that poses a constant threat to life are classified as grade IV. Additionally, the letter E is added to indicate emergency surgery. Finally, patients who are moribund and unlikely to survive more than 24 hours with or without surgery are classified as grade V. This grading system helps anesthesiologists determine the appropriate level of care and monitoring needed during surgery.

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.

Respiratory Alkalosis: Causes and Effects

Respiratory alkalosis is a condition that occurs when a person hyperventilates, leading to a decrease in the partial pressure of carbon dioxide (PaCO2) in the alveoli. This decrease in PaCO2 causes an increase in the ratio of bicarbonate concentration (HCO3) to PaCO2, which in turn increases the pH of the blood. As a result, the patient may appear to have an alkalosis with a high pH of 7.5, low pCO2, and normal PO2. However, the body tries to compensate for this by lowering the bicarbonate concentration. This condition can be caused by a variety of factors, including anxiety, fever, hypoxia, and pulmonary disease. It can also be a side effect of certain medications or a result of high altitude. Treatment for respiratory alkalosis depends on the underlying cause and may include addressing the underlying condition, breathing techniques, or medication.

Different Flow Rates of Cannulas for Infusions

Cannulas are small tubes inserted into a vein to administer medication or fluids. Different sizes and colors of cannulas are available, each with varying flow rates. The grey 16G cannula has the highest flow rate of 180 ml/min, while the blue 22G cannula has the lowest flow rate of 33 ml/min. The pink 20G cannula is the most commonly used in adults for standard infusions, with a flow rate of 54 ml/min. The green 18G cannula has a flow rate of 80 ml/min, and the orange 14G cannula has the largest size and highest flow rate of 270 ml/min. It is important to choose the appropriate cannula size and flow rate for each patient’s needs.

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.

Intraosseous Access as an Alternative to Intravenous Access in Emergency Situations

In emergency situations where intravenous access cannot be obtained quickly, intraosseous access should be attempted as it is preferred over endotracheal access. According to the Resuscitation Council (UK) guidelines, if intravenous access cannot be established within the first 2 minutes of resuscitation, gaining intraosseous access should be considered. This is particularly important during a cardiac arrest when epinephrine is an essential resuscitation drug. The recommended dose for intraosseous access is the same as intravenous access, which is 1 mg of 1:10,000 adrenaline each 3-5 minutes. Therefore, it is crucial for healthcare professionals to be trained in intraosseous access as it can be a life-saving alternative when intravenous access is not possible.

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.

Cannabinoids and Their Effects

Cannabinoids are compounds found in the resin of cannabis sativa, with 9-tetrahydrocannabinol (9-THC) being the most important active component. However, the oral bioavailability of THC, whether in pure form or as part of marijuana, is low and highly variable, with effects taking anywhere from 0.5 to 3 hours to occur. Smoking marijuana also does not significantly increase bioavailability, with rates rarely exceeding 10-20%.

Interestingly, the analgesic effects of cannabinoids can be blocked by naloxone and other opioid receptor antagonists. Additionally, synthetic cannabinoids have been found to reduce inflammation caused by arachidonic acid by inhibiting eicosanoid production. Overall, the effects and limitations of cannabinoids is important for both medical and recreational use.

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.

Macintosh Laryngoscope: A Tool for Visualizing the Vocal Cords

The Macintosh laryngoscope is a medical instrument designed to aid in the visualization of the vocal cords. Its curved blade is specifically shaped to fit into the oral and oropharyngeal cavity. To use it, the blade is inserted through the right side of the mouth and gradually advanced, pushing the tongue to the left and out of view. The blade has a small bulbous tip that is intended to sit in the vallecula, a small depression between the base of the tongue and the epiglottis.

By lifting the laryngoscope up and forwards, the larynx is elevated, allowing for a clear view of the vocal cords. This tool is commonly used in medical settings, such as during intubation procedures or when examining the airway. Its design allows for a safe and effective way to visualize the vocal cords, aiding in the diagnosis and treatment of various medical conditions.

Measuring Cardiac Output and Pressures with a Pulmonary Artery Catheter

A pulmonary artery catheter can provide direct and derived measurements for assessing cardiac function. Direct measurements include right atrial pressure, right ventricular pressure, pulmonary artery pressure, pulmonary artery wedge pressure, core temperature, and mixed venous saturation. The catheter can also be used to calculate cardiac output using the method of thermodilution. This involves a proximal port with a heater and a distal thermistor that senses changes in temperature.

Pulmonary artery wedge pressure is a direct measurement that can be obtained with the catheter, reflecting left atrial filling. However, it may not always accurately reflect the pressure in the left atrium due to various factors. Right ventricular pressure is another direct measurement that can be obtained.

Central venous saturation is a direct measure in some machines with a built-in saturation measurement probe, while in others, samples can be taken via the distal port and measured using a gas machine. Overall, a pulmonary artery catheter can provide valuable information for monitoring cardiac output and pressures in critically ill patients.

Characteristics of Aortic Stenosis

Aortic stenosis is a condition where the aortic valve becomes narrowed, causing the heart to work harder to pump blood out to the body. Despite this increased workload, the apex beat in aortic stenosis is not displaced but has a heaving character. Additionally, the pulse is typically of small volume and slow rising. The second heart sound may be inaudible or paradoxically split.

It is important to note that the intensity of the murmur is not a reliable indicator of the severity of the disease. As the cardiac output is reduced with more severe disease, the murmur may become less intense. However, the murmur tends to become longer as the disease progresses, due to the longer ejection time needed. These characteristics can help healthcare professionals diagnose and monitor aortic stenosis in patients.

Importance of Correct Patient Identification in Transfusions

Transfusions are a crucial aspect of medical treatment, but incorrect patient identification of samples and blood products can lead to fatal consequences. In fact, it is the most common cause of death following transfusion. Therefore, it is essential to ensure that patient identification is accurate and consistent throughout the process.

If there are any inconsistencies or doubts about the patient’s identity, it is crucial to stop the transfusion immediately and inform the laboratory. This step can prevent serious harm or even death. It is better to err on the side of caution and take the necessary steps to ensure that the patient receives the correct blood product.

In emergency situations where blood is needed immediately, and there is uncertainty about the patient’s identity, group O negative blood may be used. However, this should only be a temporary solution until the patient’s identity is confirmed, and the appropriate blood product can be administered.

In conclusion, patient identification is a critical aspect of transfusions, and any errors or inconsistencies should be addressed immediately to prevent harm to the patient. It is better to take the necessary precautions and ensure that the patient receives the correct blood product, even if it means delaying the transfusion.

Suxamethonium: A Depolarising Muscle Relaxant

Suxamethonium is a type of muscle relaxant that causes muscular fasciculations after being injected intravenously. It quickly induces neuromuscular paralysis, but recovery is spontaneous once it is metabolized by the enzyme pseudo or plasma cholinesterase, which is produced in the liver. However, certain pesticides and drugs, such as ecothiopate iodide, can inhibit cholinesterase activity and prolong the effects of suxamethonium. Additionally, reduced levels of plasma cholinesterase can be caused by liver disease, malnutrition, and pregnancy, while genetically determined abnormal enzymes can also lead to a prolonged action of suxamethonium. It’s important to note that neostigmine and other anticholinesterase drugs do not serve as reversal agents and can actually potentiate the neuromuscular block caused by suxamethonium.

When administering suxamethonium, it’s important to be aware that bradycardia (a slow heart rate) may occur in children after the first dose and in adults after repeated doses. Premedication with atropine should be considered to prevent this. It’s also crucial to note that suxamethonium is a potent trigger of both anaphylaxis and malignant hyperpyrexia, with the incidence of anaphylaxis being highest with rocuronium, atracurium, and suxamethonium.