Questions & explanations
1. What steps are taken to reduce the risk of aspiration during general anesthesia for cesarean?
Before surgery, the mother is given a medicine to reduce stomach acid and increase stomach emptying, such as a non-particulate antacid (like sodium citrate). She may also receive metoclopramide to speed up stomach emptying and a drug like ranitidine to lower acid. The mother is positioned with a slight head-up tilt or left uterine displacement. A rapid sequence induction is used: the mother is given a fast-acting anesthetic and a muscle relaxant, then the breathing tube is placed quickly while pressure is applied to the cricoid cartilage (Sellick's maneuver) to block the esophagus. This technique minimizes the chance of stomach contents entering the lungs.
2. What is perioperative myocardial injury (MINS)?
Perioperative myocardial injury (MINS) is damage to the heart muscle that happens during or within 30 days after noncardiac surgery. It is caused by a mismatch between oxygen supply and demand or by blood clots in the heart arteries. MINS is diagnosed by a rise in cardiac troponin levels, a protein released when heart cells are injured. It often occurs without chest pain, so doctors must check troponin in high-risk patients. Risk factors include older age, heart disease, diabetes, and emergency surgery. Management includes oxygen, beta-blockers, aspirin, and treating the underlying cause. Early detection and treatment improve outcomes.
3. Compare the causes of MINS: supply-demand mismatch versus coronary thrombosis.
MINS can be caused by two main mechanisms. Supply-demand mismatch happens when the heart needs more oxygen than it gets, for example during low blood pressure, fast heart rate, or anemia. This is more common in patients with narrowed arteries. Coronary thrombosis is a blood clot that blocks a heart artery, causing a heart attack. This is less common but more dangerous. Both cause troponin rise, but thrombosis often requires stronger blood thinners. Doctors tell them apart by ECG changes and sometimes by angiography. Treatment differs: supply-demand mismatch needs fixing the trigger, while thrombosis needs clot-busting drugs or stents.
4. How do you manage a patient with MINS after hip surgery?
First, give oxygen if oxygen levels are low. Start beta-blockers like metoprolol to slow the heart and reduce oxygen demand. Give aspirin to prevent further clots. Check hemoglobin; if low, transfuse blood to improve oxygen delivery. If the patient has chest pain or ECG changes, consider urgent heart catheterization to open blocked arteries. Control pain and keep blood pressure stable. Monitor troponin daily until it falls. After discharge, start a statin and refer to a cardiologist. Avoid stopping antiplatelet drugs unless bleeding risk is high. The goal is to protect the heart and prevent another injury.
5. Compare drug clearance in a full-term newborn versus a preterm newborn.
A full-term newborn (born after 37 weeks) has more mature liver and kidneys than a preterm newborn (born before 37 weeks). For example, the liver enzyme that breaks down caffeine is present in full-term babies but very low in preterm babies. So preterm babies clear caffeine much more slowly, and doctors give lower doses. Similarly, kidney function is even lower in preterm babies because their kidneys are still developing. Preterm babies are also smaller, so drug doses are adjusted for weight and gestational age. Overall, preterm babies need even more careful drug dosing than full-term babies.
6. What should be done if the spinal block is too high (high spinal) and the mother has trouble breathing?
A high spinal occurs when the numbing medicine spreads too far up the spine, affecting nerves that control breathing. The mother may feel unable to breathe, have a weak voice, or lose consciousness. Immediate action includes giving oxygen by mask and helping the mother breathe with a bag-valve-mask. The head of the bed is raised slightly, and IV fluids are given. If breathing stops, the mother is intubated (a tube placed in the windpipe) and given mechanical ventilation until the block wears off. Blood pressure is supported with medicines. The baby is delivered quickly if not already out.
7. What are the risks of using ketamine sedation in a child with high blood pressure or a fast heart rate?
Ketamine can raise blood pressure and heart rate because it stimulates the sympathetic nervous system (the 'fight or flight' system). In a child who already has high blood pressure or a fast heart rate, this can be dangerous. It might cause a very high blood pressure or irregular heartbeats. Therefore, doctors avoid ketamine in children with uncontrolled high blood pressure, heart disease, or conditions like thyroid storm. They may choose another sedative like propofol or etomidate instead. If ketamine must be used, they monitor blood pressure closely and have medicines ready to lower it.
8. How does video-assisted awake intubation differ from fiberoptic?
Video-assisted awake intubation uses a video laryngoscope, which has a camera on a curved blade. The doctor inserts the blade into the mouth to lift the tongue and see the vocal cords on a screen. Then, a tube is passed under direct vision. This method does not require a flexible scope and can be faster. However, it may cause more gagging because the blade touches the back of the throat. Fiberoptic intubation uses a thin, flexible scope that can navigate around obstacles and is often better for patients with limited mouth opening. Both are effective; choice depends on the situation.
9. How can you tell apart malignant hyperthermia from sepsis in a child under anesthesia?
Both can cause high fever and fast heart rate, but MH usually starts suddenly after giving certain drugs, while sepsis develops over hours. In MH, the muscles become stiff (rigid), especially the jaw, and the child may have dark urine from muscle breakdown. Sepsis often has low blood pressure, poor blood flow, and signs of infection like high white blood cell count. Also, MH causes a very high end-tidal CO2 (carbon dioxide in exhaled breath) because muscles produce too much CO2. A blood gas test shows high potassium and acid in MH, while sepsis may show low oxygen and high lactate.
10. Give an example of a complication of awake intubation and how to prevent it.
A common complication is coughing or gagging during the procedure, which can cause the patient to move and make intubation harder. To prevent this, adequate topicalization with lidocaine is essential. Also, gentle technique and reassurance help keep the patient calm. Another complication is bleeding from the nose if using the nasal route, which can be prevented by using a vasoconstrictor spray like oxymetazoline. If the patient becomes too sedated, they may stop breathing, so careful drug dosing and monitoring are crucial. Always have suction ready to clear secretions or blood.
11. What is the risk of post-dural puncture headache with CSE compared to epidural alone?
The risk of post-dural puncture headache (PDPH) is slightly higher with CSE than with epidural alone. PDPH happens when the needle punctures the dura (the tough covering of the spinal cord) and spinal fluid leaks out, causing a headache that worsens when sitting up. In CSE, a deliberate dural puncture is made for the spinal injection, but the needle is very small (pencil-point), which reduces the leak. Epidural alone uses a larger needle and does not intentionally puncture the dura, so the risk is lower. However, the overall risk of PDPH with CSE is still low (about 1-2%).
12. What are the indications for awake intubation?
Awake intubation is indicated when the doctor predicts that placing a tube after sedation will be difficult or dangerous. This includes patients with a known difficult airway from previous surgeries, facial burns, large neck masses, or severe arthritis of the neck. It is also used in patients with unstable neck injuries where moving the neck could cause spinal cord damage. Other indications include patients with severe airway swelling from infection or allergy. In these cases, awake intubation allows the patient to maintain their own airway until the tube is safely placed.