Critical Incidents During Anesthesia

Critical Incidents During Anesthesia

Cyanosis

Cyanosis it is the appearance of a bluish color to the skin or mucus membrane that is usually due to a lack of oxygen in the blood. Central cyanosis reflects systemic hypoxia, can usually be detected at an arterial oxygen saturation of about 80-85%. Note that Absence of cyanosis does not necessarily mean normal arterial oxygen levels. anesthesia machine.

Treatment depends upon the diagnosis but the first act must be to cut off all volatile and intravenous anesthetics and administer 100% oxygen, auscultate the chest for bilateral air entry, suction the tube, if the saturation is not corrected inform the surgeon the condition and stop operation and see for other possible causes.

Hypertension During Anesthesia

Hypertension under anesthesia may be defined as systolic arterial blood pressure > 20% above the preoperative value. This usually happens because the depth of anesthesia is inappropriate to the intensity of the stimulus. Typical examples would be tracheal intubation at induction of anesthesia and the subsequent and too rapid onset of surgery. Hypercarbia during the surgery is another possibility. Intraoperative hypertension not responding to an increase in anesthetic depth with opioids and with a volatile agent can be treated with a variety of parenteral anti hypertensive agents. Readily reversible causes such as inadequate anesthetic depth, hypoxemia, or hypercapnia should always be excluded before initiating antihypertensive therapy. Intraoperative hypertension is usually controlled with an intravenous dose of 5-20 mg of hydralazine. The onset of action is within 15 min, and the antihypertensive effect usually lasts 2-4 h. Labetalol 5-20 mg or Propranolol 1-3 mg is an alternative antihypertensive.

Hypotension During Anesthesia

Hypotension under anesthesia may be defined as a systolic arterial blood pressure < 20% pre-operative value. It is important to remember that blood pressure alone does not correlate with tissue perfusion, and that perfusion is more likely to be compromised where hypotension is associated with reduced cardiac output and accompanied by vasoconstriction. The most common causes of unwanted hypotension, apart from surgical consequences of which hemorrhage is the most frequent, and central neural blockade are bradycardia, hypovolemia and drug overdose (which may be relative or absolute). Severe intraoperative hypotension is an anesthetic emergency. Swift recognition and treatment is vital to ensure adequate organ blood flow; particularly to the brain, heart, kidneys and the fetus in pregnancy. If hypotension is not corrected the consequence include brain eschemia, myocardial infarction, acute renal failure and in obstetric patients, fetal compromise.

Immediate management of severe hypotension

• Call for help
• Inform the surgical team and discuss possible causes
• Administer 100% oxygen and ensure effective manual ventilation of the lungs (if under general anesthetic)
• Reduce volatile agent / TIVA (whilst avoiding awareness)
• Make a rapid assessment of airway, breathing and circulation (ABC) and institute specific treatment
• Administer an intravenous fluid bolus e.g. 500cc crystalloid fast, and assess the response, if the couse is heamorrhage give fluids according the calculated los and consider blood transfusion accordingly. Elevation of legs also improves venous return. If still no response consider administration of ephedrine (5mg IV and titrate up to 50 mg upon the response) or Adrenaline 5-15mic. Gram/min infusion

Bronchospasm

Bronchospasm during surgery may be detected clinically by listening to breathe sounds during expiration. Capnography will show a rising end tidal CO2 and a typical trace showing a prolonged and flattened expiratory curve.

The smoker, the asthmatic, the patient with chronic obstructive airways disease and inadequate anesthetized patients, recent upper respiratory tract infection are susceptible to bronchospasm. Pre-operative physiotherapy and appropriate drug therapy should be arranged. Unexpected bronchospasm during anesthesia in a patient with normal lungs is a matter for concern and may reflect aspiration, abutment of a tracheal tube on the carina, or intra-operative drug hypersensitivity (e.g. hypersensitivity to an antibiotic). Bronchospasm may also be the first physical sign of impending pulmonary edema.

Treatment of intra-operative bronchospasm should be instituted as follows.

• Stop the surgery and increase the inspired concentration of volatile agent.
• Check the position of a tracheal tube. Give sympathomimetic agents (ephedrine, aminophylline, salbutamol inhaler.
• Consider Dexamethasone
• Aspirate the tracheo-bronchial tree.
• Stop the administration of any antibiotic; and with drug hypersensitivity in mind
• Check and manage other causes that increase air way pressure, such as kinked endotracheal tubes, aspiration, pulmonary edema, and pneumothorax.

Failure to Breathe

Failure to breathe at the end of the procedure is commonly due to delayed recovery from the use of muscle relaxants. At the end of the surgical procedure the aim is to have the patient pain free, breathing spontaneously, stable cardiovascular system with reactive pupils, opening the eyes and mouth to command, and remembering nothing of the surgery. Delayed recovery from the use or abuse of muscle relaxants is less common than it used to be although there may be occasional problems secondary to the use of suxamethenium.

Causes of Failure to Reverse: Suxamethonium is metabolized by plasma cholinesterase (pseudocholinesterase). A relative lack of pseudocholinesterase (some patients in the third trimester of pregnancy; severe malnutrition and genetic abnormality) will result in a prolongation of action of the drug. Management is explained in emergence session

Cardiac Arrhythmias

An arrhythmia (also called dysrhythmia) is an irregular or abnormal heartbeat. Cardiac arrhythmias are relatively common during general anesthesia.

Bradycardia

A slow heart rhythm with a rate below 60 beats per minute. An adult patient who arrives in the anesthetic room with a heart rate of less than 60 beats per minute may, after induction and especially when an opioid is used, drop their heart rate to less than 40 beats per minute. The systemic arterial blood pressure may be adversely affected. In such patients, it may be wise to increase the heart rate before induction to 70 beats per minute or more by the judicious use of vagolytic agents (e.g., atropine 0.5 -1 mg/kg). If the heart rate does not respond to atropine it is wise to consult the physician specialist. Causes of intraoperative bradycardia include anesthetic drugs (halothane, opioids) vagal stimulation (traction on mesentery or extra-ocular muscles)

Treatment of perioperative bradycardia

• Consult the surgeon about the problem.
• Decrease or shut off anesthetics (if the bradycardia is severe).
• Ensure that your airway is clear and you are administering 100% oxygen. Ask the surgeon to stop the surgery for a few minutes.
• Administer atropine, up to1 mg IV. If this does not increase the heart rate to an acceptable level, then repeat every 3-5 minutes for a total of 3 mg or 0.04 mg/kg.
• If atropine is not successful consider an epinephrine drip. Mix 1 mg of epinephrine in 500 ml of normal saline (2 mcg of epinephrine per l ml). Use an infusion pump (if available) to infuse the epinephrine mixture at 1-5 ml per minute. If you do not have access to an infusion pump, you can titrate epinephrine, but this should be done with extreme care because a lethal dose of epinephrine can easily be administered.
• If bradycardia persists, consider stopping the surgical procedure and waking the patient.
• Consult with the surgeon about further management of the patient

Adult heart rates above 100/min in the anesthetic room usually mean inadequate pre-operative medication, and during surgery (unless secondary to hemorrhage) inadequate anesthesia, Other causes of hypovolemia such as vomiting, diarrhea, diuretic therapy, long NPO time, bowel preparations etc . Give drugs with analgesic effect such as Pethidine, Fentanyl or if there is no contraindication small analgesic dose of ketamine. If it is not responding to analgesia and is beyond 150.min inform the surgeon and treat with beta blockers.

Cardiac arrest is the cessation of blood circulation as a result of absent or ineffective cardiac mechanical activity. In general the clinical signs of cardiac arrest include apnea or agonal gasps, no palpable pulse and unresponsiveness. There are several causes of cardiac arrest in the operating room. The most common cause of cardiac arrest is hypoxia and hypercarbia, due insufficient ventilation and oxygenation. Other causes include: preexisting cardiac disease, acute myocardial infarction, pulmonary embolus, and severe hypovolemia. It is important to remember that virtually all general anesthetics cause some degree of cardiac depression and associated peripheral vasodilatation. It is important to monitor the patient's electrocardiograph (ECG) for heart rate and rhythm changes. Oxygen saturation and blood pressure should also be monitored. It only takes three to four minutes of hypoxia to cause severe brain damage. If an ECG is available it should be used for all anesthetic cases. If a cardiac defibrillator is available it should be used to treat ventricular tachycardia and ventricular fibrillation. Vigilant monitoring of the patient for early recognition of cardiac arrest is critical. This will be discussed in module 9. Treatment of cardiac arrest without an ECG is extremely difficult, since the rhythm cannot be identified. Prompt recognition is essential for timely and successful treatment. Delays in treatment will result in a decreased likelihood of successful resuscitation. Upon recognition of an absent pulse, you will need to follow these steps: