Anaesthetics I Flashcards
Malignant hyperpyrexia syndrome complication
General anaesthetic
Malignant hyperpyrexia is most likely to be secondary to the use of volatile anaesthetic agents.
Reduced variability cardiotocograph.
Intramuscular pethidine
Pethidine, other opiates and some anti-hypertensives (alpha methyldopa and labetalol) reduce CTG variability.
Severe headache
Spinal anaesthetic
In spinal anaesthesia the needle (25G or smaller pencil point - Whitacre or Sprotte - needle which parts dura rather than tears it) goes through the dura while in an epidural it is supposed to inject around the dura but may inadvertently penetrate the dura.
Postdural puncture headache appears to be higher in association with spinal (3%) than epidural (1%).
Aspiration syndrome
General anaesthetic
Sudden maternal hypotension
Epidural
Maternal hypotension is more likely to be due to dural penetration during an epidural anaesthetic as this is the generally intended procedure.
At 3 am you are called to see a man who complains of a painful, swollen calf three days after an abdomino-perineal resection of the rectum. On examination his leg is hot, the calf is swollen and tender but there are good palpable pulses. Active movement is still present.
LMWH
Therapeutic level heparinisation. Clinically this man has a deep vein thrombosis which does occur after surgery in the lithotomy position despite all standard preventative measures. At 3 am you will be very unlikely to get confirmation of your diagnosis and so treatment should be initiated while waiting for an urgent duplex scan. Early treatment is essential to reduce the risk of clot propagation and pulmonary emboli.
Forty-eight hours after a femoro-distal bypass graft for critical limb ischaemia, the nurses note the operated leg is swollen and blistered. The patient has no pain and can move his foot. A palpable pulse is still present in the graft, the leg is warm, sensation is normal and there is no muscle tenderness.
elevation
This limb is swollen due to a reperfusion phenomenon. The limb requires elevation to allow increased venous/lymphatic drainage. If left dependant, swelling will increase and the risk is that suture lines will give way, resulting in graft exposure.
A DVT rarely occurs after vascular surgery. Compartment syndrome - the extreme form of reperfusion injury - usually occurs acutely in the first 24 hours after surgery. There is pain, swelling and usually muscle tenderness. Loss of sensation and function follow if left untreated. The presence of a pulse does not exclude the diagnosis. The treatment is immediate fasciotomy.
Five days post abdominal aortic aneurysm repair a 72-year-old man complains of shortness of breath.
On examination he has decreased breath sounds at both bases and a temperature of 38.2°C.
White cell count 13.6 ×106/L
pO2 10.1 kPa
pCO2 4.5 kPa
pH 7.4
Chest infection
Aortic surgery often leads to diaphragmatic splintage, basal atelectasis, and subsequent infection.
His temperature and WBC (but not PaCO2) would also be consistent with SIRS but he has chest signs so this would be sepsis - SIRS in the presence of infection.
Aggressive physiotherapy, sitting out and early mobilisation are methods of avoiding this, but once established treatment should be with antibiotics, physiotherapy, humidified oxygen, urgent culture of both blood and sputum to ensure that the organism is treated before it can infect the graft.
Seventy-two hours post left hemicolectomy a 69-year-old male smoker complains of chest pain associated with shortness of breath. On examination he has full air entry in his chest. Full blood count, U&E and troponin have been sent. His observations reveal the following. Pulse 110 bpm, regular Blood pressure 100/75 mmHg Respiratory rate 32 Temperature 36.5°C pO2 8.1 kPa pCO2 3.2 kPa pH 7.5
PE
With the information currently available you have to treat as a PE, because he is hypoxic despite his tachypnoea with low pCO2 and is apyrexial.
Treatment with supplemental oxygen and heparin should begin whilst waiting for FBC, U&E and troponin to become available.
A chest x ray and ECG should be performed, and if PE remains the most likely diagnosis a CT pulmonary angiogram/VQ scan should be performed.
A 62-year-old male undergoing an elective right hemicolectomy following the induction of anaesthetic.
The correct answer is Intermittent positive pressure ventilation (IPPV)
This patient will require administration of muscle relaxants to perform the abdominal surgery. The muscle relaxant will produce narcotic-induced apnoea thus the patient will require tracheal intubation and IPPV. The IPPV allows good relaxation with control of the patient’s oxygenation and elimination of carbon dioxide.
A 75-year-old male has under gone an emergency repair of a leaking infrarenal abdominal aortic aneurysm. Following the procedure he was transferred to the intensive care unit ventilated. He has been stable since the procedure and it has therefore been decided to wean him from the ventilator.
The correct answer is Synchronised intermittent mandatory ventilation (SIMV)
The transition from controlled mandatory ventilation to other modes allowing some patient input into ventilation is not an exact science. However, the most common initial step down modes is SIMV. CPAP and PEEP are usually introduced as the patient becomes more conscious.
A 19-year-old male presented to the emergency department unconscious following a collision between his motorcycle and an oncoming car. He required a right thoractomy and laparotomy to control bleeding. The patient was transfused 20 units of blood and developed severe inflammatory response syndrome (SIRS). Despite aggressive ventilation, his PaO2 began to drop.
The correct answer is Extracorporeal membrane oxygenation (ECMO)
Extracorporeal membrane oxygenation/extracorporeal life support which involves veno-venous cardiopulmonary bypass may be considered if the patient is deteriorating despite aggressive ventilation. However, no prospective randomised controlled trials in adults have shown an improved survival.
A 19-year-old man is admitted to the emergency unit following an assault outside a local nightclub. On examination the trachea is deviated to the right, he has low oxygen saturation, is apyrexial and the left chest is hyper-resonant with no breath sounds.
Tension pneumothorax results when the wound in the parietal pleura seals but air continues to escape from the lung, then tension inside the pleura space rises. Eventually the lung on the affected side collapses completely, and as the volume of air in the pleural cavity continues to increase the mediastinum and the trachea are progressively shifted to the other side, resulting in reduced venous return.
Tension pneumothorax is diagnosed clinically by respiratory distress, tracheal deviation to the contralateral side, absence of breath sounds on the ipslateral side +/- distension of the neck veins. Treatment is immediate needle decompression followed by a chest drain.
A 65-year-old man with known chronic obstructive pulmonary disease is noted to have a large left chest radio-opacity, with the mediastinum displaced to the right and the diaphragm flattened on the left on chest radiograph.
Pleural effusion
Pleural effusion. Small effusions may only produce blunting of the costo-phrenic angles. A large effusion can result in lung compression and the radiographic signs described.
Pleural effusions fall into two categories>
- Transudate - malignancy, congestive cardiac failure, cirrhosis
- Exudate - infection, iatrogenic, malignancy.
A 25-year-old motorist sustained a blunt injury to abdomen in a single car collision with a tree. He is shocked and on examination is found to have diminished chest movements on the left, impaired chest wall resonance on the left and abnormal sounds heard on auscultation of the left chest. On the chest radiograph there is an unusual gas filled structure.
Diaphragmatic rupture.
Diaphragmatic ruptures resulting from blunt trauma are usually large and radial. These large tears are usually on the left and allow easy herniation of the abdominal viscera.
Presentation is
- Immediate - the patient presents with shock, pain, haemoperitoneum and/or haemothorax.
- Delayed - effects are due to migration of the abdominal viscera into the thorax.
The diagnosis is confirmed by a coiled NG tube in the left thorax on chest radiograph or by CT. Treatment is urgent laparotomy +/- thoracotomy and repair of hernia.
A 25-year-old motorcyclist was involved in a collision with another vehicle. He complains of back pain, and on examination he is found to be hypotensive and tachycardic, with a marked deformity of the right lower limb. He has normal sensation in both lower limbs.
Hypovolaemic. This young man is most likely to be hypovolaemic from extensive blood loss from a femoral fracture. The back pain may be due to a retroperitoneal haematoma, which may also explain his hypovolaemia.
A 42-year-old woman is found to be tachycardic, normotensive, is warm with well perfused peripheries. Forty eight hours earlier she underwent an insertion of a ureteric stent for symptomatic renal calculi.
Septic
Septic. This woman has developed sepsis and is now becoming shocked. The haemodynamic response to sepsis is a fall in systemic vascular resistance due to the loss of vascular tone and vasodilatation; this results in a reduced cardiac afterload and a reflex increase in cardiac output. Initially blood pressure is maintained but eventually falls due to falling systemic vascular resistance.
A 19-year-old man has sustained a penetrating injury to the anterior chest, on examination he is tachycardic, hypotensive (80/40 mmHg) and has a raised jugular venous pressure (JVP), and muffled heart sounds on auscultation.
Cardiac tamponade
The history suggests cardiac involvement. The signs all point to cardiac tamponade. With blood in the pericardial space the cardiac output will fall, there will be muffled heart sounds and there will be raised JVP due to back pressure which, classically, rises with inspiration (Kussmaul’s sign).
Kussmaul’s sign
Raised JVP due to back pressure which, classically, rises with inspiration
A 65-year-old man complains of chest pain. On examination he is tachycardic, hypotensive and has a raised jugular venous pressure with no narrowing of pulse pressure, and normal heart sounds. He is also noted to have cold peripheries.
Cardiogenic shock
Cardiogenic shock shares many features of hypovolaemic shock, although there is no loss of volume, the failing myocardium results in a fall in cardiac output and a catecholamine induced vasoconstriction resulting in cold peripheries.
Produces prompt but short-lasting analgesia; it is less constipating than morphine, but even in high doses is a less potent analgesic.
Pethidine
It is used for moderate to severe pain; obstetric analgesia; and peri-operative analgesia.
Used for breakthrough pain in patients already receiving opioid therapy for chronic pain. Commonly applied in a patch form. A WHO class 4 analgesic.
Fentanyl
Side-effects include local reactions such as
Rash
Erythema
Itching.
A WHO class 1 analgesic that is converted to a toxic metabolite, N-acetyl-p-benzoquinoneimine, which is inactivated by conjugation to reduced glutathione.
Paracetamol
This is used for mild to moderate pain and whilst side effects are rare, they include rashes and blood disorders.
A WHO class 3 analgesic, which produces analgesia by two mechanisms:
An opioid effect
An enhancement of serotonergic and adrenergic pathways.
Tramadol
Side effects include
Nausea Hypotension Occasionally hypertension Anaphylaxis Hallucinations Confusion.
Has both opioid agonist and antagonist properties, and may precipitate withdrawal symptoms, including pain, in patients dependent on other opioids.
Buprenorphine
This agent is particularly useful for
Moderate to severe pain
Peri-operative analgesia
Opioid dependence.
In patch form it can be used for moderate to severe cancer pain.
A 64-year-old man with dysphagia, dysarthria and right-sided hemiplegia secondary to a massive intracerebral bleed is admitted to the neuro-rehabilitation ward. It appears that he will need nutritional supplementation for a prolonged period.
PEG feeding
Enteral nutrition is the best route for nutritional support since it reduces the incidence of peptic ulceration, decreases liver and renal dysfunctions, decreases bacterial translocation from the gut and reduces the incidence of feeding line and other stoma related complications.
However, it is not possible or appropriate to institute or provide enteral nutrition in certain patients or medical/surgical conditions, as in short bowel syndrome or in oesophagectomy or gastrectomy.
Percutaneous endoscopic gastrostomy (PEG) is the preferred method to feed patients who are unable to eat or swallow food due to a debilitating condition such as stroke or cancer and thus requiring long term nutritional support. It also decompresses the stomach over a prolonged period of time.
A 26-year-old male involved in a high-speed road traffic accident is admitted to the neurosurgical ward with moderate head injury. His GCS was 9 on admission but now he is showing signs of gradual recovery.
Naso-enteric fine-bore feeding
Since this patient is recovering from a head injury, naso-enteric fine bore feeding is an appropriate method of nutritional support.
A 71-year-old woman is undergoing Lewis-Tanner procedure for stage 3 oesophageal carcinoma. She is not due to undergo chemo-radiation post-surgery since this surgical procedure is expected to be curative. She has, however, lost three stone in weight in the last few months, secondary to dysphagia and the malignancy. She needs long term nutritional support.
