POST-OPERATIVE Chapter 15 and 16

Dr. Vasanthi Vidyasagaran*

Department of Anaesthesiology, Kauvery Hospital, Chennai, Tamilnadu, India

*Correspondence: Vasanthi.vidyasagaran@gmail.com

Dr. Vasanthy Vidyasagaran Muralidharan

POST-OPERATIVE Chapter 15

Nerve Blocks in Day Care

Case 1

A 45-year-old woman was posted for diagnostic arthroscopy of her right knee in view of her arthritic symptoms. She had no significant past medical or surgical history. It was thus planned as a day care procedure under general anaesthesia. All her investigations were within normal limits.

She was premedicated with injection Glycopyrrolate 0.2 mg and fentanyl 100 µg, induced with Propofol 120 mg and intubated with Atracurium 30 mg. The surgery was uneventful and lasted half an hour. At the end of the procedure, femoral nerve block with 8 ml of 2% Lignocaine with Adrenaline and 8 ml 0.5% Bupivacaine was given for post-operative analgesia. She was reversed and extubated, and shifted to the recovery room.She was instructed not to move without help and support.

Two hours later there was a sudden cry from the postoperative recovery room. On enquiry and further examination, it was found that the patient had fallen down and sustained injury in her left leg in an attempt to walk. Despite the warning regarding the consequences of the femoral nerve block, patient did not pay heed to it. Muscle weakness (anticipated from the block) precipitated the injury. Investigations revealed she sustained fracture of left tibia. She had to undergo an unplanned emergency open reduction and internal fixation of tibia. She recovered well from the second surgery, but had to be hospitalised for a further period of five days.

Case 2

An obese lady weighing 150 kg, with severe rheumatoid arthritis had undergone total knee replacement. Surgery was uneventful under combined epi spinal anaesthesia. she had recovered from the spinal effect. Fentanyl 25 mics along with .125% bupivacaine 10 ml was administered in the epidural at 6 pm. Later, at around 12 midnight the patient had walked to the rest room herself with help of a relative even without informing the floor nurse! It was quite unimaginable, that such a patient, would venture walking up to the rest room herself in the immediate post-operative period. She had a massive fall, her skin broke open, and she had a popliteal artery injury which required major emergency vascular surgery. She nearly lost her limb. This was not a day care procedure, but mentioned here since the weakness caused

by the epidural could have been the precipitating factor and this patient should not have even attempted to walk. An indwelling urinary catheter might have helped to prevent such a major post- operative incident, though catheterisation by itself may have its own complications in such patients.

Discussion

The number, diversity and complexity of surgeries performed as outpatient procedures are on the rise. We have moved miles away from the original criteria set for admission and discharge for day-care procedures; from only doing ASA 1 patients, requiring simple procedures, and not needing any investigations, to performing moderate surgeries on ASA category 2 and above patients.

The discharge criteria depend on recovery from anaesthesia in real terms: Alertness, Ambulation, Analgesia and Alimentation (4 As).

Pain management is now receiving great attention in day-care anaesthesia. Newer drugs and techniques are being applied to achieve this goal. Peripheral nerve blocks are one of them. Advantages include good analgesia with minimum side effects, less risk of hypotension and reduced need for systemic opioids and hence risk of respiratory depression. The side effects of having an effective regional block mean no sensation and inevitably some degree of motor block, depending on the concentration and volume of drug used and the site of block. This often cannot be avoided, although ultrasound guided specific sensory block may be very helpful and is advisable.

In these circumstances, considering the pros and cons of nerve blocks, communication and education of the patient and relatives is essential. Learning point here is that the patient education is of core importance to make this service effective and complete. Or else complications may happen and medicolegal implications have to be faced.

Alternatives such as combination of multimodal analgesia, intraarticular injections may help and prove effective. Selective low dose spinal anaesthesia, unilateral block, use of Ropivacaine, ultrasound guided low volume nerve blocks are in vogue. Right choices have to be made based on the patients’ capacity to understand as well as what is appropriate for that patient’s condition and surgery. Follow up of the patient may be important to know the success rate of the blocks and incidence of complications.

References

  • N Rawal Anaesthesia for day-case surgery British Journal of Anaesthesia 87 (1): 73-87 (2001)
  • SS Harsoor Changing concepts in anaesthesia for day care surgery Indian J 2010 Nov-Dec; 54(6): 485–488.
  • Chilvers CR, Goodwin A, Vaghadia H, Mitchell GW. Selective spinal anaesthesia for outpatient laparoscopy: Pharmacoeconomic comparison vs general anaesthesia. Can J 2001; 48:279–83.
  • Stierer TL, Wright C, George A, Thompson RE, Wu CL, Collop N. Risk assessment of obstructive sleep apnoea in a population of patients undergoing ambulatory J Clin Sleep Med. 2010; 6:467–72.
  • Jin FL, Chung Postoperative pain- a challenge for anesthesiologist in ambulatory surgery. Can J Anaesth. 1998;45:293–6

 

POST-OPERATIVE Chapter 16

Not Realizing the ‘Gravity’ of Myasthenia Gravis

A 12-year-old boy, weighing 30 kg, was posted for emergency surgery for fracture of both bones in the right forearm. He gave no past medical history except taking some tablets from a physician in his own locality, ‘for strength’.He had not taken it for the last two or three days. This was presumed to be multivitamins. The parents were not carrying the prescription or the tablets to verify the drug. Systemic examination revealed no abnormality and all basic investigations were within limits. It was decided to proceed with general anesthesia for this child.

Anaesthesia was induced with 100 mg Propofol and Fentanyl 50 microgram. Airway was secured with using a 6.5 size cuffed ETT after relaxation with Atracurium 25 mg. and was maintained with Oxygen/Nitrous oxide and Sevoflurane 1%. Surgery lasted about 2 hours. One dose of additional 5 mgs Atracurium was given. At the end of surgery, there was no attempt at breathing.

Saturation was 100% and patient was hemodynamically stable. Neuromuscular monitoring was then applied to check for return of activity. But there was no movement of the muscle on stimulating the ulnar nerve.

At this juncture, the causes of delayed recovery from anaesthesia were ruled out one by one. Haemogram, blood sugar and urea, serum electrolytes, and arterial blood gas were normal. Pupils were equal and reacting. Temperature was normal. History was not suggestive of head injury. Role of opiates was ruled out as pupil size was normal, and the total Fentanyl used was only 50 micrograms one hour ago.

Differential diagnosis at this stage was some form of neuromuscular disease and further investigations were necessary to reach diagnosis. The child was given supportive ventilation. He showed no signs of recovery until two hours after surgery when he attempted to breathe, and TOF showed return of muscle contraction. Reversal with 1.5 mg Neostigmine and 0.4 mg Glycopyrrolate was given. He recovered well, regaining full consciousness and muscle power.

Postoperatively, the parents were asked to bring the medications. They turned out to be Pyridostigmin and steroids! Parents had taken the child to a doctor near their hometown with persistent weakness, fatigue, and inability to play games at school. The doctor had done some tests and then given them this

medicine, and the child had been keeping well since then. However, they had no idea about the diagnosis and how important and relevant it was to any surgical procedure.

The patient was referred to the hospital neurologist. Electromyography testing was done, and the diagnosis was confirmed as Myasthenia Gravis. The family had to be educated on the illness and medication. They needed to know how vital this drug was for their child’s normal muscular functioning, particularly in the peri-operative period. A letter indicating the diagnosis and medication was provided to them for future reference.

Myasthenia gravis is a disease of great significance to the anesthesiologist because it affects the neuromuscular junction. Many patients with this condition are treated by surgical thymectomy.

Implications under anaesthesia

  • Patients are very sensitive to non-depolarizing NMBAs and are resistant to Succinylcholine. Hence doses must be titrated carefully. If reversal of NMBAs is required, reversal agents should be titrated to effect, guided by the use of an objective twitch monitor.
  • Peri-operative care plan has to be well defined
  • Close watch in high dependency unit will be needed

‘Red flags’ in the history to raise concerns are;

  • Bulbar symptoms (e.g. dysphagia, dysarthria, nasal speech, or low-intensity speech) which may predispose to aspiration
  • History of myasthenic crisis and need for endotracheal intubation
  • Respiratory muscle weakness, shortness of breath, and dyspnoea
  • Associated diseases, including other autoimmune diseases (e.g. thyroiditis, rheumatoid arthritis, systemic lupus erythematosus)

Four risk factors, score ≥ 10 points suggest need for postoperative ventilation

  • Duration of disease longer than 6 years (12 points)
  • COPD independent of respiratory dysfunction (10 points)
  • Pyridostigmine greater than 750 mg/day (8 points)
  • Preoperative vital capacity less than 2.9l (4 points)

Medications that the patient may be on include: Prednisolone, Azathioprine, Cyclosporine, Pyridostigmine.

Medications that may exacerbate Myasthenia Gravis include:

  • Antibiotics like Macrolides, Gentamicin
  • Antiepileptic like Phenytoin
  • Antiarrhythmic agents like beta-blockers, Quinidine, calcium channel blockers, Lignocaine
  • Paradoxically steroids may exacerbate symptoms. They may be indicated (as an immunosuppressive agent) when there is a crisis.

References

  • Mark Abel et al. Anaesthetic implications of myasthenia gravis The Mountsinai Journal of Medicine January/March 2002
  • Jamal BT, Herb K. Perioperative management of patients with myasthenia gravis: prevention, recognition, and treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107:612.
  • Blobner M, Mann R. Anesthesia in patients with myasthenia gravis. Anaesthesist. 2001; 50:484– 93.
  • Viby-Mogensen J. Postoperative residual curarization and evidence-based anaesthesia. Br J Anaesth. 2000;84:301–3

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