Bronchospasm following supraclavicular brachial plexus block.

Supraclavicular brachial plexus block is commonly performed for upper limb surgeries. In patients with compromised respiratory function or in the elderly it may be preferred over general anaesthesia. Bronchospasm, albeit a rare complication of this procedure, may turn the advantages of regional anaesthesia in these patients into a disadvantage. Bronchospasm following interscalene approach has been previously reported. However, the same following the supraclavicular approach has not yet been reported. A 70-year-old woman presented with cellulitis of the left upper limb. A successful left brachial plexus block was performed uneventfully via the supraclavicular approach for an emergency debridement. She developed bronchospasm in the post-operative care unit (1 hour after the performance of the block) which responded to the standard treatment and rest of her hospital stay was uneventful. Awareness of possibility of this less known complication is necessary, especially in patients of compromised respiratory function to initiate prompt treatment and avoid further complications.

INTRODUCTION

Performing regional anaesthetic techniques like plexus or nerve blocks is an integral part of the armamentarium of anaesthesiologists. Peripheral nerve blocks may be used alone or in conjunction with general anaesthesia.[1] Brachial plexus block by various approaches is the mainstay of anaesthesia and postoperative analgesia for upper limb surgical procedures. Bronchospasm following interscalene approach to brachial plexus block has been reported.[2] Bronchospasm following supraclavicular approach has not yet been reported. We report a patient who developed bronchospasm following supraclavicular brachial plexus block.

CASE REPORT

A 70-year-old woman presented with cellulitis of the left upper limb. There was no other relevant medical or surgical history. The patient denied a previous history of bronchial asthma. On examination, she was febrile, her weight was 45 kg, heart rate was 110/ min and blood pressure in the right upper limb in supine position was 168/96 mmHg. Respiratory and cardiovascular systems were unremarkable. Laboratory investigations showed leucocytosis with neutrophilia and other parameters were within normal limits. ECG showed sinus tachycardia. Oxyhaemoglobin saturation (SpO2) on room air was 96%. She was scheduled to undergo an emergency debridement of the left upper limb.

Regional anaesthesia was planned and left brachial plexus block was performed uneventfully via the supraclavicular approach. Lignocaine (2%) with adrenaline (5 μg/ml) 10 ml and bupivacaine (0.5%) 10 ml was injected after eliciting paresthesia and careful aspiration. The patient developed adequate anaesthesia of the left upper limb within 10 minutes and the heart rate decreased to 80/min. The surgery lasted for 20 minutes and the further intra-operative period was uneventful.

In the post-operative care unit, 30 minutes later, the patient complained of difficulty in breathing and the SpO2 decreased to 88% with O2 4 L/min by face mask. She was using accessory muscles of respiration. The heart rate increased to 120/min. On auscultation, there was reduced air entry bilaterally and rhonchi were heard all over the chest. She was treated with propped-up position, supplemental oxygen, salbutamol nebulization and intravenous hydrocortisone 100 mg. A chest screening done subsequently with a C-arm was normal. ECG showed no fresh changes. At this time, the right upper limb was also examined for any sensory/motor deficit which the patient could not differentiate due to the respiratory distress. A repeat examination of the right upper limb 1 hour later did not reveal any sensory/motor deficit while the left still had adequate anaesthesia. The patient improved with the above treatment and rest of her hospital stay was uneventful.

DISCUSSION

Brachial plexus block is one of the popular methods of anaesthetizing the upper limb. Various complications have been described. Common complications of interscalene approach include hemi-diaphragmatic paresis (100%), intra-arterial local anaesthetic injection, epidural or spinal anaesthesia, cervical sympathetic block (Horner's syndrome) and recurrent laryngeal nerve block.[3] Common complications of supraclavicular approach include hemi-diaphragmatic paresis (50%), pneumothorax, intravascular injection, cervical sympathetic block (20-90%), and recurrent laryngeal nerve anaesthesia (1%).[3] Causes of respiratory distress following brachial plexus block using interscalene approach include unilateral/bilateral phrenic nerve paralysis, pneumothorax or bronchospasm.[2] The patient did not give any history or show any symptoms/signs suggestive of any respiratory compromise before the block. Since there was no contraindication to supraclavicular approach this method, which was a personal preference of the anesthesiologist, was selected Hemi-diaphragmatic paralysis is not as commonly seen after a supraclavicular approach as with the interscalene approach for brachial plexus block. The incidence of phrenic nerve paralysis has been reported to be 50% and paresis 17% following supraclavicular brachial plexus block in one series. All the patients in this series were asymptomatic with normal oxygen saturation on room air.[4] The X-ray screening done postoperatively in our patient showed normal movement of the diaphragm, thus excluding this possibility.

Pneumothorax with a 25G needle, though less likely, could have occurred if a bulla was pricked during the performance of block, considering the patient's age. This differential diagnosis was also ruled out with the chest X-ray. Recurrent laryngeal nerve paralysis as seen with interscalene approach can lead to upper airway obstruction and wheezing. These signs were absent in our patient. Pain, emotional and psychological factors may cause bronchospasm via the efferent pathway of vagus. The operative site was tested and found to be pain free.

The sympathetic nerve supply to the bronchi arises from T1-T4 segments of the sympathetic chain, while the dominant parasympathetic supply is from the vagus nerve. The integrity of normal airway is the result of the balance between the sympathetic (beta) bronchodilators and parasympathetic and sympathetic (alpha) constrictors. Sympathetic blockade associated with spinal and/or epidural anaesthesia produces constriction of the bowel due to unopposed vagal parasympathetic action. Similarly, blocking the sympathetic nerve supply to the bronchi must cause bronchoconstriction due to unopposed vagal parasympathetic action. Local anaesthetics, when injected in the interscalene groove, have been shown to spread to the opposite side if the midline septae are deficient and also spread as far as T4.[5] The same mechanism may be the reason for bronchospasm in our patient. Only 2 cases have been described in the literature,[2] of bronchospasm following brachial plexus block using interscalene approach. To our knowledge, no case has yet been reported of this complication following supraclavicular approach.

Regional anaesthesia is usually preferred for patients with compromised respiratory function undergoing upper limb surgery. The number of elderly patients presenting for anaesthesia and surgery has increased in recent years. Although the type of anaesthesia (general versus regional) has no substantial effect on peri-operative morbidity or mortality in any age group, the elderly benefit from regional anaesthesia because of minimal sedation and excellent analgesia and faster recovery.[5] In our patient, the bronchospasm could have negated the beneficial effects of regional anaesthesia.

Regional anaesthesia does not necessitate instrumentation of the airway. Since elderly patients are more susceptible to hypoxaemic episodes in the post-operative recovery unit, patients who undergo regional anaesthesia may have a lower risk of hypoxaemia.[6] Similarly, the risk of aspiration due to the progressive decrease in the laryngo-pharyngeal sensory discrimination in the elderly can be lowered by the use of regional anaesthesia.[7]

CONCLUSION

Bronchospasm is a less known complication of the supraclavicular approach of the brachial plexus block. Anesthesiologists administering this block should be aware of this possible complication in susceptible patients and diagnose and treat it early and appropriately. Awareness of possibility of this less known complication is necessary, especially in patients of compromised respiratory function to initiate prompt treatment and avoid further complications.