Inadvertent high spinal anesthesia as sequelae to epidural injection of normal saline.

Here we present a case of high spinal blockade in a patient belonging to ASA Grade I which lead to need for endotracheal intubation. A 35 year old healthy male, weighing 59 kg, of height 165 cms presented with a post traumatic raw area over the left lower limb. A reverse sural graft along with skin grafting (from the thigh) was planned. In OR, the patient was placed in sitting position and the extradural space was identified by 'loss of resistance to air' technique at the L2-L3 intervertebral space. The catheter could not be threaded into the extradural space, hence 5ml of 0.9% saline was injected. However, still the catheter could not be negotiated. Further attempts to identify the extradural space at the L1-L2 and L3-L4 interspace levels were made. During these attempts a total of 18 ml of 0.9% saline was injected into the extradural space. Within 2 minutes blood pressure fell to 90/60 mmHg. Injection mephenteramine (3 mg) was given intravenously and a slight head up tilt was applied. After 2 more minutes the patient started complaining of tingling in his hands and difficulty in breathing. Oxygen 100% was administered via a face mask attached to the anesthesia circle system. In view of onset of respiratory failure, general anesthesia was induced. Thiopentone (200 mg) and Suxamethonium (75 mg) were given intravenously, the patient's trachea was intubated and his lungs ventilated with 40% oxygen, 60% nitrous oxide and 0.2-0.4% Isoflurane, without additional neuromuscular blockade. The arterial saturation promptly returned to 97% and, immediately after intubation, the heart rate was found to be 103 beats/min and the arterial BP 162/102 mmHg. At the end of surgery, spontaneous ventilation returned and the patient was allowed to breathe 100% oxygen via the tracheal tube until he awoke, when his trachea was extubated.

INTRODUCTION

Combined spinal-epidural (CSE) technique involves the purposeful subarachnoid blockade and epidural catheter placement during the same procedure.

The administration of drugs into the epidural space via the catheter can supplement and prolong the duration of analgesia during surgery and also into the postoperative phase.[1] Time and again it has proved its mettle as a valuable addition to the armamentarium of the anesthesiologist.

However, a subarachnoid block given after passing an epidural catheter can have unusual complications at times. One such unanticipated and unwarranted adversity is the cephalad spread of the block owing to volume effect as described by Park et al.[2] Despite years of use, controversy still surrounds the appropriate steps to ensure the safe consummation of CSE anesthesia.

Here, we present a case of high spinal blockade in an American Society of Anesthesiologists Grade-1 patient.

CASE REPORT

A 35-year-old healthy male, weighing 59 kg, of height 165 cm presented with a posttraumatic raw area over the left lower limb. A reverse sural graft along with skin grafting (from the thigh) was planned. All his routine investigations were within normal limits.

Preloading was done by 1 L of ringer lactate. Subsequently, the patient was placed in sitting a position, and the extradural space was identified by “loss of resistance to air” technique at the L2-L3 intervertebral space. The catheter could not be threaded into the extradural space; hence 5 ml of 0.9% saline was injected. However, the catheter could not be negotiated still.

Extradural spaces at L1-L2 and L3-L4 were identified, but the catheter could not be threaded. During these attempts, a total of 18 ml of 0.9% saline was injected into the extradural space in trying to open the space. Finally, an 18-gauge Portex epidural catheter was inserted 3 cm into the L2-L3 extradural space. Then, a 25-gauge needle was introduced via the L3-L4 interspace, and 3 ml of 0.5% Bupivacaine (heavy) was injected into the cerebrospinal fluid (CSF). Immediately the patient was placed in the supine position.

Within 2 min the block extended bilaterally to the T3 level and the blood pressure (BP) fell to 90/60 mmHg. Injection mephentermine (3 mg) was given intravenously and a slight head up tilt was applied in an attempt to reduce further upward extension of the advancing block.

After 2 more min, the patient started complaining of tingling in his hands and difficulty in breathing, and the oxygen saturation (SpO2) decreased to 90%. Oxygen (100%) was administered via a face mask attached to the anesthesia circle system. Despite this, the SpO2 further decreased to 75%, the patient was unable to breathe, showed evidence of weakness in both arms, and was also unable to phonate. Meanwhile, the BP decreased to 70/40 mmHg. Injection mephentermine (6 mg) was given intravenously, and manual ventilation of the lungs via face mask was instituted.

In view of the onset of respiratory failure, general anesthesia was induced. Following preoxygenation, thiopentone (200 mg) and suxamethonium (75 mg) were given intravenously, the patient's trachea was intubated and his lungs ventilated with 40% oxygen, 60% nitrous oxide and 0.2–0.4% isoflurane, without additional neuromuscular blockade. The arterial saturation promptly returned to 97% and immediately after intubation; the heart rate was found to be 103 bpm and the BP 162/102 mmHg. No further muscle relaxant was required for 30 min after the induction of general anesthesia. Then, when diaphragmatic movements started returning, vecuronium (1 mg) was given.

At the end of surgery, 0.5 mg of glycopyrrolate and 2.5 mg of neostigmine were given to reverse neuromuscular blockade. Spontaneous ventilation returned, and the patient was allowed to breathe 100% oxygen via the tracheal tube until he awoke, when his trachea was extubated. By this time the neuraxial block had regressed and he had good muscle power in his upper limbs as well as in his lower limbs. The following day, the patient was comfortable with no further sequelae.

DISCUSSION

Classically, total central neurologic block (total spinal anesthesia) occurs within 3 min of injecting an analgesic drug and is associated with apnea, fixed dilated pupils, loss of consciousness and hypotension.[3] In our patient, apnea and ascending muscle weakness occurred soon after the placement of the block.

Of further importance in using CSE technique is the observation that there is a decreased need for epidural, spinal, or total local anesthetic administration to achieve the required level of sensory block.[4]

In contrast to conventional combined spinal and epidural anesthesia, in the present case report, spinal, local anesthetic was administered after prior epidural administration of 20 ml of 0.9% saline, resulting in a high block. High spinal anesthesia after prior epidural anesthesia has been reported by Richardson et al. suggesting that there may be a common mechanism for this phenomenon.[5]

Epidural injection of normal saline (10 ml) in an attempt of priming the space has been described as a method to reduce catheter related complications by Gadalla et al.[6] since we encountered problems with catheter negotiation, we planned on injection of normal saline through the epidural needle at levels where epidural space was identified.

It has also been postulated that prior epidural administration of local anesthetic may cause collapse of the subarachnoid space below the termination of the cord;[7] hence, a given volume of subarachnoid anesthetic may spread more extensively.

Similar postulation, that the rapidity of extension of spinal anesthesia is caused by increased volume within the extradural space, causing a decrease in CSF volume in the caudal subarachnoid space and cephalad shift of local anesthetic within the CSF, was given by Blumgart et al.[8]

Furthermore, reduction in CSF volume following epidural saline injection has been confirmed by Higuchi et al. by magnetic resonance imaging studies.[9] This further confirms the findings that we encountered in our case.

However, epidural volume extension has been used as a rescue technique in CSE block. This proves beneficial in raising the sensory level of the block.[10]

Therefore, epidural normal saline has been used beneficially when applied as a method. The rationale for its use has to be clearly weighed, and a risk-benefit ratio must always be kept in mind.

CONCLUSION

Our study reiterates the momentousness of vigilance and expeditious decision-making abilities of an anesthesiologist. Even though the case presented has been a case of regional anesthesia, it clearly underlines the significance of circumspection during each inquest. This case report aims to exhort practitioners that the use of epidural saline injection as a technique cannot be recommended and may have grave consequences for the patient.