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Isolated peripheral radial nerve injury with the use of the favaloro retractor
Isolated Peripheral Radial Nerve Injury With the Use of the Favaloro Retractor Sarojini Rao, MD, Brian Chu, MD, and Ketan Shevde, MD
RA.CHIAL PLEXUS injuries have been well documented in patients undergoing coronary artery bypass graft (CABG) surgery with median sternotomy? '2 Most often the ulnar nerve is injured by compression of the first rib. With increasing use of internalmammary artery grafts (IMA), neurological injuries resulting from the various sternal retractors may become more common. For example, the Favaloro retractor (American V Mueller Co, Ft Lauderdale, FL) has been implicated in the disappearance of ipsilaterai radial artery tracings 36 and could I cause nerve injuries. A case is reported in which the patient not only had vascular compression during IMA dissection, but also developed wrist drop postoperatively due to compression injury of the radial nerve at the level of the mid-upper arm. :
B
CASE REPORT A 58-year-old white male (body weight, 98 kg) with a history of unstable angina underwent a quadruple CABG procedure with the use of bilateral IMA and saphenous vein grafting. He had a history of an old inferior wall myocardial infarction and thrombectomy of the left lower leg in 1981. Medications included propranolol, 40 mg four times a day, isosorbide dinitrate, 2.5 mg orally every day, and sublingual nitroglycerin, ~]~mgrain as required. The patient was premedicated with morphine, 8 mg, scopolamine, 0.4 mg intramuscularly (IM), and diazepam, 10 mg orally, one hour prior to surgery. In the operating room, monitoring included a fivelead electrocardiogram, a 20-gauge left radial artery cannula for arterial pressure, and a pulmonary artery catheter placed through the right internal jugular vein. A 14-gauge intravenous (IV) catheter was inserted in the right arm for IV fluid infusion. A blood pressure cuff was not used on either arm. Prior to the induction of anesthesia, both arms were placed at the patient's sides in the supine position. Anesthesia was induced with sufentanil and oxygen, and muscle relaxation was produced with pancuronium, followed by an atraumatic endotracheal intubation. Anesthesia and relaxation were maintained with sufentanil, oxygen, and pancuronium. Following median sternotomy, a Favaloro self-retaining sternal retractor was used to elevate the sternum for surgical exposure of the left IMA. During dissection of the IMA, the left radial artery pressure tracing was noted to be damped. The arterial cannula and the wrist were examined for malpositioning, the tubing was carefully examined for kinks and the presence of air bubbles, and the transducer system was checked for malfunction; these were all found to be normal. There was free flow of blood from the arterial line upon withdrawal with a syringe. The surgeon repositioned the retractor and decreased the tension on the sternum by
loosening the retractor screws, with resultant return of the arterial waveform. Fifteen minutes later, an identical brief episode occurred; this also resolved by further reduction of tension on the retractor by the surgeon. The remainder of the surgical procedure was uneventful. After the patient was extubated nine hours postoperatively, he complained of numbness of the left thumb and inability to move his left wrist. Neurological evaluation revealed a left wrist drop with minimal sensory loss, but he had no difficulty in moving his left shoulder. Nerve conduction studies (electromyogram) performed on the second postoperative day revealed complete left radial nerve impairment up to the level of the mid-upper arm, with intact triceps activity indicating a peripheral radial nerve injury. Six weeks after surgery, there was considerable improvement in the patient's neurological status; however, nerve conduction studies were not repeated at this time.
DISCUSSION
The Favaloro retractor is a sturdy, metallic device consisting of two vertical bars, upon which is suspended a horizontal rod. The vertical bars are attached to the side of the operating table adjacent to the arm (Fig 1). Tremendous retraction force can be generated by screwing on two retractors from the free edge of the sternum to the horizontal piece. Disappearance of the radial artery pressure tracing and brachial plexus injury have been previously described with this device. 6 The most common peripheral neurological complication following median sternotomy is a brachiai plexus injury. This usually involves the medial, lateral, or posterior cord, or a combination of the three. Occasionally, C8 and TI nerve roots may also be involved. Ulnar nerve injury has most often been reported. ~'2 The most common etiology is traction or compression of the brachial plexus at the thoracic outlet due to sternal retraction and posterior displacement of the first rib. The distal radial nerve injury seen in the
Front the Department o f Anesthesia, Maimonides Medical Center, Brooklyn, NY. Address reprint requests to Ketan Shevde, MD, Maimonides Medical Center, 4802 Tenth Ave, Brooklyn, N Y !1219. 9 1987 by Grune & Stratton, Inc.
Journal of Cardiothoracic Anesthesia, Vol t, No 4 (August), 1987: pp 325-327
0888-6296/8.7/0104-0012503.00/0 325
326
RAO, CHU, AND SHEVDE
of the brachial plexus in the thorax. This complication has not been previously reported. The most likely mechanism for this injury is compression of the radial nerve between the metallic vertical arm of the retractor and the humerus, where the nerve winds around the lateral' aspect of the bone (Fig I). The degree of compression and ischemia is influenced by the patient's weight, size of the upper body, position of the arm, and the force with which retraction is applied. Early recognition of vascular compression and prompt repositioning of the retractor was sufficient to relieve arterial obstruction, but not to prevent radial nerve damage. It is recommended that the placement of the Favaloro retractor be Closely monitored by the anesthesiologist and the surgeon. In a large patient whose arm protrudes beyond the width of the operating room table (especially if there is i !0ss of the arterial pressure waveform), manual ..... : retraction can be utilized instead of a mechanical retractor capable of producing tremendous sustained compression. Another possible preventive measure is to keep the ipsilateral arm extended on an arm board with the table Favaloro retracFig 1. Favaloro retractor showing direct compression (arrow) of upper arm in a large volunteer. tor placed between the arm and the body to prevent arterial and nerve compression (Fig 2). An alternative is to use the sternal Favaloro reported case probably occurred as a result of retractor (if avaiiable) instead of the table Favadirect pressure from one of the vertical limbs of Ioro retractor (described in this case) for dissecthe Favaloro retractor. The electromyogram tion of the IMA, since the former requires no demonstrated that the injury was between the vertical bars. axilla and the elbow, and ruled out direct injury
Fig 2. With the use of an arm board, the arm can be extended and the retractor placed safely b e t w e e n the arm'and the body during I M A dissection.
FAVALORO RETRACTOR
327
REFERENCES
1. Vander Salm T J, Cereda JM, Cutler BS: Brachial plexus injury following median sternotomy. J Thorac Cardiovase Surg 80:447-451, 1980 2. Vander Salm T J, Cutler BS, Okike ON: Brachial plexus injury following median sternotomy. J Thorac Cardiovase Surg 83:914-917, 1982 3. Kinzer JB, Lichtenthal PR, Wade LD: Loss of radial artery pressure trace during internal mammary artery dissection for CABG surgery. Anesth Analg 64:1134-1136, 1985
4. Nicolson SC, Jobes DR: Arterial pressure monitoring during internal mammary harvesting. Anesth Analg 65:819-827, 1986 5. Graham JG, Pye IF, McQueen INF: Brachial plexus injury after median sternotomy. J Neuro Neurosurg 44:621-625, 1981 6. Hanson MR, Breuer C, Furlan A J, et al: Mechanism and frequency of brachial plexus injury in open heart surgery. Ann Thoracic Surg 36:675-679, 1983
RA.CHIAL PLEXUS injuries have been well documented in patients undergoing coronary artery bypass graft (CABG) surgery with median sternotomy? '2 Most often the ulnar nerve is injured by compression of the first rib. With increasing use of internalmammary artery grafts (IMA), neurological injuries resulting from the various sternal retractors may become more common. For example, the Favaloro retractor (American V Mueller Co, Ft Lauderdale, FL) has been implicated in the disappearance of ipsilaterai radial artery tracings 36 and could I cause nerve injuries. A case is reported in which the patient not only had vascular compression during IMA dissection, but also developed wrist drop postoperatively due to compression injury of the radial nerve at the level of the mid-upper arm. :
B
CASE REPORT A 58-year-old white male (body weight, 98 kg) with a history of unstable angina underwent a quadruple CABG procedure with the use of bilateral IMA and saphenous vein grafting. He had a history of an old inferior wall myocardial infarction and thrombectomy of the left lower leg in 1981. Medications included propranolol, 40 mg four times a day, isosorbide dinitrate, 2.5 mg orally every day, and sublingual nitroglycerin, ~]~mgrain as required. The patient was premedicated with morphine, 8 mg, scopolamine, 0.4 mg intramuscularly (IM), and diazepam, 10 mg orally, one hour prior to surgery. In the operating room, monitoring included a fivelead electrocardiogram, a 20-gauge left radial artery cannula for arterial pressure, and a pulmonary artery catheter placed through the right internal jugular vein. A 14-gauge intravenous (IV) catheter was inserted in the right arm for IV fluid infusion. A blood pressure cuff was not used on either arm. Prior to the induction of anesthesia, both arms were placed at the patient's sides in the supine position. Anesthesia was induced with sufentanil and oxygen, and muscle relaxation was produced with pancuronium, followed by an atraumatic endotracheal intubation. Anesthesia and relaxation were maintained with sufentanil, oxygen, and pancuronium. Following median sternotomy, a Favaloro self-retaining sternal retractor was used to elevate the sternum for surgical exposure of the left IMA. During dissection of the IMA, the left radial artery pressure tracing was noted to be damped. The arterial cannula and the wrist were examined for malpositioning, the tubing was carefully examined for kinks and the presence of air bubbles, and the transducer system was checked for malfunction; these were all found to be normal. There was free flow of blood from the arterial line upon withdrawal with a syringe. The surgeon repositioned the retractor and decreased the tension on the sternum by
loosening the retractor screws, with resultant return of the arterial waveform. Fifteen minutes later, an identical brief episode occurred; this also resolved by further reduction of tension on the retractor by the surgeon. The remainder of the surgical procedure was uneventful. After the patient was extubated nine hours postoperatively, he complained of numbness of the left thumb and inability to move his left wrist. Neurological evaluation revealed a left wrist drop with minimal sensory loss, but he had no difficulty in moving his left shoulder. Nerve conduction studies (electromyogram) performed on the second postoperative day revealed complete left radial nerve impairment up to the level of the mid-upper arm, with intact triceps activity indicating a peripheral radial nerve injury. Six weeks after surgery, there was considerable improvement in the patient's neurological status; however, nerve conduction studies were not repeated at this time.
DISCUSSION
The Favaloro retractor is a sturdy, metallic device consisting of two vertical bars, upon which is suspended a horizontal rod. The vertical bars are attached to the side of the operating table adjacent to the arm (Fig 1). Tremendous retraction force can be generated by screwing on two retractors from the free edge of the sternum to the horizontal piece. Disappearance of the radial artery pressure tracing and brachial plexus injury have been previously described with this device. 6 The most common peripheral neurological complication following median sternotomy is a brachiai plexus injury. This usually involves the medial, lateral, or posterior cord, or a combination of the three. Occasionally, C8 and TI nerve roots may also be involved. Ulnar nerve injury has most often been reported. ~'2 The most common etiology is traction or compression of the brachial plexus at the thoracic outlet due to sternal retraction and posterior displacement of the first rib. The distal radial nerve injury seen in the
Front the Department o f Anesthesia, Maimonides Medical Center, Brooklyn, NY. Address reprint requests to Ketan Shevde, MD, Maimonides Medical Center, 4802 Tenth Ave, Brooklyn, N Y !1219. 9 1987 by Grune & Stratton, Inc.
Journal of Cardiothoracic Anesthesia, Vol t, No 4 (August), 1987: pp 325-327
0888-6296/8.7/0104-0012503.00/0 325
326
RAO, CHU, AND SHEVDE
of the brachial plexus in the thorax. This complication has not been previously reported. The most likely mechanism for this injury is compression of the radial nerve between the metallic vertical arm of the retractor and the humerus, where the nerve winds around the lateral' aspect of the bone (Fig I). The degree of compression and ischemia is influenced by the patient's weight, size of the upper body, position of the arm, and the force with which retraction is applied. Early recognition of vascular compression and prompt repositioning of the retractor was sufficient to relieve arterial obstruction, but not to prevent radial nerve damage. It is recommended that the placement of the Favaloro retractor be Closely monitored by the anesthesiologist and the surgeon. In a large patient whose arm protrudes beyond the width of the operating room table (especially if there is i !0ss of the arterial pressure waveform), manual ..... : retraction can be utilized instead of a mechanical retractor capable of producing tremendous sustained compression. Another possible preventive measure is to keep the ipsilateral arm extended on an arm board with the table Favaloro retracFig 1. Favaloro retractor showing direct compression (arrow) of upper arm in a large volunteer. tor placed between the arm and the body to prevent arterial and nerve compression (Fig 2). An alternative is to use the sternal Favaloro reported case probably occurred as a result of retractor (if avaiiable) instead of the table Favadirect pressure from one of the vertical limbs of Ioro retractor (described in this case) for dissecthe Favaloro retractor. The electromyogram tion of the IMA, since the former requires no demonstrated that the injury was between the vertical bars. axilla and the elbow, and ruled out direct injury
Fig 2. With the use of an arm board, the arm can be extended and the retractor placed safely b e t w e e n the arm'and the body during I M A dissection.
FAVALORO RETRACTOR
327
REFERENCES
1. Vander Salm T J, Cereda JM, Cutler BS: Brachial plexus injury following median sternotomy. J Thorac Cardiovase Surg 80:447-451, 1980 2. Vander Salm T J, Cutler BS, Okike ON: Brachial plexus injury following median sternotomy. J Thorac Cardiovase Surg 83:914-917, 1982 3. Kinzer JB, Lichtenthal PR, Wade LD: Loss of radial artery pressure trace during internal mammary artery dissection for CABG surgery. Anesth Analg 64:1134-1136, 1985
4. Nicolson SC, Jobes DR: Arterial pressure monitoring during internal mammary harvesting. Anesth Analg 65:819-827, 1986 5. Graham JG, Pye IF, McQueen INF: Brachial plexus injury after median sternotomy. J Neuro Neurosurg 44:621-625, 1981 6. Hanson MR, Breuer C, Furlan A J, et al: Mechanism and frequency of brachial plexus injury in open heart surgery. Ann Thoracic Surg 36:675-679, 1983