Department of Anaesthesia, Queens Hospital, Burton upon Trent DE13 0RB, UK*Corresponding author
Accepted for publication: July 7, 2000
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Abstract |
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Br J Anaesth 2000; 85: 9257
Keywords: surgery, arthroscopy; complications, air embolism; monitoring
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Introduction |
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Case report |
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Anaesthesia was induced with propofol 200 mg, fentanyl 0.1 mg, and vecuronium bromide 10 mg. The trachea was intubated and ventilation of the lungs was controlled. Anaesthesia was maintained with sevoflurane and nitrous oxide in oxygen. Morphine 10 mg and ondansetron 4 mg was administered. Routine monitoring included end tidal carbon dioxide measurements. The patient was placed in the beach chair position. After a stab incision in the skin, the arthroscope with a pointed trochar was introduced into the left shoulder joint. The joint was seen using the arthroscope and 50 ml of air was injected into the joint by attaching a syringe with air to the inflow portal on the arthroscope. Within 1 min after the injection, a marked drecrease in the end tidal carbon dioxide (ETCO2) from 4.0 to 1.5 kPa was noted. The electrocardiogram showed a 1-mm rise in the ST segment, and the heart rate increased from 56 to 90 beats min1. There were no changes either in the oxygen saturation or in the non-invasive blood pressure. An air embolism was suspected and the patient was placed horizontal and nitrous oxide discontinued. The end tidal carbon dioxide concentration returned to 4.0 kPa after 4 min. The surgical procedure was allowed to continue after ensuring the condition of the patient was stable and the ETCO2 concentration had returned to normal. There was an episode of bradycardia 15 min following the incident during which the heart rate decreased to 38 beats min1. This responded to 0.6 mg of i.v. atropine.
The patient made a full recovery from the anaesthetic at the end of the procedure, without any sequelae. He remained stable for the next 48 h and was discharged home.
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Discussion |
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Although venous air embolism of some degree is detected in all patients undergoing neurosurgical procedures in the sitting position,1 it is very rare in shoulder arthroscopy. Air and other gases have been used to distend the joint in arthroscopy since 1921. Fatal pulmonary air embolism has been reported during arthroscopy of injured knee joints.2 3 It is presumed that air entered the circulation through the exposed venous sinuses in these cases. We are aware of only one case of venous air embolism during a shoulder arthroscopy.4 There are, however, theoretical risks of embolism during this procedure. In the beach chair position, used for shoulder operations, the operative site is higher than the right atrium. In addition, during arthroscopy the pressure inside the joint may be 510 times higher than the venous pressure and if a vein is punctured during insertion of the arthroscope, any agent used to distend the joint may enter the venous system.
Because of the low morbidity and anaesthetic complication rate associated with shoulder arthroscopy, the procedure is performed as a day case in most hospitals. Air is commonly used as the joint distending agent because of the better view obtained, when compared with normal saline.
The possible mechanisms of developing a venous air embolism during arthroscopy are: injection of air into an injured joint, where the air can get into the exposed venous sinuses because the intra-articular pressure during arthroscopy is high and may reach peak values of 300 mm Hg with sudden manipulation of the joint;5 or accidental injection of air into a vein in the joint.
In our case there was no history of trauma, preoperative MRI scans showed no abnormalities in the joint and arthroscopy did not show any disruption in the joint surface. It is presumed that a vein was accidentally punctured during the stab incision or by the introduction of the arthroscope into the joint. The raised intra-articular pressure because of the injected air and the manipulation of the joint resulted in air entering an open vein.
There are several reports in the anaesthetic literature where the use of sophisticated monitors to detect venous air embolism early in operations, with a high risk of development of venous air embolism, has resulted in a significant reduction in morbidity and mortality.
Transoesophageal echocardiography is the most sensitive monitor for early detection of venous air embolism (detects as little as 0.02 ml kg1 of air).6 Others include pulmonary artery catheters, pre-cordial Doppler probe and ETCO2 and nitrogen measurements.
For day case arthroscopies an inexpensive, non-invasive, sensitive and easy-to-use monitor is essential. The pre-cordial Doppler probe meets the above criteria. It is very sensitive, but picks up interference from other sources. Before it becomes a useful tool for early detection of venous air embolism, familiarity with its use is essential. In most district general hospitals, however, capnography remains the main monitor for the early diagnosis of venous air embolism. It has fewer sources of interference than echocardiography and pre-cordial Doppler. It is widely used and is sensitive (sensitivity of 0.4 ml kg min1),7 but is non-specific for air embolism. Above all, awareness of the possibility of air embolism, a high index of suspicion and vigilance are most important in arthroscopy when air or other gases are used to distend the joint. Early detection of venous air embolism will allow for prompt treatment before serious clinical complications develop.
A significant venous air embolism will manifest as bronchospasm, hypoxaemia, hypercapnia, decreased ETCO2, hypotension, cardiac dysrhythmias and cardiovascular collapse, depending on the size of the embolus and the rate of entry of air into the veins.
Management of clinical venous air embolism includes measures to prevent expansion of the embolus and further entry of air into the venous system. The operative site should be lowered below the level of the heart, if possible and flooded with fluids while haemostasis is obtained. Nitrous oxide should be discontinued and oxygen increased to 100%. Blood pressure and central venous pressure should be supported with fluids, vasopressors and inotropes. If a large amount of air is entrained, the left lateral decubitus position may improve right ventricular outflow. Further treatment includes insertion of right atrial catheter and aspiration of air from the right side of the heart. In the event of cardiovascular collapse, cardiovascular resuscitation should be commenced.
Prevention is the key to the management of venous air embolism. Patients at risk should be well hydrated in order to reduce the pressure gradient between the surgical site and the right atrium. Surgical haemostasis is essential at all times. Intravenous air is five times more dangerous than carbon dioxide.8 Therefore, carbon dioxide or normal saline are safer agents for distension of joints during arthroscopy.
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References |
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2 Habegger R, Siebenmann R, Kieser CH. Lethal air embolism during arthroscopy. J Bone Joint Surg (Br) 1989; 71B: 3146[ISI][Medline]
3 Grünwald J, Bauer G, Wruhs O. Tödliche Komplikation bei Arthroskopie im gasförmigen Meduin. Unfallchirurg 1987; 90: 97[ISI][Medline]
4 Faure EAM, Cook RI, Miles D. Air embolism during anesthesia for shoulder arthroscopy. Anesthesiology 1998; 89: 8056
5 Noyes FR, Spievack ES. Extra articular fluid dissection in tissues during arthroscopy: a report of clinical cases and a study of intra-articular and thigh pressures in cadavers. Am J Sports Med 1982; 20: 34651
6 Palmon SC, Moore LE, Lundberg J, Toung T. Venous air embolism: a review. J Clin Anesth 1997; 9: 2517[ISI][Medline]
7 Drummond JC, Prutow RJ, Scheller MS. A comparison of the sensitivity of pulmonary artery pressure, end tidal carbon dioxide, and end tidal nitrogen in the detection of venous air embolism in the dog. Anesth Analg 1984; 64: 68892[Abstract]
8 Graff T, Arbegast NR, Phillips OC, Harris LC, Frazier TM. Gas embolism: a comparative study of air and carbon dioxide as embolic agents in the systemic venous system. Am J Obstet Gynecol 1959; 78: 25965[ISI]