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Venous Air Embolism During Transurethral Resection of the Prostate

Frasco, Peter E. MD*; Caswell, Renee E. MD*; Novicki, Donald MD

doi: 10.1213/01.ANE.0000136847.41264.60
Technology, Computing, and Simulation: General Articles: Case Report
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Venous air embolism during transurethral surgery is a rare event. There have been case reports in the anesthesia and urology literature of fatal air embolism during transurethral prostate resection and transurethral incision of the bladder neck. We present a case of nonfatal venous air embolism during transurethral prostate resection in which incorrect assembly of the bladder irrigation-resectoscope-drain system led to a rapid entrainment of air into the open venous channels of the prostate bed.

IMPLICATIONS: The incorrect assembly of a bladder irrigation system caused air to be pumped from an open drain through the resectoscope into the bladder, which led to a near fatal cardiac arrest caused by venous air embolism. Anesthesiologists and urologists should be aware of this potential complication.

Departments of *Anesthesiology and †Urology, Mayo Clinic Scottsdale, Arizona

Accepted for publication June 11, 2004.

Address correspondence and reprint requests to Peter E. Frasco, MD, Department of Anesthesiology, Mayo Clinic Hospital, 5777 East Mayo Blvd., Phoenix, AZ 85054. Address e-mail to frasco.peter@mayo.edu.

Venous air embolism (VAE) during transurethral surgery is a rare event. There have been case reports in the anesthesia and urology literature of fatal air embolism during transurethral prostate resection (TURP) (1,2) and transurethral incision of the bladder neck (3). We present a case of nonfatal VAE during TURP in which incorrect assembly of the bladder irrigation-resectoscope-drain system led to a rapid entrainment of air into the open venous channels of the prostate bed.

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Case Report

An 80-yr-old man was scheduled for TURP for symptomatic urinary outflow obstruction secondary to benign prostatic hypertrophy. The patient's medical history was significant for well-controlled hypertension treated with triamterene/hydrochlorothiazide and amlodipine and a remote history of nonsustained supraventricular tachycardia. His preoperative electrocardiogram was notable of the presence of right bundle branch block. The remainders of the preoperative testing and laboratory evaluation were negative.

Spinal anesthesia was initiated with 1.3 mL of hyperbaric bupivacaine 0.75%. Fifteen minutes after the injection of the local anesthetic, the surgical procedure began. The patient complained of pain with insertion of the resectoscope. The sensory level was judged to be inadequate, and general anesthesia was induced with propofol. A laryngeal mask airway (LMA; Laryngal Mask Co, Henley-on-Thames, England) was inserted, and the procedure began. Anesthesia was maintained with sevoflurane and nitrous oxide in 40% oxygen. The procedure was performed in the low lithotomy position on a cystoscopy table. Sixty-two grams of benign prostatic material were resected using a continuous flow resectoscope over a 60-min resection time. The patient was hemodynamically stable throughout the procedure but did require ephedrine (10 mg IV) to treat low blood pressure (82/54 mm Hg) after the induction of general anesthesia. At the end of the resection, the resectoscope and irrigation system were disassembled. A three-way Foley catheter was inserted and continuous bladder irrigation instituted, but the irrigation fluid remained grossly bloody. The catheter was removed, and the resectoscope was reinserted to attempt additional hemostasis. A large amount of air was present in the bladder after the initial filling of the bladder from the irrigation system. The equipment was checked, and it was noted that the inflow and outflow lines to the irrigation pump had been reversed (Fig. 1A) during reassembly of the system. The tubing was reconnected in the proper fashion (Fig. 1B), and the prostatic fossa was fulgurated. The patient's heart rate abruptly decreased to 29 bpm from 55 bpm. The arterial saturation decreased to 73%. Nitrous oxide was discontinued, and the patient was manually ventilated with 100% oxygen. Atropine 1 mg was given IV. Asystole ensued within 30 s. Advanced cardiac life support algorithm was initiated. Epinephrine 1 mg was given IV. The LMA was removed, and the trachea was intubated. During the transition from LMA to endotracheal tube, the patient made a gasping effort. A loud mill wheel murmur was present over the precordium. The initial resuscitation was successful with restoration of cardiac rhythm and arterial blood pressure. VAE was suspected. The patient was placed in a slight head down position, however the cystoscopy table did not allow for lateral tilt. A multiplane transesophageal echocardiogram probe was inserted. Initial four-chamber image was notable for complete opacification of the right atrium and right ventricle (Fig. 2A) and paradoxical motion of the intraventricular septum. There was no evidence of right to left shunt across the atrial septum. Initial Doppler examination of the pulmonary artery was notable for an absence of flow. Epinephrine infusion at 0.05 μg · kg−1 · min−1 was started. A right radial arterial line was inserted. An attempt was made to access the right internal jugular vein to attempt aspiration of air, but this was unsuccessful. A left-sided external jugular 16-gauge line was placed for access. The arterial saturation improved to 90%. Arterial blood pressure improved with titration of the epinephrine infusion.

Figure 1

Figure 1

Figure 2

Figure 2

The air in the right atrium and ventricle cleared within 20 min (Fig. 2B). The patient's clinical condition improved during this period. The left external jugular line was removed. A left internal jugular 7F triple-lumen catheter was placed for access. The patient was transferred to the intensive care unit (ICU) in stable condition.

Initial assessment in the ICU included arterial blood gas analysis and chest radiograph. The patient's clinical picture was consistent with adult respiratory distress syndrome (ARDS). The patient required urgent cardioversion for atrial fibrillation with a rapid ventricular response within 4 h of arrival in the ICU. Subsequent electrocardiogram and troponin and creatine phosphokinase-MB levels were consistent with subendocardial myocardial infarction. Transthoracic echocardiogram was notable for the absence of regional wall motion abnormalities and preserved left ventricular systolic function. The patient's respiratory status required mechanical ventilation with positive end-expiratory pressure (no more than 10 cm H2O) but improved over a 72-h interval. He was tracheally extubated on postoperative Day 3. Neurologic examination was normal.

The patient was discharged from the hospital on postoperative Day 7 without functional impairment. He was voiding without difficulty 1 yr after discharge and has had no long-term sequelae as result of the air embolism.

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Discussion

Passive VAE has been described in various clinical scenarios in the operating room (OR). VAE can occur whenever the heart is below the level of the surgical field. Air can be passively drawn into an open, noncollapsible vein by the negative intrathoracic venous pressure (4). Use of the low lithotomy position with the head positioned below the level of the prostate, bladder, or bladder neck is sufficient to create the required gradient to increase the risk of passive VAE.

In addition to passive movement of air into an open venous system, active VAE can occur when air is forced into an open venous channel (2,5). Use of the Ellik evacuator to rinse the bladder or irrigation of a three-way Foley catheter with an air/fluid filled syringe (1,2) can introduce air under pressure into the open venous sinuses of the prostate. There are no published reports of VAE in transurethral surgery associated with the use of an irrigation pump system. In the present case, an unknown quantity of air was pumped into the bladder over a period of 15–30 seconds. This occurred because the waste and patient lines were reversed during reassembly of the resectoscope circuit and drainage equipment once bleeding from the prostatic fossa was suspected.

The manufacturer labels the pump assembly with (a) arrows indicating the correct direction of flow and (b) warnings to “Follow flow path” and “Do not pump into patient.” The irrigation system is designed to drain fluid from the resectoscope via a continuous roller pump system. This pump system is calibrated to drain 750–800 mL/min at the setting used during transurethral surgery. The waste line is connected from the resectoscope to either a central drain in the floor of the OR or to a large container. If the lines are connected incorrectly, as occurred in the present case, air can be pumped from the drain or container through the resectoscope and into the patient. We have since modified the irrigation pump so that the inflow and waste portions of the pump are fitted with connections of different sizes. These size differences prevent improper connection of the inflow and outflow tubing. In addition, we have placed photo enlargements of the proper assembly in the appropriate locations in the ORs dedicated to urology. The use of color-coded inflow and outflow pump connections and tubing is an alternative solution.

The factors that influence morbidity and mortality of VAE include rate of entrainment, volume of air entrained, position of patient during the event, and cardiac status of the patient (6). The lethal volume of IV air in humans is estimated to be between 200 and 300 mL (7). There is no way to quantify the amount of air that our patient received. However, as calibrated, the irrigation system could have rapidly delivered as much as 200–400 mL during the 15- to 30-second episode. Air was present on the right side of the heart for approximately 20 minutes. The air was probably reabsorbed at the alveolar-capillary interface (8). We did not detect air in the left heart, suggesting that the patient had neither a patent foramen ovale nor transpulmonary passage of air.

The patient developed a clinical picture consistent with ARDS. This is a known complication of VAE (9). The shock state caused by acute right ventricular outflow tract obstruction and obstruction of the pulmonary arterioles by the air microemboli may cause activation of polymorphonuclear leukocytes, liberation of chemical mediators, and capillary injury, leading to ARDS (9).

In conclusion, we present a case of nonfatal VAE during TURP under combined spinal-general anesthesia. The source of the air was an improperly assembled irrigation system. This incorrect assembly caused air to be pumped from an open drain through the resectoscope into the bladder. Anesthesiologists and urologists should be aware of this potential complication.

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References

1. Hofsess DW. Fatal air embolism during transurethral resection. J Urol 1984;131:355.
2. Vacanti CA, Lodhia KL. Fatal massive air embolism during transurethral resection of the prostate. Anesthesiology 1991;74:186–7.
3. Tsou MY, Teng YH, Chow LH, et al. Fatal gas embolism during transurethral incision of the bladder neck under spinal anesthesia. Anesth Analg 2003;97:1833–4.
4. Faberowski LW, Black S, Mickle JP. Incidence of venous air embolism during craniectomy for craniosynostosis repair. Anesthesiology 2000;92:20–3.
5. Nowitz A, ArtRu AA. Air embolism during radical cystectomy with ileal conduit urinary diversion. Anesthesiology 2002;96:506–8.
6. Durant TM, Long J, Oppenheimer MJ. Pulmonary (venous) air embolism. Am Heart J 1947;33:269–81.
7. Toung TJK, Rossberg MI, Hutchins GM. Volume of air in a lethal venous air embolism. Anesthesiology 2001;94:360–1.
8. Presson RG, Kirk KR, Haselby KA, et al. Fate of air emboli in the pulmonary circulation. J Appl Physiol 1989;67:1898–902.
9. Verstappen FT, Bernards JA, Kreuzer F. Effects of pulmonary gas embolism on circulation and respiration in the dog. IV. Origin of arterial hypoxemia during pulmonary gas embolism. Pflugers Arch 1977;370:71–5.
© 2004 International Anesthesia Research Society