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Venous air embolism during radical perineal prostatectomy
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Venous Air Embolism during Radical Perineal Prostatectomy Michael P. Jolliffe, MD, * Michael A. Lyew, MB, F’RCA,t Ines H. Berger, MD,: Thomas Grimakli, ha>$ Department of Anesthesiology York at Buffalo, Buffalo, NY.
An abrupt decrease in end-tidal carbon dioxide (COJ occuwed in an anesthetized male who was placed in the head down position during radical perineal prostatectomy. The end-tidal CO, was restored after insertion of a wet pack into the operative site, which strongly indicated venous air embolism as the cause. Predisposing factors, detection, and treatment of venous air embolism in this setting are discussed. 0 I996 by Elsevier Science Inc. Keywords: Air embolism: venous; patient position: extreme, lithotomy Trendelenburg; prostatectomy, radical perineal.
Introduction Venous air embolism is a rarely reported complication of urologic surgery. Serious cases have occurred during transurethral, transvesical, and radical retropubic prostaTo our knowledge, its manifestation during tectomyF4 radical prostatic surgery via the perineal approach has not been previously described. We report a case th[at occurred in an otherwise healthy patient.
Case Report A 72-year-old, 70-kg man, diagnosed with locahzed adenocarcinoma of the prostate, was scheduled to undergo radi-
*Resident in Anesthesiology jClinica1 Assistant Professor of Anesthesiology $Assistant Professor of Anesthesiology §Clinical Assistant Professor of Urology Address correspondence to Dr. Lyew at the Anesthesiology Service, V.A. Medical Center, 3495 Bailey Avenue, Buffalo, NY, 14215, USA. Received for publication November 15, 1995; revised manuscript cepted for publication Februaq 9, 1996.
Journal of Clinical Anesthesia 8:659-661. 1996 0 1996 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
ac-
and Department
of Urology, State University of New
cal perineal prostatectomy. He had no significant cardiac or pulmonary disease, and no cardiac murmurs were heard on preoperative examination. Oral ferrous sulfate had previously been prescribed to cover donation of two units of autologous blood prior to surgery. The hemoglobin level was 10.3 g%, blood urea nitrogen 13 mg/dl, and creatinine 0.8 mg/dl. Chest radiography and electrocardiography (ECG) were within normal limits for his age. In the operating room, ASA standard monitoring was established. Large-bore peripheral intravenous (IV) catheters were inserted in both upper extremities. Anesthesia was induced with IV propofol and fentanyl. Endotracheal intubation was expedited with succinylcholine. Bilateral breath sounds and a normal expiratory capnogram were confirmed. Anesthesia was maintained with 50% nitrous oxide (N,O) in oxygen (0,)) isoflurane, and vecuronium. Ventilation was controlled. An esophageal stethoscope was inserted before the patient was placed in the exaggerated lithotomy position and in a 20” head down tilt. This action resulted in an increase in peak inflation pressure from 20 cm H,O to 28 cm H,O. The gravitational gradient between the perineum and the right atrium was estimated as 14 cm. The patient was kept well hydrated during surgery. Two hours after the start of the procedure, end-tidal carbon dioxide (CO,) abruptly decreased from 30 mmHg to 16 mmHg. Oxygen saturation as measured by pulse oximetry (SpO*) decreased from 100% to 88%. Blood pressure (BP) declined from 118/75 mmHg to 100/70 mmHg with little change in heart rate (HR). Ventilator settings were unchanged and the breathing circuit had no leaks or disconnection. N,O was turned off and the patient was ventilated with 100% 0,. Equal breath sounds without wheezing were present on auscultation. No cardiac murmurs were heard. Air was not detected in the peripheral IV lines on inspection. The surgeons were informed of the event. At that time, bleeding from the periprostatic venous plexus had largely stopped after dissection and separation
0952-8180/96/$15.00 PI1 SO952-8180(96)001742
Case Reports
of the prostate anteriorly from the bladder neck. A wet pack was inserted into the operative site two minutes after the changes in vital signs were first noted. Two minutes later, SpO, was 96% and BP was 123/70 mmHg. End-tidal CO, rose to 26 mmHg. An arterial blood gas sample was obtained at this time, which showed a pH of 7.27, pC0, of 47 mmHg, pa0, of 125 mmHg, bicarbonate of 21.1 mEq/ L, base excess minus 5, and SaO, of 98%. After an additional 10 minutes, SpO, was 100%. After this event, air-O, was used instead of N,O-0, to maintain isoflurane anesthesia. The remainder of the operation was uneventful. The estimated blood loss was 1.4 L and was replaced with autologous blood and lactated Ringer’s solution. The patient was awake on extubation without respiratory or neurologic symptoms at the end of the procedure, which lasted four hours. A postoperative chest radiograph showed essentially no changes from his previous chest study.
Discussion Radical perineal prostatectomy has become popular as an alternative to radical retropubic prostatectomy for the treatment of localized carcinoma of the prostate. Blood loss is lower during radical perineal prostatectomy because the deep dorsal venous complex of the penis, which is disturbed during radical retropubic prostatectomy, is avoided. The perineal approach results in a relatively avascular field for dissection. It provides good exposure for reconstruction of the vesicourethral anastomosis, whereas this procedure can be difficult with the retropubic approach. Thus, operative time and the number and frequency of homologous transfusions, with the risk of transmission of blood-borne viruses and transfusion reactions, are reduced. The operative time is similar to that for radical retropubic prostatectomy if staging pelvic lymph node dissection and repositioning for radical perineal prostatectomy are included.5-’ The causes of an abrupt decrease in end-tidal CO, during surgery include air embolism, a sudden increase in ventilation, a marked decrease in cardiac output, and an anesthesia circuit leak or disconnection that allows the ingress of air.* The latter three factors were excluded in our patient. In particular, hydration was maintained up to the time that the decrease in end-tidal CO, was noted. Recovery of end-tidal CO, and vital signs, after placement of the wet pack into the operative site, strongly suggests that venous air embolism was the cause of their transient decline. Several factors that favor a diagnosis of venous air embolism were present in this case. The Trendelenburg POsition causes the perineal operative field to be located above the level of the right atrium. A gravitational gradient of as little as 5 cm H,O is sufficient to allow air entry via the
*Larson CP Jr: Controversies in neurosurgical anesthesia. In: ASA Annual Refresher Course Lectures, 1984. Park Ridge, IL: American Society of Anesthesiologists 1984;302:1-6. 660
J. Clin. Anesth., vol. 8, December 1996
open veins.8 The gradient is increased if hypovolemia from surgical blood loss is inadequately compensated, causing a decrease in central venous pressure and a greater risk of venous air embolism. The prostatic bed is a richly vascular area that is prone to damage during operations in this vicinity. Depending on its concentration in the inspired gas mixture, N,O will increase the size of entrained air bubbles.g On the other hand, abdominal compression, caused by the exaggerated lithotomy position, may impede venous drainage from the surgical site and reduce the amount of air that is entrained. Venous air emboli of small size may be more common than suspected during prostatic surgery.lX4 Many of these emboli are of little significance. If patient positioning can create a gravitational gradient, Albin et aL4 have recommended that a precordial Doppler and a multi-orificed central venous catheter should be used, respectively, to detect and remove entrained air. The amount of air that is detectable with the Doppler is much less than that which causes a change in end-tidal CO, or pulmonary artery (PA) pressure. The Doppler signal is immediate whereas end-tidal CO, and PA pressure responses are delayed (15 to 30 seconds) .l” Fong et aZ.‘l found a perfect correlation between the precordial Doppler and two-dimensional echocardiography (kappa value = 1) in detecting embolic events during cesarean section. These events were shown by Doppler to be caused by air and not by amniotic fluid or thromboemboli.” The Doppler signal is not quantitative, as it is sensitive to both the volume of air moving within the heart and that which is trapped in the cardiac chambers. The device has been regarded as having excessive sensitivity, because it can detect minute air emboli that cause no respiratory or hemodynamic changes.? A combination of ultrasonic Doppler and end-tidal CO, monitoring may be more useful in detecting early and clinically significant venous air embolism.* Venous air embolism has also been reported to cause an increase in airway pressure during controlled ventilation,” but this action would be obscured by prior elevation as a result of chest and abdominal compression due to the exaggerated lithotomy and Trendelenburg positions. Simple airway pressure monitoring was found to be inferior to end-tidal CO, for the early detection of venous air embolism.13 Few studies have investigated the use of the multiorificed catheter to retrieve embolic air entering the heart via the inferior vena cava (IVC). In prone dogs with the abdomen free, a greater proportion of air was aspirated with the catheter in the superior right atrium (RA) than with it in the inferior RA. Survival from venous air embolism was not improved over that of an untreated group. 14,15With the abdomen compressed, aspiration of air and the success rate of resuscitation was increased with the catheter in the superior RA16 This is due to positive IVC and intrathoracic pressure at end-expiration, which opposes the localization of air at the IVC-RA junction and
TCucchiara RE’:Positioning the neurosurgical patient: special considerations. In: ASA Annual Rejkher Course Lectures, 1984. Park Ridge, IL: American Society of Anesthesiologists 1984;116:1-6.
Embolism during radical perineal prostatectomy Jollijfi et al.
its movement through the tricuspid valve, and favors its passage into the superior RA, where it is available for retrieval. Aspiration is reduced, however, if the catheter lies below the level of the air, and may be improved with a balloon catheter that rises into its vicinity.“’ However, when compared in vitro with other types of central venous catheters, the balloon catheter offered no advantage in retrieving air from an inclined cardiac model. Balloon inflation was found to impede contact of air with the catheter orificesi’ To our knowledge, the usefulness of a central catheter placed in the IVC to retrieve air travelling via this route has not been reported. We suggest that a multi-orificed catheter be used selectively during radical perineal prostatectomy, whereas a noninvasive precordial Doppler should be routinely employed because of the gravitational gradient. No air was retrievable during radical retropubic prostatectomy when venous air embolism was detected only with a Doppler and no decrease in end-tidal CO, was seen4 This type of venous air embolism probably occurs in many cases of radical perineal prostatectomy without incident and, hence, does not justify routine placement of a central catheter in an otherwise normal patient. If a decrease in end-tidal CO, occurs, the Doppler device can confirm venous air embolism as the cause, thus shortening the response time for specific therapy, as was described. The operating table can also be levelled to reduce the gravitational gradient. If the decreased end-tidal CO, persists, central access can be established expeditiously via the internal jugular vein for air aspiration, as the patient’s neck is accessible during surgery. Perioperative central venous access and invasive monitoring are more clearly indicated in the patient with poor cardiopulmonary reserves in whom venous air embolism may cause increased hemodynamic upset. Prompt therapy, on recognition of the early signs of venous air embolism, may prevent progression to more serious consequences.
References 1. Vacanti CA, Lodhia KL: Fatal massive air embolism during transurethral resection of the prostate. Anesthesiology 1991;74:186-7. 2. Salo M: Fatal air embolism during transvesical prostatectomy. Ann Chir CynaecolFenn 1971;60:151-3.
3. Razvi HA, Chin JL, Bhandari R: Fatal air embolism during radical retropubic prostatectomy. J Ural 1994;151:433-4. 4. AIbin MS, Ritter RR, Reinhart R, Erickson D, Rockwood A: Venous air embolism during radical retropubic prostatectomy. Anesth Analg 1992;74:151-3. 5. Thrasher JB, Paulson DF: Reappraisal of radical perineal prostatectomy. Eur Ural 1992;22:1-8. 6. Frazier HA, Robertson JE, Paulson DF: Radical prostatectomy: the pros and cons of the perineal versus retropubic approach. J uroz 1992;147(3 Pt 2):888-90. 7. Haab F, Boccon-Gibod L, Delmas V, Boccon-Gibod L, Toublanc M: Perineal versus retropubic radical prostatectomy for Tl, T2 prostate cancer. BrJ Ural 1994$4:626-g. 8. Albin MS, Carroll RG, Maroon JC: Clinical considerations concerning detection of venous air embolism. Neurosurgery 19783: 380-4. 9. McNiece WL: Air embolism. In: Stoelting RK, Barash PG, Gallagher TJ (eds): Advances in Anesthesia, vol. 4. Chicago: Year Book Publishers, 1987:151-84. 10. Chang JL, AIbin MS, Bunegin L, Hung TK: Analysis and comparison of venous air embolism detection methods. Neurosurgery 1980;7:135-41. 11. Fong J, Gadalla F, Pierri MK, Drurin M: Are Doppler-detected venous emboli during cesarean section air emboli? Anesth Analg 1990;71:254-7. 12. Sloan TB, Kimovec MA: Detection of venous air embolism by airway pressure monitoring. Anesthesiology 1986;64:645-7. 13. Dash HH, Bithal PK, Joshi S, Saini SS: Airway pressure monitoring as an aid in the diagnosis of air embolism. J Neurosurg Anesthesiol1993;5:159-63. 14. Artru AA: Venous air embolism in prone dogs positioned with the abdomen hanging freely: percentage of gas retrieved and success rate of resuscitation. Anesth A&g 1992;75:715-9. 15. Artru AA: Placement of a multi-orificed catheter in the inferior portion of the right atrium; percentage of gas retrieved and success rate of resuscitation after venous air embolism in prone dogs positioned with the abdomen hanging freely. Anesth Analg 1994; 79:740-4. 16. Colley PS, Artru AA: Bunegin-Albin catheter improves air retrieval and resuscitation from lethal venous air embolism in dogs. Anesth Analg 1987;66:991-4. 17. Albin MS, Ritter RR, Bunegin L: Venous air embolism during spinal instrumentation and fusion in the prone position [Letter], Anesth Analg 1992;75:152. 18. Hanna PG, Gravenstein N, Pashayan AG: In vitro comparison of central venous catheters for aspiration of venous air embolism: effect of catheter type, catheter tip position, and cardiac inclination. J Clin An&h 1991;3:290-4.
J. Clin. Anesth., vol. 8, December
1996
661
Venous Air Embolism during Radical Perineal Prostatectomy Michael P. Jolliffe, MD, * Michael A. Lyew, MB, F’RCA,t Ines H. Berger, MD,: Thomas Grimakli, ha>$ Department of Anesthesiology York at Buffalo, Buffalo, NY.
An abrupt decrease in end-tidal carbon dioxide (COJ occuwed in an anesthetized male who was placed in the head down position during radical perineal prostatectomy. The end-tidal CO, was restored after insertion of a wet pack into the operative site, which strongly indicated venous air embolism as the cause. Predisposing factors, detection, and treatment of venous air embolism in this setting are discussed. 0 I996 by Elsevier Science Inc. Keywords: Air embolism: venous; patient position: extreme, lithotomy Trendelenburg; prostatectomy, radical perineal.
Introduction Venous air embolism is a rarely reported complication of urologic surgery. Serious cases have occurred during transurethral, transvesical, and radical retropubic prostaTo our knowledge, its manifestation during tectomyF4 radical prostatic surgery via the perineal approach has not been previously described. We report a case th[at occurred in an otherwise healthy patient.
Case Report A 72-year-old, 70-kg man, diagnosed with locahzed adenocarcinoma of the prostate, was scheduled to undergo radi-
*Resident in Anesthesiology jClinica1 Assistant Professor of Anesthesiology $Assistant Professor of Anesthesiology §Clinical Assistant Professor of Urology Address correspondence to Dr. Lyew at the Anesthesiology Service, V.A. Medical Center, 3495 Bailey Avenue, Buffalo, NY, 14215, USA. Received for publication November 15, 1995; revised manuscript cepted for publication Februaq 9, 1996.
Journal of Clinical Anesthesia 8:659-661. 1996 0 1996 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
ac-
and Department
of Urology, State University of New
cal perineal prostatectomy. He had no significant cardiac or pulmonary disease, and no cardiac murmurs were heard on preoperative examination. Oral ferrous sulfate had previously been prescribed to cover donation of two units of autologous blood prior to surgery. The hemoglobin level was 10.3 g%, blood urea nitrogen 13 mg/dl, and creatinine 0.8 mg/dl. Chest radiography and electrocardiography (ECG) were within normal limits for his age. In the operating room, ASA standard monitoring was established. Large-bore peripheral intravenous (IV) catheters were inserted in both upper extremities. Anesthesia was induced with IV propofol and fentanyl. Endotracheal intubation was expedited with succinylcholine. Bilateral breath sounds and a normal expiratory capnogram were confirmed. Anesthesia was maintained with 50% nitrous oxide (N,O) in oxygen (0,)) isoflurane, and vecuronium. Ventilation was controlled. An esophageal stethoscope was inserted before the patient was placed in the exaggerated lithotomy position and in a 20” head down tilt. This action resulted in an increase in peak inflation pressure from 20 cm H,O to 28 cm H,O. The gravitational gradient between the perineum and the right atrium was estimated as 14 cm. The patient was kept well hydrated during surgery. Two hours after the start of the procedure, end-tidal carbon dioxide (CO,) abruptly decreased from 30 mmHg to 16 mmHg. Oxygen saturation as measured by pulse oximetry (SpO*) decreased from 100% to 88%. Blood pressure (BP) declined from 118/75 mmHg to 100/70 mmHg with little change in heart rate (HR). Ventilator settings were unchanged and the breathing circuit had no leaks or disconnection. N,O was turned off and the patient was ventilated with 100% 0,. Equal breath sounds without wheezing were present on auscultation. No cardiac murmurs were heard. Air was not detected in the peripheral IV lines on inspection. The surgeons were informed of the event. At that time, bleeding from the periprostatic venous plexus had largely stopped after dissection and separation
0952-8180/96/$15.00 PI1 SO952-8180(96)001742
Case Reports
of the prostate anteriorly from the bladder neck. A wet pack was inserted into the operative site two minutes after the changes in vital signs were first noted. Two minutes later, SpO, was 96% and BP was 123/70 mmHg. End-tidal CO, rose to 26 mmHg. An arterial blood gas sample was obtained at this time, which showed a pH of 7.27, pC0, of 47 mmHg, pa0, of 125 mmHg, bicarbonate of 21.1 mEq/ L, base excess minus 5, and SaO, of 98%. After an additional 10 minutes, SpO, was 100%. After this event, air-O, was used instead of N,O-0, to maintain isoflurane anesthesia. The remainder of the operation was uneventful. The estimated blood loss was 1.4 L and was replaced with autologous blood and lactated Ringer’s solution. The patient was awake on extubation without respiratory or neurologic symptoms at the end of the procedure, which lasted four hours. A postoperative chest radiograph showed essentially no changes from his previous chest study.
Discussion Radical perineal prostatectomy has become popular as an alternative to radical retropubic prostatectomy for the treatment of localized carcinoma of the prostate. Blood loss is lower during radical perineal prostatectomy because the deep dorsal venous complex of the penis, which is disturbed during radical retropubic prostatectomy, is avoided. The perineal approach results in a relatively avascular field for dissection. It provides good exposure for reconstruction of the vesicourethral anastomosis, whereas this procedure can be difficult with the retropubic approach. Thus, operative time and the number and frequency of homologous transfusions, with the risk of transmission of blood-borne viruses and transfusion reactions, are reduced. The operative time is similar to that for radical retropubic prostatectomy if staging pelvic lymph node dissection and repositioning for radical perineal prostatectomy are included.5-’ The causes of an abrupt decrease in end-tidal CO, during surgery include air embolism, a sudden increase in ventilation, a marked decrease in cardiac output, and an anesthesia circuit leak or disconnection that allows the ingress of air.* The latter three factors were excluded in our patient. In particular, hydration was maintained up to the time that the decrease in end-tidal CO, was noted. Recovery of end-tidal CO, and vital signs, after placement of the wet pack into the operative site, strongly suggests that venous air embolism was the cause of their transient decline. Several factors that favor a diagnosis of venous air embolism were present in this case. The Trendelenburg POsition causes the perineal operative field to be located above the level of the right atrium. A gravitational gradient of as little as 5 cm H,O is sufficient to allow air entry via the
*Larson CP Jr: Controversies in neurosurgical anesthesia. In: ASA Annual Refresher Course Lectures, 1984. Park Ridge, IL: American Society of Anesthesiologists 1984;302:1-6. 660
J. Clin. Anesth., vol. 8, December 1996
open veins.8 The gradient is increased if hypovolemia from surgical blood loss is inadequately compensated, causing a decrease in central venous pressure and a greater risk of venous air embolism. The prostatic bed is a richly vascular area that is prone to damage during operations in this vicinity. Depending on its concentration in the inspired gas mixture, N,O will increase the size of entrained air bubbles.g On the other hand, abdominal compression, caused by the exaggerated lithotomy position, may impede venous drainage from the surgical site and reduce the amount of air that is entrained. Venous air emboli of small size may be more common than suspected during prostatic surgery.lX4 Many of these emboli are of little significance. If patient positioning can create a gravitational gradient, Albin et aL4 have recommended that a precordial Doppler and a multi-orificed central venous catheter should be used, respectively, to detect and remove entrained air. The amount of air that is detectable with the Doppler is much less than that which causes a change in end-tidal CO, or pulmonary artery (PA) pressure. The Doppler signal is immediate whereas end-tidal CO, and PA pressure responses are delayed (15 to 30 seconds) .l” Fong et aZ.‘l found a perfect correlation between the precordial Doppler and two-dimensional echocardiography (kappa value = 1) in detecting embolic events during cesarean section. These events were shown by Doppler to be caused by air and not by amniotic fluid or thromboemboli.” The Doppler signal is not quantitative, as it is sensitive to both the volume of air moving within the heart and that which is trapped in the cardiac chambers. The device has been regarded as having excessive sensitivity, because it can detect minute air emboli that cause no respiratory or hemodynamic changes.? A combination of ultrasonic Doppler and end-tidal CO, monitoring may be more useful in detecting early and clinically significant venous air embolism.* Venous air embolism has also been reported to cause an increase in airway pressure during controlled ventilation,” but this action would be obscured by prior elevation as a result of chest and abdominal compression due to the exaggerated lithotomy and Trendelenburg positions. Simple airway pressure monitoring was found to be inferior to end-tidal CO, for the early detection of venous air embolism.13 Few studies have investigated the use of the multiorificed catheter to retrieve embolic air entering the heart via the inferior vena cava (IVC). In prone dogs with the abdomen free, a greater proportion of air was aspirated with the catheter in the superior right atrium (RA) than with it in the inferior RA. Survival from venous air embolism was not improved over that of an untreated group. 14,15With the abdomen compressed, aspiration of air and the success rate of resuscitation was increased with the catheter in the superior RA16 This is due to positive IVC and intrathoracic pressure at end-expiration, which opposes the localization of air at the IVC-RA junction and
TCucchiara RE’:Positioning the neurosurgical patient: special considerations. In: ASA Annual Rejkher Course Lectures, 1984. Park Ridge, IL: American Society of Anesthesiologists 1984;116:1-6.
Embolism during radical perineal prostatectomy Jollijfi et al.
its movement through the tricuspid valve, and favors its passage into the superior RA, where it is available for retrieval. Aspiration is reduced, however, if the catheter lies below the level of the air, and may be improved with a balloon catheter that rises into its vicinity.“’ However, when compared in vitro with other types of central venous catheters, the balloon catheter offered no advantage in retrieving air from an inclined cardiac model. Balloon inflation was found to impede contact of air with the catheter orificesi’ To our knowledge, the usefulness of a central catheter placed in the IVC to retrieve air travelling via this route has not been reported. We suggest that a multi-orificed catheter be used selectively during radical perineal prostatectomy, whereas a noninvasive precordial Doppler should be routinely employed because of the gravitational gradient. No air was retrievable during radical retropubic prostatectomy when venous air embolism was detected only with a Doppler and no decrease in end-tidal CO, was seen4 This type of venous air embolism probably occurs in many cases of radical perineal prostatectomy without incident and, hence, does not justify routine placement of a central catheter in an otherwise normal patient. If a decrease in end-tidal CO, occurs, the Doppler device can confirm venous air embolism as the cause, thus shortening the response time for specific therapy, as was described. The operating table can also be levelled to reduce the gravitational gradient. If the decreased end-tidal CO, persists, central access can be established expeditiously via the internal jugular vein for air aspiration, as the patient’s neck is accessible during surgery. Perioperative central venous access and invasive monitoring are more clearly indicated in the patient with poor cardiopulmonary reserves in whom venous air embolism may cause increased hemodynamic upset. Prompt therapy, on recognition of the early signs of venous air embolism, may prevent progression to more serious consequences.
References 1. Vacanti CA, Lodhia KL: Fatal massive air embolism during transurethral resection of the prostate. Anesthesiology 1991;74:186-7. 2. Salo M: Fatal air embolism during transvesical prostatectomy. Ann Chir CynaecolFenn 1971;60:151-3.
3. Razvi HA, Chin JL, Bhandari R: Fatal air embolism during radical retropubic prostatectomy. J Ural 1994;151:433-4. 4. AIbin MS, Ritter RR, Reinhart R, Erickson D, Rockwood A: Venous air embolism during radical retropubic prostatectomy. Anesth Analg 1992;74:151-3. 5. Thrasher JB, Paulson DF: Reappraisal of radical perineal prostatectomy. Eur Ural 1992;22:1-8. 6. Frazier HA, Robertson JE, Paulson DF: Radical prostatectomy: the pros and cons of the perineal versus retropubic approach. J uroz 1992;147(3 Pt 2):888-90. 7. Haab F, Boccon-Gibod L, Delmas V, Boccon-Gibod L, Toublanc M: Perineal versus retropubic radical prostatectomy for Tl, T2 prostate cancer. BrJ Ural 1994$4:626-g. 8. Albin MS, Carroll RG, Maroon JC: Clinical considerations concerning detection of venous air embolism. Neurosurgery 19783: 380-4. 9. McNiece WL: Air embolism. In: Stoelting RK, Barash PG, Gallagher TJ (eds): Advances in Anesthesia, vol. 4. Chicago: Year Book Publishers, 1987:151-84. 10. Chang JL, AIbin MS, Bunegin L, Hung TK: Analysis and comparison of venous air embolism detection methods. Neurosurgery 1980;7:135-41. 11. Fong J, Gadalla F, Pierri MK, Drurin M: Are Doppler-detected venous emboli during cesarean section air emboli? Anesth Analg 1990;71:254-7. 12. Sloan TB, Kimovec MA: Detection of venous air embolism by airway pressure monitoring. Anesthesiology 1986;64:645-7. 13. Dash HH, Bithal PK, Joshi S, Saini SS: Airway pressure monitoring as an aid in the diagnosis of air embolism. J Neurosurg Anesthesiol1993;5:159-63. 14. Artru AA: Venous air embolism in prone dogs positioned with the abdomen hanging freely: percentage of gas retrieved and success rate of resuscitation. Anesth A&g 1992;75:715-9. 15. Artru AA: Placement of a multi-orificed catheter in the inferior portion of the right atrium; percentage of gas retrieved and success rate of resuscitation after venous air embolism in prone dogs positioned with the abdomen hanging freely. Anesth Analg 1994; 79:740-4. 16. Colley PS, Artru AA: Bunegin-Albin catheter improves air retrieval and resuscitation from lethal venous air embolism in dogs. Anesth Analg 1987;66:991-4. 17. Albin MS, Ritter RR, Bunegin L: Venous air embolism during spinal instrumentation and fusion in the prone position [Letter], Anesth Analg 1992;75:152. 18. Hanna PG, Gravenstein N, Pashayan AG: In vitro comparison of central venous catheters for aspiration of venous air embolism: effect of catheter type, catheter tip position, and cardiac inclination. J Clin An&h 1991;3:290-4.
J. Clin. Anesth., vol. 8, December
1996
661