Pneumopericardium Associated with Laparoscopy
Gundy B. Knos, MD ,* Yung-Fong Andrew Toledo MDz# Departntent
of Anesthesiology,
This case report describes a rare but potentially serieus complication of pneumopericardium occurring during diagnostic laparoscopy. Contributing factors and possible etiologies are discussed. Keywords: Pneumopericardium;
laparoscopy.
Introduction Laparoscopy is a common procedure that has gained popularity because it is associated with lower morbidity and mortality rates than exploratory laparotomy’.’ and because it spares the patient a major surgical procedure.’ However, there have been reports of complications associated with laparoscopy.‘m5 Many of these
*Assistant Professor
of Anesthesia, of Anesthesiology
Division
of Ambulatory
Sur-
tAssociaLe Professor of Anesthesia, gery, Department of Anesthesiology
Division
of Ambulatory
Sur-
gery,
Department
SAssistant
Professor,
Department
of GynecologyiObstetrics
Address reprint requests to Dr. Knos at the Department of Anesthesiology, Emory Clinic, 1327 Clifton Road NE, Atlanta, GA 30322, USA. Received for publication July 20, 1989; cepted for publication July 18, 1990. 0 199
56
revised
manuscript
1 Butterworth-Heinemann
J. Clin. Anesth., vol. 3, January/February
1YYl
ac-
Sung, MD,_F
Emory C’niversity School of Medicine,
Atlanta,
complications are related to the spread of insufflating gas to several body compartments, creating subcutaneous, retroperitoneal, and omental emphysema, pneumomediastinum, pneumothorax, and air embolism.” Since these procedures are often performed on outpatients, the anesthesiologist and surgeon need to be aware of the potentially life-threatening complications that can occur with this procedure prior to discharging patients. There have been two reports of pneumopericardium associated with diagnostic laparoscopy prior to this ene.“,:’ A third patient with laparoscopyassociated pneumopericardium is described here.
Case Report The patient was a 34-year-old, 163 cm, and 5ti kg woman with the diagnosis of infertility. She was scheduled for laparoscopy with possible laser excision of adhesions and endometrial biopsy. Physical examination and preoperative laboratory tests were unremarkable, and she was classifled as ASA physical status 1. Two 400 mg cimetidine caplets were given to the patient to be taken the night before and on the morning of surgery. An electrocardiogram (EKG), automatie blood pressure (BP) cuff (Life Stat 200 Physiocontrol Blood Pressure Monitor, Redmond, WA), precordial stethoscope, peripheral nerve stimulator (Digistim 11, Houston, TX), and pulse oximeter (Ohmeda 3700, Boulder, CO) were attached to the patient on arrival of anesin the operating room. Prior to induction thesia, the patient received 3 mg of d-tubocurarine,
1 mg of midazolam, and 25 l.r,g of fentanyl intravenously (IV). Induction followed with IV thiopental sodium 350 mg, lidocaine 100 mg, and succinylcholine 120 mg. The patient was smoothly intubated witb a 7.5 mm internal diameter oral endotracheal tube. On auscultation of the chest, breath sounds were equal and bilateral. The stomach was suctioned with an oralgastric tube, an esophageal stethoscope was placed, and a capnometer (Hewlett-Packard 472 lOA, Waltham, MA) was attached to the oral endotracheal tube. The bladder was catheterized. Anesthesia was maintained with isoflurane 1% to 2%, nitrous oxide (N,O) 60%, and oxygen (0,) 40%. The patient was given 15 mg of atracurium for muscle relaxation, and an additional 25 kg of fentanyl and 0.5 ml of droperidol (1.25 mg) were administered IV. The patient also received 30 mg of codeine intramuscularly (IM) and 1 g of cefazolin sodium IV during the procedure. Intermittent positive pressure ventilation was instituted at a respiratory rate (RR) of 6 breaths/minute with a tidal volume of 750 ml. The initial peak inspiratory pressures were 20 cm of water (H,O). Oxygen saturation levels were maintained between 98% and 100% throughout the procedure. A Verres needle was easily placed in the peritoneal cavity, and 3 liters of carbon dioxide (CO,) were introduced via standard transumbilical technique. Intra-abdominal pressure as measured by the CO, insufflator (R. Wolf Model 2043.5, Rosemont, IL) varied between 10 and 20 mmHg. The peak inspiratory pressure increased to 30 cm of H,O. As the end-tidal CO, increased from 30 mmHg to 35 mmHg, ventilation was increased to 9 breathsiminute with a tidal volume of 840 ml. The patient was placed simultaneously in the Trendelenburg and lithotomy positions. The laparoscopic trocar and Olympus laser laparoscope were introduced without difficulty. Laser ablation of several areas of endometriosis proceeded uneventfully with a Sharplan 1040 CO, laser (Tel Aviv, Israel). The abdomen was refilled with rapid insufflation of 3 liters of CO, several times during the laser surgery to replenish the smoke-filled CO, removed by suction. The case proceeded uneventfully for 2.5 hours. Systolic pressure (SP) remained stable between 110 and 120 mmHg, and diastolic pressure remained stable between 60 and 80 mmHg. Heart rate (HR) averaged 95 beatslminute. Muscle relaxation was reversed with neostigmine 3 mg IV and glycopyrrolate 0.6 mg IV, and the patient was extubated easily with good spontaneous ventilation. In the recovery room, the patient had diffuse subcutaneous emphysema extending from the groin and abdomen to the anterior chest wal1 and into the neck and upper arms. With rather severe shivering, initial
RP was 170/100 mmHg with an HR of 120 heats/ minute. Respiration was 24 breathsjminute. Breath sounds were clear and equal bilaterally. 0, saturation was 100% on a 5-liter 0, face shield (FIO, 40% to 50%). In spite of shivering, the patient was in no apparent distress. An arterial blood sample was drawn for blood gas analysis, which showed a partial pressure of 0, (PO,) of 329 mmHg, partial pressure of CO, (PCO,) of 40 mmHg, and pH of 7.30. A portable chest radiograph showed both lungs fully inflated with subcutaneous emphysema on both sides of the chest, neck, note was a and upper arms cF@re 1). Of particular band of emphysema outlining the cardiac silhouette {Figure 2). As the patient’s shivering diminished, it was possible to hear a loud mediastinal crunch with systolic and diastolic components. The patient remained stable in the recovery room and was admitted to the hospita1 for observation overnight. The chest radiograph taken upon admission to the hospital, 3% hours after the radiograph taken in the recovery room, showed resolution of the subcutaneous emphysema and only a faint trace of the unpericardial air (Figure 3). The patient recovered remarkably and was discharged the following day.
Discussion The mortality rate during laparoscopy has been previously reported as 3 per 12,000 cases4 and 1 per 8,000
Figure 1. Portable chest radiograph in sitting position taken in recovery room showing subcutaneous emphysema, subdiaphragmatic air, and pneumopericardium (white arrows). The metallic object overlying the left chest wal1 is part of the blood pressure cuff. J. Clin. Anesth., vol. 3, JanuaryIFebruary
1991
57
Cuse Reports
Figure 2. Enlargement of recovery room chest radiograph. The white arrows indicate the radiolucency of the pneumopericardium.
cases,5 with cardiac arrest occurring as frequently as 1 per 2,000 cases. 5 Clearly, if these statistics are accurate today, the mortality rate for laparoscopy is higher than the usually quoted fïgure of 1 death per 10,000 anesthetics cited by Tinker and Roberts.” CO, is often used to produce a pneumoperitoneum, since it is the most blood soluble of the agents (CO,, N20, and air) used for this purpose.” N,O is 68% as soluble as CO, in blood; therefore, expansion of a CO,-fïlled space with N,O is not a serious problem. Also, CO, is less flammable than N,O.‘,” Air is five times more toxic than CO, when gas embolism occurs.5 Cardiac dysrhythmias during laparoscopy are common and are probably due to increased circulating catecholamine concentrations released in response to hypercarbia and surgical stimulation. Bradycardia due to vagal stimulation secondary to uterine manipulation also has been reported.5 There also have been reports of pneumothorax and pneumomediastinum after diagnostic laparoscopy1,7mY since its fìrst reported use in 190 1 .7 This situation has been attributed to the increased intra-abdominal pressure associated with the gas insufflation system. An intra-abdominal pressure of 25 mmHg translates to a force of about 30g/cm,’ or 0.5 lblin,’ on the abdominal structures.lO The total force on the diaphragm theoretically could exceed 50 kg.‘O These pressures may contribute to the occurrence of a pneumothorax in patients with hiatal hernias and congenital diaphragmatic defects. 5.g.11A tear also may occur in the visceral peritoneum during the procedure, allowing retroperitoneal dissection of the insufflating gas to the mediastinum. Rupture could occur through the 58
J. Clin. Anesth.,
vol. 3, JanuaryEebruary
1991
Figure 3. Chest radiograph taken 91/zhours aftel- the rccovery room portable chest radiograph, showing nearly complete resolution of subcutaneous emphysema and pneumopericardium.
mediastinal pleura or along the pulmonary vessels into the pleura1 space, producing a pneumothorax.H The same forces allowing for the formation of a pneumothorax could explain the pneumopericardium that occurred in this case. Subcutaneous emphysema was reported in the chest and neck of both the other patients who developed pneumopericardia.“.” In addition to these fìndings, the present patient also had involvement of the abdominal wall. Mediastinal air occurred in the other two patients with pneumopericardia but was not noted in this patient. The mechanism proposed by Nicholson and Berman” is that of insufflating gas forced through a diaphragmatic hiatus, such as that around the inferior vena cava, pushing gas into the mediastinum and pericardium. With increased insufflating pressures, the COcould track through a congenital defect in the membranous portion of the diaphragm, which has a communication in the embryo between the pericardial and peritoneal cavities. lp The present patient had no mediastinal air and no other obvious route for gas entry visible on the initial portable chest radiograph. An interesting common denominator in al1 three patients with pneumopericardia is that of subcutaneous emphysema involving the anterior chest and neck. One possible, though unlikely, route of gas dissection could be into the mediastinum from the upper anterior chest and neck. The syndrome of cardiac tamponade has been produced by tension pneumopericardium in situations
Pneumopericardium
associated with positive pressure mechanica1 ventilation or tension pneumothorax.‘3s’4 Although there have been no reports to date of a pneumopericardium producing cardiovascular collapse during diagnostic laparoscopy, the potential exists for enough gas to enter the relatively noncompliant pericardial sac to produce hemodynamic embarrassment. This situation could occur despite the compressibility of gas as compared to fluid, and the frequency and severity may be increased with increasing insufflating pressures. The anesthesiologist and surgeon caring for these patients should consider this complication in the patient who is hemodynamically unstable after diagnostic laparoscopy.
Acknowledgment The authors would like to acknowledge Dr. Robert L. DeHaan of the Emory University Department of Anatomy for his expert advice regarding the embryological origin and anatomy of the pericardium.
References 1. Doctor N, Hussain
Z: Bilateral
pneumothorax
associ-
Anaesthesia 1973;28:75-81. 2. Nicholson D, Berman N: Pneumopericardium following laparoscopy. Chest 1979;76:605-7. ated with laparoscopy.
after lapar« .~opy: Knos et al.
3. Herrerias J, Ariza A, Garrido M: An unusual complication of laparoscopy: pneumopericardium. Endoscojy 1980;12:254-5. 4. Williams P: Avoiding laparoscopy complications. Fe& Steril 1974;25:280-7. 5. Fishburne J: Anesthesia for laparoscopy: considerations, complications and techniques. J Reprod Med 1978;21:37-40. 6. Tinker J, Roberts S: Anesthesia risk. In: Miller R, ed. Anesthesia. Vol. 1, 2d ed. New York: Churchill Livingstone, 1986:368. 7. Leitao C, Mascarenhas F, Neto F, Lamaz J, Noronha M, Bordalo 0: Laparoscopy: diagnostic experience in 300 patient studies. Am J Gastroenterol 1976;66: 155-9. 8. Smiler B, Falick Y: ComplicaGon during anesthesia and laparoscopy. JAMA 1973;226:676. 9. Batra M, Driscoll J, Coburn W, Marks W: Evanescent nitrous oxide pneumothorax after laparoscopy. Anesth Analg 1983;62: 1121-3. 10. Seed R, Shakespeare T, Muldoon M: Carbon dioxide homeostasis during anesthesia for laparoscopy. Anaesthesis 1970;25:223-31. 11. Keith L, Silver A, Becker M: Anesthesia for laparoscopy. J Reprod Med 1974;12:227-33. 12. Langman J: Medical Embryology. Baltimore: Williams & Wilkins, 1963:235-7. 13. McCaughey W, King R: Pneumopericardium associated with trachea1 rupture. Anaesthesia 1975;30:199205. 14. Westaby S: Pneumopericardium and tension pneumopericardium after closed-chest injury. Thorax 1977;32:91-7.
J. Clin. Anesth.,
vol. 3, JanuaryiFebruary
1991
59
Gundy B. Knos, MD ,* Yung-Fong Andrew Toledo MDz# Departntent
of Anesthesiology,
This case report describes a rare but potentially serieus complication of pneumopericardium occurring during diagnostic laparoscopy. Contributing factors and possible etiologies are discussed. Keywords: Pneumopericardium;
laparoscopy.
Introduction Laparoscopy is a common procedure that has gained popularity because it is associated with lower morbidity and mortality rates than exploratory laparotomy’.’ and because it spares the patient a major surgical procedure.’ However, there have been reports of complications associated with laparoscopy.‘m5 Many of these
*Assistant Professor
of Anesthesia, of Anesthesiology
Division
of Ambulatory
Sur-
tAssociaLe Professor of Anesthesia, gery, Department of Anesthesiology
Division
of Ambulatory
Sur-
gery,
Department
SAssistant
Professor,
Department
of GynecologyiObstetrics
Address reprint requests to Dr. Knos at the Department of Anesthesiology, Emory Clinic, 1327 Clifton Road NE, Atlanta, GA 30322, USA. Received for publication July 20, 1989; cepted for publication July 18, 1990. 0 199
56
revised
manuscript
1 Butterworth-Heinemann
J. Clin. Anesth., vol. 3, January/February
1YYl
ac-
Sung, MD,_F
Emory C’niversity School of Medicine,
Atlanta,
complications are related to the spread of insufflating gas to several body compartments, creating subcutaneous, retroperitoneal, and omental emphysema, pneumomediastinum, pneumothorax, and air embolism.” Since these procedures are often performed on outpatients, the anesthesiologist and surgeon need to be aware of the potentially life-threatening complications that can occur with this procedure prior to discharging patients. There have been two reports of pneumopericardium associated with diagnostic laparoscopy prior to this ene.“,:’ A third patient with laparoscopyassociated pneumopericardium is described here.
Case Report The patient was a 34-year-old, 163 cm, and 5ti kg woman with the diagnosis of infertility. She was scheduled for laparoscopy with possible laser excision of adhesions and endometrial biopsy. Physical examination and preoperative laboratory tests were unremarkable, and she was classifled as ASA physical status 1. Two 400 mg cimetidine caplets were given to the patient to be taken the night before and on the morning of surgery. An electrocardiogram (EKG), automatie blood pressure (BP) cuff (Life Stat 200 Physiocontrol Blood Pressure Monitor, Redmond, WA), precordial stethoscope, peripheral nerve stimulator (Digistim 11, Houston, TX), and pulse oximeter (Ohmeda 3700, Boulder, CO) were attached to the patient on arrival of anesin the operating room. Prior to induction thesia, the patient received 3 mg of d-tubocurarine,
1 mg of midazolam, and 25 l.r,g of fentanyl intravenously (IV). Induction followed with IV thiopental sodium 350 mg, lidocaine 100 mg, and succinylcholine 120 mg. The patient was smoothly intubated witb a 7.5 mm internal diameter oral endotracheal tube. On auscultation of the chest, breath sounds were equal and bilateral. The stomach was suctioned with an oralgastric tube, an esophageal stethoscope was placed, and a capnometer (Hewlett-Packard 472 lOA, Waltham, MA) was attached to the oral endotracheal tube. The bladder was catheterized. Anesthesia was maintained with isoflurane 1% to 2%, nitrous oxide (N,O) 60%, and oxygen (0,) 40%. The patient was given 15 mg of atracurium for muscle relaxation, and an additional 25 kg of fentanyl and 0.5 ml of droperidol (1.25 mg) were administered IV. The patient also received 30 mg of codeine intramuscularly (IM) and 1 g of cefazolin sodium IV during the procedure. Intermittent positive pressure ventilation was instituted at a respiratory rate (RR) of 6 breaths/minute with a tidal volume of 750 ml. The initial peak inspiratory pressures were 20 cm of water (H,O). Oxygen saturation levels were maintained between 98% and 100% throughout the procedure. A Verres needle was easily placed in the peritoneal cavity, and 3 liters of carbon dioxide (CO,) were introduced via standard transumbilical technique. Intra-abdominal pressure as measured by the CO, insufflator (R. Wolf Model 2043.5, Rosemont, IL) varied between 10 and 20 mmHg. The peak inspiratory pressure increased to 30 cm of H,O. As the end-tidal CO, increased from 30 mmHg to 35 mmHg, ventilation was increased to 9 breathsiminute with a tidal volume of 840 ml. The patient was placed simultaneously in the Trendelenburg and lithotomy positions. The laparoscopic trocar and Olympus laser laparoscope were introduced without difficulty. Laser ablation of several areas of endometriosis proceeded uneventfully with a Sharplan 1040 CO, laser (Tel Aviv, Israel). The abdomen was refilled with rapid insufflation of 3 liters of CO, several times during the laser surgery to replenish the smoke-filled CO, removed by suction. The case proceeded uneventfully for 2.5 hours. Systolic pressure (SP) remained stable between 110 and 120 mmHg, and diastolic pressure remained stable between 60 and 80 mmHg. Heart rate (HR) averaged 95 beatslminute. Muscle relaxation was reversed with neostigmine 3 mg IV and glycopyrrolate 0.6 mg IV, and the patient was extubated easily with good spontaneous ventilation. In the recovery room, the patient had diffuse subcutaneous emphysema extending from the groin and abdomen to the anterior chest wal1 and into the neck and upper arms. With rather severe shivering, initial
RP was 170/100 mmHg with an HR of 120 heats/ minute. Respiration was 24 breathsjminute. Breath sounds were clear and equal bilaterally. 0, saturation was 100% on a 5-liter 0, face shield (FIO, 40% to 50%). In spite of shivering, the patient was in no apparent distress. An arterial blood sample was drawn for blood gas analysis, which showed a partial pressure of 0, (PO,) of 329 mmHg, partial pressure of CO, (PCO,) of 40 mmHg, and pH of 7.30. A portable chest radiograph showed both lungs fully inflated with subcutaneous emphysema on both sides of the chest, neck, note was a and upper arms cF@re 1). Of particular band of emphysema outlining the cardiac silhouette {Figure 2). As the patient’s shivering diminished, it was possible to hear a loud mediastinal crunch with systolic and diastolic components. The patient remained stable in the recovery room and was admitted to the hospita1 for observation overnight. The chest radiograph taken upon admission to the hospital, 3% hours after the radiograph taken in the recovery room, showed resolution of the subcutaneous emphysema and only a faint trace of the unpericardial air (Figure 3). The patient recovered remarkably and was discharged the following day.
Discussion The mortality rate during laparoscopy has been previously reported as 3 per 12,000 cases4 and 1 per 8,000
Figure 1. Portable chest radiograph in sitting position taken in recovery room showing subcutaneous emphysema, subdiaphragmatic air, and pneumopericardium (white arrows). The metallic object overlying the left chest wal1 is part of the blood pressure cuff. J. Clin. Anesth., vol. 3, JanuaryIFebruary
1991
57
Cuse Reports
Figure 2. Enlargement of recovery room chest radiograph. The white arrows indicate the radiolucency of the pneumopericardium.
cases,5 with cardiac arrest occurring as frequently as 1 per 2,000 cases. 5 Clearly, if these statistics are accurate today, the mortality rate for laparoscopy is higher than the usually quoted fïgure of 1 death per 10,000 anesthetics cited by Tinker and Roberts.” CO, is often used to produce a pneumoperitoneum, since it is the most blood soluble of the agents (CO,, N20, and air) used for this purpose.” N,O is 68% as soluble as CO, in blood; therefore, expansion of a CO,-fïlled space with N,O is not a serious problem. Also, CO, is less flammable than N,O.‘,” Air is five times more toxic than CO, when gas embolism occurs.5 Cardiac dysrhythmias during laparoscopy are common and are probably due to increased circulating catecholamine concentrations released in response to hypercarbia and surgical stimulation. Bradycardia due to vagal stimulation secondary to uterine manipulation also has been reported.5 There also have been reports of pneumothorax and pneumomediastinum after diagnostic laparoscopy1,7mY since its fìrst reported use in 190 1 .7 This situation has been attributed to the increased intra-abdominal pressure associated with the gas insufflation system. An intra-abdominal pressure of 25 mmHg translates to a force of about 30g/cm,’ or 0.5 lblin,’ on the abdominal structures.lO The total force on the diaphragm theoretically could exceed 50 kg.‘O These pressures may contribute to the occurrence of a pneumothorax in patients with hiatal hernias and congenital diaphragmatic defects. 5.g.11A tear also may occur in the visceral peritoneum during the procedure, allowing retroperitoneal dissection of the insufflating gas to the mediastinum. Rupture could occur through the 58
J. Clin. Anesth.,
vol. 3, JanuaryEebruary
1991
Figure 3. Chest radiograph taken 91/zhours aftel- the rccovery room portable chest radiograph, showing nearly complete resolution of subcutaneous emphysema and pneumopericardium.
mediastinal pleura or along the pulmonary vessels into the pleura1 space, producing a pneumothorax.H The same forces allowing for the formation of a pneumothorax could explain the pneumopericardium that occurred in this case. Subcutaneous emphysema was reported in the chest and neck of both the other patients who developed pneumopericardia.“.” In addition to these fìndings, the present patient also had involvement of the abdominal wall. Mediastinal air occurred in the other two patients with pneumopericardia but was not noted in this patient. The mechanism proposed by Nicholson and Berman” is that of insufflating gas forced through a diaphragmatic hiatus, such as that around the inferior vena cava, pushing gas into the mediastinum and pericardium. With increased insufflating pressures, the COcould track through a congenital defect in the membranous portion of the diaphragm, which has a communication in the embryo between the pericardial and peritoneal cavities. lp The present patient had no mediastinal air and no other obvious route for gas entry visible on the initial portable chest radiograph. An interesting common denominator in al1 three patients with pneumopericardia is that of subcutaneous emphysema involving the anterior chest and neck. One possible, though unlikely, route of gas dissection could be into the mediastinum from the upper anterior chest and neck. The syndrome of cardiac tamponade has been produced by tension pneumopericardium in situations
Pneumopericardium
associated with positive pressure mechanica1 ventilation or tension pneumothorax.‘3s’4 Although there have been no reports to date of a pneumopericardium producing cardiovascular collapse during diagnostic laparoscopy, the potential exists for enough gas to enter the relatively noncompliant pericardial sac to produce hemodynamic embarrassment. This situation could occur despite the compressibility of gas as compared to fluid, and the frequency and severity may be increased with increasing insufflating pressures. The anesthesiologist and surgeon caring for these patients should consider this complication in the patient who is hemodynamically unstable after diagnostic laparoscopy.
Acknowledgment The authors would like to acknowledge Dr. Robert L. DeHaan of the Emory University Department of Anatomy for his expert advice regarding the embryological origin and anatomy of the pericardium.
References 1. Doctor N, Hussain
Z: Bilateral
pneumothorax
associ-
Anaesthesia 1973;28:75-81. 2. Nicholson D, Berman N: Pneumopericardium following laparoscopy. Chest 1979;76:605-7. ated with laparoscopy.
after lapar« .~opy: Knos et al.
3. Herrerias J, Ariza A, Garrido M: An unusual complication of laparoscopy: pneumopericardium. Endoscojy 1980;12:254-5. 4. Williams P: Avoiding laparoscopy complications. Fe& Steril 1974;25:280-7. 5. Fishburne J: Anesthesia for laparoscopy: considerations, complications and techniques. J Reprod Med 1978;21:37-40. 6. Tinker J, Roberts S: Anesthesia risk. In: Miller R, ed. Anesthesia. Vol. 1, 2d ed. New York: Churchill Livingstone, 1986:368. 7. Leitao C, Mascarenhas F, Neto F, Lamaz J, Noronha M, Bordalo 0: Laparoscopy: diagnostic experience in 300 patient studies. Am J Gastroenterol 1976;66: 155-9. 8. Smiler B, Falick Y: ComplicaGon during anesthesia and laparoscopy. JAMA 1973;226:676. 9. Batra M, Driscoll J, Coburn W, Marks W: Evanescent nitrous oxide pneumothorax after laparoscopy. Anesth Analg 1983;62: 1121-3. 10. Seed R, Shakespeare T, Muldoon M: Carbon dioxide homeostasis during anesthesia for laparoscopy. Anaesthesis 1970;25:223-31. 11. Keith L, Silver A, Becker M: Anesthesia for laparoscopy. J Reprod Med 1974;12:227-33. 12. Langman J: Medical Embryology. Baltimore: Williams & Wilkins, 1963:235-7. 13. McCaughey W, King R: Pneumopericardium associated with trachea1 rupture. Anaesthesia 1975;30:199205. 14. Westaby S: Pneumopericardium and tension pneumopericardium after closed-chest injury. Thorax 1977;32:91-7.
J. Clin. Anesth.,
vol. 3, JanuaryiFebruary
1991
59
