Seminars in thoracic and cardiovascular surgery. Pediatric cardiac surgery annual, 2000
The objective of this review was to analyze a surgical strategy for children with anomalous origi... more The objective of this review was to analyze a surgical strategy for children with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) where aortic implantation was successful without the use of extracorporeal membrane oxygenation (ECMO) or left ventricular assist device (LVAD). From 1989 through 1999, 16 consecutive children underwent aortic implantation for ALCAPA. Median age was 0.45 years. Surgical strategy included bicaval venous cannulation, LV vent, moderate systemic hypothermia (28 degrees C), antegrade cardioplegia with pulmonary artery (PA) occlusion, PA transection, aortic implantation with a large "button" of PA, PA reconstruction with pericardium, intraoperative transesophageal echocardiography, and inotropic support with dopamine, dobutamine, and milrinone. All patients survived. No patient was placed on ECMO or LVAD. Mean cardiopulmonary bypass (CPB) time was 152 +/- 41 minutes. Mean aortic cross-clamp time was 46 +/- 13 minutes. M...
Fontan palliation is used when biventricular repair (BVR) is not possible. Early outcomes are acc... more Fontan palliation is used when biventricular repair (BVR) is not possible. Early outcomes are acceptable; however, the long-term sequelae include protein-losing enteropathy, declining functional status, increased pulmonary vascular resistance, heart failure, and hepatic and renal dysfunction. These adverse events are characteristic of persistent venous hypertension and may be avoided if restoring biventricular circulation is possible. Arrhythmias are a common adverse event, particularly in patients with an atriopulmonary connection, which may lead to acute decompensation and early death. We describe a 30-year-old woman who underwent successful BVR for pulmonary atresia with intact ventricular septum and demonstrate that where favorable anatomy exists with a failing Fontan, BVR should be considered.
Objective: Complex congenital heart disease presenting early in life may not be considered amenab... more Objective: Complex congenital heart disease presenting early in life may not be considered amenable for complete repair. These patients undergo palliative procedures most commonly utilizing the functioning ventricle to pump blood into the systemic and pulmonary circulations and staged rerouting of systemic venous blood to the pulmonary arteries. However, single ventricle physiology is associated with a number of well recognized complications. We describe successful palliation in 3 patients with complex congenital heart disease previously deemed irreparable and discuss its implications. Methods: Three patients with the following diagnosis – heterotaxy with complete atrioventricular canal defect, pulmonary atresia with intact ventricular septum, and pulmonary atresia with ventricular septal defect and major aortopulmonary connections (MAPCAs) – underwent a comprehensive assessment using two- and three-dimensional echocardiography, cardiac magnetic resonance imaging and cardiac cathete...
Seminars in thoracic and cardiovascular surgery. Pediatric cardiac surgery annual, 2000
The objective of this review was to analyze a surgical strategy for children with anomalous origi... more The objective of this review was to analyze a surgical strategy for children with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) where aortic implantation was successful without the use of extracorporeal membrane oxygenation (ECMO) or left ventricular assist device (LVAD). From 1989 through 1999, 16 consecutive children underwent aortic implantation for ALCAPA. Median age was 0.45 years. Surgical strategy included bicaval venous cannulation, LV vent, moderate systemic hypothermia (28 degrees C), antegrade cardioplegia with pulmonary artery (PA) occlusion, PA transection, aortic implantation with a large "button" of PA, PA reconstruction with pericardium, intraoperative transesophageal echocardiography, and inotropic support with dopamine, dobutamine, and milrinone. All patients survived. No patient was placed on ECMO or LVAD. Mean cardiopulmonary bypass (CPB) time was 152 +/- 41 minutes. Mean aortic cross-clamp time was 46 +/- 13 minutes. M...
Seminars in thoracic and cardiovascular surgery, 2004
Pneumonia with complicated parapneumonic effusion and empyema is increasing in incidence and cont... more Pneumonia with complicated parapneumonic effusion and empyema is increasing in incidence and continues to be a source of morbidity in children seen in our institution. Current diagnostic modalities include chest radiographs and CT scanning with ultrasound being helpful in some situations. Exact management of empyema remains controversial. Although open thoracotomy drainage is well accepted in children, video-assisted thoracoscopic surgery (VATS) drainage has become more prevalent in the current era. Over the last 4 years, we have treated 58 children with intrapleural placement of pigtail catheters and administration fibrinolytics consisting of tissue plasminogen activator (tPA). Successful drainage and resolution of 54 of the 58 effusions was achieved with percutaneous methods alone. There was no mortality or 30-day recurrence. Mean hospital stay was 9.1 days (range 5 to 21) and mean chest catheter removal was 6 days post placement (range 1.5 to 20). Of the four patients that failed...
The Journal of Thoracic and Cardiovascular Surgery, 1997
In the setting of acute pulmonary artery hypertension, techniques to reduce right ventricular ene... more In the setting of acute pulmonary artery hypertension, techniques to reduce right ventricular energy requirements may ameliorate cardiac failure and reduce morbidity and mortality. Inhaled nitric oxide, a selective pulmonary vasodilator, may be effective in the treatment of pulmonary artery hypertension, but its effects on cardiopulmonary interactions are poorly understood. We therefore developed a model of hypoxic pulmonary vasoconstriction that mimics the clinical syndrome of acute pulmonary hypertension. Inhaled nitric oxide was administered in concentrations of 20, 40, and 80 ppm. During hypoxic pulmonary vasoconstriction, the administration of nitric oxide resulted in a significant improvement in pulmonary vascular mechanics and a reduction in right ventricular afterload. These improvements were a result of selective vasodilation of small pulmonary vessels and more efficient blood flow through the pulmonary vascular bed (improved transpulmonary vascular efficiency). The right ventricular total power output diminished during the inhalation of nitric oxide, indicating a reduction in right ventricular energy requirements. The net result of nitric oxide administration was an increase in right ventricular efficiency. These data suggest that nitric oxide may be beneficial to the failing right ventricle by improving pulmonary vascular mechanics and right ventricular efficiency.
Journal of the American Society of Echocardiography, 1997
To use Albunex as a blood-flow tracer, the stability and consistency of microspheres under mixing... more To use Albunex as a blood-flow tracer, the stability and consistency of microspheres under mixing conditions must be known. This study examined the effects of mixing conditions and machine settings on the size and echogenicity of Albtmex solutions in vitro. Acoustic power, log compression, time-gain compensation, and transducer frequency were varied as Albunex solutions were imaged after mixing with magnetic stirring and pressurized. Higher acoustic power and lower transducer frequency decreased mean pixel intensity of AIbunex solution images over time. Intensity, size, and number ofAlbunex microspheres were not significantly different between stirring speeds. The echogenicity of the Albunex solutions decreased with pressurization, and the critical pressure necessary to reduce the intensity to half its initial value increased with the logarithm of concentration (r = 0.91; p < 0.001). The microsphere size decreased with pressurization and remained smaller after pressure release (3.66 -+ 2.13 versus 1.47 -+ 0.95 ~m; p < 0.01). These data indicate that acoustic power and transducer frequency may affect the physical properties of Albunex microspheres, decreasing mean videointensity. Pressure sensitivity of Albunex caused the decrease of videointensity and microsphere size. (J Am Soc Echocardiogr 1997;10:31-40.) Improvements in contrast agents and ultrasound machines have expanded the clinical use of contrast echocardiography to regional tissue perfusion imaging and transpulmonary contrast opacification of the left cardiac chambers) -s Newly developed contrast agents have shown promise in the visualization and quantitative assessment of blood flow, organ perfusion, and chamber function in real time. 2,4,6-s Although recent studies demonstrated that injection of a sonicated contrast agent into the aortic root or a coronary artery can delineate myocardial perfusion, 9H it is hoped that peripheral venous injection will be able to image myocardial perfusion and become a useful tool for diagnosis and after treatment of ischemic heart disease. ~,12 The potential of noninvasive myocardial perfusion imaging with contrast echocardiography continues to attract interest clinically and in research.
Background: This study was performed to evaluate and compare the early, intermediate, and long-te... more Background: This study was performed to evaluate and compare the early, intermediate, and long-term outcomes of the bidirectional Glenn procedure and Fontan procedure in patients who live at moderately high altitude. Methods: The outcome of each method of palliation for patients with a functionally single ventricle was retrospectively evaluated from a review of medical records. Results: The bidirectional Glenn procedure was performed in 177 patients from . Cardiovascular death or heart transplantation occurred in 8% of patients after the bidirectional Glenn procedure and 17% of patients after the Fontan procedure. Complications of systemic thromboembolic events, bleeding associated with anticoagulation therapy, protein losing enteropathy, and arrhythmias requiring implantation of a pacemaker, cardioversion, or radiofrequency ablation occurred in 7% of patients after the bidirectional Glenn procedure and 47% of patients after the Fontan procedure. Cardiovascular deaths and heart transplantation occurred less frequently when the Fontan procedure was performed in patients with a previous bidirectional Glenn procedure. However, the actuarial transplant-free survival and freedom from complications was not superior for a subgroup of patients who had a Fontan procedure after a bidirectional Glenn procedure in comparison to a subgroup of patients who had a bidirectional Glenn procedure alone. Conclusions: The bidirectional Glenn procedure can be used for long-term palliation of patients with a functionally single ventricle. Additional palliation with a Fontan procedure may increase the risk of stroke, protein losing enteropathy and arrhythmias without improving survival. D
Objectives: A Kommerell's diverticulum in patients with a right aortic arch may become aneurysmal... more Objectives: A Kommerell's diverticulum in patients with a right aortic arch may become aneurysmal and be an independent cause of tracheoesophageal compression, even after ligation and division of a left ligamentum. We review the indications for and results of Kommerell's diverticulum resection and left subclavian artery transfer in children with a right aortic arch who previously underwent vascular ring (ligamentum) division. Methods: From 1998 through 2001, eight children have been referred with recurrent respiratory symptoms (n ¼ 8) and/or recurrent dysphagia (n ¼ 4) after vascular ring division. Each child had a right aortic arch with a left ligamentum and had undergone division of the ligamentum elsewhere. All had a Kommerell's diverticulum that was not addressed at the initial operation. All patients had a repeat left thoracotomy with resection of the diverticulum. Five patients had division and reimplantation of the left subclavian artery into the left carotid artery to relieve the sling-like effect of the retroesophageal left subclavian artery on the right aortic arch. One other patient had primary Kommerell's diverticulum resection and transfer of the left subclavian artery to the left carotid artery. Results:
To test the hypothesis that in a swine model of acute respiratory distress syndrome (ARDS) with p... more To test the hypothesis that in a swine model of acute respiratory distress syndrome (ARDS) with permissive hypercapnia, inhaled nitric oxide would improve transpulmonary vascular mechanics and right ventricular workload while not changing intrinsic right ventricular contractility. Prospective, randomized, controlled laboratory trial. University research laboratory. Eleven swine (30 to 46 kg). The swine were anesthetized, intubated, and paralyzed. After median sternotomy, pressure transducers were placed in the right ventricle, pulmonary artery, and left atrium. An ultrasonic flow probe was placed around the pulmonary artery. Ultrasonic dimension transducers were sutured onto the heart at the base, apex, left ventricle (anterior, posterior, free wall), and right ventricle (free wall). An additional transducer was placed in the interventricular septum. A surfactant depletion model of ARDS was created by saline lung lavage. Nitric oxide was administered at 2, 4, and 6 parts per million (ppm), in a random order, under the condition of permissive hypercapnia (Paco2 55 to 75 torr [7.3 to 10.0 kPa]). We evaluated the pulmonary vascular and right ventricular effects of permissive hypercapnia, with and without inhaled nitric oxide, by measuring variables of transpulmonary vascular mechanics and right ventricular function. These variables included mean pulmonary arterial pressure, right ventricular total power, right ventricular stroke work, transpulmonary vascular efficiency, and right ventricular intrinsic contractility. Data were obtained after lung injury under the following conditions: a) normocapnia (Paco2 35 to 45 torr [4.7 to 6.0 kPa]) and nitric oxide at 0 ppm; b) hypercapnia and nitric oxide at 0 ppm; c) hypercapnia and nitric oxide at 2, 4, and 6 ppm; and d) repeat measurements with hypercapnia and nitric oxide at 0 ppm. In ARDS with permissive hypercapnia, inhaled nitric oxide therapy (2 to 6 ppm) improved transpulmonary vascular mechanics and right ventricular workload by lowering pulmonary arterial pressure (29.6 +/- 1.3 vs. 24.6 +/- 1.0 mm Hg, p = .0001), increasing transpulmonary vascular efficiency (13.9 +/- 0.5 vs. 16.1 +/- 0.7 L/W-min, p = .0001), decreasing right ventricular total power (142 +/- 9 vs. 115 +/- 9 mW, p = .001), and decreasing right ventricular stroke work (653 +/- 37 vs. 525 +/- 32 ergs x 10(3), p = .001). Inhaled nitric oxide did not change right ventricular contractility, as measured by preload-recruitable stroke work. Inhaled nitric oxide ameliorated any negative effects of hypoxic and hypercapnic pulmonary vasoconstriction. The beneficial effects of inhaled nitric oxide are related to alterations in right ventricular afterload and not intrinsic right ventricular contractility. The improved cardiopulmonary effects of inhaled nitric oxide with permissive hypercapnia potentially expand the use of nitric oxide in ARDS and other conditions in which this strategy is employed.
Seminars in thoracic and cardiovascular surgery. Pediatric cardiac surgery annual, 2000
The objective of this review was to analyze a surgical strategy for children with anomalous origi... more The objective of this review was to analyze a surgical strategy for children with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) where aortic implantation was successful without the use of extracorporeal membrane oxygenation (ECMO) or left ventricular assist device (LVAD). From 1989 through 1999, 16 consecutive children underwent aortic implantation for ALCAPA. Median age was 0.45 years. Surgical strategy included bicaval venous cannulation, LV vent, moderate systemic hypothermia (28 degrees C), antegrade cardioplegia with pulmonary artery (PA) occlusion, PA transection, aortic implantation with a large "button" of PA, PA reconstruction with pericardium, intraoperative transesophageal echocardiography, and inotropic support with dopamine, dobutamine, and milrinone. All patients survived. No patient was placed on ECMO or LVAD. Mean cardiopulmonary bypass (CPB) time was 152 +/- 41 minutes. Mean aortic cross-clamp time was 46 +/- 13 minutes. M...
Fontan palliation is used when biventricular repair (BVR) is not possible. Early outcomes are acc... more Fontan palliation is used when biventricular repair (BVR) is not possible. Early outcomes are acceptable; however, the long-term sequelae include protein-losing enteropathy, declining functional status, increased pulmonary vascular resistance, heart failure, and hepatic and renal dysfunction. These adverse events are characteristic of persistent venous hypertension and may be avoided if restoring biventricular circulation is possible. Arrhythmias are a common adverse event, particularly in patients with an atriopulmonary connection, which may lead to acute decompensation and early death. We describe a 30-year-old woman who underwent successful BVR for pulmonary atresia with intact ventricular septum and demonstrate that where favorable anatomy exists with a failing Fontan, BVR should be considered.
Objective: Complex congenital heart disease presenting early in life may not be considered amenab... more Objective: Complex congenital heart disease presenting early in life may not be considered amenable for complete repair. These patients undergo palliative procedures most commonly utilizing the functioning ventricle to pump blood into the systemic and pulmonary circulations and staged rerouting of systemic venous blood to the pulmonary arteries. However, single ventricle physiology is associated with a number of well recognized complications. We describe successful palliation in 3 patients with complex congenital heart disease previously deemed irreparable and discuss its implications. Methods: Three patients with the following diagnosis – heterotaxy with complete atrioventricular canal defect, pulmonary atresia with intact ventricular septum, and pulmonary atresia with ventricular septal defect and major aortopulmonary connections (MAPCAs) – underwent a comprehensive assessment using two- and three-dimensional echocardiography, cardiac magnetic resonance imaging and cardiac cathete...
Seminars in thoracic and cardiovascular surgery. Pediatric cardiac surgery annual, 2000
The objective of this review was to analyze a surgical strategy for children with anomalous origi... more The objective of this review was to analyze a surgical strategy for children with anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) where aortic implantation was successful without the use of extracorporeal membrane oxygenation (ECMO) or left ventricular assist device (LVAD). From 1989 through 1999, 16 consecutive children underwent aortic implantation for ALCAPA. Median age was 0.45 years. Surgical strategy included bicaval venous cannulation, LV vent, moderate systemic hypothermia (28 degrees C), antegrade cardioplegia with pulmonary artery (PA) occlusion, PA transection, aortic implantation with a large "button" of PA, PA reconstruction with pericardium, intraoperative transesophageal echocardiography, and inotropic support with dopamine, dobutamine, and milrinone. All patients survived. No patient was placed on ECMO or LVAD. Mean cardiopulmonary bypass (CPB) time was 152 +/- 41 minutes. Mean aortic cross-clamp time was 46 +/- 13 minutes. M...
Seminars in thoracic and cardiovascular surgery, 2004
Pneumonia with complicated parapneumonic effusion and empyema is increasing in incidence and cont... more Pneumonia with complicated parapneumonic effusion and empyema is increasing in incidence and continues to be a source of morbidity in children seen in our institution. Current diagnostic modalities include chest radiographs and CT scanning with ultrasound being helpful in some situations. Exact management of empyema remains controversial. Although open thoracotomy drainage is well accepted in children, video-assisted thoracoscopic surgery (VATS) drainage has become more prevalent in the current era. Over the last 4 years, we have treated 58 children with intrapleural placement of pigtail catheters and administration fibrinolytics consisting of tissue plasminogen activator (tPA). Successful drainage and resolution of 54 of the 58 effusions was achieved with percutaneous methods alone. There was no mortality or 30-day recurrence. Mean hospital stay was 9.1 days (range 5 to 21) and mean chest catheter removal was 6 days post placement (range 1.5 to 20). Of the four patients that failed...
The Journal of Thoracic and Cardiovascular Surgery, 1997
In the setting of acute pulmonary artery hypertension, techniques to reduce right ventricular ene... more In the setting of acute pulmonary artery hypertension, techniques to reduce right ventricular energy requirements may ameliorate cardiac failure and reduce morbidity and mortality. Inhaled nitric oxide, a selective pulmonary vasodilator, may be effective in the treatment of pulmonary artery hypertension, but its effects on cardiopulmonary interactions are poorly understood. We therefore developed a model of hypoxic pulmonary vasoconstriction that mimics the clinical syndrome of acute pulmonary hypertension. Inhaled nitric oxide was administered in concentrations of 20, 40, and 80 ppm. During hypoxic pulmonary vasoconstriction, the administration of nitric oxide resulted in a significant improvement in pulmonary vascular mechanics and a reduction in right ventricular afterload. These improvements were a result of selective vasodilation of small pulmonary vessels and more efficient blood flow through the pulmonary vascular bed (improved transpulmonary vascular efficiency). The right ventricular total power output diminished during the inhalation of nitric oxide, indicating a reduction in right ventricular energy requirements. The net result of nitric oxide administration was an increase in right ventricular efficiency. These data suggest that nitric oxide may be beneficial to the failing right ventricle by improving pulmonary vascular mechanics and right ventricular efficiency.
Journal of the American Society of Echocardiography, 1997
To use Albunex as a blood-flow tracer, the stability and consistency of microspheres under mixing... more To use Albunex as a blood-flow tracer, the stability and consistency of microspheres under mixing conditions must be known. This study examined the effects of mixing conditions and machine settings on the size and echogenicity of Albtmex solutions in vitro. Acoustic power, log compression, time-gain compensation, and transducer frequency were varied as Albunex solutions were imaged after mixing with magnetic stirring and pressurized. Higher acoustic power and lower transducer frequency decreased mean pixel intensity of AIbunex solution images over time. Intensity, size, and number ofAlbunex microspheres were not significantly different between stirring speeds. The echogenicity of the Albunex solutions decreased with pressurization, and the critical pressure necessary to reduce the intensity to half its initial value increased with the logarithm of concentration (r = 0.91; p < 0.001). The microsphere size decreased with pressurization and remained smaller after pressure release (3.66 -+ 2.13 versus 1.47 -+ 0.95 ~m; p < 0.01). These data indicate that acoustic power and transducer frequency may affect the physical properties of Albunex microspheres, decreasing mean videointensity. Pressure sensitivity of Albunex caused the decrease of videointensity and microsphere size. (J Am Soc Echocardiogr 1997;10:31-40.) Improvements in contrast agents and ultrasound machines have expanded the clinical use of contrast echocardiography to regional tissue perfusion imaging and transpulmonary contrast opacification of the left cardiac chambers) -s Newly developed contrast agents have shown promise in the visualization and quantitative assessment of blood flow, organ perfusion, and chamber function in real time. 2,4,6-s Although recent studies demonstrated that injection of a sonicated contrast agent into the aortic root or a coronary artery can delineate myocardial perfusion, 9H it is hoped that peripheral venous injection will be able to image myocardial perfusion and become a useful tool for diagnosis and after treatment of ischemic heart disease. ~,12 The potential of noninvasive myocardial perfusion imaging with contrast echocardiography continues to attract interest clinically and in research.
Background: This study was performed to evaluate and compare the early, intermediate, and long-te... more Background: This study was performed to evaluate and compare the early, intermediate, and long-term outcomes of the bidirectional Glenn procedure and Fontan procedure in patients who live at moderately high altitude. Methods: The outcome of each method of palliation for patients with a functionally single ventricle was retrospectively evaluated from a review of medical records. Results: The bidirectional Glenn procedure was performed in 177 patients from . Cardiovascular death or heart transplantation occurred in 8% of patients after the bidirectional Glenn procedure and 17% of patients after the Fontan procedure. Complications of systemic thromboembolic events, bleeding associated with anticoagulation therapy, protein losing enteropathy, and arrhythmias requiring implantation of a pacemaker, cardioversion, or radiofrequency ablation occurred in 7% of patients after the bidirectional Glenn procedure and 47% of patients after the Fontan procedure. Cardiovascular deaths and heart transplantation occurred less frequently when the Fontan procedure was performed in patients with a previous bidirectional Glenn procedure. However, the actuarial transplant-free survival and freedom from complications was not superior for a subgroup of patients who had a Fontan procedure after a bidirectional Glenn procedure in comparison to a subgroup of patients who had a bidirectional Glenn procedure alone. Conclusions: The bidirectional Glenn procedure can be used for long-term palliation of patients with a functionally single ventricle. Additional palliation with a Fontan procedure may increase the risk of stroke, protein losing enteropathy and arrhythmias without improving survival. D
Objectives: A Kommerell's diverticulum in patients with a right aortic arch may become aneurysmal... more Objectives: A Kommerell's diverticulum in patients with a right aortic arch may become aneurysmal and be an independent cause of tracheoesophageal compression, even after ligation and division of a left ligamentum. We review the indications for and results of Kommerell's diverticulum resection and left subclavian artery transfer in children with a right aortic arch who previously underwent vascular ring (ligamentum) division. Methods: From 1998 through 2001, eight children have been referred with recurrent respiratory symptoms (n ¼ 8) and/or recurrent dysphagia (n ¼ 4) after vascular ring division. Each child had a right aortic arch with a left ligamentum and had undergone division of the ligamentum elsewhere. All had a Kommerell's diverticulum that was not addressed at the initial operation. All patients had a repeat left thoracotomy with resection of the diverticulum. Five patients had division and reimplantation of the left subclavian artery into the left carotid artery to relieve the sling-like effect of the retroesophageal left subclavian artery on the right aortic arch. One other patient had primary Kommerell's diverticulum resection and transfer of the left subclavian artery to the left carotid artery. Results:
To test the hypothesis that in a swine model of acute respiratory distress syndrome (ARDS) with p... more To test the hypothesis that in a swine model of acute respiratory distress syndrome (ARDS) with permissive hypercapnia, inhaled nitric oxide would improve transpulmonary vascular mechanics and right ventricular workload while not changing intrinsic right ventricular contractility. Prospective, randomized, controlled laboratory trial. University research laboratory. Eleven swine (30 to 46 kg). The swine were anesthetized, intubated, and paralyzed. After median sternotomy, pressure transducers were placed in the right ventricle, pulmonary artery, and left atrium. An ultrasonic flow probe was placed around the pulmonary artery. Ultrasonic dimension transducers were sutured onto the heart at the base, apex, left ventricle (anterior, posterior, free wall), and right ventricle (free wall). An additional transducer was placed in the interventricular septum. A surfactant depletion model of ARDS was created by saline lung lavage. Nitric oxide was administered at 2, 4, and 6 parts per million (ppm), in a random order, under the condition of permissive hypercapnia (Paco2 55 to 75 torr [7.3 to 10.0 kPa]). We evaluated the pulmonary vascular and right ventricular effects of permissive hypercapnia, with and without inhaled nitric oxide, by measuring variables of transpulmonary vascular mechanics and right ventricular function. These variables included mean pulmonary arterial pressure, right ventricular total power, right ventricular stroke work, transpulmonary vascular efficiency, and right ventricular intrinsic contractility. Data were obtained after lung injury under the following conditions: a) normocapnia (Paco2 35 to 45 torr [4.7 to 6.0 kPa]) and nitric oxide at 0 ppm; b) hypercapnia and nitric oxide at 0 ppm; c) hypercapnia and nitric oxide at 2, 4, and 6 ppm; and d) repeat measurements with hypercapnia and nitric oxide at 0 ppm. In ARDS with permissive hypercapnia, inhaled nitric oxide therapy (2 to 6 ppm) improved transpulmonary vascular mechanics and right ventricular workload by lowering pulmonary arterial pressure (29.6 +/- 1.3 vs. 24.6 +/- 1.0 mm Hg, p = .0001), increasing transpulmonary vascular efficiency (13.9 +/- 0.5 vs. 16.1 +/- 0.7 L/W-min, p = .0001), decreasing right ventricular total power (142 +/- 9 vs. 115 +/- 9 mW, p = .001), and decreasing right ventricular stroke work (653 +/- 37 vs. 525 +/- 32 ergs x 10(3), p = .001). Inhaled nitric oxide did not change right ventricular contractility, as measured by preload-recruitable stroke work. Inhaled nitric oxide ameliorated any negative effects of hypoxic and hypercapnic pulmonary vasoconstriction. The beneficial effects of inhaled nitric oxide are related to alterations in right ventricular afterload and not intrinsic right ventricular contractility. The improved cardiopulmonary effects of inhaled nitric oxide with permissive hypercapnia potentially expand the use of nitric oxide in ARDS and other conditions in which this strategy is employed.
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Papers by Neal Hillman