Fluid resuscitation improves intestinal blood flow and reduces the mucosal damage associated with strangulation obstruction in pigs

BACKGROUND: Strangulation obstruction of the small bowel is associated with local and systemic circulatory changes, local loss of fluid, and damage of the strangulated bowel segment. We wanted to examine to which extent these changes can be prevented by intravenous fluid administration. MATERIALS AND METHODS: In anesthetized pigs, strangulation obstruction was induced by increasing the pressure in a baby pressure gasket placed around a loop of ileum until venous pressure in the loop reached 50 mm Hg. During the strangulation period (180 min), a group of eight animals (Fluid(min) group) received 10 ml. kg(-1). hour(-1) Ringer acetate solution intravenously, whereas another eight animals (Fluid(max) group) received 55 ml. kg(-1). hour(-1) Ringer acetate solution intravenously. Blood flow to the strangulated bowel was measured by transit time flowmetry and colored microspheres. After completed experiments, whole wall samples of the strangulated loop were selected for microscopy. RESULTS: In the Fluid(min) group, the heart rate increased, the arterial pressure decreased markedly, and the urine output decreased toward zero. In the Fluid(max) group, the heart rate and arterial pressure remained fairly constant and the urine output increased. Blood flow to the strangulated bowel decreased in both groups, but significantly more in the Fluid(min) group. The intestinal blood flow was highly dependent on the arterial blood pressure. The strangulated mucosa showed markedly more damage in the Fluid(min) group than the Fluid(max) group. The degree of mucosal damage correlated linearly with the mucosal blood flow. CONCLUSION: The administration of large amounts of fluid to animals with strangulation obstruction normalized the arterial pressure and improved the intestinal blood flow thus minimizing damage to the intestinal mucosa.     

The causes and value of hyperphosphatemia in experimental strangulation obstruction

In model experiments with mongrel dogs, intestinal strangulation obstruction was induced by occluding the superior mesenteric veins, and a rise in the inorganic phosphate value of the blood was observed. The high inorganic phosphate values of the fluid exuding from the strangulated bowel suggest that intestinal factors associated with the strangulated bowel may be partly responsible for this elevated phosphatemia. However, hyperphosphatemia was also found in a model experiment in which the route through which the fluid was absorbed into the blood from the peritoneal cavity was interrupted by keeping the strangulated bowel in an intestinal bag. After this, in the model experiments in which a systemic blood pressure depression curve with a percentage reduction similar to that of the decreasing arterial blood pressure resulting from strangulation was produced (by exsanguination, and even by exsanguination with adequate perfusion of the gut), plasma inorganic phosphate values also increased. Therefore it is undeniable that systemic factors other than the above-mentioned local factors are related to the rise in plasma inorganic phosphate values in experimental strangulation obstruction. Because it is not possible to assert that phosphatemia is specific to intestinal strangulation, the importance of a rise in inorganic phosphate values in the early diagnosis of intestinal strangulation cannot be considered very great.     

Role of endothelin in the circulatory changes associated with small bowel strangulation obstruction in pigs: effects of the endothelin receptor antagonist bosentan

BACKGROUND: We have previously shown that experimental strangulation obstruction leads to increased release and concentration of endothelin-1 (ET-1) in venous blood from the strangulated bowel loop. The present study focuses on the microcirculatory effects of the released ET-1 in strangulation obstruction. METHODS: In anesthetized pigs strangulation obstruction was induced by increasing pressure in a baby pressure gasket placed around a loop of ileum until venous pressure reached 45 mm Hg. The pigs were randomly allocated into two groups. The nonselective ET(A)/ET(B) antagonist bosentan was administered intravenously (5 mg kg(-1)) to eight pigs (bosentan group) 30 min before strangulation, which was maintained for 90 min. Another eight pigs were treated in same manner except for the bosentan injection (control group). RESULTS: The concentration of ET in arterial and intestinal venous blood increased markedly after intravenous administration of bosentan. Intravenous infusion of bosentan was followed by a reduction in systemic arterial blood pressure. Bosentan reduced vascular resistance and increased blood flow in the normal intestinal mucosa. It also reduced muscularis blood flow in the beginning of the experiment. In strangulated small bowel bosentan inhibited the increase in vascular resistance usually caused by strangulation obstruction. Muscularis blood flow in strangulated small bowel was not affected by bosentan. CONCLUSION: Endothelin is involved in the normal regulation of arterial blood pressure. The increase in vascular resistance associated with strangulation obstruction is caused mainly by locally released endothelin.     

Congenital complete absence of left pericardium Report of two cases

Two cases of congenital complete absence of the left pericardium are presented. One, in a youth aged 17 years, had an associated patent ductus arteriosus; the other occurred in a woman aged 65 years with carcinoma of the lower third of the oesophagus. In both, the pericardial lesion was discovered as an incidental finding—at thoracotomy. The anatomical and radiographic features are described. Complete absence of the left side of the pericardium needs no surgical treatment and is compatible with normal life expectancy. On the other hand, because of the dangers of herniation of the heart with strangulation, partial defects should be closed, using either mediastinal pleura or fabric such as Dacron or Teflon.     

Rupture of the diaphragm of late manifestation

Twenty one cases of delayed diagnosis of ruptured diaphragm caused by closed trauma are reported: 14 on the left side and 7 on the right side. The clinical signs and the modes of presentation are non-specific. Although the history of thoraco-abdominal trauma and the chest x-ray are sufficient to establish the diagnosis of rupture of the left hemidiaphragm, they can only suggest the diagnosis in cases of righ-sided rupture. The mechanism of rupture is more often due to sudden reflex contraction of the diaphragm against a closed glottis than to excessive abdominal pressure caused by the trauma. Diaphragmatic rupture due to closed trauma causes large tears exposing the patient to a low risk of strangulation of intestinal structures in contrast with ruptures due to a penetrating injury, which causes small tears. The diaphragmatic domes must be systematically explored during laparotomy or thoracotomy performed for thoraco-abdominal trauma.     

The cardiac pendulum: blunt rupture of the pericardium with strangulation of the heart

BACKGROUND: Blunt injury of the pericardium with strangulation of the heart is a rare clinical injury. METHODS: We conducted a review of clinical records and performed prospective collection of forensic data from a large urban medical examiner's office. RESULTS: Ten cases of blunt injury to the pericardium were identified. All were secondary to blunt trauma. Nine of the 10 cases had associated chest wall injuries and 5 of the 10 cases had cardiac strangulation. CONCLUSION: Pericardial lacerations are common findings at autopsy. Clinically, those that survive to the hospital have a confusing presentation. They are often diagnosed during emergent thoracotomy for hemodynamic instability. Hemodynamic deterioration associated with change in patient position may be a clue to cardiac strangulation.     

Traumatic injuries of the diaphragm. Diaphragmatic hernia

Trauma to the diaphragm may be direct or indirect, and herniation may be obscured by concomitant injuries and may remain occult for many years.The early physical signs and symptoms are meager before the abdominal organs have penetrated deeply into the thorax. The progress of injury can be divided into three phases: (1) initial, (2) latent, and (3) obstructive.Most traumatic hernias occur on the left side because of the diminished buffering force on the undersurface of the left hemidiaphragm. Roentgenograms are most often misinterpreted as indicating eventration of the diaphragm, gastric dilatation, or lesions in the lower lung fields or pleura. A dilated stomach in the left pleural cavity may simulate a pneumothorax. Diaphragmatic injury should always be considered in conjunction with trauma to the liver, kidneys, and spleen. Intestinal obstruction may occur with few significant abdominal findings, when most of the involved viscera are in the thorax. The thoracic approach to surgery provides excellent exposure. The herniated viscera which may be adherent to the lung or pericardium can be released conveniently, there is easy access to the diaphragmatic rent, and lacerations near the heart and esophagus can be repaired without fear of further injury. Extensions or separate abdominal incisions may be necessary to manage concomitant injuries, especially in the initial phase.Wounds of the diaphragm are not likely to heal spontaneously; often the omentum or other viscera plug the laceration, thereby preventing acute herniation. However, this same mechanism separates the muscle edges, preventing their union. Traumatic ruptures of the diaphragm are twelve times more common on the left side due to the protection afforded by the liver. Diaphragmatic tears are most common in the dome and the posterior half which are the areas of embryonic weakness. When strangulation of bowel occurs in the thorax, approximately 90 per cent of the cases are due to traumatic hernia of the diaphragm, and when strangulation occurs, the mortality varies from 25 to 66 per cent.     

Sigmoid colon strangulation caused by bilateral fallopian tubes: A case report

IntroductionThere are no reports regarding sigmoid colon strangulation caused by bilateral fallopian tubes, which is a rare type of large bowel obstruction. Herein, we report a case of successful laparoscopic treatment of sigmoid colon strangulation.Presentation of caseA 54-year-old woman presented to our hospital with intermittent abdominal pain. Her medical history was significant for endometriosis; however, there was no surgical history. The physical examination revealed tenderness over the lower abdomen. CT scan shows closed loop obstruction of sigmoid colon. Exploratory laparoscopy was performed, and a sigmoid colon strangulated by bilateral fallopian tubes was detected. The adhesions consisting of bilateral fallopian tubes were dissected laparoscopically. The patient's postoperative course was uneventful, with no complications.DiscussionThe most common cause of large bowel obstruction (LBO) is colorectal cancer, including volvulus and diverticulitis. In this case, the adhesion of both the right and left fallopian tubes caused LBO, and it is conceivable that the etiology involved is endometriosis.Few cases have reported bowel obstruction associated with a fallopian tube, and the laparoscopic approach is very rare. In our case, we immediately performed laparoscopic exploration before colon strangulation led to necrosis or perforation. Therefore, we succeeded in releasing the strangulation laparoscopically.ConclusionWe report a case of sigmoid colon strangulation that was treated laparoscopically. This approach can be the treatment of choice for sigmoid colon strangulation.     

Determinants of maximal right ventricular function: role of septal shift.

BACKGROUND: Right heart failure can occur after orthotopic heart transplantation and can complicate implantation of left ventricular assist devices. The functional codeterminants of right ventricular function are not fully understood. We investigated the effects of left ventricular preload and afterload, systemic pressure, and the contribution of the interventricular septum to right ventricular function. METHODS AND RESULTS: In vivo studies were conducted in 12 dogs by using a highly defined, isovolumic right heart preparation. At any given arterial pressure, maximal right ventricular developed pressure was not influenced by left heart output; however, right ventricular volumes at which peak right ventricular developed pressure occurred differed significantly between the volume-loaded versus the unloaded left ventricle (P <.05). A correlation was found between peak right ventricular developed pressure and mean arterial pressure. The shift of the interventricular septum toward the left ventricle is delayed under the influence of left ventricular volume load, but the maximal interventricular septal deformation does not differ at maximal right ventricular developed pressure. There was a substantial and significant decrease in peak right ventricular developed pressure when the interventricular septum was inactivated (P <.05). CONCLUSIONS: Right ventricular function has multiple determinants, including the right ventricular free wall, the left ventricle, and the interventricular septum. Changes in right ventricular performance caused by alterations in left ventricular volume load and mean arterial pressure are mediated partially through the interventricular septum, as well as through perfusion of the right ventricular free wall; inactivation of the interventricular septum leads to a significant decrease in right ventricular function. Maintaining left ventricular developed pressure and hence the contribution of the interventricular septum to right ventricular function may be important in the management of right ventricular failure.     

Experimental heterotopic heart transplantation without cardiopulmonary bypass: auxiliary support for the recipient heart.

BACKGROUND: Auxiliary cardiac support using heterotopic heart transplant is of considerable interest, but the outcome is not known. To investigate technical feasibility and the possibility of using auxiliary support from heterotopic heart transplantation without cardiopulmonary bypass, we evaluated hemodynamics including the pressure-volume relationship in experimental animals. METHODS: In heterotopic heart transplantation, we tailored the donor heart by removing the pulmonary and tricuspid valves, and by wide removal of the inter-atrial septum. Next, we anastomosed the descending aorta and left atrium of the donor heart to the descending aorta and left atrium of the recipient, without using cardiopulmonary bypass. Consequently, declamping the recipient's descending aorta allowed the donor heart to fill with blood and to start beating. We performed hemodynamic assessments including the effects of adrenergic stimulation. We measured the pressure and volume relationship of the recipient heart by closing and opening inflow of the donor left atrium to change the pre-load of the donor left ventricle. RESULTS: The donor left ventricle produced a systolic blood pressure that was augmented by the recipient blood pressure and responded to adrenergic stimulation. When inflow of the donor left atrium was opened, the pressure-volume loop of the recipient heart shifted to the left and pressure-volume area decreased. Simultaneously, the mechanical efficiency and E(max) (the slope of the end-systolic pressure-volume relationship) of the recipient heart increased when inflow of the donor left atrium was opened. CONCLUSIONS: This transplant model, without cardiopulmonary bypass, is feasible and can be applied to transplant investigations as a working heart model on the basis of the response of adrenergic stimulation. The increased pre-load of the donor left atrium from the recipient left atrium resulted in a recipient leftward shift of the pressure-volume relationship, suggesting that this transplant model with adequate pre-load acts as auxiliary assistance in the recipient intrathoracic cavity.     

Development of a Direct Mechanical Left Ventricular Assist Device for Left Ventricular Failure

Abstract: We have developed a direct mechanical left ventricular assist device (DMLVAD) for severe left ventricular failure. The DMLVAD was attached to the left ventricle and compressed the heart by a pneumatic driving unit. In a mock circulation model with an extracted non-beating heart, a cardiac output (CO) of 1.93 L/min was obtained at a driving pressure of 200 mm Hg. In a canine left ventricular failure model induced by injection of sodium hydroxide into the myocardium, the systolic arterial pressure, systolic left ventricular pressure, maximum LV dP/dt, peak flow, and CO increased by 21, 24, 58, 144, and 37%, respectively. The mean left atrial pressure also decreased by 15% when the DMLVAD was driven. These effects were most prominent when the mean left atrial pressure was over 15 mm Hg, and the driving pressure was over 100 mm Hg. Compression at late systole was more effective in obtaining greater CO. We suggest that the DMLVAD could be an optional circulatory assist device for patients with left ventricular failure awaiting heart transplantation.     

Traumatic lumbar visceral herniation in a young woman

INTRODUCTIONLumbar herniation is uncommon, with traumatic etiology being rare. Traumatic lumbar hernias are usually caused by seatbelt injury in motor vehicle accidents. It is exceedingly uncommon to see lumbar hernias in an unrestrained passenger of a motor vehicle accident.PRESENTATION OF CASEWe present a case of a traumatic inferior lumbar hernia in a young woman who was an unrestrained driver of a vehicle involved in a high-speed collision, with multiple rollover and ejection. CT scans of the abdomen and pelvis suggested soft tissue injury involving muscles in the left lower posterior flank with traumatic herniation of the colon and small bowel. Emergent midline abdominal laparotomy confirmed herniation in the left lower quadrant. After abdominal closure, in the prone position, an extensive laceration over the left flank also confirmed herniation. Due to its dirty nature, the wound was irrigated, lavaged and covered with wound vacuum-assisted closure placement. The decision was made in favor of delayed elective hernia repair.DISCUSSIONLumbar hernias are usually caused by sudden force to the abdomen, leading to increased intra-abdominal pressure. This pressure combined with areas of weakness in the superior and/or inferior triangle lead to herniation. Uncommonly, the contents of lumbar hernias can strangulate or incarcerate leading to bowel obstruction. This can often be prevented by detection with CT and laparotomy.CONCLUSIONLumbar herniation of traumatic etiology is rare. Early detection with CT and/or exploratory laparotomy is important to avoid increases in size of the defect and bowel strangulation and incarceration.     

Abdominal heart transplantation: description of a new allograft extrathoracic pump

This study describes a new kind of abdominal heart transplantation for left ventricular assistance carried out in a series of 12 experiments in pigs weighing 15-25 kg. This was achieved making three connections between the donor's left atrium, aorta and pulmonary artery with the recipient's aorta, still aorta and inferior vena cava, respectively. The hemodynamic data were satisfactory, the best survival rate with a transplanted working heart was 1 month. The low output of the recipient's left ventricle was obtained by ligation of the left anterior descending (LAD) coronary artery. In all animals, the highest peak of the pressure of the transplanted left ventricle was at least 20 mm Hg higher (ranging from 20 to 60 mm Hg) than the pressure in the recipient's left ventricle, and corresponded with the peak of the systemic arterial pressure. The cardiac output of the transplanted hearts showed a good hemodynamic response with support of the circulation after ligation of the LAD coronary artery in the recipient's heart.     

Exposure of circumflex branches in the tilted, beating porcine heart: echocardiographic evidence of right ventricular deformation and the effect of right or left heart bypass.

OBJECTIVE: In off-pump coronary surgery, exposure of posterior vessels via sternotomy causes deterioration of cardiac function. Changes in ventricular geometry, valve competence, and hemodynamics after retraction of the beating heart were studied. Subsequently, the modifying effect of right or left heart bypass was investigated. METHODS: In six 80-kg pigs, an ultrasound probe was attached to the backside of the left ventricle and the heart was fully retracted with a suction tissue stabilizer. Five pigs underwent additional pump support. RESULTS: During retraction, the right ventricle was squeezed between the pericardium and interventricular septum, thereby decreasing its diastolic cross-sectional area by 62% +/- 6% (P <.001) while, concomitantly, right ventricular end-diastolic pressure increased to 165% +/- 19% (P =.004) of basal values. Stroke volume and mean arterial pressure decreased by 29% +/- 6% and 23% +/- 8% (P =.007 and P =.02, respectively). Left ventricular shape became somewhat elliptic without changes in preload pressure, and its diastolic cross-sectional area decreased by 20% +/- 3% (P =.001). All valves were competent. Right heart bypass restored left ventricular cross-sectional area, stroke volume, and mean arterial pressure. In contrast, left heart bypass increased blood pressure only marginally. CONCLUSIONS: Ninety-degree anterior displacement of the beating porcine heart caused primarily right ventricular dysfunction as a result of mechanical interference with diastolic expansion without concurring valvular incompetence. Right heart bypass normalized stroke volume and mean arterial pressure by increasing left ventricular preload; in contrast, left heart bypass failed to restore systemic circulation.     

Transverse colon diverticulitis simulating inguinal hernia strangulation: a first report

BACKGROUND: Strangulation is the most serious complication of inguinal hernia. Diverticulitis, a common condition, is usually localized in the left colon. The association of complicated inguinal hernia and diverticulitis is rare. METHODS: We report the case of a 73-year-old male patient who presented with a suspicion of strangulated inguinal hernia. RESULTS: CT and operative findings showed transverse colon diverticulitis lodged in an incarcerated inguinal hernia without signs of strangulation. Surgical hernia repair was undertaken while the treatment of diverticulitis was conservative. Follow-up was uneventful. CONCLUSION: This is a first report of documented transverse colon diverticulitis simulating inguinal hernia strangulation.     

Evaluation of cardiac function during left ventricular assist by a centrifugal blood pump

In this study, the effects on varying cardiac function during a left ventricular (LV) bypass from the apex to the descending aorta using a centrifugal blood pump were evaluated by analyzing the left ventricular pressure and the motor current of the centrifugal pump in a mock circulatory loop. Failing heart models (preload 15 mm Hg, afterload 40 mm Hg) and normal heart models (preload 5 mm Hg, afterload 100 mm Hg) were simulated by adjusting the contractility of the latex rubber left ventricle. In Study 1, the bypass flow rate, left ventricular pressure, aortic pressure, and motor current levels were measured in each model as the centrifugal pump rpm were increased from 1,000 to 1,500 to 2,000. In Study 2, the pump rpm were fixed at 1,300, 1,500, and 1,700, and at each rpm, the left ventricular peak pressure was increased from 40 to 140 mm Hg by steps of 20 mm Hg. The same measurements as in Study 1 were performed. In Study 1, the bypass flow rate and mean aortic pressure both increased with the increase in pump rpm while the mean left ventricular pressure decreased. In Study 2, a fairly good correlation between the left ventricular pressure and the motor current of the centrifugal pump was obtained. These results suggest that cardiac function as indicated by left ventricular pressure may be estimated from a motor current analysis of the centrifugal blood pump during left heart bypass.     

Analysis of hemodynamic changes during beating heart surgical procedures

BACKGROUND: Coronary artery bypass grafting on the beating heart causes significant hemodynamic compromise during displacement of the heart. The precise mechanisms causing altered hemodynamics have not been clearly understood. The purpose of this study was to define the hemodynamic changes caused by displacing the heart in patients undergoing beating heart surgical procedures. METHODS: Forty-four patients (35 men, 9 women; mean age, 64.5 +/- 9.6 years) underwent off-pump coronary artery bypass grafting. The hemodynamic variables were collected before and after positioning the heart for anastomosis of the left anterior descending, circumflex, and posterior descending coronary arteries. RESULTS: There was a significant increase in right ventricular end-diastolic pressure during positioning for all vessels, and in left ventricular end-diastolic pressure during positioning for the left anterior descending and circumflex coronary arteries. Positioning for the circumflex artery showed the largest increase of left and right ventricular end-diastolic pressure, resulting in the greatest hemodynamic compromise. CONCLUSIONS: In the clinical setting of diseased human hearts, there is a biventricular contribution to altered hemodynamics. The increase of right ventricular end-diastolic pressure in all positions suggests that the major cause of hemodynamic changes is disturbed diastolic filling of the right ventricle, especially by direct ventricular compression.     

Left heart decompression by closed gravity drainage

Decompression of the left ventricle by closed gravity drainage into the venous return reservoir was found to be an especially useful adjunct in coronary artery surgery. The preferred technique of transatrial cannulation of the left ventricle affords efficient left heart decompression during heart-lung bypass and is used for direct measurement of left heart pressure and, when indicated, for selective left heart bypass.     

Effects of left heart bypass on right ventricular performance. Evaluation of the right ventricular end-systolic and end-diastolic pressure-volume relation in the in situ normal canine heart

Although left heart bypass has gained popularity as a powerful technique to assist the severely failed left heart, apparent right heart failure has often developed during the bypass procedure. We investigated whether the coexisting right heart failure is attributable to the left heart bypass in 16 open-chest dogs. We evaluated the effects of left heart bypass on the right ventricular systolic properties by the slope of the end-systolic pressure-volume relation and its effects on the diastolic properties by chamber compliance. Overall right ventricular performance was assessed by the end-diastolic pressure versus cardiac output relationship. The left heart bypass decreased the slope slightly when the assisted flow ratio exceeded 75% (-14% +/- 8% at the assisted flow ratio of 100%, p less than 0.02) and thus had a deleterious influence on right ventricular performance. The left heart bypass, on the other hand, had a counteracting beneficial influence on right ventricular performance through the increase in chamber compliance (38% +/- 5%, p less than 0.01) and the decrease in pulmonary arterial input resistance (-15% +/- 12%, p less than 0.01). The net effect of the left heart bypass was the increase in cardiac output (20% +/- 2%, p less than 0.05) for any given right ventricular end-diastolic pressure. We conclude that in normal hearts the left heart bypass augments right ventricular performance. We ascribe these beneficial effects to diastolic ventricular interdependence and afterload unloading.     

Cardiovascular effects of flunitrazepam (rohypnol, RO-5-4200) (author's transl)]

We reported on the haemodynamic effects of 0.03 mg/kg flunitrazepam during surgical procedures in neuroleptanalgesia in 39 patients with congenital or acquired heart diseases, functional class II-IV. The benzodiazepine derivative did not cause any relevant effect on the inotropic state of the myocardium. There were only minor changes in cardiac index, stroke index, right and left atrial pressure. Changes in arterial pressure and left ventricular pressure during and immediately after surgical procedures, and in arterial perfusion pressure during extracorporeal circulation, as well as an only short lasting increase in heart rate were demonstrative a peripheral vasodilator effect. The decrease in ventricular work and myocardial oxygen consumption are of value in patients with coronary heart disease, especially immediately after surgical procedures. Flunitrazepam is considered an additional drug during neuroleptanalgesia, when hypertension is causing some problems.