Oxygen kinetics in experimental sepsis.

Systemic oxygen delivery (DO2) is normally four to five times higher than oxygen consumption (VO2), and VO2 is independent of DO2. If DO2 is decreased to less than twice VO2, a state of anaerobic metabolism and supply dependency occurs. Some authors have reported that this biphasic relationship is altered in the adult respiratory distress syndrome or sepsis to a condition of continuous supply dependency. If that were true, it would affect both our understanding and management of metabolism during sepsis. Therefore we measured VO2 and DO2 in a dog peritonitis model. DO2 was regulated with controlled pericardial tamponade. During sepsis VO2 increased 28% from a mean baseline of 5.6 to 7.3 cc O2/kg/min (p less than 0.005). As progressive cardiac tamponade was applied during sepsis, the DO2/VO2 ratio fell. When the DO2/VO2 ratio was greater than 2.4, VO2 remained independent of DO2. At DO2/VO2 ratios less than 2.4, VO2 was dependent on the level of DO2, and it diminished rapidly as DO2 decreased. Oxygen saturation in mixed venous blood (SvO2) consistently reflected the DO2/VO2 ratio in a fashion similar to that in normal dogs. A ratio of DO2/VO2 of 2.4 corresponded with an SvO2 of 42% +/- 12%, which was identified as a statistically significant critical SvO2 that marked onset of VO2 supply dependence. In this dog septic model, VO2 is independent of DO2 when DO2 is adequate. A state of continuous supply dependency does not exist. SvO2 reflects the status of the DO2/VO2 relationship in the septic state.

Laparoscopy for the impalpable testes: experience with 53 testes.

Impalpable testes constitute approximately 20% of most series of undescended testes. From January 1986 to March 1991, we performed laparoscopies on 53 patients with impalpable testes. Thirty-two of them were found to have normal vasa and vessels entering each internal ring on the side in question. Of these, 14 were found to have "vanishing testes" at exploration, 12 others underwent successful orchiopexy, and the remaining 6 had excisional biopsies of fibrotic testicular remnants. Five patients had no visible vessels and a sixth had a blind-ending vas and vessels adjacent to the internal ring; in these cases no further investigations were deemed necessary. Fifteen patients were found to have abdominal testes and underwent high testicular vessel ligation and division at the time of the laparoscopy; 14 of them have undergone staged orchiopexy 6 months after laparoscopy and one is scheduled for this procedure. A 3-month follow-up of those who had orchiopexy showed excellent results in 10 patients and poor results in 3, all of whom had small testes that were unimproved or worse following vessel ligation. Four boys were spared operations as a result of findings at laparoscopy. Early in the series there was one failed laparoscopy, but it was successfully completed later. the procedure, but it was successfully treated with antibiotics. There were no other complications. Laparoscopy is a safe procedure that allows accurate diagnosis and may prevent additional intervention in the treatment of the absent testes. It facilitates the locating of the impalpable testis and the planning and timing of subsequent orchiopexy. We believe that laparoscopy is the preferred procedure in the management of impalpable testes.

Massive ovarian edema in the pediatric patient: a rare solid tumor.

Solid ovarian masses in children are considered malignant unit proven otherwise. The authors report two cases of an unusual, benign, solid ovarian tumor found during ultrasound examination for evaluation of acute abdominal pain. Both patients were found to have a torsed nonviable ovary at the time of laparotomy. Patient 1 was a premenarcheal 10 year old who had undergone a lengthy evaluation for intermittent chronic abdominal pain. The ultrasound examination showed a 9- x 5-cm ovarian mass. Patient 2 was a virilized menarcheal 11 year old with a very large tumor (10 x 7 x 16 cm). The final pathology for both tumors was massive ovarian edema--a rare, stromal, virilizing tumor caused by chronic venous and lymphatic obstruction. Contralateral oophoropexy is a controversial treatment for the remaining ovary. A review of the literature regarding this uncommon tumor is provided.

Malignant risk in juvenile polyposis coli: increasing documentation in the pediatric age group.

The presence of juvenile polyps with resulting bleeding and abdominal pain has traditionally been considered a benign, self-limiting process which would resolve with age. The dictum that these polyps were usually solitary, were found predominantly in the rectosigmoid area, and were without malignant potential has been reconsidered in recent years with the increased use of colonoscopy. Several case reports in both adults and children have documented the presence of adenomatous changes in this syndrome. We report 3 cases of children, ages 3, 11, and 11 who were found to have adenomatous polyps in the midst of fields of juvenile polyps on evaluation for rectal bleeding. All three were treated definitively with endorectal pull-through. Two of these patients had atypia on histological evaluation, one of which was severe. We recommend a more aggressive approach to patients found to have multiple juvenile polyps on barium enema, including colonoscopic biopsies at several sites to determine the presence of adenomatous changes, with colectomy and endorectal pull-through should these be found.

Severe myocardial dysfunction during extracorporeal membrane oxygenation.

Of the 102 neonates with respiratory failure supported with extracorporeal membrane oxygenation (ECMO) at this institution between 1984 and 1987, 8 patients developed severe myocardial dysfunction that was noted shortly after onset of bypass. The neonates in the cardiac dysfunction group were more hypoxic (average PaO2 = 26 +/- 8 mm Hg v 41 +/- 19 mm Hg, P less than .01) in the immediate pre-ECMO period. Seventy-five percent were unstable hemodynamically (6 hypotensive, 3 bradycardic, 2 sustained cardiac arrest, 4 required epinephrine pressor support). On ECMO, 5 of the 8 neonates developed an ischemic cardiomyopathy that lasted for less than 24 hours and resolved without therapeutic intervention. In the other 3 cases, prolonged periods of dysfunction were noted and afterload reduction through administration of tolazoline or hydralazine was beneficial. These 8 patients serve to demonstrate the reversible nature of postischemic cardiac dysfunction in patients on ECMO and in the neonatal population in general.

Evaluation of the right atrial venous oxygen saturation as a physiologic monitor in a neonatal model.

Pulmonary artery (PA) mixed venous saturation (SvO2) has become a crucial monitor in the adult intensive care unit, but is not used in neonates because of the difficulty in PA catheterization. We evaluated the possibility of utilizing the right atrial venous oxygen saturation (RAvO2), which is easily accessed in the neonate, as a monitor of the effects of mechanical ventilation and intravascular volume in an animal model selected to be the size of the human neonate. A continuous RAvO2 monitoring catheter was placed into the right atrium of 16 normal rabbits (2.2 to 4.1 kg). Oxygen delivery was manipulated by alterations in peak inspiratory pressure (PIP) (n = 6), positive end-expiratory pressure (PEEP) (n = 6), or by progressive hypovolemia (n = 4). RAvO2 decreased with onset of mechanical ventilation alone from 69% +/- 6% to 61% +/- 5% (P < .01). As the PIP was increased from 12 to 21 cm H2O, the RAvO2 progressively decreased from 59% +/- 4% to 49% +/- 6% (P < .05). As the PEEP was increased from 3 to 9 cm H2O, the RAvO2 progressively decreased from 64% +/- 5% to 33% +/- 16% (P < .01). RAvO2 approached baseline after return to continuous positive airway pressure (CPAP) of 3 cm H2O. Progressive phlebotomy to a total of 10 mL/kg resulted in a decrease in RAvO2 from 70% +/- 6% to 27% +/- 5% (P < .001). Volume resuscitation resulted in an increase in RAvO2 to near baseline. Peripheral arterial oxygen saturation remained at a constant 100% throughout each protocol.(ABSTRACT TRUNCATED AT 250 WORDS)

Thoracoscopy in the management of pediatric empyema.

The surgical management of empyema consists of (1) aggressive therapy with thoracotomy and decortication or (2) conservative treatment with chest tube drainage and intravenous antibiotics. Recently, Kern and Rodgers introduced thoracoscopic debridement as an adjunct to the management of children with empyema, with promising results. Hence, the authors report their experience with thoracoscopy in the management of pediatric patients with empyema. In the last years, 10 children have undergone thoracoscopic debridement (TD) for empyema. The average age was 6.9 years (range, 2 to 16). Children underwent TD an average of 14 days (range, 8 to 16) after initial presentation and 4 days (range, 2 to 6) after admission to the authors' hospital. Indications for TD were persistent requirement of supplemental oxygen and failure of conservative medical management that consisted of antibiotics and tube thoracostomy. Three children had positive pleural fluid cultures for Streptococcus pneumoniae. In all cases, preoperative ultrasound or chest computed tomography examination showed dense pleural fluid with septation. During surgery, TD allowed for lung expansion and precise chest tube placement in all patients except one who required conversion to minithoracotomy and decortication for persistent encasement with a thick pleural peel. There were no postoperative complications related to the procedure. After TD, all children had prompt clinical improvement. The patients were weaned from supplemental oxygen by postoperative day 2, and following early chest tube removal, nine children were discharged home by postoperative day 7 (range, 3 to 10). One child required further hospitalization for underlying renal failure. In the authors' hands, TD was effective in producing prompt clinical improvement in children with empyema.(ABSTRACT TRUNCATED AT 250 WORDS)

Preferential use of venovenous extracorporeal membrane oxygenation for congenital diaphragmatic hernia.

Acute respiratory failure (ARF) secondary to congenital diaphragmatic hernia (CDH), unresponsive to maximal medical management, has traditionally been treated with venoarterial (VA) extracorporeal membrane oxygenation (ECMO). Venovenous (VV) ECMO offers several benefits over VA ECMO including preserved pulmonary blood flow, preservation of the carotid artery, and pulsatile flow. However, use of the VV modality has not been widespread because of concerns of the cardiac instability during bypass, and because only one double-lumen (DL) catheter size is available in the United States. The authors hypothesize that VV ECMO is a safe and effective treatment for CDH, symptomatic at birth, and report a single institution experience of preferential VV use for CDH. Over an 18-month period, 14 patients with CDH were placed on ECMO after maximal medical management failed, including high-frequency ventilation and nitric oxide in some cases. Ability to place the 14 Fr DL catheter was the sole criteria for VA or VV selection. Nine patients were successfully placed on VV and 5 on VA; no VV patient required conversion to VA. The two groups of patients were similar with respect to degree of illness, birth weight, EGA, time on and age at start of ECMO. Overall survival for this series was 64%: 66% in the VV group and 60% in the VA group. Two patients in the VV group were found to have congenital heart disease incompatible with life, were withdrawn from therapy and allowed to die, and are listed as treatment failures. The authors conclude that CDH patients receive adequate oxygenation and show hemodynamic stability on VV ECMO.(ABSTRACT TRUNCATED AT 250 WORDS)

Life-threatening intrathoracic complications during treatment with extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) has been successful (greater than 80% survival) in 35 centers in greater than 900 newborns with severe respiratory failure having an estimated mortality of greater than 80% on conventional management. During the last 3 years we have treated 79 newborns with 74 survivors (94%). Their diagnoses included meconium aspiration, persistent fetal circulation, respiratory distress syndrome, congenital diaphragmatic hernia, and sepsis. Seven patients (9%) had life-threatening intrathoracic complications requiring emergent intervention while on ECMO: tension hemothorax (3), tension pneumothorax (2), and pericardial tamponade (2). Pericardial tamponade and tension hemothorax and pneumothorax show a similar pathophysiology of increasing intrapericardial pressure and decreasing venous return. Perfusion is initially maintained by the nonpulsatile flow of the ECMO circuit before further decrease in venous return results in decreasing ECMO flow and progressive hemodynamic deterioration. Each of the seven patients demonstrated a clinical triad that includes increasing PaO2 and decreasing peripheral perfusion (as evidenced by decreasing pulse pressure and decreasing SvO2) followed by decreasing ECMO flow with progressive deterioration. The diagnoses were confirmed by transillumination, chest x-ray, or cardiac echocardiogram. Initial emergent placement of a percutaneous drainage catheter was temporizing in all seven cases. However, four patients required emergent thoracotomy for definitive treatment while still on ECMO. All seven patients were weaned from ECMO and are short-term survivors (6 months to 3.5 years). As use of ECMO for newborn severe respiratory failure increases, responsible physicians must be familiar with life-threatening intrathoracic complications and appropriate treatment strategies.

Prediction of mortality in neonates with congenital diaphragmatic hernia treated with extracorporeal membrane oxygenation.

OBJECTIVE: To determine if data collected by the Extracorporeal Life Support Organization Registry could be used to identify neonates with congenital diaphragmatic hernia who had a > 90% mortality rate, despite the use of extracorporeal membrane oxygenation (ECMO) support. DESIGN: We retrospectively reviewed data reported to the Extracorporeal Life Support Organization Registry on neonates with congenital diaphragmatic hernia. PATIENTS: Data regarding 1,089 neonates with congenital diaphragmatic hernia reported to the Extracorporeal Life Support Organization Registry between 1980 and 1992 formed the basis of this study. All of the neonates studied had been treated with ECMO. This patient population includes neonates with right- and left-sided diaphragmatic hernia. This registry does not include neonates with congenital diaphragmatic hernia who were not treated with ECMO. MEASUREMENTS AND MAIN RESULTS: Of 1,089 neonates with congenital diaphragmatic hernia, 679 (62%) survived. There were no differences between the two groups in gender or in the year they were treated. Survival rate did not significantly increase over the years between 1980 and 1992. When compared with survivors, nonsurvivors were more immature (38 +/- 2 vs. 39 +/- 2 wks; p = .01), had lower birth weights (3.0 +/- 0.5 vs. 3.21 +/- 0.53 kg; p = .001), were more often prenatally diagnosed (42% vs. 32%; p = .03), were cannulated at a younger age (31 +/- 54 vs. 40 +/- 50 hrs; p = .01), and had more severe respiratory compromise (higher peak pressures and PaCO2, lower PaO2 values). Multivariate analysis showed that arterial pH and PaO2 just before ECMO, and birth weight, had the highest discriminant coefficients. By using these variables in a discriminant function (D[fx] = 0.68 x pH + 0.62 x birth weight + 0.29 x PaO2; using standardized coefficients and variables), we could identify neonates who died with a sensitivity of 62%, a specificity of 63%, a positive-predictive value of 50%, and a negative-predictive value of 74%. No single variable or combination of variables yielded better results. CONCLUSIONS: Although a number of factors identify neonates with diaphragmatic hernia as being at higher risk of dying despite ECMO support, data currently collected by the neonatal Extracorporeal Life Support Organization Registry do not allow clinicians to effectively discriminate nonsurvivors from survivors.

Efficacy of venovenous extracorporeal membrane oxygenation for neonates with respiratory and circulatory compromise.

We report a 12-month experience at Egleston Children's Hospital in Atlanta, Ga., with a protocol under which venovenous extracorporeal membrane oxygenation (ECMO) was used instead of venoarterial ECMO. Fifty-five newborn infants were referred for ECMO, four of whom had disqualifying conditions (all four died). Thirty-one infants were supported without recourse to ECMO, one of whom died. Of the 20 remaining patients, three were placed on a venoarterial ECMO regimen because of our early uncertainty about the efficacy of venovenous ECMO or because of technical constraints. All other patients (n = 17), including three with congenital diaphragmatic hernia, were supported with venovenous perfusion. No patient begun on a venovenous ECMO regimen required conversion to venoarterial bypass. Before ECMO, venovenous patients required an average dopamine dose of 16 micrograms/kg per minute and an average dobutamine dose of 6 micrograms/kg per minute. Of 15 patients studied before ECMO, three had significantly impaired contractility, and all had evidence of pulmonary hypertension on an echocardiogram. Mean blood pressure did not change while heart rate fell from 172 to 146 beats/min during the first 2 hours of ECMO and vasoactive drug doses were reduced. Of the 17 venovenous ECMO patients, 15 (88%) survived. We conclude that neonatal patients with severe hypoxia and substantial circulatory compromise can be effectively supported by venovenous ECMO in most cases.

Evaluation of Duraflo II heparin coating in prolonged extracorporeal membrane oxygenation.

Adult sized extracorporeal membrane oxygenation circuits were coated with Duraflo II chemical heparin bonding by Baxter-Bentley Laboratories. Five sheep were maintained on venovenous extracorporeal circulation for four days with no systemic anticoagulation. There was no bleeding, no major thrombosis in the circuits, and no significant emboli after 4 days of extracorporeal circulation without anti-coagulation.