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Biomedical subjects

L N Cook

Publications and source records attributed to L N Cook.

At least 19 recordsLinked to original sources
PubMed2001

Thyroid function in neonates with severe respiratory failure on extracorporeal membrane oxygenation.

The object was to study thyroid function in neonates with severe respiratory failure on extracorporeal membrane oxygenation (ECMO) and determine whether abnormal thyroid function correlates with prognosis. Total and free thyroxine (T4, FT4), total and free triiodothyronine (T3, FT3), reverse triiodothyronine (rT3), thyroid-stimulating hormone, and thyroxine binding globulin were measured in 14 newborn infants with severe respiratory failure (age 1-30 days) from samples collected before anesthesia for cannula placement, at 30, 60, and 360 min after initiation of ECMO, and on days 2, 4, 6, and 8. The patients were divided into survivors and non-survivors for statistical analyses. No differences were noted between survivors and non-survivors in the pre-ECMO mean serum concentrations of the thyroid function tests analyzed. In nine survivors, mean serum T4, FT4, T3, FT3, and rT3 all declined significantly within 30-60 min after initiation of ECMO, compared to baseline values. The values for all mean serum concentrations recovered completely and exceeded baseline between days 2 and 8. In five non-survivors, the decline of all mean serum values was not statistically significant and recovery to baseline was not achieved. The ratios of mean serum concentration of rT3/FT3 were significantly different between survivors and non-survivors across all times during the ECMO course (p < 0.0005). These findings indicate that abnormalities in thyroid function occur in neonates with severe respiratory failure on ECMO and that the rT3/FT3 ratio correlates with prognosis over the ECMO course. Survival was associated with a significant reduction of serum thyroid hormone concentrations followed by recovery. We speculate that, in neonates with respiratory failure on ECMO, adaptive mechanisms which enhance survival include the capacity to down-regulate the pituitary-thyroid axis.

Extracorporeal Membrane Oxygenation↗
PubMed2000

Bilateral microphthalmos with colobomatous orbital cyst and de-novo balanced translocation t(3;5).

A term Caucasian male infant, born to a healthy non-related couple, was noted at birth to have bilateral edema and bluish discoloration of the lower eyelids. On physical examination, the eye globes were not visualized and hypertelorism was noted. Radiological imaging revealed large bilateral orbital cysts, microphthalmos, and severe optic nerve hypoplasia. Histological study of the excised orbital masses showed cysts lined by primitive, immature retinal tissue which contained neuroglial elements and scattered dysplastic rosettes. Chromosome analysis revealed an apparent balanced reciprocal translocation between the long arm of chromosome 3 and 5, i.e. 46, XY, t (3; 5) (q27; q11.2). Chromosome studies in parents were normal. To our knowledge, the association of this balanced translocation and microphthalmos with cyst has not been previously described in the English literature.

Chromosomes, Human, Pair 3↗
PubMed1997

Retaining extracorporeal membrane oxygenation cannulae after extracorporeal support in the neonate: is it safe?

The retention of extracorporeal membrane oxygenation (ECMO) cannulae of ECMO is discontinued was originally developed to avoid reexploration of the neck in patients who may require a second course of ECMO. Because of the incidence, at the authors' institution, of thrombi noted on the ends of retained cannulae and their potential to cause significant morbidity, a critical review of this procedure was initiated. A telephone survey of 72 Extracorporeal Life Support Organization (ELSO) centers was conducted, and ELSO registry forms were requested for patients who had their cannulae retained. Twenty-four of these centers had performed the procedure of retaining ECMO cannulae. There were 324 neonatal and pediatric patients who had their cannulae retained, with 41 patients (12%) requiring a second course of ECMO and 17 of 41 (41%) surviving the second course. Twelve of the 24 ELSO centers that retain cannulae have reported complications. Analyses of the patients who had their cannulae retained showed that the three best predictors for requiring a second course of ECMO were the diagnosis of congenital diaphragmatic hernia (CDH) a high oxygenation index just before the initiation of ECMO, and a lengthy first ECMO course. The only difference between the survivors and nonsurvivors of the second course of ECMO was the length of the first ECMO course (P < .05). Five of the 25 patients who required two courses of ECMO had serious complications from their retained cannulae and all were nonsurvivors. The authors conclude that patients with retained ECMO cannulae are at high risk for developing thrombi, which can lead to severe embolic events. Therefore, the procedure of retaining cannulae should only be used in patients at high risk for requiring a second course of ECMO and not for the convenience of surgical availability to remove the cannulae.

Catheters, Indwelling↗
PubMed1997

Survival of patients with congenital diaphragmatic hernia during the ECMO era: an 11-year experience.

BACKGROUND/PURPOSE: Congenital diaphragmatic hernia (CDH) is associated with significant mortality and morbidity. To evaluate the impact of extracorporeal membrane oxygenation (ECMO) on survival, a review of our experience with CDH patients was initiated. METHODS: The authors performed a retrospective nonrandomized analysis of 98 consecutive CDH patients who were ECMO candidates, and were symptomatic within the first day of life, and underwent repair between May 1985 and May 1996. The patients were divided into three groups: Group 1 (n = 38) refers to patients who were clinically stable and underwent repair before 48 hours of age and did not need ECMO rescue; Group 2 (n = 29) consists of patients who underwent repair but required ECMO rescue; and Group 3 (n = 31) refers to patients who met ECMO criteria preoperatively and required ECMO for stabilization and later underwent repair on ECMO. The Kaplan-Meier survival graph was used for survival analysis. RESULTS: During the 11-year span, the overall survival rate of all CDH patients was 72% (71 of 98). The survival rate of patients who did not require ECMO support was 92% (35 of 38), whereas patients who required ECMO after repair had a 72% (21 of 29) survival rate. These were compared with a 48% (15 of 31) survival rate for those undergoing repair on ECMO. The differences in survival among the three groups were statistically significant using the log-rank test (P = .0018). CONCLUSIONS: Survival was significantly better for infants who underwent successful repair without ECMO than those who required ECMO rescue pre- or postrepair. The overall improved survival of CDH patients to 72% compared with historical controls of 38% to 58% may be attributed to ECMO, but the requirement of ECMO before repair, as well as the presence of congenital anomalies (P < .01), prematurity (P < .01), the need for a Gore-Tex patch at repair (P < .05), prenatal diagnosis at less than 25 weeks' gestation (P < .01), and the occurrence of an intracranial hemorrhage (P < .01), decreases the chances of survival.

Extracorporeal Membrane Oxygenation↗
PubMed1997

Preoperative versus postoperative extracorporeal life support in neonatal cardiac patients.

The aim of this study is to document our experience with the use of extracorporeal life support (ECLS) in the neonatal cardiac patient, to detect differences in the morbidity and mortality between patients who required ECLS preoperatively and those who required ECLS postoperatively, and to determine the long-term effects of these morbidities. A chart review was undertaken of all neonatal cardiac patients who required ECLS between May 1985 and July 1994 at Kosair Children's Hospital, Louisville, Kentucky. Twenty-three neonatal cardiac patients had received preoperative or postoperative ECLS with an overall survival rate of 35%. Our preoperative and postoperative patients had similar demographics, diagnoses, decannulation rates and survival rates. However, patients receiving postoperative ECLS more frequently required more than two inotropes (p < 0.001), had an increased incidence of renal failure (p < 0.02), had more central nervous system abnormalities on brain imaging studies (p < 0.004), and had a longer hospital stay (p < 0.05). Follow-up testing of survivors yielded normal Bayley Scale of Infant Development (BSID) scores in half of the patients. Survival in the two groups was similar, but a significant difference in morbidity was found. Except for severe intracranial abnormalities, the morbidity was shown to be reversible on follow-up examination. We recommend the continued use of ECLS for neonatal cardiac patients who require preoperative or postoperative support even when severe renal failure ensues or minor abnormalities are detected on brain imaging studies.

Acute Kidney Injury↗
PubMed1996

Response to high frequency jet ventilation may predict the need for extracorporeal membrane oxygenation.

The aim of this study was to determine predictors of response whilst using high frequency jet ventilation (HFJV) for infants in intractable respiratory failure, in order to avoid the utilization of extracorporeal membrane oxygenation (ECMO). We reviewed patient demographics, ventilator parameters, blood gas values, length of oxygen therapy and use of surfactant and outcome, in infants given a 4 h trial of HFJV as the minimum to eliminate those infants where HFJV is used as a bridge to ECMO. The study was carried out in the neonatal intensive care nursery at Kosair Children's Hospital in Louisville, Kentucky, which provides high frequency ventilation and ECMO. Thirty infants who were eligible for ECMO and who met the study criteria were divided into two groups based upon response to HFJV. Twenty two infants responded to HFJV and eight nonresponders required ECMO after a trial of HFJV. Infants responding during HFJV demonstrated a significant decrease in oxygenation index without an escalation of mean airway pressure within 4 h after the initiation of HFJV. These infants had lower birth weights and an increased incidence of respiratory distress syndrome. No statistical differences were found in length of ventilation, days of oxygen therapy or duration of HFJV between the groups. Infants in intractable respiratory failure, who are eligible for extracorporeal membrane oxygenation, should receive a trial of high frequency jet ventilation, especially if the cause is respiratory distress syndrome unresponsive to surfactant therapy. During high frequency jet ventilation, the oxygenation index and mean airway pressure should be monitored serially, since they may predict the need for extracorporeal membrane oxygenation.

Extracorporeal Membrane Oxygenation↗
PubMed1992

Surgical complications and procedures in neonates on extracorporeal membrane oxygenation.

We report our experience from May 1985 to January 1991 with surgical complications and procedures performed in neonates on extracorporeal membrane oxygenation (ECMO) (218 venoarterial and 7 venovenous bypass). Eleven children older than 1 month were excluded. Total complications were 96 in 67 patients and included: bleeding (37), problems with initial cannula placement (17), thrombus formation (15), hemothorax, pneumothorax, or effusions (11), mechanical problems (11), and miscellaneous (5). Forty-eight procedures were performed in 37 patients while on ECMO. These were recannulation or reposition of cannulas (14), tube thoracostomy (11), cardiac surgery (6), cardiac catheterization (4), repair of congenital diaphragmatic hernia (5), thoracotomy (4), and others. Twenty-eight complications occurred in 15 of the 27 patients who died. Mortality rate was 12% for the entire group. Primary causes of death were hypoplastic lung (11), cardiac (8), sepsis (4), intraventricular hemorrhage (2), and pulmonary hypertension (2). No deaths were due solely to complications except for the two patients with intraventricular hemorrhage. Mortality in neonates who had complications while on ECMO was significantly higher (P less than .005) than in patients without complications. Hemorrhagic and thoracic complications were associated with higher mortality (P less than .001). Mortality was not affected by mechanical problems, thrombus formation, or catheter-related problems. While on ECMO cardiac defects, diaphragmatic hernia, lobar emphysema, and other conditions can be safely corrected. The use of echocardiography to position the cannulas, better control of coagulation factors and improvement in equipment may ultimately decrease complications.

Evaluation Studies as Topic↗
PubMed1992

Extracorporeal membrane oxygenation and early-onset group B streptococcal sepsis.

Recently, extracorporeal membrane oxygenation (ECMO) has been used as rescue therapy for newborns with overwhelming early-onset group B streptococcal sepsis. To determine which clinical factors best predict mortality and to evaluate the outcome of this therapy, a retrospective examination of the clinical course and outcome of ECMO-eligible newborns with early-onset group B streptococcal sepsis was undertaken. The study period was divided into two phases based on when ECMO was initially used at Kosair Children's Hospital as therapy for septic neonates. Phase 1 (pre-ECMO) was the period from January 1, 1982, through June 15, 1986, and phase 2 (ECMO) from June 16, 1986, through December 31, 1989. Newborns with gestational age greater than or equal to 34 weeks, birth weight greater than or equal to 2000 g, and evidence of early-onset group B streptococcal sepsis were eligible for study. Only newborns who received mechanical ventilation were evaluated. Sixteen patients from phase 1 met the above criteria. Of those, 10 exhibited no sign of hypotension and all survived. Of the 6 patients with hypotension, 3 died. Forty patients were identified from phase 2. Seven patients remained normotensive and all survived. Thirty-three patients were hypotensive, of which 15 received ECMO and 13 survived. Of the 18 who did not receive ECMO, 7 died. Regarding all hypotensive newborns, those who did not receive ECMO had a trend toward lower survival (P less than .06) and were more likely to die if they were of lower birth weight, manifested a persistent acidosis (pH less than or equal to 7.25), and had an absolute neutrophil count less than 500 cells/mm3.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1991

Electromechanical dissociation in newborns treated with extracorporeal membrane oxygenation: an extreme form of cardiac stun syndrome.

OBJECTIVE: To recognize cardiac stun syndrome and electromechanical dissociation in patients receiving extracorporeal membrane oxygenation (ECMO), and to define patients at risk. DESIGN: Retrospective review. SETTING: Tertiary neonatal ICU. PATIENTS: Four newborn patients with cardiorespiratory failure who developed signs of cardiac stun syndrome and electromechanical dissociation early in the ECMO course. MEASUREMENTS AND MAIN RESULTS: Initially, these patients had metabolic acidosis, chest roentgenograms showing pulmonary granularity and moderate cardiomegaly, and symptoms of severe respiratory distress. Cardiac dysfunction was apparent after ECMO was begun, with poor perfusion, pale color, narrow pulse pressure, and tachycardia despite normovolemia. Within 1 to 2 hrs, electromechanical dissociation occurred manifested by the absence of pulse pressure, palpable pulse, cardiac sounds, and apical impulse while on 50% to 70% bypass. All patients survived. INTERVENTIONS: Patients received ECMO, calcium gluconate, sodium bicarbonate, and dobutamine. CONCLUSIONS: Patients with cardiac stun syndrome have symptoms similar to severe respiratory distress syndrome, and may require ECMO support. In the ECMO patient, cardiac stun syndrome and electromechanical dissociation can be confused with low circuit volume, pneumothorax, or cardiac tamponade. Early recognition of electromechanical dissociation may improve care and outcome. Cardiac stun syndrome can be treated successfully with ECMO.

Extracorporeal Membrane Oxygenation↗
PubMed1991

Effect of extracorporeal membrane oxygenation on leukocyte function in neonates.

The impact of extracorporeal membrane oxygenation (ECMO) on neonatal leukocyte content and function was examined in six patients. Patients were treated with ECMO for a mean of 134 h (range 44-246 h). Absolute neutrophil counts decreased from 14679 +/- 2291/mm3 to 7791 +/- 1672/mm3 after 2 h of ECMO. However, neutrophil phagocytosis and oxidative burst remained unchanged during the first 48 h of bypass. Monocyte counts also decreased during bypass, and at times were undetectable in 50% of patients. Monocyte HLA-DR content was decreased compared to normal cord blood prior to initiation of ECMO, and remained low throughout ECMO. However, the content increased significantly after termination of bypass. Plasma C3a levels increased transiently, paralleled by an increase in neutrophil CR3 expression. While moribund infants had some impairment of host defenses prior to ECMO, there was no further impact of ECMO per se on the parameters measured, other than transient complement activation and decreased monocyte counts.

Complement Activation↗
PubMed1991

Lateralization of brain lesions following extracorporeal membrane oxygenation.

The cranial ultrasound and computed tomography scan films of 180 patients who underwent extracorporeal membrane oxygenation were reviewed. Sixteen patients were considered to have moderate to severe brain lesions. Of these, 6 were ischemic and 10 were hemorrhagic. Five (83.3%) of the 6 ischemic lesions involved the right side and only 1 ischemic injury occurred on the left. Seven (70%) of the 10 hemorrhagic lesions occurred solely or predominantly on the side opposite the carotid ligation and 3 were found on the same side as the ligation. One patient suffered a right temporal hemorrhage following cannulation of the left common carotid artery. There was no predominance of brain lesions for either side when both hemorrhagic and ischemic lesions were combined. These observations implicate alterations in cerebrovascular hemodynamics accompanying carotid ligation and reperfusion in the pathogenesis of central nervous system lesions associated with the extracorporeal membrane oxygenation procedure. It is suggested that systematic classification of brain lesions associated with extracorporeal membrane oxygenation be made to get a better understanding of their pathology.

Brain Ischemia↗
PubMed1989

Acute effects of changing plasma osmolality and colloid oncotic pressure on the formation of brain edema after cryogenic injury.

The cerebral effects of alterations in plasma osmolality (Osm) and colloid oncotic pressure (COP) were examined in normocarbic, normothermic, pentobarbital-anesthetized rabbits that had been subjected to cryogenic brain injury. Monitored variables in all animals included mean arterial, right atrial, and intracranial pressures (MAP, CVP, and ICP), electroencephalographic (EEG) recordings, and cerebral blood flow (CBF). When surgical preparation was complete, a left parietal lesion was produced with liquid nitrogen. Group 1 (control, n = 8) animals subsequently received only maintenance fluids [lactated Ringer's solution (LR)]. One hour after injury, 3 other groups of animals underwent 45 minutes of plasmapheresis, carried out by arterial phlebotomy (packed red cells returned), with separated plasma being replaced by one of three fluids given in amounts sufficient to maintain MAP and CVP at baseline values. The three fluids were 1) 6% hetastarch in hypo-osmotic LR [Group 2 (Hypo-Osm), n = 6; COP = 21 mm Hg, Osm = 130 mOsm/kg]; 2) iso-osmotic LR [Group 3 (Hypo-COP), n = 8; COP = 0; Osm = 305]; and 3) 6% hetastarch in iso-osmotic LR [Group 4 (Iso-Osm/COP), n = 8; COP = 21, Osm = 310]. The animals were killed by exsanguination 25 minutes after completion of plasmapheresis. The brain was removed, the hemispheres separated, weighed, and sliced, and the specific gravities (SpGr) of the regional tissue determined. There were no differences in MAP, CVP, regional CBF, or EEG activity among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Varicella exposure in a neonatal intensive care unit: case report and control measures.

Forty-six infants in a neonatal intensive care unit and 138 health care workers were exposed to a pediatric medical resident during the prodromal period and the early days of unrecognized varicella. An attempt was made to prevent an outbreak of additional cases by the institution of emergency control measures. These measures included rapid identification of varicella antibody status in exposed neonates, varicella antibody testing of health care workers with unknown or uncertain history of varicella, prompt administration of varicella zoster immune globulin to potentially susceptible persons, and cohorting neonates on the basis of exposure and antibody status. Passive maternal antibody was detected in 44 of the neonates. Of 27 health care workers who reported either a negative or an uncertain history of varicella, 26 had detectable antibody. No overt cases of varicella occurred in exposed patients or personnel.

Adult↗
PubMed1988

Infant orthotopic cardiac transplantation.

Infant orthotopic cardiac transplantation has been recently applied to various forms of congenital heart disease with encouraging short-term results. Between June 1986 and September 1987 we evaluated 16 infants for orthotopic cardiac transplantation. Fourteen had hypoplastic left heart syndrome, one had endocardial fibroelastosis with aortic atresia, and one had anomalous pulmonary arterial origin of the left main coronary. Eight families accepted the treatment program and eight families refused (two because of associated anomalies and six on philosophical grounds). Of the eight patients who were candidates for orthotopic cardiac transplantation, one died 6 hours after diagnosis, one was allowed to die after 60 days because of acquired neurologic complications, and another had congenital cytomegalic virus infection. The remaining five patients (four with hypoplastic left heart syndrome, one with anomalous pulmonary arterial origin of the left main coronary) had orthotopic cardiac transplantation. The operation was performed with absorbable polydioxanone suture with deep hypothermia and circulatory arrest in four neonates for hypoplastic left heart syndrome (average time 47 minutes) and bicaval cannulation and continuous bypass in one 11-month-old infant for anomalous origin of the left main coronary. In-house retrieval was used in all. One neonate died of complications as a result of pretransplant donor heart dysfunction and size discrepancy, whereas the remaining three neonates and one infant survived and are home 23 months, 12 months, and 8 months (the patients with hypoplastic left heart syndrome) and 17 months (the patient with anomalous origin of the left main coronary) postoperatively. Triple-drug immunosuppression included cyclosporine, azathioprine, and prednisone. Rejection was diagnosed by clinical evaluation of child activity and monocyte cell cycle analysis from peripheral blood samples without myocardial biopsies. Routine echocardiograms, electrocardiograms, and chest x-ray films were not helpful. Six episodes of rejection were successfully treated in four patients. Twelve-month postoperative catherization in one patient (hypoplastic left heart syndrome) showed appropriate graft growth, no aortic or pulmonary anastomotic strictures, normal right and left ventricular function, and no coronary artery disease. We conclude that infant orthotopic cardiac transplantation is an acceptable procedure for severe forms of untreatable congenital heart disease. The excellent short-term results warrant continued application of orthotopic cardiac transplantation.

Acute Kidney Injury↗
PubMed1988

Right atrial thrombus formation screening using two-dimensional echocardiograms in neonates with central venous catheters.

Two-dimensional echocardiograms were used to prospectively screen 49 patients with 56 central venous catheters for right atrial thromboses from October 1985 to May 1986. All but four patients received a two-dimensional echocardiogram prior to insertion of the catheter. Once the catheters were in place, two-dimensional echocardiograms were performed no later than 3 weeks after insertion and then every 14 days until the catheter was removed. A single thrombus was detected 79 days after catheter placement (an incidence of 1.8%). Previous recommendations for weekly screening with two-dimensional echocardiogram were based on case reports alone. The 95% confidence limits for a negative two-dimensional echocardiogram result suggest that the initial two-dimensional echocardiogram screen for thrombus be obtained no sooner than 3 weeks after catheter insertion. In addition, significant gastrointestinal disease requiring operative intervention was present in 10 of 11 previous case reports as well as in our patient. Further studies with larger sample sizes are needed to determine whether subgroups of infants exist who are at a relatively higher risk for right atrial thrombus formation.

Catheterization, Peripheral↗