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Biomedical subjects

T Hoehn

Publications and source records attributed to T Hoehn.

At least 19 recordsLinked to original sources
PubMed2001

Colonic pneumatosis intestinalis in preterm infants: different to necrotising enterocolitis with a more benign course?

UNLABELLED: Necrotising enterocolitis (NEC) is the predominant immaturity-associated disease of the bowel in the preterm neonate and leads to substantial mortality and long-term morbidity. Diagnostic features of NEC include, apart from the clinical presentation, laboratory and radiological parameters. Pneumatosis intestinalis (PI) on abdominal radiographs is regarded as a criterion of definitive proof for this disease entity. The objective of this presentation is to link the topographic pattern of PI to the clinical course in cases of suspected NEC. We report two cases of radiological appearance of colonic PI indicative of NEC without associated laboratory and/or macroscopic evidence of the disease, and with minor clinical symptoms only. Data from animal studies indicate that decreased blood supply to the small bowel is associated with more extensive bowel damage as compared to impaired colonic perfusion. Therefore the topographical distribution of PI might be a more specific sign as the general presence or absence of PI. CONCLUSION: The topographical pattern of pneumatosis intestinalis may be predictive of the clinical course of inflammatory bowel disease in preterm infants.

Diagnosis, Differential↗
PubMed2001

Hyperoxia- and hypoxia-mediated activation of polymorphonuclear leukocytes: a comparison of cord and adult venous blood.

BACKGROUND: Among the most prominent changes occurring in newborn infants is the exposure of tissues and blood cells to increased oxygen tension. This increase is even more pronounced in neonatal resuscitation using 100% oxygen, currently recommended in the published guidelines. OBJECTIVE: To analyse the response of neonatal and adult polymorphonuclear neutrophils (PMN) to high or low oxygen tension in vitro. MATERIALS: Neonatal cord blood and adult venous blood without previous contact to ambient air was exposed to 0, 21, or 100% oxygen for 30 min followed by incubation for up to 24 h. METHODS: Flow cytometry was used to assess PMN activation as indicated by downregulation of L-selectin expression. Cell viability was quantified by the amount of propidium iodide uptake. RESULTS: In adult PMN, L-selectin downregulation was greatly accelerated by hypoxia (PO2=27.2+/-3.4 mmHg) compared with both normoxia (PO2=71.0+/-11.0 mmHg) or hyperoxia (PO2=653.2+/-9.4) (P<0.05). In contrast, hyperoxia was the most potent stimulus for cord blood PMN, compared with both normoxia and hypoxia (P<0.05). Evidence of necrosis as indicated by positive staining for propidium iodide was similar in cord blood (10 h: 5.83% in oxygen) and in adult blood (10 h: 6.45% in oxygen). No differences were found between exposure to hypoxia, normoxia, or hyperoxia. CONCLUSION: Oxygen exposure of neonatal PMN leads to a more pronounced activation as compared with adult cells. Exposure towards high concentrations of oxygen may contribute to inflammatory processes during early neonatal life.

Adult↗
PubMed2001

In-vitro activation of complement system by lactic acidosis in newborn and adults.

INTRODUCTION: Complement activation occurs secondary to a variety of external stimuli. Lactic acidosis has been previously shown to activate the complement factors C3a and C5a. In the present investigation we examined the differential effect of lactic acidosis on anaphylatoxin levels in cord and adult blood. Furthermore we aimed to determine if the entire complement cascade could be activated by lactic acidosis. METHODS: Cord and adult blood samples (n = 20 each) were collected and incubated for one hour in either untreated condition or with the addition of lactate in two concentrations (5.5 mmol/l vs. 22 mmol/l). Following incubation, levels of C3a, C5a and sC5b-9, and blood gas parameters were determined. RESULTS: Anaphylatoxin (C3a and C5a) and sC5b-9 levels increased with the addition of lactate in a dose-dependent manner in cord and adult blood (C3a: 1 h, 5.5 mmo/l, 22 mmol/l: 418/498/622 microg/l in cord blood; 1010/1056/1381 microg/l in adult blood, p<0,05; similar results were found for C5a and sC5b-9). CONCLUSION: Lactic acidosis leads to an activation of the entire complement system in neonates and in adults. This activation is dose-dependent and more pronounced in adults as compared to neonates.

Acidosis, Lactic↗
PubMed2001

Focal congenital alveolar proteinosis associated with abnormal surfactant protein B messenger RNA.

Two siblings presented with typical clinical features of congenital pulmonary alveolar proteinosis (PAP). Necropsy of one sibling revealed scattered foci of the diagnostic histologic changes in the lung tissue. In contrast to infantile and adult PAP, focal distribution is uncommon in congenital PAP. Defective expression of the granulocyte-macrophage colony-stimulating factor receptor was ruled out. The surfactant protein B (SP-B) content in the lung tissue of the autopsied patient was low, and a deletion in the SP-B messenger RNA was detected. We speculate that the PAP in our patients was related to the reduced quantity and/or to the altered quality of SP-B.

Chromosome Deletion↗
PubMed2001

Response to inhaled nitric oxide in premature and term neonates.

Inhaled nitric oxide (iNO) has emerged as a promising therapeutic agent in the treatment of persistent pulmonary hypertension of the newborn. Several theories exist regarding causes of both response and nonresponse to iNO. Clinical trials differentiate disease entities (primary vs secondary persistent pulmonary hypertension associated with meconium aspiration syndrome, pneumonia or congenital diaphragmatic hernia) and their specific response rates. iNO combined with high-frequency ventilation appears to be superior to inhalation of nitric oxide (NO) during conventional ventilation. Little is known regarding the role of the degree of lung expansion and its modification -- no matter what mode of ventilation is applied. Gestational age plays an important role in relation to the potential adverse effects of NO. Of particular concern in the premature neonate is the effect of NO on bleeding time and the inhibition of platelet aggregation. Those potentially hazardous effects need to be carefully weighed against early intervention with iNO at a comparably low oxygenation index in order to prevent the vicious cycle of hypoxaemia and subsequent increased right-to-left shunting. Further studies are required to determine the optimal timing, mode of delivery and mode of ventilation used with iNO therapy in order to optimise the response of premature and term neonates.

Animals↗
PubMed2001

Role of erythromycin for treatment of incipient chronic lung disease in preterm infants colonised with Ureaplasma urealyticum.

Ureaplasma urealyticum is frequently isolated from tracheal aspirates of very low birthweight infants who go on to develop chronic lung disease. The use of erythromycin has been advocated in ventilated very low birthweight infants who are colonised with U. urealyticum, although the association between U. urealyticum and chronic lung disease remains controversial. There are only two randomised, controlled trials involving a total of 37 U. urealyticum-positive very low birthweight infants. Both trials failed to demonstrate a reduction in the incidence of chronic lung disease after 7 or 10 days of erythromycin. On the other hand, there are reports of rare but serious adverse effects of erythromycin in newborn infants including sudden cardiovascular compromise and hypertrophic pyloric stenosis. We conclude that, at present, there is insufficient evidence to support the use of erythromycin for the treatment of incipient chronic lung disease in very low birthweight infants colonised with U. urealyticum.

Anti-Bacterial Agents↗
PubMed2001

Effectiveness of intravaginal progesterone inserts and FSH for inducing synchronized estrus and increasing lambing rate in anestrous ewes.

The objectives of this study were to determine whether a new progesterone (P4)-releasing intravaginal insert would induce fertile estrus and whether FSH combined with the insert would increase prolificacy in anestrous ewes introduced to rams. Ewes of mixed breeding on six farms were assigned to four randomized treatments: control (C), n = 73; 12 d P4 (polycapralactone [PCL] insert with 0.82 g P4), (P12), n = 73; 12 d P4 plus i.m. FSH (Folltropin, 55 mg NIH-FSH-P1 equivalent) in propylene glycol, 24 h before insert removal, (P12F), n = 71; and 5 d P4 plus FSH (P5F), n = 77. Growth and ovulation of follicles were observed ultrasonographically in 20 ewes at four farms (five/treatment) at insert removal and 36, 48, 72, and 96 h later. Intact rams (1:15 ewes in multiple-sire groups) were joined at insert removal, and raddle marks were observed every 12 h for 5 d. On d 26 to 30, rams were removed; ewes were examined for pregnancy then and 20 d later. Percentage of ewes marked by rams was greater in P4-treated (66 to 79%) than in C (12%; P < 0.01) ewes and in P5F (79%) than in P12F (66%; P < 0.05). Diameters of largest follicles at insert removal were greater (P < 0.05) in P4-treated (5.5 +/- 0.2) than in C ewes (4.8 +/- 0.2). Progesterone increased numbers of follicles > 3 mm (P < 0.01) or ovulated (P < 0.05; 2.6 +/- 0.6 vs 1.3 +/- 0.6 in C ewes) and FSH increased number of follicles > 3 mm (P < 0.05). In FSH-treated ewes, ovulation rate tended to be greater after treatment with P4 for 5 than for 12 d (P = 0.09, 3.3 +/- 0.6 and 2.2 +/- 0.4, respectively). More P4-treated than C ewes lambed (P < 0.01) to the first (38 to 45 vs 0%) or both (63 to 66 vs 41%) service periods. Prolificacy (first service) did not differ between FSH-treated ewes (P12F + P5F; 1.8 +/- 0.1) and ewes treated with P4 only (P12; 1.6 +/- 0.1). However, FSH increased prolificacy to first service (1.8 +/- 0.1) over prolificacy to second service (C ewes 1.5 +/- 0.1; P < 0.05, and all ewes 1.4 +/- 0.1; P < 0.01). Pregnancy retention did not differ among treatments but was greater (P < 0.01) in ewes that conceived at the first (90.9 +/- 3.7) than at the second (72.5 +/- 3.3) service period. In conclusion, a PCL insert in combination with ram introduction at insert removal was more effective than ram introduction alone to induce synchronized estrus and ovulation and to yield pregnancy after one or two service periods. Treatment with P4 for 5 d was as effective as for 12 d to induce fertile estrus in FSH-treated anestrous ewes.

Administration, Intravaginal↗
PubMed2000

Comparison of noise levels caused by four different neonatal high-frequency ventilators.

OBJECTIVE: To test the hypothesis that neonatal high-frequency ventilators create different noise levels depending upon ventilator settings and device-specific properties. MATERIALS: Three neonatal ventilators with built-in high-frequency options (Babylog 8000, Infant Star, Stephanie) and an exclusive high-frequency oscillator (SensorMedics 3100A). MEASUREMENTS: Noise levels were recorded by a microphone and measured by a decibel recording device at a defined distance from a test lung. RESULTS: Noise levels were highest for the SensorMedics and the Babylog (70 dB and 62 dB, respectively). Whereas the SensorMedics increased noise production with amplitude, the Babylog remained at a constant level. The Infant Star (52 dB) and the Stephanie (54 dB) were significantly less noisy at their maximum levels of amplitude (40 mbar and 50 mbar, respectively). CONCLUSION: Most levels recorded were below those measured within an incubator without the use of a ventilator. We conclude that neonatal high-frequency ventilators do not represent a major contribution to noise levels for newborns in neonatal intensive care units (NICUs).

Equipment Design↗
PubMed2000

Chest physiotherapy in mechanically ventilated children: a review.

OBJECTIVE: Many physicians, nurses, and respiratory care practitioners consider chest physiotherapy (CP) a standard therapy in mechanically ventilated children beyond the newborn period. CP includes percussion, vibration, postural drainage, assisted coughing, and suctioning via the endotracheal tube. DATA SOURCES: We searched the medical literature by using the key words "chest physiotherapy" and "chest physical therapy" (among others) by means of the MEDLINE and Current Contents databases. STUDY SELECTION: Because of the paucity of objective data, we examined all reports dealing with this topic, including studies on adult patients. For data extraction, not enough material existed to perform a meta-analysis. DATA SYNTHESIS: Despite its widespread use, almost no literature dealing with this treatment modality in pediatric patients exists. Studies with mechanically ventilated pediatric and adult patients have shown that CP is the most irritating routine intensive care procedure to patients. An increase in oxygen consumption often occurs when a patient receives CP accompanied by an elevation in heart rate, blood pressure, and intracranial pressure. CP leads to short-term decreases in oxygen, partial pressure in the blood, and major fluctuations in cardiac output. Changes in these vital signs and other variables may be even more pronounced in pediatric patients because the lung of a child is characterized by a higher closing capacity and the chest walls are characterized by a much higher compliance, thus predisposing the child to the development of atelectasis secondary to percussion and vibration. CONCLUSION: CP in mechanically ventilated children may not be considered a standard therapy. Controlled studies examining the impact of CP on the duration of mechanical ventilatory support, critical illness, and hospital stay are needed.

Adult↗
PubMed2000

Timing of surfactant administration determines its physiologic response in a rabbit model of airway lavage.

Surfactant response depends on timing of surfactant administration in infants with respiratory distress syndrome (RDS). We performed lung function studies in an animal model to describe the underlying differences in response related to gas exchange, lung volume and lung mechanics comparing early and late surfactant administration protocols. Young New Zealand rabbits were made surfactant deficient by repeated airway lavage with warm saline until the a/A O(2) ratio decreased to </=0.12. A natural ovine surfactant was administered at 1 h (early intervention) or at 3 h (late intervention) after the last lavage. Functional residual capacity (FRC), a/A O(2) ratio, effective breath fraction (EBF = V(A)/V(T)), ventilation efficiency index (VEI), dynamic compliance (C(rs)), nitrogen clearing index (NCI) and specific (volumic) compliance (sC(rs) = C(rs)/FRC) were followed for 2 h after surfactant administration. FRC, a/A O(2) ratio, VEI, C(rs) and sC(rs) were all significantly different between the two intervention groups in favor of the surfactant administration protocol at 1 h after lavage. EBF and NCI were not affected by timing of surfactant administration. We conclude that early surfactant administration elicits a superior response related to gas exchange, lung volume and lung mechanics in this animal model. These findings are in line with the more pronounced surfactant effects in the clinical setting when premature infants with RDS are treated using early intervention protocols.

Animals↗
PubMed2000

Inhaled nitric oxide in premature infants--a meta-analysis.

The role of inhaled nitric oxide (iNO) in the treatment of severe hypoxemic respiratory failure of term neonates has been firmly established in several randomized trials. In contrast, the use of iNO in premature newborns has remained controversial. As of 1999, there are data of three randomized controlled trials involving a total of 210 infants below 33 weeks of gestation. None of the trials was able to demonstrate a benefit of iNO with respect to mortality or chronic lung disease. We performed a meta-analysis of the three published trials. Of 111 infants receiving iNO, 44 deaths were observed, compared to 40 of 99 control infants (p = 0.91). The odds ratio in favor of iNO was 0.97 (95% confidence interval 0.54-1.75). There was also no significant difference for treatment failure, defined as death or chronic lung disease (iNO: 32 of 111 infants versus control: 34 of 99, p = 0.39, odds ratio 0.77, 95% confidence interval 0.41-1.45). The rates of intracranial hemorrhage were similar in both groups (35 of 111 infants receiving iNO vs 25 of 99 controls, p = 0.33, odds ratio 1.37, 95% confidence interval 0.69-2.74). We conclude that the use of inhaled nitric oxide may improve oxygenation but not survival in preterm infants with severe hypoxemic respiratory failure.

Administration, Inhalation↗
PubMed1999

Fatal rupture of a sacrococcygeal teratoma during delivery.

We report the case of premature infant born at 32 weeks' gestation with a sacrococcygeal teratoma diagnosed in utero. During delivery by cesarean section, profound bleeding due to rupture of the teratoma occurred. Despite volume expansion with saline, albumin, and whole blood, a satisfactory peripheral perfusion of the infant was only briefly achieved. Surgical intervention to stop the bleeding was unsuccessful. Resuscitation of the infant was discontinued after 55 minutes. The relevant literature is discussed, and suggestions for the management of infants with sacrococcygeal teratomas are made.

Cesarean Section↗
PubMed1999

Decrease in lung volume depends on end-expiratory pressure in a rabbit model of airway lavage.

BACKGROUND: In the past, the rabbit model of repeated airway lavage has been extensively used to induce a decrease in lung volume accompanied by impairment in lung mechanics and gas exchange. OBJECTIVES: The rationale of our study was to investigate the influence of different end-expiratory pressure (EEP) levels (0.4-4.2 cm H2O) on changes in functional residual capacity (FRC) and the efficacy of lavages administered. METHODS: Forty-five rabbits were subjected to 2-8 lavages with 20 ml/kg warm normal saline until arterial/alveolar oxygen tension (a/A ratio) had decreased to </=0. 12. RESULTS: FRC and dynamic compliance of the respiratory system (Crs) decreased significantly (both p < 0.001; from 19.1 +/- 4.2 to 10.5 +/- 5.6 ml/kg and from 1.17 +/- 0.27 to 0.47 +/- 0.10 ml/cm H2O, respectively, means +/- SD). The decrease in FRC was significantly influenced by EEP (-28.6 +/- 15.8% at EEP = 1 cm H2O vs. -58.7 +/- 12.9% at EEP = 3 cm H2O, p < 0.0001). There was a significant correlation between the number of lavages and EEP (p < 0.01), indicating that successive lavages at higher EEP became ineffective in lowering FRC compared to those at lower EEP. CONCLUSIONS: We conclude that the EEP levels used in this model are of critical importance for the prediction of a decrease in lung volume (FRC) and the efficacy of lavages.

Animals↗
PubMed1998

Rate of surfactant administration influences lung function and gas exchange in a surfactant-deficient rabbit model.

The aim of this study was to test whether the effect of surfactant treatment on lung function in a surfactant-deficient animal model can be influenced by the rate at which surfactant is administered. Surfactant deficiency was induced in 18 New Zealand white rabbits (weighing approx. 1 kg each) by lung lavage with normal saline. The arterial/alveolar oxygen ratio (a/A ratio), functional residual capacity (FRC), dynamic compliance of the respiratory system (Crs), tidal volume (V(T)), alveolar portion of the tidal volume (V(A)) and arterial P(CO2) (P(a,CO2)) were measured before and after lavage and 15, 30, 60, 90, and 120 min after administration of a single dose of surfactant (Survanta, 100 mg/kg). Two surfactant administration protocols were compared over a 2-h interval: an infusion lasting 4 min and an infusion over 2 min. Both administrations were given during continuous mechanical ventilation. The six lung function and gas exchange parameters improved significantly following surfactant administration over 2 min compared with a control group. However, only the a/A ratio and V(A) improved following the 4-min protocol. Comparison of the two intervention protocols yielded significantly differences in V(A) and P(a,CO2), favoring the shorter administration. These results support the hypothesis that fast (2 min) administration of surfactant will improve its distribution to formerly collapsed alveoli and results in better lung function, improved ventilation, and (to a lesser extent) better oxygenation than prolonged infusions (4 min).

Animals↗