The role of nitric oxide in the cardiopulmonary response to hypoxia in highland and lowland newborn llamas.

Key Points: Perinatal hypoxia causes pulmonary hypertension in neonates, including humans. However, in species adapted to hypoxia, such as the llama, there is protection against pulmonary hypertension. Nitric oxide (NO) is a vasodilatator with an established role in the cardiopulmonary system of many species, but its function in the hypoxic pulmonary vasoconstrictor response in the newborn llama is unknown.

Impediments to a unified international approach to the interpretation and management of intrapartum cardiotocographs.

There is much inconsistency in management recommendations for cardiotocograms by international organizations. Impediments to achieving consensus include disagreement on the spectrum of risk of fetal acidemia, different fetal heart rate pattern display due to differing chart paper speed, and the necessity for ancillary testing in confirming fetal acidemia.

Role of the RhoA/ROCK pathway in high-altitude associated neonatal pulmonary hypertension in lambs.

Exposure to high-altitude chronic hypoxia during pregnancy may cause pulmonary hypertension in neonates, as a result of vasoconstriction and vascular remodeling. We hypothesized that susceptibility to pulmonary hypertension, due to an augmented expression and activity of the RhoA/Rho-kinase (ROCK) pathway in these neonates, can be reduced by daily administration of fasudil, a ROCK inhibitor. We studied 10 highland newborn lambs with conception, gestation, and birth at 3,600 m in Putre, Chile.

Cardiovascular function in term fetal sheep conceived, gestated and studied in the hypobaric hypoxia of the Andean altiplano.

High-altitude hypoxia causes intrauterine growth restriction and cardiovascular programming. However, adult humans and animals that have evolved at altitude show certain protection against the effects of chronic hypoxia. Whether the highland fetus shows similar protection against high altitude gestation is unclear.

Should we really avoid giving oxygen to mothers with concerning fetal heart rate patterns?

We challenge a provocative article entitled "Oxygen for intrauterine resuscitation: of unproved benefit and potentially harmful" by Hamel et al in the August issue of the Journal. The authors contend there is no good evidence that oxygen administration to the mother of a fetus with a concerning fetal heart rate pattern prevents acidosis and that in theory such oxygen administration may actually or potentially do harm to the fetus. It is clear that oxygen is administered quite often to women in labor, especially to those with category II fetal heart rate patterns and, because more than 80% of women in labor have these patterns and the majority of these patterns are unlikely to be associated with significant fetal hypoxia, that such oxygen administration is greatly overused.

Mechanism of reduction of newborn metabolic acidemia following application of a rule-based 5-category color-coded fetal heart rate management framework.

Unlabelled: Abstracts Objective: We have reported a 7-fold reduction in newborn umbilical arterial (UA) metabolic acidemia after adoption of a rule-based 5-category color-coded fetal heart rate (FHR) management framework. We sought evidence for the relationship being causal by detailed analysis of FHR characteristics and acid-base status before and after training.

Methods: Rates of UA pH and base excess (BE) were determined over a 5-year period in a single Japanese hospital, serving mainly low-risk patients, with 3907 deliveries.

Melatonin improves cerebrovascular function and decreases oxidative stress in chronically hypoxic lambs.

Chronic hypoxia during gestation and delivery results in oxidative stress and cerebrovascular dysfunction in the neonate. We assessed whether melatonin, a potent antioxidant and potential vasodilator, improves the cerebral vascular function in chronically hypoxic neonatal lambs gestated and born in the highlands (3600 m). Six lambs received melatonin (1 mg/kg per day oral) and six received vehicle, once a day for 8 days.

Intrapartum management of category II fetal heart rate tracings: towards standardization of care.

There is currently no standard national approach to the management of category II fetal heart rate (FHR) patterns, yet such patterns occur in the majority of fetuses in labor. Under such circumstances, it would be difficult to demonstrate the clinical efficacy of FHR monitoring even if this technique had immense intrinsic value, since there has never been a standard hypothesis to test dealing with interpretation and management of these abnormal patterns. We present an algorithm for the management of category II FHR patterns that reflects a synthesis of available evidence and current scientific thought.

Store-operated channels in the pulmonary circulation of high- and low-altitude neonatal lambs.

We determined whether store-operated channels (SOC) are involved in neonatal pulmonary artery function under conditions of acute and chronic hypoxia, using newborn sheep gestated and born either at high altitude (HA, 3,600 m) or low altitude (LA, 520 m). Cardiopulmonary variables were recorded in vivo, with and without SOC blockade by 2-aminoethyldiphenylborinate (2-APB), during basal or acute hypoxic conditions. 2-APB did not have effects on basal mean pulmonary arterial pressure (mPAP), cardiac output, systemic arterial blood pressure, or systemic vascular resistance in both groups of neonates.

Interprofessional collaborative practice in obstetrics and midwifery.

As the health care system transforms to accommodate an increased need for primary care services and more patients, new models of health care delivery are needed that can provide quality health care services efficiently. An integrated collaborative practice of certified nurse-midwives, obstetrician-gynecologists, and perinatologists is best suited to meet the rapidly changing needs of the maternity health care delivery system. This article reviews the literature on interprofessional collaborative practice and describes the structure, function, and essential elements of successful collaboration in health care.

Immediate newborn outcome and mode of delivery: use of standardized fetal heart rate pattern management.

Objective: To determine whether a rule-based system for fetal heart rate interpretation can result in reduced metabolic acidemia without increasing obstetrical intervention.

Methods: Rates of vacuum-assisted delivery and Cesarean sections, and umbilical artery pH and base excess values were determined over a 5-year period in a single hospital with 3907 deliveries in Japan. Results were compared for 2 years before and 2 years after a 6-month training period in rule-based fetal heart rate interpretation.

The heme oxygenase-carbon monoxide system in the regulation of cardiorespiratory function at high altitude.

Pulmonary arterial hypertension is one of the most serious pathologies that can affect the 140 million people living at altitudes over 2500 m. The primary emphasis of this review is pulmonary artery hypertension in mammals (sheep and llamas) at high altitude, with specific focus on the heme oxygenase and carbon monoxide (HO-CO) system. We highlight the fact that the neonatal llama has neither pulmonary artery hypertension nor pulmonary vascular remodeling in the Andean altiplano.

Role of the α-adrenergic system in femoral vascular reactivity in neonatal llamas and sheep: a comparative study between highland and lowland species.

Using an integrative approach at the whole animal, isolated vessels, and molecular levels, we tested the hypothesis that the llama, a species that undergoes pregnancy under the influence of the chronic hypoxia of high altitude, delivers offspring with an increased α-adrenergic peripheral vascular reactivity compared with neonates from lowland species. We studied the femoral vascular response to acute hypoxia in vivo, the reactivity of femoral vessels ex vivo, and the expression of femoral α(1)-adrenergic receptor subtypes using RT-PCR in vitro. The increase in femoral resistance during hypoxia was 3.

Long-term exposure to high-altitude chronic hypoxia during gestation induces neonatal pulmonary hypertension at sea level.

We determined whether postnatal pulmonary hypertension induced by 70% of pregnancy at high altitude (HA) persists once the offspring return to sea level and investigated pulmonary vascular mechanisms operating under these circumstances. Pregnant ewes were divided into two groups: conception, pregnancy, and delivery at low altitude (580 m, LLL) and conception at low altitude, pregnancy at HA (3,600 m) from 30% of gestation until delivery, and return to lowland (LHL). Pulmonary arterial pressure (PAP) was measured in vivo.

Comparison of 5 experts and computer analysis in rule-based fetal heart rate interpretation.

Objective: The purpose of this study was to measure agreement among 5 expert clinicians and a computerized method with the use of a strict fetal heart rate classification method.

Study Design: Five providers independently scored 769 8-minute segments from the last 3 hours of 30 tracings with the use of a 5-tier color-coded framework that contains pattern descriptions and proposals for management. Computer analysis was performed with PeriCALM Patterns (PeriGen, Princeton, NJ) to detect and classify patterns.

Spontaneous in utero recovery of a fetus in a brain death-like state.

A healthy pregnant woman at 28 weeks of gestation was admitted with complete loss of fetal movement. Fetal heart rate (FHR) monitoring showed a fixed flat FHR pattern with no variability. Ultrasound examination revealed no fetal breathing movement.

The 2008 National Institute of Child Health and Human Development report on fetal heart rate monitoring.

Standardization of fetal heart rate (FHR) interpretation and management guidelines has been elusive, and no system is currently widely accepted in the United States. The recently summarized 2008 Eunice Kennedy Shriver National Institute of Child Health and Human Development workshop proposed a three-tier system of interpretation of FHR patterns, but left management recommendations to the professional associations. The middle tier, called indeterminate Category II, which contains the variant FHR patterns seen most frequently, is vast and heterogeneous.

Sildenafil reverses hypoxic pulmonary hypertension in highland and lowland newborn sheep.

Perinatal exposure to chronic hypoxia induces sustained hypertension and structural and functional changes in the pulmonary vascular bed. We hypothesized that highland newborn lambs (HLNB, 3600 m) have a higher pulmonary arterial pressure (PAP) due in part to a higher activity/expression of phosphodiesterase 5 (PDE5). We administered sildenafil, a PDE5 inhibitor, during basal and hypoxic conditions in the pulmonary hypertensive HLNB and compared them to lowland newborn lambs (LLNB, 580 m).

Carbon monoxide: a novel pulmonary artery vasodilator in neonatal llamas of the Andean altiplano.

Aims: To study the nitric oxide (NO) and carbon monoxide roles in the regulation of the pulmonary circulation in lowland and highland newborn sheep and llamas.

Methods And Results: We used neonatal sheep (Ovis aries) and llamas (Lama glama) whose gestation and delivery took place at low (580 m) or high (3600 m) altitude. In vivo, we measured the cardiopulmonary function basally and with a NO synthase (NOS) blockade and calculated the production of carbon monoxide by the lung.

The intrapartum deceleration in center stage: a physiologic approach to the interpretation of fetal heart rate changes in labor.

One of the most distinctive features of fetal heart rate recordings in labor is the deceleration. In clinical practice, there has been much confusion about the types of decelerations and their significance. In the present review, we examined uteroplacental perfusion in labor, describe the pathophysiologic condition of decelerations, and explain some of the reasons behind the confusion about the terminology.