Randomized trial of volume infusion during resuscitation of asphyxiated neonatal piglets

Despite its use, there is little evidence to support volume infusion (VI) during neonatal cardiopulmonary resuscitation (CPR). This study compares 5% albumin (ALB), normal saline (NS), and no VI (SHAM) on development of pulmonary edema and restoration of mean arterial pressure (MAP) during resuscitation of asphyxiated piglets. Mechanically ventilated swine (n=37, age: 8 +/- 4 d, weight: 2.2 +/- 0.7 kg) were progressively asphyxiated until pH <7.0, Paco2 >100 mm Hg, heart rate (HR) <100 bpm, and MAP <20 mm Hg. After 5 min of ventilatory resuscitation, piglets were randomized blindly to ALB, NS, or SHAM infusion. Animals were recovered for 2 h before euthanasia and lung tissue sampled for wet-to-dry weight ratio (W/D) as a marker of pulmonary edema. SHAM MAP was similar to VI during resuscitation. At 2 h post-resuscitation, MAP of SHAM (48 +/- 13 mm Hg) and ALB (43 +/- 19 mm Hg) was higher than NS (29 +/- 10 mm Hg; p=0.003 and 0.023, respectively). After resuscitation, SHAM piglets had less pulmonary edema (W/D: 5.84 +/- 0.12 versus 5.98 +/- 0.19; p=0.03) and better dynamic compliance (Cd) compared with ALB or NS (Cd: 1.43 +/- 0.69 versus 0.97 +/- 0.37 mL/cm H2O, p=0.018). VI during resuscitation did not improve MAP, and acute recovery of MAP was poorer with NS compared with ALB. VI was associated with increased pulmonary edema. In the absence of hypovolemia, VI during neonatal resuscitation is not beneficial.

Effect of resuscitation with 21% oxygen and 100% oxygen on NMDA receptor binding characteristics following asphyxia in newborn piglets

The present study investigated the effect of reventilation with 21% and 100% oxygen following asphyxia in newborn piglets on NMDA receptor binding characteristics, Na(+), K(+)-ATPase activity, and lipid peroxidation. After achieving a heart rate less than 60 beats per minute, asphyxiated piglets were reventilated with 21% oxygen or 100% oxygen. (3)[H]MK-801 binding showed the Bmax in the 21% and 100% groups to be 1.53 +/- 0.43 and 1.42 +/- 0.35 pmol/mg protein (p = ns). Values for Kd were 4.56 +/- 1.29 and 4.17 +/- 1.05 nM (p = ns). Na(+), K(+)-ATPase activity in the 21% and 100% groups were 23.5 +/- 0.9 and 24.4 +/- 3.9 micromol Pi/mg protein/h (p = ns). Conjugated dienes (0.05 +/- 0.02 vs. 0.07 +/- 0.03 micromol/g brain) and fluorescent compounds (0.54 +/- 0.05 vs. 0.78 +/- 0.19 microg quinine sulfate/g brain), were similar in both groups (p = ns). Though lipid peroxidation products trended higher in the 100% group, these data show that NMDA receptor binding and Na(+), K(+)-ATPase activity were similar following reventilation with 21% or 100% oxygen after a single episode of mild asphyxia.

Naloxone and epinephrine are equally effective for cardiopulmonary resuscitation in a rat asphyxia model

BACKGROUND

It is not known whether naloxone is as efficacious as epinephrine during cardiopulmonary resuscitation (CPR). The aim of the study was to compare the effects of naloxone and epinephrine on the outcomes of CPR following asphyxial cardiac arrest in rats.

METHODS

Cardiac arrest was induced with asphyxia by clamping the tracheal tubes. Twenty-four Sprague-Dawley rats were randomized prospectively into a saline group (treated with normal saline, 1 ml intravenously, n = 8), an epinephrine group (treated with epinephrine, 0.04 mg/kg intravenously, n = 8) or a naloxone group (treated with naloxone, 1 mg/kg intravenously, n = 8) in a blind fashion during resuscitation after asphyxial cardiac arrest. After 5 min of untreated cardiac arrest, conventional manual CPR was started and each drug was administered at the same time.

RESULTS

The rates of restoration of spontaneous circulation (ROSC) were one of eight (12.5%), seven of eight (87.5%) and seven of eight (87.5%) in the saline, epinephrine and naloxone groups, respectively. The rates of ROSC in the epinephrine and naloxone groups were equal and significantly greater than that in the saline group (P = 0.01 and P = 0.01, respectively).

CONCLUSION

The administration of naloxone or epinephrine alone may increase the resuscitation rate, and both drugs are equally effective for CPR in a rat asphyxia model. However, the mechanism by which naloxone produces its efficacy during CPR remains unclear and further experimentation will be necessary.

Reventilation with room air or 100% oxygen after asphyxia differentially affects cerebral neuropathology in newborn pigs

AIM

To test if reventilation with room air (RA) or 100% oxygen (O2) after asphyxia would differentially affect neuronal damage in different brain areas of newborn pigs.

METHODS

Anaesthetized piglets were subjected to 10 min asphyxia (n=27) or served as time controls (n=7). Reventilation started with either RA or O2 for 1 h, and was continued with RA for an additional 1-3 h. Cortical or cerebellar blood flow was assessed with laser-Doppler flowmetry (LDF). Haematoxylin/eosin-stained sections from six brain regions were prepared for blinded neuropathological examination and scoring.

RESULTS

Asphyxia resulted in significant neuronal damage compared to time controls in all areas examined except the pons. O2 ventilation elicited greater neuronal lesions in the hippocampus and the cerebellum but smaller damage in the basal ganglia compared to RA. The assessed physiological parameters including the LDF signals were similar in both ventilation groups, except for PaO2 in the first hour of reventilation (RA 75+/-5 mmHg, O2 348+/-57 mmHg; p<0.05). Interestingly, however, reactive hyperaemia was much higher in the O2-sensitive cerebellum as compared with the cortex (1101+/-227 vs 571+/-73; p<0.05, area under the curve).

CONCLUSION

O2 toxicity after asphyxia was demonstrated in the piglet hippocampus and cerebellum but not in the cerebral cortex or basal ganglia. The observed regional differences may be associated with local haemodynamic factors.

Hypothermia and ERK activation after cardiac arrest

Mild hypothermia improves survival and neurological outcome after cardiac arrest, as well as increasing activation of the extracellular-signal-regulated kinase (ERK) in hippocampus. ERK signaling is involved in neuronal growth and survival. We tested the hypothesis that the beneficial effects of hypothermia required ERK activation. ERK activation was measured by immunoblotting with phosphorylation-specific antibodies. Rats (n = 8 per group) underwent 8 min of asphyxial cardiac arrest and were resuscitated with chest compressions, ventilation, epinephrine and bicarbonate. At 30 min after resuscitation, vehicle (50% saline:50% DMSO) or the ERK kinase inhibitor U0126 (100 microg) was infused into the lateral ventricle. Cranial temperature was kept at either 33 degrees C (hypothermia) or 37 degrees C (normothermia) between 1 and 24 h. Neurological function was assessed daily for 14 days. Surviving neurons were counted in the hippocampus. A dose of 100 mug U0126 inhibited ERK bilaterally for 12 to 24 h and decreased phosphorylation of the ERK substrates ATF-2 and CREB. As in previous studies, hypothermia improved survival, neurological and histological outcome after cardiac arrest. However, survival, neurological score and histology did not differ between U0126 and vehicle-treated rats after cardiac arrest. Therefore, a dose of U0126 sufficient to inhibit biochemical markers of ERK signaling in hippocampus does not alter the beneficial effects of hypothermia induced after resuscitation in rats and did not affect recovery of normothermia-treated rats. These results suggest that hypothermia-induced improvement in outcomes does not require ERK activation.

Duration of mechanical ventilation in life-threatening pediatric asthma: description of an acute asphyxial subgroup

OBJECTIVE

Acute asphyxial asthma (AAA) is well described in adult patients and is characterized by a sudden onset that may rapidly progress to a near-arrest state. Despite the initial severity of AAA, mechanical ventilation often restores gas exchange promptly, resulting in shorter durations of ventilation. We believe that AAA can occur in children and can lead to respiratory failure that requires mechanical ventilation. Furthermore, children with rapid-onset respiratory failure that requires intubation in the emergency department (ED) are more likely to have AAA and a shorter duration of mechanical ventilation than those intubated in the pediatric intensive care unit (PICU).

METHODS

An 11-year retrospective chart review (1991-2002) was conducted of all children who were aged 2 through 18 years and had the primary diagnosis of status asthmaticus and required mechanical ventilation.

RESULTS

During the study period, 33 (11.4%) of 290 PICU admissions for status asthmaticus required mechanical ventilation. Thirteen children presented with rapid respiratory failure en route, on arrival, or within 30 minutes of arrival to the ED versus 20 children who progressed to respiratory failure later in their ED course or in the PICU. Mean duration of mechanical ventilation was significantly shorter in the children who presented with rapid respiratory failure versus those with progressive respiratory failure (29 +/- 43 hours vs 88 +/- 72 hours). Children with rapid respiratory failure had greater improvements in ventilation and oxygenation than those with progressive respiratory failure as measured by pre- and postintubation changes in arterial carbon dioxide pressure, arterial oxygen pressure/fraction of inspired oxygen ratio, and alveolar-arterial gradient. According to site of intubation, 23 children required intubation in the ED, whereas 10 were intubated later in the PICU. Mean duration of mechanical ventilation was significantly shorter in the ED group versus the PICU group (42 +/- 63 hours vs 118 +/- 46 hours). There were significantly greater improvements in ventilation and oxygenation in the ED group versus the PICU group as measured by pre- and postintubation changes in arterial carbon dioxide pressure and arterial oxygen pressure/fraction of inspired oxygen ratio.

CONCLUSIONS

AAA occurs in children and shares characteristics seen in adult counterparts. Need for early intubation is a marker for AAA and may not represent a failure to maximize preintubation therapies. AAA represents a distinct form of life-threatening asthma and requires additional study in children.

[Usefulness of flexible bronchoscopy for aspiration of foods into the tracheobronchial trees in 2 patients with severe motor and intellectual disabilities]

Two patients with severe motor and intellectual disabilities who suffered from acute asphyxia and respiratory failure due to aspiration of foods into the tracheobronchial trees were reported. Numerous food particles were found in the tracheobronchial trees of both the patients. One patient showed recurrent atelectasis at various sites. After oral intubation, flexible bronchoscopy could successfully remove food particles from the tracheobronchial trees in both the patients without any complications. A rigid bronchoscope is usually recommended for removal of foreign bodies from the airways in children. However, it is difficult to use in patients with severe motor and intellectual disabilities, because their airway may show deformation or the aspirated foods may enter the peripheral bronchi. Our cases suggest that flexible bronchoscopy can be useful for removing foreign bodies from the tracheobronchial trees in neurologically handicapped patients for whom rigid bronchoscopy can not be applied.

Resuscitation with 100% oxygen causes intestinal glutathione oxidation and reoxygenation injury in asphyxiated newborn piglets

OBJECTIVE

To compare mesenteric blood flow, oxidative stress, and mucosal injury in piglet small intestine during hypoxemia and reoxygenation with 21%, 50%, or 100% oxygen.

SUMMARY BACKGROUND DATA

Necrotizing enterocolitis is a disease whose pathogenesis likely involves hypoxia-reoxygenation and the generation of oxygen-free radicals, which are known to cause intestinal injury. Resuscitation of asphyxiated newborns with 100% oxygen has been shown to increase oxidative stress, as measured by the glutathione redox ratio, and thus may predispose to free radical-mediated tissue injury.

METHODS

Newborn piglets subjected to severe hypoxemia for 2 hours were resuscitated with 21%, 50%, or 100% oxygen while superior mesenteric artery (SMA) flow and hemodynamic parameters were continuously measured. Small intestinal tissue samples were analyzed for histologic injury and levels of oxidized and reduced glutathione.

RESULTS

SMA blood flow decreased to 34% and mesenteric oxygen delivery decreased to 9% in hypoxemic piglets compared with sham-operated controls. With reoxygenation, SMA blood flow increased to 177%, 157%, and 145% of baseline values in piglets resuscitated with 21%, 50%, and 100% oxygen, respectively. Mesenteric oxygen delivery increased to more than 150% of baseline values in piglets resuscitated with 50% or 100% oxygen, and this correlated significantly with the degree of oxidative stress, as measured by the oxidized-to-reduced glutathione ratio. Two of eight piglets resuscitated with 100% oxygen developed gross and microscopic evidence of pneumatosis intestinalis and severe mucosal injury, while all other piglets were grossly normal.

CONCLUSIONS

Resuscitation of hypoxemic newborn piglets with 100% oxygen is associated with an increase in oxygen delivery and oxidative stress, and may be associated with the development of small intestinal hypoxia-reoxygenation injury. Resuscitation of asphyxiated newborns with lower oxygen concentrations may help to decrease the risk of necrotizing enterocolitis.

[Near asphyxiation of a neonate due to miconazole oral gel]

A 17-day-old female infant with thrush was almost asphyxiated by miconazole oral gel that had been applied to the nipples of her mother's breasts. The infant recovered after her mother had removed the gel from her mouth. Thrush is most often self-limiting and medical treatment is usually unnecessary. When treatment is indicated, miconazole oral gel or nystatin can be given. To obtain a therapeutic effect, long-term contact with the oral mucosa is needed and therefore the oral gel is viscous. Small amounts of the gel should be applied to the oral mucosa. When prescribing miconazole oral gel, instructions should be given regarding the mode of administration and the risk of respiratory tract obstruction should be pointed out.

Prognostic factors in hanging injuries

The objectives of this study were to review variable factors influencing outcomes in hanging and to identify prognostic factors related to outcomes. Forty-seven patients presented to our department. Eleven patients survived and 36 died. A significant difference in mean hanging time was observed between survivor (11.8 +/- 8.37 minutes) and nonsurvivor (50.81 +/- 61.9). In survivors, heartbeat was recognized in 63.6% at the scene and in 90.9% on arrival. Conversely, cardiopulmonary arrest (CPA) was recognized in all nonsurvivors and heartbeat was recognized on arrival in only 5.6%. Thirty-nine (83%) had a Glasgow Coma Score (GCS) of 3 on arrival. Three (7.7%) of theses 39 patients survived. In survivors, eight patients had a GCS greater than 3. A significant difference in outcome existed between patients with a GCS of 3 and those with a GCS greater than 3. Hanging time, presence of CPA at the scene and on arrival, and GCS on arrival represented prognostic factors of outcome in hanging.

Neurotensin-induced hypothermia improves neurologic outcome after hypoxic-ischemia

OBJECTIVE

External cooling is commonly used to force induction of mild hypothermia but requires equipment, has a slow onset of action, and must be prolonged to provide permanent neurologic benefits after hypoxic-ischemia. It is unknown whether the method for inducing mild hypothermia affects neurologic outcome after near-drowning. The objective of the study was to induce mild hypothermia with neurotensin analog NT77 or external cooling in a rat model of near-drowning. We hypothesize that NT77 would be more effective for improving neurologic outcome than external cooling of the same duration.

DESIGN

Rats were randomized to a normothermic control, neurotensin-induced hypothermia, brief external cooling, or prolonged external cooling group after asphyxial cardiac arrest.

SETTING

Laboratory investigation.

SUBJECTS

Forty-eight rats.

INTERVENTIONS

Mild hypothermia was induced by external cooling for 4 hrs (brief external cooling) or 24 hrs (prolonged external cooling) or by neurotensin-induced hypothermia administration 30 mins after asphyxial cardiac arrest in rats.

MEASUREMENTS

Outcome was assessed by a neurologic deficit score, the Morris water maze, and CA1 hippocampus histology 15 days after resuscitation.

MAIN RESULTS

Neurologic deficit score at 72 hrs after asphyxial cardiac arrest was lower with neurotensin-induced hypothermia (score, 0) and prolonged external cooling (score, 0) vs. normothermic control (score, 20) and brief external cooling (score, 18; p <.05). Latency time in the Morris water maze 15 days after asphyxial cardiac arrest was decreased with neurotensin-induced hypothermia (14+/-11 secs) and prolonged external cooling (18+/-9 secs) vs. normothermic control (74+/-17 secs) and brief external cooling (78+/-18 secs, p <.05). There was less ischemic neuronal damage with neurotensin-induced hypothermia (28+/-24%) and prolonged external cooling (21+/-14%) vs. normothermic control (61+/-32%) and brief external cooling (51+/-32%).

CONCLUSIONS

Neurotensin-induced hypothermia improved neurologic outcome after asphyxial cardiac arrest in rats vs. brief external cooling but was comparable to prolonged external cooling.

Syndrome d’asphyxie traumatique ou syndrome de Perthes. À propos de six cas

Perthe's syndrome or traumatic asphyxia is a clinical syndrome associating cervicofacial cyanosis, petechia and subconjonctival hemorrhage to neurological symptoms. This syndrome appears after severe and transient compressive blunt chest injury. A Valsalva maneuver is necessary before thoracic compression for the development of this syndrome. The treatment includes rapid chest decompression and cardiopulmonary resuscitation. The prognosis is good but a prolonged thoracic compression could lead to cerebral anoxia and neurological sequelae. We report six cases of Perthe's syndrome most of them resulting from thoracic compression after road traffic accidents. All of them made a good prognosis.

Comparison of isoflurane and propofol–fentanyl anaesthesia in a swine model of asphyxia

BACKGROUND

There have been few studies comparing the response to asphyxia and the effectiveness of typical cardiopulmonary resuscitation (CPR) using exogenous epinephrine administration and manual closed-chest compression between total intravenous anaesthesia (TIVA) and inhalational anaesthesia.

METHODS

Twenty pigs were randomly assigned to two study groups anaesthetized using either 2% end-tidal isoflurane (n=10) or propofol (12 mg x kg(-1) h(-1))-fentanyl (50 microg x kg(-1)) (n=10). Asphyxia was induced by clamping the tracheal tube until the mean arterial pressure (MAP) decreased to 40% of the baseline value (40% MAP time). The tracheal tube was declamped at that point, and CPR was performed. Haemodynamic parameters and blood samples were obtained before the induction of asphyxia, at 1-min intervals during asphyxia, and 1, 2, 3, 5, 10, 30 and 60 min after asphyxia.

RESULTS

TIVA maintained the MAP against hypoxia-hypercapnia stress significantly longer than isoflurane anaesthesia (mean (SD) 40% MAP time 498 (95) and 378 (104) s respectively). In all animals in the isoflurane group, spontaneous circulation returned within 1 min of the start of CPR. In six of the TIVA animals, spontaneous circulation returned for 220 (121) s; spontaneous circulation did not return within 5 min in the remaining four animals.

CONCLUSIONS

Although TIVA is less prone than isoflurane anaesthesia to primary cardiovascular depression leading to asphyxia, TIVA is associated with reduced effectiveness of CPR in which resuscitation because of asphyxic haemodynamic depression occurs.

Hypothermia for 24 hours after asphyxic cardiac arrest in piglets provides striatal neuroprotection that is sustained 10 days after rewarming

The neuroprotective effect of hypothermia instituted after resuscitation from asphyxic cardiac arrest has not been studied in immature brain, particularly in a large animal model with recovery periods greater than 4 d. Moreover, protection from severe hypoxia seen with 3 h of hypothermia was reported to be lost when hypothermic duration was extended to 24 h in unsedated piglets, in contrast to the neuroprotection reported by 72 h of intrauterine head cooling in fetal sheep. Piglets (5-7 postnatal days) were subjected to asphyxic cardiac arrest followed by 24 h of either hypothermia (34 degrees C) or normothermia (38.5-39 degrees C). Comparisons were made with normothermic and hypothermic surgical sham animals without asphyxia. All of these groups were sedated, paralyzed, and mechanically ventilated for the first 24 h to prevent shivering and possible depletion of glucose stores. Hypothermia per se did not cause remarkable structural abnormalities. Ischemic damage was evaluated in putamen at 1 d of recovery without rewarming and at 11 d (10 d +/- SD after rewarming). Ischemic cytopathology affected 60 +/- 12% of neurons in putamen of normothermic animals compared with 9 +/- 6% in hypothermic animals at 1 d of recovery without rewarming. At 11 d of recovery from hypoxia-ischemia, the density of viable neurons (neuron profiles/mm2) in putamen was markedly reduced in normothermic animals (81 +/- 40) compared with hypothermic animals (287 +/- 22), which was the same as in sham normothermic (271 +/- 21), sham hypothermic (288 +/- 46) and naïve animals (307 +/- 51). These data demonstrate that 24 h of hypothermia at 34 degrees C with sedation and muscle relaxation after asphyxic cardiac arrest prevents necrotic striatal neuronal cell death in immature brain before rewarming, and that the effect is sustained at 11 d after injury without deleterious side effects.

Long term production of reactive oxygen species during perinatal asphyxia in the rat central nervous system: effects of hypothermia

The formation of oxygen-derived free radicals in hypoxic and ischemic/reperfused brains has been proposed as an important step that links brain injury to neuronal death. Previously, we have demonstrated that reactive oxygen species (ROS) production was significantly increased in rat neostriatum during acute perinatal asphyxia (PA) in pups. In this article, we have studied the time course of ROS production in the neostriatum and neocortex of adult rats subjected to PA using electron spin resonance spectrometry (ESR) in order to record ROS production. Further more, we analyzed the actions of hypothermia on ROS release in pups and adult rats. We used for this study 6-month-old rats that suffered sub-severe and severe PA when they were pups. The most significant production of ROS was detected either in the neostriatum or neocortex at 19 and 20 min of PA. Hypothermia during 20 and 100 min at 15 degrees C prevented ROS formation either in pups and adult rats. These data further support the concept that free radicals may contribute to the brain injury alterations and that hypothermia can prevent long-term sequelae induced by PA.

Clinical trials of treatments after perinatal asphyxia

Following critical hypoxia-ischemia during labor and delivery, there is a window of therapeutic opportunity during hypoxic-ischemic encephalopathy. Meta-analysis of three randomized trials of prophylactic barbiturate therapy for neonatal hypoxic-ischemic encephalopathy showed no significant effect on death or disability. One randomized trial of allopurinol showed short-term benefits but was too small to test death or disability. No adequate trials of dexamethasone, calcium channel blockers, or magnesium sulphate have yet been completed, but pilot studies in infants have shown the cardiovascular risks of magnesium sulphate and calcium channel blockers. There is considerable evidence from animal studies that posthypoxic mild hypothermia reduces brain injury. One small randomized trial of mild hypothermia found no adverse effects but was too small to examine death or disability. One large randomized trial of selective head cooling has finished recruitment and a number of large trials of systemic mild hypothermia are ongoing. As time is critical with post-hypoxic interventions, the delay involved in obtaining informed parental consent for such trials might obscure a clinically important therapeutic effect.

Prognostic outcome indicators following hanging injuries

Hanging as a method of attempting suicide is increasing in incidence. A retrospective review of victims of hanging injuries presenting to our institution over a 5-year period was performed. Forty-two cases were reviewed. Drug and/or alcohol ingestion was identified in 70% of cases. There were no cervical spine injuries identified, although two unexpected thoracic spine fractures were found. There was an 88% survival rate, with a low incidence (5%) of poor neurological outcome. The Glasgow Coma Score at scene or on arrival at hospital was found to be a prognostic indicator. Victims without spontaneous cardiac output at scene did not survive, even if cardiopulmonary resuscitation was successful initially.

S100B protein is increased in asphyxiated term infants developing intraventricular hemorrhage

OBJECTIVE

To establish whether S100B protein may be useful in the early detection of intraventricular hemorrhage in asphyxiated term infants.

DESIGN

Case-control study.

PATIENTS

Twenty full-term newborns with intraventricular hemorrhage, 20 asphyxiated infants without intraventricular hemorrhage, and 80 normal newborns.

INTERVENTIONS

Routine laboratory variables and neurologic patterns were assessed at birth after 12 and 72 hrs. Ultrasound imaging and middle cerebral artery Doppler velocimetry pulsatility index were recorded at 12 and 72 hrs after birth. S100B protein blood concentrations were determined at 12 hrs.

MEASUREMENTS AND MAIN RESULTS

S100B protein levels were significantly higher in samples collected from newborns who developed intraventricular hemorrhage (1.87 +/- 0.60 microg/L) than from those who did not develop intraventricular hemorrhage (0.72 +/- 0.39 microg/L) or from normal infants (0.66 +/- 0.31 microg/L). Multiple logistic regression analysis showed a significant correlation between circulating S100B protein concentrations and the occurrence of intraventricular hemorrhage.

CONCLUSIONS

This study suggests that elevated S100B protein represents a useful tool for the early detection of intraventricular hemorrhage in the postasphyxia period when clinical examination and cerebral ultrasound might still be silent.