Resuscitation
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Comparative Study
Tracheal epinephrine or norepinephrine preceded by beta blockade in a dog model. Can beta blockade bestow any benefits?
Tracheal epinephrine (adrenaline) has been associated with two major deletorious side effects: increased heart rate (HR) and an initial decrease of blood pressure (BP). This prospective randomized animal study compared the haemodynamic responses to tracheally administered epinephrine or norepinephrine (nor adrenaline) alone versus each after pretreatment with propranolol for ameliorating those two untoward effects associated with epinephrine administration. Five anaesthetized mongrel dogs underwent 25 experiments of tracheal epinephrine or norepinephrine (0.02 mg/kg diluted with normal saline to 5 ml total volume) with or without an I/V non-selective beta-blocker (propranolol 0.1 mg/kg) pretreatment, and served as their own controls. ⋯ While both epinephrine or norepinephrine after pretreatment with propranolol produced a significant increase in both diastolic (from 106 to 166 mmHg and from 118 to 169 mmHg, respectively) (P<0.01) and mean BP (from 122 to 183 mmHg and from 133 to 188 mmHg, respectively) (P<0.01), only propranolol-pretreated tracheal epinephrine yielded a significant decrease in HR (from 52 to 33/m, P=0.002). Pretreatment with a beta-blocker protected against the deleterious tachycardia associated with epinephrine or norepinephrine and, by doing so, may improve the myocardial oxygen supply-and-demand balance. At the same time, the pretreatment augmented the relatively mild diastolic BP increase associated with the beta-adrenergic effect of epinephrine.
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Acidosis may contribute to brain injury from asphyxia, but its role is unclear. In order to evaluate the association between brain acidosis and cerebral injury, we subjected piglets to hypoxia and hypotension (HYP-HOTN) or hypoxia alone (HYP) to inflict varying amounts of brain damage. We hypothesized that piglets with a more severe brain injury would have a lower brain pH. ⋯ The time needed for brain pH to recover after asphyxia, but not its severity, was associated with the amount of brain injury. Further study is warranted to determine whether immediate restoration of brain pH will reduce brain damage.
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Comparative Study
Ventilation performance of a mixed group of operators using a new rescue breathing device-the glossopalatinal tube.
We studied how effectively a mixed group of helpers could ventilate a manikin with a new rescue breathing device after a short period of instruction. The device consists of a mouthcap, a "glossopalatinal tube" (GPT) reaching between tongue and palate and a connector for a bag, ventilator or the rescuers mouth. Rather than reaching behind the tongue like an oropharyngeal airway (OP), it is able to scoop the tongue off the posterior pharyngeal wall when tilted by the rescuer. It was compared with a conventional face mask with an OP. ⋯ Mean V(t) with the OP plus mask amounted to 463 (230-688 ml), with GPT to 426 (243-610 ml) (median [10-90% percentiles]) (P=0.047). No differences were observed with respect to the time a S(aO(2))> or =90% was maintained (OP plus mask: 255 (139-266 s), GPT: 255 (90-269 s)) or the grades for fatigue (OP plus mask: 58% of VAS, GPT: 48% of VAS, median) and difficulty (OP plus mask: 16% of VAS, GPT: 21% of VAS). Performance and grades were scattered over a wide range. Success with the two devices was correlated, but the subjects judgement tended to diverge. The GPT is an easy to learn alternative to conventional devices and might be helpful in clinical emergencies, including situations of unexpectedly difficult ventilation.