Threshold levels of maternal nicotine impairing protective responses of newborn rats to intermittent hypoxia.
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Experiments were carried out to determine the threshold level of maternal nicotine that impairs protective responses of rat pups to hypoxia. From days 6 or 7 of gestation, pregnant rats received either vehicle or nicotine (1.50, 3.00, or 6.00 mg of nicotine tartrate. kg body wt(-1).day(-1)) or vehicle continuously via a subcutaneous osmotic minipump. On postnatal days 5 or 6, pups were exposed to a single period of hypoxia produced by breathing an anoxic gas mixture (97% N(2) or 3% CO(2)) and their time to last gasp was determined, or they were exposed to intermittent hypoxia and their ability to autoresuscitate from hypoxic-induced primary apnea was determined. Perinatal exposure to nicotine did not alter the time to last gasp or the total number of gasps when the pups were exposed to a single period of hypoxia. The number of successful autoresuscitations on repeated exposure to hypoxia was, however, decreased in pups whose dams had received either 3.00 or 6.00 mg of nicotine tartrate/kg body wt; these dosage regimens produced maternal serum nicotine concentrations of 19 +/- 6 and 35 +/- 8 ng/ml, respectively. Thus our experiments define the threshold level of maternal nicotine that significantly impairs protective responses of 5- to 6-day-old rat pups to intermittent hypoxia such as may occur in human infants during episodes of prolonged sleep apnea or positional asphyxia. (+info)
Emergency airway management by non-anaesthesia house officers--a comparison of three strategies.
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OBJECTIVES: The purpose of this study was to determine effects of different airway devices and tidal volumes on lung ventilation and gastric inflation in an unprotected airway. METHODS: Thirty one non-anaesthesia house officers volunteered for the study, and ventilated a bench model simulating an unintubated respiratory arrest patient with bag-valve-facemask, laryngeal mask airway, and combitube using paediatric and adult self inflating bags. RESULTS: The paediatric versus adult self inflating bag resulted with the laryngeal mask airway and combitube in significantly (p<0.001) lower mean (SEM) lung tidal volumes (376 (30) v 653 (47) ml, and 368 (28) v 727 (53) ml, respectively). Gastric inflation was zero with the combitube; and 0 (0) v 8 (3) ml with the laryngeal mask airway with low versus large tidal volumes. The paediatric versus adult self inflating bag with the bag-valve-facemask resulted in comparable lung tidal volumes (245 (19) v 271 (33) ml; p=NS); but significantly (p<0.001) lower gastric tidal volume (149 (11) v 272 (24) ml). CONCLUSIONS: The paediatric self inflating bag may be an option to reduce the risk of gastric inflation when using the laryngeal mask airway, and especially, the bag-valve-facemask. Both the laryngeal mask airway and combitube proved to be valid alternatives for the bag-valve-facemask in this experimental model. (+info)
Cardiac tamponade and central venous catheters.
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An analysis of the reports on 16 patients who developed cardiac tamponade, complicating the use of central venous catheters, showed that 14 died. The two survivors were treated by removal of the catheter and needle aspiration of the pericardial fluid. Some patients complained of warning symptoms such as nausea, pain, and dyspnoea, and the combination of tachycardia, hypotension, and raised venous pressure was common. We suggest that awareness of the hazard, radiographic visualization of the catheter tip, and expeditious treatment would reduce the mortality. (+info)
Changes in paediatric resuscitation knowledge among doctors.
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AIMS: To investigate whether paediatricians have improved their resuscitation knowledge since 1992, and whether those who have attended a paediatric resuscitation course have greater knowledge than those who have not. METHODS: Telephone survey of 94 resident paediatricians admitting emergency cases. Questions on clinical scenarios were asked and adherence to internationally agreed guidelines in answering was determined. RESULTS: There were significantly more correct answers to 9/10 questions in 1999 compared to 1992. The 1999 doctors who had attended a course scored significantly better in 3/10 questions and achieved a higher total score (5.43 versus 4.55). CONCLUSIONS: Knowledge has improved since 1992; this has been over the period in which paediatric resuscitation courses were introduced. In 1999 those who had been on a course were more knowledgeable than those who had not. (+info)
The changes in delivered oxygen fractions using laerdal resuscitator bag with different types of reservoir.
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One of the disadvantages of the Laerdal resuscitator bag is that it does not deliver a high concentration of oxygen without a reservoir and an appropriate technique of ventilation. With a specific device that is able to compress a resuscitator bag mechanically at a regular volume, ventilator rate, and speed, we evaluated the effects of various factors (the tidal volume, the ventilator rate, the oxygen flow rate, the type of reservoir) of the Laerdal resuscitator bag during positive pressure ventilation that affect the delivered oxygen fraction (FDO2) and also whether 250 mL and 500 mL corrugated tubes could be used as substitutes for the reservoir bag. The 250 mL corrugated tube increased the FDO2 to over 96% with an oxygen flow rate of 15 L/min. The 500 mL corrugated tube increased the FDO2 to over 96% with an oxygen flow rate of 10 L/min regardless of the ventilator rate at a fixed tidal volume of 500 mL. At the identical fixed tidal volume of 500 mL, the 1,600 mL reservoir bag increased the FDO2 to over 92% with an oxygen flow rate of 5 L/min and to over 96% at 7.5 L/min regardless of the ventilator rate. We concluded that the FDO2 of the Laerdal resuscitator bag depends on various factors such as tidal volume, ventilator rate, oxygen flow rate, and type of reservoir and both the 250 mL and 500 mL corrugated tubes can be used as substitutes. (+info)
Hemorrhage-induced alpha-adrenergic signaling results in myocardial TNF-alpha expression and contractile dysfunction.
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Hemorrhagic shock (HS), secondary to major blood loss, frequently precedes multiple organ dysfunction and is accompanied by a surge in circulating catecholamine levels. Expression of the cardiodepressant cytokine, tumor necrosis factor-alpha (TNF-alpha), has been observed in the heart after HS and resuscitation (HS/R) and alpha(1)-adrenergic blockade prevented translocation of the nuclear transcription factor, NF-kappa B, to the nucleus. We hypothesized that alpha(1)-adrenergic stimulation induces myocardial TNF-alpha expression, which results in depressed cardiac function after HS/R. The role of alpha(1)-adrenergic stimulation in myocardial TNF-alpha expression and depressed cardiac function after HS/R was assessed by treatment with the alpha(1)-adrenergic inhibitor, prazosin hydrochloride (1 mg/kg ip), for 1 h before the onset of hemorrhage. In addition, TNF-alpha was neutralized with a specific antibody (600 microl/kg iv) 5 min before hemorrhage. HS was induced by the withdrawal of blood to a mean blood pressure of 50 mmHg for 1 h. Contractile function was measured with the use of a Langendorff apparatus 2 h after the end of HS. HS/R led to significant decreases in left ventricular developed tension and in the maximal rate of pressure increase over time during both contraction and relaxation. Myocardial expression of TNF-alpha measured by enzyme-linked immunosorbent assay increased significantly after 30 min of hemorrhage and peaked after 60 min of HS and 45 min of resuscitation. Depression in cardiac function after HS/R was reversed by 85% in hearts from rats treated with a TNF-alpha neutralizing antibody and by 90% in hearts from rats treated with prazosin hydrochloride. We conclude that HS activates a alpha(1)-adrenergic pathway, resulting in TNF-alpha expression in the heart and depressed myocardial contractile function. (+info)
Advances in fluid resuscitation of hemorrhagic shock.
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The optimal fluid for resuscitation in hemorrhagic shock would combine the volume expansion and oxygen-carrying capacity of blood without the need for cross-matching or the risk of disease transmission. Although the ideal fluid has yet to be discovered, current options are discussed in this review, including crystalloids, colloids, blood and blood substitutes. The future role of blood substitutes is not yet defined, but the potential advantages in trauma or elective surgery may prove to be enormous. (+info)
A survey of the perceived quality of patient handover by ambulance staff in the resuscitation room.
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OBJECTIVES: The aim of this study was to examine the quality of handover of patients in the resuscitation room by describing the current perceptions of medical and ambulance staff. METHODS: This was a descriptive survey using two anonymous questionnaires to gauge current opinion, one designed for medical staff and the other for ambulance staff. Questionnaires were distributed to medical staff in two teaching hospital accident and emergency (A&E) departments and ambulance personnel in the Tayside region of Scotland. RESULTS: 30 medical and 67 ambulance staff completed questionnaires. Some 19.4% of ambulance staff received formal training in giving a handover, 83% of the remaining felt there was a need for training. Medical staff conveyed their belief that handovers were very variable between crews and that they did not feel radio reports were well structured. Ambulance crews felt that medical staff did not pay attention to their handovers. Ambulance staff seemed satisfied with the quality of their handovers, although medical staff were less positive particularly in the context of self poisoning and chest pain. Both seem to be least confident with regards to the handover of paediatric emergencies. Medical staff were generally less satisfied with the reporting of vital signs than the history provided. CONCLUSIONS: Despite a generally positive perception of handovers there may be some room for improvement, in particular in the area of medical emergencies. Ambulance staff training should produce a structure for the handover that is recognisable to medical staff. The aim being a smooth and efficient transfer from prehospital agencies to A&E staff. (+info)