Certification tests currently employed by some industrialized nations to certify respirators require that when challenged with air flow at a constant suction head of 25 mmH2O, the leakage into the facepiece from the exhalation valve(s) should not exceed 30 ml min(-1). However, the test alone might not reflect the leakage rate under different levels of vacuum. To study the characteristics of leakage through exhalation valves, a leakage meter was built to measure the leakage rate of four brands of exhalation valves. Seven valves of each brand were tested for leakage rate at pressure drops ranging from 15 to 45 mmH2O (or extended to 75 mmH2O for some valves). Two types of leaks, i.e. fiber insertion and arch dent on the valve seat, were used to investigate the effect of leak shape on the characteristic leak flow as a function of pressure drop. A leakage data point represented a mean value of five measurements. The results showed that the leakage rate could increase or decrease with increasing pressure drop inside the respirators, indicating that the current method of conducting leakage tests, at a constant suction head of 25 mmH2O, does not guarantee better protection than when the respirators are used at a lower suction head. Moreover, based on the sample valves tested in this study, it was found that valve leakage was mostly caused by defects in the valve seats. Both fiber-insertion and arch-dent leaks had either increasing or decreasing characteristic curves, depending on the size of the leak and the material of the valve membrane. (+info)
Neonatal resuscitation 3: manometer use in a model of face mask ventilation.
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BACKGROUND: Adequate ventilation is the key to successful neonatal resuscitation. Positive pressure ventilation (PPV) is initiated with manual ventilation devices via face masks. These devices may be used with a manometer to measure airway pressures delivered. The expiratory tidal volume measured at the mask (V(TE(mask))) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. AIM: To assess the effect of viewing a manometer on the peak inspiratory pressures used, the volume delivered, and leakage from the face mask during PPV with two manual ventilation devices in a model of neonatal resuscitation. METHODS: Participants gave PPV to a modified resuscitation mannequin using a Laerdal infant resuscitator and a Neopuff infant resuscitator at specified pressures ensuring adequate chest wall excursion. Each participant gave PPV to the mannequin with each device twice, viewing the manometer on one occasion and unable to see the manometer on the other. Data from participants were averaged for each device used with the manometer and without the manometer separately. RESULTS: A total of 7767 inflations delivered by the 18 participants were recorded and analysed. Peak inspiratory pressures delivered were lower with the Laerdal device. There were no differences in leakage from the face mask or volumes delivered. Whether or not the manometer was visible made no difference to any measured variable. CONCLUSIONS: Viewing a manometer during PPV in this model of neonatal resuscitation does not affect the airway pressure or tidal volumes delivered or the degree of leakage from the face mask. (+info)
Neonatal resuscitation 2: an evaluation of manual ventilation devices and face masks.
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BACKGROUND: The key to successful neonatal resuscitation is effective ventilation. Little evidence exists to guide clinicians in their choice of manual ventilation device or face mask. The expiratory tidal volume measured at the mask (V(TE(mask))) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. AIM: To compare the efficacy of (a) the Laerdal infant resuscitator and the Neopuff infant resuscitator, used with (b) round and anatomically shaped masks in a model of neonatal resuscitation. METHODS: Thirty four participants gave positive pressure ventilation to a mannequin at specified pressures with each of the four device-mask combinations. Flow, inspiratory tidal volume at the face mask (V(TI(mask))), V(TE(mask)), and airway pressure were recorded. Leakage from the mask was calculated from V(TI(mask)) and V(TE(mask)). RESULTS: A total of 10,780 inflations were recorded and analysed. Peak inspiratory pressure targets were achieved equally with the Laerdal and Neopuff resuscitators. Positive end expiratory pressure was delivered with the Neopuff but not the Laerdal device. Despite similar peak pressures, V(TE(mask)) varied widely. Mask leakage was large for each combination of device and mask. There were no differences between the masks. CONCLUSION: During face mask ventilation of a neonatal resuscitation mannequin, there are large leaks around the face mask. Airway pressure is a poor proxy for volume delivered during positive pressure ventilation through a mask. (+info)
Neonatal resuscitation 1: a model to measure inspired and expired tidal volumes and assess leakage at the face mask.
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BACKGROUND: Neonatal resuscitation is a common and important intervention, and adequate ventilation is the key to success. In the delivery room, positive pressure ventilation is given with manual ventilation devices using face masks. Mannequins are widely used to teach and practise this technique. During both simulated and real neonatal resuscitation, chest excursion is used to assess tidal volume delivery, and leakage from the mask is not measured. OBJECTIVE: To describe a system that allows measurement of mask leakage and estimation of tidal volume delivery. METHODS: Respiratory function monitors, a modified resuscitation mannequin, and a computer were used to measure leakage from the mask and to assess tidal volume delivery in a model of neonatal resuscitation. RESULTS: The volume of gas passing through a flow sensor was measured at the face mask. This was a good estimate of the tidal volume entering and leaving the lung in this model. Gas leakage between the mask and mannequin was also measured. This occurred principally during inflation, although gas leakage during deflation was seen when the total leakage was large. A volume of gas that distended the mask but did not enter the lung was also measured. CONCLUSION: This system can be used to assess the effectiveness of positive pressure ventilation given using a face mask during simulated neonatal resuscitation. It could be useful for teaching neonatal resuscitation and assessing ventilation through a face mask. (+info)
Meaningful workplace protection factor measurement: experimental protocols and data treatment.
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Workplace performance measurement of respiratory protective equipment (RPE) is fundamental to the understanding of how well wearers are protected. It forms the basis for guidance on which the selection of appropriate equipment is based. However, the measurement of this performance is open to many sources of interference and inaccuracy, reducing the value and relevance of the results, and is most difficult for devices providing the highest levels of protection. In this paper, a method for critically assessing collected workplace protection factor (WPF) data is validated. This method rejects unreliable data, using criteria based on the detection limits of the analytical measurement system. An iterative approach is also described which arrives at a supportable estimate of given non-parametric percentiles of the distribution of measured WPFs [such as the fifth percentile, conventionally taken to be the assigned protection factor (APF)]. Further pragmatic criteria, based on a combination of experimental experience and consideration from first principles, are suggested as the basis for any future studies of RPE performance. These will maximize the chances of valid measurements being made, and also provide insight into the level of confidence which can be placed on any of the results. A consequence of these criteria is that typical working environments and measurement methods are incapable of generating WPF data which can be considered reliable. (+info)
Incidence of nasal trauma associated with nasal prong versus nasal mask during continuous positive airway pressure treatment in very low birthweight infants: a randomised control study.
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OBJECTIVE: To compare the incidence of nasal trauma associated with the use of prong or mask during nasal continuous positive airway pressure (nCPAP) support in very low birthweight (<1501 g) infants. DESIGN: Randomised controlled clinical trial. SETTING: Tertiary care university hospital, Department of Paediatrics, Kuala Lumpur, Malaysia. METHODS: All very low birthweight infants admitted to the neonatal intensive care unit between July 2001 and December 2003 who received nCPAP through the Infant Flow Driver were randomised to the use of either nasal prong or mask. The nasal cavity of these infants was inspected daily during the first week and then weekly until they were weaned off nCPAP. RESULTS: Of the 89 infants recruited, 41 were randomised to the mask group and 48 to the prong group. There was no significant difference in the incidence of nasal trauma between the two groups (p = 0.5). The primary site of trauma was at the junction between the nasal septum and the philtrum in infants in the mask group and the walls of the nasal septum in the prong group. Logistic regression analysis showed that duration of nCPAP was the only significant risk factor associated with development of nasal injury, after birth weight, gestational age, and nasal device used had been controlled for (adjusted odds ratio 1.04; 95% confidence interval 1.01 to 1.07; p = 0.003). CONCLUSION: Irrespective of the type of nasal device used, nasal trauma is common during nCPAP treatment, which should therefore be terminated as soon as possible. (+info)
Compliance with infection control programs in private dental clinics in Jordan.
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The aim of this study was to assess the compliance of general dental practitioners (GDPs) in the private sector in North Jordan with infection control measures. A pilot-tested questionnaire about infection control measures was distributed in March 2004 to 120 private practices. The response rate was 91.66 percent. About 77 percent of dentists usually ask their patients about medical history, 36 percent were vaccinated against hepatitis B, 81.8 percent wear and change gloves during treatment and between patients, and 54.5 percent wear and change masks during treatment and between patients. Most dental practitioners (95.4 percent) reported that they changed extraction instruments and burs between patients. All dental practitioners reported that they changed saliva ejectors between patients, but only 41.8 percent changed handpieces between patients. Approximately 63 percent (69/110) used autoclaves for sterilization, 47.3 percent (52/110) used plastic bags to wrap sterilized instruments, and only 18 percent (20/110) disinfected impressions before sending them to dental labs. Fourteen percent used rubber dams in their clinics, and only 31.8 percent had special containers for sharps disposal. Based on these responses, approximately 14 percent of general dentists in this sample were considered to be compliant with an inventory of recommended infection control measures. In Jordan, there is a great need to provide formal and obligatory infection control courses and guidelines for private dentists by the Ministry of Health and the dental association in addition to distribution of standard infection control manuals that incorporate current infection control recommendations. (+info)
Effectiveness of mask and helmet interfaces to deliver noninvasive ventilation in a human model of resistive breathing.
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The helmet, a transparent latex-free polyvinyl chloride cylinder linked by a metallic ring to a soft collar that seals the helmet around the neck, has been recently proposed as an effective alternative to conventional face mask to deliver pressure support ventilation (PSV) during noninvasive ventilation in patients with acute respiratory failure. We tested the hypothesis that mechanical characteristics of the helmet (large internal volume and high compliance) might impair patient-ventilator interactions compared with standard face mask. Breathing pattern, CO(2) clearance, indexes of inspiratory muscle effort and patient-ventilator asynchrony, and dyspnea were measured at different levels of PSV delivered by face mask and helmet in six healthy volunteers before (load-off) and after (load-on) application of a linear resistor. During load-off, no differences in breathing pattern and inspiratory muscle effort were found. During load-on, the use of helmet to deliver pressure support increased inspiratory muscle effort and patient-ventilator asynchrony, worsened CO(2) clearance, and increased dyspnea compared with standard face mask. Autocycled breaths accounted for 12 and 25% of the total minute ventilation and for 10 and 23% of the total inspiratory muscle effort during mask and helmet PSV, respectively. We conclude that PSV delivered by helmet interface is less effective in unloading inspiratory muscles compared with PSV delivered by standard face mask. Other ventilatory assist modes should be tested to exploit to the most the potential benefits offered by the helmet. (+info)