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PubMed1997

Computerized ventilator data selection: artifact rejection and data reduction.

OBJECTIVE: To determine acceptable strategies for automated data acquisition and artifact rejection from computerized ventilators using the Medical Information Bus. DESIGN: Medical practitioners were surveyed to establish 'clinically important' ventilator events. A prospective study involving frequent data collection from ventilators was also conducted. SUBJECTS: Data from 10 adult patients were collected every 10 seconds from a Puritan Bennett 7200A ventilator for a total of 617.1 hours. INTERVENTIONS: Twelve different computerized data selection and artifact algorithms were tested and evaluated. MEASUREMENTS AND MAIN RESULTS: Data derived from 12 data selection algorithms were compared with each other and with data manually charted by respiratory therapists into a computerized charting system. Ventilator setting data collected by the algorithms, such as FIO2, reduced the amount of data collected to about 25% compared to manually charted data. The amount of data collected for measured parameters, such as tidal volume, from the ventilator had large variability and many artifacts. Automated data capture and selection generally increased the amount of data collected compared to manual charting, for example for the 3 minute median the increase was a modest 1.2 times. CONCLUSION: Computerized methods for collecting ventilator setting data were relatively straightforward and more-efficient than manual methods. However, the method for automated selection and presentation of observed measured parameters is much more difficult. Based on the findings and analysis presented here, the authors recommend recording ventilator setting data after they have existed for three minutes and measured parameters using a three minute median data selection strategy. Such an algorithm rejected most artifacts, required minimal computational time, had minimal time-delay, and provided clinically acceptable data acquisition. The results presented here are but a starting point in developing automated ventilator data selection strategies.

Adult↗
PubMed2003

Effects of the flow waveform method of triggering and cycling on patient-ventilator interaction during pressure support.

OBJECTIVE: To examine patient-ventilator interaction during pressure support ventilation in critically ill patients when they were ventilated: (1) by a new system (Vision, Respironics) which uses the flow waveform as a method of triggering and cycling; and (2) by a new generation ventilator (Evita 4, Drager) which uses the traditional flow triggering (2 l/min) and cycling criterion (25% of peak flow). DESIGN: Prospective clinical and bench study. METHODS: Twelve mechanically ventilated patients were studied at three levels of pressure support, applied randomly with both ventilators. The two systems of triggering were further studied at controlled levels of dynamic hyperinflation and respiratory drive using an active lung model. RESULTS: Patients' breathing patterns, respiratory effort, and arterial blood gases were not affected by the type of ventilator. The flow waveform method of triggering was more sensitive to patient effort than the flow triggering, resulting in less ineffective effort but a greater number of auto-triggerings. At controlled levels of dynamic hyperinflation and inspiratory effort the simulated patient effort needed to trigger the ventilator was considerably less with the flow waveform method of triggering than that with the flow triggering. The flow waveform method of cycling resulted in mechanical breaths with similar characteristics to those that used the traditional flow criterion of breath termination. CONCLUSIONS: We conclude that the flow waveform method of triggering improves the ventilator function and decreases the patient effort during the triggering phase. This system is highly sensitive, but under certain circumstances may be unstable.

Adult↗
PubMed2003

Low tidal volume ventilation induces proinflammatory and profibrogenic response in lungs of rats.

OBJECTIVE: We examined whether mechanical ventilation with low tidal volume induces polymorphonuclear infiltration and proinflammatory and profibrogenic responses in rat lungs compared dependent and nondependent lung region to expression of interleukin-1beta (IL-1beta) and alpha-1 procollagen III (PC III) mRNA. DESIGN: An experimental, randomized and controlled protocol with previously normal rats. INTERVENTIONS: Three groups of ten animals were studied. Two groups were ventilated (FIO2=0.3) in supine position for 1 h without positive end expiratory pressure, one group with a low tidal volume (6 ml/kg), and the other with a high tidal volume (24 ml/kg). In the third group animals were kept in spontaneous ventilation for 1 h. MEASUREMENTS AND RESULTS: After ventilation the right lung was used to quantify polymorphonuclear infiltration. The left lung was divided into dependent and nondependent regions, and expression of IL-1beta and PC III mRNA was quantified by northern blot analysis. The group ventilated with low tidal volume had greater polymorphonuclear infiltration IL-1beta and PC III mRNA expression than the nonventilated group. Similar results were observed with high tidal volumes. There was no difference between low and high tidal volume ventilation. Expression levels of IL-1beta and PC III mRNA were higher in the nondependent region of ventilated groups and equal in the nonventilated group. CONCLUSIONS: Even a low tidal volume mode of mechanical ventilation induces proinflammatory and profibrogenic response, with a nondependent predominance for IL-1beta and PC III mRNA expression in supine, ventilated, previously normal rats.

Animals↗
PubMed2004

The effect of back-up rate during non-invasive ventilation in young patients with cystic fibrosis.

OBJECTIVE: The aim of the study was to evaluate the effect of the back-up rate on respiratory effort during non-invasive mechanical ventilation. DESIGN: An in vitro study evaluated the inspiratory trigger in seven domiciliary ventilators. Then, a prospective, randomized, crossover trial compared the effect on respiratory effort of three different back-up rates during pressure support (PS) and assist-control/volume-targeted (AC/VT) ventilation. SETTING: A research unit and a tertiary referral pediatric center. PATIENTS: Ten patients with cystic fibrosis (CF). INTERVENTIONS: During the in vivo study, the back-up rate was progressively increased to the maximum that patients could tolerate (Fmax) and respiratory effort, as judged by pressure/time product of the diaphragm (PTPdi/min), was compared between the two ventilatory modes. RESULTS: Differences were observed between trigger pressure, trigger time delay, trigger pressure/time product and the slope between flow and pressure in the seven ventilators. PS and AC/VT ventilation were associated with a decrease in respiratory effort (PTPdi/min was 518+/-172, 271+/-119 and 291+/-138 cmH(2)O. s(-1). min(-1), for spontaneous breathing, PS and AC/VT ventilation, respectively, p=0.05). During the two modes, increasing the back-up rate to Fmax resulted in a greater reduction in PTPdi/min (p=0.001), which was more pronounced during AC/VT ventilation, due to the automatic adjustment of the inspiratory/expiratory time ratio. CONCLUSIONS: Increasing the back-up rate during PS and AC/VT ventilation decreases respiratory effort in young patients with CF, but this effect was more marked with AC/VT ventilation.

Adolescent↗
PubMed2004

Tracheal double-lumen ventilation attenuates hypercapnia and respiratory acidosis in lung injured pigs.

OBJECTIVE: Evaluation of ventilatory and circulatory effects with coaxial double-lumen tube ventilation for dead-space reduction as compared with standard endotracheal tube ventilation. DESIGN: Experimental study in a pig model of lung lavage induced acute lung injury. SETTING: University research laboratory. MEASUREMENTS AND RESULTS: Tidal volumes of 6, 8 and 10 ml/kg body weight with a set respiratory rate of 20 breaths per minute were used in a random order with both double-lumen ventilation and standard endotracheal tube ventilation. Measurements of ventilatory and circulatory parameters were obtained after steady state at each experimental stage. With a tidal volume of 6 ml/kg, PaCO(2) was reduced from 10.9 kPa (95% CI 9.0-12.9) with a standard endotracheal tube to 8.2 kPa (95% CI 7.0-9.4) with double-lumen ventilation. This corresponds to a reduction in carbon dioxide levels by 25%. At 6 ml/kg, pH increased from 7.17 (95% CI 7.09-7.24) with a standard endotracheal tube to 7.27 (95% CI 7.21-7.32) with double-lumen ventilation. Tracheal pressure was monitored continuously and no difference between single- or double-lumen ventilation was noted at corresponding levels of ventilation. There was no formation of auto-PEEP. Partial tube obstruction due to secretions was not observed during the experiments. CONCLUSIONS: Coaxial double-lumen tube ventilation is an effective adjunct to reduce technical dead space. It attenuates hypercapnia and respiratory acidosis in a lung injury pig model.

Acidosis, Respiratory↗
PubMed2004

Prone position improves mechanics and alveolar ventilation in acute respiratory distress syndrome.

OBJECTIVE: We tested the hypothesis that ventilation in the prone position might improve homogenization of tidal ventilation by reducing time-constant inequalities, and thus improving alveolar ventilation. We have recently reported in ARDS patients that these inequalities are responsible for the presence of a "slow compartment," excluded from tidal ventilation at supportive respiratory rate. DESIGN: In 11 ARDS patients treated by ventilation in the prone position because of a major oxygenation impairment (PaO(2)/FIO(2)</=100 mm Hg) we studied mechanical and blood gas changes produced by a low PEEP (6+/-1 cm H(2)O), ventilation in the prone position, and the two combined. RESULTS: Ventilation in the prone position significantly reduced the expiratory time constant from 1.98+/-0.53 s at baseline with ZEEP to 1.53+/-0.34 s, and significantly decreased PaCO(2) from 55+/-11 mm Hg at baseline with ZEEP to 50+/-7 mm Hg. This improvement in alveolar ventilation was accompanied by a significant improvement in respiratory system mechanics, and in arterial oxygenation, the latter being markedly increased by application of a low PEEP (PaO(2)/FIO(2) increasing from 64+/-19 mm Hg in supine position with ZEEP to 137+/-88 mm Hg in prone with a low PEEP). CONCLUSION: In severely hypoxemic patients, prone position was able to improve alveolar ventilation significantly by reducing the expiratory time constant.

Analysis of Variance↗
PubMed2005

Animal model of unilateral ventilator-induced lung injury.

OBJECTIVE: To design, implement, and test a selective lung ventilator for setting a rat model of unilateral ventilator-induced lung injury (VILI). DESIGN AND SETTING: Interventional animal study in a university laboratory for animal research. SUBJECTS: Anesthetized and paralyzed male Wistar rats. INTERVENTIONS: A selective ventilator designed to apply varying tidal volume, PEEP, and breathing gas to each lung of the rat was implemented and evaluated. Five control animals were ventilated at 7 ml/kg (3.5 ml/kg each lung). Unilateral VILI was induced in six animals subjected to selective ventilation (3.5 ml/kg in one lung and 15 ml/kg in the other lung). After 3 h of ventilation the animals were killed and the lungs excised. MEASUREMENTS AND RESULTS: Lung edema was assessed by means of the ratio between wet and dry lung weights. No significant differences were found in lungs of control animals (5.16+/-0.22 and 4.96+/-0.25), but the W/D ratio in the over ventilated lung (8.98+/-3.80) was significantly greater than that in the normally ventilated lung (4.76+/-0.15), indicating selective induction of lung edema by over stretch. CONCLUSIONS: This selective ventilator can be implemented into a rat model of unilateral VILI to gain further insight into the mechanisms of pulmonary injury induced by different ventilatory strategies.

Animals↗
PubMed2006

Adaptive mechanical backup ventilation for preterm infants on respiratory assist modes - a pilot study.

BACKGROUND: Mechanical respiratory-assist modes, such as assist/control, low-rate intermittent mandatory ventilation, continuous positive airway pressure, or proportional assist ventilation (PAV), require a continuous respiratory effort. Because of the frequent occurrence of periodic breathing and/or apnea, mechanical backup ventilation must be initiated during episodes of reduced or absent respiratory drive to maintain gas exchange. The common approach to this problem is a regular conventional mechanical ventilation, which is initiated and withdrawn in an "on/off" function. OBJECTIVE: To develop and evaluate a mechanical backup ventilation mode that is adaptive to the rapidly changing breathing pattern of preterm infants. DESIGN: Prospective randomized clinical crossover trial. SETTING: Neonatal intensive care unit at the University of Munich, Germany. PATIENTS: Preterm infants undergoing PAV. INTERVENTIONS: The infants were ventilated with PAV using a newly developed adaptive backup support, with and without pulse-oximetry-guided operation (SpO(2)-sensitive backup). Each infant was ventilated with both modes of backup support on 2 consecutive days, with the sequence randomized. MEASUREMENTS AND RESULTS: The analysis on 11 preterm infants showed a statistically significant and clinically relevant reduction of the incidence (33%) and duration of oxygen desaturations (52%) when SpO(2)-sensitive adaptive backup support was used. CONCLUSIONS: SpO(2)-sensitive adaptive backup proved safe and effective in reducing the incidence and duration of oxygen desaturation in this short-term trial. This technology is potentially applicable to other assisted modalities of ventilation, such as noninvasive nasal ventilation.

Female↗
PubMed2005

Comparison of mouth-to-mouth resuscitation and Combitube ventilation in a bench model.

CONTEXT: In addition to heart massage, the primary goal of cardiopulmonary resuscitation is efficient oxygenation and ventilation. OBJECTIVE: To compare the ease of learning and handling of standard mouth-to-mouth resuscitation with the Combitube (Tyco Healthcare Nellcor, Pleasanton, CA) ventilation. METHODS: After a 30 minute theoretical introduction and demonstration of mouth-to-mouth resuscitation and use of the Combitube in mannequins, following American Heart Association guidelines, 26 adolescent school children (15 of them 14 years old, 11 of them 10 years old) undertook two ventilation trials, each consisting of five single ventilations, with each technique. Only the second trial with each technique was evaluated. Qualitative implementation (grades: very good, good, failed) was evaluated, several procedure-related time points were recorded, and tidal volumes (ml) were measured. RESULTS: With mouth-to-mouth resuscitation, the time interval until start of first ventilation was 36.5 seconds shorter than with the Combitube (P < 0.001). With the Combitube, the time needed for five single ventilations was 6.4 seconds less than with mouth-to-mouth resuscitation (P < 0.001) and mean tidal volumes were higher (mouth-to-mouth resuscitation, 450 +/- 384 ml, versus Combitube, 735 +/- 358 ml; P < 0.05). CONCLUSION: Most of the school children performed both techniques to a high qualitative level. The study shows that mouth-to-mouth resuscitation and use of the Combitube have equal ease of learning, a precondition for proficient retention of skills. Tidal volumes were significantly higher with the Combitube and, not surprisingly, the time interval until the start of first ventilation was significantly shorter with mouth-to-mouth resuscitation. Regardless of the ventilation technique or device, we believe that subsequent retraining of ventilation skills is very important.

Adolescent↗
PubMed1987

Long-term effects of hydralazine on ventilation and blood gas values in patients with chronic obstructive pulmonary disease and pulmonary hypertension.

Hydralazine has been shown to increase minute ventilation, alveolar ventilation, and arterial partial pressure of oxygen (PaO2) after short-term administration in patients with chronic obstructive pulmonary disease and pulmonary hypertension. The effects of orally administered hydralazine on ventilation and blood gas values were evaluated after six to 18 months of treatment in 10 male patients who had demonstrated an increase in minute ventilation after 24 hours of treatment. Hydralazine was administered at a dose of 200 mg per day during the initial 24 hours and in doses ranging from 40 mg per day to 200 mg per day during long-term therapy. Following 24 hours of treatment, a statistically significant increase in minute ventilation, alveolar ventilation, and PaO2, and reduction in arterial partial pressure of carbon dioxide (PaCO2) were seen both at rest and during exercise. After six to 18 months of hydralazine therapy, the increase in minute ventilation at rest persisted when compared with the pre-hydralazine value (15.3 +/- 1.3 liters/minute versus 13.1 +/- 1.1 liters/minute; p less than 0.05). The improvement in PaO2 at rest continued relative to the pre-hydralazine value (70.9 +/- 3.2 mm Hg versus 65.1 +/- 3.0 mm Hg, p less than 0.05) as did the PaO2 during exercise (60.3 +/- 3.5 mm Hg versus 53.3 +/- 2.0 mm Hg; p less than 0.05). The reduction in PaCO2 at rest persisted compared with the pre-hydralazine value (41.2 +/- 2.4 mm Hg versus 47.0 +/- 3.0 mm Hg; p less than 0.05) as did the PaCO2 during exercise (44.0 +/- 2.8 mm Hg versus 48.0 +/- 2.8 mm Hg; p less than 0.05). No significant changes in minute ventilation, PaO2, or PaCO2 were seen at rest or during exercise, when re-measured after six to 18 months in an age- and sex-matched control group of 10 patients who did not receive hydralazine. These results demonstrate that the short-term effects of hydralazine on ventilation and blood gas values persisted after six to 18 months of treatment in this sample of patients, some of whom received doses less than 200 mg per day.

Blood Gas Analysis↗
PubMed1990

Mechanical ventilation in patients with acute severe asthma.

PURPOSE: Acute respiratory failure necessitating intubation and mechanical ventilation in patients with acute severe asthma is relatively uncommon, and there are few data available regarding positive pressure ventilation in critically ill patients with asthma. We therefore decided to evaluate our experience with the use of mechanical ventilation for acute asthma and to critically review previous reports on this subject. PATIENTS AND METHODS: A retrospective analysis of all medical records of patients who required mechanical ventilation for acute severe asthma was performed for the period of 1980 to 1988. Various clinical parameters were reviewed and examined via Fisher's exact test for association with survival. RESULTS: Twenty-seven patients who underwent ventilation for a total of 32 episodes of mechanical ventilation comprised our study group. The overall mortality was 22%. A total of 76 complications were documented, including six episodes of barotrauma. The mean duration of artificial ventilation was 114 hours for nonsurvivors and 77 hours for survivors (p less than 0.05). CONCLUSION: Although there appears to be a trend toward increased survival after mechanical ventilation for acute asthma, ventilation of critically ill asthmatic patients continues to be a potentially perilous venture associated with significant morbidity and mortality.

Acute Disease↗
PubMed1991

Clothing ventilation - update and applications.

The Environmental Ergonomics Unit at the P.O.W. provided a forum for the discussion and consolidation of ideas regarding the origins, current progress and the future development of the Clothing Ventilation Index. Crockford et al (1972) first developed the concept of clothing ventilation. The basic technique employs a trace gas dilution method for measuring the ventilation of the clothing microclimate. Ventilation is vital to the removal of sensible and insensible heat and, therefore, an important determinant of thermal comfort. Two techniques (Lotens and Havenith, 1986, 1988; Reischl et al, 1987) have subsequently been developed. The former method results in an average ventilation value for the total clothed-body surface area, whereas the latter method also takes into consideration regional changes in garment design as separate entities from the total ventilation, allowing for local modification in garment design. The Clothing Ventilation Index is a quantitative, relatively inexpensive, fast, reliable and repeatable technique. It can be used in context, in the working environment to predict the effectiveness, preference and suitability of garments and clothing assemblies; firstly, to ensure that protective clothing is worn and used correctly, and secondly, to improve performance by minimising heat strain, sweat retention and thermal discomfort. Further work on validating the techniques in terms of human responses to the thermal environment is required. Questions were also raised as to whether human beings or manikins should be used. The use of human beings in dynamic situations is of paramount importance; however, manikins could be used for purely physical measurements to test various assumptions in evaluating clothing ventilation. It is essential that body dimensions and posture are always specified. The seminar enabled researchers to identify with the proposed techniques, outline the advantages and importance of the Clothing Ventilation Index and focus future studies.

Journal Article↗
PubMed1987

Hypoxemic threshold for lung ventilation in the toad.

The relationship between the activity of the buccal force pump, expressed as the time integral of positive buccal pressure, and PaO2 was investigated in conscious toads, Bufo marinus, unidirectionally ventilated at a high flow rate (240-260 ml/min). The high ventilatory flow rate meant that PaO2 was largely independent of the animal's ventilatory activity so that the relationship between pulmonary ventilation and PaO2 was effectively open-loop. The hypoxemic threshold (PaO2) for lung ventilation was 54.2 mm Hg in hypocapnia (PaCO2 = 4.7 +/- 0.3 mm Hg), 82.6 mm Hg in normocapnia (PaCO2 = 11.6 +/- 0.2 mm Hg), and 137.9 mm Hg in hypercapnia (PaCO2 = 20.1 +/- 0.1 mm Hg). Unidirectional ventilation with 20% O2 in N2, a condition in which the toads were normoxic but hypocapnic, stopped pulmonary ventilation cycles. Taken with existing evidence that hyperoxia stops pulmonary ventilation even under conditions in which PaCO2 is elevated this suggests that hypoxic and hypercapnic stimuli summate to drive lung ventilation in the toad. Bilateral denervation of the carotid labyrinths decreased pulmonary ventilation in absolute terms, but did not reduce the proportionate increase in pulmonary ventilation in response to normocapnic hypoxia, suggesting that chemoreceptors within the carotid labyrinth may contribute to, but are not solely responsible for, the hypoxemic ventilatory drive.

Animals↗
PubMed1995

Properties of lavage material from excised lungs ventilated at different temperatures.

We studied the phospholipid (PL) and protein contents, the PL composition, and some of the surface properties of lavage materials obtained from freshly excised rat lungs and excised lungs which had been ventilated at different temperatures (22, 37, and 42 degrees C). Ventilation (60 breaths/min) was carried out at constant tidal volume with periodic sighs for one hour. Although there is slightly more lavageable PL and protein in lungs ventilated at 22 degrees C than in freshly excised lungs, there is no difference in the PL composition or surface properties of lavage materials from these lungs. However, as the temperature at which lungs are ventilated is increased to 37 degrees and 42 degrees C, there is(are): 1) a reduction in lavage fluid PL, 2) a reduction in the relative amounts of total phosphatidylcholines (PC) and disaturated PC (DSPC), the major surface active component of pulmonary surfactant, 3) an increase in unsaturated PC, and 4) increases in total protein and nonsedimentable protein (100,000 g; 2 hr) in the lavage materials. There are also differences in the surface properties of the lavage materials from lungs ventilated at higher temperatures when compared with freshly excised lungs or lungs ventilated at 22 degrees C, probably as a result of the changes in composition. Maximal surface tension is greater for lavage materials from lungs ventilated at 37 degrees C. For lungs ventilated at 42 degrees C, maximal and minimal surface tension values are increased. These results demonstrate that there are differences in the composition and surface properties of alveolar lavage materials from excised lungs ventilated at different temperatures.

Animals↗
PubMed2005

Hyperoxic ventilation exacerbates lung reperfusion injury.

OBJECTIVE: It is well known that hyperoxia can be potentially harmful to the ventilated patient, although little is known about the potential effects in the setting of lung reperfusion. We hypothesized that hyperoxic ventilation at the time of reperfusion could worsen the effects of lung reperfusion injury. METHODS: Using an ex vivo, blood perfused, isolated rabbit lung system, we evaluated the effects of hyperoxic (fraction of inspired oxygen = 100%, n = 10) versus normoxic (room air, n = 10) ventilation after 18 hours of cold ischemia. Lungs were ventilated and perfused for 2 hours. A control group was immediately perfused and ventilated with a fraction of inspired oxygen of 100%. RESULTS: Lung wet/dry ratios demonstrated lower tissue edema in the normoxic group compared with in the hyperoxic group (6.72 +/- 0.89 vs 7.62 +/- 1.14 [mean +/- standard error of the mean], P = .04). Lung ventilation was also significantly better in the normoxic group versus the hyperoxic group (PCO2 = 28.96 +/- 2.01 vs 36.68 +/- 3.20 mm Hg, P = .04). Conversely, lung oxygenation after 2 hours of reperfusion (normoxic group ventilated for the last 15 minutes on 100% fraction of inspired oxygen) was not significantly different between groups (PO2 = 590.2 +/- 50.1 vs 499.6 +/- 67.5 mm Hg, P = .25). CONCLUSIONS: Ventilating lungs with 100% fraction of inspired oxygen at the time of reperfusion could increase the risk of lung reperfusion injury at the time of transplantation. Thus the patient should be ventilated with as low a fraction of inspired oxygen as possible to achieve adequate oxygen saturations during this critical reperfusion period.

Animals↗
PubMed2005

Assessment of respiratory output in mechanically ventilated patients.

Mechanically ventilated patients are subject to few pathophysiologic disturbances that have such intuitive importance as abnormal function of the respiratory output. Abnormal function of the respiratory output plays a fundamental role in all aspects of mechanical ventilation: in determining which patients require mechanical ventilation, in determining the interaction between a patient and the ventilator, and in determining when a patient can tolerate discontinuation of mechanical ventilation. Monitoring indexes such as the rate of rise in electrical activity of the diaphragm, Po.1, (dP/dt)max, and Pmus, has provided insight into the performance of the respiratory centers in critically ill patients, but these methods require considerable refinement. A large body of research on measurements of energy expenditure of the respiratory muscles, such as pressure-time product, and measurements of inspiratory effort, such as the tension-time index, is currently accumulating. Several challenges, however, lay ahead regarding these indices. First, there is the need to identify the correct level of pressure generation and respiratory muscle effort that should be attained in the day-to-day management of mechanically ventilated patients. The correct titration of ventilator setting should not cause iatrogenic muscle damage because the support is excessive or insufficient. One of the challenges in reaching this goal is that for the same patient, different underlying pathologic conditions (eg, sepsis or ventilator-associated muscle injury) may require different levels of support. Second, many of the measurements of pressure generation and effort have been confined to the research laboratory. Modifications of the technology to achieve accurate measurements in the intensive care unit-outside of the research laboratory--are needed. To facilitate individual titration of ventilator settings, the new technologies must provide easier access to quantification of drive, pressure output, and effort. Finally, more research is needed to define the effect of monitoring respiratory output on patient outcome and containment of costs.

Animals↗
PubMed2006

Ventilator management protocols in pediatrics.

Management of mechanical ventilation is a complex process with outcomes affected by multiple patient and caregiver variable. Well-constructed protocols represent the synthesis of best available evidence regarding ventilator management. In adults, protocols improve important outcomes such as duration of mechanical ventilation, length of stay, and complication rates; however, protocols are not uniformly successful. In pediatrics, the available evidence does not suggest that ventilator management protocols should be adopted routinely, which may be due to pediatric-specific attributes such as a generally shorter weaning duration. Evidence suggests support for protocols to carefully titrate sedation. In addition, daily assessment of SBTs improves patient outcomes and should be more uniformly adopted in pediatrics. Ventilator-related outcomes may be affected by other confounding factors such as nutrition and fluid balance. Specific subpopulations, such as children who have congenital heart disease, may present opportunities for focused use of ventilator management protocols. Protocolized ventilation has an important place in trials of new therapeutic strategies such as surfactant or proning. It is hoped that future research will further define the appropriate use of protocols in the general PICU population. Although specific protocols cannot be routinely recommended, a multidisciplinary team approach to synthesizing available literature and determining best practice is a useful model. This approach will foster "team ownership" of ventilator management by all involved, thus engendering the best possible outcomes for critically ill children who require mechanical ventilation.

Child↗
PubMed2006

Comparison of mouth-to-mouth, mouth-to-mask and mouth-to-face-shield ventilation by lay persons.

OBJECTIVE AND METHODS: A prospective randomised study on 70 volunteers without previous first aid education (42 males, 28 females, mean age 17) was performed to compare mouth-to-mouth ventilation (MMV, n = 24) versus mouth-to-pocket-mask ventilation (MPV, n = 25) and mouth-to-face-shield ventilation (MFV, n =21), and to evaluate if an instruction period of 10 min would be sufficient to teach lay persons artificial ventilation. Every volunteer performed three ventilation series using a bench model of an unprotected airway. RESULTS: MMV and MPV show higher mean tidal volume (TV) than MFV (values of series 3: 976 +/- 454 and 868 +/- 459 versus 604 +/- 328 ml, P = 0.002 and P = 0.025, respectively). We found a higher inter-individual variation in TV than in previous studies (P = 0.031). The recommended TV of 700-1000 ml was reached in only 23%, most frequently with MPV (MMV 16.7%, MPV 32%, MFV 19%) but the difference was not significant (P = 0.391). However, we found a significantly higher percentage with a TV below 700 ml with MFV (MMV 33.3%, MPV 36%, MFV 66.7% P = 0.047) and a significantly higher percentage of TV exceeding 1000 ml with MMV (MMV 50%, MPV 32%, MFV 14.3%) (P = 0.039). "Stomach" inflation was highest with MMV (79.2%) followed by MPV (52%) and MFV (42.9%) (P = 0.034). We found further differences between the sexes; males produced a higher TV (P = 0.003) and a higher percentage of stomach inflation (P = 0.029). CONCLUSION: MPV showed the best ventilation quality. It resulted in a more adequate TV than MMV and MFV and lower stomach inflation than MMV. Only a relatively low percentage of ventilations were within the recommended range for TV and this may be related to the short training duration. We found different performances between the sexes, a high inter-individual variation and mainly a low ventilation quality. Therefore, further studies have to focus more on teaching duration, sex differences and ventilation quality.

Adolescent↗