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PubMed2007

Insights in pediatric ventilation: timing of intubation, ventilatory strategies, and weaning.

PURPOSE OF REVIEW: Mechanical ventilation is a common intervention provided by pediatric intensivists. This fact notwithstanding, the management of mechanical ventilation in pediatrics is largely guided by a few pediatric trials along with careful interpretation and application of adult data. RECENT FINDINGS: A low tidal volume, pressure limited approach to mechanical ventilation as established by the Acute Respiratory Distress Syndrome Network investigators, has become the prevailing practice in pediatric intensive care. Studies by these investigators suggest that high positive end expiratory pressure and recruitment maneuvers are not uniformly beneficial. High frequency oscillatory ventilation continues to be evaluated in an attempt to provide 'open lung' ventilation. Airway pressure release ventilation is a newer mode of ventilation that may combine the 'open lung' approach with spontaneous breathing. Prone positioning was demonstrated in a recent pediatric trial to have no effect on outcome, while calfactant was found to potentially improve outcomes in pediatric acute respiratory distress syndrome. Ventilator weaning protocols may not be as useful in pediatrics as in adults. Systemic corticosteroids decrease the incidence of post extubation stridor and may reduce reintubation rates. SUMMARY: Mechanical ventilation with pressure limitation and low tidal volumes has become customary in pediatric intensive care units, and this lung protective approach will continue into the foreseeable future. Further investigation is warranted regarding use of high frequency oscillatory ventilation, airway pressure release ventilation, and surfactant to assist pediatric intensivists in application of these therapies.

Child↗
PubMed2006

Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems.

UNLABELLED: Effective ventilation in general hospital wards is important for controlling the airborne transmission of infectious respiratory diseases. Experiments have been carried out to increase our understanding of the interaction of the breathing flows of two individuals in a full-scale experimental hospital ward with three ventilation systems, i.e. mixing, downward and displacement ventilation. Two life-size breathing thermal manikins were used to simulate a source patient and a receiving patient. The exhalation jet from a bed-lying manikin was visualized using smoke. N2O was used as tracer gas to simulate the droplet nuclei exhaled by patients; and the spatial distribution of its concentrations was measured. Our experimental results show that for both mixing and downward ventilation, the exhaled jet penetrates a short distance and is diluted quickly by ventilation air. The exhaled droplet nuclei are well mixed in the ward. Bed distance does not affect the personal exposure of the receiving patient. For displacement ventilation, the exhaled jet can penetrate a long distance. A high concentration layer of exhaled droplet nuclei because of thermal stratification locking has also been observed with displacement ventilation. This work is useful for identifying an appropriate ventilation method that can remove droplet nuclei more effectively and minimize the risk of cross-infections in a hospital ward environment. PRACTICAL IMPLICATIONS: As one of the major potential sources for infectious droplet nuclei in a hospital environment, exhalation flows of an infected patient can interact with the respiratory activities of other close individuals and with the room ventilation systems. Our latest results provide information on the penetration of exhalation jets into the ambient environment in different ventilation systems. This work is useful in identifying an appropriate and effective ventilation method for removing droplet nuclei more effectively, and thus minimizing the risk of cross-infections in hospital wards with multiple beds.

Air Movements↗
PubMed1992

Domiciliary nocturnal nasal intermittent positive pressure ventilation in hypercapnic respiratory failure due to chronic obstructive lung disease: effects on sleep and quality of life.

BACKGROUND: Domiciliary assisted ventilation, using negative or positive pressure devices, is an effective treatment for respiratory failure due to chest wall deformity and neuromuscular disease. Negative pressure ventilators have been used with some success in patients with chronic obstructive lung disease in hospital, but attempts to continue treatment at home have been disappointing. This study evaluates the practicalities of nasal intermittent positive pressure ventilation at home in patients with chronic obstructive lung disease and the effect on sleep and quality of life. METHODS AND RESULTS: Twelve patients with chronic obstructive lung disease and hypercapnic respiratory failure received nasal intermittent positive pressure ventilation at home during sleep. At six months eight were continuing with the ventilation. One patient had died and three had withdrawn because they were unable to sleep with the equipment. Full polysomnography performed during ventilation in patients continuing treatment at six months showed an increase in mean PaO2 of 11% (+2% to +23%) and lower mean transcutaneous carbon dioxide tensions (by -2.7 (-1.3 to -5.1) kPa) overnight compared with spontaneous breathing before the start of nasal intermittent positive pressure ventilation. Total sleep time and sleep efficiency changed during ventilation by +72.5 (+21 to +204) minutes and +5% (-3% to +30%) respectively; sleep architecture and the number of arousals were unchanged. Quality of life did not change but was no worse during ventilation. At one year seven patients were still using the ventilator and PaCO2 and bicarbonate ion concentration during the day had improved further by comparison with the values at six months (change from baseline -1.7 (-2.1 to -0.6) kPa, p less than 0.05, and -6.3 (-11.9 to -4) mmol/l, p less than 0.05). CONCLUSIONS: Nasal intermittent positive pressure ventilation can be used effectively at home during sleep in selected patients with chronic obstructive lung disease. Its future place in management can be established only by formal comparison with long term oxygen therapy.

Female↗
PubMed2000

Correlation between ventilation and perfusion determines VA/Q heterogeneity in endotoxemia.

Endotoxin increases ventilation-to-perfusion ratio (VA/Q) heterogeneity in the lung, but the precise changes in alveolar ventilation (VA) and perfusion that lead to VA/Q heterogeneity are unknown. The purpose of this study was to determine how endotoxin affects the distributions of ventilation and perfusion and the impact of these changes on VA/Q heterogeneity. Seven anesthetized, mechanically ventilated juvenile pigs were given E. coli endotoxin intravenously, and regional ventilation and perfusion were measured simultaneously by using aerosolized and injected fluorescent microspheres. Endotoxemia significantly decreased the correlation between regional ventilation and perfusion, increased perfusion heterogeneity, and redistributed perfusion between lung regions. In contrast, ventilation heterogeneity did not change, and redistribution of ventilation was modest. The decrease in correlation between regional ventilation and perfusion was responsible for significantly more VA/Q heterogeneity than were changes in ventilation or perfusion heterogeneity. We conclude that VA/Q heterogeneity increases during endotoxemia primarily as a result of the decrease in correlation between regional ventilation and perfusion, which is in turn determined primarily by changes in perfusion.

Animals↗
PubMed1979

Ventilation-perfusion imbalance after head trauma.

To investigate the role of ventilation-perfusion (VA/Q) imbalance in the hypoxemia observed after head injury, 5 male subjects (17 to 26 years of age) with isolated head trauma and subsequent hypoxemia were studied. Disturbances of ventilation and perfusion were assessed using the steady-state elimination of six inert gases of different solubilities. Paired studies were conducted during mechanical ventilation with a volume-cycled ventilator and during spontaneous ventilation. Distributions recovered from studies of spontaneous ventilation show a mode of ventilation and perfusion near a VA/Q of 1.0. In addition, 41% of the cardiac output was distributed to a second population of lung units with low VA/Q (less than 0.1) and shunt. During mechanical ventilation, perfusion to these regions of low VA/Q decreased to 21% of the cardiac output, whereas shunt fraction was unchanged. This was associated with a marked broadening of the VA/Q mode near 1.0, relative to the studies during spontaneous ventilation. Mean functional residual capacity during mechanical ventilation was not different from that during spontaneous ventilation. These results suggest that head injury can lead to hypoxemia through a failure of VA/Q regulatory mechanisms.

Adolescent↗
PubMed1997

Ventilation and gas exchange in lizards during treadmill exercise.

The extent to which lizards ventilate their lungs during locomotion is controversial. Direct measurements of airflow across the nostrils suggest a progressive reduction in tidal volume and minute ventilation with increased running speed, while other studies have demonstrated that arterial PO2 remains constant during exercise. To resolve these conflicting findings, we measured minute ventilation and gas exchange rate in five specimens of Varanus exanthematicus and five specimens of Iguana iguana during treadmill locomotion at speeds between 0.14 and 1.11ms-1 at 35 degrees C. These speeds are much lower than maximal running speeds, but are greater than the maximal aerobic speed. In both species, the ventilatory pattern during locomotion was highly irregular, indicating an interference between locomotion and lung ventilation. In Varanus exanthematicus, treadmill locomotion elicited a six- to eightfold increase in minute ventilation from a pre-exercise level of 102mlkg-1min-1, whereas the rate of oxygen uptake increased approximately threefold (from 3.9 to 12.6mlkg-1min-1). After exercise, both minute ventilation and gas exchange rate decreased immediately. Because minute ventilation increased more than did oxygen consumption, an increase in lung PO2 during exercise is predicted and, thus, Varanus exanthematicus appears effectively to ventilate its lungs to match the increased metabolic rate during locomotion at moderate speed. In Iguana iguana, both minute ventilation and gas exchange rate increased above resting values during locomotion at 0.28ms-1, but both decreased with further increases in locomotor speed. Furthermore, following exercise, both minute ventilation and oxygen uptake rate increased significantly. Iguana iguana, therefore, appears to be unable to match the increased oxygen demand with adequate ventilation at moderate and higher speeds.

Animals↗
PubMed2002

Ventilator-associated pneumonia in pediatric intensive care unit patients: risk factors and outcomes.

OBJECTIVES: To determine the rates, risk factors, and outcomes of ventilator-associated pneumonia in pediatric intensive care unit (PICU) patients. METHODS: A prospective cohort study was conducted at the St Louis Children's Hospital PICU on all patients who were admitted to the PICU from September 1, 1999, to May 31, 2000, except those who died within 24 hours, were > or =18 years of age, or were neonatal intensive care unit patients on extracorporeal membrane oxygenation. The primary outcome measured was the development of ventilator-associated pneumonia. Secondary outcomes were death and hospital and PICU length of stay. Multiple logistic regression analysis was performed to determine independent predictors for ventilator-associated pneumonia. RESULTS: There were 34 episodes of ventilator-associated pneumonia in 30 patients of 911 admissions (3.3%) and 595 (5.1%) mechanically ventilated patients. The mean ventilator-associated pneumonia rate was 11.6/1000 ventilator days. By logistic regression analysis, genetic syndrome (odds ratio [OR]: 2.37; 95% confidence interval [CI]: 1.01-5.46), reintubation (OR: 2.71; 95% CI: 1.18-6.21), and transport out of the PICU (OR: 8.90; 95% CI: 3.82-20.74) independently predicted ventilator-associated pneumonia. CONCLUSIONS: Ventilator-associated pneumonia occurs at significant rates among mechanically ventilated PICU patients and is associated with processes of care. Additional studies are necessary to develop interventions to prevent ventilator-associated pneumonia.

Cross Infection↗
PubMed1990

Complications of mechanical ventilation in a children's hospital multidisciplinary intensive care unit.

UNLABELLED: During a 12-week period, 204 consecutive patients admitted to the multidisciplinary intensive-care unit of a children's hospital were prospectively studied for complications of mechanical ventilation. METHOD: A respiratory therapist completed a standardized data form at the end of each shift for each ventilated patient. Patient age, sex, length of ventilation, diagnosis, and complications were noted. Complications were classified as relating to the endotracheal tube (ETT), the ventilator, or the patient's medical management, and were analyzed according to incidence (number per 100 patients or per 100 ventilator days) and to associated mortality. RESULTS: Patients ranged in age from newborn to 24 years. Sixty-three percent were male. Twenty-one percent of patients were managed by the medical staff, 11% by the general surgical staff, and 68% by the cardiac surgical staff. Average length of ventilation was 5.2 days. Overall survival rate was 91.7%. ETT complications reported as number per 100 patients were: pre-necrosis (13.0 [4/57 orally intubated patients and 23/147 nasally intubated patients]), ETT retaping complications (6.0), ETT plugging (1.0), and self-extubation (3.0). Ventilator complications reported as number per 100 ventilator days were: alarm failures (6.5), ventilator failures (0.7), and circuit problems (7.0). Medical complications reported as number per 100 patients were: massive gastric distension (8.8), right-upper-lobe collapse (4.4), pneumothorax (4.4), subcutaneous air (1.5), and pneumoperitoneum (1.0). ETT and ventilator complications showed no association with mortality. The large number of cardiac infants less than 24 months of age (n = 101) led us to further analyze this group for survival rate. We found that the survival rate was 93% for those requiring less than 7 days mechanical ventilation and 89.3% for those requiring greater than or equal to 7 days. As the study progressed, the respiratory therapists independently noted that their attentiveness to both patient and machine increased as did their awareness of complications. The incidence of alarm failure, circuit problems, and pre-necrosis was higher among the first 103 patients compared to the 101 patients entered into the study subsequently.

Adolescent↗
PubMed2001

Heliox delivery with noninvasive positive pressure ventilation: a laboratory study.

BACKGROUND: There is clinical interest in the use of heliox (helium-oxygen mixture) during noninvasive positive pressure ventilation (NPPV), but delivery of heliox with ventilators designed for NPPV has not been reported. We studied helium concentration ([He]) when an 80%:20% helium:oxygen mixture (heliox) was used with 5 NPPV ventilators (Knightstar, Quantum, BiPAP S/T-D30, Sullivan, and BiPAP Vision). METHODS: A simulated spontaneous breathing lung model was connected to the ventilators with a circuit incorporating a standard leak. Heliox flows of 0, 5, 10, and 18 L/min and oxygen flows of 0 and 10 L/min were titrated into the system at either a proximal position near the lung model or a distal position near the ventilator (titration method). Because the BiPAP Vision has an oxygen delivery module, it was also studied using heliox connected to the air inlet of an oxygen blender, with the blender outlet connected to the oxygen module of the ventilator (blender method). All ventilators were evaluated in spontaneous/timed mode at inspiratory/expiratory pressures of 10/5, 15/5, and 20/5 cm H(2)O. After 5 minutes, [He], oxygen concentration, and pressure in the lung model were recorded. RESULTS: Heliox flow, NPPV settings, site of heliox infusion, and type of ventilator significantly (p < 0.05) affected [He]. [He] was > 60% when heliox flow was 18 L/min in some combinations of settings. The BiPAP S/T-D30 and Quantum occasionally functioned erratically. The BiPAP Vision (blender method) ventilator performed erratically with heliox unless the exhalation port test was bypassed on startup. The addition of heliox flow had no important effect on inspiratory or expiratory positive airway pressure on those breaths during which the ventilators functioned correctly. CONCLUSION: Heliox flow was the most important determinant of [He] when using heliox with NPPV. With heliox there was a potential for ventilator malfunction in some conditions. The clinical implications of these findings remain to be determined.

Helium↗
PubMed2002

Neonatal/pediatric intensive care ventilators.

Neonatal/pediatric intensive care ventilators provide temporary breathing support to preterm and critically ill children who require total or partial assistance to maintain adequate ventilation. Some ventilators are specifically designed for neonatal/pediatric patients, while others--which we call all-patient ventilators--can ventilate the full range of patients from neonates to adults. We evaluated six ventilators from four suppliers: Bird, Dräger, Hamilton, and Siemens. Four of these units are all-patient models, a fifth can ventilate the range from neonatal to pediatric patients, and the sixth is suitable only for neonates. We found that the all-patient units performed at least as well as those designed specifically for neonatal/pediatric patients, and in fact all three of our Preferred units are all-patient ventilators. Unless your clinicians insist on the traditional time-cycled pressure-limited (TCPL) mode, these all-patient units are probably your best choice--and may even save costs, as we discuss in the Money Matters feature. Safe and informed ventilator use is still a vital concern. We continue to stress the importance of thoroughly understanding the characteristics and use of every ventilator model in your facility. This means not only knowing the ventilator's modes, special features, and unique characteristics, but also knowing which alarm settings are appropriate and which are not. This article includes a review of the key points of that topic.

Child↗
PubMed2005

Ventilator graphics and respiratory mechanics in the patient with obstructive lung disease.

Obstruction of the large and small airways occurs in several diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, bronchiectasis, and bronchiolitis. This article discusses the role of ventilator waveforms in the context of factors that contribute to the development of respiratory failure and acute respiratory distress in patients with obstructive lung disease. Displays of pressure, flow, and volume, flow-volume loops, and pressure-volume loops are available on most modern ventilators. In mechanically ventilated patients with airway obstruction, ventilator graphics aid in recognizing abnormalities in function, in optimizing ventilator settings to promote patient-ventilator interaction, and in diagnosing complications before overt clinical signs develop. Ventilator waveforms are employed to detect the presence of dynamic hyperinflation and to measure lung mechanics. Various forms of patient-ventilator asynchrony (eg, auto-triggering and delayed or ineffective triggering) can also be detected by waveform analysis. Presence of flow limitation during expiration and excessive airway secretions can be determined from flow-volume loops. Abnormalities in pressure-volume loops occur when the trigger sensitivity is inadequate, with alterations in respiratory compliance, or during patient-ventilator asynchrony. Thus, ventilator waveforms play an important role in management of mechanically-ventilated patients with obstructive lung disease.

Airway Resistance↗
PubMed2005

Exogenous surfactant administration by asymmetric high-frequency jet ventilation in experimental respiratory distress syndrome.

AIM: To evaluate the efficacy of surfactant administration using the instillation technique by means of asymmetric high-frequency jet ventilation (HFJV). METHODS: Experiments were carried out on tracheotomized, anaesthetized, and paralyzed rabbits. Animals were lung-lavaged with saline and conventionally ventilated with 100% oxygen. After respiratory failure, they were ventilated for additional 2 hours with conventional ventilation (f=30/min) or HFJV (f=300/min). Subgroups were treated with porcine surfactant (Curosurf; 80 mg/mL, dose 200 mg/kg) as a bolus followed by conventional ventilation or instilled into the jet of the ventilator during asymmetric HFJV (inspiration time Ti=30%). In controls, no material was instilled. RESULTS: Bolus administration of Curosurf followed by conventional ventilation in comparison with conventionally ventilated animals without surfactant improved gas exchange (at 60 minutes: PaO(2)/FiO(2), 9.8-/+3.6 vs 22.3-/+8.5 kPa, P=0.020), reduced right-to-left pulmonary shunts (at 60 minutes: 47.8-/+13.8 vs 23.9-/+6.7 %, P<0.006), and reduced inflammatory response in the lungs. Surfactant administration by HFJV in comparison with bolus instillation resulted in even better gas exchange (at 90 minutes: 20.7-/+8.8 vs 39.1-/+10.9 kPa, P=0.005) and reduction of right-to-left pulmonary shunts (at 90 minutes: 29.1-/+7.2 vs 8.0-/+2.2 %, P=0.008). High-frequency jet ventilation with or without surfactant treatment significantly increased pressure-volume recordings and reduced intraalveolar edema in comparison with conventional ventilation-only group. There were no significant differences in inflammatory response between the two tested methods. CONCLUSION: The response to surfactant therapy in experimental lung injury depends on the surfactant delivery method and may be potentiated by high-frequency jet ventilation.

Animals↗
PubMed2005

Improving microbial air quality in air-conditioned mass transport buses by opening the bus exhaust ventilation fans.

The air quality in air-conditioned mass transport buses may affect bus drivers' health. In-bus air quality improvement with the voluntary participation of bus drivers by opening the exhaust ventilation fans in the bus was implemented in the Seventh Bus Zone of Bangkok Mass Transit Authority. Four bus numbers, including bus numbers 16, 63, 67 and 166, were randomly selected to investigate microbial air quality and to observe the effect of opening the exhaust ventilation fans in the bus. With each bus number, 9 to 10 air-conditioned buses (total, 39 air-conditioned buses) were included. In-bus air samples were collected at 5 points in each studied bus using the Millipore Air Tester. A total of 195 air samples were cultured for bacterial and fungal counts. The results reveal that the exhaust ventilation fans of 17 air-conditioned buses (43.6%) were opened to ventilate in-bus air during the cycle of the bus route. The means +/- SD of bacterial counts and fungal counts in the studied buses with opened exhaust ventilation fans (83.8 +/- 70.7 and 38.0 +/- 42.8 cfu/m3) were significantly lower than those in the studied buses without opened exhaust ventilation fans (199.6 +/- 138.8 and 294.1 +/- 178.7 cfu/m3), p < 0.0005. All the air samples collected from the studied buses with opened exhaust ventilation fans were at acceptable levels (< 500 cfu/m3) compared with 4.6% of the air samples collected from the studied buses without opened exhaust ventilation fans, which had high levels (> 500 cfu/m3). Of the studied buses with opened exhaust ventilation fans (17 buses), the bacterial and fungal counts after opening the exhaust ventilation fans (68.3 +/- 33.8 and 28.3 +/- 19.3 cfu/m3) were significantly lower than those before opening the exhaust ventilation fans (158.3 +/- 116.9 and 85.3 +/- 71.2 cfu/m3), p < 0.005.

Air Conditioning↗
PubMed2006

Critical illness and mechanical ventilation: effects on the diaphragm.

Although life-saving, mechanical ventilation is associated with numerous complications. These include pneumonia, cardiovascular compromise, barotrauma, and ventilator-induced lung injury. Recent data from animal studies suggest that controlled mechanical ventilation can cause dysfunction of the diaphragm, decreasing its force-generating capacity--a condition referred to as ventilator-induced diaphragmatic dysfunction (VIDD). The decrease in diaphragmatic contractility is time-dependent and worsens as mechanical ventilation is prolonged. Evidence supporting the occurrence of comparable diaphragmatic dysfunction in critically ill patients is scarce, although most patients receiving mechanical ventilation display profound diaphragmatic weakness. Atrophy, fibers remodeling, oxidative stress, and structural injury have been implicated as potential mechanisms of VIDD. The decrease in diaphragmatic force that occurs during controlled mechanical ventilation is attenuated during assisted modes of ventilation. Whether the decrease in diaphragmatic contractility observed during controlled ventilation contributes to failure to wean from the ventilator is difficult to ascertain. Weaning-failure patients have reasons other than VIDD for respiratory-muscle weakness. Until we have further data, it seems prudent to avoid the use of controlled mechanical ventilation in patients with acute respiratory failure.

Critical Illness↗
PubMed1991

[The "preoxygenation" special function in mechanical ventilators. Medically necessary and an ergonomic plus?].

Hypoxia-related cardiovascular complications and unnecessary monitor and ventilator alarms are well-known problems during tracheobronchial suctioning. Preoxygenation together with temporary muting of acoustic alarms for tracheobronchial suctioning are provided by a single operational control of the ventilator "Evita", software release 9 (Drägerwerk AG). This integrated function was evaluated in medical and ergonomic respects. METHODS. Thirty tracheobronchial suctioning procedures each, with or without preoxygenation, were evaluated. The subjects were patients in our anesthesiological intensive care unit who were under continuous positive-pressure ventilation with FIO2 between 0.25 and 0.6. They ranged in age from 18 months to 72 years. Each patient served as her/his own control after about 1-h delays. Depending on the preference of the nurse, the procedures were either both on-ventilator (via the catheter port) or both off-ventilator suctionings. Arterial samples for blood gas analyses as well as arterial oxygen saturation (SaO2) determinations were taken before preoxygenation, at the moment of disconnection or opening of the catheter port, at reconnection or closure of the port, and 5 min later. Moreover, the number of changes in position of the performing nurse, the number of acoustic ventilator alarms, and the duration of the procedure were recorded. Finally, assessments of the integrated ventilator feature by the 28 participating nurses were collected both as a score from 1 ("most useful and innovative") to 5 ("completely superfluous and distracting") and as detailed statements. RESULTS. Arterial blood gas results and SaO2 courses differentiated as to procedures with or without preoxygenation as well as on-ventilator and off-ventilator suctioning are shown in Table 1 (values are mean +/- standard deviation). Without preoxygenation, most patients did not exhibit threatening drops in SaO2 (values fell from 98.2%) to 97.0% on the average). Nevertheless, preoxygenation provided an additional safety margin (100% saturation throughout the procedure in all patients). Under certain conditions, e.g., low functional residual capacity as in small children or patients with adult respiratory distress syndrome (in 1 of these cases we observed a SaO2 drop to 87%), it is mandatory. Although occurring far less frequently, unnecessary acoustic alarms were not completely excluded by the integrated function because the ventilator would not recognize the insertion of the suction catheter via the catheter port as the expected disconnection. Thus, coughing was able to trigger the "high airway pressure" alarm. As expressed by an average score of 2.8, approval of the integrated ventilator function prevailed among the involved nursing staff.

Adolescent↗
PubMed1996

[Intermittent self-ventilation after respirator weaning].

BACKGROUND: Weaning from the mechanical ventilator often proves to be difficult after prolonged ventilation due to excessive load or decreased capacity of the respiratory muscles. In the present retrospective study we examined the impact of the nocturnal mechanical ventilation during the "post-weaning-period" of long-term ventilated patients. PATIENTS AND METHODS: We studied 43 patients (23 men, 59.1 +/- 14.6 years) with chronic respiratory failure who were transmitted from external ICUs after a mechanical ventilation period of 57.5 +/- 60.3 days. The weaning regime consisted of an individually adapted volume-cycled ventilation. If the patients were hypercapnic (pCO2 > 48 mm Hg) after the first 24-hour-period of spontaneous breathing without supplemental oxygen nocturnal mechanical ventilation was initiated. RESULTS AND CONCLUSIONS: In a retrospective study we could show that the decision to initiate invasive or noninvasive nocturnal mechanical ventilation after successful weaning primarily depends on the question whether a chronic hypercapnic respiratory failure persisted also after weaning from long-term mechanical ventilation. In about 40% of unselected patients nocturnal mechanical ventilation stabilized the weaning success whereas 60% of the patients did not need any further nocturnal mechanical ventilation.

Adult↗
PubMed1996

Aerosol production and aerosol droplet size distribution during mechanical ventilation (IPPV) with a new ultrasonic nebulizer.

Administration of drugs via the airway is increasingly practiced in ICU- and surgical patients. For this purpose, aerosols may be produced by either jet nebulization or ultrasonic droplet generation. In mechanically ventilated patients, aerosol delivery is often insufficient. The influence of the ventilatory pattern on nebulizer efficacy is poorly understood. In the present in vitro study we determined the efficacy of a new ultrasonic nebulizer in delivering aerosolized epoprostenol using defined ventilator settings. We determined aerosol delivery rates, the aerosol droplet size distribution and the impact of the connection tubing on drug delivery, applying adult and infant ventilation patterns. Aerosol production rates ranged from 0.28 to 0.57 ml per minute. Using an adult ventilator setting volume controlled ventilation (CMV) led to a higher aerosol production rate than pressure controlled ventilation (PCV) at identical tidal volumes and mean airway pressures (0.57 ml/min,CMV vs 0.39 ml/min, PCV). With an infant ventilator setting, nebulizer rates were lower than those found for the adult ventilator setting, but did not differ substantially between CMV and PCV mode (0.29 ml/min, CMV vs 0.28 ml/min, PCV). Aerosol delivery rates distal to the endotracheal tube changed according to aerosol production rates (adult mode: 0.18 ml/min, CMV vs 0.10 ml/min, PCV; infant mode: 0.03 ml/min, both CMV and PCV). In the infant ventilation mode, a higher percentage of the aerosol was trapped in the catheter mount as compared to the adult ventilation mode. Mass median droplet diameters for each of the four ventilator settings were almost identical (4.63 to 5.09 micron) and smaller than indicated in the product specifications (8 micron). Delivery rates and sizes of droplets delivered by the new ultrasonic nebulizer SUN 345(R) agree well with previously reported data from comparable settings using diverse nebulizer devices.

Adult↗
PubMed1998

Design, testing, and results of an outcomes-managed approach to patients requiring prolonged mechanical ventilation.

BACKGROUND: Outcomes management that uses critical pathways may decrease costs while improving outcomes for patients who require prolonged mechanical ventilation. OBJECTIVE: To study the efficacy of an outcomes-managed approach to weaning patients from prolonged (more than 3 days) mechanical ventilation. METHODS: A method of multidisciplinary care delivery was designed that included an outcomes manager, a care pathway for patients receiving mechanical ventilation, and weaning protocols. Data collection consisted of three parts: a retrospective review of 124 patients who required prolonged ventilation during a 1-year period before implementation of the care model, a 6-month prospective study in which 91 patients were alternately assigned by month to an outcomes-managed approach or a non-outcomes-managed approach, and a 6-month prospective study of 90 patients in which an outcomes-managed approach without alternate-month assignment was used. RESULTS: Outcomes management had no significant effect on total duration of mechanical ventilation or length of stay in the hospital, days of mechanical ventilation without tracheostomy, days of mechanical ventilation with tracheostomy, or outcome (weaned, withdrawal from mechanical ventilation, death, or transfer without weaning). However, duration of mechanical ventilation was 1.3 days shorter, length of stay in the hospital was 2.1 days shorter, and the cost per case was $ 3341 less for patients in the outcomes-managed group than for patients in the non-outcomes-managed group. CONCLUSION: Outcomes-managed care did not have a significant effect on duration of ventilation, length of stay in the hospital, or outcome in patients receiving long-term mechanical ventilation.

Adult↗