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At least 163 records · Page 9Linked to original sources
PubMed2000

Heliox improves ventilation during high-frequency oscillatory ventilation in pediatric patients.

OBJECTIVE: To describe improved ventilation during high-frequency oscillatory ventilation when a nitrogen-oxygen gas mixture is replaced by a helium-oxygen gas mixture. DESIGN: Case series. SETTING: A tertiary pediatric intensive care unit. PATIENTS: Five patients with hypoxemic respiratory failure who developed persistent respiratory acidosis during treatment with high-frequency oscillatory ventilation. INTERVENTIONS: Introduction of helium-oxygen into a conventional high-frequency oscillatory ventilation circuit. MEASUREMENTS AND MAIN RESULTS: Blood gas values (pH, Pco2, and Po2) were compared in these patients during treatment with high-frequency oscillatory ventilation with nitrogen-oxygen gas flow and then for several hours after a change in treatment to helium-oxygen gas flow. An initial 24% decrease in Pco2 was documented, and an ultimate 43% decrease in Pco2 was observed. The mechanism for this improved ventilation may be related to improved gas flow properties as well as increased CO2 diffusion resulting from helium's low-mass density. Oxygenation was not adversely affected in any way. CONCLUSION: In patients with hypoxemic respiratory failure and in whom respiratory acidosis develops during high-frequency oscillatory ventilation, the use of helium-oxygen rather than nitrogen-oxygen may improve ventilation and decrease ventilator-related trauma. Further investigation is needed to validate these findings and to elucidate the mechanisms of improved ventilation.

Journal Article↗
PubMed2001

The use of intratracheal pulmonary ventilation and partial liquid ventilation in newborn piglets with meconium aspiration syndrome.

OBJECTIVE: To determine whether intratracheal pulmonary ventilation (ITPV) combined with partial liquid ventilation (PLV) improves oxygenation and ventilation at lower mean airway and peak inspiratory pressures when compared with conventional mechanical ventilation in a piglet model of meconium aspiration syndrome. DESIGN: Prospective, randomized, interventional study. SETTING: Animal Research Laboratory at the Children's National Medical Center, Washington, DC. SUBJECTS: Twenty newborn piglets, 1 to 2 wks of age, 1.8-2.8 kg in weight. INTERVENTION: The animals were anesthetized, paralyzed, and intubated with a 4.0 mm (internal diameter) endotracheal tube via a tracheostomy and were ventilated. Catheters were placed in the femoral artery and vein. Seven milliliters per kilogram of 20% human meconium was insufflated into the lungs over 30 mins. Dynamic pulmonary compliance was measured before and after instillation of meconium. Animals were ventilated to maintain arterial blood gases in a normal range, that is, pH = 7.35-7.45, Paco(2) = 40-45 torr (5.3-6.0 kPa), and Pao(2) = 70-90 torr (9.3-12.0 kPa). Ventilator settings were increased as needed to a maximum setting of Fio(2) = 1.0, peak inspiratory pressure (PIP) = 40 cm H(2)O, positive end-expiratory pressure = 5 cm H(2)O, and intermittent mandatory ventilation = 60 bpm. After a period of stabilization, 30 mL/kg of perflubron (Liquivent; Alliance Pharmaceutical Corp., San Diego, CA) was given intratracheally over 30 mins and the animals were randomized to either ITPV or control group. Measurements and RESULTS: Arterial blood gases were taken every 30 mins, and ventilatory settings were adjusted to achieve the targeted blood gas parameters. The animals' temperature, arterial blood pressure, heart rate, and oxygen saturation were monitored continuously. There was a significant decrease in the dynamic pulmonary compliance measurements in both groups immediately after meconium instillation. Compliance measurements after meconium instillation were similar in both groups (0.67 +/- 0.23 mL/cm H(2)O/kg ITPV; 0.88 +/- 0.46 mL/cm H(2)O/kg conventional, p =.17), indicating a similar degree of injury before the administration of perflubron. PIP and mean airway pressures were not significantly different at baseline; however, there was significant difference in PIP at 0, 2, and 4 hrs after administration of perflubron (p <.05). The maximum PIP and mean airway pressure were seen in both groups after meconium instillation before perflubron administration, with a mean PIP of 29.0 +/- 4.6 cm H(2)O in ITPV and 28.8 +/- 2.1 cm H(2)O in control. Mean airway pressure was significantly different between the two groups at 0, 1, 2, 3, and 4 hrs after perflubron administration. Lung pathology showed a uniform distribution of meconium in animals of both groups. The alveolar spaces were relatively clear of meconium and appeared to be well preserved. CONCLUSION: The results of this study indicate that ITPV combined with PLV allows for effective ventilation and oxygenation in piglets with meconium aspiration syndrome at lower mean airway pressure and PIP compared with conventional ventilation combined with PLV.

Journal Article↗
PubMed2004

Ventilator-associated lung injury in patients without acute lung injury at the onset of mechanical ventilation.

OBJECTIVE: Although ventilation with small tidal volumes is recommended in patients with established acute lung injury, most others receive highly variable tidal volume aimed in part at normalizing arterial blood gas values. We tested the hypothesis that acute lung injury, which develops after the initiation of mechanical ventilation, is associated with known risk factors for ventilator-induced lung injury such as ventilation with large tidal volume. DESIGN: Retrospective cohort study. SETTING: Four intensive care units in a tertiary referral center. PATIENTS: Patients who received invasive mechanical ventilation for > or = 48 hrs between January and December 2001. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The main outcome of interest, acute lung injury, was assessed by independent review of daily digital chest radiographs and arterial blood gases. Ventilator settings, hemodynamics, and acute lung injury risk factors were extracted from the Acute Physiology and Chronic Health Evaluation III database and the patients' medical records. Of 332 patients who did not have acute lung injury from the outset, 80 patients (24%) developed acute lung injury within the first 5 days of mechanical ventilation. When expressed per predicted body weight, women were ventilated with larger tidal volume than men (mean 11.4 vs. 10.4 mL/kg predicted body weight, p <.001) and tended to develop acute lung injury more often (29% vs. 20%, p =.068). In a multivariate analysis, the main risk factors associated with the development of acute lung injury were the use of large tidal volume (odds ratio 1.3 for each mL above 6 mL/kg predicted body weight, p <.001), transfusion of blood products (odds ratio, 3.0; p < 0.001), acidemia (pH < 7.35; odds ratio, 2.0; p =.032) and a history of restrictive lung disease (odds ratio, 3.6; p =.044). CONCLUSIONS: The association between the initial tidal volume and the development of acute lung injury suggests that ventilator-associated lung injury may be an important cause of this syndrome. Height and gender should be considered when setting up the ventilator. Strong consideration should be given to limiting large tidal volume, not only in patients with established acute lung injury but also in patients at risk for acute lung injury.

Aged↗
PubMed2006

A novel model of selective lung ventilation to investigate the long-term effects of ventilation-induced lung injury.

Mechanical ventilation (MV) with large tidal volumes (V(T)) causes ventilator induced lung injury. Whereas immediate effects of short-term injurious ventilation are well studied, little is known about its long-term effects. We aimed to establish an animal model of selective injurious MV, permitting assessment of the long-term course of ventilation-induced lung injury. In anesthetized and instrumented rats (n = 26), laryngoscopy was performed, and one cannula for MV was placed in the left main bronchus and a second one in the trachea. Two ventilators were used to ventilate the left lung with high (20 mL/kg) and the right lung with low (4 mL/kg) V(T). In control animals, both lungs received low V(T). After 2 h of MV, animals were extubated and observed for 24 h and then killed. Left and right lungs were excised and sampled for further investigations. Survival in animals ventilated with the high V(T) was 90%. Twenty-four hours after MV, alveolar levels of humoral (tumor necrosis factor alpha, interleukin 6) and cellular (polymorphonuclear leukocytes) inflammatory markers were increased, and histological alterations were present in lungs ventilated with high V(T). A delayed decrease in PaO2 was noted 24 h after MV, with high V(T) delivered to one lung as compared with low V(T) delivered to both lungs. This animal model permits assessment of the long-term course of ventilation-induced lung injury and shows that pulmonary inflammation and histological alterations are present 24 h after unilateral injurious ventilation.

Animals↗
PubMed1977

Weaning from mechanical ventilation by means of intermittent assisted ventilation I.A.V. Case reports.

A new ventilator is described which is capable of interposing controlled breaths synchronized with the patient's own breathing rhythm. This ventilation pattern is called "intermittent assisted ventilation" (IAV). It differs from intermittent mandatory ventilation (IMV) in that each ventilator cycle is triggered by the patient. IAV constitutes a new approach to the problems during the critical period of weaning from mechanical ventilation. Further, this new ventilator provides means for continuous display and recording of airway gas flow and pressures and expired minute volume (EMV) during different types of ventilation, e.g. controlled ventilation, intermittent assisted, and spontaneous ventilation.

Clinical Trials as Topic↗
PubMed1996

Improvement of arterial oxygenation by selective infusion of prostaglandin E1 to ventilated lung during one-lung ventilation.

BACKGROUND: One-lung anesthesia provides a better surgical field for thoracic procedures but also impairs the arterial oxygenation and venous admixture. During one-lung ventilation, pulmonary vasoconstriction is assumed to be present within both ventilated and collapsed lungs. We propose that arterial oxygenation could be optimized by offsetting the vasoconstriction within the microcirculation of ventilated lung. METHOD: In an anesthetized dog model, incremental doses of prostaglandin E1 (PGE1) were selectively infused into the main trunk of the pulmonary artery of the ventilated lung after one-lung ventilation for 60 min (PGE1 group, n = 9). Arterial oxygenation and calculated venous admixture (Qs/Qt) was also assessed in a time-course control group (Control group, n = 5). During two-lung ventilation (FIO2: 0.66), arterial PO2 and venous admixture was 44.2 +/- 3.5 kPa and 10.7 +/- 2.3%, respectively. One-lung ventilation (FIO2: 0.66) with left lung collapsed reduced arterial PO2 to 11.6 +/- 1.7 kPa and increased venous admixture to 40.7 +/- 5.8% (P<0.001). Venous O2 tension also decreased from 6.3 +/- 0.7 kPa to 5.0 +/- 0.6 kPa with a slight increase in mean pulmonary artery pressure and pulmonary vascular resistance (P<0.05). RESULTS: During selective infusion of PGE1 at a dose of 0.04 to 0.2 mu g kg-1 min-1, there was a dose-dependent improvement in arterial PO2 with a parallel reduction of venous admixture during one-lung ventilation. Arterial PO2 increased to a maximum of 23.0 +/- 4.3 kPa, and the venous admixture decreased significantly to a minimum of 27.4 +/- 4.2% by PGE1 at a dose of 0.04-0.4 mu g kg-1 min-1 (P<0.01). PGE1 resulted in a small increase in cardiac output and decreases of pulmonary pressure and pulmonary vascular resistance at a relatively high dose of 0.4 mu g kg-1 min-1 during selective infusion (P<0.05). CONCLUSIONS: These results suggest that a selective pulmonary artery infusion of PGE1 to the ventilated lung within the dose range of 0.04-0.4 mu g kg-1 min-1 is practical and effective to improve arterial oxygenation and reduce venous admixture during one-lung ventilation.

Alprostadil↗
PubMed2006

Bi-level positive airway pressure ventilation maintains adequate ventilation in post-polio patients with respiratory failure.

BACKGROUND: Patients suffering from post-polio syndrome still contribute significantly to the number of patients with chronic respiratory failure requiring home mechanical ventilation (HMV). Many of these patients are treated either with invasive (tracheostomy) or non-invasive (nasal mask) controlled mechanical ventilation i.e. volume-controlled ventilation (VCV). In this group of patients, we have previously shown that bi-level pressure support ventilation (bi-level PSV) decreases the oxygen cost of breathing. The aim of this study was to compare the effect of bi-level PSV, with special regard to the adequacy of ventilation and the oxygen cost of breathing, during the patients' ordinary VCV and spontaneous breathing. METHODS: Eight post-polio patients on nocturnal VCV were investigated. Five of them were tracheostomized and three of them used a nasal mask. Work of breathing was analysed by assessing differences in oxygen consumption (VO2) using indirect calorimetry. Blood gases were obtained regularly to assess adequacy of ventilation. RESULTS: Bi-level PSV decreases the oxygen cost of breathing in post-polio patients with respiratory failure without decreasing ventilation efficiency. Furthermore, PaCO2 decreased significantly using this mode of ventilation (P < 0.05). CONCLUSION: In this study, it was shown that bi-level PSV reduces the oxygen cost of breathing and gave a significant decrease in PaCO2 in PPS patients. These data suggest that bi-level PSV ventilation maintains adequate ventilation in patients who suffer from post-polio syndrome with respiratory failure.

Aged↗
PubMed2005

Closed-loop control of respiratory drive using pressure-support ventilation: target drive ventilation.

By using diaphragm electrical activity (multiple-array esophageal electrode) as an index of respiratory drive, and allowing such activity above or below a preset target range to indicate an increased or reduced demand for ventilatory assistance (target drive ventilation), we evaluated whether the level of pressure-support ventilation can be automatically adjusted in response to exercise-induced changes in ventilatory demand. Eleven healthy individuals breathed through a circuit (18 cm H2O/L/second inspiratory resistance at 1 L/second flow; 0.5-1.0 L/second expiratory flow limitation) connected to a modified ventilator. Subjects breathed for 6-minute periods at rest and during 20 and 40 W of bicycle exercise, with and without target drive ventilation (the target was set to 60% of the increase in diaphragm electrical activity observed between rest and 20 W of unassisted exercise). With target drive ventilation during exercise, the level of pressure-support ventilation was automatically increased, reaching 13.3 +/- 4.0 and 20.3 +/- 2.8 cm H2O during 20- and 40-W exercise, respectively, whereas diaphragm electrical activity was reduced to a level within the target range. Both diaphragmatic pressure-time product and end-tidal CO2 were significantly reduced with target drive ventilation at the end of the 20- (p < 0.01) and 40-W (p < 0.001) exercise periods. Minute ventilation was not altered. These results demonstrate that target drive ventilation can automatically adjust pressure-support ventilation, maintaining a constant neural drive and compensating for changes in respiratory demand.

Adult↗
PubMed1997

Comparison of pressure support ventilation and assist-control ventilation in the treatment of respiratory failure.

STUDY OBJECTIVE: To assess whether pressure support ventilation (PSV) could be used as an alternative ventilatory mode to assist-control (A/C) ventilation in the treatment of respiratory failure. DESIGN: A short-term (4-h) prospective study in which the beneficial effect of PSV on respiratory mechanics, gas exchange, arterial oxygenation, cardiovascular hemodynamics, and oxygen consumption was compared with A/C ventilation. SETTING: ICU of a community hospital. PATIENTS: Forty-five patients (mean age, 62.8 [11.8] years) with respiratory failure secondary to COPD, restrictive disorders, or neuromuscular disease requiring mechanical ventilatory support in the ICU were selected for study. INTERVENTIONS: The mean duration of mechanical ventilation before the study was 7.16 (8.64) days. Patients were switched to the PSV mode of the mechanical ventilator for a period of 4 h after which conventional A/C ventilation was resumed. RESULTS: Patients supported with PSV compared with A/C ventilation showed significantly higher tidal volume, minute ventilation, and inspiratory time in association with significantly lower pressure in the airway and I:E ratio. With regard to gas exchange data, an increase in dead space/tidal volume ratio (VD/VT), decrease in PaO2, and statistically but not clinically significant alteration of arterial oxygenation indexes were noted. However, when patients with COPD, restrictive disorders, and neuromuscular disease were compared, significant changes in arterial oxygenation parameters were found only in patients with restrictive disorders. There were significant decreases in heart rate, systolic pulmonary artery pressure, and pulmonary capillary wedge pressure when PSV was applied. Oxygen transport and oxygen consumption were unchanged. CONCLUSIONS: PSV could be a possible alternative to A/C ventilation in patients with respiratory failure. PSV caused an increase in VD/VT in association with a significantly lower pressure in the airway and I:E ratio. Randomized studies are needed to define the long-term benefits of both respiratory modes and the conditions in which PSV may be a valuable alternative to A/C ventilation.

Adult↗
PubMed2000

Nasal intermittent positive pressure ventilation (NIPPV) versus nasal continuous positive airway pressure (NCPAP) for apnea of prematurity.

BACKGROUND: Apnea of prematurity is almost universal in infants who are born before 34 weeks gestation. Previous randomised trials and systematic reviews have found methylxanthines to be effective in preventing apnea of prematurity. However, recent concerns about potential long term side effects of methylxanthines on the neurodevelopment of low birth weight infants have led to an increased interest in alternate methods of treating apnea of prematurity. Nasal continuous positive airway pressure (NCPAP) is a useful method of respiratory support which reduces the incidence of obstructive or mixed apnea. However, apneic infants managed with NCPAP, with or without methylxanthines, sometimes require endotracheal intubation with its attendant morbidity and cost. Nasal intermittent positive pressure ventilation (NIPPV) is a simple, effective mode of respiratory support for older children and adults. It has been used to treat apnea in preterm infants but case reports of gastrointestinal perforations have limited its widespread use. OBJECTIVES: In preterm infants with recurrent apnea, does treatment with NIPPV lead to a greater reduction in apnea and need for intubation and mechanical ventilation, as compared with treatment with NCPAP? Does NIPPV increase the incidence of gastrointestinal complications, i.e. gastric distension leading to cessation of feeds, or perforation? SEARCH STRATEGY: Medline was searched (1966-2000) using the MeSH terms: infant, newborn (exp) and positive-pressure respiration (exp). Other sources included the Cochrane Controlled Trials Register and CINAHL (search terms: infant, newborn and intermittent positive pressure ventilation); also used were expert informants, previous reviews including cross-references, and conference and symposia proceedings. SELECTION CRITERIA: All randomised and quasi-randomised trials were included. Participants included unventilated preterm infants experiencing apnea of prematurity. Interventions compared were intermittent positive pressure ventilation administered via the nasal route, either by short nasal prongs or nasopharyngeal tube, and nasal CPAP delivered by the same methods. Types of outcome measures: - failure of therapy as defined by apnea that is frequent or severe requiring additional ventilatory support - rates of endotracheal intubation - rates of apnea and bradycardia expressed as events per hour - gastrointestinal complications i.e. abdominal distension requiring cessation of feeds, or GI perforation DATA COLLECTION AND ANALYSIS: Data were extracted independently by the three reviewers. The trials were analysed using relative risk (RR), risk difference (RD) and number needed to treat (NNT) for dichotomous data; means and weighted mean difference (WMD) were used for continuous data. MAIN RESULTS: Two trials, enrolling 54 infants in total, fulfilled the inclusion criteria. Both reported only the short term results (4 to 6 hours) of the interventions. Only one infant (randomised to NCPAP) required intubation during this period. Ryan (1989), in a cross over study of 20 infants, showed no significant difference in rates of apnea (events/hr) between the 2 interventions (WMD -0.10 (-0.53,0. 33)). Lin (1998) randomised 34 infants and demonstrated a greater reduction in frequency of apneas (events/hr) with NIPPV compared to NCPAP (WMD -1.19 (-2.31,-0.07)). Meta-analysis of both trials showed no difference in pCO2 (mmHg) at the end of the 4-6 hour study period (WMD 0.95 (-3.05,4.94)). No data were reported on gastrointestinal complications. REVIEWER'S CONCLUSIONS IMPLICATIONS FOR PRACTICE: NIPPV may be a useful method of augmenting the beneficial effects of NCPAP in preterm infants with apnea that is frequent or severe. Its use appears to reduce the frequency of apneas more effectively than NCPAP. Additional safety and efficacy data are required before recommending NIPPV as standard therapy for apnea. IMPLICATIONS FOR RESEARCH: Future trials with sufficient power should assess the efficacy (reduction in failure of therapy) and safety (GI complications) of NIPPV. Outcomes should be assessed throughout the entire period during which the infant requires assisted ventilation. The recent ability to synchronise NIPPV with an infant's spontaneous respirations is a promising development requiring further assessment.

Apnea↗
PubMed2001

[Unilateral high-frequency jet ventilation supporting one-lung ventilation during thoracic surgical procedures].

We report two cases where surgery on the right lung had to be performed for resection of a malignoma. In both cases, function of the left lung was severely restricted. In the first patient, the volume on this side was reduced by around 50% as the result of a recently performed upper lobe resection. In the second patient, perfusion of the left lung accounted for only 18% of the total lung perfusion. On the basis of these changes we considered conventional one-lung ventilation impracticable and performed surgery using differential lung ventilation. The dependent (left) lung was ventilated by intermittent positive pressure ventilation (IPPV), where the tidal volume in the first patient had to be reduced to 200 ml because of high airway pressures. Ventilation of the non-dependent (right) side was performed simultaneously in both patients by means of high frequency jet ventilation (HFJV). Under this procedure arterial O2 saturation ranged from 96 to 100%, and arterial CO2 partial pressure was 45 mmHg. Surgery was not hindered by ventilation, the postoperative progress was also without complications. The case reports show that with the help of the ventilation regime described (operated side: HFJV, non-operated side: IPPV) lung surgery can be successfully performed on patients who are unsuitable for conventional one-lung ventilation for functional reasons.

Aged↗
PubMed1987

One lung anaesthesia. Cardiovascular and respiratory function compared during conventional ventilation and high frequency jet ventilation.

Ten patients about to undergo left-sided thoracotomy for carcinoma of the lung were entered into a crossover trial to compare cardiovascular and respiratory function during high frequency jet ventilation and conventional mechanical ventilation for one lung anaesthesia. All patients were anaesthetised with a standard technique using double lumen tubes and placed in the lateral position with the left chest open. The results showed no significant differences with regard to ventilation sequence but one lung high frequency jet ventilation gave higher values than one lung conventional ventilation for shunt (p less than 0.01) and positive end expiratory pressure (p less than 0.05) and lower peak inflation pressure values (p less than 0.01). There were no significant differences in cardiac output, pulmonary capillary wedge pressure, arterial carbon dioxide or available oxygen. Surgical conditions were satisfactory during both methods of ventilation and satisfactory gas exchange occurred. It was, however, more difficult to assess adequacy of ventilation during high frequency jet ventilation and the routine use of this method of ventilation is not recommended during one lung anaesthesia.

Anesthesia, Inhalation↗
PubMed2003

Positive pressure ventilation with the open lung concept optimizes gas exchange and reduces ventilator-induced lung injury in newborn piglets.

Previous studies demonstrated that high-frequency oscillatory ventilation using the open lung concept (OLC) resulted in superior gas exchange and a reduction in ventilator-induced lung injury (VILI). We hypothesized that these beneficial effects could also be achieved by applying the OLC during positive pressure ventilation. After repeated whole-lung-lavage, newborn piglets were assigned to either OLC positive pressure ventilation (PPV(OLC)), OLC high-frequency oscillatory ventilation (HFOV(OLC)), or conventional positive pressure ventilation (PPV(CON)) and ventilated for 5 h. In both OLC groups, collapsed alveoli were actively recruited and thereafter stabilized using the lowest possible airway pressures. In the PPV(CON) group, ventilator settings were adjusted to prevent critical hypoxia. Airway pressure, blood gas analysis, pressure-volume curve, and alveolar protein infiltration was recorded. A lung injury score was used for histologic comparison. Mean airway pressures were comparable in the three ventilation groups over time (1.2-1.5 kPa). Arterial oxygenation increased to mean values above 60 kPa in both OLC groups compared with 10 kPa in the PPV(CON) group (p < 0.001). Maximal lung compliance was superior in both OLC groups (PPV(OLC): 91 +/- 23; HFOV(OLC): 90 +/- 31 mL/kPa/kg, p < 0.01) compared with the PPV(CON) group (39 +/- 14 mL/kPa/kg). Alveolar protein infiltration was significantly reduced in the PPV(OLC) group (0.33 +/- 0.10 mg/mL, p < 0.01) and the HFOV(OLC) group (0.40 +/- 0.13 mg/mL, p < 0.01) compared with the PPV(CON) group (0.70 +/- 0.15 mg/mL). Lung injury scores were significantly higher in the PPV(CON) group (33.5 +/- 9.5, p < 0.01) compared with both OLC groups (PPV(OLC): 10.5 +/- 2.6; HFOV(OLC): 11 +/- 2.2). There were no differences between the two OLC groups. We conclude that, in surfactant-depleted newborn piglets, application of the OLC during PPV is feasible and results in superior gas exchange and a reduction in VILI compared with conventional PPV. These beneficial effects are comparable to HFOV.

Animals↗
PubMed2005

Pressure-regulated volume control ventilation vs synchronized intermittent mandatory ventilation for very low-birth-weight infants: a randomized controlled trial.

OBJECTIVE: To test the hypothesis that pressure-regulated volume control (PRVC), an assist/control mode of ventilation, would increase the proportion of very low-birth-weight infants who were alive and extubated at 14 days of age as compared with synchronized intermittent mandatory ventilation (SIMV). STUDY DESIGN: Ventilated infants with birth weight of 500 to 1249 g were randomized at less than 6 hours of age either to pressure-limited SIMV or to PRVC on the Servo 300 ventilator (Siemens Electromedical Group, Danvers, Mass). Infants received their assigned mode of ventilation until extubation, death, or meeting predetermined failure criteria. RESULTS: Mean +/- SD birth weights were similar in the SIMV (888 +/- 199 g, n = 108) and PRVC (884 +/- 203 g, n = 104) groups. No differences were detected between SIMV and PRVC groups in the proportion of infants alive and extubated at 14 days (41% vs 37%, respectively), length of mechanical ventilation in survivors (median, 24 days vs 33 days, respectively), or the proportion of infants alive without a supplemental oxygen requirement at 36 weeks' postmenstrual age (57% vs 63%, respectively). More infants receiving SIMV (33%) failed their assigned ventilator mode than did infants receiving PRVC (20%). Including failure as an adverse outcome did not alter the overall outcome (39% of infants in the SIMV group vs 35% of infants in the PRVC group were alive, extubated, and had not failed at 14 days). CONCLUSION: In mechanically ventilated infants with birth weights of 500 to 1249 g, using PRVC ventilation from birth did not alter time to extubation.

Apgar Score↗
PubMed2006

Rescue high frequency jet ventilation versus conventional ventilation for severe pulmonary dysfunction in preterm infants.

BACKGROUND: Chronic pulmonary disease is a major cause of mortality and morbidity in very low birth weight infants despite increased use of antenatal steroids and surfactant therapy. Ventilator injury and oxygen toxicity are thought to be important factors in the pathogenesis of chronic pulmonary disease. There is evidence in animal studies and adult human studies that high frequency jet ventilation may reduce the severity of lung injury associated with mechanical ventilation. OBJECTIVES: In preterm infants with severe pulmonary dysfunction, does the use of high frequency jet ventilation (HFJV) compared to conventional ventilation (CV) reduce mortality and morbidity without an increase in adverse effects? SEARCH STRATEGY: We searched MEDLINE (1966 - August 2005), Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2005), and EMBASE (1988 - August 2005). Information was also obtained from experts in the field and cross references were checked. SELECTION CRITERIA: Randomized and quasi-randomized controlled trials of rescue high frequency jet ventilation versus conventional ventilation in preterm infants born at less than 35 weeks of gestation or with a birth weight less than 2000 grams with respiratory distress were included in the systematic review. DATA COLLECTION AND ANALYSIS: The standard methods of the Cochrane Neonatal Review Group were used, including independent trial assessment and data extraction. Data were analysed using relative risk (RR) and risk difference (RD). MAIN RESULTS: Two randomized trials were identified. One trial (Engle 1997) was excluded as the study was restricted to term and near-term infants. The included trial (Keszler 1991) randomized 166 preterm infants and reported data on 144 infants. Cross-over to the alternate treatment was permitted if the initial treatment failed. There was no statistically significant difference in the overall mortality (including survival after cross-over) between the two groups [RR 1.07, (95% CI 0.67, 1.72)]. The survival by original assignment was identical. In a secondary analysis, the study demonstrated rescue treatment with HFJV, up until the time of cross-over, was associated with lower mortality, [RR 0.66 (95% CI 0.45,0.97)]. No significant differences were found in the incidence of CLD in survivors at 28 days of age, IVH, new air leaks, airway obstruction and necrotizing tracheobronchitis. AUTHORS' CONCLUSIONS: There was no significant difference in the overall mortality between rescue high frequency jet ventilation and conventional groups. In a secondary analysis, rescue treatment with HFJV, up until the time of cross-over, was associated with lower mortality. There was no significant increase in adverse effects like intraventricular hemorrhage, new air leaks, airway obstruction and necrotizing tracheobronchitis with rescue high frequency jet ventilation. The included study was done before the introduction of surfactant and widespread use of antenatal steroids. The number of infants included was small and there were high numbers of post randomization exclusions. Due to the crossover design and small numbers of infants in the included study, there is insufficient information to assess the effectiveness of rescue HFJV in preterm infants. Studies that target the most at-risk population and have appropriate power to assess some of the important outcomes are needed. These trials would also need to incorporate long term pulmonary and neurodevelopmental outcomes.

High-Frequency Jet Ventilation↗
PubMed2004

High-frequency ventilation versus conventional ventilation for treatment of acute lung injury and acute respiratory distress syndrome.

BACKGROUND: High-frequency ventilation is often used to treat patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) but the effect of this treatment on clinical outcomes has not been well established. OBJECTIVES: The objective of this review is to examine the effect of high-frequency ventilation compared with conventional ventilation as a therapy for ALI or ARDS in children (1 to 17 years old) and adults in order to quantify its effect on patient outcome (mortality, morbidity and other relevant outcomes). SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, issue 4, 2002), MEDLINE (1966 to October Week 5, 2002), EMBASE (1980 to Week 51, 2002), World Wide Web (www.controlled-trials.com, ARDS clinical network), and used Cited Reference Search (Web of Science 1988 to 2002, for specific reference lists of articles). We also contacted authors from each included trial, as well as manufacturers of high-frequency ventilators and other researchers in the field. SELECTION CRITERIA: Randomized controlled clinical trials of children and adults comparing treatment using high-frequency ventilation with conventional ventilation for patients diagnosed with ALI or ARDS. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. MAIN RESULTS: Two trials met the inclusion criteria for this review. One trial recruited children (including some children less than one year old) (n = 58) and the other recruited adults (n = 148). Both trials used a high-frequency oscillatory ventilator as the intervention and included variable use of lung-volume recruitment strategies. The intervention groups showed a trend towards lower 30 day mortality (children relative risk (RR) 0.83, 95% confidence interval (CI) 0.43 to 1.62; adults RR 0.72, 95% CI 0.50 to 1.03), although neither study showed a statistically significant difference. Similarly, there was no statistically significant difference between the intervention and control groups for 'Total length of ventilator days' (WMD) -2.00, 95% CI -18.36 to 14.36; and WMD 2.00, 95% CI -6.55 to 10.55 for the child and adult trials respectively). The studies used only proxies to measure long-term quality of life. There was a statistically significant reduction in the risk of requiring supplemental oxygen amongst survivors at 30 days in the paediatric study (RR 0.36, 95% CI 0.14 to 0.93). REVIEWER'S CONCLUSIONS: There is not enough evidence to conclude whether high-frequency ventilation reduces mortality or long-term morbidity in patients with ALI or ARDS; further trials are needed.

Adolescent↗
PubMed1996

Clinical evaluation of diminished early expiratory flow (DEEF) ventilation in mechanically ventilated COPD patients.

OBJECTIVE: To evaluate the cardiopulmonary effects, especially the end-expiratory lung volume (EEV) and ventilation inhomogeneity during diminished early expiratory flow ventilation (DEEF), which resembles pursed-lips breathing, with the conventional intermittent positive pressure ventilation (IPPV) in postoperative mechanically ventilated patients with chronic obstructive pulmonary disease (COPD). DESIGN: A prospective study measuring cardiopulmonary parameters during IPPV, DEEF, and positive end-expiratory pressure (PEEP) as a control mode. In the PEEP mode, PEEP values were chosen such that the mean airway pressure during a breath cycle was equal to that during the DEEF mode, which was higher than the conventional IPPV mode. SETTING: Surgical intensive care unit of a university hospital. PATIENTS: 20 postoperative mechanically ventilated COPD patients who were optimally pretreated and had normal blood oxygenation. INTERVENTIONS: Measurements were started in the IPPV (IPPV1) mode, continued in a randomized order with DEEF or PEEP, and completed with a second IPPV (IPPV2) mode, with 1 h equilibration time in each mode before each measurement. MEASUREMENTS AND RESULTS: A multi-breath indicator gas wash-out test was used to calculate the EEV and ventilation inhomogeneity. There was a 9% increase (p < 0.05) in the mean EEV during both the DEEF and PEEP mode compared to IPPV. No significant changes in the ventilation inhomogeneity and deadspace fractions or the hemodynamic parameters were found during the different ventilatory modes. CONCLUSIONS: There was no improvement in pulmonary and hemodynamic parameters during the DEEF mode in comparison to the IPPV mode. The small increase in EEV during DEEF was probably caused by the slightly higher mean expiratory pressures as in the PEEP mode. However, this had no effect on the hemodynamic parameters. As we could not observe any improvement with the DEEF ventilation in our optimally pretreated postoperative COPD patients, we do not advise applying this therapy in this group of patients, since this mode of ventilation may cause barotrauma if not monitored adequately.

Aged↗
PubMed1998

[Ventilation-perfusion distribution with volume-reduced, pressure-limited ventilation with permissive hypercapnia].

PURPOSE: Low volume pressure-limited ventilation with permissive hypercapnia (PH) may decrease the mechanical stress of the lung in acute respiratory insufficiency. Alveolar PCO2 is a determinant of regional ventilation, whereas increased mixed-venous and arterial PCO2 may affect systemic and pulmonary haemodynamics. The aim of this study was to analyse the ventilation-perfusion (VA/Q) distribution during controlled ventilation with permissive hypercapnia. METHODS: The study was approved by the ethical committee of the Ernst-Moritz-Arndt University of Greifswald. Eleven patients with severe ARDS (lung injury severity score 2.77 +/- 0.47) were studied. Intrapulmonary shunt (QS/QT, % of QT), lung areas with 0.005 < or = VA/Q < or = 0.1 ("low" VA/Q, % of QT), lung areas with 10 < or = VA/Q < or = 100 ("high" VA/Q, % of VE), dead space ventilation (VD/VT = VA/Q > 100, % of VE) and the mean distribution of ventilation (Vmean VA/Q) and perfusion (Qmean VA/Q) were determined by the multiple inert gas elimination technique during normocapnic (NC) and hypercapnic (HC) mechanical ventilation. In addition, systemic mean arterial and pulmonary arterial pressure, cardiac output (CO) and arterial and mixed venous partial pressures for oxygen (PaO2, PvO2) and carbondioxide (PaCO2, PvCO2) were assessed. RESULTS: Low-volume pressure-limited ventilation was associated with moderate hypercapnia (PaCO2 = 61 +/- 12 mmHg vs. 39 +/- 6 mmHg, p < 0.01). QS/QT increased (28 +/- 16% [NC] vs. 36 +/- 17% [HC], p < 0.05), whereas Qmean VA/Q decreased from 1.01 +/- 0.37 (NC) to 0.65 +/- 0.49 (HC), (p < 0.01) and Vmean VA/Q decreased from 1.54 +/- 0.58 (NC) to 1.12 +/- 0.93 (HC) (p < 0.05). Hypercapnia induced mild systemic hypotension and pulmonary hypertension. CO increased from 10.8 +/- 2.3 l/min to 11.6 +/- 2.6 l/min (p < 0.05). PaO2 was almost unchanged, but PvO2 increased significantly from 40 +/- 4 mmHg (NC) to 49 +/- 7 mmHg (HC) (p < 0.01). CONCLUSION: The mechanical ventilation with permissive hypercapnia may increase shunt due to alveolar derecruitement and an impaired hypoxic pulmonary vasoconstriction. PaO2 was unchanged due to an increased CO, PvO2 and--to a lesser extent--shift of the oxyhaemoglobin dissociation curve.

Adult↗