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PubMed1988

High frequency jet ventilation (HFJV) has no better haemodynamic tolerance than controlled mechanical ventilation (CMV) in cardiogenic shock.

Six patients with acute myocardial infarction (AMI) complicated by cardiogenic shock were studied in order to compare the haemodynamic tolerance of controlled mechanical ventilation (CMV) and high frequency jet ventilation (HFJV). The comparative analysis of the two techniques was performed with the same levels of PaO2 (CMV: 101 +/- 13 mmHg; HFJV: 104.2 +/- 14 p = ns); and PaCO2 (CMV: 37 +/- 1.7; HFJV: 35.7 +/- 1.4 p = ns). In this situation the values of mean airway pressure (Paw) did not differ significantly (CMV: 13 +/- 3 cm H2O; HFJV: 12.6 +/- 3.8 cm H2O) and no statistically significant difference in haemodynamic values was observed. These results demonstrate that in patients with cardiogenic shock, there is no difference between HFJV and CMV in terms of haemodynamic tolerance. Because of the more difficult clinical management of HFJV, this technique does not seem indicated as ventilatory support in patients with cardiogenic shock states.

Aged↗
PubMed1990

Auto-PEEP and dynamic hyperinflation in COPD patients during controlled mechanical ventilation and high frequency jet ventilation.

We investigated the levels of auto-PEEP and dynamic hyperinflation during high frequency jet ventilation (HFJV) and controlled mechanical ventilation (CMV) in six patients with chronic obstructive pulmonary disease within the first 36 h of acute exacerbation. The comparative evaluation was performed at similar conditions of gas exchange in HFJV and CMV: PaO2 77.6 +/- 11 mmHg vs 80.8 +/- 12 mmHg; PaCO2 46.8 +/- 2.5 mmHg vs 47 +/- 2.8 mmHg; pH 7.38 vs 7.38. In this situation, the values of auto-PEEP and dynamic hyperinflation, expressed as delta over the apneic functional residual capacity (FRC) did not differ: (auto-PEEPHFJV 8.9 +/- 3.8 cmH2O; auto-PEEPCMV 8.8 +/- 4.7 cmH2O; delta FRCHFJV 0.56 +/- 0.19 l; delta FRCCMV 0.54 +/- 0.2 l). This result suggests that, with a suitable machine setting and similar gas exchanges, HFJV produces the same level of auto-PEEP and dynamic hyperinflation as CMV in patients with chronic obstructive pulmonary disease.

Aged↗
PubMed1975

A modification of the Bird Mark VIII ventilator to deliver continuous positive pressure breathing and intermittent mandatory ventilation.

A Bird Mark VIII ventilator was modified to produce a simple and inexpensive C.P.P.B. and I.M.V. circuit. A Bain Breathing Circuit allowed the manifold to be placed near the ventilator. The negative pressure and flow to the injector produce C.P.P.B. The continuous flow of the Mapleson D Modification furnished constant inflow to provide humidified fresh gas to the reservoir and the patient circuit for I.M.V. An accompanying graph illustrates suggested flow rates and CO2 elimination (Figure 2).

Humans↗
PubMed2002

Protocol-directed weaning from mechanical ventilation: clinical outcome in patients randomized for a 30-min or 120-min trial with pressure support ventilation.

OBJECTIVE: To investigate the possibility of successful extubation performing a spontaneous breathing trial (SBT) in pressure support ventilation (PSV) with target durations of 30 and 120 min. DESIGN AND SETTING: Prospective and randomized study in two medical-surgical adult intensive care units. PATIENTS AND PARTICIPANTS: 98 adult patients supported by mechanical ventilation for at least 48 h and considered ready for a weaning trial. INTERVENTIONS: An SBT conducted in PSV with 7 cmH(2)O and patients randomly assigned to two groups with target durations of 30- and 120-min. MEASUREMENTS AND RESULTS: In the 30-min group 43 patients (93%) tolerated the SBT and were extubated while 4 (9%) needed reintubation within 48 h; in the 120-min group 46 patients (88%) successfully completed the trial and were extubated while 2 (4%) were reintubated. ICU mortality in the groups with short and long periods was 6% and 4%, and in-hospital mortality 20% and 17%, respectively. Those successful in the 30- and 120-min groups had similar length of ICU stay (6 and 7 days, respectively) and in-hospital length of stay (20 and 25 days, respectively). Compared to the successfully extubated, the reintubated patients had significantly higher length of ICU stay and mortality (17 vs. 6 days and 33 vs. 3.6%, respectively). CONCLUSIONS: An SBT with PSV of 7 cmH(2)O lasting 30 min is equally effective in recognizing the successfully extubated patients as a 120-min trial.

Aged↗
PubMed2002

Comparison of the effects of heat and moisture exchangers and heated humidifiers on ventilation and gas exchange during non-invasive ventilation.

OBJECTIVE: To compare the short-term effects of a heat and moisture exchanger (HME) and a heated humidifier (HH) during non-invasive ventilation (NIV). DESIGN: Prospective, clinical investigation. SETTING: Intensive care unit of a university hospital. PATIENTS: Twenty-four patients with acute respiratory failure (ARF). INTERVENTION: Each patient was studied with a HME and a HH in a random order during two consecutive 20min periods of NIV. MEASUREMENTS AND RESULTS: Respiratory rate (RR), expiratory tidal volume (VTe) and expiratory minute ventilation (VE) were measured during the last 5 min of each period and blood gases were measured. Mean pressure support and positive end-expiratory pressure levels were, respectively, 15+/-4 and 6+/-2 cmH(2)O. VE was significantly greater with HME than with HH (14.8+/-4.8 vs 13.2+/-4.3 l/min; p<0.001). This increase in VE was the result of a greater RR for HME than for HH (26.5+/-10.6 vs 24.1+/-9.8 breaths/min; p=0.002), whereas the VT for HME was similar to that for HH (674+/-156 vs 643+/-148 ml; p=0.09). Arterial partial pressure of carbon dioxide (PaCO(2)) was significantly higher with a HME than with a HH (43.4+/-8.9 vs 40.8+/-8.2 mmHg; p<0.005), without significantly changing oxygenation. CONCLUSION: During NIV the increased dead space of a HME can negatively affect ventilatory function and gas exchange. The effect of HME dead space may decrease efficiency of NIV in patients with ARF.

Acute Disease↗
PubMed2003

Comparative effects of helium-oxygen and external positive end-expiratory pressure on respiratory mechanics, gas exchange, and ventilation-perfusion relationships in mechanically ventilated patients with chronic obstructive pulmonary disease.

OBJECTIVE: To compare the effects of He/O(2) and external PEEP (PEEPe) on intrinsic PEEP (PEEPi), respiratory mechanics, gas exchange, and ventilation/perfusion (V(A)/Q) in mechanically ventilated COPD patients. DESIGN AND SETTING: Prospective, interventional study in the intensive care unit of a university hospital. INTERVENTIONS: Ten intubated, sedated, paralyzed, mechanically ventilated COPD patients studied in the following conditions: (a) baseline settings made by clinician in charge, air/O(2), ZEEP; (b) He/O(2), ZEEP; (c) air/O(2), ZEEP; (d) air/O(2), PEEPe 80% of PEEPi. Measurements at each condition included V(A)/Q by the multiple inert gas elimination technique (MIGET). RESULTS: PEEPi and trapped gas volume were comparably reduced by He/O(2) (4.2+/-4 vs. 7.7+/-4 cmH(2)O and 98+/-82 vs. 217+/-124 ml, respectively) and PEEPe (4.4+/-1.3 vs. 7.8+/-3.6 cmH(2)O and 120+/-107 vs. 216+/-115 ml, respectively). He/O(2) reduced inspiratory and expiratory respiratory system resistance (15.5+/-4.4 vs. 20.7+/-6.9 and 19+/-9 vs. 28.8+/-15 cmH(2)O l(-1)s(-1), respectively) and plateau pressure (13+/-4 vs. 17+/-6 cmH(2)O). PEEPe increased airway pressures, including total PEEP, and elastance. PaO(2)/FIO(2) was slightly reduced by He/O(2) (225+/-83 vs. 245+/-82) without significant V(A)/Q change. CONCLUSIONS: He/O(2) and PEEPe comparably reduced PEEPi and trapped gas volume. However, He/O(2) decreased airway resistance and intrathoracic pressures, at a small cost in arterial oxygenation. He/O(2) could offer an attractive option in COPD patients with PEEPi/dynamic hyperinflation.

Aged↗
PubMed2006

Effect of high-frequency jet ventilation on oxygenation during one-lung ventilation in patients undergoing thoracic aneurysm surgery.

PURPOSE: To evaluate the effect of high-frequency jet ventilation (HFJV) and continuous positive airway pressure (CPAP) on oxygenation and the shunt fraction (Qs/Qt) during one-lung ventilation (OLV). METHODS: Twenty-five patients who were undergoing resection of a descending aortic aneurysm were studied. Arterial oxygenation, Qs/Qt, and hemodynamics were evaluated just before the initiation of OLV (T1), 15 min after OLV (T2), and 15 min (T3) and 30 min (T4) after the application of HFJV or CPAP to the nondependent lung. RESULTS: There were no significant changes in the mean arterial blood pressure (MAP), heart rate (HR), central venous pressure (CVP), or mixed venous partial pressure of oxygen throughout this study. The arterial partial pressure of oxygen (Pa(O2)) values after the application of HFJV or CPAP increased significantly, from 173.8 +/- 39.6 mmHg (T2) to 344.1 +/- 87.9 mmHg (T3) and 359.9 +/- 82.4 mmHg (T4) in the HFJV group (P < 0.05), and from 153 +/- 38.5 mmHg (T2) to 243 +/- 48.5 mmHg (T3) and 249.7 +/- 55.0 mmHg (T4) in the CPAP group (P < 0.05). The shunt fraction decreased significantly after the initiation of HFJV or CPAP, from 38.7% +/- 8.9% (T2) to 27.0% +/- 8.0% (T3) and 25.9% +/- 8.7% (T4) in the HFJV group (P < 0.05), and from 44.6% +/- 8.6% (T2) to 34.3% +/- 10.2% (T3) and 32.6% +/- 8.5% (T4) in the CPAP group (P < 0.05). The arterial saturation of oxygen (Sa(O) (2)) increased significantly after the application of either HFJV or CPAP (P < 0.05). CONCLUSIONS: Both HFJV and CPAP can improve oxygenation during OLV.

Adult↗
PubMed1989

Odor volatiles associated with microflora in damp ventilated and non-ventilated bin-stored bulk wheat.

Western hard red spring wheat, stored at 20 and 25% moisture contents for 10 months during 1985-86, was monitored for biotic and abiotic variables in 10 unheated bins in Winnipeg, Manitoba. The major odor volatiles identified were 3-methyl-1-butanol, 3-octanone and 1-octen-3-ol. The production of these volatiles was associated and correlated with microfloral infection. Ventilation, used for cooling and drying of grain, disrupted microfloral growth patterns and production of volatiles. The highest levels of 3-methyl-1-butanol occurred in 25% moisture content wheat infected with bacteria, Penicillium spp. and Fusarium spp. In non-ventilated (control) bins with 20% moisture content wheat, 3-methyl-1-butanol was correlated with infection by members of the Aspergillus glaucus group and bacteria. In control bins, 1-octen-3-ol production was correlated with infection of wheat of both moisture contents by Penicillium spp. The fungal species, isolated from damp bin-stored wheat and tested for production of odor volatiles on wheat substrate, included Alternaria alternata (Fr.) Keissler, Aspergillus repens (Corda) Saccardo, A. flavus Link ex Fries, A. versicolor (Vuill.) Tiraboschi, Penicillium chrysogenum Thom, P. cyclopium Westling, Fusarium moniliforme Sheldon, F. semitectum (Cooke) Sacc. In the laboratory, fungus-inoculated wheat produced 3-methyl-1-butanol; 3-octanone and 1-octen-3-ol were also produced, but less frequently. Two unidentified bacterial species isolated from damp wheat and inoculated on agar produced 3-methyl-1-butanol.

Alcohols↗
PubMed1990

High-frequency oscillatory ventilation compared with conventional intermittent mechanical ventilation in the treatment of respiratory failure in preterm infants: neurodevelopmental status at 16 to 24 months of postterm age. The HIFI Study Group.

The High-Frequency Intervention Trial was a 10-center randomized clinical trial to test the efficacy and safety of high-frequency oscillatory ventilation (HFO) in the treatment of neonates weighing 750 to 2000 gm; 327 infants were assigned to HFO and 346 to conventional intermittent mechanical ventilation (IMV). Survival and lung morbidity rates were the same in the two groups. Bayley psychometric evaluations and CNS examination were performed at 16 to 24 months of postterm age in 77% of the survivors (185 HFO and 201 IMV). There was no difference in growth or respiratory status at follow-up. Cerebral palsy was diagnosed in 19 (10%) HFO-treated infants and 23 (11%) IMV-treated infants. There was no difference in severity between the two groups. A significantly higher incidence of hydrocephalus (12% vs 6%) was present in the HFO group (p less than 0.05). Bayley index scores greater than 83 were scored in 57% of HFO-treated infants compared with 66% of IMV-treated infants. The proportion of children at follow-up with a normal neuro-developmental status (i.e., Bayley score greater than 83 and no major CNS defect) was significantly less in the HFO than in the IMV group (54 vs 65%; p less than 0.05). Both treatment groups showed a strong association between the presence of grade 3 or 4 intraventricular hemorrhage and the development of major CNS or cognitive defects. No significant long-term beneficial or deleterious effects were demonstrated in the use of HFO versus IMV for the treatment of respiratory failure in low birth weight premature infants, except that there were slightly more neurologic deficits in the HFO group related to the higher proportion of survivors with major intraventricular hemorrhage.

Cerebral Hemorrhage↗
PubMed1994

Randomised trial of preventive nasal ventilation in Duchenne muscular dystrophy. French Multicentre Cooperative Group on Home Mechanical Ventilation Assistance in Duchenne de Boulogne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy in children. Paralysis of respiratory muscles causes a decrease in forced vital capacity (FVC) from age 12 years, and death occurs between 20 and 25 years old and is usually related to respiratory insufficiency. Uncontrolled studies suggest that early home use of nasal intermittent positive-pressure ventilation (NIPPV) in DMD patients free of respiratory failure could limit progression of the restrictive syndrome and therefore improve survival because efficacy of preventive NIPPV has not been demonstrated in a controlled trial, we undertook a randomised multicentre study in which 70 patients with DMD were included. Patients were free of daytime respiratory failure and FVC was between 20 and 50% of predicted values. At least 6 h of nocturnal NIPPV (n = 35) was compared with conventional treatment (n = 35). During a mean follow-up of 52 months, 10 patients died, 8 in the NIPPV group and 2 in the control group (p = 0.05, log-rank test). No differences were observed between the two groups for occurrence of hypercapnia, decrease of FVC below 20% of initial values, or use of necessary mechanical ventilation. Preventive NIPPV did not improve respiratory handicap and reduced survival of DMD patients. Use of NIPPV for preventive purposes should be avoided in patients with FVC between 20 and 50% of predicted values.

Adolescent↗
PubMed1998

The ventilator: selection of mechanical ventilators.

A comprehensive ventilator selection process can be a time-consuming and an overwhelming task. The needs assessment becomes the primary driving tool in the design of the selection process. From the needs assessment, the evaluation can be planned and organized according to the facility requirements, time constraints, and resources. The strategy can expand to an extensive project or have a succinct and condensed design. The needs assessment determines the criteria for the selection, whether it be cost, ventilator specifications, educational needs, manufacturer support needs, maintenance requirements, accessory items, or combinations of any item. Once the data have been collected, it must be analyzed and critiqued. How this examination is performed can be expansive or scaled down according to the facility's resources. Important items in the selection must be maintained and used more extensively in the decision, whereas less important items take a backseat in the operation. The final selection comes from the culmination of the entire process.

Equipment Design↗
PubMed2001

Elimination of mouse allergens in the working environment: assessment of individually ventilated cage systems and ventilated cabinets in the containment of mouse allergens.

BACKGROUND: Laboratory animal allergy is an important occupational disease that is preventable by reduction of exposure to mammalian allergens. OBJECTIVE: The purpose of this investigation was to assess the efficacy of safety equipment in containing mouse urinary protein (MUP)--specifically, individually ventilated cage (IVC) systems and class I--type and class II ventilated cabinets. METHODS: Six IVC systems (which are used to house rodents) were operated at positive and negative pressure. Air samples (2 L/min) were collected at the cage front, cage back, air inlet, and air outlet, and the MUP was quantified by immunoassay. The background MUP of the IVC study room was compared with that of rooms where mice were housed conventionally or in isolators. Class I--type cabinets (n = 2) were tested during the disposal of soiled litter. Air samples were positioned on and behind the operator and inside the cabinet (n = 2). Personal samples were collected while scientific procedures were performed in a class II cabinet and in the open. RESULTS: All of the IVC systems contained MUP effectively (>250-fold) when operated at negative pressure. At positive pressure, the "unsealed" IVC racks leaked MUP (1- to 25-fold reduction) but the "sealed" IVC system did not. Class I--type cabinets reduced (10-fold) but did not eliminate exposure during "cleaning out." No MUP was detected when procedures were performed in class II cabinets (protection factor, >10-fold). CONCLUSION: Safety equipment can substantially reduce exposure to mouse allergen. Allergen exposure in holding rooms will be minimized if mice are housed in IVC systems operated at negative pressure or in "sealed" IVC systems at positive pressure. Respiratory protection should be used whenever "unsealed" IVC systems are operated at positive pressure or during "cleaning out" in class I--type cabinets.

Allergens↗
PubMed2003

Randomized trial of high-frequency oscillatory ventilation versus conventional ventilation: effect on systemic blood flow in very preterm infants.

OBJECTIVE: Low superior vena cava (SVC) flow is common in very preterm infants in the first day and strongly associated with periventricular hemorrhage and disability. We examined the effect of high-frequency oscillatory ventilation (HFOV) compared with conventional ventilation (CV) on SVC flow and right ventricular output. METHODS: Forty-five infants <29 weeks were randomized before 1 hour of age to HFOV or CV. Echocardiography was performed on 43 infants at 3, 10, and 24 hours of age. Infants with low SVC flow (<50 mL/kg/min) or hypotension (mean blood pressure < or =20) were treated with volume and inotrope. RESULTS: Infants allocated to HFOV (n=23) and to CV (n=20) were well matched. There was a nonsignificant trend toward more infants on HFOV having SVC flow <50 mL/kg/min (48% vs 20%) and receiving volume and inotropes (61% vs 40%). There were no significant differences in mean SVC flow or right ventricular output at 3, 10, or 24 hours. Infants on HFOV had a significantly higher calculated upper body vascular resistance at 10 hours and mean blood pressure at 24 hours. CONCLUSIONS: There were no significant adverse effects of HFOV on systemic blood flow in very preterm infants during the first 24 hours of life.

Blood Circulation↗
PubMed1984

Effect of frequency of ventilation, positive end-expiratory pressure, PaO2 and PaCO2 on phrenic nerve activity. A study using a new valveless all-purpose ventilator.

The effect of changing the frequency of ventilation from 12 b.p.m. (NFV) to 80 b.p.m. (HFV) and applying PEEP on phrenic nerve activity (PNA) has been examined in anaesthetized dogs. HFV did not cause a greater decrease in PNA than the application of 0.5 kPa of PEEP. When the PEEP generated by HFV was removed by applying NEEP, PNA returned to control values. At a low normal PaCO2 (less than 5.3 kPa) and high PaO2 (greater than 30 kPa), HFV and PEEP (0.5 kPa) totally abolished PNA in some preparations. With a high normal PaCO2 (greater than 6.0 kPa) and high PaO2 (greater than 30 kPa), HFV and PEEP (0.5 kPa) decreased PNA by a mean of only 30%. When PaO2 was decreased to physiological values (less than 13.3 kPa), with a low normal PaCO2 (less than 5.3 kPa), the decrease in PNA by HFV and PEEP (0.5 kPa) was decreased to 25%. It was concluded that the frequency of ventilation per se has little or no effect on PNA in the range of frequencies studied.

Animals↗
PubMed1985

Arterial to end-tidal CO2 gradients during spontaneous breathing, intermittent positive-pressure ventilation and jet ventilation.

Arterial to end-tidal CO2 tension gradients were measured in 18 dogs during spontaneous breathing (SB), intermittent positive-pressure ventilation (IPPV), and both low-frequency and high-frequency jet ventilation (LFJV and HFJV). The dogs were anesthetized with nembutal and permitted to breathe spontaneously through an 8-mm internal diameter endotracheal tube; blood gas tensions, cardiac output, and end-tidal CO2 partial pressure (PetCO2) were measured. IPPV, LFJV, and HFJV were then instituted in a random sequence and measurements repeated. PaO2, PaCO2 and cardiac output were similar during all four ventilatory modes. The mean PaCO2 differed significantly (p less than .001) from PetCO2 during IPPV, LFJV, and HFJV but not during SB. The mean PaCO2-PetCO2 gradient was 3.7 +/- 1 (SD), 12.6 +/- 5.0, and 24.3 +/- 8 torr during IPPV, LFJV and HFJV, respectively. The large gradients during LFJV and HFJV were not produced by dilution of tracheal CO2 by entrained air or by oxygen delivered by the jet. These results suggest that both LFJV and HFJV may be associated with a large PaCO2-PetCO2 gradient.

Animals↗
PubMed2000

Mechanical ventilation with high positive end-expiratory pressure and small driving pressure amplitude is as effective as high-frequency oscillatory ventilation to preserve the function of exogenous surfactant in lung-lavaged rats.

OBJECTIVE: To demonstrate that under well-defined conditions, pressure-controlled ventilators (PCV) allow settings that are as good as high-frequency oscillatory ventilators (HFOV) at preserving the function of exogenous surfactant in lung-lavaged rats. DESIGN: Experimental, comparative study. SETTING: Research laboratory of a large university. SUBJECTS: Sixteen adult male Sprague-Dawley rats (280-310 g). INTERVENTIONS: Lung injury was induced by repeated lavage. After last lavage, all animals received exogenous surfactant and were then randomly assigned to two groups (n = 8 per group). The first group received PCV with small pressure amplitudes and high positive end-expiratory pressure. The second group received HFOV. In both groups, an opening maneuver was performed by increasing airway pressure to improve PaO2/F(IO2) to > or =500 torr. MEASUREMENTS AND MAIN RESULTS: Blood gases were measured every 30 mins for 3 hrs. Airway pressures were measured with a tip catheter pressure transducer. At the end of the study period, a pressure-volume curve was recorded and a broncho-alveolar lavage was performed to determine protein content and surfactant composition. The results showed that arterial oxygenation in both groups could be kept >500 torr during the 3-hr study period by using a mean airway pressure of 13+/-3 cm H2O in PCV and 13+/-2 cm H2O in HFOV. Further, there were no differences in the Gruenwald index, protein influx, or ratio of small to large aggregates between the study groups. CONCLUSION: PCV with sufficient level of positive end-expiratory pressure and small driving pressure amplitudes is as effective as HFOV to maintain optimal gas exchange, to improve lung mechanics, and to prevent protein influx and conversion of large into small aggregates after exogenous surfactant therapy in lung-lavaged rats.

Animals↗