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At least 433 records · Page 24Linked to original sources
PubMed1999

Failure of exhalation during ventilation with the Dräger Oxylog 2000 ventilator.

We describe three cases in which there was failure of exhalation during mechanical ventilation with the Dräger Oxylog 2000 ventilator. Two potential mechanisms for this failure were identified, and were then experimentally reproduced on a test lung. First, a manufacturing fault in the silicone diaphragm in the ventilation valve was discovered. When a small hole in the diaphragm was incompletely perforated, a possible flap valve was formed, limiting exhalation. Second, failure of the one-way rubber disc valve to seat properly in its housing also prevented exhalation. These two previously unreported modes of ventilator failure have been identified. Careful checking of the ventilator circuit before each use is required.

Aged↗
PubMed1976

[Artificial ventilation with the servo-ventilator 900 (author's transl)].

The use of artificial ventilation in the treatment of seriously ill or severely injured patients demands extensive knowledge on the part of the physician of the physiological and pathological effects of ventilation. In addition, it is required that the manufacturers develop ventilators able to meet there special demands. During the last two years the Servo-Ventilator 900 has been in use in our intensive care unit. During this period we were very impressed by its versatile applicability. The use of this apparatus however more than ever before requires the knowledge of breathing mechanisms and their pathophysiological consequences. The various flow- and breathing-rate-patterns combined with the exact electronic control of the respiratory make possible subtle adjustments--to the required ventilation pattern.

Humans↗
PubMed2001

Minute ventilation-sensor driven pacemaker related difficulty in weaning from mechanical ventilation: a case report.

BACKGROUND: Minute ventilation responsive rate adaptive pacemaker improves exercise performance in the patients with chronotropic insufficiency. The usual complications of these pacemakers are related to pacemaker implantation, rather than to the rate adaptive function. CASE REPORT: We report a patient with mitral stenosis and atrial fibrillation with a VVIR pacemaker, who was mechanically ventilated for respiratory failure. The patient could not be weaned because of the minute ventilation driven increased heart rates. Subsequently the rate adaptive function was switched off and the patient was successfully weaned from ventilator. CONCLUSIONS: Difficulty in weaning from mechanical ventilation can be a serious complication in patients with organic heart disease, who depend on diastolic filling time for adequate cardiac output.

Aged↗
PubMed2001

[Effects of a pressure support ventilation of 6 cm H2O on oxygen consumption of the respiratory muscles during weaning of mechanical ventilation].

OBJECTIVE: To determine the effects of a pressure support ventilation (PSV) of 6 cm H(2)O during spontaneous breathing on oxygen consumption of the respiratory muscles (VO(2) resp), gas exchange, respiratory rate, tidal volume and to determine if these low levels of PSV can reduce or cancel the increase in work of breathing induced by the resistances of the endotracheal tube and the circuit of the respirator. PATIENTS AND METHODS: Prospective study. Twenty intubated patients were studied. The VO(2) resp was assessed by measurements of inspired and expired concentrations of oxygen (O(2)) and carbon dioxide (CO(2)) in patients during controlled ventilation and spontaneous breathing. Gas exchange, respiratory rate, minute ventilation, tidal volume and VO(2) resp were collected during spontaneous breathing with a PSV level of 6 cm H(2)O and without PSV. SETTING: Respiratory Intensive Care Unit, Amiens, University Hospital 80054 Amiens. RESULTS: A PSV level of 6 cm H(2)O significantly increased the spontaneous tidal volume (+12%) without any modification in respiratory rate, minute ventilation, tidal volume and gas exchange. No significant improvement in VO(2) resp was found when a PSV level of 6 cm H(2)O was added. CONCLUSION: Despite a significant increase in spontaneous tidal volume, adding a PSV level of 6 cm H(2)O did not improve VO(2) resp. Thus, low level of PSV did not reduce the increased work of breathing induced by the resistances of the ventilator tubing and the endotracheal tube.

Adult↗
PubMed2003

Care of the ventilator circuit and its relation to ventilator-associated pneumonia.

Ventilator circuits should not be changed routinely for infection control purposes. The maximum duration of time that circuits can be used safely is unknown. Evidence is lacking related to ventilator-associated pneumonia (VAP) and issues of heated versus unheated circuits, type of heated humidifier, method for filling the humidifier, and technique for clearing condensate from the ventilator circuit. Although the available evidence suggests a lower VAP rate with passive humidification than with active humidification, other issues related to the use of passive humidifiers (resistance, dead space volume, airway occlusion risk) preclude a recommendation for the general use of passive humidifiers. Passive humidifiers do not need to be changed daily for reasons on infection control or technical performance. They can be safely used for at least 48 hours, and with some patient populations some devices may be able to be used for periods of up to 1 week. The use of closed suction catheters should be considered part of VAP prevention strategy, and they do not need to be changed daily for infection control purposes. The maximum duration of time that closed suction catheters can be used safely is unknown. Clinicians caring for mechanically ventilated patients should be aware of risk factors for VAP (eg, nebulizer therapy, manual ventilation, and patient transport).

Humans↗
PubMed2004

Randomized prospective crossover study of biphasic intermittent positive airway pressure ventilation (BIPAP) versus pressure support ventilation (PSV) in surgical intensive care patients.

BACKGROUND AND OBJECTIVE: The aim of this prospective, randomized and crossover study was to assess the role of a relatively new mode of mechanical ventilation, biphasic intermittent positive airway pressure (BIPAP) in comparison to another well established one, pressure-support ventilation (PSV) in surgical intensive care patients. METHODS: 24 generally stable patients, breathing on their own after short-term (< 24 hours) postoperative controlled mechanical ventilation (CMV) were randomized to start on either PSV or BIPAP, and indirect calorimetry measurements were performed after 1 hour adaptation period at two time intervals; immediately after the investigated ventilatory mode was started and 1 hour later. Statistics included a two-tailed paired t-test to compare the two sets of different data, p < 0.5 was considered significant. RESULTS: Oxygen consumption (VO2), energy expenditure (EE), Carbon dioxide production (VCO2), and respiratory quotient (RQ) did not differ significantly between the two groups. There were also no significant differences regarding respiratory rate (RR), minute volume (MV) and arterial blood gas analysis (ABGs). Both modes of ventilation were well tolerated by all patients. CONCLUSION: PSV and BIPAP can be used for weaning patients comfortably in surgical intensive care after short-term postoperative ventilation. BIPAP may have the credit of being smoother than PSV where no patient effort is required.

Aged↗
PubMed1990

[The tidal volume, arterial blood gas and functional residual capacity changes during negative extra-thoracic pressure ventilation and positive airway pressure ventilation].

Eight patients, of ASA physical status I or II soon after total knee replacement under general anesthesia, were studied to compare negative extra-thoracic pressure ventilation (NETPV) with positive airway pressure ventilation (PAPV). The measured parameters during the two ventilatory modes were tidal volume, arterial blood gas and functional residual capacity change (delta FRC). Tidal volume obtained during NETPV was 60 to 80% of that during PAPV at the same absolute values of peak pressure. delta FRC obtained during NETPV was 30 to 40% of that during PAPV at the same absolute values of end-expiratory pressure. A decrease in the esophageal pressure was 4 to 11cmH2O at an end-expiratory negative extra-thoracic pressure of -10 to -20 cmH2O. When the patients were ventilated with the same values of minute ventilation on NETPV and PAPV, there was no significant difference in blood gas values. These findings suggest that efficiency of NETPV is less than that of PAPV at the same absolute working pressure but pulmonary gas exchange of NETPV is almost equal to that of PAPV at the same minute ventilation in the normal lung.

Aged↗
PubMed1988

[Periodic nocturnal ventilation using an Emerson chest respirator as an alternative to permanent tracheostomy with positive pressure ventilation in patients with idiopathic scoliosis and severe global respiratory insufficiency].

Sustained success was achieved in treating a 40-year-old patient who had had severe progressive thoracic kyphoscoliosis since childhood and developed cardiorespiratory failure with terminal alveolar hypoventilation and hypoxemia due to acute pulmonary infection. On emergency admission to this hospital mechanically controlled ventilation by tracheostomy tube produced a remarkable improvement in cardiorespiratory function. Weakness of the respiratory muscles made complete disconnection from ventilatory support impossible. Instead of positive pressure ventilation by tracheostomy tube with resultant patient invalidity, nighttime external negative pressure ventilation with an Emerson chest respirator was started leaving the patient free for daytime activity. This type of ventilation is a simple, effective and well tolerated long-term treatment at low cost. The patient has been using it nightly at home for over 6 months and no problems have arisen. These findings show that intensive care is indicated in patients with severe thoracic kyphoscoliosis and cardiorespiratory failure since long-term treatment of terminal hypoventilation and cardiorespiratory failure is possible with a cheap and simple nocturnal ventilation system.

Adult↗
PubMed1986

Intermittent positive pressure ventilation with either positive end-expiratory pressure or high frequency jet ventilation (HFJV), or HFJV alone in human acute respiratory failure.

Continuous Positive Pressure Ventilation (CPPV), High-Frequency Jet Ventilation (HFJV), and a combination of HFJV with Intermittent Positive Pressure Ventilation (CV) were randomly compared in 13 critically ill patients with severe acute respiratory failure. Ventilatory settings were chosen in order to apply the same mean airway pressure (Paw) during the three modes. Respiratory frequencies were adjusted during CPPV (16 +/- 2 breaths/min) and HFJV (235 +/- 32 breaths/min) to achieve the same level of PaCO2 and were then combined during CV. All patients were heavily sedated during the study and had had peripheral and balloon-tipped pulmonary arterial catheters previously inserted. After a steady state at FIO2 1 in each mode of ventilation, hemodynamic and respiratory parameters were measured. A Paw of 13.8 +/- 2.9 mm Hg was applied to each patient by using a PEEP of 7.4 mm Hg during CPPV; a driving pressure of 2.9 +/- 0.2 bars and an I/E ratio of 0.43 during HFJV; and by combining HFJV, using a driving pressure of 1.2 +/- 0.3 bars with intermittent positive pressure ventilation during CV. There were no significant differences in any of the hemodynamic or respiratory parameters measured, except for a significant decrease in PaCO2 during CV when compared to CPPV or HFJV. We concluded that 1) arterial oxygenation and cardiac output depend mainly on Paw independent of the method used to increase Paw and 2) CV can improve CO2 elimination without increasing Paw.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

Bronchoscopic findings in infants treated with high-frequency jet ventilation versus conventional ventilation.

To identify tracheobronchial abnormalities associated with assisted ventilation, 40 infants with respiratory distress syndrome randomized to receive either short-term (48 hours) conventional or high-frequency jet ventilation were studied. Flexible fiberoptic bronchoscopy (n = 13) was performed and/or clinical and radiographic assessments were used to evaluate for laryngeal, tracheal, and bronchial lesions. There was no bronchoscopic evidence of necrotizing tracheobronchitis after either high-frequency jet ventilation (n = 8) or conventional ventilation (n = 5). Laryngotracheomalacia and nodular vocal cords were the most common abnormalities noted, and they occurred with equal frequency in both groups. Study infants who were not bronchoscoped had no clinical or radiographic evidence of tracheal or mainstem bronchial obstruction. One patient did have microscopic evidence of necrotizing tracheobronchitis at autopsy, however. It is concluded that short-term treatment of respiratory distress syndrome with high-frequency jet ventilation may be performed without undue risk of tracheobronchial injury.

Bronchi↗
PubMed1984

Cerebral and cardiopulmonary responses to high-frequency jet ventilation and conventional mechanical ventilation in a model of brain and lung injury.

The cardiopulmonary and intracranial effects of high-frequency jet ventilation (HFJV) were evaluated in four groups of 10 mongrel dogs and compared to conventional mechanical ventilation with and without positive and expiratory pressure (PEEP). Each group of animals was studied with various combinations of normal and abnormal brain and lung function. Experimental brain injury (abnormal cerebral elastance) was produced by infusion of saline into the subarachnoid space to increase intracranial pressure (ICP), while lung injury resulted from intratracheal instillation of 0.1N HCl. Animals responded similarly to HFJV and conventional ventilation except for those with abnormal lungs, in whom peak airway pressures were significantly lower with HFJV (P less than 0.05). The application of PEEP (10 and 20 cm H2O) produced significant increases in mean airway pressure compared to HFJV (P less than 0.05). Animals with abnormal lungs demonstrated significantly improved mean PaO2 (194 vs 104 mm Hg) and shunt fraction (0.20 vs 0.45) with 20 cm H2O PEEP compared to HFJV. In all dogs subjected to 20 cm H2O PEEP, cardiac index and mean arterial pressure were decreased significantly (P less than 0.05) below values with HFJV. ICP responses did not vary significantly with the different modes of ventilation and were not influenced by the status of lung or brain function. However, significant reductions in cerebral perfusion pressure were noted with 20 cm H2O PEEP compared to HFJV. We conclude that unless high levels of PEEP (15-20 cm H2O) are required for adequate oxygenation, the cardiovascular and cerebral effects of HFJV do not differ significantly from those of conventional mechanical ventilation.

Airway Resistance↗
PubMed1988

High-frequency oscillatory ventilation combined with intermittent mandatory ventilation in critically ill neonates: 3 years of experience.

A heterogeneous group of 45 neonates with severe pulmonary disease and inadequate gas exchange on conventional intermittent mandatory ventilation (IMV) was treated with a high-frequency oscillator combined with an IMV (HFO-IMV) system (Emerson Airway Vibrator connected to a BABYBird 1 ventilator). The mean gestational age was 33 weeks (25.5-43) and mean birth weight 2.02 kg (0.66-4.24). Primary diagnoses included respiratory distress syndrome (RDS; 23), pneumonia (12), persistent fetal circulation (PFC; 6), diaphragmatic hernia/hypoplastic lungs (4). The IMV rate was reduced from 78 to 29 BPM (P less than or equal to 0.0005), while maintaining lower partial pressure of carbon dioxide (PaCO2) (P less than 0.005) and higher partial pressure of oxygen (PaO2) (P less than or equal to 0.0025). Active air leaks were present in 20 infants and these infants responded most favourably to HFO-IMV. HFO-IMV failed to improve ventilation in neonates with diaphragmatic hernia/hypoplastic lungs. Complications during HFO-IMV were increased pulmonary secretions (11), worsening or recurrence of pre-existing air leaks (11), or occurrence of new air leaks (10). In 4 patients death was related to major air leak complications. Twenty-four infants died, 18 of them of a respiratory cause. Twenty-one infants finally survived. We assembled a well-tolerated system to provide HFO-IMV and to successfully ventilate neonates with severe respiratory disease, who failed to respond to conventional IMV. Initiation of HFO-IMV earlier in the course of the disease in this type of infant may improve survival.

Female↗
PubMed1991

Effects of endotracheal tube size and ventilator settings on the mechanics of a test system during intermittent flow ventilation.

The effect of varying the size of standard neonatal endotracheal tubes on delivered tidal volumes (VT), resistance (R), dynamic compliance (Cdyn), and resistive work of breathing (WOB) was measured in a test system during intermittent flow ventilation at different ventilator settings. The experiments were performed with a Sechrist infant ventilator connected to a Dräger Test Lung via standard neonatal endotracheal tubes. R, inspiratory (Ri), and expiratory resistance (Re) as well as WOB were significantly affected by endotracheal tube size. The calculated difference in Re between endotracheal tubes of 2.5 and 3.5 mm I.D. was 93 cm H2O/L/S (mean value for all studies). Cdyn and VT were also affected by endotracheal tube size. However, although statistically significant differences were found in Cdyn (mean, 0.584 mL/cm H2O and 0.567 mL/cm H2O) and VT (mean, 13.0 mL and 12.7 mL) for the tube sizes 3.5 mm and 2.5 mm I.D., respectively, the absolute numerical differences were small. Also, ventilator settings with respect to the peak inspiratory pressure (PIP) - positive end-expiratory pressure (PEEP) difference had a significant influence on Cdyn for both tube sizes. On the other hand, flow and inspiratory time adjustments had no significant effect on ventilatory parameters. Endotracheal tube size and ventilator settings should be considered when comparing the pulmonary function tests in intubated and non-intubated newborn infants.

Airway Resistance↗
PubMed1987

Comparison of high-frequency jet ventilation to conventional ventilation in adults with respiratory distress syndrome.

Sixteen patients with acute respiratory failure (ARF) were studied. In group I (12 patients, 15 explorations) patients were treated with continuous positive pressure ventilation (CPPV) during conventional ventilation (CV), pulmonary lesions (PL) were severe (Qsp/Qt = 0.24 +/- 0.16 with PEEP = 14 +/- 7 cm H2O) and high-frequency jet ventilation (HFJV) was performed without spontaneous ventilation (SV). In group II (5 patients, 12 explorations) patients were treated with intermittent mandatory ventilation (IMV) during CV, PL were moderate (Qsp/Qt = 0.13 +/- 0.05 with PEEP = 8 +/- 3 cm H2O) and HFJV was performed with SV. In both groups, frequency was 120 c/mn and I:E ratio = 1:2. The cannula size, the driving pressure and the PEEP (water column) were progressively adapted to obtain the same blood gases as those observed during CV, FIO2 being the same. Results on HFJV were compared to CV. In both groups there were no differences between PaCO2, PaO2, FIO2, Qsp/Qt during CV and HFJV. In group I peak airway pressure (PAWP), mean artery pressure (MAP), heart rate (HR), transmural mean pulmonary and wedge pressure (MPAPtm, PWPtm) were not different. Mean airway pressure (MAWP), PEEP and pleural pressure (PP) were higher, cardiac index (CI) was lower. In group II, PP, CI, MAP, HR, MPAPtm, MPWPtm were not different. PAWP was lower, MAWP and PEEP were higher. We conclude that during HFJV it is possible to obtain the same blood gas as during CV, but HFJV without CV may not be indicated in patients with severe PL, because circulatory impairment is higher.

Adult↗
PubMed1989

Comparison of pressure support ventilation and assist control ventilation in patients with acute respiratory failure.

We compared the effects of pressure support ventilation (PSV) with those of assist control ventilation (ACV) on the breathing pattern, work of breathing and blood gas exchange in 8 patients with acute respiratory failure. During ACV, the tidal volume was set at 10 ml/kg, and the inspiratory flow was set at 50 to 70 l/min. During PSV, the pressure support level selected was 27 +/- 5 cm H2O to make the breathing pattern regular. Tidal volume was significantly higher (908 +/- 179 ml vs. 633 +/- 96 ml) during PSV than during ACV at a lower peak airway pressure. Respiratory frequency was lower (15 +/- 4 breaths/min vs. 24 +/- 5 breaths/min) during PSV than during ACV, associated with a lower duty cycle, which improved synchrony between the patient and the ventilator. The oxygen cost of breathing, an estimate based on the inspiratory work added by a ventilator and the oxygen consumption, did not change significantly. PaO2 was significantly higher during PSV than during ACV. We conclude that PSV using high levels of pressure support can improve the breathing pattern and oxygenation and fully sustain the patient's ventilation while matching his inspiratory efforts.

Adult↗
PubMed1989

High fat, low carbohydrate, enteral feeding lowers PaCO2 and reduces the period of ventilation in artificially ventilated patients.

The objective of this study was to compare the effect of a high fat, low carbohydrate enteral feed with a standard isocaloric, isonitrogenous enteral feed on PaCO2 and ventilation time in patients with acute respiratory failure requiring artificial ventilation. 20 clinically stable patients requiring enteral feeding were randomized to either feed in a double-blind fashion. Initial ventilator standard settings were adjusted according to clinical state. Measurements including minute volume and arterial blood gases were made twice daily. Weaning was carried out according to set criteria. During the feeding period, PaCO2 just prior to weaning fell by 16% in the high fat group but increased by 4% in the standard feed group (p = 0.003). The high fat group spent a mean of 62 h less time on the ventilator (p = 0.006). A high fat, low carbohydrate enteral feed appears to be beneficial in patients undergoing artificial ventilation.

Adult↗
PubMed1996

Pressure-limited ventilation with permissive hypercapnia and minimum PEEP in saline-lavaged rabbits allows progressive improvement in oxygenation, but does not avoid ventilator-induced lung injury.

OBJECTIVE: To determine whether pressure-limited intermittent mandatory ventilation with permissive hypercapnia and positive end-expiratory pressure (PEEP) titrated to arterial oxygen tension (PaO2) prevents or reduces acute lung injury, compared to conventional ventilation, in saline-lavaged rabbits. DESIGN: Prospective randomised trial. SETTING: University animal laboratory. SUBJECTS: 18 New Zealand White rabbits. INTERVENTIONS: Following five sequential saline lung lavages, anaesthetised rabbits were randomly allocated in pairs to receive either of two ventilation protocols using intermittent mandatory ventilation. The study group had peak inspiratory pressure limited to 15 cm H2O and arterial partial pressure of carbon dioxide (PaCO2) was allowed to rise. The control group received 12 ml/kg tidal volume with rate adjusted for normocarbia. PEEP and fractional inspired oxygen (FIO2) were adjusted to maintain, PaO2 between 8 and 13.3 kPa (60 and 100 mm Hg) using a predetermined protocol. At 10 h or following death, lung lavage was repeated and lung histology evaluated. MEASUREMENTS AND MAIN RESULTS: The mean increase in lavage cell counts and protein concentration and hyaline membrane scores were not significantly different between the groups. Oxygenation progressively improved more in the study group (p = 0.01 vs control for PaO2/FIO2 ratio and alveolar-arterial oxygen tension gradient (AaDO2)). PEEP was similar and the mean airway pressure higher in the control group, suggesting that this probably resulted from less ventilator-induced injury in the study group. Four deaths occurred in the control group (three due to pneumothorax and one to hypoxaemia) and none in the study group (p = 0.08). CONCLUSIONS: This ventilatory protocol may have failed to prevent lung overdistension or it may have provided insufficient PEEP to prevent injury in this model; PEEP greater than the lower inflection point of the pressure-volume curve has been shown to prevent injury almost entirely.

Animals↗
PubMed1991

Patient triggered ventilation in chronically ventilator-dependent infants.

Patient triggered ventilation (PTV) has been assessed as a method of respiratory support in infants remaining ventilator-dependent beyond the 1st week of life. Sixteen preterm infants were studied who had a median gestational age of 26 weeks and postnatal age of 22 days. PTV was delivered using a ventilator incorporating an airway pressure trigger. PTV was only successfully maintained until extubation in 3 infants, failing to provide a satisfactory method of respiratory support in the remaining 13 infants after a median of 1 h (range 1-10). One of the 13 infants was persistently asynchronous at 1 h despite manipulation of inflation time. The other 12 infants, at failure of PTV, were making respiratory efforts which were inadequate to consistently trigger the ventilator. Infants in whom PTV was successful were older, more mature and of greater birth weight; the trigger delay at 1 h was significantly shorter in this group (P less than 0.05). A predictor of failure of PTV was asynchrony in the 1st h after commencing PTV (P less than 0.02). We conclude PTV incorporating an airway pressure trigger infrequently provides a useful method of respiratory support in infants who are chronically ventilator-dependent.

Humans↗