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PubMed1998

[Bellows or bag? Testing 10 ventilators and some medical history comments].

We compared a new bellows ventilator (Kendall Cardiovent) with two other bellows (Dräger Resutator 63, Tagg Breathsaver) and seven bag or ball ventilators (Aerodyne Hope, Ambu Mark 3, Ambu Silicon, Dräger Resutator 2000, Laerdal Resu, Mercury CPR, Weinmann Combibag). Tidal volumes were measured with two Laerdal Recording Resusci Annies, one lying on the floor, one in a bed. Twelve participants performed mask ventilation with all ten devices on both manikins for two minutes, trying to achieve tidal volumes of between 0.8 and 1.21 as recommended by the AHA. The last ten ventilations each on the graphic strips were analysed for volume. The participants scored handling of the devices on a 6-point scale (1 = very good, 6 = insufficient). The results of the Cardiovent were compared to those of the other devices by rank sum test (percentage of correct ventilations) and sign test (subjective handling). The Cardiovent provided exact ventilation with 95% of ventilations) on the floor and 78% of ventilations in bed in the recommended range. However, the percentage of correct ventilations with the Cardiovent was not significantly different to the other devices except for a lower percentage of correct ventilations with the Combibag in the in bed setting. Concerning subjective handling, the Cardiovent was significantly superior to several ball ventilators.

Equipment Design↗
PubMed1992

Management of a piglet model of the meconium aspiration syndrome with high-frequency or conventional ventilation.

OBJECTIVE: To assess the usefulness of three methods of high-frequency ventilation in the early management of a piglet model of the meconium aspiration syndrome. DESIGN: Randomized, block design. SETTING: Animal research facility. SUBJECTS: Fifty-six mixed-breed newborn piglets aged 1 to 4 days and weighing 1.8 to 2.7 kg. INTERVENTIONS: After instillation of a 2.2-mL/kg solution of 25% meconium, 56 piglets were randomized to receive treatment with (1) a conventional positive-pressure infant ventilator, (2) the Bunnell Life Pulse high-frequency jet ventilator, (3) the Bird model VDR high-frequency flow interruptor, or (4) the Infant Star high-frequency flow interruptor. We adjusted ventilator settings to maintain partial pressures of arterial oxygen (PaO2) of 80 to 120 cm H2O and partial pressures of arterial carbon dioxide (PaCO2) of 30 to 50 cm H2O during the 6 hours of ventilation. MEASUREMENTS AND MAIN RESULTS: We compared pulmonary histologic alterations and four physiologic parameters: (1) mean airway pressure, (2) PaCO2, (3) ratio of PaO2 to partial alveolar oxygen pressure (PAO2), and (4) oxygenation index ([(fraction of inspired oxygen)(mean airway pressure)(100)]/PaO2). The two measures of oxygenation were similar for all four devices except at 4 hours, when the PaO2/PAO2 ratio on positive-pressure ventilation was significantly higher than that on high-frequency jet ventilation (P = .008). The histologic changes on positive-pressure ventilation (atelectasis, inflammation, presence of meconium, and exudative debris) were significantly worse than those on high-frequency jet ventilation or flow interruption (P < .0001). CONCLUSIONS: The finding of less severe pathologic alterations with various types of high-frequency ventilators justifies further investigations into the management of the meconium aspiration syndrome with these devices.

Animals↗
PubMed2000

Neuromuscular paralysis for newborn infants receiving mechanical ventilation.

BACKGROUND: Ventilated newborn infants breathing in asynchrony with the ventilator are at risk for complications during mechanical ventilation, such as pneumothorax or intraventricular hemorrhage, and are exposed to more severe barotrauma, which consequently could impair their clinical outcome. Neuromuscular paralysis, which eliminates spontaneous breathing efforts of the infant, has potential advantages in this respect. However, a number of complications have been reported with muscle relaxation in infants, so that concerns exist regarding the safety of prolonged neuromuscular paralysis in newborn infants. OBJECTIVES: To determine whether routine neuromuscular paralysis of newborn infants receiving mechanical ventilation compared with no routine paralysis results in clinically important benefits or harms. SEARCH STRATEGY: MEDLINE (from 1966 to May 2000) and EMBASE (from 1988 to May 2000) were searched, as well as The Cochrane Controlled Trials Register (issue 2, 2000). References of review articles were hand searched. Language restriction was not imposed. SELECTION CRITERIA: All trials using random or quasi-random patient allocation, in which the routine use of neuromuscular blocking agents during mechanical ventilation was compared to no paralysis or selective paralysis in newborn infants. Methodological quality was assessed blindly and independently by the two authors. DATA COLLECTION AND ANALYSIS: Data were abstracted using standard methods of the Cochrane Collaboration and its Neonatal Review Group, with independent evaluation of trial quality, and abstraction and synthesis of data by both authors. Treatment effect was analysed using relative risk, risk difference and weighted mean difference. MAIN RESULTS: Ten possibly eligible trials were identified, of which five were included in the review. All the included trials studied preterm infants ventilated for respiratory distress syndrome, and used pancuronium as the neuromuscular blocking agent. In the analysis of the results of all trials, no difference was found in mortality, air leak or chronic lung disease, but there was a significant reduction in intraventricular hemorrhage and a trend towards less severe intraventricular hemorrhages. In the subgroup analysis of trials studying a selected population of ventilated infants with evidence of asynchronous respiratory efforts, a significant reduction in intraventricular hemorrhage (any grade and severe IVH) was found, and a trend towards less air leak. In the subgroup analysis of trials studying an unselected population of ventilated infants, no differences were found for any of the outcomes. REVIEWER'S CONCLUSIONS: For ventilated preterm infants with evidence of asynchronous respiratory efforts, neuromuscular paralysis with pancuronium seems to have a favourable effect on intraventricular hemorrhage and possibly on air leak. Uncertainty remains, however, regarding the long term pulmonary and neurologic effects, and regarding the safety of prolonged use of pancuronium in ventilated newborn infants. There is no evidence from randomized trials on the effects of neuromuscular blocking agents other than pancuronium. Therefore, the routine use of pancuronium or any other neuromuscular blocking agent in ventilated newborn infants cannot be recommended based on current evidence.

Cerebral Hemorrhage↗
PubMed2005

Neuromuscular paralysis for newborn infants receiving mechanical ventilation.

BACKGROUND: Ventilated newborn infants breathing in asynchrony with the ventilator are at risk for complications during mechanical ventilation, such as pneumothorax or intraventricular hemorrhage, and are exposed to more severe barotrauma, which consequently could impair their clinical outcome. Neuromuscular paralysis, which eliminates spontaneous breathing efforts of the infant, has potential advantages in this respect. However, a number of complications have been reported with muscle relaxation in infants, so that concerns exist regarding the safety of prolonged neuromuscular paralysis in newborn infants. OBJECTIVES: To determine whether routine neuromuscular paralysis of newborn infants receiving mechanical ventilation compared with no routine paralysis results in clinically important benefits or harms. SEARCH STRATEGY: The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2004), MEDLINE (from 1966 to April 2004) and EMBASE (from 1988 to April 2004) were searched. References of review articles were hand searched. Language restriction was not imposed. SELECTION CRITERIA: All trials using random or quasi-random patient allocation, in which the routine use of neuromuscular blocking agents during mechanical ventilation was compared to no paralysis or selective paralysis in newborn infants. Methodological quality was assessed blindly and independently by the two authors. DATA COLLECTION AND ANALYSIS: Data were abstracted using standard methods of the Cochrane Collaboration and its Neonatal Review Group, with independent evaluation of trial quality, and abstraction and synthesis of data by both authors. Treatment effect was analysed using relative risk, risk difference and weighted mean difference. MAIN RESULTS: Ten possibly eligible trials were identified, of which six were included in the review. All the included trials studied preterm infants ventilated for respiratory distress syndrome, and used pancuronium as the neuromuscular blocking agent. In the analysis of the results of all trials, no significant difference was found in mortality, air leak or chronic lung disease, but there was a significant reduction in intraventricular hemorrhage and a trend towards less severe intraventricular hemorrhages. In the subgroup analysis of trials studying a selected population of ventilated infants with evidence of asynchronous respiratory efforts, a significant reduction in intraventricular hemorrhage (any grade and severe IVH) was found, and a trend towards less air leak. In the subgroup analysis of trials studying an unselected population of ventilated infants, no significant differences were found for any of the outcomes. AUTHORS' CONCLUSIONS: For ventilated preterm infants with evidence of asynchronous respiratory efforts, neuromuscular paralysis with pancuronium seems to have a favourable effect on intraventricular hemorrhage and possibly on air leak. Uncertainty remains, however, regarding the long term pulmonary and neurologic effects, and regarding the safety of prolonged use of pancuronium in ventilated newborn infants. There is no evidence from randomized trials on the effects of neuromuscular blocking agents other than pancuronium. The routine use of pancuronium or any other neuromuscular blocking agent in ventilated newborn infants cannot be recommended based on current evidence.

Cerebral Hemorrhage↗
PubMed2004

Ventilation prevents pulmonary endothelial dysfunction and improves oxygenation after cardiopulmonary bypass without aortic cross-clamping.

OBJECTIVE: Endothelial dysfunction of the pulmonary arterial tree occurring after cardiopulmonary bypass (CPB) contributes to pulmonary hypertension and respiratory failure in the postoperative period. The goal of the present study was to characterize the alterations of endothelial cell signal transduction pathways in pulmonary arteries following CPB, the effect of ventilation and nitric oxide (NO) inhalation on endothelium-dependent relaxations and the alterations in hemodynamics and oxygenation. METHODS: Six groups of Landrace swine were compared: control, sham without CPB, CPB 150min+no reperfusion, CPB 150min+reperfusion 60 min, CPB 150min+ventilation (tidal volume 12 ml/kg)+reperfusion 60 min, and CPB 150min+NO inhalation (with ventilation, NO 40 ppm)+60 min of reperfusion. No cross-clamping was applied, the heart was left beating, empty. Pulmonary artery reactivity was evaluated in organ chambers to assess the endothelium-dependent relaxations. RESULTS: CPB alone did not alter endothelial function. CPB and pulmonary reperfusion induced a statistically significant decrease in endothelium-dependent relaxations to acetylcholine. Mechanical ventilation during CPB prevented the reduction of relaxations to acetylcholine. Ventilation and NO inhalation during CPB did not differ from ventilation alone in terms of endothelium-dependent relaxations. There were no differences between groups for relaxations to bradykinin. There was a significant increase in arterial oxygen tension in the ventilated group compared to the non-ventilated group. CONCLUSION: Pulmonary reperfusion after CPB causes a selective dysfunction of Gi-protein-mediated relaxations. Mechanical ventilation prevents the pulmonary endothelial dysfunction due to reperfusion after CPB. Ventilation also improves oxygenation after CPB. Mechanical ventilation could be used as a preventive approach for patients undergoing cardiac surgery with extracorporeal circulation.

Administration, Inhalation↗
PubMed2002

Optimizing ventilation in conjunction with phased chest and abdominal compression-decompression (Lifestick) resuscitation.

The best method for employment of phased chest and abdominal compression-decompression (Lifestick) cardiopulmonary resuscitation (CPR) has yet to be determined. Of particular concern with using this technique is the combining of ventilation with the phased compressions and decompressions. Twenty domestic swine (50+/-1 kg) were equally divided into four groups. Following 10 min of untreated VF, CPR was begun. Group 1 received Lifestick (LS) CPR with only passive ventilation ('passive'); Group 2 received LS-CPR with synchronized positive pressure ventilations (ppv) at a chest compression ratio of 15:2 (15:2 S); Group 3 had LS-CPR with synchronized ppv at 5:1 (5:1 S); and Group 4 received LS-CPR with asynchronous ppv at 5:1 (5:1 A). Endpoints included hemodynamics, blood gases, minute ventilation, and 24 h outcome. Asynchronous ventilation (5:1 A) had significantly worse hemodynamics including aortic and right atrial systolic, aortic diastolic, and coronary perfusion pressures than the other groups (P<0.05). Passive ventilation had the poorest arterial and mixed venous blood gases (P<0.05), but did not differ from 15:2 S in minute ventilation produced (8 vs 10 l/min). No differences in outcome were seen. The ventilation technique combined with LS-CPR can make a significant difference in hemodynamics as well as ventilation. Optimizing other forms of basic and advanced cardiac life support through different ventilation methods deserves new consideration, including a re-examination of the current single rescuer recommendation of a 15:2 ratio. Optimal ventilation strategy when using the LS device at 60 compressions per min appears to be 5:1 S. Such data is important for conducting clinical trials with this new CPR adjunct.

Abdomen↗
PubMed2003

Artificial ventilation for basic life support leads to hyperventilation in first aid providers.

The 'Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care - International Consensus on Science' recommend an artificial ventilation volume of 10 ml/kg bodyweight (equivalent to a tidal volume of 700-1000 ml) without the use of supplemental oxygen in adults with respiratory arrest. For first aid providers using the mouth-to-mouth or mouth-to-nose-ventilation technique, respectively, a ventilation volume of approximately 9.6 l/min results. Additionally, a deep breath is recommended before each ventilation to increase the end-expiratory oxygen concentration of the air exhaled by the first aid provider. To investigate the effects of these recommendations in healthy volunteers, test persons were asked to ventilate an artificial lung model for a period of up to 10 min. The tidal volume was set at 800 ml at a breathing rate of 12/min. End-tidal carbon dioxide, oxygen saturation (measured by pulse oximetry), and heart rate were measured continuously. Capillary blood gas samples were collected and non-invasive blood pressure readings were recorded prior to the start of ventilation and immediately after the end of the measuring period. The data reveal a statistically significant and clinically relevant decrease in end-tidal carbon dioxide pressure (P<0.001, median decrease 14 mmHg), and the occurrence of hyperventilation-associated symptoms such as paraesthesia, dizziness, and carpopedal spasms in more than 75% of the participants. Clinically and statistically significant hyperventilation results in first aid providers performing artificial ventilation according to the guidelines. This artificial ventilation is associated with a significant decrease in capillary and end-tidal carbon dioxide pressure as well as with multiple symptoms of an acute hyperventilation syndrome. Ventilation performed according to these guidelines may cause injury to the health of the first aid provider. Rescuers ventilating the victim should be replaced at regular intervals and the recommendation to take a deep breath before each ventilation should not be upheld in order to minimise the risk of hyperventilation.

Adult↗
PubMed2004

[Home mechanical ventilation: indications and pathophysiological limitations].

INTRODUCTION: Domiciliary assisted ventilation (DAV) may be undertaken invasively or non-invasively. Non-invasive DAV is used for patients suffering from alveolar hypoventilation due to restrictive pathology. Invasive DAV is reserved for "indications of necessity" that is when non-invasive ventilation is contraindicated due to the absence of adequate cough and for alveolar hypoventilation leading to hypercapnoea during spontaneous ventilation. STATE OF THE ART: The main pathophysiological limitation to non-invasive ventilation is the interference of the glottis. In this mode the glottis imposes a variable resistance to the ventilation delivered. Its behaviour is more predictable during Volume controlled than during pressure controlled ventilation. The control parameters of a Volume controlled ventilator are very different from those used in invasive ventilation during which the respiratory system may be regarded as a single compartment (provided a cuffed tube bypasses the upper airway). In non-invasive DAV: mode VCM, tidal volume 13 mls kg(-1), rate 20 cycles min(-1), insp/exp ratio 1/1.2. In invasive DAV: mode VCM, tidal volume 8-10 mls kg(-1), rate 12 cycles min(-1), insp/exp ratio depending on the pathology 1/2. PERSPECTIVES: As non-invasive DAV is essentially delivered during sleep the parameters for each patient can be optimised during polysomnography because waking, leading to a partial glottic occlusion, interferes with the ventilation delivered. CONCLUSIONS: Recent understanding of the way the glottis interferes with mechanical ventilation when delivered non-invasively should lead to a revision of earlier practices based on invasive ventilation.

Contraindications↗
PubMed2001

Pressure controlled versus volume controlled ventilation with laryngeal mask airway.

STUDY OBJECTIVE: To quantify the impact on peak airway pressure of pressure-controlled and volume-controlled ventilation during Laryngeal Mask Airway (LMA) use. DESIGN: Prospective, crossover clinical study. SETTING: University-affiliated hospital. PATIENTS: 32 ASA physical status I and II patients undergoing general anesthesia with the LMA. INTERVENTIONS: Patients were ventilated for three minutes both with pressure-controlled and volume-controlled ventilation, provided that tidal volume (V(T) ) and inspiratory time (It) were constant. MEASUREMENTS AND MAIN RESULTS: The monitored parameters were electrocardiography, arterial blood pressure, pulse oximetry, capnography, neuromuscular transmission, airway pressure and flow, and concentration of ventilated vapors and gases. The actually delivered V(T) was similar with both types of ventilation (volume-controlled = 0.67 +/- 0.13 lt, pressure-controlled = 0.67 +/- 0.14 lt; p = 0.688). Peak airway pressure was lower during pressure-controlled ventilation (14.6 +/- 3.5 cmH(2)O) than during volume-controlled ventilation (16 +/- 4 cmH(2)O) (p < 0.001). Furthermore, we noted that the higher the airway pressure with volume-controlled ventilation, the greater was the reduction in airway pressure during pressure-controlled ventilation. CONCLUSIONS: Pressure-controlled rather than volume-controlled ventilation can improve the effectiveness of mechanical ventilation in patients with high airway pressure.

Adult↗
PubMed2000

The effect of intratracheal pulmonary ventilation on the decrease of dead space in rabbits with acute respiratory failure.

OBJECTIVE: A technique that improves the efficiency of alveolar ventilation should decrease the pressure required and reduce the potential for lung injury during mechanical ventilation. High partial pressure of carbon dioxide (PaCO2) can be tolerated if associated with a lower airway pressure as in permissive hypercapnia (PH). Intratracheal pulmonary ventilation (ITPV) was developed to allow a decrease in physiological dead space during mechanical ventilation. We compared the effect of hybrid ventilation (HV) as a modification of ITPV with PH on the decrease of tidal volume and airway pressures in rabbits with acute respiratory failure. METHODOLOGY: Tracheostomy was performed in seven rabbits ventilated under volume-controlled mode in the supine position. Arterial blood gas analysis, airway pressures, and dead space ventilation were measured at respiratory rates of 20/min as control values. Oleic acid (OA) of 0.06 mL/kg was injected to induce acute respiratory failure. Tidal volume (V(T)) was elevated to maintain PaCO2 in the normal range. These same parameters were measured as OA values. Then V(T) was reduced to the control level to allow PH. Hybrid ventilation was initiated by inserting a reverse thrust catheter (RTC) into the endotracheal tube. Hybrid ventilation consists of a pressure-controlled mode of mechanical ventilation and ITPV while flushing fresh gas continuously via the RTC. Respiratory parameters were compared under control, OA, PH and HV conditions. RESULTS: Oleic acid injection decreased partial pressure of oxygen (PaCO2) from 401+/-35 mmHg to 129+/-39 mmHg, increased V(T) from 42+/-5 mL to 52+/-10 mL, and increased dead space (V(D))/V(T) ratio from 0.65+/-0.07 to 0.71+/-0.07. During PH, the increase in PaCO2 was accompanied by an increase in V(D)/V(T) ratio from 0.71+/-0.07 to 0.79+/-0.03 and by a decrease of peak inspiratory pressure (PIP) from 19.4+/-4.0 cmH2O to 16.8+/-3.1 cmH2O. PaCO2 was lowered from 50+/-5 mmHg in PH to 39+/-5 mmHg in HV with a lower V(T). V(D)/V(T) ratio in HV which was as low as that in control. CONCLUSIONS: Hybrid ventilation is an effective and easy-to-use ventilatory modality to reduce PaCO2 and airway pressures by the reduction in V(D)/V(T) ratio in acute respiratory failure model.

Acute Disease↗
PubMed2002

Non-invasive positive pressure ventilation in patients with acute respiratory failure.

Non-invasive positive pressure ventilation is an emerging modality in contemporary critical care practice. Perhaps the most widely utilized and familiar form of non-invasive positive pressure ventilation is mask continuous positive airway pressure. Other common modes include mask Bi-level positive airway pressure and mask pressure support ventilation. All feature the delivery of positive airway pressure via a mask (full-face, naso-oral or nasal), and a patient-controlled respiratory cycle. The physiological benefits of non-invasive positive pressure ventilation suggested by a number of studies include improved oxygenation, decreased work of breathing, improved ventilation and perfusion matching, decreased fatigue, and increased minute ventilation. The utilization of non-invasive positive pressure ventilation has now been reported for a variety of clinical indications. In most, randomized trials are lacking, and the benefits and preferred mode of non-invasive positive pressure ventilation are still to be elucidated. In general, in patients that are candidates for endotracheal intubation, non-invasive positive pressure ventilation should be used as a way to possibly avoid endotracheal intubation rather than as an alternative to endotracheal intubation. Whilst the benefit of non-invasive positive pressure ventilation appears to be established in patients with chronic obstructive airways disease with hypercapnic acute respiratory failure, one of the major unresolved issues is whether one modality is significantly better than the others. Unfortunately, the question of whether Bi-level positive airway pressure is better than continuous positive airway pressure in this clinical scenario has not been satisfactorily addressed in any large randomized and controlled clinical trial. Further, there is no 'gold standard' for predicting success with non-invasive positive pressure ventilation, although several studies have looked at this aspect.

Acute Disease↗
PubMed2000

[Ventilation according to the "open lung" concept of multiple trauma patients].

OBJECTIVE: The ventilation mode clearly influences the course of patients with multiple trauma on the ICU. Ventilation according the "open lung" approach rapidly opens up atelectatic lung regions. Generation of an adequate intrinsic PEEP enables to keep the lung open. We studied the consequences of the "open lung" approach on the lung function and monitored its side effects on patients with multiple trauma. METHODS: 18 consecutive patients with multiple trauma and additional thoracic trauma were routinely ventilated according the "open lung" approach between May and November 1999. We were mainly interested in data of lung mechanics, oxygenation and ventilation. Side effects on other organ systems and consequence for the infection rate were monitored. RESULTS: Ventilation according the "open lung" approach enables early sufficient oxygenation and ventilation of patients with severe multiple trauma and accompanying thoracic trauma. The ventilation mode helps to prevent baro-, volu- and atelectrauma and thus fulfils the requirements for a present-day ventilation mode. An immediate complete healing of the lung damages was not found. Nevertheless, as a trend the length of ventilation support seems short. Even extensive osteosynthesis at multiple fractures was possible without delay. Side effects of the high opening pressure on the lung or other organs as well as sequels of the high intrinsic PEEP on liver, kidney or intestine were not found. The infection rate was low, therapeutic doses of antibiotics were necessary only in less than half of the ICU-stay. CONCLUSION: Ventilation according the "open lung" approach is a very effective and safe way to ventilate patients after severe multiple trauma with accompanying thoracic trauma.

Adolescent↗
PubMed2001

Optimizing patient-ventilator synchrony.

Mechanical ventilation assumes the work of breathing, improves gas exchange, and unloads the respiratory muscles, all of which require good synchronization between the patient and the ventilator. Causes for patient-ventilator dyssynchrony include both patient factors (abnormalities of respiratory drive and abnormal respiratory mechanics) and ventilator factors (triggering, flow delivery, breath termination criteria, the level and mode of ventilator support, and imposed work of breathing). Although patient-ventilator dyssynchrony can often be detected on physical exam, careful analysis of ventilator waveforms (pressure-time, flow-time) allows for more precise definition of the underlying cause. Patient-ventilator interaction can be improved by reversing patient factors that alter respiratory drive or elevate patient ventilatory requirements and by correcting factors that contribute to dynamic hyperinflation. Proper setting of the ventilator using sensitive triggering mechanisms, satisfactory flow rates, adequate delivered minute ventilation, matching machine T(I) to neural T(I), and applying modes that overcome the imposed work of breathing, further optimize patient-ventilator synchrony.

Journal Article↗
PubMed1995

Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: In patients with acute exacerbations of chronic obstructive pulmonary disease, noninvasive ventilation may be used in an attempt to avoid endotracheal intubation and complications associated with mechanical ventilation. METHODS: We conducted a prospective, randomized study comparing noninvasive pressure-support ventilation delivered through a face mask with standard treatment in patients admitted to five intensive care units over a 15-month period. RESULTS: A total of 85 patients were recruited from a larger group of 275 patients with chronic obstructive pulmonary disease admitted to the intensive care units in the same period. A total of 42 were randomly assigned to standard therapy and 43 to noninvasive ventilation. The two groups had similar clinical characteristics on admission to the hospital. The use of noninvasive ventilation significantly reduced the need for endotracheal intubation (which was dictated by objective criteria): 11 of 43 patients (26 percent) in the noninvasive-ventilation group were intubated, as compared with 31 of 42 (74 percent) in the standard-treatment group (P < 0.001). In addition, the frequency of complications was significantly lower in the noninvasive-ventilation group (16 percent vs. 48 percent, P = 0.001), and the mean (+/- SD) hospital stay was significantly shorter for patients receiving noninvasive ventilation (23 +/- 17 days vs. 35 +/- 33 days, P = 0.005). The in-hospital mortality rate was also significantly reduced with noninvasive ventilation (4 of 43 patients, or 9 percent, in the noninvasive-ventilation group died in the hospital, as compared with 12 of 42, or 29 percent, in the standard-treatment group; P = 0.02). CONCLUSIONS: In selected patients with acute exacerbations of chronic obstructive pulmonary disease, noninvasive ventilation can reduce the need for endotracheal intubation, the length of the hospital stay, and the in-hospital mortality rate.

Acute Disease↗
PubMed1991

Cardiopulmonary effects of constant-flow ventilation in experimental myocardial ischaemia.

The cardiopulmonary effects of constant-flow ventilation were investigated in dogs with normal heart function (control-phase, n = 14) and after development of acute myocardial ischaemia (ischaemia phase, n = 14). Heated, humidified and oxygen-enriched air was continuously delivered with an inspiratory flow rate of 1.21.kg-1.min-1 via two catheters positioned within each mainstem bronchus. Continuous positive pressure ventilation with a positive end-expiratory pressure of 0.5 kPa (5 cmH2O) was used as a reference. During control, neither continuous positive pressure ventilation nor constant-flow ventilation showed impairment of cardiopulmonary performance. Oxygenation and CO2 removal were more efficiently achieved by continuous positive pressure ventilation (P less than or equal to 0.05). Acute myocardial ischaemia was induced by occlusion of the left anterior descending (LAD) coronary artery; measurements during the ischaemia phase were performed 60 min following LAD occlusion. Myocardial ischaemia resulted in moderate changes of cardiac output, left ventricular end-diastolic pressure and dP/dtmax. Both modes of ventilation were well tolerated in the ischaemia phase, and cardiovascular performance revealed no significant differences between continuous positive pressure ventilation and constant-flow ventilation. Haemodynamic parameters could be more precisely assessed during constant-flow ventilation. Oxygenation deteriorated, but hypoxaemia did not occur in any animal and CO2 elimination remained unchanged. It is concluded that 'non-conventional' ventilation by continuous intrabronchial gas flow maintains adequate gas exchange with no adverse effects on haemodynamics in dogs with acute myocardial ischaemia. Constant-flow ventilation may be advantageous in the experimental setting to study cardiac function without cyclic heart-lung interaction due to airway pressure alterations.

Animals↗
PubMed1999

Fiberoptic-guided airway exchange of the esophageal-tracheal Combitube in spontaneously breathing versus mechanically ventilated patients.

UNLABELLED: The aim of this study was to compare fiberoptic-guided airway exchange of the esophageal-tracheal Combitube (ETC, Kendall-Sheridan Catheter Corp., Argyle, NY) with an endotracheal tube in spontaneously breathing versus mechanically ventilated patients. Forty patients with Mallampati score III and IV scheduled for elective surgery were randomly allocated into two groups (n = 20 each): nonparalyzed, spontaneously breathing or paralyzed, mechanically ventilated patients. After anesthetic induction and insertion of the ETC, a fiberoptic bronchoscope threaded into an armored endotracheal tube was passed transnasally into the larynx. Endotracheal intubation was successful in 18 spontaneously breathing patients and in 15 patients during controlled ventilation. Successful airway exchange was completed in significantly less time (P < 0.05) in spontaneously breathing patients (9+/-3 min; mean +/- SD) than in mechanically ventilated patients (13+/-4 min). Both methods allowed for continuous airway control and maintenance of ventilation and oxygenation. The described method is a means of replacing the ETC with an endotracheal tube without interruption of airway control or ventilation. Replacing the ETC with an endotracheal tube using this method is more readily accomplished during spontaneous ventilation than during controlled ventilation. IMPLICATIONS: We describe the replacement of the Combitube by an endotracheal tube by the aid of fiberoptic bronchoscopy and without interruption of airway control or ventilation. The performance of this technique was facilitated by spontaneous ventilation compared with mechanical ventilation.

Adult↗
PubMed1993

Perfluorocarbon-associated gas exchange (partial liquid ventilation) in respiratory distress syndrome: a prospective, randomized, controlled study.

OBJECTIVE: To determine the efficacy of perfluorocarbon-associated gas exchange (partial liquid ventilation) in respiratory distress syndrome. DESIGN: Prospective, randomized, controlled study. SETTING: State University of New York at Buffalo, School of Medicine and Biomedical Sciences. SUBJECTS: Eleven premature lambs with respiratory distress syndrome, delivered by cesarean section. INTERVENTIONS: Five lambs were supported by conventional mechanical ventilation alone. Six lambs were switched to perfluorocarbon-associated gas exchange after 60 to 90 mins of conventional mechanical ventilation. Perfluorocarbon-associated gas exchange was accomplished by instilling a volume of liquid perfluorocarbon equivalent to normal functional residual capacity (30 mL/kg) into the trachea, performing 3 to 4 mins of tidal liquid ventilation, and, at end-expiration, with liquid functional residual capacity of 30 mL/kg remaining in the lung, reconnecting the animal to the volume ventilator for gas tidal volumes. MEASUREMENTS AND MAIN RESULTS: Serial arterial blood gases and lung mechanics were measured. While receiving conventional ventilation, all animals developed progressive hypoxemia, hypercarbia, and acidosis. However, in the perfluorocarbon-associated gas exchange group, within 5 mins of the initiation of perfluorocarbon-associated gas exchange, mean PaO2 increased four-fold, from 59 +/- 6 torr (7.9 +/- 0.8 kPa) during conventional ventilation to 250 +/- 28 torr (33.3 +/- 3.7 kPa; p < .05) during perfluorocarbon-associated gas exchange, and this increase was sustained at 60 mins of perfluorocarbon-associated gas exchange (268 +/- 38 torr; 35.7 +/- 5.1 kPa; p < .05). Mean PaCO2 decreased progressively from 62 +/- 4 torr (8.3 +/- 0.5 kPa) during conventional ventilation to 38 +/- 3.3 torr (5.1 +/- 0.4 kPa) at 60 mins of perfluorocarbon-associated gas exchange (p < .05). Mean pH concomitantly increased. Dynamic compliance increased three-fold within 15 mins of instituting perfluorocarbon-associated gas exchange, from 0.31 +/- 0.02 mL/cm H2O during conventional ventilation to 0.90 +/- 0.11 mL/cm H2O during perfluorocarbon-associated gas exchange, and this increase was sustained at 60 mins of perfluorocarbon-associated gas exchange (p < .05). Mean peak expiratory flow and mean expiratory resistance were essentially unchanged during perfluorocarbon-associated gas exchange as compared with conventional ventilation in the same group. CONCLUSIONS: We conclude that perfluorocarbon-associated gas exchange, which employs liquid functional residual capacity and gas tidal volumes delivered by a conventional ventilator, can facilitate oxygenation and CO2 removal, and dramatically improve lung mechanics in the premature lamb with respiratory distress syndrome.

Airway Resistance↗
PubMed1994

Nasal mechanical ventilation for hypercapnic respiratory failure in chronic obstructive pulmonary disease: determinants of success and failure.

OBJECTIVES: To evaluate the efficacy of nasal mechanical ventilation in patients with chronic obstructive pulmonary disease and hypercapnic respiratory failure and to identify predictors of success or failure of nasal mechanical ventilation. DESIGN: Prospective case series. SETTING: Medical intensive care unit in Veterans Administration Medical Center. PATIENTS: Twelve chronic obstructive pulmonary disease patients treated during 14 episodes of hypercapnic respiratory failure. INTERVENTIONS: Nasal mechanical ventilation in addition to conventional therapy to treat hypercapnic respiratory failure. Patients underwent nasal mechanical ventilation for at least 30 mins, or longer if the therapy was tolerated. Responses to therapy and arterial blood gases were monitored. MEASUREMENTS AND MAIN RESULTS: Half of the episodes were successfully treated with nasal mechanical ventilation. There were no differences in age, prior pulmonary function, baseline arterial blood gases, admission arterial blood gases, or respiratory rate between those patients successfully treated and those patients who failed nasal mechanical ventilation. Unsuccessfully treated patients appeared to have a greater severity of illness than successfully treated patients, as indicated by a higher Acute Physiology and Chronic Health Evaluation II score (mean 21 +/- 4 [SD] vs. 15 +/- 4; p = .02). Unsuccessfully treated patients were edentulous, had pneumonia or excess secretions, and had pursed-lip breathing, factors that prevented adequate mouth seal and contributed to greater mouth leaks than in successfully treated patients (the mean volume of the mouth leak was 314 +/- 107 vs. 100 +/- 70 mL; p < .01). Successfully treated patients were able to adapt more rapidly to the nasal mask and ventilator, with greater and more rapid reduction in PaCO2, correction of pH, and reduction in respiratory rate. CONCLUSIONS: Patients who failed nasal mechanical ventilation appeared to have a greater severity of illness; they were unable to minimize the amount of mouth leak (because of lack of teeth, secretions, or breathing pattern) and were unable to coordinate with the ventilator. These features may allow identification of poor candidates for nasal mechanical ventilation, avoiding unnecessary delays in endotracheal intubation and mechanical ventilation.

Acute Disease↗