Fibreoptic intubation in patients after radiotherapy for carcinoma of the head and neck: difficulty and predictability.
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Adolescent↗
Biomedical subjects
H Mang
Publications and source records attributed to H Mang.
Inhalation of nitric oxide in acute lung injury: results of a European multicentre study. The European Study Group of Inhaled Nitric Oxide.
OBJECTIVE: To determine whether inhalation of nitric oxide (INO) can increase the frequency of reversal of acute lung injury (ALI) in nitric oxide (NO) responders. DESIGN: Prospective, open, randomised, multicentre, parallel group phase III trial. SETTING: General ICUs in 43 university and regional hospitals in Europe. PATIENTS: Two hundred and sixty-eight adult patients with early ALI. INTERVENTIONS: NO responders were patients whose PaO(2) increased by more than 20 % when receiving 0, 2, 10 and 40 ppm of INO for 10 min within 96 h of study entry. Responders were randomly allocated to conventional treatment with or without INO. INO, 1-40 ppm, was given at the lowest effective dose for up to 30 days or until an end point was reached. The primary end point was reversal of ALI. Clinical outcome parameters and safety were assessed in all patients. RESULTS: Two hundred and sixty-eight patients were recruited, of which 180 were randomised NO responders. Frequency of reversal of ALI was no different in INO patients (61 %) and controls (54 %; p > 0.2). Development of severe respiratory failure was lower in the INO (2.2 % ) than controls (10.3 %; p < 0.05). The mortality at 30 days was 44 % for INO patients, 40 % for control patients (p > 0.2 vs INO) and 45 % in non-responders. CONCLUSIONS: Improvement of oxygenation by INO did not increase the frequency of reversal of ALI. Use of inhaled NO in early ALI did not alter mortality although it did reduce the frequency of severe respiratory failure in patients developing severe hypoxaemia.
Administration, Inhalation↗
Expiratory phase tracheal gas insufflation and pressure control in sheep with permissive hypercapnia.
Tracheal gas insufflation (TGI) has been shown to be a useful adjunct to mechanical ventilation, decreasing PaCO2 during permissive hypercapnia. While TGI can be used either with pressure (PCV) or volume-controlled ventilation and continuously or only during the expiratory phase (Ex-TGI), there are no controlled studies evaluating the effects of Ex-TGI with PCV in acute lung injury when the direction of the insufflated flow or the inspiratory:expiratory (I:E) ratio are varied. We evaluated the effect that Ex-TGI with PCV would have on CO2 removal during both direct and reverse insufflated flow direction with varied I:E ratios when peak airway pressure, total positive end-expiratory pressure (PEEP), and tidal volume (VT) were kept constant. In addition we examined the effect that insufflation flow directed toward the mouth (reverse flow) would have on the generation of PEEP compared with flow directed toward the carina (direct flow). After saline lavage, nine sheep were ventilated with PCV to a baseline PaCO2 of 80 mm Hg. Ex-TGI (10 L/min) was then randomly applied in the reverse and direct direction with I:E set at 1:2 or 2:1. During 1:2 I:E PaCO2 decreased from 78 +/- 4 mm Hg to 60 +/- 7 mm Hg (23.5 +/- 8.9%) with direct flow and to 64 +/- 5 mm Hg (18.5 +/- 5.5%) with reverse flow (p < 0.05), whereas during 2:1 I:E PaCO2 decreased from 80 +/- 4 mm Hg to 69 +/- 8 mm Hg (13.7 +/- 9.2%) with direct flow and to 66 +/- 4 mm Hg (17.2 +/- 4.4%) with reverse flow (p < 0.05). Greater PEEP was developed with direct flow (2.8 cm H2O I:E 1:2 and 4.0 cm H2O I:E 2:1) than with reverse flow (-0.9 cm H2O I:E 1:2 and -0.4 cm H2O I:E 2:1), p < 0.05. There was no difference in the PaCO2 change between I:E with reverse flow, but the PaCO2 decrease was greater (p < 0.05) during 1:2 versus 2:1 I:E with direct flow. CO2 removal during PCV and Ex-TGI is more consistent with reverse flow than with direct flow and PEEP level is less affected by TGI with reverse flow than with direct flow.
Animals↗
Pressure-release tracheal gas insufflation reduces airway pressures in lung-injured sheep maintaining eucapnia.
Although tracheal gas insufflation (TGI) has proved to be a useful adjunct to mechanical ventilation, end-inspiratory as well as end-expiratory pressures may increase. We investigated the ability of continuous-flow TGI to maintain eucapnia while reducing airway pressure (Paw) and tidal volume (VT). Seven sheep (36 +/- 2 kg) were ventilated using the Dräger Evita 4 in the pressure control plus mode where flow is released via the expiratory valve to maintain constant inspiratory pressure. To avoid TGI-generated positive end-expiratory pressure (PEEP), a prototype reverse flow TGI tube was used. Two TGI flows (5 and 10 L/min) were investigated pre- and postsaline lavage-induced lung injury. Inspiratory pressures and VT were significantly reduced as TGI flow increased. At 10 L/min TGI flow the carinal pressures (Pcar) and VT were reduced pre- and postinjury by 15% and 20%, and by 28% and 34%, respectively. Tidal volume to dead space ratio (VD/VT) decreased preinjury from 0.49 +/- 0.1 to 0.18 +/- 0.2 and postinjury from 0.62 +/- 0.1 to 0.33 +/- 0.1 at a TGI flow of 10 L/min. The combination of the reverse flow TGI tube and a ventilator with an inspiratory pressure relief mechanism kept set end-inspiratory and end-expiratory pressures constant. This TGI system effectively reduced set Paw and VT while maintaining eucapnia.
Airway Resistance↗
[Contra: noninvasive ventilation in acute respiratory insufficiency].
Mechanical ventilation via a tracheal tube is an invasive measure whose complications may prevent recovery from respiratory failure. Today, noninvasive positive pressure ventilation via mouthpiece or mask is an economically and medically successful alternative for the treatment of chronic respiratory failure and acute exacerbation of COPD, respectively. Within certain limits, noninvasive ventilation may take over inspiratory work of breathing as well as elevate mean airway pressure and inspiratory oxygen concentration. This does not at all question the absolute indications to maintain a patent airway by tracheal intubation. Clinical applications of noninvasive ventilation within these limits are acute exacerbation of COPD, congestive heart failure with pulmonary edema or atelectasis. Respiratory muscle fatigue, cardiogenic and septic shock, severe pneumonia and ARDS are still absolute indications for invasive ventilation. Table 1 specifies 12 disadvantages and endpoints of noninvasive mechanical ventilation.
Contraindications↗
[Clinical concepts for differentiated ventilation].
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Humans↗
[Ventilator weaning after long-term ventilation--the concept of a regional ventilator weaning center].
Long-term mechanical ventilation implies a significant number of weaning failures. The basis of this unweanability is chronic fatigue of the inspiratory muscles which is due to depletion of energy store (e.g. glycogen). Considering this pathophysiological principle, the decisive therapeutic option during weaning from long-term mechanical ventilation consists of resting the respiratory muscles. The commonly used assisted ventilation modes only partially relieve the respiratory muscles because the work of breathing is done both during the trigger phase and during the inspiratory cycle. The essential characteristic of our weaning concept includes the repeated determination of the spontaneous breathing frequency in awake patients, which is followed by controlled intermittent positive pressure ventilation with a slightly higher respiratory rate. Ideally, this results in total suppression of the activity of the breathing centre, and in subsequent relief and recovery of the respiratory muscles by replenishing the energy stores. The close succession of relief and training periods avoids inactivity-induced atrophy of the respiratory muscles and permits regeneration. Additionally, our weaning concept avoids increases in inspiratory work during the phases of spontaneous breathing. This means that high-resistance small-caliber endotracheal tubes have to be replaced by large tubes. Moreover, transtracheal oxygen insufflation during spontaneous breathing decreases anatomic dead space. This reduces minute ventilation and, therefore, the work of breathing. In patients still exhibiting chronic fatigue of the respiratory muscle pump after successful weaning, intermittent home ventilation is initiated via a breathing mask. Apart from the concept described above, successful weaning from the respirator after long-term ventilation is based upon dedicated patient care and depends on the architectural characteristics of the intensive care unit.
Breathing Exercises↗
Cardiorespiratory effects of volume- and pressure-controlled ventilation at various I/E ratios in an acute lung injury model.
Numerous approaches to the provision of mechanical ventilation during acute lung injury are currently available. Of these, pressure control inverse ratio ventilation has been considered superior to volume control ventilation with PEEP with respect to improving gas exchange and minimizing cardiovascular compromise. However, no study systematically compares volume-controlled (VC) and pressure-controlled (PC) ventilation while maintaining mean airway pressure (MAP) constant at varying I/E ratios. We studied the effect of VC and PC with PEEP at normal (1:2) and inverse I/E ratios (2:1 and 4:1) on gas exchange, lung mechanics, and hemodynamics in a sheep lung injury model. Severe lung injury was induced in 12 sheep with bilateral lung lavages using normal saline; prelavage PO2 230 +/- 50 mm Hg, PEEP 5 cm H2O and postlavage, pretreatment PO2 70 +/- 20 mm Hg, PEEP 10 cm H2O, both at FIO2 0.50. MAP was kept constant throughout the study at 25 +/- 2 cm H2O while ventilating all animals with a VT of 10 ml/kg and a rate of 20/min by randomized application of VC and PC with I/E ratios of 1:2, 2:1, and 4:1. Despite liberal fluid administration, all ventilatory modes depressed cardiac output compared with preinjury values. However, gas exchange and hemodynamics did not differ among ventilation modes or I/E ratios.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
The effects of applied vs auto-PEEP on local lung unit pressure and volume in a four-unit lung model.
BACKGROUND: The application of positive end-expiratory pressure (PEEP) and maintenance of increased mean airway pressure (MAP) has been associated with improved oxygenation in adult respiratory distress syndrome. Recently, attention has been directed toward elevating MAP by establishing auto-PEEP when ventilating with an inverse inspiratory to expiratory ratio in opposition to applied PEEP. We theorized that FRC distribution and local lung unit end-expiratory pressure (EEP) would be different when equal levels of PEEP were established by applying PEEP or by producing auto-PEEP. METHODS: Using a four-chamber lung model with each chamber having a different time constant (TC), we applied equal levels of applied PEEP (I:E ratio 1:3) and auto-PEEP (I:E ratio 3:1) and evaluated local lung unit EEP and end expiratory lung volume (EELV). RESULTS: During all trials with applied PEEP, local lung unit EEP was equal to applied PEEP, whereas during auto-PEEP local EEP differed (p < 0.01). At a tracheal auto-PEEP level of 12.7 cm H2O, the lung unit with the longest TC (slow lung unit) had an EEP of 15.8 cm H2O, while the shortest TC unit (fast lung unit) had an EEP of 10.1 cm H2O (p < 0.01). Similarly, local EELVs were more maldistributed with auto-PEEP than with applied PEEP. At a tracheal PEEP level of 12.7 cm H2O, the EELV increase in the slow lung unit with auto-PEEP was 1,054 mL vs 918 with applied PEEP (p < 0.01), whereas the fast lung unit's EELV increase with auto-PEEP was 142 mL compared with 212 mL with applied PEEP (p < 0.01). CONCLUSION: Comparing equal levels of the auto-PEEP with applied PEEP, a greater maldistribution of local lung unit EEP and EELV was established with the auto-PEEP. During auto-PEEP, the greatest EEP and EELV occurred in the slow lung unit, and the lowest EEP and EELV developed in the fast lung unit.
Adult↗
Effects of disposable or interchangeable positive end-expiratory pressure valves on work of breathing during the application of continuous positive airway pressure.
OBJECTIVE: To determine which of a series of disposable or interchangeable positive end-expiratory pressure (PEEP) devices functions with the least imposition of inspiratory and expiratory work during continuous positive airway pressure. DESIGN: Prospective laboratory evaluation performed on a lung model. SETTING: Research laboratory at a university medical center. INTERVENTIONS: A spontaneously breathing lung model, created from a training test lung and a volume ventilator, were used to simulate a patient spontaneously breathing at a tidal volume of 0.4 L, peak inspiratory flow of 40 L/min, an inspiration/expiration ratio of 1:2, and a respiratory rate of 20 breaths/min. Ten PEEP valves attached to a continuous high-flow system were evaluated. MEASUREMENTS AND MAIN RESULTS: All of the PEEP valves studied imposed high levels of both inspiratory and expiratory work of breathing. The BE-171 and BE-142 valves (Instrumentation Industries) imposed the least amount of inspiratory work. In general, imposed inspiratory work accounted for approximately 70% to 80% of total imposed work of breathing. CONCLUSIONS: All of the disposable/interchangeable PEEP valves that were studied imposed a considerable amount of both inspiratory and expiratory work, even when the continuous flow provided exceeded the peak inspiratory flow demands of the lung model. The primary reason for the high imposed work levels is the high gas-flow resistance of all of the valves studied.
Airway Resistance↗
[Perioperative respiratory therapy lowers the risk of respiratory complications--fact or fiction?].
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Acute Disease↗
Prevention of pulmonary complications after abdominal surgery.
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Abdomen↗
[The effect of endonasal paranasal sinus surgery on lung function of patients with bronchial asthma].
Lung function tests of 13 patients suffering from manifest asthma and of 4 patients showing only bronchial hyperreactivity were performed before and on an average of 12 months after endonasal surgery of the paranasal sinuses. In the four subjects, bronchial hyperreactivity was no longer detectable postoperatively by provocation with carbachol. Five asthmatics could stop medication of 1 to 3 of their drugs, five others were able to reduce the dosage of one of their drugs to 50% or more. Lung function and medication was unchanged in two asthmatic patients, one patient had to add a drug to his medication while showing an unchanged lung function. In patients with asthma and chronic paranasal sinusitis, endoscopic endonasal sinus surgery (together with flanking measures, e.g. septal correction) is able to improve antiasthmatic therapy in a high percentage.
Adult↗
[Postoperative respiratory therapy using incentive spirometry].
The optimal methods of prophylaxis and therapy of postoperative respiratory complications in surgical patients are still open to discussion. In spite of numerous recent clinical investigations, there is still no specific and universally acceptable therapeutic concept. In our department, we identify patients at risk of pulmonary complications by adequate screening, i.e. medical history, physical examination, chest X-ray, and spirometry. In the postoperative period there are a sequence of stages starting with early mobilization, respiratory therapy (including incentive spirometry and IPPB), and when necessary, controlled mechanical ventilation. We have measured and documented the flows and volumes required of patients using various types of incentive spirometer. In addition, we review on the literature and describe our experience with the technique, handling, and organization of sustained maximal inspiration (SMI). After thoracic or major upper abdominal surgery, all lung volumes decrease due to impairment of rib cage movement, changes in chest wall muscle tone, an increase in lung recoil, and airway closure. At the end of each expiration some of the smallest airways collapse either partly or totally. This process continues to some extent until, normally, a deep breath recruits the alveoli. Sighs to the limit of total lung capacity or oscillations of the expiratory baseline ought to be responsible for this effect in healthy humans; the same purpose is intended in incentive spirometry. For this therapy, it is mandatory that the central airways are not occluded by mucus and that the patient is able to breath volumes exceeding his normal tidal volume.(ABSTRACT TRUNCATED AT 250 WORDS)
Humans↗