Respir Care Clin N Am
· 2001 Dec · PMID 11926763
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This article provides general guidelines for application and titration of HFOV; however, the use of HFOV in adults with ARDS still is considered experimental. Further evaluation of the efficacy of HFOV and potential impa...This article provides general guidelines for application and titration of HFOV; however, the use of HFOV in adults with ARDS still is considered experimental. Further evaluation of the efficacy of HFOV and potential impact on outcomes are needed in adults, particularly in the form of randomized, controlled trials.
Respir Care Clin N Am
· 2001 Dec · PMID 11926762
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Although not allowing one to state conclusively that a particular combination of approaches to CMV and adjuncts to CMV affect outcome, the results are encouraging. Independently, none of the modalities discussed-HFV, ECM...Although not allowing one to state conclusively that a particular combination of approaches to CMV and adjuncts to CMV affect outcome, the results are encouraging. Independently, none of the modalities discussed-HFV, ECMO, NO, or PLV-have shown a statistically significant improvement in outcome except NO. With NO, improvement is only in a small select group of patients; however, in combination there may be greater overall impact on outcome. With each of these modalities, more information is needed on how to apply each technique optimally. It is easy to see that modification of the experimental protocol in each study may have altered results. Clearly, more laboratory and clinical studies examining the combined use of these therapies are needed, as is identification of the specific patient populations where these combined therapies may be most effective.
Respir Care Clin N Am
· 2001 Dec · PMID 11926761
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The use of HFOV in adults is still in its infancy. There is, however, much promise to support further study of this ventilatory modality. Rescue case series have shown that HFOV is effective in improving gas exchange and...The use of HFOV in adults is still in its infancy. There is, however, much promise to support further study of this ventilatory modality. Rescue case series have shown that HFOV is effective in improving gas exchange and appears safe in this group of extremely ill patients. In addition, as evidence continues to mount regarding the importance of VILI and its mechanisms, HFOV provides a theoretically attractive alternative to conventional lung-protective ventilatory modes. When HFOV is used in adults, it should be in conjunction with an effort to recruit atelectatic lung units by employing higher mean airway pressures and weaning FIO2 before P(AW). HFOV could be used as one of a number of new therapies for the patient failing to oxygenate on CMV. Its routine use to prevent VILI cannot be recommended at this time, as no data are available. Further clinical studies potentially leading to a large randomized controlled trial of HFOV versus best conventional therapy appear worth pursuing.
Respir Care Clin N Am
· 2001 Dec · PMID 11926760
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HFOV is a mode of ventilation that can achieve oxygenation and ventilation while maintaining maximal lung recruitment on the deflation limb of its pressure-volume curve. The primary theoretical advantages of HFOV over CM...HFOV is a mode of ventilation that can achieve oxygenation and ventilation while maintaining maximal lung recruitment on the deflation limb of its pressure-volume curve. The primary theoretical advantages of HFOV over CMV in the management of acute lung injury are that HFOV allows adequate alveolar ventilation with minimal peak-trough pressure changes, provides lung recruitment, and avoids end-inspiratory overdistension of the relatively compliant nondependent lung. Taken together, the results of studies in animals, preterm and term neonates, and older pediatric patients reveal that an "open-lung" strategy, with the goal of a high end-expiratory lung volume, is safe and superior to CMV in both the short-term (rapidly improved oxygenation and/or ventilation) and longer-term (lower incidence of chronic lung disease). The improved longer-term clinical outcomes on HFOV are presumably because of less ventilator-induced lung injury. As experience with HFOV in older patients grows, ventilator technology matures, and understanding of the pathophysiology of acute respiratory distress syndrome (RDS) deepens, it is likely that HFOV will find widespread use for the management of respiratory failure caused by acute lung injury in patients from preterm neonates to adults.
Respir Care Clin N Am
· 2001 Dec · PMID 11926759
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Despite improvements in respiratory care, ventilator-induced lung injury remains an important cause of morbidity and mortality in neonates who require assisted ventilation. Animal data clearly demonstrate that high-frequ...Despite improvements in respiratory care, ventilator-induced lung injury remains an important cause of morbidity and mortality in neonates who require assisted ventilation. Animal data clearly demonstrate that high-frequency ventilation can be used successfully to reduce lung injury in experimental models of acute lung injury. These models and human research show that the efficacy of high-frequency ventilation is dependent on optimizing functional residual capacity and avoiding lung overinflation. When used with a strategy that promotes lung recruitment, high-frequency ventilation effectively reduces the occurrence of chronic lung disease and is not associated with significant brain injury. When used with a strategy that allows the lung to collapse or is associated with hyperventilation, however, high-frequency ventilation does not reduce lung injury and is associated with significant brain injury. Like every tool we use to support critically ill neonates, high-frequency ventilation needs a careful carpenter. As therapies and health care strategies evolve, there remains nothing more important than the health care team at the bedside. Critical evaluation of the patient and his or her response to the therapy being offered is essential to promotion of the patient health outcome.
Respir Care Clin N Am
· 2001 Dec · PMID 11926758
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High-frequency ventilation, including HFJV, is an interesting alternative approach to mechanical ventilatory support that may offer benefits in terms of improved gas exchange and lower maximal alveolar distending pressur...High-frequency ventilation, including HFJV, is an interesting alternative approach to mechanical ventilatory support that may offer benefits in terms of improved gas exchange and lower maximal alveolar distending pressures. Clinical data demonstrating improved outcome exist for neonatal and some forms of pediatric respiratory failure. No such data, however, exist for adults. Important complications can develop, and an extensive learning curve is required for operators to become skilled at delivering proper support safely. Presently, HFV should be limited to only specific applications (e.g., selected neonates, adult airway surgical procedures) and to centers skilled in its use. Considerably more data are required before extensive application, especially in the adult, is warranted.
Respir Care Clin N Am
· 2001 Dec · PMID 11926757
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Various technical approaches to high-frequency ventilation are available. Of these, HFOV is used most commonly. As high-frequency ventilation becomes increasingly used in the care of adult patients, the technical issues...Various technical approaches to high-frequency ventilation are available. Of these, HFOV is used most commonly. As high-frequency ventilation becomes increasingly used in the care of adult patients, the technical issues related to this therapy will become increasingly important.
Respir Care Clin N Am
· 2001 Dec · PMID 11926756
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HFV has been demonstrated to be a safe and effective way to ventilate and oxygenate patients, both short- and long-term, when used by experienced practitioners. It has carved out a niche in the specific management of res...HFV has been demonstrated to be a safe and effective way to ventilate and oxygenate patients, both short- and long-term, when used by experienced practitioners. It has carved out a niche in the specific management of respiratory problems in children and neonates; however, as understanding of the variables that independently contribute to VILI evolves, it is becoming clear that this mode of ventilation may be suited to the goals of lung protection. In addition, it is accepted also that initial assessment of HFV as a lung-protective strategy has failed to take into consideration significant variables that have been shown to be important in animal studies. This may have caused this mode of ventilation to be over looked as a possible strategy in the management of patients with severe lung disease. A number of trials are underway using ventilatory approaches based on current concepts of VILI, including improved CMV strategies. It is hoped that the results of these studies will identify the future role for HFV in the clinical setting.
Respir Care Clin N Am
· 2001 Dec · PMID 11926755
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High-frequency ventilation was first introduced 30 years ago as a method for reducing intrathoracic pressure during thoracic and laryngeal surgery. High-frequency oscillation was developed in the 1970's for the treatment...High-frequency ventilation was first introduced 30 years ago as a method for reducing intrathoracic pressure during thoracic and laryngeal surgery. High-frequency oscillation was developed in the 1970's for the treatment of lung disease of prematurity but is now used for acute hypoxemic respiratory failure in all ages. High-frequency jet ventilation is still most commonly used as a rescue therapy.
Respir Care Clin N Am
· 2001 Dec · PMID 11926754
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As with many innovative techniques in modern medicine, high-frequency ventilation (HFV) was discovered by accident rather than by design. Various modes of HFV also were developed concurrently, with little or no attempt t...As with many innovative techniques in modern medicine, high-frequency ventilation (HFV) was discovered by accident rather than by design. Various modes of HFV also were developed concurrently, with little or no attempt to standardize nomenclature. High-frequency ventilation developed along three main tracks, driven by somewhat different forces.
Respir Care Clin N Am
· 2001 Mar · PMID 11584807
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Sedation and analgesia will be required in the mechanically ventilated pediatric trauma patient. Adequate provision of both has a number of beneficial physiologic and psychologic effects. There are a number of categories...Sedation and analgesia will be required in the mechanically ventilated pediatric trauma patient. Adequate provision of both has a number of beneficial physiologic and psychologic effects. There are a number of categories of sedatives available for use. To provide optimal management and avoid adverse sequellae, an understanding of the pharmacology of these agents should guide their use in this group of patients, who are likely to have variable pharmacokinetic responses and therapeutic goals. Neuromuscular blockade is warranted in only a select population of mechanically ventilated ICU patients. Given newer ventilator technology and modes, it is certainly possible to achieve patient-ventilator synchrony with the use of sedation alone. Neuromuscular blockade is associated with a number of possible adverse effects, including prolonged weakness or paresis, and prohibits ongoing clinical assessment. When the use of this therapy is deemed necessary, it is again essential to understand the pharmacodynamics and pharmacokinetics of the available agents to avoid potential complications.
Respir Care Clin N Am
· 2001 Mar · PMID 11584806
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It is mandatory to evaluate and develop a plan for nutritional support for all injured children who are hospitalized. Although most childre" will rapidly resume normal oral intake, more severely injured children should b...It is mandatory to evaluate and develop a plan for nutritional support for all injured children who are hospitalized. Although most childre" will rapidly resume normal oral intake, more severely injured children should be started on parenteral or enteral nutrition as soon as possible after admission. The mode of delivery and composition of nutritional support differ depending on the clinical setting and can change during the recovery period. Development of an initial plan and modification of the plan depending on the child's response will most effectively meet the metabolic demands after injury.
Respir Care Clin N Am
· 2001 Mar · PMID 11584805
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Pediatric trauma management requires both operative and nonoperative (supportive) care. Fewer than 15% of pediatric trauma patients require surgery (Children's Hospital of Michigan Registry Data, excluding fractures), an...Pediatric trauma management requires both operative and nonoperative (supportive) care. Fewer than 15% of pediatric trauma patients require surgery (Children's Hospital of Michigan Registry Data, excluding fractures), and the primacy of closed head injury and the multisystem nature of pediatric trauma dictate assessment and therapy. Complications arise at every level, including fluid resuscitation (too much or too little), antibiotics (too late), or pain control (inadequate). The institution of mechanical ventilation that is usually life-saving carries its own risks including those associated with intubation (perforation, aspiration, pro longed endotracheal intubation (stricture, pneumonia), and barotrauma (ventilator-induced lung injury). Minor procedures, such as thoracentesis, chest tube insertion, and pericardiocentesis, can all be complicated by perforation and hemorrhage. Major interventions, including laparotomy and thoracotomy, can result in hemorrhage, air leak, abdominal compartment syndrome, phrenic nerve and thoracic duct injury, postoperative abscess, and septicemia. Transfusion, cardiopulmonary bypass, and invasive monitoring can result in coagulopathy and vascular injury. Prolonged resuscitation and operative explorations can cause hypothermia and coagulopathy and initiate a cascade of multiorgan failure and ARDS. There is no doubt that rapid evacuation, prompt resuscitation, and organized systems of pediatric trauma care have reduced the overall mortality of childhood trauma. The higher velocity of travel and an increasingly chaotic urban environment have resulted in more multitrauma cases and in injuries of higher severity requiring more sophisticated and complicated diagnostic and therapeutic modalities. Our ability to identify life-threatening injuries, to provide expedited and definitive care, and to reduce and detect the complications predicted by these injuries and their treatment will result in long-term improvements in survival and significant reductions in morbidity.
Respir Care Clin N Am
· 2001 Mar · PMID 11584804
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Meticulous care of the head-injured child revolves around the prevention of secondary injury. In no arena is this more crucial than in the respiratory support of the pediatric traumatic brain-injured patient. Careful att...Meticulous care of the head-injured child revolves around the prevention of secondary injury. In no arena is this more crucial than in the respiratory support of the pediatric traumatic brain-injured patient. Careful attention to intubation techniques, maintenance of adequate oxygen delivery, avoidance of hypoxia, and judicious use of PEEP and other respiratory therapeutics all can be invaluable in the care of the pediatric traumatic brain-injured patient and may ultimately enhance outcome in this sometimes devastating disease.
Respir Care Clin N Am
· 2001 Mar · PMID 11584803
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The successful management of pediatric thoracic injuries includes immediate and careful evaluation of the injury type and severity. Early treatment can be conservative in nature or require surgical management. Prompt int...The successful management of pediatric thoracic injuries includes immediate and careful evaluation of the injury type and severity. Early treatment can be conservative in nature or require surgical management. Prompt intervention can reduce morbidity and mortality rates, associated complications, and ensure optimal outcomes.
Respir Care Clin N Am
· 2001 Mar · PMID 11584802
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Traumatic airway injuries are rare in children, partly due to their unique anatomy. The larynx is well protected from direct blows behind the mandibular arch, and only a small portion of the trachea is unprotected above...Traumatic airway injuries are rare in children, partly due to their unique anatomy. The larynx is well protected from direct blows behind the mandibular arch, and only a small portion of the trachea is unprotected above the manubrium due to the relatively short neck. Furthermore, the tracheobronchial tree is less prone to injuries as compared with adults due to its elasticity. A high index of suspicion is thus needed to adequately diagnose and manage pediatric airway injuries. Laryngotracheal injuries in particular may present with discreet initial symptoms that if undiagnosed may rapidly progress to loss of airway. The most important signs of laryngeal injury include hoarseness and subcutaneous emphysema. Tracheobronchial injuries often present with dramatic symptoms, the most common being pneumothorax, which does not resolve after placement of chest tube, or large persistent air leaks. Endoscopy is mandatory on suspicion of injury to the larynx, trachea, or bronchi. CT scan may be helpful in determining the extent of injury to the larynx. Correct management of the airway in laryngotracheal injuries has a direct impact on morbidity and mortality. Endotracheal intubation over a flexible bronchoscope during spontaneous ventilation and in halothane anesthesia is the method of choice in children, but it should be performed in the operating room with the possibility of emergency tracheotomy. Cricothyroidotomy should be avoided in all laryngotracheal injuries because this method may aggravate the injury. Most laryngotracheal injuries in children can be conservatively managed. Extensive injuries, including displaced fractures of the cartilage, injuries to the recurrent nerves, and laryngotracheal separation, require surgical intervention. Injuries to bronchi and the thoracic trachea that do not cause a persistent air leak, and where the lungs expand completely after insertion of chest tubes, may be managed conservatively. All other injuries to the tracheobronchial tree should be repaired surgically as soon as feasible. Induction of anesthesia and opening of the chest may make ventilation difficult and are best managed by selective intubation of the contralateral lung. Long-term outcome after laryngeal, tracheal, and bronchial injuries in children, if managed swiftly and accurately, is usually excellent unless other injuries are present. The final result is improved by early recognition and early surgical intervention. These children need to be followed endoscopically for months and sometimes years in order to diagnose and treat stenoses as soon as they occur. Long-term pulmonary function has been shown to be excellent. Children with bilateral recurrent nerve paralysis may not fully recover voice or airway.
Respir Care Clin N Am
· 2001 Mar · PMID 11584801
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The initial evaluation and treatment of the pediatric trauma patient require an organized, thorough approach. All patients must be assumed to have multiple injuries until proven otherwise. Resuscitation efforts should be...The initial evaluation and treatment of the pediatric trauma patient require an organized, thorough approach. All patients must be assumed to have multiple injuries until proven otherwise. Resuscitation efforts should be aggressive to avoid the onset of irreversible shock. The ability to recognize and effectively treat shock are all that are required in the vast majority of injured patents in order to gain stability. The adequate assessment and treatment of the ABCs will provide adequate treatment of the patient's other injuries, leading to an overall improvement in morbidity and mortality. Thus, the ABCs play an essential role in the initial evaluation and treatment of the pediatric trauma patient.
Respir Care Clin N Am
· 2001 Sep · PMID 11517036
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Patients under pressure support ventilation sometimes encounter patient-ventilator asynchrony in the transition from inspiration to expiration, that is, expiratory asynchrony. This problem is caused by the incompatibilit...Patients under pressure support ventilation sometimes encounter patient-ventilator asynchrony in the transition from inspiration to expiration, that is, expiratory asynchrony. This problem is caused by the incompatibility of the fixed level of expiratory trigger sensitivity termination criteria (i.e., flow termination criteria) in the ICU ventilators to various patient conditions. The user-adjustable expiratory trigger sensitivity implemented in some newly released ventilators has been experienced to be difficult to use and unable to adapt ever-changing patient conditions without user intervention, although it provides more flexibility. This article elucidates the rationale for automatic control of the expiratory trigger sensitivity and evaluates the automation system with a bench setup. The evaluation data suggest that good expiratory synchronies can be achieved through automatic adjustments of expiratory trigger sensitivity.
Respir Care Clin N Am
· 2001 Sep · PMID 11517035
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In this article automatic tube compensation (ATC) is described with respect to working principle, to technical realization, and to clinical experience. ATC, based on an indirect closed-loop working principle, compensates...In this article automatic tube compensation (ATC) is described with respect to working principle, to technical realization, and to clinical experience. ATC, based on an indirect closed-loop working principle, compensates for the flow-dependent pressure drop across the tracheal tube during both inspiration and expiration. ATC reduces patient work of breathing, increases respiratory comfort, and allows prediction of successful extubation. ATC is not a stand-alone ventilatory mode, but rather a component of flow-proportional pressure support that can be combined with all conventional ventilatory modes.
Respir Care Clin N Am
· 2001 Sep · PMID 11517034
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Partial ventilatory support techniques are intended for patients who are unable to maintain a normal alveolar ventilation, despite normal central control for respiration. Proportional assist ventilation (PAV) is a novel...Partial ventilatory support techniques are intended for patients who are unable to maintain a normal alveolar ventilation, despite normal central control for respiration. Proportional assist ventilation (PAV) is a novel mode of partial ventilatory support in which the ventilator generates an instantaneous inspiratory pressure in proportion to the instantaneous effort of the patient. In theory, PAV should normalize the neuro-ventilatory coupling by making the ventilator an extension of patient's respiratory muscles, while leaving to the patient the entire control of all aspects of breathing. PAV, however, shares a common problem with the conventional partial ventilatory support modes. In mechanically ventilated patients, the respiratory system impedance may change over time. These changes may impair the good matching between ventilator output and patient's ventilatory demand and lead to patient-ventilator asynchrony. To take full advantage of PAV, the authors believe that PAV should continuously and automatically adapt to the respiratory system passive mechanics, assessed by continuous noninvasive measurement of total elastance and resistance.