Treatment of forearm fractures.

Fractures of the forearm represent common injuries. Understanding the anatomy and function of the radius, ulna, interosseous membrane, proximal and distal radioulnar joints is critical to appropriate management. Diagnosis can readily be made by examination and radiographs. Well established surgical approaches including the anterior Henry, dorsal Thompson, and ulnar approaches provide excellent access to both the radius and ulna. Multiple fracture patterns are recognized including isolated radius and ulna fractures, combined fractures, Galeazzi fractures, and Monteggia fractures. Surgical management regularly requires open reduction internal fixation with plates (DCP) and screws with vigilance being paid to stable reduction of the proximal and distal radioulnar joints. New directions in the management of forearm fractures include the use of intramedullary fixation and locking plate technology.

Respiratory function during pressure support ventilation.

Pressure support ventilation (PSV) is a pressure assist form of mechanical ventilatory support that augments the patient's spontaneous inspiratory efforts with a clinician selected level of positive airway pressure. To understand the effects of PSV on respiratory function, experiments were performed on 15 stable patients requiring synchronized intermittent mandatory ventilation (SIMV), as well as on a mechanical model simulating these patients' ventilatory systems. In the clinical study, gas exchange, airway pressures, blood pressure and heart rate were measured while SIMV was replaced by enough PSV to approximate the baseline SIMV tidal volume (VT). Measurements were repeated while this PSV level was then reduced in three 5 cm H2O steps every 10 to 15 minutes. It was found that PSV was a reasonable form of mechanical ventilatory support in patients with spontaneous ventilatory drives. It improves patient comfort, reduces the patient's ventilatory work, and provides a more balanced pressure and volume change form of muscle work to the patient. The clinical significance of these properties during the weaning process remain to be determined.

Effects of initial flow rate and breath termination criteria on pressure support ventilation.

To assess whether adjustments in the initial flow rate or breath termination criteria affected patient-ventilator synchrony, we studied the ventilatory pattern response to PS in 33 patients under two sets of circumstances: during seven different levels of delivered initial PS flow and during PS termination at 50 percent and at 25 percent of peak flow. In the study on initial PS flow, we found the following: (a) an optimal initial PS flow could be defined for a given level of PS that resulted in the patient obtaining maximal pressure and volume from the ventilator; (b) initial PS flows above and below this optimal flow were associated with faster breathing frequencies, shorter inspiratory times, smaller tidal volumes and a tendency for airway pressure to not reach the selected PS level; and (c) optimal initial PS flow was fastest in patients with the lowest compliances and the most active ventilatory drives. Changing PS termination criteria from 50 to 25 percent of peak flow had minimal effects on the ventilatory pattern or synchrony. We conclude that the initial PS flow to achieve the selected PS level is important in patient-ventilator synchrony but that termination criteria set between 25 and 50 percent of peak flow is not.

Applied PEEP during pressure support reduces the inspiratory threshold load of intrinsic PEEP.

OBJECTIVES: Mechanical ventilation in patients with obstructive airway disease (OAD) is associated with the development of dynamic hyperinflation and intrinsic positive end-expiratory pressure (PEEPi). One of the effects of this form of PEEPi is to act as an inspiratory threshold load that can produce ineffective breath triggering, dyspnea, and muscle fatigue. Recently it has been shown that applying PEEP in the ventilator circuit can reduce this imposed triggering load. We wished to investigate this further by studying patients with OAD being weaned with pressure support (PS) ventilation. Our first objective was to determine the prevalence and magnitude of this form of PEEPi in OAD patients who were clinically judged to be capable of triggering mechanical ventilatory breaths. Our second objective was to attempt to reduce the triggering load by applying circuit PEEP and then observe the response of patient-ventilator interactions during the patient-triggered, pressure-limited PS breath. DESIGN: Thirteen random patients with OAD who were receiving PS ventilation were studied by measuring airway pressures, airway gas flow, baseline esophageal pressure, esophageal pressure time products (PTP), and esophageal pressure changes before ventilator gas delivery began (delta Pes taken to represent PEEPi). Measurements were made at baseline and after stepwise increases in circuit PEEP up to the PEEPi. RESULTS: We found measurable PEEPi in all patients (average +/- SD of 9.54 +/- 4.3 cm H2O) and it was > 10 cm H2O in seven patients. As would be predicted, we observed progressive reductions in PEEPi as applied PEEP was given. We also observed that the component of patient effort (PTP) related to overcoming PEEPi also decreased, but the PTP related to tidal volume (VT) did not. The VT associated with the set PS thus did not change with application of PEEP, nor did the breathing frequency. CONCLUSION: PEEPi is common in OAD patients receiving mechanical ventilatory support. The imposed triggering load from PEEPi can be offset to large extent by circuit PEEP approaching the baseline PEEPi. Although total patient effort substantially falls with applied PEEP, the patient effort that combine with PS to effect VT does not.

Normal values for single exhalation diffusing capacity and pulmonary capillary blood flow in sitting, supine positions, and during mild exercise.

Previous approaches to the measurements of pulmonary diffusing capacity (DL) and pulmonary capillary blood flow (QC) utilized either the rebreathing or the single inhalation technique in conjunction with radioisotope gas and mass spectrometry. In the present study, we utilized a newly developed rapid infrared analyzer in conjunction with the slow single exhalation technique on 100 healthy volunteers to establish normal values for DL and QC under sitting, supine, and exercise conditions. The exercise level was determined by a target heart rate: HRex = ([HRmax - HRrest]/3) + HRrest. Prediction equations based on regressions on age, sex, height, or weight were then computed for sitting, supine, and exercise values. We found that mean DL and QC increased by approximately 12 percent and 8 percent, respectively, from sitting to supine posture, and by approximately 30 percent and 100 percent, respectively, from sitting (rest) to mild exercise. These results provided a database for further studies in the single exhalation method in various clinical settings.

Rest and exercise cardiac output and diffusing capacity assessed by a single slow exhalation of methane, acetylene, and carbon monoxide.

To study rest and exercise pulmonary capillary blood flow (Qc) and diffusing capacity (DLexh) assessed by the rapid analysis of methane, acetylene, and carbon monoxide during a single, slow exhalation, we evaluated 36 subjects during first-pass radionuclide angiography (RNA). At rest (N = 36) and at exercise (N = 21) there was no difference in the respective measurements of cardiac output (Qc = 6.0 +/- 1.7 and CORNA = 6.9 +/- 2.5 at rest; Qc = 13.7 +/- 3.2 and CORNA = 14.5 +/- 4.1 at exercise, L/min, mean +/- SD, r = .80). Mild maldistribution of ventilation, as manifested by an increased phase 3 alveolar slope for methane (CH4 slope), did not significantly influence the results. CH4 slope and DLexh did increase significantly with exercise, while total lung capacity remained unchanged (CH4 slope: 6.2 +/- 5.0 vs 12.5 +/- 6.8% delta CH4/L, mean +/- SD, p less than 0.001; Dsb: 27.7 +/- 9.2 vs 42.0 +/- 17.9 ml/min/mm Hg, mean +/- SD, p less than 0.001; TLC: 5.47 +/- .20 vs 5.96 +/- 1.20 L, mean +/- SD). DLexh was related to CORNA (r = .68) and RNA stroke volume (r = .50). Qc was significantly less than CORNA in the subset of studies with valvular regurgitation (VHD) (N = 7). On the other hand, Qc was significantly greater than CORNA in the setting of coronary artery disease (CAD) and severe wall motion abnormalities (N = 7). These differences may be attributed to regurgitant fractions in VHD, and the influence of wall motion abnormalities on the estimation of left ventricular volume by the area-length method in CAD. These two noninvasive methods compare well at rest and exercise in clinical subjects and may provide complementary information in certain cardiopulmonary diseases.

Pulmonary function in mechanically-ventilated patients during 24-hour use of a hygroscopic condensor humidifier.

Hygroscopic condensor humidifiers (HCH) are reportedly capable of humidifying even the driest of ventilator source gases with at least 30 mg H2O/liter of ventilation. To assess the adequacy of the HCH during mechanical ventilation, we studied 26 patients over a 72-hour period (alternating 24-hour periods of humidification by a conventional cascade and the HCH). In these patients, we found no significant difference in static lung compliance, airway resistance, PaO2, and PaCO2 on either system. Additionally, estimates of sputum volume (over a four-hour collection period) and clearance of aerosolized 99mTc labelled DTPA (in five of these patients) also showed no significant differences between the two systems. We conclude that the HCH is capable of supplying necessary heat and moisture to most mechanically-ventilated patients for at least a period of 24 hours.

Psychological outcomes of a pulmonary rehabilitation program.

This study assessed physiologic, psychological, and cognitive functioning in outpatients with COPD. Sixty-four subjects, 53 to 82 years of age, participated in the 30-day exercise rehabilitation program. The program consisted of exercise, education and psychosocial counselling. Participants were assessed prior to beginning the program and at the end of 30 days. Assessments at both times included physiologic functioning (bicycle ergometry testing, pulmonary function tests, 12-min walk), psychological well-being (anxiety, depression, psychiatric symptoms, perceived well-being) and an abbreviated neuropsychological test battery. Results indicate significant improvement in physical endurance and pulmonary function, significant reductions in symptoms of depression and anxiety, and improvement in measures of general well-being and neuropsychological functioning. The study suggests that exercise rehabilitation of older adults with COPD contributes not only to improvements in physical functioning and endurance, but also to enhanced cognitive functioning and psychological well-being.

Psychological and cognitive outcomes of a randomized trial of exercise among patients with chronic obstructive pulmonary disease.

Exercise rehabilitation is recommended increasingly for patients with chronic obstructive pulmonary disease (COPD). This study examined the effect of exercise and education on 79 older adults (M age = 66.6 +/- 6.5 years; 53% female) with COPD, randomly assigned to 10 weeks of (a) exercise, education, and stress management (EXESM; n = 29); (b) education and stress management (ESM; n = 25); or (c) waiting list (WL; n = 25). EXESM included 37 sessions of exercise, 16 educational lectures, and 10 weekly stress management classes. ESM included only the 16 lectures and 10 stress management classes. Before and after the intervention, assessments were conducted of physiological functioning (pulmonary function, exercise endurance), psychological well-being (depression, anxiety, quality of life), and cognitive functioning (attention, motor speed, mental efficiency, verbal processing). Repeated measures multivariate analysis of variance indicated that EXESM participants experienced changes not observed among ESM and WL participants, including improved endurance, reduced anxiety, and improved cognitive performance (verbal fluency).

New modes of mechanical ventilation.

Many new approaches to mechanical ventilation have been developed. This article discusses these new strategies and modes. These include lung protection conventional ventilation strategies, long inspiratory time strategies, pressure-targeted breath enhancements, airway pressure-related release ventilation, and proportional-assist ventilation.

New forms of mechanical ventilation in the adult.

Although mechanical ventilatory support in the 1980s clearly provides adequate gas exchange with minimal side effects, there remains a need for ventilation and oxygenation in those with severe gas exchange abnormalities, for reduced airway pressure effects in those at risk for barotrauma, for a better muscle reconditioning approach in those with muscle dysfunction, and for better ventilator-patient interactions (synchrony) in many patients receiving mechanical ventilatory support. The new approaches outlined previously address these issues. However, research and development for new and better techniques are needed. Specific areas that require better understanding include the effects of intrathoracic pressure on the lungs and the circulation, the matching of ventilation and perfusion under different support modes, the function of the respiratory muscles during fatigue and recovery, and the ventilatory reflexes operational during mechanical ventilation. Only with this information can we design the optimal ventilatory support system.

Oxygen therapy and exercise response in lung disease.

Lung disease affects exercise performance through a number of mechanisms, including hypoxemia, abnormal ventilatory mechanics, abnormal ventilatory muscles, abnormal ventilatory patterns, abnormal right heart function and subjective dyspnea. Supplemental oxygen improves hypoxemia and thus improves exercise impairment resulting from hypoxemia-related reductions in oxygen delivery. Supplemental oxygen also reduces exercise ventilation. This, in turn, reduces ventilatory muscle work, and the concomitant permissive hypercapnia may have beneficial effects at the cellular level. Additionally, in obstructive disease patients, an improved ventilatory pattern may reduce air trapping. Supplemental oxygen may also improve right ventricular dysfunction in patients with underlying right ventricular dysfunction. Finally, supplemental oxygen may reduce dyspnea caused by oxygen-related carotid body activity. Important questions remain. First, is long-term oxygen use of benefit in patients with only exercise hypoxemia? Second, is exercise conditioning possible in patients with exercise hypoxemia? Third, does supplemental oxygen enhance exercise conditioning efforts in those patients with CLD but without exercise hypoxemia? If the answer to this last question is yes, what selection criteria should be used to identify those who would benefit? The answers to all of these questions will have enormous impact on our approach to the optimal management of CLD patients.

Long-term oxygen therapy: conference summary.

With Jan's presentation, the conference concluded. In looking back on it, I think it is obvious that the group heard a very comprehensive, state-of-the-art review of this very important topic. Obviously, LTOT has enormous clinical and financial impact for millions of patients around the world. Indeed, LTOT is one of the few therapies available that has clearly been shown in randomized controlled trials to impact mortality. There are many questions that remain, however. To me, the most important of these questions involve the diagnosis and management of patients who do not have resting hypoxemia but who do have NOD and/or XOD. How aggressively should we "screen" for these conditions? If we find them, do we treat continuously or just during the hypoxemic episodes? What is the role of supplemental oxygen during rehabilitative exercises (including usage in patients who don't become hypoxemic)? The answers to these questions will clearly have substantial clinical and financial impact. Other memorable aspects of this conference included the tireless efforts of Ray Masferrer to pull this conference off, the special camaraderie of the participants that made the discussions so productive, and the lovely location that gave the conference an atmosphere of high quality. I'd like to recognize and thank two important groups. First, the American Association for Respiratory Care did a superb job of organizing the conference and providing the journal Respiratory Care as a forum to publish the proceedings. Second, our 3 industry sponsors not only provided critical funding support but also gave the group important perspectives during many of the discussions. These kinds of industry-profession collaborations benefit everyone. Finally, I'd like to extend my congratulations to all the speakers for jobs well done and to thank them for making my job as summarizer an enjoyable one.

Chronic obstructive pulmonary disease management: the evidence base.

In long-term management of stable chronic obstructive pulmonary disease (COPD), a number of medications improve pulmonary function test results. The long-term clinical benefits of those drugs would seem intuitive, but there is very little strong evidence that long-term outcomes in COPD are substantially affected by those drugs. Nevertheless, symptom improvement such as dyspnea reduction is certainly strong reason to use those agents. The 2 most compelling bodies of evidence in stable COPD are for oxygen therapy in the chronically hypoxemic patient and pulmonary rehabilitation to improve exercise tolerance and dyspnea. Inhaled corticosteroids also appear to be useful in patients at risk for frequent exacerbations. In acute exacerbations, the rationale for therapy comes in part from the large body of literature regarding acute asthma therapy. Bronchodilator therapy and corticosteroids both seem to reduce the severity and the duration of exacerbations. Moreover, routine antibiotic use seems beneficial, and the role of noninvasive positive-pressure ventilation with patients suffering impending respiratory failure from acute COPD exacerbations is well supported by the literature.

Intratracheal catheters as drug delivery systems.

Medication delivery into the lungs can be used to provide a high therapeutic index for agents targeted to specific lung diseases. In addition, the lung can be used as a portal of entry for other agents targeted to systemic diseases. Delivery of medications into the lung can be accomplished by either instillation or aerosolization. Instillation approaches are limited by the fluid volume that can be given safely, and instilled liquids distribute according to gravity. In contrast, aerosolization approaches can deliver larger volumes over longer periods and aerosols distribute according to ventilation. In the mechanically ventilated patient, externally generated aerosols have very poor lung delivery because the endotracheal tube functions as a barrier to aerosol passage. Novel aerosol generating systems at the ends of small-diameter catheters that can be placed into the trachea (or beyond) are being developed to address this. In vitro testing has shown these systems to be capable of producing appropriately sized particles, with high rates of lung deposition. These catheters could be coupled with tracheal gas insufflation systems, not only to deliver therapeutic aerosols but also to create water aerosols to supply necessary humidification during tracheal gas insufflation.

Aerosolized medications for altering lung surface active properties.

Surface active material is important in the function of both the infant and adult lung. In the premature infant, surfactant depletion results in the requirement for very high distending pressures to open alveoli. As a consequence, shunt, hypoxemia, and right ventricular dysfunction occur. Surfactant replacement, especially by the direct instillation approach, has been proven effective in improving clinical outcome under these circumstances. Problems with surfactant instillation include the "fluid bolus" effect and concerns about optimal distribution of the instilled material. Recent improvements in aerosol systems have created interest in using aerosol delivery to reduce the total dose of surfactant required to treat RDS. In adult acute lung injury, surfactant dysfunction, rather than depletion, is the problem. Simple phospholipid replacement strategies thus may not be effective. Instead, surfactant delivery strategies aimed at regional targeting with surfactants having the necessary associated proteins may be the goal in ARDS. In adults, several instillation trials are underway, but there is also a hope that an aerosol strategy might also be tried. The aerosol route may be particularly useful if a high-efficiency aerosol system (eg, one distal to an endotracheal tube) can be shown to be effective. Other surface active materials exist and there are small studies showing benefit when large instilled doses of these materials are given. These materials, however, have never been studied as aerosols.

Analysis of an endotracheal intubation service provided by respiratory care practitioners.

UNLABELLED: Our Respiratory Care Services Department provides an endotracheal intubation service that responds to all intubation requests. Intubation is performed by registered respiratory therapists who complete an 8-hour training program, advanced cardiac life support (ACLS) training and certification, and clinical performance of intubation with supervision. The goals of this service are (1) to provide competent persons for performing this service, (2) to assure a rapid response time, and (3) to be cost-effective. EVALUATION METHODS: A retrospective analysis of our service was conducted over a 1-year period (7/90 to 6/91), and calculations were made of the intubation success rate and complication rate. RESULTS: Of the 833 total intubations, 791 were successfully performed by respiratory care practitioners; 730 of those successful intubations (92.3%) were accomplished in fewer than 3 attempts. Recognized complications occurred in 96 intubations (12.1%) and included oral bleeding, vomiting, and short periods of oxygen desaturation. In the 5.1% (42) of the patients not intubated by our service, 22 required heavy sedation, and an anesthesiologist was consulted; 17 patients were intubated by other physicians; and 3 tracheotomies were performed. Multiple intubation attempts were a result of secretions, induced bradycardia, blade-light malfunction, damaged cuff, and esophageal intubations. CONCLUSION: Respiratory Care Services can provide an effective intubation service. Cost savings were realized by centralizing equipment.

Hemodynamic monitoring in respiratory care.

Continuous, invasive hemodynamic monitoring of patients in respiratory failure is an important aspect of total respiratory care. Understanding both the technical and physiological principles underlying hemodynamic monitoring is therefore important for respiratory care practitioners. This review is designed to meet this need by (1) addressing the technical aspects of hemodynamic monitoring (catheters, transducers, and monitors), (2) discussing the determinants of commonly measured hemodynamic variables (intravascular pressures and cardiac output), and (3) offering an orderly approach to hemodynamic data that allows for rapid determination of the patient's physiologic state and appropriate diagnostic possibilities. These principles are illustrated by five examples.

Epidemiology, pathophysiology and clinical presentation of gram-negative sepsis.

OBJECTIVE: To review the epidemiology and pathophysiology of gram-negative sepsis and the new consensus terminology describing the clinical signs of sepsis. DATA SOURCES: Review of the medical literature and compiled data from animal and clinical trials. PARTICIPANTS: Members of the Society of Critical Care Medicine, American College of Chest Physicians and American Association of Critical-Care Nurses with expertise on the subject of sepsis and its complications. RESULTS: Preconference and general sessions were offered at the National Teaching Institutes of the American Association of Critical-Care Nurses, with the goal of clarifying the epidemiology, risk factors and pathophysiology of gram-negative sepsis. In addition, current terminology and new (1992) consensus terminology describing the clinical signs of sepsis were presented. Special emphasis was placed on the role of the healthcare provider in the prevention and recognition of sepsis and the role of the septic mediators in the septic cascade. CONCLUSIONS: If the incidence of sepsis is to be reduced, the healthcare provider must be aware of the risk factors for sepsis and methods of reducing nosocomial infections. A thorough understanding of the role of mediators and consensus terminology used to describe sepsis, severe sepsis, septic shock and multiple organ dysfunction syndrome is necessary to recognize early or progressive signs of sepsis and to initiate state-of-the-art therapy.

Asbestos content of bronchoalveolar lavage fluid. A comparison of light and scanning electron microscopic analysis.

We studied the asbestos content of bronchoalveolar lavage fluid (BALF) from 9 patients with asbestosis, 17 asbestos exposed but without asbestosis, 15 with idiopathic pulmonary fibrosis (IPF) and 9 nonexposed volunteers. The cellular lavage pellet was digested and filtered for asbestos body (AB) quantification by light microscopy (LM) and analysis of numbers and types of uncoated fibers (UF) by scanning electron microscopy (SEM) and energy dispersive x-ray analysis. BALF of asbestosis patients had significantly higher AB content than that of the combined IPF and volunteer groups. The UF content as determined by SEM was similar in all four groups. Commercial amphiboles (amosite or crocidolite) were identified more frequently in BALF from patients with asbestosis than from the other groups. ABs were detected by SEM only in highly exposed individuals. We conclude that the findings of > 1 AB per 10(6) cells or 1 AB/mL BALF by LM and of ABs or commercial amphibole fibers by SEM are indicative of considerable exposure to asbestos in the majority of cases.