Search

Objective: Tracheostomy is one of the most commonly performed surgical procedures in the critical care setting. The early use of tracheostomy as a method of primary airway management has been proposed as a means to decrease pulmonary morbidity and to shorten the number of ventilator, intensive care unit, and hospital days. We set out to (1) determine whether hypercarbia occurs during tracheostomy of the critically ill patient and (2) determine the extent to which the partial pressure of carbon dioxide in arterial blood (PaCO2) rises during percutaneous endoscopic, percutaneous Doppler, and standard surgical tracheostomy. Design: Prospective, open clinical trial. Setting: Surgical intensive care unit and operating room in teaching hospitals. Patients: During mechanical ventilation, patients underwent either percutaneous endoscopic (PET), percutaneous Doppler (PDT), or standard surgical tracheostomy (ST), based on surgeon preference. Arterial blood gas readings were obtained approximately every 4 min throughout each procedure. Measurements and results: All tracheostomies were successfully performed. No serious complications (including hypoxia) occurred during the study. Significant (p < 0.05 vs PDT and ST) hypercarbia (maximum Δ PaCO2 24 ± 3 mmHg) and acidosis (maximum Δ pH – 0.16 ± 0.02) developed during PET. The changes in PaCO2 and pH during PDT (maximum Δ PaCO2 8 ± 2 mmHg; maximum Δ pH – 0.07 ± 0.02) and ST (maximum Δ PaCO2 3 ± 1 mmHg; maximum ΔpH – 0.04 ± 0.01) were markedly less pronounced. Conclusions: Continuous bronchoscopy during percutaneous tracheostomy contributes significantly to early hypoventilation, hypercarbia, and respiratory acidosis during the procedure. Percutaneous tracheostomy, when performed using the Doppler ultrasound method to position the endotracheal tube, significantly reduces CO2 retention when compared to PET. Because of a possible rise in intracranial pressure, the potential for hypercarbia should be considered when choosing the method of tracheostomy in the critically ill and/or head-injured patient, where hypercarbia may be detrimental. If PET is to be performed, steps to minimize occult hypercarbia, such as using the smallest bronchoscope available, minimizing suctioning during bronchoscopy, and minimizing the length of time the bronchoscope is in the endotracheal tube, should be undertaken.

Although significant progress has been made in the treatment of patients with acute lung failure in the critical care setting, the mortality rate from acute lung injury and ARDS is unacceptably high, given the numbers of patients treated for these syndromes each year. The improved understanding of the pathophysiology of respiratory failure from basic science and clinical research is reflected in improved survival rates over the years. Advances in the mechanical ventilator (through microprocessor technology); biosurface technology; liquid ventilation; and, in some cases, returning to so-called "antiquated" practices of patient care (e.g., prone positioning) seem to have had an impact nonetheless. As refinement continues to occur in these areas, morbidity and mortality from lung failure will have a lesser impact on patients as physicians treat the consequences of organ failure in the ICU.

Acute or adult respiratory distress syndrome (ARDS) contributes to mortality and morbidity in the intensive care environment. Appropriate application of microprocessor-controlled mechanical ventilatory support, pathophysiology of the disease, and new pharmacologic modalities are currently being investigated. Mechanical ventilation is usually begun when respiratory failure is caused by alveolar hypoventilation or hypoxia. Primary choices for this therapy are control-mode ventilation, assist-control ventilation, pressure-control ventilation, intermittent mandatory ventilation, and synchronized intermittent mandatory ventilation with the addition of positive end-expiratory pressure. Patients who deteriorate despite these interventions may require alternative modes of ventilation. Pharmacologic agents in ARDS is important due to the multifactorial pathophysiologic and pharmacodynamic processes that are part of the disease. Clinical studies will continue to determine advantageous agents. Unfortunately, no convincing data exist that any pharmacologic or nonpharmacologic strategy is superior for the support of these patients or results in a better outcome than others.

Bronchoscopy has been incorporated as a useful adjunct to increase the safety and effectiveness of percutaneous endoscopic tracheostomy (PET). Insertion of the bronchoscope, along with the intraluminal dilators of the PET set, into the airway potentially leads to hypoventilation and hypercarbia during the procedure. Using continuous in-line arterial blood gas monitoring, we documented profound hypercarbia in two patients undergoing PET in the surgical ICU. In a third patient, the rise in PaCO2 was accompanied by a marked rise in intracranial pressure (ICP), and a corresponding fall in cerebral perfusion pressure. While transient hypercarbia seems well tolerated by most patients, this phenomenon and its effect on cerebral blood flow should be strongly considered before performing PET on the critically ill patient with evidence of elevated ICP.

This study was based on an analysis of essays written by 47 teacher education students in response to the question, "If you could live your high school days over again, what, if anything, would you change?" The responses were organized into 20 different categories and tabulated according to students' age and sex. In retrospect, 38% of these students would have improved their attitude toward high school. Thirty-six percent indicated that high school was a positive experience, though this attitude was often unrelated to academic achievement. The responses strongly suggest that for many high school students, general attitude toward school affects achievement more than do attitudes toward specific school characteristics.

Percutaneous dilatational tracheotomy is a safe, efficient procedure for elective tracheostomy placement. It is not a technique for emergency tracheotomy. It should be performed only by surgeons experienced in conventional tracheotomy. The advantages of placement at the bedside, speed, and relative inexpense make it attractive in the care of critically ill patients.

Extracorporeal membrane oxygenation is now standard treatment of severe respiratory failure in newborn infants in our center (200 cases) and worldwide (over 2500 cases), but there are few reports of such trials in older children. We reviewed our experience with extracorporeal membrane oxygenation in 33 children aged 1 week to 18 years between 1971 and 1989. The modality was used when all other treatment failed. Extracorporeal membrane oxygenation provided excellent cardiopulmonary support for 1 to 25 days (average 7 1/2 days). The survival rate was 25% for cardiac support patients and 47% for respiratory failure patients (36% overall survival). Mechanical complications included membrane lung failure, tubing rupture, and pump failure, all managed without mortality. Physiologic complications included bleeding, pneumothorax, cardiac arrest, renal failure, hepatic failure, and brain injury. The major cause of death was irreversible injury to lung, heart, or brain. Extracorporeal life support is a reasonable approach for children with serious but reversible cardiopulmonary failure.

In view of earlier results obtained with rodents, the present study was designed to investigate the effect of acute zinc deprivation in man on plasma zinc concentration and the response ofplatelets to aggregating agents. Three adult men consumed a formula diet based largely on soybean protein for 12 to 14 days. During the control period the diet was supplemented with 12 mg zinc per day. Without supplementation the diet supplied approximately 0.5 mg zinc per 3.0 Mcal; it contained 0.7 ppm zinc, and 0.2% phytate. After removal of the zinc supplement plasma zinc dropped rapidly and reached a minimum by the 5th day. There was a wide diurnal variation in plasma zinc concentration in one subject with the overnight fasting value being the highest and decreasing soon after the morning meal. Platelet aggregation in response to ADP and arachidonate was impaired when plasma zinc was 60 �sg/dl or less and was restored to normal within 19 h of oral zinc supplementation. These results demonstrate that plasma zinc can be rapidly decreased by dietary zinc deprivation and that extracellular zinc plays an important role in platelet aggrega- tion. Am J Clin Nutr l982;35:ll3-l19.

Eleven young men were confined to a metabolic research unit for 90 d to determine the effect of the level of dietary copper on absorption and retention. Cu absorption was determined by feeding the stable isotope 65Cu. Absorption and retention averaged 36.3 +/- 1.3% and 0.17 mg/d, respectively, with an adequate-Cu diet (1.68 mg/d). Absorption averaged 55.6 +/- 0.9% and retention averaged -0.316 mg/d for 6 d and 0.093 mg/d for the next 36 d of a low-Cu diet (0.785 mg/d). Absorption averaged 12.4 +/- 0.9% with a high-Cu diet (7.53 mg/d) and retention was strongly positive at first, decreasing linearly with time. The study demonstrated that Cu absorption is strongly dependent on dietary Cu level and that Cu balance can be achieved by most young men from a diet of 0.8 mg Cu/d. These results suggest that current dietary Cu recommendations may be higher than necessary. The apparent regulation of Cu absorption and endogenous losses would tend to protect humans from Cu deficiency and toxicity.

The authors designed and tested a 14F outside diameter thin-walled double lumen catheter (DLC) for neonatal venovenous (VV) extracorporeal membrane oxygenation (ECMO). In vitro tests with water and dye solution showed capacity of the drainage lumen was 1,096 ml/min at 100 cm siphon, and pressure drop across the perfusion lumen was 300 mmHg at 500 ml/min flow. Recirculation at 500 ml/min flow ranged from 5 to 29%, depending upon simulated cardiac output. The highest serum hemoglobin during 12 hour 400 ml/min flow VV bypass in five dogs was 49 mg/dl. Typical oxygen transport in four dogs was 25 cc/min at 400 ml/min flow. This catheter is well suited for clinical VV ECMO in neonates.

After satisfactory development and testing of a polyurethane 14 Fr double lumen catheter, we used this device for venovenous extracorporeal life support in neonates who had respiratory failure. This catheter was designed for single site cannulation of the internal jugular vein, thereby sparing the carotid artery from ligation. Cannulation was successful in 17 of 21 neonates, with 15 successful venovenous runs, whereas 2 of the 17 patients were converted to venoarterial bypass because of inadequate support. Oxygenation and CO2 removal were adequate in the remaining patients. Average time on bypass was 111 hours. All 15 patients survived, and exploration of the cannulation site for bleeding was required in three patients. Preoxygenator pressure, recirculation of oxygenated blood, and hemolysis were all within acceptable levels during each run. Venovenous extracorporeal life support with the double lumen catheter can replace venoarterial access in most cases of neonatal respiratory failure.

The inadequacy of a definition of attitudinal terms has complicated the interpretation of many food habit studies. This review has focused on the multidimensional character of the word "attitude" as an aid to gaining insight into food habit development and change. The five definitional categories presented (attitudes as preferences, as overt food behavior, as willingness or ability to change, as agreement among family members, and as complexity of meanings) do not preclude other definitions. Knowledge of attitude studies can foster understanding of the link between nutritional knowledge and actual behavior, as well as help practitioners to be more effective in formulating objectives and developing techniques for nutrition education. The various dimensions and meanings of attitudes indicate the need for continued research to clarify the effect of well defined attitude variables on food habits.