Advances in artificial airway management.

This article has reviewed some of the current airway management practices as well as technologic advances in adult tracheal tube design in the critically ill patient. Although the primary goals of airway protection and facilitation of positive pressure ventilation remain unchanged, a better understanding of the limitations of tracheal tubes, as well as strategies for optimized airway management, is critical. Such information is needed in order to reduce or avoid potential complications associated with tracheal tubes or similar airway devices.

Noninvasive respiratory monitoring.

Advances in technology now permit a variety of noninvasive respiratory monitoring options for clinicians. Perhaps a more complex issue is determining how much monitoring is needed as part of routine patient care. Often, practitioners take a "more is better" approach. This reasoning is justified in critical care, because, in theory, the more information clinicians have available to them, the more likely they are to make accurate assessments and proper therapeutic interventions. If one fails to properly understand the physiologic significance and clinical limitations of the numbers or waveforms from the monitor, however, patient care may not improve and, even worse, may be compromised. Therefore, proper training in all aspects of respiratory monitoring should be a basic and fundamental component of any critical care nurse training program. There are important cost considerations to be taken into account with continuous respiratory monitoring. The financial impact as it relates to care of the critically ill patient is often difficult to assess. Issues of cost-effectiveness are often justified because of the complex nature of caring for these patients and their need for intensive clinical observation and evaluation. The fact that many aspects of cardiopulmonary assessment can now be determined noninvasively is an important advantage over more invasive technologies and their associated risks. Clearly, monitoring techniques such as pulse oximetry and capnography do not eliminate the need for arterial blood gases and other invasive cardiopulmonary monitoring techniques. Rather, when appropriately applied, noninvasive monitoring has the potential to reduce the frequency of certain invasive procedures and still provide valuable information to nurses and other health care practitioners.

Measurement of glucose in tracheobronchial secretions to detect aspiration of enteral feedings.

OBJECTIVES: To determine (1) the relationship between results from 2 methods to measure glucose in tracheobronchial aspirates, (2) the effect of blood glucose levels on tracheobronchial glucose levels, and (3) the relationship between results from 2 methods to measure glucose in selected enteral formulas. DESIGN: Descriptive. SETTING: Two midwestern acute-care hospitals, a research laboratory, and a clinical laboratory. PATIENTS: Sixty-two acutely ill adult subjects with artificial airways whose secretions required frequent suctioning for therapeutic purposes; 53 of these 62 patients also required capillary blood glucose measurements for therapeutic purposes. OUTCOME MEASURES: Glucose concentrations in tracheobronchial secretions, capillary blood, and selected enteral formulas. INTERVENTION: None. RESULTS: Measures of glucose content made on 75 split samples of tracheobronchial secretions by 2 methods (glucose oxidase reagent strips and a laboratory assay) were highly correlated (ri = 0.94; P < .001) and mean readings were not statistically different (P = .17). Sixty-six capillary blood glucose readings made within 5 minutes of tracheobronchal suctioning correlated poorly with the glucose content in the tracheobronchial aspirates (r = 0.12; P = .36). Glucose concentrations in 22 enteral formulas determined by 2 methods correlated highly (r = 0.95; P < .001). Glucose concentrations were higher with the laboratory assay (259.6 +/- 206.3 mg/dL) than with glucose oxidase reagent strips (188.6 +/- 157.5 mg/dL). CONCLUSION: It appears appropriate to use glucose oxidase reagent strips to estimate glucose concentrations in tracheobronchial fluid. Elevated blood glucose levels apparently do not have a major effect on the glucose content in tracheobronchial fluid. Although mean glucose concentrations in the 22 formulas were higher with the laboratory assay, the readings were sufficiently similar to allow using glucose oxidase reagent strips to give a good estimation of the formulas' glucose content.

A randomized, controlled trial of protocol-directed versus physician-directed weaning from mechanical ventilation.

OBJECTIVE: To compare a practice of protocol-directed weaning from mechanical ventilation implemented by nurses and respiratory therapists with traditional physician-directed weaning. DESIGN: Randomized, controlled trial. SETTING: Medical and surgical intensive care units in two university-affiliated teaching hospitals. PATIENTS: Patients requiring mechanical ventilation (n = 357). INTERVENTIONS: Patients were randomly assigned to receive either protocol-directed (n = 179) or physician-directed (n = 178) weaning from mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: The primary outcome measure was the duration of mechanical ventilation from tracheal intubation until discontinuation of mechanical ventilation. Other outcome measures included need for reintubation, length of hospital stay, hospital mortality rate, and hospital costs. The median duration of mechanical ventilation was 35 hrs for the protocol-directed group (first quartile 15 hrs; third quartile 114 hrs) compared with 44 hrs for the physician-directed group (first quartile 21 hrs; third quartile 209 hrs). Kaplan-Meier analysis demonstrated that patients randomized to protocol-directed weaning had significantly shorter durations of mechanical ventilation compared with patients randomized to physician-directed weaning (chi 2 = 3.62, p = .057, log-rank test; chi 2 = 5.12, p = .024, Wilcoxon test). Cox proportional-hazards regression analysis, adjusting for other covariates, showed that the rate of successful weaning was significantly greater for patients receiving protocol-directed weaning compared with patients receiving physician-directed weaning (risk ratio 1.31; 95% confidence interval 1.15 to 1.50; p = .039). The hospital mortality rates for the two treatment groups were similar (protocol-directed 22.3% vs. physician-directed 23.6%; p = .779). Hospital cost savings for patients in the protocol-directed group were $42,960 compared with hospital costs for patients in the physician-directed group. CONCLUSION: Protocol-guided weaning of mechanical ventilation, as performed by nurses and respiratory therapists, is safe and led to extubation more rapidly than physician-directed weaning.

Aerosolized therapy for ventilator-assisted patients.

Although aerosols, especially bronchodilators, are routinely administered to ventilator-assisted patients, the practice lacks scientific proof that it improves the outcome of respiratory failure. Using sensitive instruments, investigators have found that aerosolized bronchodilators lead to improvement in airflow immediately following the treatment; however, no study to date has correlated short-term improvement in pulmonary function to a decreased incidence of barotrauma or reduced need for mechanical ventilation. Multiple variables interfere with optimum delivery of aerosols to ventilator-assisted patients, including the endotracheal tube, patient and ventilator breathing pattern, and the inefficiency of nebulizer systems. Recent evidence suggests that if aerosols are used to treat intubated patients, metered-dose inhalers are the devices of choice in terms of cost and efficacy.

Nutritional assessment of the patient in the intensive care unit.

Early identification and treatment of malnutrition in hospitalized patients remain important aspects of care, especially in critically ill patients. Thorough knowledge of a patient's nutritional history, physical assessment and clinical laboratory findings are critical in order to accurately determine the degree of malnutrition, if present, as well as metabolic energy needs. The nurse plays a vital role in gathering this valuable clinical information. Although there is no single test to determine malnutrition, the utilization of a complete nutritional assessment is the best tool to properly identify and treat malnutrition.

Pressure-controlled inverse-ratio ventilation.

The routine use of PCIRV in adult critical illness remains an area of considerable controversy and debate. This stems in large part from a lack of well-controlled studies demonstrating improved patient outcome over conventional mechanical ventilation techniques. Although it is unlikely that clinicians will stop using PCIRV until such data are available, nurses and other caregivers should exercise caution whenever this form of therapy is employed.

Nutrition and the use of metabolic assessment in the ventilator-dependent patient.

Nutritional support is an important aspect of care in hospitalized patients, especially those receiving mechanical ventilation. While nutritional assessments can help guide the clinician in determining appropriate caloric intake requirements and refeeding schedules, few tools exist to evaluate the consequences of over- or underfeeding. Metabolic assessment using indirect calorimetry is a new method of nutritional assessment for use at the bedside of the weaning patient. The data obtained from a metabolic assessment can be used to adjust formulas and total caloric intake as well as differentiate between dead space and elevated carbon dioxide production as reasons for persistent hypercarbia.

Alternate modes of mechanical ventilation.

As a result of technological progress and a better understanding of respiratory disease processes, new modes of mechanical ventilation for the critically ill patient have been developed. These new methods may offer specific advantages over traditional techniques by avoiding or reducing complications commonly associated with positive pressure ventilation. A thorough understanding of anticipated benefits and potential problems is carefully considered for each mode of mechanical ventilation. Several alternate approaches to ventilatory assistance are discussed. Clinical applications of nursing care are also discussed.

Exhaled gas analysis. Technical and clinical aspects of capnography and oxygen consumption.

Infrared absorption and mass spectrometry represent two common techniques used for measurement of end-tidal carbon dioxide concentration in expired air. Continuous capnographic monitoring may be useful in assessing changes in ventilation, pulmonary blood flow, and metabolism. Accuracy may be affected by the type of gas sampling technique used, as well as altered ventilation and perfusion matching in the lung. Oxygen uptake at the mouth may be measured by either an open- or closed-circuit technique. Calculated values of oxygen consumption obtained from pulmonary artery catheter data and blood gases correlate well with direct gas measurement. Accurate bedside determination requires a thorough knowledge of equipment and proper gas collection, especially at high inspired oxygen levels. This information may be useful in nutritional assessments, during mechanical ventilation, and in evaluation of therapeutic interventions aimed at optimizing peripheral oxygen delivery.

Determination of resting energy expenditure utilizing the thermodilution pulmonary artery catheter.

Accurate determination of the resting energy expenditure (REE) for patients in intensive care units has assumed increasing importance as the adverse effects of underfeeding or overfeeding have become clearer. As a result, indirect calorimetry is frequently used to determine the REE. This technique, however, is neither universally available nor inexpensive. Furthermore, it requires meticulous measurements of gas exchange and technical expertise. Because of this, we have developed a method to determine REE for those patients in intensive care units who have thermodilution pulmonary artery catheters in place. This method requires determining the oxygen consumption from data obtained from such a catheter. The REE is then calculated by multiplying the determined oxygen consumption by the caloric value for oxygen (4.86 kcal/L at a nonprotein respiratory quotient of 0.85). We made 20 simultaneous measurements of REE, comparing our method with indirect calorimetry in 19 patients. There was excellent agreement between both methods (r = 0.90; p less than 0.0001). Therefore, for those patients in intensive care units who require thermodilution pulmonary artery catheters, this method will allow accurate determination of REE and thus caloric requirements, without the need for indirect calorimetry using measurements of gas exchange.