Showing papers in "Critical Care Medicine in 1978"

Pentobarbital therapy for intracranial hypertension in metabolic coma. Reye's syndrome.

Abstract: In severe Reye's syndrome, with nonspecific intensive supportive therapy, the mortality rate approaches 75%. In many instances, death is due to uncontrolled cerebral edema and elevated intracranial pressure. (ICP). Pentobarbital therapy, sufficient to maintain a blood barbiturate level between 2.5 mg% and 4.0 mg%, was used to control ICP in seven patients with metabolic coma complicated by intracranial hypertension (intracranial pressure greater than 30 mm Hg for 30 min). The nadir of their neurological function was characterized by no response to deep pain, absent or abnormal oculocephalic responses, bilaterally dilated, unreactive pupils, and markedly irregular or absent respirations. Before barbiturate administration hyperventilation, steroids, mannitol, and other supportive therapies commonly used in Reye's syndrome were begun. After institution of pentobarbital therapy, the daily mannitol dose required to maintain the intracranial pressure below 20 mm Hg was significantly reduced (p less than 0.001), from 3.7 +/- 0.3 to 0.5 +/- 0.2 g/kg/day. All the patients survived, and six have no obvious neurological sequelae. Pentobarbital is a useful adjunct for intracranial pressure control in advanced metabolic coma.

Terminology update: optimal PEEP.

Abstract: The term, optimal PEEP, requires redefinition in the light of new clinical data. With the onset of acute respiratory failure heralded by blood gas evidence of decreased oxygenation, PEEP is supplied in quantities sufficient to restore intrapulmonary shunt (Qsp/Qt) to a preselected goal of 15%. This is compatible with published criteria defining adequate blood gas exchange. Now rather than permitting reduction of cardiac output to be the end point of PEEP application, selective cardiovascular interventions to support preload, contractility, or afterload are made as appropriate so that cardiac function may be maintained until the preselected endpoint of shunt reduction of 15% can be made.

Long-term radial artery cannulation: effects on subsequent vessel function.

Abstract: Radial artery function was studied in 114 consecutive patients by arteriography, Doppler ultrasound flow detection, and physical examination following prolonged (1-10 days) percutaneous cannulation with a single type of 20-gauge catheter. Cannulations lasting 1-3 days produced 11% arterial occlusion, whereas those lasting 4-10 days induced 29% incidence of occlusion (p less than 0.05). In addition, a significantly higher incidence of cannula dysfunction (38% versus 18%, p less than 0.05) and thrombus formation (0-3+ scale) was also observed in the group cannulated 4-10 days as compared with the group of shorter duration. The risk of vascular complications arising from percutaneous radial artery cannulation with 20-gauge catheters increases markedly after 3 days.

Treatment of adult respiratory distress syndrome with diuretics, dialysis, and positive end-expiratory pressure.

Abstract: Twelve patients were treated prospectively for adult respiratory distress syndrome with diuresis and low levels (less than or equal to 20 mm Hg) of positive end-expiratory pressure. Eight patients responded to diuretics and two to dialysis by an increase in static compliance of the respiratory system, improvement in arterial oxygen tension and an increased urine output. Two patients did not respond with an improvement in these tests. Responses were transient and multiple doses were required to produce a sustained effect. Even with improvement of pulmonary function after treatment, the mortality was 67%, similar to that reported from other centers since 1975. Recently a new treatment protocol has been proposed that uses high positive end-expiratory pressure (greater than or equal to 20 mm Hg) early in the course of adult repiratory distress syndrome; mortality using this technique was 20%. The difference in survival may be more apparent than real since each center has a unique population of patients and time of initial therapeutic intervention. A randomized collaborative study comparing treatment protocols is needed.

Acute life-threatening ventilation-perfusion inequality: an indication for independent lung ventilation.

Abstract: Although reports of independent lung ventilation are found in the literature more frequently, firm criteria for its use have not yet been established. It is probable that major ventilation-perfusion inequality, especially in cases in which the blood flow is primarily diverted to the less ventilated lung, could sometimes be corrected by this technique. The present report deals with such a case and describes the angiographic studies which convinced us that differential ventilation was necessary. By this means we were able to provide successful treatment for patients who had developed preterminal hypoxemia.

The effect of furosemide on the pulmonary transvascular fluid filtration rate

Abstract: Considerable controversy exists over the use of furosemide for the prevention of treatment of post traumatic respiratory insufficiency. The conflict revolves around the use of diuretic in a patient with this condition. There is some evidence that a nondiuretic effect of furosemide may be responsible for the reported improvement in lung function. We studied the response to furosemide of the pulmonary microvascular fluid filtration rate reflected in lung lymph flow (Qlym) in the normal lung. Using the unanesthetized sheep lung lymph preparation of Staub, we found a 30% decrease in Qlym after 80 mg furosemide. However, the majority of the decrease occurred within 15 min after injection when diuresis was just beginning. This response appeared to be due to a large decrease in pulmonary venous resistance, decreasing hydrostatic pressure. Protein flow (Qlym x lymph protein content) remained constant. Pulmonary artery pressure remained constant with left atrial pressure decreasing slightly. We have demonstrated that in the normal lung, furosemide significantly decreases the fluid filtration rate by a nondiuretic effect. Further studies of this response should help resolve the controversy over the indications for diuresis and center more attention on the actual mechanism of action of furosemide.

Cardiorespiratory and metabolic effects of profound hypothermia.

Abstract: At operation the body temperature of mechanically ventilated infants was initially decreased to 25--22 degrees C with surface cooling and further lowered to 16 degrees C by total body perfusion. During circulatory arrest, averaging 40 min, repair of complex intracardiac deformities was carried out. Rewarming to 36 degrees C was achieved by 35--65 min of total body perfusion. Of 29 infants, 23 under 10 kg survived their correction; normothermic ventilation without added CO2 was given throughout the cooling period. The following measurements were made: gas exchange, lung mechanics, heart rate, arterial pressure, right atrial pressure, cardiac output (Qt), ECG, core and nasopharyngeal temperature, as well as biochemical determinations. During surface cooling O2 consumption (VO2), CO2 production (VCO2), endtidal CO2 (PETCO2) and PaCO2 decreased proportionally and linearly with body temperature. Inspiratory resistance, total compliance, physiological dead space (VD/VT), and the single breath CO2 curve did not reveal disturbed lung function. Mean arterial pressure was 98, 90, and 70 mm Hg and heart rate was 141, 107, and 76 beat/min, at temperature 35, 30, and 25 degrees C, respectively. Cardiac index was 2.2 +/- 0.2 liter/min/m2 (mean +/- SEM, n = 25) 2 hours after surgery. Arterial lactate reached peak values of 4.1 +/- 0.3 mM/liter (n = 17), during rewarming but returned to normal. Respiratory alkalosis caused by hyperventilation during cooling caused no apparent harm. No neurological damage was observed. It is concluded that surface cooling performed with normothermic ventilation under guidance of core temperature, VO2, PETCO2, and VCO2, is a safe method.

Reduced oxygen consumption in catabolic states with mechanical ventilation.

Abstract: Most critically ill patients have a high catabolic rate to which sepsis, restlessness, and the hormonal stress response may be contributing factors. This has been confirmed by measurement of oxygen consumption. (Vo2) as a reflection of energy expenditure. While acutely ill patients may adapt to this situation, one of their adaptative mechanisms is to increase their minute ventilation. Increased minute ventilation increases the work of breathing and the oxygen cost of respiratory work. The higher the minute ventilation, the higher the percentage of oxygen consumed for respiratory work. In order to evaluate the magnitude of these factors, 20 acutely ill patients (severe burns, multiple injuries, and comatose states) were studied by measurements of Vo2 during mechanical ventilation and after disconnection from the ventilator for short periods of time; i.e., 20 min. Paired tests, on and off ventilator, were performed successively three to five times on each patient ventilated for various reasons, but not those in respiratory distress. The tests were mainly performed during the period of weaning from mechanical ventilation. A reproducible increase in Vo2 was observed in most patients when they were disconnected from mechanical ventilation and allowed to breathe spontaneously. The observed reduction of Vo2 with mechanical ventilation was interpreted as a direct result of mechanical ventilation. The possibility of extending the indications for mechanical ventilation in hypercatabolic state patients without acute respiratory failure is discussed.

Acquired right-to-left intracardiac shunts and severe hypoxemia.

Abstract: Critically ill hypoxemic patients without significant radiological changes on the chest x-ray present a diagnostic and therapeutic problem. Three patients with patent foramen ovale and a patient with a spontaneously closed congenital ventricular septal defect which reopened due to ischemic changes in the ventricular septum are presented. In reviewing the literature, we could not find this type of presentation. Their hypoxemia was associated with right-to-left intracardiac shunts demonstrated by dye dilution cardiac output curves. Because of the risk of systemic embolism associated with a right-to-left intracardiac shunt, air bubbles and particulate material in the intravenous infusion should be avoided. Use of anticoagulants may be beneficial. High inspired oxygen concentration may not correct the associated hypoxemia. The detection of these shunts is easily done at the bedside.

Optimal flow pattern for mechanical ventilation of the lungs. 2. The effect of a sine versus square wave flow pattern with and without an end-inspiratory pause on patients.

Abstract: In four series of patients, the efficiency of ventilation of a sine wave without an end-inspiratory pause was compared to a square wave without a pause, a sine wave with a pause to a square wave with a pause, a sine wave to a sine wave with a pause, and a sine wave with a long pause to one with a short pause. The primary mode of evaluation was through simultaneous airway and arterial argon washout curves. Additional cardiopulmonary measurements were made. Results indicate: (1) a statistically significant improvement in ventilation with a sine wave with a pause; (2) a statistically significant improvement with the longer pause as compared to the short pause.

The effects of expiratory positive airway pressure on functional residual capacity in normal subjects.

Abstract: Functional residual capacity (FRC) was determined by constant volume, whole body plethysmography in seven normal subjects under resting conditions and following the addition of increasing levels of expiratory positive airway pressure (EPAP). There was a significant increase in FRC in six of the seven subjects studied. Grouped data showed a progressive increase in FRC with increasing EPAP (p less than 0.01). The highest level of EPAP (15 cm H2O) was associated with a 20% increase in FRC. We have been able to confirm that EPAP provides a simple and effective method of increasing FRC which could be applied to the treatment of conditions characterized by temporary and reversible reduction in lung volume.

Alveolar rupture as an independent predictor of bronchopulmonary dysplasia.

Abstract: The chest radiographs and charts of 99 surviving neonates treated with positive pressure ventilation for respiratory distress syndrome were reviewed. Forty infants developed alveolar rupture during mechanical ventilation. Of these, 27 (67.5%) developed bronchopulmonary dysplasia (BPD). Only 3 (5.4%) of the remaining 59 infants developed BPD. The relative odds of developing BPD if alveolar rupture occurred increased by a factor of 39 (p < 0.001). Significant associations between BPD and the duration of ventilation with high peak inspiratory pressures (IP) ≥ 40 cm H2O, low peak IP ≤ 39 cm H2O, continuous distending pressure ≥ 5 cm H2O and fractional inspired oxygen concentration (Fio2) ≥ 0.6 were examined. Since these ventilatory parameters had a significant association (p ≤ 0.02) with both BPD and alveolar rupture, an attempt was made to identify the independent contributions of these factors to the development of BPD by a stepwise discriminant analysis. Controlling for the most significant associations, FIO2 ≥ 0.6 and peak IP ≤ 39 cm H2O, subsequent analysis showed no added discriminant power of predicting BPD in the duration of exposure to high peak IP ≥ 40 cm H2O and continuous distending pressure ≥ 5 cm H2O. Alveolar rupture remained overwhelmingly significant (p < 0.001), but it did not account entirely for the development of BPD. Duration of exposure to peak IP ≤ 39 cm H2O and FIO2 ≥ 0.6 remained significant. These results suggest that pulmonary barotrauma as reflected by the occurrence of alveolar rupture during positive pressure ventilation is intimately related with the subsequent development of BPD.

Effects of the mask and mouthpiece plus noseclip on spontaneous breathing pattern.

Abstract: Studies of breathing patterns that use a mask (M) or mouthpiece plus noseclip (MP + NC) may contain artifacts due to the stimuli of the apparatus used. A canopy-spirometry-computer system was used to analyze respiratory patterns in a noninvasive manner. Changes in respiration induced by the application of M or MP + NC were analyzed. Twenty-two normal subjects and five critically ill patients were studied in (1) canopy alone, (2) canopy with M and (3) canopy with a MP + NC (in normal subjects only). An algorithm quantified each breath and determined tidal volume (VT), frequency (f), minute ventilation (V), O2 consumption (VO2), CO2 production (Vco2), sigh frequency (SF), ventilatory equivalent (VEco2 defined as V/Vco2), and tidal volume distribution (VTD) VTD that reflects the tendency to breathe in a relatively narrow range of tidal volumes and is quantified as VTD10, VTD20 (% breaths within ± 10% and ± 20% of mean VT). The M increased VT, V, VEco2 (presumbly secondary to its increased dead space) VTD10 and VTD20. MP + NC increased VT, V and decreased VTD10 and VTD20. Neither device affected SF. The M produced similar changes in the resting ventilation of both the patients and normal subjects. Our previous studies have shown that ill patients breathe at relatively fixed VT, i.e., high VTD10 and VTD20. Use of a M or MP + NC obscured this phenomenon and altered VT, V, and VEco2

The relationship of bronchopulmonary dysplasia to the occurrence of alveolar rupture during positive pressure ventilation.

Abstract: The effect of altered mechanical ventilation on the incidence of alveolar rupture and bronchopulmonary dysplasia (BPD) was reviewed in infants who had neonatal respiratory distress syndrome (RDS) (N = 99). From 1971 to 1974 we attempted to minimize pulmonary oxygen exposure. Accordingly, during the resolution of respiratory distress syndrome, the ventilator pressures were not reduced until the FIO2 had been lowered to 0.4 (n = 61). In 1974 to 1975 earlier reduction of pressure was instituted as the FIO2 was lowered to 0.6 or less (N = 38). Birth weight and gestational age were comparable in the two groups. With earlier reduction of ventilator pressures, there was a significant decrease in the duration of exposure to peak inspiratory pressures greater than or equal to 40 cm H2O (p is less than 0.004) and greater than or equal to 50 cm H2O (p is less than 0.002). The incidence of alveolar rupture during postive pressure ventilation fell from 51 to 24% (p is less than 0.015) and bronchopulmonary dysplasia from 41 to 13% (p is less than 0.003). In addition, there was a decrease in the duration of mechanical ventilation (p is less than 0.02) and exposure to an FIO2 is greater than or equal to 0.6 (p = 0.07). The results confirm the intimate relationship of pulmonary barotrauma, as reflected by the occurrence of alveolar rupture during positive pressure inflation of the lungs, to the subsequent development of bronchopulmonary dysplasia and that prevention of the former is associated with a concomitant fall in incidence of the latter.

Method for continuously measured oxygen consumption and cardiac output for use in critically ill patients.

Abstract: A method for continous measurements of oxygen consumption (VO2) and cardiac output is described. This relatively inexpensive system was found to be practical for monitoring critically ill patients over the past 5 years. Clinical studies illustrating its usefulness are presented.

Long-term infusion of sodium thiopental: hemodynamic and respiratory effects.

Abstract: To establish the possible advantages of ultrashort acting barbiturates administered in continuous infusion as the only sedative agent for mechanically ventilated patients, sodium thiopental was given to 30 subjects for periods ranging from 2--14 days. Plasma levels were maintained at approximately 15 microgram/ml, using both laboratory determinations and clinical judgment. This technique proved effective for patients requiring either controlled ventilation or intermittent mandatory ventilation. None of the hemodynamic and respiratory variables studied was significantly altered during the infusion, with the exception of decreased heart rates. In view of these results, the technique is considered both expedient and safe for prolonged sedation of patients requiring ventilatory support.

A flowmeter for respiratory monitoring.

Abstract: A variable-orifice pneumotachograph is described. It has a resistance that is relatively constant over a flow range from 0.1 to 2.5 liter/sec so it puts out a differential pressure signal that is directly proportional to flow. It is specifically designed for monitoring respirator patients and sacrifices some of the accuracy of a laminar flow (Fleisch) type device to gain greatly improved immunity to artefacts caused by airway water.

Artifacts in the measurement of pulmonary artery wedge pressure.

Abstract: Pulmonary artery wedge pressure (PAWP) will only reflect left atrial pressure (LAP) if continuity of fluid exists from the catheter tip to the left atrium. Either increased airway pressure or decreased hydrostatic pressure may lead to discontinuity of the fluid column and misinterpretation of PAWP. Simultaneous measurements of PAWP and LAP were made in 19 anesthetized dogs. Placement of the pulmonary artery wedge catheter above the left atrium (West Zone I) in combination with the incremental addition of 5 cm H2O of PEEP caused a 5 mm Hg gradient between PAWP and LAP in the normovolemic animal. Augmenting PEEP further or hypovolemia (i.e., decrease in LAP) increased the gradient. Hypervolemia (increase in LAP) diminished the gradient. Fluid continuity between the PAW catheter and LA is a prerequisite for monitoring LAP with the Swan-Ganz catheter. Increases in PEEP, placement of the catheter above the left atrium and hypovolemia may occlude the fluid column and cause artifacts in the PAWP obtained.

Immediate and long-term outcome of infants less than 1000 grams.

Abstract: In order to assess the immediate and long-term outcome of very low birth weight infants, a retrospective analysis of clinical and biochemical parameters of 100 consecutive newborns with birth weights less than 1000 g was carried out. Overall neonatal mortality for this group was 69%. For infants between 751 to 1000 g, the mortality rate was 52%. Of the 23 infants who were discharged, neurodevelopmental assessment was performed in 16. Twelve of the 16 were neurologically normal. The data indicate a favorable prognosis for infants with birth weight less than 1000 g.

Fiberoptic bronchoscopic balloon occlusion and reexpansion of refractory unilateral atelectasis.

Abstract: A new method using the flexible fiberoptic bronchoscope is described for the reexpansion of refractory unilateral lung or lobar atelectasis The technique is well adapted for the critically ill ICU patient

Psychological reactions to acute medical illness and critical care

Abstract: The psychological stresses evoked by acute critical illness and intensive care in both patient and physician are examined and certain approaches proposed which, in our experience, can alleviate these stresses. Admittedly, these psychological concepts may appear inconsequential at first glance. We have found, however, that such intervention may facilitate the physician's efforts to provide appropriate care for his critically ill patients, including those who must die, without experiencing the psychological reactions--the guilt, shame, anguish, and despair--these patients typically arouse.

The risk of positive cultures for Candida in the critically ill patient.

Abstract: It is frequently stated that a positive fungal culture is of little clinical significance unless the culture is obtained on repetitive blood specimens. We analyzed the mortality associated with a positive culture for Candida species in ICU patients from several locations over a 3-month period. Criteria for inclusion in this study were: (1) residence in the ICU for at least 4 days, (2) no GI tract alimentation during this period, and (3) administration of at least one antibiotic during this period. Forty-four patients fit these criteria; 23 had positive Candida cultures from at least one site and 12 (52%) died. Four of 21 patients (19%) who did not grow Candida died. Cultures of urine and sputum were most likely to be positive. Positive cultures from the urine, sputum, or wound were associated with at least a 50% mortality. This suggests that routine sputum and urine cultures may be of substantial clinical therapeutic and prognostic significance. Two patients had positive blood cultures and both died. No single class of antibiotics, surgical complications or underlying disease predisposed to these results. It is concluded that the presence of a single positive culture for Candida from any site in the critically ill surgical patient kept without GI alimentation and on any antibiotic is a grave prognostic sign which requires further attention.

Multiple organ failure after near-hanging. A case report.

Abstract: Near-hanging and strangulation injuries can result in multiorgan failure. A 13-year-old male sustained an ischemic anoxic cerebral injury that was followed by an encephalopathy lasting approximately 30 hours and pulmonary edema lasting more than 48 hours. The patient was treated with continuous positive pressure ventilation followed by spontaneous breathing with continuous positive airway pressure by a mask; shock was reversed. The loss of cardiovascular competency and pulmonary insufficiency are problems frequently encountered in the patient who has sustained an hypoxic insult. Cerebral injury can result from hypoxemia related to tracheal compression, aspiration, and pulmonary edema; cerebral vascular engorgement secondary to venous compression; and ischemic anoxia related to arterial compression. Cerebral changes continue after circulatory and pulmonary competence has been restored. Multiorgan monitoring and control including intracranial pressure monitoring may be required to guide therapy. Respiratory distress syndrome may develop secondary to multiple factors including autonomic reflexes triggered by cerebral hypoxia and edema. Language: en