High-frequency ventilation in the management of tracheal trauma.

Two cases of rupture of the trachea were treated by surgical repair. Intraoperative and postoperative ventilation was managed with high-frequency ventilation. This mode of ventilation afforded good intraoperative exposure and support as well as good postoperative ventilation despite pulmonary contusion without requiring inflation of the endotracheal tube cuff against tracheal suture lines. We recommend high-frequency ventilation in the management of tracheobronchial trauma intraoperatively and postoperatively, because it allows good ventilation despite pulmonary contusion without high positive airway pressures and without the necessity for inflation of the endotracheal tube cuff against a tracheal suture line.

Comparison of high-frequency lung ventilation with conventional mechanical lung ventilation. Prospective trial in patients who have undergone cardiac operations.

High-frequency lung ventilation was compared with conventional mechanical lung ventilation following elective cardiac operation. The results indicate that this high-frequency ventilator works as well as conventional mechanical ventilators and that it accomplishes the desired gas exchange at lower peak airway pressures. We conclude that routine use of high-frequency ventilation in the postoperative period is possible and that it may be indicated if lower peak airway pressures are desired.

Use of a computerized respiratory care record system to study utilization of IPPB therapy.

Increases in the utilization of respiratory therapy and the need to avoid its misuse have placed increasing management responsibilities on medical and technical supervisors of respiratory care services. To improve our managerial capabilities we designed a computerized respiratory care record system. Respiratory therapists use specially designed forms to record initial respiratory assessments and subsequent progress notes. A computer program allows secretaries to enter information from the forms into a data base. Another program tabulates information from the data base. As an example of the usefulness of this system we present a study of the utilization of intermittent positive-pressure breathing (IPPB) therapy in patients undergoing intrathoracic or upper abdominal surgery. Although all such patients were routinely educated preoperatively in the use of IPPB, chest physiotherapy, and incentive spirometry, the study revealed that only 14% of the patients received IPPB postoperatively, whereas more than 90% received chest physiotherapy and incentive spirometry. As a result of our findings we are saving time and money by discontinuing routine IPPB education for this population.

Bacterial contamination of arterial lines. A prospective study.

One hundred seventeen patients had indwelling arterial illness for hemodynamic monitoring and blood sampling. The duration of catheterization varied from 25 to 439 hours, during which time no components of the system were replaced. In contrast to other reports, our study showed no instance of contamination of transducer dome fluid when the continuous flush device was located just distal to the transducer. The sampling stopcock showed bacterial growth in 16.2% of patients. In the one case in which the arterial catheter tip, stopcock, and patient's blood showed the same organism, culture of the transducer fluid was negative. Our results suggest that elimination of a static inline fluid column and proper aseptic sampling technique limit risk to the patient of transmitted bacterial infection from the fluid in the system. Routine changes of components of the system are not indicated and a substantial cost saving can be achieved.

Anesthesia and the control of blood pressure in patients with spinal cord injury.

The medical records of 78 procedures performed on 50 spinal cord injured patients at risk for developing autonomic hyperreflexia were evaluated for blood pressure changes during anesthesia and surgery. Hypertension was arbitrarily defined as a systolic blood pressure of greater than 140 torr. The 78 procedures were divided into three groups: group A, 19 procedures in which the patient received topical anesthesia, sedation, or no anesthesia; group B, 13 procedures conducted under general anesthesia; and group C, 46 procedures carried out under spinal anesthesia. Hypertension occurred in 15 of 19 procedures (79%) in group A, in three of 13 procedures (23%) in group B, and in three of 46 procedures (7%) in group C. Group A differed significantly from group B (p = 0.011) and group C (p = 1.2 X 10(-8)). There was no significant difference between groups B and C (p = 0.114). Results indicate that patients at risk for autonomic hyperreflexia are protected from developing intraoperative hypertension by either general or spinal anesthesia.

The dynamic responses of liquid-filled catheter systems for direct measurements of blood pressure.

Direct measurement of blood pressure with a fluid-filled catheter and transducer is widely accepted in clinical practice. However, errors associated with the measurements are often not appreciated. The system frequently is unable to reproduce rapidly changing waveforms and overshoots to produce higher peak pressures. The most common causes of this phenomenon are trapped small air bubbles and long connecting tubing. To assess the inaccuracy in pressure measurements, we calculated the weighted sum of the percentage difference between reference and recorded amplitudes of sinusoidal waveforms for several catheters and connecting tubings. We found that when the connecting tubing was shorter than 3 feet long and no air bubbles were trapped readings were accurate. On the contrary, connecting tubings 7 feet long or longer, and/or air bubbles, were frequently associated with inaccurate results. For example, minimal air bubbles (0.25 ml) in a system exaggerated the systolic pressure measurement by 41 torr when simulated blood pressure was 150/50 torr.

A method of maintaining sterility of heated humidifiers in mechanical ventilator breathing circuits.

Using the standard MA-1 breathing circuit, the Cascade Heated Humidifier and tubing become rapidly contaminated with patient organisms. The rapidity with which this occurs seems to depend on the quantity and quality of patient secretions and dumping infected water from lazy loops into the Humidifier. Following modifications to the ventilator circuit which included: (1) closed system humidifier filling, (2) the addition of a small copper trap and drainage system to the inspired side of the breathing circuit, and (3) alteration of the heater, no contamination of the humidifier contents occurred for periods as long as 28 days. This trap was manufactured in our hospital using standard plumbing fixtures; a commercial model is available. This system is applicable to any volume ventilator using a heated reservoir humidifier.

An evaluation of the cuff characteristics and incidence of laryngeal complications using a new nasotracheal tube in prolonged intubations.

A series of 1,187 nasotracheal intubations, carried out from January 1973 to December, 1975, used a new tube. The design included a smooth tip, a cuff with a large area of contact, low pressure and a high residual volume, and a radiopaque line which is easily visible on chest X-ray. A secondary irrigating lumen opening distal to the cuff provides closed-system irrigation, measurement of airway pressures, and sampling of tracheal gases. In the 811 intubated nontracheostomized patients who survived, the overall incidence of significant laryngeal damage was 1%. In patients intubated in excess of 10 days the damage incidence was 10%, and we suggest that tracheostomy should be carried out at this time. No patients suffered from any known permanent laryngeal damage.

Pulmonary function in patients with multiple trauma and associated severe head injury.

1) Sodium and water balance and pulmonary function studies were obtained in five patients with multiple injuries, including pulmonary contusion, plus severe intracranial trauma. All patients received dexamethasone, 4-6 every 6 hours during the 72-hour study period after injury. 2) Results were compared with those from 14 previously reported patients without head injury; none had received corticosteroids. 3) Study patients with head injury achieved negative water balance and almost-zero sodium balance within 72 hours of injury be excreting a high-volume, low-sodium urine. Despite elevated alveolar-arterial oxygen gradients and low-normal pulmonary compliance initially, there was progressive improvement and no patient developed post-traumatic pulmonary insufficiency. 4) The data suggest that the "negative" effects of major intracranial trauma on the kidney, heart, and lung are cancelled by dexamethasone, or that corticosteroids protect pulmonary function in the patient with multiple injuries and prevent post-traumatic pulmonary insufficiency, perhaps through their effect on the kidney leading to rapid restoration of sodium and water balance.

Ineffectiveness of methylprednisolone in the treatment of pulmonary dysfunction after cardiopulmonary bypass.

Fifty consecutive adults undergoing elective cardiac surgery with cardiopulmonary bypass received a single dose of methylprednisolone (30 mg/kg) at the time of anesthesia. The results were compared with those in the immediately preceding fifty adult patients who underwent elective cardiac surgery and who did not receive corticosteroids. The age, sex, and weight of the patient, mortality, nature of the lesions treated surgically, bypass time, smoking history, physiologic evidence of preexisting lung disease, preoperative New York Heart Association class, preoperative left ventricular end diastolic pressure, incidence and duration of the postoperative low cardiac output syndrome, postoperative arrhythmias, operative and postoperative blood loss and postoperative hours of respiratory support, dynamic lung-thorax compliance, alveolar arterial oxygen gradient, fraction of wasted ventilation, and incidence of tracheostomy were tabulated and statistically contrasted. The two groups were comparable relative to all preoperative factors, except for a slightly higher end diastolic pressure in the patients who received steroids. Methylprednisolone given at the time of anesthesia was associated with a higher intraoperative blood loss, a higher incidence of low cardiac output syndrome, and an increased requirement for postoperative mechanical ventilation. As bypass time approached three hours, the proportion of patients requiring prolonged support in both groups became similar. It was concluded that pretreatment with methylprednisolone in massive doses had an overall adverse cardiopulmonary effect.