Arnold Sladen

PEEP vs. ZEEP in the treatment of flail chest injuries.

Nine consecutive patients with flail chest injuries were treated with mechanical ventilation and positive end-expiratory pressure (PEEP). Twenty-eight studies were performed, beginning on the day of admission. Blood and gas samples were evaluated during ZEEP and again after 30 min of PEEP of 10 or 15 cm H2O. In 24 studies, the Pao2 increased with PEEP. The lower the Pao2 at ZEEP, the greater the improvement with PEEP. The &OV0312;D/&OV0312;T ratio showed no significant change with either PEEP or ZEEP. Seven studies also included (a-v)Do2 and &OV0312;S/&OV0312;T. The &OV0312;S/&OV0312;T was reduced following the application of PEEP. A reduced Pao2 was associated with an in-crease in (a-v)Do2 in four of these studies. Improvement in oxygenation in patients treated with mechanical ventilation and PEEP is attributed to a change in FRC toward the normal. Etiologic factors causing a reduction in FRC in patients with flail chest injuries are discussed. Use of this technique improved oxygenation and allowed the Fio2 to be reduced in the majority of these patients.

High-frequency jet ventilation in the postoperative period: a review of 100 patients.

One hundred patients were ventilated with high-frequency jet ventilation (HFJV) during the initial 24-h postoperative period in the surgical and neurosurgical ICUs. Eighty-three were successfully weaned, 2 could not be ventilated adequately with HFJV, and 15 with criteria of acute respiratory failure received HFJV for up to 21 days. A HFJV delivery system consisted of jetting and entrainment systems, both with their own humidification designs. An initial mode of HFJV using 35 psi, jet rate 100 cycle/min and inspiratory time 30% provided a mean Paco2 of 34 torr in 38 patients studied. A comparison of HFJV without and with a positive end-expiratory pressure (PEEP) of 10 cm H2O indicated a decrease in mean Qsp/Qt from 17% to 13% with decrease in cardiac index (CI) from 3.39 to 2.81 L/min·m2; this effect is similar to PEEP applied to a conventional ventilator. Weaning proved to be simple and comfortable for the patient. In the light of our experience, we believe that HFJV is both feasible and practical for the postoperative patient and should be introduced into routine clinical use.

High-frequency jet ventilation versus intermittent positive-pressure ventilation.

Airway pressures and cardiorespiratory variables were compared for conventional ventilation (CV) and high-frequency jet ventilation (HFJV), at a similar fraction of inspired O2 (Fio2), positive end-expiratory pressure (PEEP) and Paco2 in 11 ICU patients. For CV and HFJV, respectively, peak (PAP) and mean airway pressures (Paw) were 15.4 and 9.1 mm Hg and 4.4 and 5 mm Hg. Cardiac index (CI) was 2.54 and 2.60 L/min·m2, total systemic vascular resistance index (SVRI) 2846 and 2923 dynesec/cm5·m2, Pao2 207 and 149 torr, and Qsp/Qt 7% and 11%. HFJV decreased significantly PAP and was less likely to produce pulmonary barotrauma. Cardiac indices were not different, indicating that this variable may be affected by Paw. HFJV neither increased nor decreased CI at similar PEEP and Paco2 as compared to CV. The decrease in Pao2 and increase in Qsp/Qt may be due to small inspired gas volumes potentiating microatelectasis. On the basis of this study, we recommend initiating HFJV at Fio2 of 0.9 and PEEP of 5 cm H2O, and monitoring both PAP and Paw.

Synchronous versus nonsynchronous high-frequency jet ventilation: effects on cardiorespiratory variables and airway pressures in postoperative patients

In order to compare the differences of high-frequency jet ventilation (HFJV) synchronized with the cardiac cycle (sync) to that nonsynchronized with the cardiac cycle (async), ten stable postoperative ICU patients, without heart failure, in sinus rhythm were ventilated randomly in either mode. The async mode was HFJV at 100 cycle/min, while the sync mode was HFJV triggered by the R-wave of the ECG tracing. The heart rate ranged between 64 and 127 beat/min. Synchronization was studied at one of two periods, sync 0 and sync 60. Sync 0 consisted of inspiration triggered by the R-wave, with jet ventilation occurring early in systole; sync 60 represented a 60% delay of the time between the succeeding R-waves, with jet ventilation occurring in mid-diastole. There was no significant difference in the cardiorespiratory data when async was compared to either sync 0 or sync 60. Therefore, in these patients without heart failure, the selection of async vs. either sync mode appeared to have neither adverse nor beneficial hemodynamic effects.

Renal function and renin secretion during high frequency jet ventilation at varying levels of airway pressure.

The effect of positive end-expiratory pressure (PEEP) on plasma renin activity (PRA), renal function, and cardiovascular (CV) hemodynamics during high frequency jet ventilation (HFJV) was observed in 7 patients. The addition of PEEP during HFJV increased PRA while decreasing stroke index (SI) and cardiac index (CI). These changes were associated with decreased urinary flow, creatinine clearance, and fractional excretion of sodium. In contrast, HFJV at zero end-expiratory pressure (ZEEP) maintained normal PRA, renal function, and CV hemodynamics. The authors conclude that the alteration of renal function during HFJV is a function of airway pressure rather than the effects of the ventilatory frequency. The deterioration of renal function may have been due to changes in PRA or CV dynamics.

Effects of induced total-body hyperthermia on phosphorus metabolism in humans

The effects of total-body hyperthermia on phosphorus homeostasis are controversial. To evaluate the problem, 10 clearance studies were performed in seven patients undergoing total-body hyperthermia as an adjunct to the treatment of solid malignant tumors. Total-body hyperthermia was associated with significant reduction in plasma phosphorus concentration from a baseline value of 3.51 +/- 0.18 to 0.6 +/- 0.1 mg/dl (p less than 0.001), returning to baseline following cessation of total-body hyperthermia. The clearance of phosphorus increased from 15.2 +/- 2.5 to 26.1 +/- 3.1 ml per minute (p less than 0.01), and the fractional excretion of phosphorus increased from 11.37 +/- 2.2 to 47.68 +/- 9.7 percent (p less than 0.01). The reduction in plasma phosphorus during total-body hyperthermia was also associated with a significant reduction in the renal threshold phosphorus concentration from 3.17 +/- 0.16 to 0.38 +/- 0.08 (p less than 0.001). The changes in phosphorus homeostasis during total-body hyperthermia were independent of changes in circulating parathyroid hormone level, urinary cyclic AMP excretion, and arterial carbon dioxide tension.

High-frequency jet ventilation in weaning the ventilator-dependent patient.

Nine ventilator-dependent patients were successfully weaned from mechanical ventilatory support by high-frequency jet ventilation. All patients had been on ventilatory support for at least 2 wk, and had not responded to attempts at weaning by intermittent mandatory ventilation.

High-frequency jet ventilation and tracheobronchial suctioning.

Oxygenation and ventilation were assessed in 15 post-operative patients before, immediately after, and 3 min after 15 sec of tracheobronchial suctioning in the presence or in the absence of high-frequency jet ventilation (HFJV). When HFJV was continued during suctioning, the mean Pao2 decrease was only 15 ± 9 torr, compared to a 90 ± 16 torr decrease when HFJV was discontinued. This difference demonstrates that continuation of HFJV during tracheobronchial suctioning prevents a decrease in Pao2.

High Frequency Jet Ventilation and Conventional Ventilation: A Comparison of Cardiorespiratory Parameters

High frequency jet ventilation frequently is suitable as an alternative to conventional ventilation when ventilatory support is indicated.

Cardiopulmonary Resuscitation (CPR) Basic and Advanced Life Support (BLS, ALS) Self-Training Systems (STS) for Paramedical and Medical Personnel

Resuscitation and acute respiratory care must be taught to all personnel involved in the management of everyday emergencies and mass casualties. Personnel range from the lay public to physician specialists. In deciding who should be taught what and how one must consider the limitations of learning ability of trainees and of resources. Mouth-to-mouth ventilation can be learned by laymen merely from viewing pictures, but better with manikin practice to perfection. CPR steps A-B-C can be effectively taught to non-physicians including laymen with instructor-coached manikin practice to perfection. but also with self-practice coached by audiotape, and to some extent even by frequent film viewing only without manikin practice. In 1972, A. Laerdal invented a CPR steps A-B-C self-training system consisting of a recording manikin, flipcharts and the coaching audiotape. We added a demonstration film to be shown before manikin practice.