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Biomedical subjects

A Sladen

Publications and source records attributed to A Sladen.

At least 19 recordsLinked to original sources
PubMed1988

Driving pressure and arterial carbon dioxide tension during high-frequency jet ventilation in postoperative patients.

To achieve normocarbia during conventional mechanical ventilation, ventilator settings are determined initially on the basis of body weight. The best ventilator settings for CO2 elimination during high-frequency jet ventilation (HFJV) have not been so clearly defined. A recent study has suggested that eucarbia will be obtained with HFJV when tidal volume (VT) per kg of body weight is kept within a narrow, well-defined range. In the same study, a "bench test" demonstrated that VT was directly proportional to the jet ventilator driving pressure (DP). The goal of our study was to confirm this recommended VT/kg to obtain eucarbia and to determine whether the relation observed between VT and DP in the laboratory was true clinically. We studied 14 patients admitted to the ICU for postoperative support. We determined a good correlation between DP and VT/kg (r = .811, p less than .001) for the group as a whole and a good inverse correlation between DP or VT/kg and PaCO2 for most individual patients; however, there was a poor inverse correlation between DP or VT/kg and PaCO2 for the group as a whole, due to wide patient-to-patient variation in the efficiency of jet ventilation. We conclude that there is no universal formula for setting jet ventilator DP or VT/kg to affect normocarbia in humans.

Body Weight↗
PubMed1987

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.

Evaluation Studies as Topic↗
PubMed1984

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 X 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.

Adolescent↗
PubMed1984

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 X m2, total systemic vascular resistance index (SVRI) 2846 and 2923 dyne X sec/cm5 X 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.

Aged↗
PubMed1983

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.

Adult↗
PubMed1977

Current concepts of the adult respiratory distress syndrome.

The adult respiratory distress syndrome (ARDS) is a sequel to pulmonary injury that may be direct, closed chest trauma or indirect, through air or vascular passages, aspiration, or fat embolization. An understanding of this syndrome is essential for the oral surgeon who not only manages severe maxillofacial injuries but is also a member of a trauma team that manages multisystem injuries. Emphasis on pathophysiologic pathways resulting in ARDS is presented with a discussion on oxygenation and ventilation abnormalities. Application of these guidelines will assist the oral surgeon in understanding the management of patients with this acute progressive syndrome.

Adrenal Cortex Hormones↗
PubMed1976

Methylprednisolone. Pharmacologic doses in shock lung syndrome.

Patients with shock lung syndrome were identified as those who developed acute respiratory failure after a profound episode of hypotension secondary to hemorrhagic, gram-negative, or endotoxic shock. In this study, each of the 10 patients with shock lung syndrome received methylprednisolone sodium succinate, 30 mg. per kilogram, intravenously every 6 hours for 48 hours. In addition, all patients were supported with mechanical ventilation, with or without positive end-expiratory pressure (PEEP). Arterial oxygenation improved markedly, and pulmonary edema resolved in all patients. Nine were discharged from the hospital and one died subsequently of disseminated intravascular coagulation. This study demonstrated a significant improvement in mortality rate with repeated pharmacologic doses of methylprednisolone compared to previously reported mortality rates of 60 to 90 per cent in patients with shock lung syndrome treated without repeated pharmacologic doses of steroid therapy.

Adult↗