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Biomedical subjects

A Perel

Publications and source records attributed to A Perel.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Hemato-oncology patients in acute respiratory failure in the ICU].

Hemato-oncology patients needing mechanical ventilation for acute respiratory failure (ARF) have an extremely poor prognosis, with a mortality of more than 90%. Over an 18 month-period 17 such patients were admitted to our ICU. Diagnoses included leukemia (11 cases), lymphoma (1), and status post bone marrow transplantation for leukemia, lymphoma or breast cancer (5). Of 8 whose ARF was associated with septic complications due to neutropenia following chemotherapy, 6 survived. Of 9 who developed ARF due to toxic damage to vital organs following high-dose chemotherapy, 2 survived. Those who develop ARF during chemotherapy are expected to have an increase in granulocyte count within days, and have a surprisingly good prognosis. They should be admitted to the ICU and treated aggressively. Those who develop sepsis due their primary disease and whose general condition contraindicates chemotherapy, have an extremely grave prognosis and admission to the ICU may not be warranted.

Adult↗
PubMed1997

The Israeli Diagnostic Center for Malignant Hyperthermia: 7-years' accumulated experience.

Malignant hyperthermia (MH), a rare pharmacogenetic trait, can be lethal when susceptible individuals are exposed to triggering agents during general anesthesia. We present our experience with the caffeine-halothane in vitro contracture test (IVCT) for the diagnosis of malignant hyperthermia susceptibility. Out of 75 patients that were referred for consultation to the MH diagnostic center over a period of 7 years, we performed muscle biopsies and IVCT in 21 patients. A total of 6 patients were found to be MH-positive. Appropriate recommendations for future anesthetic management, and additionally, for testing the immediate family were made following a positive diagnosis. Improved familiarity with the syndrome of MH, and performance of IVCT when family or clinical history suggest malignant hyperthermia susceptibility, are imperative measures to prevent the potential fatality associated with this syndrome.

Academies and Institutes↗
PubMed1996

Pressure support ventilation.

The field of ventilatory support has changed dramatically with the introduction of improvements in technology and new ventilatory modes. The most recent ventilators are characterized by microprocessor technology, making the interaction between patient and ventilator more sophisticated than ever before. This technology has enabled the development of pressure support ventilation, which has gained extensive popularity during the past 10 years. Pressure support ventilation is different from controlled mechanical ventilation or intermittent mandatory ventilation; pressure support ventilation is characterized by a unique combination of simultaneous spontaneous and mechanical breathing, so that the ventilatory and flow rates and tidal volume depend on the patient's breathing pattern and the set level of pressure support. Pressure support ventilation can be used as a stand-alone ventilatory support mode and alternative to volume-controlled ventilation, and it can be used in weaning patients from mechanical ventilation.

Humans↗
PubMed1996

Positive end-expiratory pressure-induced hemodynamic changes are reflected in the arterial pressure waveform.

OBJECTIVE: To examine whether the hemodynamic changes due to mechanical ventilation with positive end-expiratory pressure (PEEP) can be assessed by the respiratory-induced variations in the arterial pressure waveform during normovolemia and experimental acute ventricular failure. DESIGN: Prospective, controlled experimental study. SETTING: Institutional experimental laboratory. SUBJECTS: Adult mongrel dogs. INTERVENTIONS: Experimental acute ventricular failure was induced by the infusion of pentobarbital (a cardiodepressant) and methoxamine (a vasoconstrictor), combined with volume loading. Both the control and acute ventricular failure groups were subjected to ventilation with incremental levels of PEEP up to 20 cm H2O. MEASUREMENTS AND MAIN RESULTS: Cardiac function was evaluated by cardiac output and left and right ventricular change in pressure over time (dP/dt) measurements. Arterial pressure waveform analysis was performed by measuring the systolic pressure variation, which is the difference between the maximal and minimal systolic blood pressure values during one mechanical breath. The components of the systolic pressure variation, namely, dUp and dDown, which are the increase and decrease in the systolic pressure during the mechanical breath relative to the systolic pressure during apnea, were also measured at each PEEP level. PEEP caused significant reduction of cardiac output in normovolemic dogs, and was associated with significant increases in systolic pressure variation and dDown. Acute ventricular failure decreased the variations in the systolic pressure and caused the dDown component to disappear. The application of PEEP did not affect cardiac output in dogs with acute ventricular failure, nor did it change systolic pressure variation and the dDown. CONCLUSIONS: Analysis of arterial pressure waveforms during mechanical ventilation reflected the decrease in cardiac output in dogs with normal cardiac function subjected to incremental PEEP. In dogs with acute ventricular failure in which PEEP did not affect cardiac output, the systolic pressure variation was similarly unaffected by PEEP. In the absence of cardiac output measurement during mechanical ventilation with PEEP, the analysis of the respiratory variations in the arterial pressure waveform may be useful in assessing changes in cardiac output.

Animals↗
PubMed1995

Determinants of systolic pressure variation in patients ventilated after vascular surgery.

OBJECTIVE: To discover the predominant determinant of systolic pressure variation during positive-pressure ventilation in mechanically ventilated patients after a vascular surgical procedure. DESIGN: Case control study. SETTING: Postanesthesia care unit at a university hospital. PARTICIPANTS: Eleven patients who were sedated during mechanical ventilation after abdominal aortic surgery. INTERVENTIONS: Radial arterial pressure and airway pressure were simultaneously recorded. The systolic pressure variation was measured as the mean difference between the maximal and minimal systolic pressure values during five consecutive mechanical breaths. The delta down was measured as the difference between the systolic blood pressure during apnea and the minimal values of the systolic pressure after one mechanical breath. The velocity time integral, which is closely related to stroke volume, was measured throughout the systolic pressure measurements. MEASUREMENTS AND MAIN RESULTS: Positive correlation was found between changes in velocity time integral and the magnitude of both systolic pressure variation (r = 0.73) and delta down (r = 0.80). Volume loading did not significantly modify systolic blood pressure. However, it did not significantly decrease systolic pressure variation and delta down. The corresponding changes in velocity time integral provoked by mechanical ventilation decreased significantly as well. CONCLUSIONS: The decrease in systolic pressure provoked by positive-pressure inspiration reflects simultaneous decreases in stroke volume. This suggests that a decrease in left ventricular filling, associated with positive-pressure inspiration, is responsible for systolic pressure variation. This finding confirms the interest in considering systolic pressure variation to provide reliable information about the responsiveness of the heart to preload variations.

Aged↗
PubMed1994

A comparison of systolic blood pressure variations and echocardiographic estimates of end-diastolic left ventricular size in patients after aortic surgery.

As suggested by experimental studies, systolic pressure variation (SPV), the difference between maximum and minimum values of systolic blood pressure after a single positive pressure breath, may be a fair indicator of left ventricular preload. SPV was quantified in 21 patients who had undergone abdominal aortic surgery and were sedated under mechanical ventilation. The aim of the study was to assess the ability of this parameter to qualitatively estimate left ventricular preload measured using transesophageal echocardiography. All patients had preoperative radionuclide ejection fraction > 45%. Postoperative mechanical ventilatory patterns were the same for all patients: tidal volume = 10 mL/kg; respiratory frequency = 12-14 breaths/min; and zero end-expiratory pressure mode. Left ventricular dimensions at end-diastole correlated well with the magnitude of both SPV (r = 0.80) and its delta down (dDown) component (i.e., the degree by which systolic pressure decreases with each mechanical breath) (r = 0.83). Once the first measurement was completed, volume loading with two increments of 250 mL of human albumin 5% was performed in all but three patients. Each volume loading step caused a significant increase in the end-diastolic area (EDa) index (7.0 +/- 1.6 to 8.5 +/- 1.6 cm2/m2) and cardiac index (CI) (3.1 +/- 0.9 to 4.1 +/- 0.9 L.min-1 x m-2) and a concomitant significant decrease in the SPV (8.6 +/- 4.5 to 6.1 +/- 3.7 mm Hg) and its dDown component (5.9 +/- 4.1 to 2.9 +/- 2 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Use of flumazenil for intraoperative arousal during spine fusion.

The intraoperative arousal test is used to detect potential damage to the spinal cord during spine fusion. We determined whether a continuous midazolam infusion, the effects of which are antagonized by flumazenil when the arousal test is needed, is associated with good control of the timing of arousal and with no adverse reactions. In a randomized study of 20 patients (10 in each group), we compared arousal with flumazenil during midazolam-narcotic anesthesia with an arousal test done during halothane-nitrous oxide anesthesia, both under conditions of controlled hypotension. Motor responses to verbal command were obtained 39.1 +/- 36.0 s (mean +/- SD) after the injection of flumazenil in eight patients. Two patients form this group awoke spontaneously 6 and 8 min after terminating the administration of nitrous oxide and midazolam but remained sedated up to the time of the test itself. In the halothane group, arousal occurred 26 +/- 8.3 min after halothane administration was terminated and 10.1 +/- 3.3 min after nitrous oxide was stopped. Two of the patients in this group moved, owing to early arousal 5 and 8 min before the scheduled time and needed reinstatement of anesthesia. In four patients in the halothane group, we had to wait 3-11 min after the scheduled time before satisfactory arousal was achieved. One of the patients in the halothane group showed a motor deficit of the lower limbs during the wake-up test that disappeared after decreasing the spine correction. There were no adverse reactions except for occasional shivering in the recovery period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[In vitro diagnosis of malignant hyperpyrexia syndrome].

Malignant hyperthermia syndrome (MHS) is rare, inherited, and triggered by volatile anesthetics and depolarizing muscle relaxants. While potentially fatal, if recognized and treated early recovery is usual. However, the condition is often not recognized until an extreme increase in temperature develops with profound circulatory depression. In this stage the syndrome is irreversible, despite specific treatment with dantrolene. At present, the only reliable diagnostic test for susceptibility to malignant hyperthermia requires sampling of viable muscle for in vitro contracture tests with caffeine and halothane. Until our malignant hyperthermia diagnostic center was opened, such tests could not be performed in Israel. Since then we encountered a 22-year-old man who developed the partial picture of malignant hyperthermia syndrome during anesthesia for inguinal herniorrhaphy. He received dantrolene and recovered. 4 months later in vitro contracture tests with caffeine and halothane performed on biopsied muscle confirmed the diagnosis.

Adult↗