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C Putensen

Publications and source records attributed to C Putensen.

At least 55 records · Page 3Linked to original sources
PubMed1995

Interfacing between spontaneous breathing and mechanical ventilation affects ventilation-perfusion distributions in experimental bronchoconstriction.

The effect of interfacing between spontaneous and mechanical ventilation on ventilation-perfusion (VA/Q) distributions was determined during pressure-support ventilation (PSV) and in the presence and absence of spontaneous breathing during biphasic positive airway pressure (BIPAP) in 10 pigs with methacholine-induced bronchoconstriction. Whereas BIPAP without spontaneous breathing provides full and PSV breath-to-breath synchronized ventilatory support, BIPAP allows unrestricted spontaneous breathing throughout the mechanical cycle. Compared with BIPAP with and without spontaneous breathing, PSV effected an increase in ventilatory rate (p < 0.05) and a higher minute ventilation (VE) (p < 0.05). Spontaneous breathing during BIPAP accounted for 15 +/- 1% of the VE and increased cardiac output (CO) from 4.5 +/- 0.2 to 5.3 +/- 0.2 L/min (p < 0.05), Pao2 from 55 +/- 3 to 80 +/- 4 mm Hg (p < 0.05), and oxygen delivery (DO2) from 442 +/- 39 to 630 +/- 43 ml/min (p < 0.05). PSV did not increase CO, Pao2, and DO2. Spontaneous breathing did not affect oxygen consumption. During BIPAP spontaneous breathing accounted for a 15 +/- 2% decrease (p < 0.05) in blood flow to shunt units and a 16 +/- 2% increase (p < 0.05) in the perfusion of normal VA/Q units. Perfusion of shunt and normal VA/Q units was similar during PSV and BIPAP without spontaneous breathing. Dead space ventilation decreased with spontaneous breathing during BIPAP by 12% compared with PSV (p < 0.05). Dispersion of ventilation distribution was lowest during BIPAP. Uncoupling of spontaneous and mechanical ventilation during BIPAP improved gas exchange by allowing better VA/Q matching during experimental bronchoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[The prone position in ARDS. A successful therapeutic strategy].

As early as 1974, Brian advocated the prone position for ventilated patients. He suggested that this position might enhance ventilation of the dorsal parts of the lungs, thereby improving oxygenation. These considerations have been confirmed by several experimental and clinical studies. Better secretion removal, decreased intrapulmonary shunting, and an increased FRC are thought to be responsible for the observed improvement of oxygenation. However, the prone position never became very popular in the clinical treatment of the adult respiratory distress syndrome (ARDS). Routine performance of thoracic CT scans in ARDS patients demonstrated preferential distribution of pathological densities in the dependent lung areas. The prone position therefore could possibly benefit these patients, as shown by two recent studies. The aim of our study was to evaluate the influence of repeatedly turning the patient to the prone position on gas exchange and thoracic CT findings in multiple-trauma patients. METHODS. Seven ventilated intensive care patients with severe ARDS (Murray Score > 2.5, Quotient > 0.7, mean airway pressure > 18 cm H2O, thoracic CT scan showing dorsal atelectases) were included in the study. Patients were turned from the supine to the prone position at 12-h intervals using an air-cushion bed (Mediscus, Austria). Redistribution of dystelectatic or atelectatic dependent lung areas was verified by means of repeated thoracic CT scans (Figs. 1, 8). RESULTS. The patients were intermittently turned for 6.5 +/- 1.1 days. The course of gas exchange is shown in Figs. 2 and 3. Initially, improvement of the respiratory quotient could only be achieved during prone positioning, from the 2nd day in the supine position as well. Intrapulmonary shunting showed a similar trend (Figs. 4 and 5). No significant changes in cardiovascular parameters could be observed. Control thoracic CT scans showed uniform reduction of atelectases in dependent lung areas (Figs. 1 and 8). The inspiratory fraction of oxygen could be reduced significantly as of the 2nd day (Fig. 7). Constant levels of positive end-expiratory pressure and tidal volume were associated with decreasing mean and plateau airway pressures (Fig. 6). DISCUSSION. Repeatedly turning the patient to the prone position produced long-lasting improvement of arterial oxygenation, which persists up to the end of the weaning process. This is in good accordance with other studies, however, this is the first study to report an observation period of more than 6 days of repeatedly turning the patient. These positive effects on gas exchange can be attributed to sudden improvement of the ventilation-perfusion ratio within the lung areas that become dependent after turning to the prone position. Due to reduced hydrostatic pressure and relative hyperventilation, previously collapsed alveoli are recruited in the lung areas that become non-dependent after turning to the prone position.

Adult↗
PubMed1994

Effect of interfacing between spontaneous breathing and mechanical cycles on the ventilation-perfusion distribution in canine lung injury.

BACKGROUND: Improved matching between ventilation and perfusion (VA/Q) has been proposed to be a major advantage of partial ventilatory support compared with controlled mechanical ventilation. This study was designed to determine whether a difference in gas exchange exists between partial ventilatory support techniques that allow unsupported spontaneous breathing to occur during any phase of the mechanical ventilatory cycle and those that provide mechanical support for each spontaneous inspiratory effort. METHODS: Ten anesthetized dogs with oleic acid-induced lung injury received, in random order, pressure-support ventilation (PSV) and airway pressure-release ventilation (APRV) with and without spontaneous breathing using equivalent airway pressure limits. Gas exchange was assessed by conventional blood gas analysis and by estimating the VA/Q distributions using the multiple inert-gas elimination technique. RESULTS: During APRV, spontaneous breathing accounted for 10 +/- 1% of the total expiratory minute ventilation. Breath-to-breath ventilatory support with PSV resulted in the highest total expiratory minute ventilation (P < 0.05). During spontaneous breathing with APRV, cardiac output increased from 3.9 +/- 0.3 to 4.6 +/- 0.41.min-1 (P < 0.05), arterial oxygen tension from 75 +/- 3 to 107 +/- 8 mmHg (P < 0.05), and oxygen delivery from 567 +/- 47 to 719 +/- 73 ml.kg.min-1 (P < 0.05). PSV did not increase cardiac output, arterial oxygen tension, and oxygen delivery. Spontaneous breathing did not increase oxygen consumption. During APRV spontaneous breathing accounted for a 13 +/- 2% decrease (P < 0.05) in blood flow to shunt units (VA/Q < 0.005) and a 14 +/- 2% increase (P < 0.05) in the perfusion of normal VA/Q units (0.1 < VA/Q < 10). Pulmonary blood flow distribution to shunt and normal VA/Q units was similar during PSV and APRV without spontaneous breathing. Dead space (VA/Q > 100) ventilation decreased by 6% during APRV with spontaneous breathing compared with PSV (P < 0.05). CONCLUSIONS: Spontaneous breathing superimposed on mechanical ventilation contributes to improved VA/Q matching and increased systemic blood flow. Apparently, the spontaneous contribution to a mechanically assisted breath during PSV is not sufficient to counteract the VA/Q maldistribution of positive pressure lung insufflation during acute lung injury.

Animals↗
PubMed1994

Subglottic positive end-expiratory pressure in extubated patients recovering from acute lung injury.

OBJECTIVE: To examine the glottic function in extubated patients recovering from acute lung injury by simultaneous measurement of airway opening and subglottic airway pressures while patients are breathing at ambient pressure and receiving continuous positive airway pressure by a face mask. DESIGN: Descriptive, prospective study. SETTING: Intensive care unit at a university hospital. PATIENTS: Ten patients who required continuous positive airway pressure of at least 7 cm H2O in order to restore gas exchange after mechanical ventilation for acute lung injury. INTERVENTIONS: Spontaneous breathing at ambient airway pressure and with continuous positive airway pressures of 5 and 10 cm H2O via face mask. MEASUREMENTS AND MAIN RESULTS: Intratracheal pressure, airway opening pressure, and airflow at the airway opening were measured. Breathing at ambient pressure resulted in significantly higher end-expiratory intratracheal pressure than end-expiratory airway opening pressure (p < .01). No significant differences between end-expiratory intratracheal pressure and end-expiratory airway opening pressure were observed during breathing with continuous positive airway pressures of 5 and 10 cm H2O. A significant end-expiratory airflow at the airway opening (p < .01), observed during ambient pressure breathing, was not detectable while the patient received mask continuous positive airway pressure. The partial pressure of oxygen in the arterial blood (Pao2) increased significantly while patients breathed with 10 cm H2O, but not while patients breathed 5 cm H2O continuous positive airway pressure compared with breathing at ambient pressure (p < .05). CONCLUSIONS: Our data imply that patients recovering from acute lung injury create an intratracheal positive end-expiratory pressure by braking the expiratory airflow, probably by glottic narrowing. Despite compensatory glottic narrowing, extubated patients with reduced lung function may benefit from higher levels of continuous positive airway pressure.

Adolescent↗
PubMed1994

Timing of pressure release affects power of breathing and minute ventilation during airway pressure release ventilation.

OBJECTIVES: To evaluate the effects of interference between spontaneous and mechanical breaths on the power of breathing (rate at which work is done) and ventilatory support during airway pressure release ventilation. DESIGN: Multitrial tests under simulated clinical conditions using a mechanical respiratory system model. SETTING: A research laboratory at a university medical center. INTERVENTIONS: Simulated spontaneous breathing augmented with continuous positive airway pressure and airway pressure release ventilation. Variation in synchrony between spontaneous breathing and mechanical ventilation was accomplished by adjusting the time lag between detection of the spontaneous inspiration and the airway pressure release from 0 to 3 secs in increments of 0.25 secs. MEASUREMENTS AND MAIN RESULTS: Pressures and volumes were measured at the inlet of the lung and chest wall compartment of the respiratory system model. Pressure and volume changes measured at the inlet of the chest wall compartment were used to generate pressure/volume loops and to calculate the power of the spontaneous breathing. Minute ventilation was greater (p < .01) during all airway pressure release ventilation settings compared with those values of continuous positive airway pressure. Nonconflicting airway pressure release ventilation was associated with a higher minute ventilation (p < .001) than asynchronous airway pressure release ventilation. When spontaneous inspiration was synchronous with restoration of continuous positive airway pressure, minute ventilation was lower (p < .001) than during nonconflicting airway pressure release ventilation settings. Power of spontaneous breathing was highest when airway pressure release and spontaneous inspiration coincided, and lowest when spontaneous inspiration and restoration of continuous positive airway pressure were synchronized. Power of breathing was significantly lower during nonconflicting than during asynchronous airway pressure release ventilation (p < .01). No difference was observed between the power of spontaneous breathing and airway pressure release ventilation either with spontaneous expiration synchronized with airway pressure release or with nonconflicting airway pressure release ventilation. When calculated per liter of ventilation, power of spontaneous breathing was significantly lower (p < .01) during all airway pressure release ventilation settings compared with continuous positive airway pressure. CONCLUSION: Asynchronous airway pressure release may increase the power of spontaneous breathing and reduce effective mechanical ventilatory support during airway pressure release ventilation. A clinical study is required to assess the effect of synchronous and asynchronous interference between spontaneous and mechanical breaths during airway pressure release ventilation.

Airway Resistance↗
PubMed1994

Ventilation-perfusion distributions during mechanical ventilation with superimposed spontaneous breathing in canine lung injury.

Biphasic positive airway pressure (BIPAP) allows unrestricted spontaneous breathing throughout mechanical ventilation. Effects of spontaneous breathing during BIPAP on pulmonary gas exchange were studied on a randomized basis in 12 dogs with oleic acid-induced lung injury using the multiple inert gas elimination technique. Spontaneous breathing during BIPAP, accounting for 10% of minute ventilation (VE), increased PaO2 from 61 +/- 2 to 78 +/- 3 mm Hg (mean +/- SE) (p < 0.01), cardiac output from 4.2 +/- 0.3 to 4.6 +/- 0.3 L/min (p < 0.05), and oxygen delivery from 537 +/- 51 to 716 +/- 58 ml/kg/min (p < 0.05), whereas oxygen consumption and total VE remained unchanged. Improved pulmonary gas exchange caused by better ventilation/perfusion (VA/Q) matching was indicated by a 17 +/- 3% decrease (p < 0.01) in blood flow to shunt units (VA/Q < 0.005), a 15 +/- 3% increase (p < 0.05) in perfusion of normal VA/Q units (0.1 < VA/Q < 10), and a 6 +/- 3% reduction in ventilation of dead space (VA/Q > 100) areas (p < 0.05). Spontaneous breaths superimposed on mechanical ventilation may convert shunt VA/Q units to normal by increased ventilation of poorly or nonventilated units and/or increase blood flow to previously minimal or nonperfused areas.

Animals↗
PubMed1994

Effect of endogenous and inhaled nitric oxide on the ventilation-perfusion relationships in oleic-acid lung injury.

Previous investigations have shown that the ventilation-perfusion (VA/Q) mismatch caused by acute lung injury can be alleviated either by inducing vasodilation in ventilated lung units with inhaled nitric oxide (NO) or by inhibiting the synthesis of endogenous NO, which opposes hypoxic pulmonary vasoconstriction. To determine the effects of a combination of these interventions, we evaluated cardiopulmonary function and VA/Q distributions in 10 dogs with oleic acid-induced lung injury. Each animal received, in random order, zero or 40 ppm of NO in inspiratory gas, with and without intravenous infusion of NG-monomethyl-L-arginine (L-NMMA) (5 mg/kg/h). The multiple inert-gas elimination technique was used to estimate VA/Q distributions. Systemic L-NMMA administration alone did not affect VA/Q inequality and gas exchange, but increased pulmonary and systemic vascular resistance. Inhaled NO improved gas exchange by redistributing blood flow from shunt units to lung units with a nearly ideal VA/Q ratio, without affecting pulmonary or systemic vascular resistance. Improved VA/Q matching and gas exchange was most pronounced when NO was inhaled in the presence of systemic L-NMMA. Inhalation of NO reversed the pulmonary but not the systemic vasoconstriction caused by L-NMMA. These results suggest that endogenous NO release is not limited to hypoxic lung regions in animals with oleic acid-induced lung injury. Inhaled NO reversed L-NMMA-induced pulmonary vasoconstriction and improved VA/Q matching by selectively dilating the pulmonary vasculature in ventilated lung units.

Animals↗
PubMed1994

Continuous positive airway pressure modulates effect of inhaled nitric oxide on the ventilation-perfusion distributions in canine lung injury.

OBJECTIVES: The present study was designed to evaluate if continuous positive airway pressure (CPAP) augments the effect of nitric oxide (NO) inhalation on matching between ventilation and perfusion (VA/Q) during acute lung injury. DESIGN: Prospective, randomized study. SETTING: A research laboratory at a university medical center. SUBJECTS: Ten anesthetized mongrel dogs with oleic acid-induced lung injury. INTERVENTIONS: Zero or 40 parts per million of NO in the inspiratory gas, with and without 10 cm H2O CPAP in random order. MEASUREMENTS AND MAIN RESULTS: Gas exchange was assessed by estimating the VA/Q distributions using the multiple inert gas elimination technique. Application of CPAP decreased blood flow to shunt units by 26 +/- 2 percent (mean +/- SD) and increased the fraction of cardiac output to normal VA/Q units (VA/Q ratio of 0.1 to 10) by 26 +/- 2 percent (p < 0.05). Inhalation of NO during CPAP accounted for a further 10 +/- 2 percent decrease in the blood flow to shunt units and an 8 +/- 2 percent increase in the fraction of the cardiac output to normal VA/Q units (p < 0.05). Inhalation of NO alone had no significant effect on the VA/Q distributions. Inhalation of NO decreased mean transmural pulmonary artery pressure (Ppatm) both without (Ppatm from 30 +/- 2 to 23 +/- 2 mm Hg; PVR from 323 +/- 44 to 228 +/- 43 dynes.s .cm-5; p < 0.05) and with CPAP (Ppatm from 25 +/- 2 to 20 +/- 2 mm Hg; PVR from 255 +/- 30 to 173 +/- 31 dynes.s.cm-5; p < 0.05). CONCLUSIONS: Although pulmonary vascular resistance can be lowered with NO inhalation alone, recruitment of gas exchange units with CPAP is necessary to produce a beneficial effect of NO inhalation on VA/Q matching and oxygenation. When recruitment of gas exchange units with CPAP brings gaseous NO in contact with enough pulmonary blood vessels, NO-induced vasodilation will augment VA/Q matching by a steal mechanism.

Administration, Inhalation↗
PubMed1994

Effect of neuromuscular blockade on the elastic properties of the lungs, thorax, and total respiratory system in anesthetized pigs.

OBJECTIVE: To evaluate the effect of neuromuscular blockade on the elastic properties of the lungs, thorax, and total respiratory system in pigs anesthetized to suppress spontaneous breathing. DESIGN: Prospective, randomized, experimental study. SETTING: A research laboratory at a university medical center. SUBJECTS: Eight healthy, anesthetized pigs, weighing 22 to 25 kg. INTERVENTIONS: Pigs, with and without muscular blockade, were mechanically ventilated during an infusion of sodium pentobarbital that was titrated to suppress spontaneous breathing activity. MEASUREMENTS AND MAIN RESULTS: No significant differences were observed between pressure/volume curves of the lungs, the chest wall, and the total respiratory system, as determined by inflating and deflating the lungs during anesthesia, with or without neuromuscular blockade, in random order. Functional residual capacity was 985 +/- 87 mL with neuromuscular blockade and 997 +/- 78 mL without neuromuscular blockade (NS). A comparison of the total respiratory system, lung, and chest wall compliances obtained with and without neuromuscular blockade showed high correlations (total respiratory system compliance [r2 = .86]; chest wall compliance [r2 = .83]). CONCLUSION: Neuromuscular blockade does not alter the elastic properties of the lungs, chest wall, or total respiratory system in mechanically ventilated pigs receiving sodium pentobarbital anesthesia to suppress spontaneous breathing efforts.

Analysis of Variance↗
PubMed1994

Biphasic positive airway pressure (BIPAP)--a new mode of ventilatory support.

Biphasic Positive Airway Pressure (BIPAP) can be described as pressure controlled ventilation in a system allowing unrestricted spontaneous breathing at any moment of the ventilatory cycle. It can also be described as a Continuous Positive Airway Pressure (CPAP) system with a time-cycled change of the applied CPAP level. As with a pressure controlled, time-cycled mode, the duration of each phase (T(high), T(low)) as well as the corresponding pressure levels (P(high), P(low)) can be adjusted independently. Depending on the spontaneous breathing activity, BIPAP can be subdivided into: no spontaneous breathing: CMV-BIPAP; spontaneous breathing at the lower pressure level: IMV-BIPAP; spontaneous breathing at the upper pressure level: APRV-BIPAP; spontaneous breathing at both CPAP levels: genuine BIPAP. Since it enables progressive transition from controlled to all levels of augmented mechanical ventilation, BIPAP appears to be a suitable mode for the entire period of mechanical ventilation of the patient. There are difficulties neither in choosing the correct moment for switching nor the further respiratory management of the ventilated patient under BIPAP. The necessary adaptation (ventilation, oxygenation) can be individualized on the basis of blood gas analyses. An increase or reduction of the invasivity of ventilation can be attained without any problems with BIPAP. Furthermore, spontaneous breathing of the patient does not necessitate any switching of the mode of ventilation. The transition from controlled to augmented ventilation is smooth. BIPAP enables the therapist to let the patient breathe freely even under the most invasive ventilation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1993

Comparison of mask and nasal continuous positive airway pressure after extubation and mechanical ventilation.

OBJECTIVE: To examine the effects of continuous positive airway pressure applied via face masks and nose masks on the change in functional residual capacity and gas exchange. DESIGN: Descriptive and prospective study. SETTING: Intensive care unit of a university hospital. PATIENTS: Ten patients with acute lung injury who had required mechanical ventilation. INTERVENTIONS: Continuous positive airway pressure at a level of 10 cm H2O applied in random order via face and nose masks. MEASUREMENTS AND MAIN RESULTS: Both continuous positive airway pressure methods resulted in an almost identical increase of functional residual capacity. During nasal continuous positive airway pressure, the increase in functional residual capacity was 294 +/- 82 mL. During mask continuous positive airway pressure, the increase in functional residual capacity was 290 +/- 85 mL. PaO2 increased and the alveolar-arterial oxygen tension/alveolar oxygen tension quotient decreased significantly during mask continuous positive airway pressure and nasal continuous positive airway pressure at a level of 10 cm H2O. Two patients showed a periodic change in their breathing patterns; they took a few breaths at an increased lung volume, followed by one deep expiration caused by mouth opening. Change in mask pressure was negligible in these two patients. Using a visual analog scale (10 = highly comfortable; 0 = severely uncomfortable), the patients rated nasal continuous positive airway pressure (8.6 +/- 0.9) significantly more comfortable than mask continuous positive airway pressure (2.6 +/- 0.8). CONCLUSION: The major advantages of continuous positive airway pressure (the improvement of functional residual capacity and oxygen transfer) can also be achieved with nasal continuous positive airway pressure in the postextubation period in patients who have been mechanically ventilated for acute lung injury.

Acute Disease↗
PubMed1993

Selecting ventilator settings according to variables derived from the quasi-static pressure/volume relationship in patients with acute lung injury.

Knowledge of the pressure/volume (P/V) relationship of the lung may allow selection of tidal volume and positive end-expiratory pressure (PEEP) to optimize gas exchange without adversely affecting lung function or hemodynamics. Ten patients with acute lung injury were stabilized on controlled mechanical ventilation, based on conventional practice, using criteria from arterial blood gas data. The P/V relationship was determined under quasi-static conditions (end-expiratory and end-inspiratory, no flow periods > 0.8 s) during mechanical ventilation with an automated procedure that changed PEEP in a stepwise fashion. Differences in expiratory tidal volumes before and after a change in PEEP equaled the change in functional residual capacity (delta FRC). PEEP was set above the lowest point of the steepest section of the P/V curve (inflection pressure) to prevent end-expiratory lung collapse. Inspiratory tidal volumes (VTI) were adjusted to avoid an end-inspiratory lung volume reaching the flat part of the P/V curve. Averaged delta FRC versus PEEP curves were shifted to the left and the slope increased 1, 6, and 12 h after changing ventilator settings compared to baseline (P < 0.01). Averaged baseline delta FRC versus PEEP curves showed a marked inflection pressure that decreased after adjusting ventilator settings (P < 0.01). PEEP was increased from 7.4 +/- 1.8 cm H2O (baseline) to 11.9 +/- 1.6 cm H2O (1 h) (P < 0.001) according to measured baseline inflection pressures. Simultaneously, VTI had to be reduced from 759 +/- 161 mL (baseline) to 664 +/- 101 mL (1 h) (P < 0.01) to avoid end-inspiratory overinflation. To maintain minute volume constant ventilator frequency was increased from 14 +/- 1.2 (baseline) to 16 +/- 1.2 breaths/min (1 h) (P < 0.01). Maximum quasi-static compliance of 38 +/- 7 mL/cm H2O (baseline) increased to 46 +/- 9 mL/cm H2O (1 h) (P < 0.01). Maintaining FIO2 constant, PaO2 increased from a baseline of 90 +/- 16 mm Hg to 122 +/- 24 mm Hg (1 h) (P < 0.001), to 130 +/- 20 mm Hg (6 h) (P < 0.01), and to 138 +/- 19 mm Hg (12 h) (P < 0.01). Intrapulmonary shunt decreased from 0.28 +/- 0.08 (baseline) to 0.14 +/- 0.05 (12 h) (P < 0.001). Hemodynamic variables did not change. Our data suggest that using variables derived from a quasi-static P/V loop during mechanical ventilation under muscle paralysis is clinically superior compared to blood gas criteria for titration of ventilator settings.

Adult↗
PubMed1992

Tidal volume, breathing frequency, and oxygen consumption at different pressure support levels in the early stage of weaning in patients without chronic obstructive pulmonary disease.

The objective of this study was to evaluate the influence of different PSV levels on VT, F, VO2 in the early weaning phase of patients without chronic obstructive pulmonary disease. These parameters were tested for the predictive power for the success of the weaning. Patients on SIMV were studied during the first weaning attempt with PSV. Depending on their ventilatory support demands after 24 h they were divided into responders (patients breathing on CPAP) and nonresponders (patients being on a more invasive ventilatory mode). 14 ICU patients without pre-existing pulmonary disease being ventilated for at least 3 days entered the study. 2 of them could be studied a second time after failing the first weaning attempt. Beside the level of ventilatory support no other changes (drugs, nutrition) were allowed. VO2, VT, F were measured by a computer controlled, metabolic unit connected to the expiratory port of a Siemens Servo Ventilator. In addition, airway pressures, arterial pressure and heart rate were recorded. The measurements were performed at PSV of 5, 10 and 20 cmH2O. Arterial blood-gases were drawn at the end of each 60 min lasting PS period. Responders and nonresponders could be separated by the response of VO2, VT and F to a change in PS 10 to PS 20 cmH2O. Patients who significantly increased VT and significantly decreased F did not fulfil our weaning criteria. Our responders did not show a significant change in these two parameters, but a significant increase in VO2 at PS 20 cmH2O could be observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Plasma lignocaine concentrations associated with extradural analgesia in patients with and without multiple organ failure.

We have measured plasma concentrations of lignocaine after thoracic extradural analgesia with continuous infusion of lignocaine in eight intensive care patients with chest wall trauma or after major upper abdominal surgery. Four patients developed multiple organ failure (MOF). Plasma concentrations of lignocaine in arterial blood were measured 4, 8, 24 and 48 h after a continuous infusion of lignocaine was commenced in the extradural space. Plasma concentrations of lignocaine were greater in all patients with MOF (range 2.7-5.1 micrograms ml-1) than in patients without MOF (range 0.8-1.2 micrograms ml-1). Because plasma concentrations in patients with MOF were within the low toxic range, extradural infusion of lignocaine should only be considered in intensive care patients without MOF or when plasma concentrations of lignocaine are monitored.

Adult↗
PubMed1992

Comparison of postoperative respiratory function after laparoscopy or open laparotomy for cholecystectomy.

Cholecystectomy performed via laparotomy is associated with reduction of lung volumes including functional residual capacity that may lead to postoperative hypoxia and atelectasis. Laparoscopic cholecystectomy is associated with faster recovery compared to open laparotomy and cholecystectomy. To determine whether laparoscopic cholecystectomy was associated with less pulmonary dysfunction, 20 patients (ASA Physical Status I) undergoing elective cholecystectomy were randomly assigned to surgical teams performing either laparoscopy or open laparotomy for cholecystectomy. Patients in whom one or the other surgical technique had to be performed for medical or psychologic indications were excluded from the study. A standardized anesthetic technique and postoperative analgesic regimen were used. Forced vital capacity and forced expiratory volume in 1 s; functional residual capacity determined by a closed-circuit, constant volume helium dilution technique; and arterial O2 and CO2 tensions were measured preoperatively and at 6, 24, and 72 h postcholecystectomy. Forced vital capacity and forced expiratory volume in 1 s were significantly greater (P less than 0.05) in the laparoscopy compared to the laparotomy group at 6, 24, and 72 h postoperatively. Forced vital capacity relative to preoperative values was significantly (P less than 0.05) greater in patients with laparoscopy (24 h, 70 +/- 14%; 72 h, 91 +/- 6%) compared to open laparotomy (24 h, 57 +/- 23%; 72 h, 77 +/- 14%). Similarly, forced expiratory volumes in 1 s relative to preoperative values were significantly (P less than 0.05) greater in patients with laparoscopy (24 h, 85 +/- 13%; 72 h, 92 +/- 9%) compared to open laparotomy (24 h, 54 +/- 22%; 72 h, 77 +/- 11%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Atrial natriuretic factor release during hypovolemia and after volume replacement.

OBJECTIVE: To examine plasma atrial natriuretic factor activity during hypovolemia and after vascular volume replacement. DESIGN: Prospective, descriptive study. SETTINGS: Scene of emergency, Emergency Department, and the ICU of a university hospital. PATIENTS: A total of 47 trauma patients with evidence of hypovolemia were grouped according to their major injury into a thoracic injury group (15 patients; mean Injury Severity Score = 38.5 +/- 3.1 [SEM], Hospital Trauma Index = 14.1 +/- 0.7), an abdominal injury group (14 patients; Injury Severity Score = 36 +/- 3.3, Hospital Trauma Index = 14 +/- 0.9), and a severe head injury group (18 patients; Injury Severity Score = 23 +/- 1.5, Hospital Trauma Index = 10 +/- 0.6). MEASUREMENTS AND MAIN RESULTS: Measurements were taken at the scene of emergency; after volume replacement in the Emergency Department; and after 3, 7, 12, 24, 36 hrs and on day 5 in the ICU. In all groups, the average plasma atrial natriuretic factor levels were increased at the scene of emergency and declined significantly to normal values with volume replacement. In the thoracic injury group, plasma atrial natriuretic factor activity decreased from 253 +/- 73 to 115 +/- 83 pg/mL (p less than .0017); in the abdominal injury group, plasma atrial natriuretic factor activity decreased from 194 +/- 42 to 91 +/- 24 pg/mL (p less than .006); in the severe head injury group, plasma atrial natriuretic factor activity decreased from 167 +/- 28 to 70 +/- 13 pg/mL (p less than .02) with volume replacement. Plasma atrial natriuretic factor levels at the scene of emergency were significantly (252 +/- 73 vs. 167 +/- 28 pg/mL; p less than .05) higher in the thoracic injury group and in the abdominal injury group (194 +/- 42 vs. 167 +/- 28 pg/mL; p less than .05), as compared with the severe head injury group. CONCLUSIONS: In trauma patients, plasma atrial natriuretic factor concentrations were markedly increased in patients with untreated hypovolemia and were decreased to normal values with vascular volume replacement. Thus, atrial natriuretic factor seems to play an important physiologic role during hypovolemia.

Abdominal Injuries↗