Positive End-expiratory Pressure Therapy Research Articles

Individualised, perioperative open-lung ventilation strategy during one-lung ventilation (iPROVE-OLV): a multicentre, randomised, controlled clinical trial

It is uncertain whether individualisation of the perioperative open-lung approach (OLA) to ventilation reduces postoperative pulmonary complications in patients undergoing lung resection. We compared a perioperative individualised OLA (iOLA) ventilation strategy with standard lung-protective ventilation in patients undergoing thoracic surgery with one-lung ventilation. This multicentre, randomised controlled trial enrolled patients scheduled for open or video-assisted thoracic surgery using one-lung ventilation in 25 participating hospitals in Spain, Italy, Turkey, Egypt, and Ecuador. Eligible adult patients (age ≥18 years) were randomly assigned to receive iOLA or standard lung-protective ventilation. Eligible patients (stratified by centre) were randomly assigned online by local principal investigators, with an allocation ratio of 1:1. Treatment with iOLA included an alveolar recruitment manoeuvre to 40 cm H2O of end-inspiratory pressure followed by individualised positive end-expiratory pressure (PEEP) titrated to best respiratory system compliance, and individualised postoperative respiratory support with high-flow oxygen therapy. Participants allocated to standard lung-protective ventilation received combined intraoperative 4 cm H2O of PEEP and postoperative conventional oxygen therapy. The primary outcome was a composite of severe postoperative pulmonary complications within the first 7 postoperative days, including atelectasis requiring bronchoscopy, severe respiratory failure, contralateral pneumothorax, early extubation failure (rescue with continuous positive airway pressure, non-invasive ventilation, invasive mechanical ventilation, or reintubation), acute respiratory distress syndrome, pulmonary infection, bronchopleural fistula, and pleural empyema. Due to trial setting, data obtained in the operating and postoperative rooms for routine monitoring were not blinded. At 24 h, data were acquired by an investigator blinded to group allocation. All analyses were performed on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, NCT03182062, and is complete. Between Sept 11, 2018, and June 14, 2022, we enrolled 1380 patients, of whom 1308 eligible patients (670 [434 male, 233 female, and three with missing data] assigned to iOLA and 638 [395 male, 237 female, and six with missing data] to standard lung-protective ventilation) were included in the final analysis. The proportion of patients with the composite outcome of severe postoperative pulmonary complications within the first 7 postoperative days was lower in the iOLA group compared with the standard lung-protective ventilation group (40 [6%] vs 97 [15%], relative risk 0·39 [95% CI 0·28 to 0·56]), with an absolute risk difference of -9·23 (95% CI -12·55 to -5·92). Recruitment manoeuvre-related adverse events were reported in five patients. Among patients subjected to lung resection under one-lung ventilation, iOLA was associated with a reduced risk of severe postoperative pulmonary complications when compared with conventional lung-protective ventilation. Instituto de Salud Carlos III and the European Regional Development Funds.

Clinical analysis of positive end-expiratory pressure ventilation in the treatment of 64 cases with neurogenic pulmonary edema

Objective To investigate the positive end-expiratory pressure (PEEP) ventilation in the treatment of neurogenic pulmonary edema. Method 64 patients with neurogenic pulmonary edema were treated with the timely use of positive end-expiratory pressure(PEEP) ventilation. Then the curative effect was observed. Result The symptoms of hypoxia, pulmonary edema were had a rapid improvement in ventilation with PEEP. the improvementof heart rate, respiratory rate, oxygen saturation, partial pressure of oxygen, carbon dioxide partial pressure had significant difference compared with that before treatment(P ＜ 0.01). Conclusion Neurogenic pulmonary edema patients treated with PEEP therapy had goved clinical effect. Key words: Pulmonary edema; Continuous positive airway pressure; Ventilators,mechanical

A novel mechanical lung model of pulmonary diseases to assist with teaching and training.

BackgroundA design concept of low-cost, simple, fully mechanical model of a mechanically ventilated, passively breathing lung is developed. An example model is built to simulate a patient under mechanical ventilation with accurate volumes and compliances, while connected directly to a ventilator.MethodsThe lung is modelled with multiple units, represented by rubber bellows, with adjustable weights placed on bellows to simulate compartments of different superimposed pressure and compliance, as well as different levels of lung disease, such as Acute Respiratory Distress Syndrome (ARDS). The model was directly connected to a ventilator and the resulting pressure volume curves recorded.ResultsThe model effectively captures the fundamental lung dynamics for a variety of conditions, and showed the effects of different ventilator settings. It was particularly effective at showing the impact of Positive End Expiratory Pressure (PEEP) therapy on lung recruitment to improve oxygenation, a particulary difficult dynamic to capture.ConclusionApplication of PEEP therapy is difficult to teach and demonstrate clearly. Therefore, the model provide opportunity to train, teach, and aid further understanding of lung mechanics and the treatment of lung diseases in critical care, such as ARDS and asthma. Finally, the model's pure mechanical nature and accurate lung volumes mean that all results are both clearly visible and thus intuitively simple to grasp.

Positive end-expiratory pressure in acute respiratory distress syndrome – an old yet mysterious tool

A recent study by Bruhn and colleagues, discussed here, confirms that even high levels of positive end-expiratory pressure (PEEP) – up to 20 cmH2O – may be applied in conditions of moderate acute respiratory distress syndrome. Such levels of PEEP were found to be safe in terms of their impact on cardiac output and adequacy of gastric mucosal perfusion once systemic haemodynamics were stabilized by adequate fluid replacement and catecholamine therapy. However, we strongly recommend that the reader does not oversimplify the conclusions of that study. PEEP therapy is not inherently safe with respect to haemodynamics and regional organ perfusion, but it may be used safely, even at high levels of up to 20 cmH2O, if haemodynamic therapy is appropriate.

PEEP--a "cheap" and effective lung protection.

Mechanical ventilation is a complex therapy with several different parameters which can be altered. In preterm and term infants, more attention has been paid to the levels of peak inspiratory pressure than to the positive end-expiratory pressure (PEEP). An awareness that lung protection can be conferred by an appropriate level of PEEP has increasingly stimulated a renewed interest in achieving the "best PEEP" strategy. We review the history of the introduction of PEEP therapy, some of the early demonstrations of its potential for mischief, the evidence on what levels of PEEP are appropriate in infants, some data concerning the lung-protective value of PEEP and finally some recent efforts at defining measures to determine the so-called "best PEEP". Some of this work has been performed in adults with the acute respiratory distress syndrome. In newborns, we are regrettably forced to conclude that there is, for the immediate present, no easy substitute for sensible clinical observations coupled with a judicious and cautious adjustment of PEEP. We anticipate that a more logical application of PEEP with individualisation of therapy, based on a pressure-volume relationship, will in future enable targeted tests of PEEP as a lung-protection strategy.

Beneficial effects of chest tube drainage of pleural effusion in acute respiratory failure refractory to positive end-expiratory pressure ventilation

Background: As part of an ongoing prospective evaluation of the response of acute respiratory failure (ARF) to ventilation with titrated amounts of positive end-expiratory pressure (PEEP), a subset of patients with a poor response to the initial application of PEEP and radiographic evidence of pleural effusion was identified. The effusion(s) were treated by tube thoracostomy (TT) to test the hypothesis that drainage would have a favorable effect on oxygenation and compliance in critically ill patients with substantial pulmonary dysfunction. Methods: Consecutive patients with ARF underwent a titrated progressive application of PEEP if arterial oxygen saturation was less than 90% on fraction of inspired oxygen less than 0.5. One or two thoracostomy tubes (TT) were placed afterward in patients with radiologic evidence of effusion who had a poor response to PEEP therapy. The lung injury score (LIS), PaO 2:FiO 2 (P:F), peak airway pressure, dynamic compliance, and TT output were recorded. Changes over time were analyzed by one-way analysis of variance with repeated measures. Results: Nineteen of 199 patients needed TT. LIS was 3.0 ± 0.1. Maximum PEEP was 16.6 ± 1.0 cm H 2O. TT drainage was 863 ± 164 ml in the first 8 hours. Mortality was 63% (12 of 19) but only 41% (74 of 180) in the patients who did not require TT ( p = 0.11). TT improved oxygenation and compliance immediately after insertion in 17 of 19 patients, and P:F remained statistically higher (245 ± 29 versus 151 ± 13, p < 0.01) 24 hours after TT drainage. There was no correlation between the volume of fluid removed and P:F either immediately ( R 2, 0.16) or 24 hours after TT ( R 2, 0.07). Conclusions: Drainage of pleural fluid resulted in a significant improvement in oxygenation in ARF patients with pleural effusions who were refractory to treatment with mechanical ventilation and PEEP. TT represents a simple and safe alternative for aggressive management of selected patients, obviating the inherent risk of pneumothorax with thoracentesis and possibly avoiding the need for more complex forms of support in this critically ill patient population. (Surgery 1998;123:137-43.)

Beneficial effects of chest tube drainage of pleural effusion in acute respiratory failure refractory to positive end-expiratory pressure ventilation

Background: As part of an ongoing prospective evaluation of the response of acute respiratory failure (ARF) to ventilation with titrated amounts of positive end-expiratory pressure (PEEP), a subset of patients with a poor response to the initial application of PEEP and radiographic evidence of pleural effusion was identified. The effusion(s) were treated by tube thoracostomy (TT) to test the hypothesis that drainage would have a favorable effect on oxygenation and compliance in critically ill patients with substantial pulmonary dysfunction. Methods: Consecutive patients with ARF underwent a titrated progressive application of PEEP if arterial oxygen saturation was less than 90% on fraction of inspired oxygen less than 0.5. One or two thoracostomy tubes (TT) were placed afterward in patients with radiologic evidence of effusion who had a poor response to PEEP therapy. The lung injury score (LIS), PaO2:FiO2 (P:F), peak airway pressure, dynamic compliance, and TT output were recorded. Changes over time were analyzed by one-way analysis of variance with repeated measures. Results: Nineteen of 199 patients needed TT. LIS was 3.0 ± 0.1. Maximum PEEP was 16.6 ± 1.0 cm H2O. TT drainage was 863 ± 164 ml in the first 8 hours. Mortality was 63% (12 of 19) but only 41% (74 of 180) in the patients who did not require TT (p = 0.11). TT improved oxygenation and compliance immediately after insertion in 17 of 19 patients, and P:F remained statistically higher (245 ± 29 versus 151 ± 13, p < 0.01) 24 hours after TT drainage. There was no correlation between the volume of fluid removed and P:F either immediately (R2, 0.16) or 24 hours after TT (R2, 0.07). Conclusions: Drainage of pleural fluid resulted in a significant improvement in oxygenation in ARF patients with pleural effusions who were refractory to treatment with mechanical ventilation and PEEP. TT represents a simple and safe alternative for aggressive management of selected patients, obviating the inherent risk of pneumothorax with thoracentesis and possibly avoiding the need for more complex forms of support in this critically ill patient population. (Surgery 1998;123:137-43.)

Effects of Positive End-Expiratory Pressure on Hepatic Venous Oxygenation in Dogs

Background : Positive end-expiratory pressure(PEEP) ventilation causes reduction in cardiac output and increase of intra-thoracic pressure, hence reduction of hepatic blood flow. The purpose of this study is to evaluate the changes of hepatic venous oxygen saturation, tension and content during increase and removal of PEEP and to evaluate hemodynamic variable which has the greatest effect on hepatic oxygenation. Method : Eight dogs were anethetised with 1.0 vol% isoflurane and 100% oxygen. After 30 minutes of stabilization of vital signs, PEEP were increased from 0 cmH2O to 5 cmH2O and 10 cmH2O and lowered to 0 cmH2O again, and hemodynamic data (heart rate, arterial blood pressure, central venous pressure(CVP), pulmonary arterial pressure, pulmonary arterial occlusion pressure and cardiac output(CO)) and hepatic venous oxygenation data (hepatic venous oxygen saturation(ShvO2), tension(PhvO2) and content(ChvO2)) were measured at each step. Results : CO, ShvO2, PhvO2 and ChvO2 decreased significantly at 10 cmH2O PEEP compared to the baseline and 5 cmH2O PEEP and CO, ShvO2 and ChvO2 increased signicantly with removal of PEEP. CVP increased significantly at 10 cmH2O PEEP and decreased significantly with PEEP removal. PEEP showed close correlationship with CO and CVP considering all steps of PEEP and PEEP removal. ShvO2 and PhvO2 showed most close correlationship with CO considering all steps of PEEP and PEEP removal. Conclusion : ShvO2 with PEEP therapy is dependent upon CO. Therefore cardiac output maintenance is essential during PEEP therapy. For exact evaluation of hepatic oxygenation, it is valuable to monitor ShvO2. (Korean J Anesthesiol 1998; 35: 861∼869)

CT evaluation of infradiaphragmatic air in patients treated with mechanically assisted ventilation: a potential source of error.

The purpose of this study was to describe the CT features of infradiaphragmatic air that may develop in patients after mechanically assisted ventilation, its location, its pathway of transdiaphragmatic dissection, and its extension into the abdomen. We retrospectively evaluated six consecutive adult patients with pneumomediastinum associated with positive end-expiratory pressure therapy who developed intraabdominal air and were imaged with CT in our institution-between 1993 and 1995. Abdominal CT examinations were reviewed and correlated with the clinical findings, follow-up examinations, and exploratory laparotomies in four patients. In four patients, air present in the anterior mediastinum (endothoracic fascia) was seen to extend into the anterior abdominal wall within the extraperitoneal space. In a fifth patient, the air was located extraperitoneally and intraperitoneally. In the remaining patient, air was present exclusively in the peritoneal cavity. In only two patients did we detect small amounts of air in the posterior retroperitoneum. In five patients, we also detected subcutaneous emphysema and/or air dissection into the muscle planes of the anterolateral abdominal wall. In patients on mechanically assisted ventilation, anterior mediastinal air can dissect through the diaphragm into the anterior abdominal extraperitoneal space. This anterior pathway of infradiaphragmatic extension of air can be erroneously diagnosed as intraperitoneal air, which may lead to unnecessary exploratory laparotomies. Also, anterior mediastinal air can enter the peritoneal cavity, particularly in patients with a history of median sternotomy.

Intraocular pressure during mechanical ventilation with different levels of positive end-expiratory pressure.

To determine the effect of positive end-expiratory pressure (PEEP) on intraocular pressure. Prospective, controlled, longitudinal, dual center study. In one group, patients served as their own control. In the second group, isolated determinations of intraocular pressure were made in mechanically ventilated patients receiving PEEP. Adult intensive care units of two university hospitals. Intraocular pressures were measured serially in eight patients during the recovery phase of different clinical conditions and in 22 patients receiving mechanical ventilation with PEEP > or = 10 cm H2O for > 24 hrs. Group A) In eight patients, a PEEP dose-response curve was established (PEEP 0, 5, 10, 15, and 0 cm H2O every 15 mins). Intraocular pressures were measured at the end of each period. Group B) In 22 patients, measurement of intraocular pressures were done while the patients received mechanical ventilation with PEEP > or = 10 cm H2O for at least > 24 hrs. In both groups, there was a positive correlation between the PEEP level and the central venous pressure (p < .05 in group A, and p < .03 in group B). No relationships between intraocular pressure and PEEP or central venous pressure were observed. However, there was a correlation between intraocular pressure and length of PEEP therapy (p < .03). We found ocular hypertension in only one patient (right eye intraocular pressure = 26 mm Hg; left eye intraocular pressure = 24 mm Hg). Short-term therapy with PEEP of < or = 15 cm H2O does not present a clinically important significant risk for intraocular pressure increase in a population with normal basal ocular tonometry. During prolonged mechanical ventilation with PEEP, increments in intraocular pressure may occur, but these increments appear to not be of a clinically relevant magnitude.

Pulmonary Complications following Tricyclic Antidepressant Overdose in an Adolescent

To report a case of pulmonary edema following a tricyclic antidepressant (TCA) overdose in an adolescent. A 14-year-old girl with a history of prior suicide attempts ingested 54 50-mg desipramine hydrochloride tablets (45 mg/kg ingestion). The patient developed a cardiac dysrhythmia and hypotension, which were successfully treated. She subsequently developed pulmonary edema and a clinical picture suggestive of adult respiratory distress syndrome (ARDS). She was successfully managed with fluid restriction, tracheal intubation, application of positive end-expiratory pressure (PEEP), and vasopressors. The patient was discharged without any clinical sequelae. Pulmonary complications secondary to TCA overdose have rarely been reported in children. We reviewed literature pertaining to the etiology, epidemiology, pathophysiology, and management of TCA-induced lung injury, as well as other case reports. We discuss the potential relationship between sequelae resulting from TCA ingestion (e.g., cardiac disturbances, hypotension, acidosis, gastric aspiration, pneumonia) and the development of ARDS and pulmonary edema, and relate this association to our patient. Pulmonary edema and a clinical picture suggestive of ARDS was noted in an adolescent girl who ingested a large quantity of desipramine. Her lung injury may have been the result of a variety of factors including hypotension, metabolic acidosis, possible aspiration, or a direct action on the lung parenchyma by desipramine. We attribute her favorable clinical outcome to early intervention consisting of tracheal intubation, PEEP, fluid restriction, and vasopressor therapy.

HIGH LEVEL POSITIVE END-EXPIRATORY PRESSURE (PEEP) MANAGEMENT IN TRAUMA ASSOCIATED ADULT RESPIRATORY DISTRESS SYNDROME (ARDS)

This study evaluated the effect of high-level positive end-expiratory pressure (PEEP) on mortality, barotrauma, intrapulmonary shunt (Qsp/Qt), and oxygen delivery (DO2) in posttraumatic adult respiratory distress syndrome (ARDS). All hypoxemic trauma patients admitted to the surgical intensive care unit (SICU) in 1989-1990 who received PEEP greater than 15 cm H2O were included. The PEEP was titrated to achieve an intrapulmonary shunt (Qsp/Qt) of approximately 0.20, and FIO2 was weaned to less than 0.50. Hemodynamic and pulmonary variables at four distinct intervals were recorded. Fifty-nine patients received PEEP greater than 15 cm H2O. Of these, 19 patients died of severe head injury or uncontrollable hemorrhage (16 within 48 hours). Forty (29 male, 11 female) were evaluated in detail. The PEEP levels ranged from 18-50 cm H2O with a mean of 27. PaO2/FIO2 ratios and Qsp/Qt improved as PEEP therapy was titrated. Cardiac index and oxygen delivery were maintained or improved throughout PEEP therapy by transfusion and fluid resuscitation, with a mean maximum positive fluid balance of 21.1 L and an average of 51 units of blood and blood products transfused per patients during their SICU stay. Twenty-nine (73%) had evidence of barotrauma, the majority being pneumothoraces clearly related to the initial trauma. Only three (7.5%) had evidence of barotrauma not related to trauma or line insertion. Eight of 40 patients (20%) died. Mean ISS and RTS for the entire group were 32 and 5.88, respectively. We conclude that titration of PEEP to achieve a Qsp/Qt of approximately 0.20 is an attainable goal. This was accomplished with minimal hemodynamic effects or barotrauma and a low mortality rate.

Optimal positive end-expiratory pressure therapy in infants and children with acute respiratory failure

Optimal positive end-expiratory pressure therapy in infants and children with acute respiratory failure

Optimal positive end-expiratory pressure therapy in infants and children with acute respiratory failure.

Positive end-expiratory pressure (PEEP) has become a mainstay in the treatment of hypoxemic acute respiratory failure (ARF). Whereas PEEP improves arterial oxygen tension by decreasing intrapulmonary shunting, it may also impair cardiac output and hence decrease systemic oxygen transport. Inasmuch as optimizing oxygen transport is a goal of therapy in ARF, we sought to determine if the level of PEEP that results in maximal oxygen transport could be estimated from measurements of compliance of the respiratory system (Crs) or PaO2. We studied the effects of PEEP application on cardiorespiratory parameters in 15 children who required mechanical ventilation for ARF. Static Crs, PaO2, central venous and arterial blood pressures, indicator dilution cardiac index (CI), and oxygen transport were determined at 0, 3, 6, 9, 12, and 15 cm H2O PEEP. PaO2 increased significantly at PEEP levels greater than or equal to 9 cm H2O (p less than 0.001), while CI fell by 15% between 0 and 15 cm end-expiratory pressure (p less than 0.02). Crs and oxygen transport did not change significantly with increasing levels of PEEP. The level of PEEP resulting in maximal oxygen transport ranged from 0 to 15 cm H2O, and in all patients it corresponded to PEEP of best CI. At levels of PEEP above that associated with maximal oxygen transport, CI and oxygen transport fell significantly, while PaO2 continued to rise. No relationship between Crs and oxygen transport was observed. In our normovolemic patients with ARF, neither PaO2 nor Crs predicted PEEP of maximal oxygen transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer-controlled optimization of positive end-expiratory pressure.

Positive end-expiratory pressure (PEEP) is a standard treatment for patients with refractory hypoxemia due to an acute restrictive pathology. The therapeutic range of PEEP can be quite narrow. PEEP therapy has been optimized using invasive variables such as oxygen transport and pulmonary shunt, and noninvasive variables such as compliance; however, the measurements are complex. We constructed a computerized PEEP-optimization system consisting of a Siemens 900C ventilator, Siemens prototype sulfur hexafluoride analyzer, Siemens 940 lung mechanics analyzer, and a DEC 11/23 microcomputer. The user may choose from three different noninvasive PEEP titration algorithms: maximizing static total respiratory system compliance (CTR), maximizing functional residual capacity(FRC)-based compliance (CFRC), and normalizing FRC. The device was tested in six dogs with pulmonary injury induced by oleic acid. The system was constrained to 3-cm H2O PEEP steps at 20-min intervals. The algorithm normalizing FRC reached optimal PEEP levels in 40 min, with a mean difference from the desired FRC of 15 +/- 48 (SEM) ml. This corresponds to a mean percent error of 1.0% +/- 2.63%. The CFRC and CTR algorithms reached optimal PEEP levels in 60 and 40 min, respectively, and maintained a maximal compliance for 85% of the time. This system provides fully automated noninvasive PEEP titration and is flexible enough to incorporate easily any other PEEP titration algorithms. It should improve patient care by guaranteeing that PEEP therapy is truly optimized throughout the patient's recovery.

Positive end-expiratory pressure therapy in adults with special reference to acute lung injury: a review of the literature and suggested clinical correlations.

SHAPIRO, BARRY A. MD; CANE, ROY D. MB, B CH (RAND), FFA(SA); HARRISON, RONALD A. MD Author Information

Positive End-expiratory Pressure in Acute Lung Injury

Positive end-expiratory pressure (PEEP) is essential to the successful support and treatment of many patients with gas exchange and pulmonary function derangement. The vast majority of adult patients requiring PEEP therapy suffer from acute lung injury—an intrinsic metabolic malfunction of lung parenchyma secondary to severe systemic insult. The purpose of this article is to provide the clinician with our interpretation of the presently available scientific information on which rational clinical application may be based.

Current concepts: positive end-expiratory pressure in adult respiratory failure.

Almost 15 years have passed since positive end-expiratory pressure (PEEP) was described as a treatment for the adult respiratory-distress syndrome.1 PEEP was observed to increase diminished functional residual capacity and to ameliorate arterial hypoxemia, which until then had often been untreatable even in patients given very high concentrations of oxygen. Recent reviews have addressed in detail the mechanisms of lung injury in adult respiratory-distress syndrome2 , 3 and the rationale for the use of PEEP in that syndrome.4 The purpose of this paper is to scrutinize specific controversial issues related to PEEP therapy that have arisen with its widespread use. We will . . .

The effect of positive end-expiratory pressure ventilation (PEEP) on cerebral blood flow and cerebrospinal fluid pressure in goats.

The effect of cerebral blood flow (CBF) and cerebrospinal fluid pressure (CSFP) of mechanical ventilation with positive end-expiratory pressure (PEEP) at 5, 10, and 15 cm H2O was studied in 23 paralyzed, ventilated goats which were divided into three treatment groups. Group I received no volume expansion agent to counteract the hemodynamic effects of PEEP. Group II received normal saline to maintain a constant arterial blood pressure (BP), and Group III received a mannitol solution for BP maintenance. In all three groups there were similar increases in central venous pressure (CVP) of approximately 2.5 times the zero PEEP level at 15 cm H2O PEEP (P less than 0.001). In Group I, BP fell an average of 32 per cent, cardiac output fell 47 per cent and cisternal CSFP increased 40 per cent above zero PEEP levels at 15 cm H2O PEEP (P less than 0.01). CBF in this group was decreased 18 per cent when compared with the zero PEEP baseline at 15 cm H2O PEEP (P less than 0.008). In Group II animals there were no significant changes in BP or cardiac output (CO) at any of the PEEP levels. CSFP in this group, at 15 cm H2O PEEP, increased 84 per cent above the baseline zero level and CBF decreased 32 per cent at 15 cm H2O PEEP when compared to the zero PEEP level (P less than 0.008). In Group III there were no significant reductions in BP or CO. Unlike Groups I and II, no significant changes in CFSP were observed at any level of PEEP. In addition, CBF in this group did not change significantly from the zero-PEEP baseline level any level of PEEP. Thus, when PEEP therapy is associated with substantial decreases in BP and CO, CBF may decrease as well. Maintenance of BP and CO by volume expansion with a crystalloid solution resulted in a greater reduction in CBF than in the untreated group but maintenance of BP and CO by mannitol infusion resulted in maintenance of CBF at the baseline, pre-PEEP level. The authors conclude that brain interstitial fluid pressure is an important variable in the determination of cerebral blood flow during ventilation with PEEP.

Intensive medical treatment of severe acute pancreatitis.

AbstractTherapeutic measurements for acute pancreatitis depend on the severity of the disease and its complications. Since complications of acute pancreatitis may develop at any time, patients should be admitted to an intensive care unit for assessment (and frequent reassessment) of the severity of the disease and of the development of complications; they should remain in the intensive care unit for the first 48 hours at least, even if no signs of shock are apparent. The only exceptions to this rule are mild cases without signs of peritonitis. Basic therapy should include relief of pain, total fasting, nasogastric suction, parenteral replacement of fluids, electrolyte, albumin, and blood, and antibiotics. Hyperglycemia should be corrected and heparin should be given in cases of disseminated intravascular coagulation. In renal insufficiency, peritoneal dialysis is important, and in respiratory complications, humidified oxygen or artificial ventilation including positive end expiratory pressure therapy should be applied. Although the effect of peritoneal dialysis has been proven only in animal experiments and in retrospective studies in man, it is recommended in severe cases for shock therapy and for correction of electrolyte imbalance when ascites is present, even before anuria occurs.