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Objective: Right-to-left shunting across a patent foramen ovale may occur in acute respiratory distress syndrome as a result of pulmonary hypertension and positive-pressure mechanical ventilation. The shunt may worsen the hypoxemia. The objective of our study was to determine the prevalence, clinical implications, and prognosis of patent foramen ovale shunting during acute respiratory distress syndrome., Design: Prospective study., Setting: Medical intensive care unit of a university hospital in Créteil, France., Patients: Two hundred three consecutive patients with acute respiratory distress syndrome., Interventions: Patent foramen ovale shunting was detected by using transesophageal echocardiography with modified gelatin contrast. Moderate-to-large shunting was defined as right-to-left passage of at least 10 bubbles through a valve-like structure within three cardiac cycles after complete opacification of the right atrium. In 85 patients without and 31 with shunting, the influence of the positive end-expiratory pressure level on shunting was studied., Measurements and Results: The prevalence of moderate-to-large patent foramen ovale shunting was 19.2% (39 patients). Compared to those in the group without shunting, the patients in group with shunting had larger right ventricle dimensions, higher pulmonary artery systolic pressure, and a higher prevalence of cor pulmonale. Compared to patients without shunting, patients with shunting had a poorer Pa(O(2))/Fi(O(2)) ratio response to positive end-expiratory pressure, more often required prone positioning and nitric oxide as adjunctive interventions, and had fewer ventilator-free and intensive care unit-free days within the first 28 days., Conclusions: Moderate-to-large patent foramen ovale shunting occurred in 19.2% of patients with acute respiratory distress syndrome, in keeping with findings from autopsy studies. Patent foramen ovale was associated with a poor oxygenation response to positive end-expiratory pressure, greater use of adjunctive interventions, and a longer intensive care unit stay.

Purpose of Review: Critical care is a special area in which research needs to take place, because of the severity of the diseases which are treated there, but it is also a place where research faces a lot of hurdles and difficulties. The main cause of difficulties is the consent issue, as most patients cannot consent for themselves. Recently, all national legislations in the countries of the European Union have been modified to include the provisions of directive 2001/20., Recent Findings: This review article provides a summary of the recent literature concerning the issue of consent for clinical care research such as how the surrogate consent reflects the view of the patient and how time consuming and inaccurate can be the consultation of a community before the start of a trial with a waiver of consent. Another hurdle to research is the rigidity of our legislations concerning clinical research, especially the absence of a simplified way for low or no-risk research. This article shows how this situation is potentially deleterious and how it could ultimately forbid low-risk research., Summary: Critical research remains a domain in which research on patients is difficult and controversial. Regulation can be difficult to implement, largely inadequate or uselessly complicated. Intensive care physicians need to keep pressure on politicians and lawmakers to constantly explain the necessity and specificities of critical care research.

Purpose of the Review: Emergency research is possible only if informed consent is waived. Recent legislations have specifically addressed this issue, both in the US and in Europe., Recent Findings: In the US, a specific regulation was enacted in 1996. Due to the added complexity, few trials have used this design. The necessity to inform the community in which a trial is supposed to take place, though feasible, is burdensome and time consuming. In the EU, directive 2001/20/CE forgot to specify particular rules for research in emergency conditions. After 2004, national legislations were supposed to implement the directive in order to enhance homogeneity within Europe, but actually showed an extreme diversity, with some countries allowing waiver of consent in emergency situations and others refusing it., Summary: Due to the active lobbying of emergency and intensive care specialists, the situation is slowly improving, with most national legislations recognizing the specificities and difficulty of emergency research.

Purpose of the Review: Historically, clinical research and patient care have long been intertwined. Until the mid-1970s, physicians in both North America and Europe considered that research on their patients was an integral part of the care that they delivered to them. In the United States, it was after the recommendations of the Belmont report, in 1979, that both medical activities were clearly separated. But, in Europe, the concept of "individual direct benefit from research" is still prevailing in some national legislation., Recent Findings: The revision of the Declaration of Helsinki and the implementation of a European directive (in 2001) on clinical research in Member States' national laws have prompted a reappraisal of the distinction of research with and without individual benefit. Several recent articles have shown that this concept is flawed for several reasons: first, the commitment of a physician to his patient is inherently different in these two situations; second, it masks the possible conflict of interest, which can be financial or not; third, it perpetuates the "therapeutic conception" and reduces the obligation for a physician-investigator to implement supplemental procedures aimed at enhancing the safety of study patients., Summary: The European directive on clinical research, voted on in 2001 and still in the process of being implemented in national laws of the European Union Member States, mandates clarification of these issues. All European investigators are concerned because the framework of regulations governing clinical research will be markedly altered. The replacement of the distinction between research with and without direct benefit by the evaluation of the risk/benefit ratio by ethics committees is one of the most important changes that is due to happen soon.

Objective: Recommendations for making and implementing decisions to forgo life-sustaining therapy in intensive care units have been developed in the United States, but the extent that they are realized in practice has yet to be measured., Design: Prospective, multicenter, 4-wk study. For each patient with an implemented decision to forgo life-sustaining therapy, the deliberation and decision implementation procedures were recorded., Setting: French intensive care units., Patients: All consecutive patients admitted to 26 French intensive care units., Interventions: None., Measurements and Main Results: Of 1,009 patients admitted, 208 died in the intensive care unit. A decision to forgo life-sustaining therapy was implemented in 105 patients. The number of supportive treatments forgone was 2.3 +/- 1.7 per patient. Decisions to forgo sustaining therapy were preceded by 3.5 +/- 2.5 deliberation sessions. Proxies were informed of the deliberations in 62 (59.1%) cases but participated in only 18 (17.1%) decisions. The patient's perception of his or her quality of life was rarely evaluated (11.5%), and only rarely did the decision involve evaluating the patient's wishes (7.6%), the patient's religious values (7.6%), or the cost of treatment (7.6%). Factors most frequently evaluated were medical team advice (95.3%), predicted reversibility of acute disease (90.5%), underlying disease severity (83.9%), and the patient's quality of life as evaluated by caregivers (80.1%)., Conclusions: A decision to withhold or withdraw life-sustaining therapy was implemented for half the patients who died in the French intensive care units studied. In many cases, the decision was taken without regard for one or more factors identified as relevant in U.S. guidelines.

Objective: Anxiety and depression may have a major impact on a person's ability to make decisions. Characterization of symptoms that reflect anxiety and depression in family members visiting intensive care patients should be of major relevance to the ethics of involving family members in decision-making, particularly about end-of-life issues., Design: Prospective multicenter study., Setting: Forty-three French intensive care units (37 adult and six pediatric); each unit included 15 patients admitted for longer than 2 days., Patients: Six hundred thirty-seven patients and 920 family members., Interventions: Intensive care unit characteristics and data on the patient and family members were collected. Family members completed the Hospital Anxiety and Depression Scale to allow evaluation of the prevalence and potential factors associated with symptoms of anxiety and depression., Measurements and Main Results: Of 920 Hospital Anxiety and Depression Scale questionnaires that were completed by family members, all items were completed in 836 questionnaires, which formed the basis for this study. The prevalence of symptoms of anxiety and depression in family members was 69.1% and 35.4%, respectively. Symptoms of anxiety or depression were present in 72.7% of family members and 84% of spouses. Factors associated with symptoms of anxiety in a multivariate model included patient-related factors (absence of chronic disease), family-related factors (spouse, female gender, desire for professional psychological help, help being received by general practitioner), and caregiver-related factors (absence of regular physician and nurse meetings, absence of a room used only for meetings with family members). The multivariate model also identified three groups of factors associated with symptoms of depression: patient-related (age), family-related (spouse, female gender, not of French descent), and caregiver-related (no waiting room, perceived contradictions in the information provided by caregivers)., Conclusions: More than two-thirds of family members visiting patients in the intensive care unit suffer from symptoms of anxiety or depression. Involvement of anxious or depressed family members in end-of-life decisions should be carefully discussed.

Partial liquid ventilation (PLV) developed considerably in the clinical and experimental fields during the past few years. In addition to improved oxygenation and lung mechanics by perfluorocarbon (PFC) administration, recent animal studies have tried to optimize PLV by evaluating the most appropriate ventilatory mode to use during PLV and by adjusting the best level of positive end-expiratory pressure (PEEP). Other pathophysiological aspects of acute lung injury that may be positively affected by liquid ventilation have been studied, including regional blood flow redistribution, reduction in ventilator-induced lung injury, and antiinflammatory properties of PFC. Although the precise dosing of PFC is debated, evidence from several experimental studies supports the use of smaller doses of PFC because larger doses increase the occurrence of baro- and volutrauma. In the clinical field, after promising data from preliminary studies, an international randomized controlled trial is on the verge of completion.

Background: Although the use of external positive end-expiratory pressure (PEEP) is recommended for patients with intrinsic PEEP, no simple method exists for bedside titration. We hypothesized that the occlusion pressure, measured from airway pressure during the phase of ventilator triggering (P0.1t), could help to indicate the effects of PEEP on the work of breathing (WOB)., Methods: Twenty patients under assisted ventilation with chronic obstructive pulmonary disease were studied with 0, 5, and 10 cm H2O of PEEP while ventilated with a fixed level of pressure support., Results: PEEP 5 significantly reduced intrinsic PEEP (mean +/- SD, 5.2 +/- 2.4 cm H2O at PEEP 0 to 3.6 +/- 1.9 at PEEP 5; P < 0.001), WOB per min (12. 6 +/- 6.7 J/min to 9.1 +/- 5.9 J/min; P = 0.003), WOB per liter (1.2 +/- 0.4 J/l to 0.8 +/- 0.4 J/l; P < 0.001), pressure time product of the diaphragm (216 +/- 86 cm H2O. s-1. min-1 to 155 +/- 179 cm H2O. s-1. min-1; P = 0.001) and P0.1t (3.3 +/- 1.5 cm H2O to 2.3 +/- 1.4 cm H2O; P = 0.002). At PEEP 10, no further significant reduction in muscle effort nor in P0.1t (2.5 +/- 2.1 cm H2O) occurred, and transpulmonary pressure indicated an increase in end-expiratory lung volume. Significant correlations were found between WOB per min and P0.1t at the three levels of PEEP (P < 0.001), and between the changes in P0.1t versus the changes in WOB per min (P < 0.005), indicating that P0.1t and WOB changed in the same direction. A decrease in P0.1 with PEEP indicated a decrease in intrinsic PEEP with a specificity of 71% and a sensitivity of 88% and a decrease in WOB with a specificity of 86% and a sensitivity of 91%., Conclusion: These results show that P0.1t may help to assess the effects of PEEP in patients with intrinsic PEEP.

Institutional Review Boards have been recently audited in the US, and a great deal of concerns and criticisms appeared in the medical literature and the lay press. Globally, these comments questioned the efficiency of Institutional Review Boards in fulfilling their basic mission, the protection of patients subjected to biomedical research. Vulnerable populations, such as psychiatric and incompetent patients, were particularly identified. In intensive care units, conducting research in critically ill patients unable to give informed consent themselves remains a hot issue. Several possibilities have been proposed and assessed in the recent past: pre-emptive (global) consent, proxy consent from a surrogate, deferred consent, and, more recently, waiver of consent for emergency research. Obviously, the inability to deal with this major obstacle (i.e. obtaining consent from incompetent patients) would lead to the cessation of any research in intensive care units, which is hardly acceptable and certainly unethical. Recent published studies have reported over-mortality in treatment groups, posing new questions: who should be informed of those failures, and when? What is the role of Institutional Review Boards in preventing such an issue? What type of indemnity should be proposed to the family of deceased patients during a trial?

Background: The morphologic effect of positive end-expiratory pressure (PEEP) and of two tidal volumes were studied by computed tomography to determine whether setting the tidal volume (Vt) at the upper inflection point (UIP) of the pressure-volume (P-V) curve of the respiratory system or 10 ml/kg have different effects on hyperinflation and alveolar recruitment., Methods: Alveolar recruitment and hyperinflation were quantified by computed tomography in nine patients with the acute respiratory distress syndrome (ARDS). First, end expiration was compared without PEEP and with PEEP set at the lower inflection point of the P-V curve; second, at end inspiration above PEEP, a reduced Vt set at the UIP (rVt) and a standard 10 ml/kg Vt (Vt) ending above the UIP were compared. Three lung zones were defined from computed tomographic densities: hyperdense, normal, and hyperinflated zones., Results: Positive end-expiratory pressure induced a significant decrease in hyperdensities (from 46.8 +/- 18% to 38 +/- 15.1% of zero end-expiratory pressure (ZEEP) area; P < 0.02) with a concomitant increase in normal zones (from 47.3 +/- 20.9% to 56.5 +/- 13.2% of the ZEEP area; P < 0.05), and a significant increase in hyperinflation (from 8.1 +/- 5.9% to 17.8 +/- 12.7% of ZEEP area; P < 0.01). At end inspiration, a significant increase in hyperinflated areas was observed with Vt compared with rVt (33.4 +/- 17.8 vs. 26.8 +/- 17.3% of ZEEP area; P < 0.05), whereas no significant difference was observed for both normal and hyperdense zones., Conclusions: Positive end-expiratory pressure promotes alveolar recruitment; increasing Vt above the UIP seems to predominantly increase hyperinflation.

Background: Limited data suggest that increased resistance to flow within endotracheal tubes (ETT) may occur in patients whose lungs are mechanically ventilated for more than 48 h, especially when airway humidification is inadequate. This could lead to sudden ETT obstruction or induce excessive loading during spontaneous breathing., Methods: Twenty-three such patients were randomly assigned to three types of airway humidifier based on three different working principles: a Fisher Paykell hot water system (n = 7), a Pall BB2215 heat and moisture exchanger (HME) hydrophobic filter (n = 8), and a Dar Hygrobac 35254111 HME hygroscopic filter (n = 8). The decrease in internal pressure along the ETT and the flow rate were measured in each patient every 2 days. An "effective inner diameter" was derived from these measurements and allowed the inner ETT configuration to be monitored., Results: On the first day of intubation, the mean diameter was similar in the three groups, and was slightly smaller than the in vitro diameter (mean +/- SD: 7.6 +/- 0.6 mm for Fisher-Paykell, 7.7 +/- 0.4 for Pall, and 7.5 +/- 0.4 for Dar). The mean diameter tended to decrease from day to day. At the end of the study, the overall reduction in mean diameter was significantly greater with the hydrophobic HME (Pall) than with the two other systems (Pall: -6.5 +/- 4% vs. 2.5 +/- 2.5% for Dar and 1.5 +/- 3% for Fisher-Paykell; P < 0.01 with analysis of variance). The same was true of the mean reduction in effective inner ETT diameter expressed per day of ventilation (-1.6 +/- 1.5% per day for Pall vs. -0.5 +/- 0.4% for Dar and -0.2 +/- 0.4% for Fisher-Paykell; P < 0.01). In four patients, the ETT became obstructed and emergency repeated tracheal intubation was required. The Pall HME and the Fisher-Paykell system were being used in three and one patient, respectively. Before obstruction, the reduction in ETT diameter was significantly greater for these four patients than for the remaining 23 patients (7.8 +/- 1.4% vs. 3.1 +/- 4.1%; P < 0.01)., Conclusions: During prolonged mechanical ventilation, significant alterations in inner ETT configuration occur frequently and are influenced by the type of humidification device used. In vivo monitoring of ETT mechanical properties might be clinically useful.

Objective: To determine the occurrence rate of bacteremia associated with transesophageal echocardiography in intensive care unit (ICU) patients., Design: A prospective study of 139 patients undergoing transesophageal echocardiography., Setting: The medical ICU of a tertiary referral teaching hospital., Patients: One hundred thirty-nine ICU patients (mean age 58 yrs) who underwent transesophageal echocardiography., Interventions: Blood samples were systematically drawn for aerobic and anaerobic culture at the following times: before (blood culture 1), at the end of (blood culture 2), and 30 mins after (blood culture 3) transesophageal echocardiography examinations., Measurements and Main Results: The mean duration of transesophageal echocardiography was 35 mins (range 7 to 120). One hundred thirty-four patients received mechanical ventilation; 125 patients had a nasogastric tube. Fifty-one patients had one or more underlying conditions that usually justify antimicrobial prophylaxis of bacterial endocarditis before high-risk procedures. Fifty-six patients did not receive any antibiotic treatment at the time of transesophageal echocardiography. In 114 patients, the three blood cultures were negative. In six patients, transesophageal echocardiography was performed during a preexisting bacteremia. A contamination (only one positive blood culture of the three sampling times) with coagulase-negative staphylococci occurred in four patients at blood culture 1, five patients at blood culture 2, and six patients at blood culture 3. Contamination with Corynebacterium species occurred in two patients at blood culture 2. In one patient receiving cefotaxime and netilmicin, blood culture 1 was sterile and blood cultures 2 and 3 yielded coagulase-negative staphylococci. In one patient receiving no antibiotic treatment, blood culture 1 was sterile and blood cultures 2 and 3 yielded Enterococcus faecalis. None of these two patients received a specific antibiotic treatment or developed any secondary septic focus., Conclusions: The overall frequency of bacteremia induced by transesophageal echocardiography in ICU patients was 1.4% (two of 139 patients) (95% confidence interval 0.2% to 5.1%). The frequency did not differ whether patients received antibiotics before transesophageal echocardiography (one [1.2%] of 83 patients) or not (one [1.8%] of 56 patients) (p = .96). Therefore, routine antimicrobial prophylaxis does not appear justified before transesophageal echocardiography in ICU patients.

Background: Pressure-controlled (PCV) and pressure-controlled inverse ratio ventilation (PCIRV) have been proposed instead of volume-controlled conventional ratio ventilation (VC) with positive end-expiratory pressure (PEEP) for patients with adult respiratory distress syndrome (ARDS). The advantages advocated with the use of PCIRV are to decrease airway pressures and to improve gas exchange. However, most studies did not compare PCIRV and VC while keeping both the level of ventilation and end-expiratory alveolar pressure (total-PEEP) constant., Methods: Nine patients with moderate to severe ARDS (lung injury score 2.83 +/- 0.18) had their lungs ventilated with VC, PCV with a conventional ratio (I:E 1:2; PC 1/2), and PCIRV (I:E 2:1 and 3:1; PC 2/1 and PC 3/1, respectively). Ventilator settings were adjusted to keep tidal volume, respiratory rate, FIo2, and total-PEEP constant in every mode. With each mode, a complete set of ventilatory, hemodynamic, and gas exchange parameters was obtained after 30 min., Results: In PC 3/1, the data obtained could not be strictly compared to the other modes because total-PEEP was higher despite external-PEEP being set at zero. For the other modes (VC, PC 1/2, and PC 2/1), despite differences in peak airway pressures, no difference was noted for end-inspiratory and end-expiratory static airway pressures (which better reflect alveolar pressures) nor for lung and respiratory system compliance. Arterial oxygenation deteriorated slightly with PC 2/1 despite a higher mean airway pressure, whereas alveolar ventilation tended to be slightly, but not significantly, improved (lower PaCo2). A decrease in systolic and mean arterial pressure also was observed with PC 2/1 without other significant hemodynamic change., Conclusions: In this prospective controlled study, no short-term beneficial effect of PCV or PCIRV could be demonstrated over conventional VC with PEEP in patients with ARDS.

Objective: To evaluate physician accuracy in predicting patients' hemodynamic profiles, associated morbidities, rates of change in therapy resulting from catheterization, and the outcome variations associated with such change before the insertion of a pulmonary artery catheter., Design: Prospective, descriptive, cohort study with no interventions., Setting: Medical intensive care unit (ICU) of a university hospital., Patients: One hundred twelve catheterizations performed in 112 patients without acute myocardial infarction. In 43 cases, catheterizations were indicated because of circulatory shock that was unresponsive to two standard therapeutic measures., Measurements and Main Results: Before catheterization, physicians were asked to predict the hemodynamic profile of the patients who were to be catheterized, and to provide a plan for therapy. After catheterization, each patient's chart was reviewed and compared with precatheterization predictions. Hemodynamic profiles were correctly predicted in only 56% of the cases. Information obtained from pulmonary artery catheters prompted changes in therapy in 58% of all cases and in 63% of patients in shock who were unresponsive to standard therapy. Modifications varied among hemodynamic profiles, from 33% (fluid overloaded) to 87% (hypovolemia). Complications occurred in 11 catheterizations, but only two complications required therapy (pneumothorax [n = 1] and one episode of arrhythmia). No systemic infection occurred, and all blood cultures sampled through catheters before the catheters were withdrawn were sterile. In the entire group of patients, those patients in whom catheterization induced a change in therapy and those patients in whom no change in therapy occurred had similar precatheterization characteristics and mortality rates. However, in the subgroup of patients in shock that was unresponsive to standard therapy, the mortality rate was significantly lower when the assessment of hemodynamic data led to a change in therapy (59% vs. 100%, p = .009), despite identical precatheterization characteristics., Conclusions: Prompted by assessment of pulmonary artery catheter measurements in patients with circulatory shock who were unresponsive to standard therapeutic measures, a change in therapy for these patients was associated with an improved prognosis, independent of other variables influencing outcome.

A trial of separation from mechanical ventilation may induce an abnormal respiratory pattern and a maldistribution of ventilation-to-perfusion ratios (VA/Q), especially in patients with chronic obstructive pulmonary disease. This study was designed to assess the effects of three different modes of ventilation on the distribution of global and also regional VA/Q in eight patients with chronic obstructive pulmonary disease recovering from acute respiratory failure who remained dependent on mechanical ventilation after more than 5 days of attempted separation from the ventilator. VA/Q distribution was assessed using the multiple inert gas and isotopic scanning methods after 30 min each of controlled mechanical ventilation (CMV), 10 cmH2O inspiratory pressure support, and spontaneous breathing (SB). Controlled ventilation was provided at a respiratory rate ranging from 12 to 18 breaths per min and a tidal volume of 8 ml.kg-1. In comparison to CMV, SB resulted in a decrease in tidal volume (from 512 +/- 144 to 301 +/- 102 ml, P less than 0.01), and an increase in respiratory rate (from 15.5 +/- 3.2 to 27.3 +/- 15.0 breaths per min, P less than 0.05), which increased dead space (+7.1% of minute ventilation), cardiac output (+36%), and the perfusion to areas of low VA/Q (+8.9% of cardiac output) (P less than 0.05, P less than 0.001, and P less than 0.05, respectively). Isotopic scans revealed a horizontal craniocaudal difference of VA/Q in all modes, with the lowest VA/Q zones at the basal part of the lungs (mean basal VA/Q 0.58 in SB and 1.05 in CMV).(ABSTRACT TRUNCATED AT 250 WORDS)

Breathing through an endotracheal tube and a demand valve may increase the work performed by the respiratory muscles. Inspiratory pressure support (PS) is known to reduce this work and might therefore compensate for this increased requirement. To test this hypothesis, we measured the work of breathing (WOB) in 11 patients whose tracheas were intubated. Five had no intrinsic lung disease, but six had chronic obstructive lung disease. We compared WOB measurements taken under several sets of conditions: during assisted breathing at four levels of PS, during unassisted breathing and connection to a T-piece, and after extubation of the trachea. During unassisted breathing via the ventilator circuit (PS set at 0 cmH20), the WOB per minute was greater than that after extubation, with a mean increase (+/- standard deviation) of 68 +/- 38% (10.3 +/- 5.1 vs. 6.5 +/- 3.7 J.min-1, P less than 0.01). While breathing through the T-piece, the WOB was 27 +/- 18% greater than after tracheal extubation (8.2 +/- 5.1 vs. 6.5 +/- 3.7 J.min-1, P less than 0.05). The principal reason why inspiratory work decreased after extubation was that the ventilatory requirement decreased. For each patient, we determined retrospectively, after extubation, the level of PS that had reduced WOB to its postextubation value and obtained levels ranging from 3.4 to 14.4 cmH2O. The PS level at which additional WOB was compensated for, was greater in patients with chronic lung disease than in those free of lung disease (12.0 +/- 1.9 vs. 5.7 +/- 1.5 cm H2O, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The authors studied the hemodynamic effects of rapidly weaning from mechanical ventilation (MV) 15 patients with severe chronic obstructive pulmonary disease (COPD) and cardiovascular disease who were recovering from acute cardiopulmonary decompensation. In each patient, 10 min of spontaneous ventilation (SV) with supplemental oxygen resulted in reducing the mean esophageal pressure (X +/- SD, + 5 +/- 3 to -2 +/- 2.5 mmHg, P less than .01) and increasing cardiac index (CI) 3.2 +/- 0.9 to 4.3 +/- 1.3 1/min/M2, P less than .001), systemic blood pressure (BP 77 +/- 12 to 90 +/- 11 mmHg, P less than .001), heart rate (HR 97 +/- 12 to 112 +/- 16 beats/min, P less than .001), and, most importantly, transmural pulmonary artery occlusion pressure markedly increased (PAOPtm 8 +/- 5 to 25 +/- 13 mmHg, P less than .001), mandating a reinstitution of MV. In four patients with left ventricular (LV) catheters, the PAOP correlated with the LV end-diastolic pressure during both MV and SV. Gated blood pool imaging showed SV increased the LV end-diastolic volume index (65 +/- 24 to 83 +/- 32/M2, P less than .002) with LV ejection fraction unchanged. Patients were treated for a mean of 10 days with diuretics, resulting in a reduction of blood volume (4.55 +/- 0.9 1 to 3.56 +/- 0.55 1) and body weight (-5 kg, P less than .001). Subsequently, nine of the 15 patients were weaned successfully from mechanical ventilation with unchanged PAOP.

Measurement of total (lung plus chest wall) pulmonary compliance is routinely obtained in mechanically ventilated patients by dividing the tidal volume (VT) by the airway pressure (Paw) gradient from end-inspiration to end-expiration. In order to obtain the pressure-volume (P-V) tracing during inspiration, we developed a method using a continuous and slow (1.7 L/min) oxygen inflow. When gas flow is kept constant, changes in lung volume are proportional to time and do not require direct measurement. In 22 patients, P-V curves traced using the continuous-flow method were identical to those obtained from the syringe method. The advantages of the inflow method are simplicity, reproducibility, and better visualization of the initial part of P-V curve.

Angiography was used to diagnose atrial septal aneurysm in a 46-yr-old man suffering from recurrent pulmonary emboli, who had normal venograms of his lower extremities. This case demonstrates the usefulness of searching for sources of emboli other than deep venous thrombosis, but illustrates the limits of two-dimensional echocardiography in diagnosing atrial septal aneurysm.

Delayed-onset pulmonary edema complicating severe diabetic ketoacidosis was observed twice in one patient. Hemodynamic measurements during the second episode showed normal transmural pulmonary capillary wedge pressure, suggesting an alteration in alveolocapillary permeability. Hyperventilation and acidosis may underlie this alteration. Vigorous fluid therapy, while decreasing oncotic pressure, may also contribute to the pulmonary edema. The two episodes in one patient suggest that pulmonary microvascular diabetic angiopathy may predispose some diabetics with severe ketoacidosis to increased-permeability pulmonary edema.

When positive end-expiratory pressure (PEEP) is applied to normal lungs, the pulmonary artery occlusion pressure (PAOP) may reflect alveolar pressure and not left ventricular end-diastolic pressure (LVEDP). The reliability of PAOP measurements has been questioned when PEEP levels greater than 10 cm H2O are applied. To verify whether this disparity occurs in patients with severe lung injury, the authors simultaneously measured both PAOP and LVEDP at 0, 10, and 16-20 cm H2O PEEP in 12 supine patients with severe adult respiratory distress syndrome (ARDS). In all patients, the radiographic location of the PA catheter tip was at or below the level of the posterior border of the left atrium. A close correlation was found between PAOP and LVEDP at each level of PEEP. In only six of 35 simultaneous measurements was the PAOP-LVEDP gradient 2 mmHg or more (2-3 mmHg in four, and 4 mmHg in two). In five patients, the highest PEEP level was 4-9 cm H2O greater than LVEDP; however, no gradient was measured between LVEDP and PAOP. The authors conclude that, in severe ARDS, a close correspondence between PAOP and LVEDP is maintained despite applying PEEP levels up to 20 cm H2O, suggesting that, in ARDS, surrounding pathology prevents transmitted alveolar pressure from collapsing adjacent pulmonary vessels.