Insights into how universal, tax-funded, single payer health systems manage their waiting lists: A review of the literature.

Background: A conspicuous consequence of gatekeeping arrangements in universal, tax-funded, single-payer health care systems is the long waiting times. Besides limiting equal access to care, long waiting times can have a negative impact on health outcomes. Long waiting times can create obstacles in a patient's care pathway. Organization for Economic Co-operation and Development (OECD) countries have implemented various strategies to tackle this issue, but there is little evidence for which approach is the most effective. This literature review examined waiting times for ambulatory care. Objective: The aim was to identify the main policies or combinations of policies universal, tax-funded, and single-payer healthcare systems have implemented to improve the governance of outpatient waiting times. Methods: Starting from 1040 potentially eligible articles, a total of 41 studies were identified via a 2-step selection process. Findings: Despite the relevance of the issue, the literature is limited. A set of 15 policies for the governance of ambulatory waiting time was identified and categorized by the type of intervention: generation of supply capacity, control of demand, and mixed interventions. Even if a primary intervention was always identifiable, rarely a policy was implemented solo. The most frequent primary strategies were: guidelines implementation and/or clinical pathways, including triage, guidelines for referral and maxim waiting times (14 studies), task shifting (9 studies), and telemedicine (6 studies). Most studies were observational, with no data on costs of intervention and impact on clinical outcomes.

Characteristics and determinants of population acceptance of COVID-19 digital contact tracing: a systematic review.

BACKGROUND AND AIM: As recently outlined in the WHO-ECDC Indicator framework (1) to evaluate the public health effectiveness of digital proximity tracing solutions, one of the main barriers to digital contact tracing (DCT) is population acceptance, which, in turns, is influenced by digital literacy, attitudes and practice. DCT came to public prominence during the COVID-19 pandemic but evidence on its population acceptance have not been comprehensively analyzed.  Methods: We carried out a systematic review (PROSPERO: CRD42021253668) following the PRISMA guidelines to collect, systematize and critically appraise the available evidence on population DCT acceptance.  Original studies reporting on different measures of population DCT acceptance were included. CONCLUSIONS: The systematic review was based on 41 articles meeting our a priori defined inclusion criteria, comprising aa total of 186144 surveyed subjects, 50000 tweets, 5025 Reddit posts and 714 written comments. Data extraction and synthesis required a qualitative outcome grouping, performed ex-post, in 14 different benchmarks components. They constitute a narrative analysis of actionable points for public health policy. Population acceptance is a key component of  DCT effective adoption and infection control during infectious diseases outbreaks. Assessing DCT acceptance's determinants in different settings, populations an cultural contexts it is of fundamental importance to inform the planning, implementation and monitoring of public health interventions. The results of our in-depth qualitative and quantitative analysis  will provide context for prospective improvements and actionable items and should guide future research aimed at exploring how digitalization can serve people-centred care.

Outcomes Related to Antiplatelet Therapy in a High-Risk ST-Segment Elevation Myocardial Infarction Population: A Retrospective Real-World Analysis of an Italian ECMO Center.

AIM: To evaluate outcomes related to antiplatelet therapy in patients with ST-elevation myocardial infarction (STEMI) admitted to the San Gerardo Hospital in Monza, an extracorporeal membrane oxygenation (ECMO) reference center in the Monza-Brianza area. METHODS: This retrospective study enrolled patients with STEMI hospitalized between 2013 and 2017. RESULTS: This study included 653 patients (mean age: 67.5 years, 71% male). Across the study period, ticagrelor use showed consistent increases, from 22% of patients during 2013 to 85% in 2017. Cardiac arrest prehospitalization occurred in 100 patients (15.3%), either at home (n = 85, 13.0%) or during transfer (n = 15, 2.3%); 46 patients underwent ECMO for refractory cardiac arrest. Rates of 90-day survival (hazard ratio [HR]: 2.4, 95% confidence interval [CI]: 1.3-4.4, P = .004) and ST resolution (odds ratio [OR]: 2.5, 95% CI: 1.6-4.1, P = .000) were higher with ticagrelor than with other antiplatelet agents. When analyzed by each agent, patients on ticagrelor had longer survival (HR: 0.4, 95% CI: 0.2-0.8, P = .008) than patients on clopidogrel and more frequent ST resolution than those on clopidogrel or prasugrel (OR: 0.4, 95% CI: 0.2-0.7, P = .002 and OR: 0.4, 95% CI: 0.2-0.7, P = .006). There was no difference in mortality between ticagrelor and prasugrel. CONCLUSIONS: Changes in the treatment of high-risk patients with STEMI over time are in line with changes in treatment guidelines. In these patients, ticagrelor is associated with significantly improved 90-day mortality compared with clopidogrel.

Cervical cancer prevention in Senegal: an International Cooperation Project Report.

BACKGROUND: Cervical cancer is the second most common women's cancer in less developed regions and it is the leading cause of cancer mortality among women in Senegal. Because of the high costs, cervical cancer prevention is very rare in developing countries and it is often based on visual inspection methods. The University of Parma (CUCI)  and the MANI association have developed a cervical cancer screening project addressed to rural Senegal communities. The aim of the project was to disseminate the cytocervical sampling technique among Senegalese nurses and midwives, as a completion to the local visual inspection method. Other objectives were to verify the prevalence of precancerous lesions and to evaluate cervical cancer knowledge and attitudes among women who participated at the screening campaign. INTERVENTIONS: A theoretical and practical training plan on cervical cancer screening was provided to the local health workers at various levels. The screening was performed through a first step visual inspection exam to 203 women, followed by a Pap smear in case of positive outcome. 20 women participated also to a structured interview. RESULTS: The Pap smear material was adequate in all the samples collected where this indicates that the objective to disseminate cervical cancer screening techniques has been achieved.  Of the 203 women involved in the screening project, 68 were tested positive at the first step and 38 of them were submitted to Pap tests. CONCLUSION: The difficulties encountered confirm how Pap tests have overall proved inordinately complex and expensive for developing countries. It seems more sensible to deal first with global health in terms of basic hygienic sanitation, including an educational component in screening programs in order to sensitize women to the risk factors of cervical cancer.

Effects of extracorporeal cardiopulmonary resuscitation on neurological and cardiac outcome after ischaemic refractory cardiac arrest.

BACKGROUND: Extracorporeal cardiopulmonary resuscitation is increasingly recognised as a rescue therapy for refractory cardiac arrest, nevertheless data are scanty about its effects on neurologic and cardiac outcome. The aim of this study is to compare clinical outcome in patients with cardiac arrest of ischaemic origin (i.e. critical coronary plaque during angiography) and return of spontaneous circulation during conventional cardiopulmonary resuscitation vs refractory cardiac arrest patients needing extracorporeal cardiopulmonary resuscitation. Moreover, we tried to identify predictors of survival after successful cardiopulmonary resuscitation. METHODS: We enrolled 148 patients with ischaemic cardiac arrest admitted to our hospital from 2011-2015. We compared clinical characteristics, cardiac arrest features, neurological and echocardiographic data obtained after return of spontaneous circulation (within 24 h, 15 days and six months). RESULTS: Patients in the extracorporeal cardiopulmonary resuscitation group ( n=63, 43%) were younger (59±9 vs 63±8 year-old, p=0.02) with lower incidence of atherosclerosis risk factors than those with conventional cardiopulmonary resuscitation. In the extracorporeal cardiopulmonary resuscitation group, left ventricular ejection fraction was lower than conventional cardiopulmonary resuscitation at early echocardiography (19±16% vs 37±11 p<0.01). Survivors in both groups showed similar left ventricular ejection fraction 15 days and 4-6 months after cardiac arrest (46±8% vs 49±10, 47±11% vs 45±13%, p not significant for both), despite a major extent and duration of cardiac ischaemia in extracorporeal cardiopulmonary resuscitation patients. At multivariate analysis, the total cardiac arrest time was the only independent predictor of survival. CONCLUSIONS: Extracorporeal cardiopulmonary resuscitation patients are younger and have less comorbidities than conventional cardiopulmonary resuscitation, but they have worse survival and lower early left ventricular ejection fraction. Survivors after extracorporeal cardiopulmonary resuscitation have a neurological outcome and recovery of heart function comparable to subjects with return of spontaneous circulation. Total cardiac arrest time is the only predictor of survival after cardiopulmonary resuscitation in both groups.

Effects of Levosimendan on Endothelial Function and Hemodynamics During Weaning From Veno-Arterial Extracorporeal Life Support.

OBJECTIVE: Weaning from veno-arterial extracorporeal life support is challenging. The objective of this trial was to investigate the endothelial and hemodynamic effects of levosimendan in cardiogenic shock patients supported with veno-arterial extracorporeal life support. DESIGN: This was a prospective observational trial. SETTING: Cardiovascular intensive care unit of a large tertiary care university hospital in Monza, Italy. PARTICIPANTS AND INTERVENTIONS: Flow-mediated dilatation of the brachial artery and hemodynamic parameters were assessed in 10 cardiogenic shock patients supported with veno-arterial extracorporeal life support, before and after the infusion of levosimendan. MEASUREMENTS AND RESULTS: Flow-mediated dilatation increased both as absolute value and as a percentage after levosimendan, from 0.10±0.12 to 0.61±0.21 mm (p<0.001) and from 3.2±4.2% to 17.8±10.4% (p<0.001), respectively. Cardiac index increased from 1.93±0.83 to 2.64±0.97 L/min/m2 (p = 0.008) while mixed venous oxygen saturation increased from 66.0% to 71.5% (p = 0.006) and arterial lactate levels decreased from 1.25 to 1.05 mmol/L (p = 0.004) without significant variations in arterial oxygen saturation or hemoglobin levels. This made it possible for clinicians to reduce extracorporeal membrane oxygenation blood flow from 1.92±0.65 to 1.12±0.49 L/min/m2 (p<0.001). CONCLUSION: In conclusion, in the authors' study population of adult cardiogenic shock patients supported with veno-arterial extracorporeal life support, their observations supported the use of levosimendan to improve endothelial function and hemodynamics and facilitate weaning from the extracorporeal support.

Safe ECMO femoral decannulation by placement of inferior vena cava filter via internal jugular vein.

Veno-arterial extracorporeal membrane oxygenation (ECMO) is a lifesaving treatment in patients with cardiogenic shock or cardiac arrest caused by massive pulmonary embolism. In these patients, positioning an inferior vena cava filter is often advisable, especially if deep venous thrombosis is not resolved at the time of the ECMO suspension. Moreover, in ECMO patients, a high incidence of deep venous thrombosis at the site of venous cannulation has been reported, and massive pulmonary embolism following ECMO decannulation has been described. Nonetheless, an inferior vena cava filter cannot be positioned as long as an ECMO cannula is inside the inferior vena cava. Thus, we developed a strategy to allow placement of an inferior vena cava filter through the internal jugular concurrently with the removal of the femoral venous ECMO cannula. In two women supported by veno-arterial ECMO for cardiac arrest secondary to pulmonary embolism, this novel approach allowed for safe ECMO decannulation.

Early vascular complications after percutaneous cannulation for extracorporeal membrane oxygenation for cardiac assist.

BACKGROUND: Extracorporeal membrane oxygenation (VA ECMO) demonstrated an advantage in survival and neurological outcome in patients with cardiogenic shock and, in selected population, in victims of refractory cardiac arrest. The incidence of vascular complications ranges in recent series from 10 to 70% including both early and late complications. The aim of the present study was to determine the incidence of early vascular complications and the effectiveness of the prevention of limb ischemia by the insertion of a catheter for distal perfusion. METHODS: Data from our registry of 100 patients treated with VA ECMO implanted via percutaneous femoral approach for cardiogenic shock or refractory cardiac arrest were analyzed. If the leg perfusion was inadequate, an additional 7-9 Fr percutaneous catheter distal to the ECMO arterial cannula was placed into the femoral artery to prevent limb ischemia. RESULTS: Thirty-five patients had early vascular complications. Thirty patients with early ischemia were cannulated with a small reperfusion cannula to obtain antegrade perfusion of the limb. Twenty-six had an effective reperfusion. Seven patients developed a compartment syndrome of the leg requiring urgent fasciotomy that led to clinical improvement and recovery in five, while the other two patients progressed to irreversible ischemia requiring amputation of the limb. CONCLUSION: The majority of ischemic episodes were resolved with the insertion of a distal perfusion catheter. We did not observe any mortal vascular complication, nor any of the observed complications was related to increased mortality.

Apnea test during brain death assessment in mechanically ventilated and ECMO patients.

PURPOSE: To evaluate the feasibility and efficacy of an apnea test (AT) technique that combines the application of positive end expiratory pressure (PEEP) with subsequent pulmonary recruitment in a large cohort of brain-dead patients. METHODS: This study was a retrospective analysis of prospectively collected data on brain-dead patients admitted to our institution (Hospital San Gerardo, Monza, Italy) between January 2010 and December 2014. The rate of aborted apnea tests (ATs), occurrence of complications (i.e., pneumothorax, cardiac arrhythmias, cardiac arrest, and severe hypoxia, defined as PaO2 < 40 mmHg), ventilator settings, hemodynamics, and blood gas analyses were evaluated. Subgroup analysis was performed, with patients classified into veno-arterial extracorporeal membrane oxygenation (ECMO) or non-ECMO groups, and into hypoxic (i.e., baseline PaO2/FiO2 < 200 mmHg) and non-hypoxic (i.e., baseline PaO2/FiO2 > 200 mmHg) groups. RESULTS: In total, 169 consecutive patients including 25 on ECMO were included in the study. No AT abortion nor severe complications were detected. The AT was completed in all patients. Fluid boluses and increases or initiation of vasoactive drugs were required in less than 10 and 3% of the AT procedures, respectively. No clinically meaningful alteration in hemodynamics was recorded. Severe hypoxia occurred during 7 (2.4%) and 4 (8%) of the ATs performed in non-ECMO and ECMO patients, respectively (p = 0.063), and it occurred more frequently in hypoxic patients than in non-hypoxic patients (11.1 vs. 4.8%, respectively; p = 0.002). CONCLUSIONS: In a large cohort of consecutive patients, including the largest patient population on ECMO reported to date, our AT technique that combines the application of PEEP with subsequent pulmonary recruitment proved to be feasible and safe.

Favourable survival of in-hospital compared to out-of-hospital refractory cardiac arrest patients treated with extracorporeal membrane oxygenation: an Italian tertiary care centre experience.

OBJECTIVE: Extracorporeal membrane oxygenation (ECMO) support has been suggested to improve the survival rate in patients with refractory in- and out-of-hospital cardiac arrest (IHCA and OHCA). The aim of our study is to report our experience with ECMO in these patients. DESIGN: Retrospective, single-centre, observational study. PATIENTS: From January 2006 to February 2011 we studied 42 patients (31 males) with refractory cardiac arrest. MEASUREMENT AND MAIN RESULTS: ECMO implantation was successful in 38 (90%) of the 42 patients. ECMO support was positioned: three times (8%) in the operating room, six (16%) in the cardiac surgery intensive care unit, 21 (55%) in the emergency room, five (13%) in the catheterisation laboratory and three (8%) in the general ward. A total of 14 IHCA (58%) and three OHCA (16%) patients were weaned from ECMO (p<0.05). Eleven IHCA (46%) and one OHCA (5%, p<0.05) patients were discharged from intensive care unit (ICU). Among IHCA patients, 10 were alive at 6 months, nine of whom (38%) with good neurological outcome. Among OHCA patients weaned from ECMO, one was alive at 6 months with good neurological outcome (5%, p<0.05 vs. IHCA). CONCLUSIONS: ECMO support should be considered as a resuscitation alternative in selected patients. More specifically, patients with witnessed IHCA benefit more from ECMO treatment compared to those who experience an out-of-hospital cardiac arrest.

Percutaneous left-heart decompression during extracorporeal membrane oxygenation: an alternative to surgical and transeptal venting in adult patients.

Extracorporeal membrane oxygenation (ECMO) is often applied for acute cardiorespiratory failure. Left ventricular distension can compromise recovery of the failing heart. To overcome this complication, we describe a new technique to decompress the left heart through the insertion of a venting cannula in the pulmonary artery. A 43-year-old woman was connected to ECMO for refractory cardiogenic shock after left pneumonia and severe sepsis. Transesophageal echocardiography (TEE) revealed a large intraventricular clot. A 15F venous cannula was placed percutaneously in the pulmonary artery and connected to the venous limb of the ECMO circuit to decompress the left heart, and to prevent left ventricular ejection and potential embolization. After myocardial recovery, when the thrombus was judged as stable, the patient was weaned, and ECMO was removed on day 16. The patient was discharged from the cardiac surgery intensive care unit on day 30 and subsequently had an uneventful recovery. This new percutaneous approach represent a feasible and effective method to vent the left heart during ECMO, when it becomes necessary to reduce wall tension or to prevent ejection.

Role of absolute lung volume to assess alveolar recruitment in acute respiratory distress syndrome patients.

OBJECTIVE: It is commonly assumed that lung volume at zero end-expiratory pressure (functional residual capacity) is not affected by positive end-expiratory pressure (PEEP) even in presence of alveolar recruitment, and it is often ignored when measuring lung recruitment by pressure-volume curves. Aim of the study was to investigate the effect of PEEP on functional residual capacity, and quantify the error of considering equal functional residual capacity in measuring alveolar recruitment. DESIGN: Interventional human study. SETTING: A 10-bed general intensive care unit in a university hospital. PATIENTS: Ten sedated, curarized, mechanically ventilated acute respiratory distress syndrome patients. INTERVENTIONS: Three levels of PEEP (5, 10, and 15 cm H2O), were randomly applied, for 1 hr each. MEASUREMENTS AND MAIN RESULTS: At each PEEP we obtained a pressure-volume curve, the volume expired from PEEP to zero pressure (PEEP related lung volume) and functional residual capacity by helium dilution method. Functional residual capacity increased at increasing PEEP levels. Functional residual capacity was 507 +/- 292, 607 +/- 311, and 681 +/- 312 ml (p < .05), respectively, at PEEP 5, 10, and 15 cm H2O. Pressure-volume curves were aligned starting from PEEP related lung volume (relative volume method) or from end-expiratory lung volume at PEEP (absolute volume method). Recruitment was measured as vertical distance of pressure-volume curves at 20 cm H2O airway pressure. The relative volume method led to underestimation of recruitment (43 +/- 28% and 35 +/- 18 %, respectively, at PEEP 10 and 15). CONCLUSIONS: Functional residual capacity is affected by PEEP. Ignoring this effect leads to relevant underestimation of alveolar recruitment as measure by pressure-volume curve displacement.

Extracorporeal membrane oxygenation to support adult patients with cardiac failure: predictive factors of 30-day mortality.

Adult patients supported on extracorporeal membrane oxygenation (ECMO) are very sick and many complications are often present in each single patient; therefore, it is not always easy to find some risk factors that can predict the early outcome. This retrospective study reports our experience in ECMO support treatment in adult cardiac patients suffering from cardiac failure (CF) in which one or more predictive factors of 30-day mortality were analyzed. Between January 2002 and August 2009, 42 consecutive adult cardiac patients with cardiogenic shock (mean age 64.3+/-11.3 years) were supported on ECMO for >2 days. They were divided into patients who had a survival <30 days (n=20) and patients who survived >30 days (n=22). Twenty-nine patients (69%) survived on ECMO. Sixteen patients were discharged with a survival rate of 38.1%. The overall mean ECMO duration was 7.9+/-5.3 days. The following variables were significantly different between the two groups: number of platelets and packed red blood cells (PRBCs) transfused per day during ECMO (P=0.002 and P=0.003), blood lactate levels 48 h and 72 h after the initiation of ECMO (P=0.01 and P=0.04), indexed blood flow after 48 h and 72 h (P=0.01 and P<0.0001), liver failure (P=0.001) and multiorgan failure (P=0.002). Stepwise logistic regression identified that blood lactate levels at 48 h and number of PRBCs transfused were associated with 30-day mortality [P=0.019, odds ratio (OR) =2.16; 95% confidence interval (CI)=1.13-4.14 and P=0.008, OR=1.08; 95% CI=1.02-1.14, respectively]. The predicted probability of mortality would be 52% when blood lactate levels are >3 mmol/l after 48 h. The blood lactate level at 48 h and PRBCs transfused per day can be considered as important parameters to predict the mortality in adult cardiac patients supported by ECMO for CF.

Extracorporeal membrane oxygenation with a poly-methylpentene oxygenator (Quadrox D). The experience of a single Italian centre in adult patients with refractory cardiogenic shock.

Although microporous polypropylene hollow fiber oxygenators are standard devices used for extracorporeal membrane oxygenation (ECMO), they have limitations such as development of plasma leakage. Poly-methylpentene (PMP) is a new material used for the last generation of oxygenators. We reviewed our experience with a new PMP oxygenator (Quadrox D) and a centrifugal pump (RotaFlow) used to support adult patients with refractory cardiogenic shock. Between January 2000 and April 2007, 25 patients required ECMO for primary or postcardiotomy cardiogenic shock. Eighteen patients were analyzed [mean age 60.2 years; 11 (61%) men; 7 (39%) women]. Nine patients (50%) suffered primary cardiogenic shock. Cardiopulmonary resuscitation was applied in 11 patients (61%) with a mean duration time of 31.5 minutes. Mean ECMO duration time was 7.1 +/- 6.3 days (range, 1-27 days). Intra-aortic balloon pump was used in 13 patients (72.2%) with a mean duration time of 7.7 +/- 5 (range, 2-17 days). Twelve patients (66.7%) survived on ECMO and five patients (27.8%) were discharged. Our results indicate the PMP oxygenator and the centrifugal pump provided acceptable results in terms of surviving on ECMO and discharge. Patients with an initial catastrophic hemodynamic status could benefit by means of a rapid institution of ECMO with PMP oxygenators.

Measurement of pulmonary edema in patients with acute respiratory distress syndrome.

OBJECTIVE: We measured pulmonary edema by thermal indocyanine green-dye double-dilution technique and quantitative computed tomography (CT) in patients with acute respiratory distress syndrome and compared the two techniques. DESIGN AND SETTING: Prospective human study in a university hospital. PATIENTS: Fourteen mechanically ventilated patients with acute respiratory distress syndrome (nine primary; nine with intubation <7 days). INTERVENTIONS: All patients underwent a spiral CT of the thorax. We measured pulmonary thermal volume (PTV) and its components, extravascular lung water and pulmonary blood volume, with an integrated fiberoptic monitoring system (COLD Z-021). MEASUREMENTS AND RESULTS: PTV was tightly correlated with lung weight (LW) measured by CT (PTV = 0.6875 * LW(CT) + 292.77; correlation coefficient = 0.91; p < .0001; bias -11 +/- 8 %). Neither etiology of acute respiratory distress syndrome (primary vs. secondary) nor days of intubation affected the accuracy of thermal dye dilution in comparison with CT. There was no correlation between the extravascular lung water (12.3 +/- 3.4 mL/kg) and CT distribution of lung tissue compartments. Extravascular lung water and pulmonary blood volume showed good reproducibility in 32 pairs of thermal dye dilution measurements. CONCLUSIONS: Measurements of lung edema by thermal indocyanine green-dye double-dilution method show good correlation with those by quantitative computed tomography and good reproducibility in patients with acute respiratory distress syndrome.

Lung volume in mechanically ventilated patients: measurement by simplified helium dilution compared to quantitative CT scan.

OBJECTIVE: We describe a simplified helium dilution technique to measure end-expiratory lung volume (EELV) in mechanically ventilated patients. We assessed both its accuracy in comparison with quantitative computerized tomography (CT) and its precision. DESIGN AND SETTING: Prospective human study. PATIENTS: Twenty-one mechanically ventilated ALI/ARDS patients. INTERVENTIONS: All patients underwent a spiral CT scan of the thorax during an end-expiratory occlusion. From the CT scan we computed the gas volume of the lungs (EELVCT). Within a few minutes, a rebreathing bag, containing a known amount of helium, was connected to the endotracheal tube, and the gas mixture diluted in the patient's lungs by delivering at least ten large tidal volumes. From the final helium concentration, EELV could be calculated by a standard formula (EELVHe). MEASUREMENT AND RESULTS: The results obtained by the two techniques showed a good correlation (EELVHe=208+0.858xEELV(CT), r=0.941; P<0.001). Bias between the two techniques was 32.5+/-202.8 ml (95% limits of agreement were -373 ml and +438 ml), with a mean absolute difference of 15%. The amount of pathological tissue did not affect the difference between the two techniques, while the amount of hyperinflated tissue did. Bias between two repeated helium EELV measurements was -24+/-83 ml (95% limits of agreement were -191 ml and +141 ml), with a mean absolute difference of 6.3%. CONCLUSIONS: The proposed helium dilution technique is simple and reproducible. The negligible bias and the acceptable level of agreement support its use as a practical alternative to CT for measuring EELV in mechanically ventilated ARDS patients.

Sigh improves gas exchange and lung volume in patients with acute respiratory distress syndrome undergoing pressure support ventilation.

BACKGROUND: The aim of our study was to assess the effect of periodic hyperinflations (sighs) during pressure support ventilation (PSV) on lung volume, gas exchange, and respiratory pattern in patients with early acute respiratory distress syndrome (ARDS). METHODS: Thirteen patients undergoing PSV were enrolled. The study comprised 3 steps: baseline 1, sigh, and baseline 2, of 1 h each. During baseline 1 and baseline 2, patients underwent PSV. Sighs were administered once per minute by adding to baseline PSV a 3- to 5-s continuous positive airway pressure (CPAP) period, set at a level 20% higher than the peak airway pressure of the PSV breaths or at least 35 cm H2O. Mean airway pressure was kept constant by reducing the positive end-expiratory pressure (PEEP) during the sigh period as required. At the end of each study period, arterial blood gas tensions, air flow and pressures traces, end-expiratory lung volume (EELV), compliance of respiratory system (Crs), and ventilatory parameters were recorded. RESULTS: Pao2 improved (P < 0.001) from baseline 1 (91.4 +/- 27.4 mmHg) to sigh (133 +/- 42.5 mmHg), without changes of Paco2. EELV increased (P < 0.01) from baseline 1 (1,242 +/- 507 ml) to sigh (1,377 +/- 484 ml). Crs improved (P < 0.01) from baseline 1 (40.2 +/- 12.5 ml/cm H2O) to sigh (45.1 +/- 15.3 ml/cm H2O). Tidal volume of pressure-supported breaths and the airway occlusion pressure (P0.1) decreased (P < 0.01) during the sigh period. There were no significant differences between baselines 1 and 2 for all parameters. CONCLUSIONS: The addition of 1 sigh per minute during PSV in patients with early ARDS improved gas exchange and lung volume and decreased the respiratory drive.