Biomedical subjects
Publications and source records attributed to Davide Chiumello.
Computed tomography has completely changed the views and interpretation of ARDS, opening a new era in our understanding of the physiological, pathological and clinical aspects of this syndrome. In this brief review we will emphasize the most relevant new knowledge achieved using CT scanning and we will briefly discuss its clinical use in ARDS patients.
OBJECTIVE: Intraabdominal hypertension is associated with significant morbidity and mortality in surgical and trauma patients. The aim of this study was to assess, in a mixed population of critically ill patients, whether intraabdominal pressure at admission was an independent predictor for mortality and to evaluate the effects of intraabdominal hypertension on organ functions. DESIGN: Multiple-center, prospective epidemiologic study. SETTING: Fourteen intensive care units in six countries. PATIENTS: A total of 265 consecutive patients admitted for >24 hrs during the 4-wk study period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Intraabdominal pressure was measured twice daily via the bladder. Data recorded on admission were the patient demographics with Simplified Acute Physiology Score II, Acute Physiology and Chronic Health Evaluation II score, and type of admission; during intensive care stay, Sepsis-Related Organ Failure Assessment score and intraabdominal pressure were measured daily together with fluid balance. Nonsurvivors had a significantly higher mean intraabdominal pressure on admission than survivors: 11.4 +/- 4.8 vs. 9.5 +/- 4.8 mm Hg. Independent predictors for mortality were age (odds ratio, 1.04; 95% confidence interval, 1.01-1.06; p = .003), Acute Physiology and Chronic Health Evaluation II score (odds ratio, 1.1; 95% confidence interval, 1.05-1.15; p < .0001), type of intensive care unit admission (odds ratio, 2.5 medical vs. surgical; 95% confidence interval, 1.24-5.16; p = .01), and the presence of liver dysfunction (odds ratio, 2.5; 95% confidence interval, 1.06-5.8; p = .04). The occurrence of intraabdominal hypertension during the intensive care unit stay was also an independent predictor of mortality (relative risk, 1.85; 95% confidence interval, 1.12-3.06; p = .01). Patients with intraabdominal hypertension at admission had significantly higher Sepsis-Related Organ Failure Assessment scores during the intensive care unit stay than patients without intraabdominal hypertension. CONCLUSIONS: Intraabdominal hypertension on admission was associated with severe organ dysfunction during the intensive care unit stay. The mean intraabdominal pressure on admission was not an independent risk factor for mortality; however, the occurrence of intraabdominal hypertension during the intensive care unit stay was an independent outcome predictor.
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INTRODUCTION: In order to improve the efficiency of heat moisture exchangers (HMEs), new hybrid humidifiers (active HMEs) that add water and heat to HMEs have been developed. In this study we evaluated the efficiency, both in vitro and in vivo, of a new active HME (the Performer; StarMed, Mirandola, Italy) as compared with that of existing HMEs (Hygroster and Hygrobac; Mallinckrodt, Mirandola, Italy). METHODS: We tested the efficiency by measuring the temperature and absolute humidity (AH) in vitro using a test lung ventilated at three levels of minute ventilation (5, 10 and 15 l/min) and at two tidal volumes (0.5 and 1 l), and in vivo in 42 patients with acute lung injury (arterial oxygen tension/fractional inspired oxygen ratio 283 +/- 72 mmHg). We also evaluated the efficiency in vivo after 12 hours. RESULTS: In vitro, passive Performer and Hygrobac had higher airway temperature and AH (29.2 +/- 0.7 degrees C and 29.2 +/- 0.5 degrees C, [P < 0.05]; AH: 28.9 +/- 1.6 mgH2O/l and 28.1 +/- 0.8 mgH2O/l, [P < 0.05]) than did Hygroster (airway temperature: 28.1 +/- 0.3 degrees C [P < 0.05]; AH: 27 +/- 1.2 mgH2O/l [P < 0.05]). Both devices suffered a loss of efficiency at the highest minute ventilation and tidal volume, and at the lowest minute ventilation. Active Performer had higher airway temperature and AH (31.9 +/- 0.3 degrees C and 34.3 +/- 0.6 mgH2O/l; [P < 0.05]) than did Hygrobac and Hygroster, and was not influenced by minute ventilation or tidal volume. In vivo, the efficiency of passive Performer was similar to that of Hygrobac but better than Hygroster, whereas Active Performer was better than both. The active Performer exhibited good efficiency when used for up to 12 hours in vivo. CONCLUSION: This study showed that active Performer may provide adequate conditioning of inspired gases, both as a passive and as an active device.
The importance of chest wall elastance in characterizing acute lung injury/acute respiratory distress syndrome patients and in setting mechanical ventilation is increasingly recognized. Nearly 30% of patients admitted to a general intensive care unit have an abnormal high intra-abdominal pressure (due to ascites, bowel edema, ileus), which leads to an increase in the chest wall elastance. At a given applied airway pressure, the pleural pressure increases according to (in the static condition) the equation: pleural pressure = airway pressure x (chest wall elastance/total respiratory system elastance). Consequently, for a given applied pressure, the increase in pleural pressure implies a decrease in transpulmonary pressure (airway pressure - pleural pressure), which is the distending force of the lung, implies a decrease of the strain and of ventilator-induced lung injury, implies the need to use a higher airway pressure during the recruitment maneuvers to reach a sufficient transpulmonary opening pressure, implies hemodynamic risk due to the reductions in venous return and heart size, and implies a possible increase of lung edema, partially due to the reduced edema clearance. It is always important in the most critically ill patients to assess the intra-abdominal pressure and the chest wall elastance.
OBJECTIVE: Although intra-abdominal hypertension (IAH) can cause dysfunction of several organs and raise mortality, little information is available on the incidence and risk factors for IAH in critically ill patients. This study assessed the prevalence of IAH and its risk factors in a mixed population of intensive care patients. DESIGN: A multicentre, prospective 1-day point-prevalence epidemiological study conducted in 13 ICUs of six countries. INTERVENTIONS: None. PATIENTS: Ninety-seven patients admitted for more than 24 h to one of the ICUs during the 1-day study period. METHODS: Intra-abdominal pressure (IAP) was measured four times (every 6 h) by the bladder pressure method. Data included the demographics, medical or surgical type of admission, SOFA score, etiological factors such as abdominal surgery, haemoperitoneum, abdominal infection, massive fluid resuscitation, and ileus and predisposing conditions such as hypothermia, acidosis, polytransfusion, coagulopathy, sepsis, liver dysfunction, pneumonia and bacteraemia. RESULTS: We enrolled 97 patients, mean age 64+/-15 years, 57 (59%) medical and 40 (41%) surgical admission, SOFA score of 6.5+/-4.0. Mean IAP was 9.8+/-4.7 mmHg. The prevalence of IAH (defined as IAP 12 mmHg or more) was 50.5 and 8.2% had abdominal compartment syndrome (defined as IAP 20 mmHg or more). The only risk factor significantly associated with IAH was the body mass index, while massive fluid resuscitation, renal and coagulation impairment were at limit of significance. CONCLUSION: Although we found a quite high prevalence of IAH, no risk factors were reliably associated with IAH; consequently, to get valid information about IAH, IAP needs to be measured.
BACKGROUND: Noninvasive positive pressure ventilation (NPPV) with a facemask (FM) is effective in patients with acute exacerbation of their chronic obstructive pulmonary disease. Whether it is feasible to treat these patients with NPPV delivered by a helmet is not known. METHODS: Over a 4-month period, the authors studied 33 chronic obstructive pulmonary disease patients with acute exacerbation who were admitted to four intensive care units and treated with helmet NPPV. The patients were compared with 33 historical controls treated with FM NPPV, matched for simplified acute physiologic score (SAPS II), age, PaCO2, pH, and PaO2:fractional inspired oxygen tension. The primary endpoints were the feasibility of the technique, improvement of gas exchange, and need for intubation. RESULTS: The baseline characteristics of the two groups were similar. Ten patients in the helmet group and 14 in the FM group (P = 0.22) were intubated. In the helmet group, no patients were unable to tolerate NPPV, whereas five patients required intubation in the FM group (P = 0.047). After 1 h of treatment, both groups had a significant reduction of PaCO2 with improvement of pH; PaCO2 decreased less in the helmet group (P = 0.01). On discontinuing support, PaCO2 was higher (P = 0.002) and pH lower (P = 0.02) in the helmet group than in the control group. One patient in the helmet group, and 12 in the FM group, developed complications related to NPPV (P < 0.001). Length of intensive care unit stay, intensive care unit, and hospital mortality were similar in both groups. CONCLUSIONS: Helmet NPPV is feasible and can be used to treat chronic obstructive pulmonary disease patients with acute exacerbation, but it does not improve carbon dioxide elimination as efficiently as does FM NPPV.
A 76-year-old man underwent an emergency laparotoray for a ruptured abdominal aortic ancurysm After a few days he presented ischemia of the left side of the colon and subsequently atrial fibrillation developed that was treated with Amiodarone. After an intravascular loading dose of 300 mg, he received a maintenance dose of 600 mg daily through a central line access. After 28 days of intravascular drug therapy, a chest X-ray showed a high attenuation homogeneous image in the right part of the mediastinum. A contrast enhanced thoracic and abdominal computed tomography scan showed: a high attenuation intravascular mass in the superior vena cava around the catheter. The catheter was substituted but the intravascular mass remained. The Amiodarone was then given by mouth. The mass spontaneously decreased its size and after three months completely disappeared Due to high iodine content, any deposition of Amiodarone can be detected by a radiological study as a high attenuation image. After reviewing all the drugs infused through the catheter, we did not find any other drugs that contain iodine or other material that could justify the chest X-ray image. We hypothesized that this intravascular mass was due to a deposition of the Amiodarone during the infusion in the central line
In the last several years, we definitely learned that the acute respiratory distress syndrome lung is small, nonhomogeneous, and that mechanical ventilation in this baby lung may cause physical damage as well as inflammatory reaction. The clinical benefit of the gentle lung treatment, based on a decrease of global/regional stress and strain into the lung, has been finally proved. However, we forgot the importance of lung perfusion and its distribution in this syndrome and, besides a low tidal volume, we still do not know how to handle the other variables of mechanical ventilation. Measurements of variables as transpulmonary pressure and end expiratory lung volume, for a rational setting of mechanical ventilation, should be introduced in routine clinical practice.
OBJECTIVE: This bench and human study compared large and small helmets with face mask (FM) for delivery of noninvasive positive pressure ventilation. DESIGN: A lung simulator was employed, and the human study involved six healthy subjects. We evaluated a continuous high-flow (CPAPHF), low flow (CPAPLF), ventilator (CPAPVENT) CPAP, and pressure support ventilation (PSV 10 and 20 cmH2O). In the human study we used CPAPHF, CPAPVENT, and PSV 5 cmH2O. PEEP was 5 cmH2O. MEASUREMENTS: In the bench study during CPAP we measured the negative airway pressure time product (areaCPAP), i.e., the area of airway pressure (Paw) under PEEP and during PSV the pressure airway time product (areaPSV), i.e., the area of Paw from onset to end of inspiratory flow. In the human study we measured the breathing pattern and work of breathing (WOB). RESULTS: In the bench study during CPAPLF the helmets had a lower areaCPAP than the FM, while during CPAPHF the three interfaces had similar areaCPAP. Using CPAPVENT and PSV the FM reduced areaCPAP and increased areaPSV compared to helmets. At 20 cmH2O of PSV using helmets areaPSV was similar to that obtained at 10 cmH2O of PSV using the FM. In human study using CPAPHF and CPAPVENT the tree interfaces had similar effects on breathing pattern and WOB, while using PSV the FM reduced WOB more than helmets. CONCLUSIONS: During CPAPLF helmets were more efficient than FM, while during CPAPHF the three interfaces were comparable. Using CPAPVENT and PSV, FM was more efficient than helmets
Non-invasive positive pressure ventilation is increasingly used as a first-line treatment for respiratory failure. Non-invasive positive pressure ventilation can reduce the complications of endotracheal intubation such as barotrauma, nosocomial infections and the need for sedation. Non-invasive positive pressure ventilation has been shown to reduce the rate of endotracheal intubation in acute cardiogenic pulmonary oedema (27%), in chronic obstructive pulmonary disease (21%), and in acute respiratory failure (17%). Non-invasive positive pressure ventilation can be successfully delivered in the emergency department or in the general ward. However, the criteria for interrupting non-invasive positive pressure ventilation must be stricter (i.e. failure to improve gas exchange within 30 min) than in the general ward. One of the main reasons for the failure of non-invasive positive pressure ventilation lies in the technical problems caused by the face mask. We recently developed a new interface, the 'helmet', to deliver non-invasive positive pressure ventilation. When using the helmet instead of a face mask an increase of 10 cm H(2)O of pressure support and a fast pressurization rate are recommended. In a lung model and in healthy individuals the helmet reduced inspiratory effort. In hypoxemic patients the helmet reduced the intubation rate and the incidence of face mask-related complications. We believe that the helmet can extend the application of non-invasive positive pressure ventilation in different categories of patients with respiratory failure.
OBJECTIVES: To review the physiologic approach to setting mechanical ventilation in acute lung injury/acute respiratory distress syndrome. DATA SOURCES: MEDLINE search from 1979 to the present. DATA SELECTION: Personal selection of some articles we believe relevant for understanding acute lung injury/acute respiratory distress syndrome physiopathology and its physiologic management. DATA SUMMARY: Knowing the underlying pathology is key to estimating the potential for recruitment. The potential for recruitment is rather low when the consolidation of pulmonary units exceeds collapse, as in diffuse pneumonia. In contrast, when pulmonary unit collapse exceeds consolidation, as in acute lung injury/acute respiratory distress syndrome from extrapulmonary origin, the potential for recruitment may be high. To exploit the potential for recruitment, a transpulmonary pressure greater than the opening pressure must be applied to the lung. To do so, chest wall elastance must be measured or estimated. To avoid collapse after recruitment, a positive end-expiratory pressure greater than the compressive forces operating on the lung and an alveolar ventilation sufficient to prevent absorption atelectasis must be provided. Indeed, avoidance of stretch (low airway plateau pressure) and prevention of cyclic collapse and reopening (adequate positive end-expiratory pressure and alveolar ventilation) are the physiologic cornerstones of mechanical ventilation in acute lung injury/acute respiratory distress syndrome. When considering all the randomized clinical trials reported so far, it is tempting to speculate that transpulmonary pressure and stresses, rather than tidal volume per se, are the key factors that may have an impact on mortality. CONCLUSIONS: The majority of physiologic, experimental, and clinical trial data converge on one simple concept: treat the lung gently.
OBJECTIVE: With many mechanical ventilators, it is possible to modify the time to reach the selected airway pressure and the criteria for cycling off the inflation during pressure support ventilation. This study evaluated the effect of different inspiratory rise time and cycling off criteria on breathing pattern and work of breathing. DESIGN: Clinical study. SETTING: University laboratory. PATIENTS: Ten intubated patients recovering from acute lung injury (PaO2/FiO2 245 +/- 26 torr, positive end-expiratory pressure 9 +/- 3 cm H2O). INTERVENTIONS: We studied two inspiratory rise time criteria (shortest and longest, 0% and 40% of the breath cycle time) and two cycling off criteria (lowest and highest, 5% and 40% of the peak inspiratory flow) at 5 and 15 cm H2O of pressure support. Respiratory rate, tidal volume, and inspiratory and expiratory work of breathing (WOBI and WOBE) were measured. MEASUREMENTS AND MAIN RESULTS: At both levels of pressure support ventilation, the shortest inspiratory rise time significantly reduced the WOBI from 0.77 +/- 0.32 to 0.56 +/- 0.23 J/L and from 0.24 +/- 0.28 to 0.08 +/- 0.09 J/L without affecting respiratory rate or tidal volume. At 15 cm H2O of pressure support ventilation, the lowest cycling off criteria significantly reduced respiratory rate from 24.9 +/- 12.1 to 21.5 +/- 12.7 beats/min and increased tidal volume from 0.51 +/- 0.17 to 0.60 +/- 0.26 L. At both levels of pressure support ventilation, the modification of cycling off criteria did not influence WOBI and WOBE. CONCLUSIONS: Our results suggest that in patients recovering from acute lung injury during pressure support ventilation, a) the shortest inspiratory rise time reduces the WOBI; and b) at 15 cm H2O of pressure support ventilation, the lowest cycling off criteria reduces the respiratory rate and increases the tidal volume without modifying the WOBI and WOBE. Modifications of inspiratory rise time and cycling off criteria must be carefully adjusted during pressure support ventilation.
OBJECTIVE: To determine whether gas exchange improvement in response to the prone position is associated with an improved outcome in acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). DESIGN: Retrospective analysis of patients in the pronation arm of a controlled randomized trial on prone positioning and patients enrolled in a previous pilot study of the prone position. SETTING: Twenty-eight Italian and two Swiss intensive care units. PATIENTS: We studied 225 patients meeting the criteria for ALI or ARDS. INTERVENTIONS: Patients were in prone position for 10 days for 6 hrs/day if they met ALI/ARDS criteria when assessed each morning. Respiratory variables were recorded before and after 6 hrs of pronation with unchanged ventilatory settings. MEASUREMENTS AND MAIN RESULTS: We measured arterial blood gas alterations to the first pronation and the 28-day mortality rate. The independent risk factors for death in the general population were the Pao2/Fio2 ratio (odds ratio, 0.992; confidence interval, 0.986-0.998), the minute ventilation/Paco2 ratio (odds ratio, 1.003; confidence interval, 1.000-1.006), and the concentration of plasma creatinine (odds ratio, 1.385; confidence interval, 1.116-1.720). Pao2 responders (defined as the patients who increased their Pao2/Fio2 by > or =20 mm Hg, 150 patients, mean increase of 100.6 +/- 61.6 mm Hg [13.4 +/- 8.2 kPa]) had an outcome similar to the nonresponders (59 patients, mean decrease -6.3 +/- 23.7 mm Hg [-0.8 +/- 3.2 kPa]; mortality rate 44% and 46%, respectively; relative risk, 1.04; confidence interval, 0.74-1.45, p =.65). The Paco2 responders (defined as patients whose Paco2 decreased by > or =1 mm Hg, 94 patients, mean decrease -6.0 +/- 6 mm Hg [-0.8 +/- 0.8 kPa]) had an improved survival when compared with nonresponders (115 patients, mean increase 6 +/- 6 mm Hg [0.8 +/- 0.8 kPa]; mortality rate 35.1% and 52.2%, respectively; relative risk, 1.48; confidence interval, 1.07-2.05, p =.01). CONCLUSION: ALI/ARDS patients who respond to prone positioning with reduction of their Paco2 show an increased survival at 28 days. Improved efficiency of alveolar ventilation (decreased physiologic deadspace ratio) is an important marker of patients who will survive acute respiratory failure.
Interventions aimed at recruiting the lung of patients with acute respiratory distress syndrome (ARDS) are not uniformly effective. Because the prone position increases homogeneity of inflation of the lung, we reasoned that it might enhance its potential for recruitment. We ventilated 10 patients with early ARDS (PaO2/FIO2, 121 +/- 46 mm Hg; positive end-expiratory pressure, 14 +/- 3 cm H2O) in supine and prone, with and without the addition of three consecutive "sighs" per minute to recruit the lung. Inspired oxygen fraction, positive end-expiratory pressure, and minute ventilation were kept constant. Sighs increased PaO2 in both supine and prone (p < 0.01). The highest values of PaO2 (192 +/- 41 mm Hg) and end-expiratory lung volume (1840 +/- 790 ml) occurred with the addition of sighs in prone and remained significantly elevated 1 hour after discontinuation of the sighs. The increase in PaO2 associated with the sighs, both in supine and prone, correlated linearly with the respective increase of end-expiratory lung volume (r = 0.82, p < 0.001). We conclude that adding a recruitment maneuver such as cyclical sighs during ventilation in the prone position may provide optimal lung recruitment in the early stage of ARDS.
Three major determinants of lung injury associated with mechanical ventilation have been clearly identified: high pressure/high volume, the shear forces caused by intratidal collapse and decollapse leading to barotrauma/volotrauma/biotrauma. The lung protective strategy aims to reduce the impact of all three determinants. A groundbreaking study showed that reduced tidal volume is less dangerous than high tidal volume, but the researchers did not apply "full" lung protective strategy and did not take into account the shear forces. "Full" protective lung strategy was tested in only one study and in a limited number of patients. Several physiologic studies strongly suggest the advantages of the lung protective strategy.