The semi-seated position slightly reduces the effort to breathe during difficult weaning.

PURPOSE: The influence of posture on breathing effort in patients with difficult weaning is unknown. We hypothesized that posture could modulate the breathing effort in difficult-to-wean patients. METHODS: A prospective, crossover, physiologic study was performed in 24 intubated patients breathing with pressure support who had already failed a spontaneous breathing trial or an extubation episode. Their median duration of mechanical ventilation before measurements was 25 days. Breathing pattern, occlusion pressure (P (0.1)), intrinsic PEEP (PEEP(i)), and inspiratory muscle effort evaluated by the pressure-time product of the respiratory muscles and the work of breathing were measured during three postures: the seated position in bed (90°LD), simulating the position in a chair, the semi-seated (45°), and the supine (0°) positions consecutively applied in a random order. A comfort score was obtained in 17 cooperative patients. The influence of position on chest wall compliance was measured in another group of 11 sedated patients. RESULTS: The 45° position was associated with the lowest levels of effort (p ≤ 0.01) and occlusion pressure (p < 0.05), and tended to be more often comfortable. Respiratory effort was the lowest at 45° in 18/24 patients. PEEP(i) and PEEP(i)-related work were slightly higher in the supine position (p ≤ 0.01), whereas respiratory effort, heart rate, and P (0.1) values were increased in the seated position (p < 0.05). CONCLUSION: A 45° position helps to unload the respiratory muscles, moderately reduces PEEP(i), and is often considered as comfortable. The semi-seated position may help the weaning process in ventilator-dependent patients.

Successful application of helmet non-invasive ventilation in a parturient with acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is an important cause of morbidity and mortality during pregnancy. The case of a twin pregnant woman in her 28th week who developed infection-related ARDS, undergoing a cesarean section for premature membrane rupture is described. It was performed epidural anaesthesia and helmet non-invasive ventilation (NIV) during the postoperative period. The combination of epidural anesthesia with NIV helped to restore physiological gas-exchange and to prevent common complications associated with a more invasive approach.

What has been learnt from P/V curves in patients with acute lung injury/acute respiratory distress syndrome.

Mechanical impairment of the respiratory system was recognised soon after the description of acute respiratory distress syndrome. The analysis of the pressure/volume (P/V) curve of the respiratory system contributed a lot to the understanding of the pathophysiology of acute lung injury and formed the basis for lung protection. The lower and upper inflection points were regarded as points of interest to avoid cyclic derecruitment and overdistension and to optimise ventilatory settings. However, because of the heterogeneity of lung injury, reducing the mechanical properties of the whole respiratory system to a single curve is a schematic approach, which makes interpretation difficult. New data suggest that alveolar re-inflation occurs along the whole P/V curve that can, therefore, be considered as a recruitment curve. The lower inflection point has no relationship with alveolar opening and closure and does not indicate the positive end-expiratory pressure needed to prevent alveolar collapse. The shape of the P/V curve gives information about the extension and the homogeneity of lung injury, indicating the possibility of lung recruitment. The upper inflection point, classically seen as the beginning of overdistension, may also indicate the end of recruitment. The pressure/volume curve offers the unique opportunity of evaluating alveolar recruitment/derecruitment at the bedside that can be helpful for the identification of optimal ventilatory settings and makes the curve a valuable tool for the ventilatory management of acute lung injury.

Closed versus open suctioning techniques.

Airway suctioning is classically performed with the disconnection of the patient from the ventilator and the introduction of the suction catheter into the endotracheal tube. Alternatively, it can be accomplished with a closed suctioning system included in the ventilatory circuit, allowing to introduce the suction catheter into the airways without disconnecting the patient from the ventilator. The closed-suction system has some advantages compared to the conventional, open-suction technique. It can be helpful in limiting environmental, personnel and patient contamination and in preventing the loss of lung volume and the alveolar derecruitment associated with standard suctioning in the severely hypoxemic patients. However, the impact of the closed system on ventilator-associated pneumonia as well as its cost-effectiveness and the influence of such devices with ventilatory support remain to be assessed.

Alveolar derecruitment at decremental positive end-expiratory pressure levels in acute lung injury: comparison with the lower inflection point, oxygenation, and compliance.

We examined the hypothesis that recording multiple elastic pressure-volume (Pel/V) curves and calculating alveolar derecruitment (V(DER)) induced by decreasing positive end-expiratory pressure (PEEP) may allow determination of alveolar closing pressures, thus helping to select the optimal PEEP level. V(DER) measured in 16 patients with acute lung injury (ALI) was compared with the lower inflection point (LIP) and oxygenation changes. A modified automated method was used to record multiple Pel/V curves at low constant flow. PEEP was decreased in 5-cm H(2)O steps, from 20 or 15 cm H(2)O to 0 cm H(2)O (ZEEP). V(DER) was the volume loss between the curves recorded from PEEP and from ZEEP at the same Pel. Derecruitment occurred at each PEEP decrement, being spread almost uniformly over the 20/15 to 0 cm H(2)O range. V(DER) was not correlated with LIP. V(DER) changes correlated with Pa(O(2))/FI(O(2)) changes (rho = 0.6, p = 0.02). Linear compliance at ZEEP was correlated to V(DER) at PEEP 15 cm H(2)O (rho = 0.9, p = 0.001), suggesting that compliance above LIP may reflect the amount of recruitable lung. Thus, alveolar closure in ALI occurs over a wide range of pressures, and LIP is a poor predictor of alveolar closure.

Influence of tidal volume on alveolar recruitment. Respective role of PEEP and a recruitment maneuver.

Both reduction in tidal volume (VT) and alveolar recruitment may be important to limit ventilator-associated lung injury during mechanical ventilation of patients with the acute respiratory distress syndrome (ARDS). The aim of this study was to assess the risk of alveolar derecruitment associated with VT reduction from 10 to 6 ml/kg. Whether this VT-related derecruitment could be reversed, either by a recruitment maneuver or by an increase in positive end-expiratory pressure (PEEP) level, was also investigated. Fifteen patients with ARDS were successively ventilated using conventional VT (CVT = 10 +/- 1 ml/kg) and low VT (LVT = 6 +/- 1 ml/ kg); total PEEP (PEEPtot) was individually set at the lower inflection point (Plip) of the pressure-volume curve (PEEPtot = 11 +/- 4 cm H(2)O). Pressure-volume curves were recorded from zero PEEP (ZEEP) and from PEEP, and recruited volume (Vrec) was calculated as the volume difference between the two curves for a given pressure. Despite a similar PEEPtot, Vrec was significantly lower with LVT than with CVT, indicating low VT-induced alveolar derecruitment. Reduction in VT was associated with a reduced Sa(O(2)). In 10 patients, Vrec was also measured before and after a recruitment maneuver (two sustained inflations at 45 cm H(2)O), and after an increase in PEEP (by 4 cm H(2)O). Low VT-induced derecruitment was reversed by a recruitment maneuver and by increasing PEEP. We conclude that a reduction in VT could be responsible for alveolar derecruitment, which may be transiently reversed by a reexpansion maneuver or prevented by a PEEP increase above Plip.

Pressure-volume curve: methods and meaning.

The pressure-volume curve of the respiratory system is a physiological method used for diagnotic purposes to describe the static mechanical properties of the respiratory system. A renewal of interest in the pressure-volume curve has recently appeared because of experimental evidence regarding the information conveyed by the curve, a better understanding of the pathophysiologic factors influencing its interpretation and the beneficial results of clinical trials based on the use of the pressure-volume curve for ventilatory management of acute respiratory distress syndrome. Thus, adapting ventilatory settings to individual characteristics of the patients in terms of respiratory mechanics may be an extremely important aspect for a better management of the most difficult to ventilate patients with acute lung injury. There is considerable experimental evidence that both the opening-collapse phenomena and the excessive lung stretch may cause damage to the lungs. Therefore tools allowing an individual titration of ventilatory settings taking into account the constraints of the respiratory system seem highly desirable. The pressure-volume curve might be easily achievable at the bedside as a monitoring tool. The low-flow technique using ventilator technology has several potential advantages. It is hopeful to think that in the future the measurement of the P-V curve and the quantification of alveolar recruitment may be easily provided at the bedside and may help for the titration of the ventilatory settings in clinical practice. This review will focus briefly on the physiologic background, technique description, and recent advances concerning the interpretation of the P-V curve in the critically ill patients.

Continuous positive airway pressure during fiberoptic bronchoscopy in hypoxemic patients. A randomized double-blind study using a new device.

Fiberoptic bronchoscopy (FOB) may worsen oxygenation and clinical status in severely hypoxemic patients. We conducted a prospective, randomized double-blind trial to compare the delivery of continuous positive airway pressure (CPAP) as a tool for maintaining oxygenation during FOB, to the delivery of oxygen only. Thirty consecutive patients who needed FOB for diagnostic purposes were enrolled. Their arterial oxygen pressure (Pa(O(2))) to inspired oxygen fraction (FI(O(2))) ratio was below 300 mm Hg. CPAP was generated by a simple new device open to the atmosphere. During FOB and the 30 min thereafter, pulse oximetry values (Sp(O(2))) were significantly higher in the CPAP than the Oxygen group (95.7 +/- 1.9% versus 92.6 +/- 3.1, p = 0.02). The lowest Sp(O(2)) values were observed in the Oxygen group (93.5 +/- 2.4% versus 88.6 +/- 3.4, p = 0.002). Arterial blood gases 15 min after FOB showed that Pa(O(2)) had increased in the CPAP group and decreased in the Oxygen group (DeltaPa(O(2)) = +10.5% +/- 16.9 versus -15% +/- 16.6, p = 0.01). Five patients in the Oxygen group, but none in the CPAP group, developed respiratory failure in the 6 h after FOB and required ventilatory assistance (p = 0.03). We conclude that in hypoxemic patients, the use of a new CPAP device during FOB allowed minimal alterations in gas exchange and prevented subsequent respiratory failure.

[Surgery of loco-regional recurrences in colorectal cancer]. / Chirurgia delle recidive loco-regionali del cancro del colon e del retto.

By the term of local recurrence (LR), after apparently curative resection of a colorectal cancer, we mean the recurrence of the disease at the site of the original tumor, in correspondence to the regional lymph nodes or to intestinal anastomosis. The frequency of LR, which differs widely from one case to another because of the unhomogenity of the samples under examination, is on average around 16%, although this figure is to be considered an underestimation since it is not supported by routine autopsies. The authors analyse, together with the data in the literature, the results of their personal experience relating to 1164 patients undergoing surgery for colorectal cancer in the space of 18 years, in order to evaluate the true effectiveness of surgery on patients affected by LR. Surgery on the original tumor had a curative aim in 791 (68%) of these cases, 33 patients died during the postoperative period and 37 were lost to follow-up. Among the remaining 721 patients, recurrence was observed in 218 cases (30.2%): in 81 of these was confirmed a LR, with simultaneous distant metastasis in 45. During the same time span, 15 patients were admitted who were affected by LR from colorectal cancers treated surgically in other hospitals. Of these, only 2 had concomitant distant metastasis. 58 of these 96 patients (60.4%) underwent surgery, which had a curative aim in 22 cases (37.9%)/ Up to present, 12 patients undergoing curative surgery are still alive, 4 (33.3%) being affected by further relapse. The data reported demonstrate that in patients with proven LR surgical intervention is widely indicated, being the only therapeutic approach able to provide tangible results. However, the choice of exeresis must be carefully weighed: surgery of LR can be said to be truly curative in few cases, and thus the operative risks may not be acceptable in situations where limited results, in terms of duration and quality, are foreseen.

[The prognostic evaluation of acute pancreatitis]. / Valutazione prognostica della pancreatite acuta.

Early identification of severity is one of the most important problems in acute pancreatitis, both for decision-making and classification. Predictive criteria show a wide range of accuracy: clinical examination (on admission: 76-85%); single laboratory data (PCR: 68-98%, C3-C4: 63-72%); multifactorial scoring systems (Ranson: 65-82%, Imrie: 78-95%); diagnostic peritoneal lavage (72-90%); CT features (52-81%). In 1982 we started a prospective evaluation of the prognostic performances of a bayesian statistical model for the prediction of severe vs mild pancreatis and death vs survival, which uses the outcome-related patterns of several variables, assuming their independence, analysed on a data of 44 patients. The performances have been calculated prospectively by comparing the expected vs actual results on 88 further patients (accuracy, sensitivity and specificity, respectively, in the prediction of severe pancreatitis: 92%, 92%, 93%; in the prediction of death: 95%, 97%, 87%). Moreover, the model can represent classes of risk by combining prediction of death + severe pancreatitis (DSP), survival + severe pancreatitis (SSP) and survival + mild pancreatitis (SMP) (accuracy, sensitivity and specificity, respectively, in the prediction of DSP: 97%, 83%, 100%; in the prediction of SSP: 95%, 87%, 97%; in the prediction of SMP: 95%, 97%, 90%). Our model enables clinicians dealing with other population to re-determine different variables or integrate them with new information, whenever available. It seems to be transferable and adaptable, even with a probable further increase of the performances, without compromising the objectivity of the predictive judgement and the homogeneity of the classes of risk.