Carlo Alberto Volta

Emotional and interpersonal factors are most important for patient satisfaction with anaesthesia

Background:  Questionnaires to evaluate patient satisfaction with anaesthesia mainly consider physiological aspects. This study was performed to identify the items of value for patients having anaesthesia (pilot phase) and to validate the questionnaire built on these findings in a new group of inpatients.

Physiologic Effects of High-flow Nasal Cannula in Acute Hypoxemic Respiratory Failure.

Rationale: High‐flow nasal cannula (HFNC) improves the clinical outcomes of nonintubated patients with acute hypoxemic respiratory failure (AHRF). Objectives: To assess the effects of HFNC on gas exchange, inspiratory effort, minute ventilation, end‐expiratory lung volume, dynamic compliance, and ventilation homogeneity in patients with AHRF. Methods: This was a prospective randomized crossover study in nonintubated patients with AHRF with PaO2/setFiO2 less than or equal to 300 mm Hg admitted to the intensive care unit. We randomly applied HFNC set at 40 L/min compared with a standard nonocclusive facial mask at the same clinically set FiO2 (20 min/step). Measurements and Main Results: Toward the end of each phase, we measured arterial blood gases, inspiratory effort, and work of breathing by esophageal pressure swings (&Dgr;Pes) and pressure time product, and we estimated changes in lung volumes and ventilation homogeneity by electrical impedance tomography. We enrolled 15 patients aged 60 ± 14 years old with PaO2/setFiO2 130 ± 35 mm Hg. Seven (47%) had bilateral lung infiltrates. Compared with the facial mask, HFNC significantly improved oxygenation (P < 0.001) and lowered respiratory rate (P < 0.01), &Dgr;Pes (P < 0.01), and pressure time product (P < 0.001). During HFNC, minute ventilation was reduced (P < 0.001) at constant arterial CO2 tension and pH (P = 0.27 and P = 0.23, respectively); end‐expiratory lung volume increased (P < 0.001), and tidal volume did not change (P = 0.44); the ratio of tidal volume to &Dgr;Pes (an estimate of dynamic lung compliance) increased (P < 0.05); finally, ventilation distribution was more homogeneous (P < 0.01). Conclusions: In patients with AHRF, HFNC exerts multiple physiologic effects including less inspiratory effort and improved lung volume and compliance. These benefits might underlie the clinical efficacy of HFNC.

The effect of volatile anesthetics on respiratory system resistance in patients with chronic obstructive pulmonary disease.

We examined the effect of isoflurane and sevoflurane on respiratory system resistance (Rmin,rs) in patients with chronic obstructive pulmonary disease (COPD). The diagnosis of COPD rests on the presence of airway obstruction, which is only partially reversible after bronchodilator treatment. Ninety-six consecutive patients undergoing thoracic surgery for peripheral lung cancer were enrolled. They were divided into two groups: preoperative forced expiratory volume in 1 s/forced vital capacity ratio <70% or >70%. Rmin,rs was measured after 5 and 10 min of maintenance anesthesia by using the constant flow/rapid occlusion method. Maintenance of anesthesia was randomized to thiopental 0.30 mg · kg−1 · min−1 or 1.1 minimum alveolar anesthetic concentration end-tidal isoflurane or sevoflurane. Eleven patients were excluded: two because anesthesia was erroneously induced with propofol and nine because of an incorrect tube position. Maintenance with thiopental failed to decrease Rmin,rs, whereas both volatile anesthetics were able to decrease Rmin,rs in patients with COPD. The percentage of patients who did not respond to volatile anesthetics was larger in those with COPD as well. In conclusion, we have demonstrated that isoflurane and sevoflurane produce bronchodilation in patients with COPD.

Hospital mortality of adults admitted to Intensive Care Units in hospitals with and without Intermediate Care Units: a multicentre European cohort study

IntroductionThe aim of the study was to assess whether adults admitted to hospitals with both Intensive Care Units (ICU) and Intermediate Care Units (IMCU) have lower in-hospital mortality than those admitted to ICUs without an IMCU.MethodsAn observational multinational cohort study performed on patients admitted to participating ICUs during a four-week period. IMCU was defined as any physically and administratively independent unit open 24 hours a day, seven days a week providing a level of care lower than an ICU but higher than a ward. Characteristics of hospitals, ICUs and patients admitted to study ICUs were recorded. The main outcome was all-cause in-hospital mortality until hospital discharge (censored at 90 days).ResultsOne hundred and sixty-seven ICUs from 17 European countries enrolled 5,834 patients. Overall, 1,113 (19.1%) patients died in the ICU and 1,397 died in hospital, with a total of 1,397 (23.9%) deaths. The illness severity was higher for patients in ICUs with an IMCU (median Simplified Acute Physiology Score (SAPS) II: 37) than for patients in ICUs without an IMCU (median SAPS II: 29, P <0.001). After adjustment for patient characteristics at admission such as illness severity, and ICU and hospital characteristics, the odds ratio of mortality was 0.63 (95% CI 0.45 to 0.88, P = 0.007) in favour of the presence of IMCU. The protective effect of the IMCU was absent in patients who were admitted for basic observation, for example, after surgery (odds ratio 1.15, 95% CI 0.65 to 2.03, P = 0.630) but was strong in patients admitted to an ICU for other reasons (odds ratio 0.54, 95% CI 0.37 to 0.80, P = 0.002).ConclusionsThe presence of an IMCU in the hospital is associated with significantly reduced adjusted hospital mortality for adults admitted to the ICU. This effect is relevant for the patients requiring full intensive treatment.Trial registrationClinicaltrials.gov NCT01422070. Registered 19 August 2011.

Influence of Different Strategies of Volume Replacement on the Activity of Matrix Metalloproteinases: An in Vitro and in Vivo Study

Background:Excessive production of matrix metalloproteinase 9 (MMP-9) is linked to tissue damage and anastomotic leakage after large bowel surgery. Hence, the aim of this study was to verify whether different strategies of fluids administration can reduce MMP-9 expression. Methods:In the in vitro experiment, the authors tested the hypothesis of a direct inhibition of MMP-9 by the fluids used perioperatively, i.e., lactated Ringers solution, 3.4% poligeline, and hydroxyethyl starch 130/0.4. In the in vivo experiment, 36 patients undergoing surgery for colon cancer were randomly assigned to three groups to receive lactated Ringers solution, poligeline, or hydroxyethyl starch. MMP-9 and tissue inhibitor of metalloproteinases were measured from venous blood samples; the MMP-9/tissue inhibitor of metalloproteinases ratio was calculated as an index of equilibrium between the action of MMP-9 and its inhibition. Results:In the in vitro experiment, the presence of hydroxyethyl starch 130/0.4 in the MMP-9 assay system showed a strong inhibition of the enzymatic activity compared with lactated Ringers solution. In the in vivo experiment, MMP-9 and tissue inhibitor of metalloproteinases plasma levels did not differ among the three groups at baseline, whereas those levels increased significantly at the end of surgery. At that time, the MMP-9 plasma levels and the MMP-9/tissue inhibitor of metalloproteinases ratio were significantly higher in the lactated Ringers solution and poligeline groups than in the hydroxyethyl starch group. These results were confirmed 72 h after surgery. Conclusions:This study demonstrates that hydroxyethyl starch 130/04 decreases the circulating levels of MMP-9 in patients undergoing abdominal surgery.

LMA Supreme™ vs i-gel™– a comparison of insertion success in novices

Two new supraglottic airway devices, the LMA Supreme™ (LMA) and the i‐gel™, offer potential benefits when inserted by inexperienced operators. This study compared the insertion success rate and ventilation profile between the LMA Supreme and the i‐gel when inserted by operators without previous airway management expertise. Following a short lecture and manikin training, airway novices were randomly allocated to insert either the LMA Supreme or the i‐gel into 80 patients undergoing breast surgery. The primary outcome was first‐time success rate, and secondary outcomes were overall success rate, insertion time, airway leak pressure, tidal volume during pressure controlled ventilation at 17 cmH2O, and adverse events. First‐time insertion success rate was significantly higher for the LMA Supreme than the i‐gel (30/39 (77%) vs 22/41 (54%); p = 0.029). Significantly more placement failures occurred with the i‐gel (6 vs 0, p = 0.025). Mean (SD) leak pressure (29 (8) vs 23 (11) cmH2O, p = 0.007) and expired tidal volume (PCV 17 cmH2O) (785 (198) vs 654 (91), p = 0.001) were significantly greater with the LMA Supreme than with the i‐gel, respectively. More patients complained of pharyngolaryngeal pain with the LMA Supreme than with the i‐gel (17/39 (44%) vs 8/41 (20%); p = 0.053). We found better first time success rate, fewer failures, and a better seal with the LMA Supreme compared with the i‐gel, indicating that the LMA Supreme may be preferable for emergency airway use by novices.

Respiratory mechanics by least squares fitting in mechanically ventilated patients: application on flow-limited COPD patients

Abstract Objective: Although computerized methods of analyzing respiratory system mechanics such as the least squares fitting method have been used in various patient populations, no conclusive data are available in patients with chronic obstructive pulmonary disease (COPD), probably because they may develop expiratory flow limitation (EFL). This suggests that respiratory mechanics be determined only during inspiration. Setting: Eight-bed multidisciplinary ICU of a teaching hospital. Patients: Eight non-flow-limited postvascular surgery patients and eight flow-limited COPD patients. Intervention: Patients were sedated, paralyzed for diagnostic purposes, and ventilated in volume control ventilation with constant inspiratory flow rate. Measurements: Data on resistance, compliance, and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) obtained by applying the least squares fitting method during inspiration, expiration, and the overall breathing cycle were compared with those obtained by the traditional method (constant flow, end-inspiratory occlusion method). Results and conclusion: Our results indicate that (a) the presence of EFL markedly decreases the precision of resistance and compliance values measured by the LSF method, (b) the determination of respiratory variables during inspiration allows the calculation of respiratory mechanics in flow limited COPD patients, and (c) the LSF method is able to detect the presence of PEEPi,dyn if only inspiratory data are used.

In vivo calibration of esophageal pressure in the mechanically ventilated patient makes measurements reliable.

BackgroundEsophageal pressure (Pes) can provide information to guide mechanical ventilation in acute respiratory failure. However, both relative changes and absolute values of Pes can be affected by inappropriate filling of the esophageal balloon and by the elastance of the esophagus wall. We evaluated the feasibility and effectiveness of a calibration procedure consisting in optimization of balloon filling and subtraction of the pressure generated by the esophagus wall (Pew).MethodsAn esophageal balloon was progressively filled in 36 patients under controlled mechanical ventilation. VBEST was the filling volume associated with the largest tidal increase of Pes. Esophageal wall elastance was quantified and Pew was computed at each filling volume. Different filling strategies were compared by performing a validation occlusion test.ResultsFifty series of measurements were performed. VBEST was 3.5 ± 1.9 ml (range 0.5–6.0). Esophagus elastance was 1.1 ± 0.5 cmH2O/ml (0.3–3.1). Both Pew and the result of the occlusion test differed among filling strategies. At filling volumes of 0.5, VBEST and 4.0 ml respectively, Pew was 0.0 ± 0.1, 2.0 ± 1.9, and 3.0 ± 1.7 cmH2O (p < 0.0001), whereas the occlusion test was satisfactory in 22 %, 98 %, and 88 % of cases (p < 0.0001).ConclusionsUnder mechanical ventilation, an increase of balloon filling above the conventionally recommended low volumes warrants complete transmission of Pes swings, but is associated with significant elevation of baseline. A simple calibration procedure allows finding the filling volume associated with the best transmission of tidal Pes change and subtracting the associated baseline artifact, thus making measurement of absolute values of Pes reliable.

Matrix metalloproteinase-9 activity detected in body fluids is the result of two different enzyme forms.

In vitro activation of matrix metalloproteinase-9 (MMP-9) (Gelatinase B) with MMP-3 shows the presence of two different forms: an 82 kDa, N-terminal truncated form, and a 65 kDa, N- and C-terminal truncated form. So far the presence of the 65 kDa form has not been reported in vivo. Affinity chromatography was performed to separate MMP-9 from MMP-2 and immunoprecipitation to isolate ∼65 kDa MMP-9 from 82 kDa MMP-9 in sera of healthy donors. The presence of ∼65 kDa active MMP-9 was demonstrated both with gelatin zymography and western blot analysis. The ∼65 kDa MMP-9 lacks the haemopexin domain required for the high-affinity binding of the tissue inhibitor TIMP-1, and can be evaluated by activity assay in the presence of TIMP-1. This opens the possibility to investigate the role of this form of MMP-9 that escapes physiological regulation.

Pulmonary Function and Expiratory Flow Limitation in Acute Cervical Spinal Cord Injury

OBJECTIVE To identify the nature of the changes of respiratory mechanics in patients with middle cervical spinal cord injury (SCI) and their correlation with posture. DESIGN Clinical trial. SETTING Acute SCI unit. PARTICIPANTS Patients with SCI (N=34) at C4-5 level studied within 6 months of injury. INTERVENTIONS Patients were assessed by the negative expiratory pressure test, maximal static respiratory pressure test, and standard spirometry. MAIN OUTCOME MEASURES The following respiratory variables were recorded in both the semirecumbent and supine positions: (1) tidal expiratory flow limitation (TEFL); (2) airway resistances; (3) mouth occlusion pressure developed 0.1 seconds after occluded inspiration at functional residual capacity (P(0.1)); (4) maximal static inspiratory pressure (MIP) and maximal static expiratory pressure (MEP); and (5) spirometric data. RESULTS TEFL was detected in 32% of the patients in the supine position and in 9% in the semirecumbent position. Airway resistances and P(0.1) were much higher compared with normative values, while MIP and MEP were markedly reduced. The ratio of forced expiratory volume in 1 second to forced vital capacity was less than 70%, while the other spirometric data were reduced up to 30% of predicted values. CONCLUSIONS Patients with middle cervical SCI can develop TEFL. The presence of TEFL, associated with increased airway resistance, could increase the work of breathing in the presence of a reduced capacity of the respiratory muscles to respond to the increased load. The semirecumbent position and the use of continuous positive airway pressure can be helpful to (1) reduce the extent of TEFL and avoid the opening/closure of the small airways; (2) decrease airway resistance; and (3) maintain the expiratory flow as high as possible, which aids in the removal of secretions.