Ventilación protectora en anestesia general. ¿Algo nuevo? / Protective Ventilation in general anesthesia. Anything new?

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A randomised controlled trial comparing two popliteal nerve catheter tip positions for postoperative analgesia after day-case hallux valgus repair.

We compared the effect of two different positions of a sciatic nerve catheter within the popliteal fossa on local anaesthetic consumption and postoperative analgesia in patients undergoing day-case hallux valgus repair. Eighty-four patients were randomly allocated to receive a sciatic nerve catheter either between the tibial and peroneal components (sciatic group) or medial to the tibial nerve (tibial group). The primary endpoint was postoperative local anaesthetic consumption, while secondary endpoints were pain scores, number of occasions where sleep was disturbed by pain and incidence of insensate limb and foot drop at 24 h and 48 h postoperatively. Postoperative median (IQR [range]) local anaesthetic consumption was 126 (106-146 [98-180]) ml in the sciatic group versus 125 (114-158 [98-200]) ml in the tibial group (p = 0.103). Insensate limb occurred in 14 patients in the sciatic group versus one patient in the tibial group (p < 0.001), while foot drop was reported by six patients in the sciatic group and none in the tibial group (p = 0.012). Sciatic nerve catheter placement medial to the tibial nerve may be a superior analgesic technique for day-case foot surgery.

A randomised controlled trial of intrathecal blockade versus peripheral nerve blockade for day-case knee arthroscopy.

We allocated 100 patients scheduled for day-case knee arthroscopy to unilateral spinal anaesthesia with 40 mg intrathecal hyperbaric prilocaine or to ultrasound-guided femoral-sciatic nerve blockade with 25 ml mepivacaine 2%, 50 participants each. The median (IQR [range]) time to walk was 285 (240-330 [160-515]) min after intrathecal anaesthesia vs 328 (280-362 [150-435]) min after peripheral nerve blockade, p = 0.007. The median (IQR [range]) time to home discharge was 310 (260-350 [160-520]) min after intrathecal anaesthesia vs 335 (290-395 [190-440]) min after peripheral nerve blockade, p = 0.016. There was no difference in time from anaesthetic preparation to readiness for surgery.

Update on percutaneous mitral valve therapy: clinical results and real life experience.

Mitral regurgitation (MR) is a common valvulopathy worldwide increasing in prevalence. Cardiac surgical intervention, preferable repair, is the standard of care, but a relevant number of patients with severe MR do not undergo surgery because of high peri-operative risk. Percutaneous mitral valve repair with the MitraClip System has evolved as a new tool for the treatment of severe MR. The procedure simulates the surgical edge-to-edge technique, developed by Alfieri in 1991, creating a double orifice valve by a permanent approximation of the two mitral valve leaflets. Several preclinical studies, registries and Food and Drug Administration approved clinical trials (EVEREST, ACCESS-EU) are currently available. The percutaneous approach has been recently studied in a randomized controlled trial, concluding that the device is less effective at reducing MR, when compared with surgery, by associated with a lower adverse event rate. The patients enrolled in this trial had a normal surgical risk and mainly degenerative MR with preserved left ventricular function. On the other hand, results derived from the clinical "real life" experience, show that patients actually treated in Europe present a higher surgical risk profile, more complex mitral valve anatomy and functional MR in the most of cases. Thus these data suggest that MitraClip procedure is feasible and safe in this subgroup of patients that should be excluded from the EVEREST trial due to rigid exclusion criteria. Despite the promising results clinical experience is still small, and no data related the durability are currently available. Therefore, MitraClip device should be reserved now to high risk or inoperable patients.

Pulmonary and extrapulmonary acute respiratory distress syndrome are different.

Acute respiratory distress syndrome (ARDS) can be derived from two pathogenetic pathways: a direct insult on lung cells (pulmonary ARDS (ARDSp)) or indirectly (extrapulmonary ARDS (ARDSexp)). This review reports and discusses differences in biochemical activation, histology, morphological aspects, respiratory mechanics and response to different ventilatory strategies between ARDSp and ARDSexp. In ARDSp the direct insult primarily affects the alveolar epithelium with a local alveolar inflammatory response while in ARDSexp the indirect insult affects the vascular endothelium by inflammatory mediators through the bloodstream. Radiological pattern in ARDSp is characterised by a prevalent alveolar consolidation while the ARDSexp by a prevalent ground-glass opacification. In ARDSp the lung elastance, while in ARDSexp the chest wall and intra-abdominal chest elastance are increased. The effects of positive end-expiratory pressure, recruitment manoeuvres and prone position are clearly greater in ARDSexp. Although these two types of acute respiratory distress syndrome have different pathogenic pathways, morphological aspects, respiratory mechanics, and different response to ventilatory strategies, at the present, is still not clear, if this distinction can really ameliorate the outcome.

[A rationale basis for airways conditioning: too wet or not too wet? ]. / Una base razionale per il condizionamento delle vie aeree: umidificare troppo o non troppo?

Medical gases conditioning during mechanical invasive ventilation is nowadays a problem. In fact, in spite of conditioning guidelines, absolute humidity (AH) into 25-35 mg/l, clinical evaluation of the optimal level of airway humidification has not yet been established with certainty. Physiologically, during spontaneous respiration the airway hydric balance, inspiratory AH expiratory AH, is negative of 27 mg/l about. Usually the patients on mechanical ventilation have an expiratory AH of 32-33 mg/l. An overhumidification of inspired gases, positive airway hydric balance, gives anatomic-physiological alterations of airways and lung parenchyma. During invasive mechanical ventilation, the practice of active hot humidifiers has a positive or level airway hydric balance. We think that inspired AH must be equal to expired AH to maintain an airway hydric balance at least level. At last, the temperature of inspired gases, with active hot humidifiers, shouldn't exceed 32-34 degrees C.

The abdominal compartment syndrome. Clinical relevance.

Increased intra-abdominal pressure (IAP) may occur in a number of different situations encountered by intensivists, such as tense ascites, abdominal hemorrhage, use of military antishock trousers, abdominal obstruction, during laparoscopy, large abdominal tumors and peritoneal dialysis.1-3 Both clinical and experimental evidence indicate that increased IAP may adversely affect cardiac, renal, respiratory and metabolic functions.1-5 Despite this, increased IAP is rarely recognized and treated in Intensive Care Unit (ICU) settings. There appears to be two reasons for this: the physiologic consequences of increased IAP are not well know, to most physicians and, more importantly, the capability of easily measuring IAP has not been well documented. In this chapter, we will discuss: 1) the different methods proposed to evaluate IAP in ICU; 2) the physiopathological consequences of increased IAP; 3) the existing clinical data about IAP in critically ill patients. Considering overall our data, we can conclude that: 1) different techniques are available at the bedside to estimate the IAP; 2) the IAP ranges between 10 and 20 cmH2O, substantially increased compared to normal subjects. Most of the patients have IAH, while few of them (<5%) present clinical characteristics of ACS; 3) the IAP is different among different categories of patients and its increase is not limited to surgical patients only; 4) the increase in IAP appears to influence respiratory function, homodynamic, kidney, gut and brain physiology; 5) the IAP seems to be correlated with severity scores but its relation to mortality is controversial; 6) the routine measurements of IAP by means of bladder pressure are not associated with an increased rate of urinary tract infections.

Respiratory mechanics in brain injured patients.

BACKGROUND: Brain injured patients have an increased risk of extracerebral organ failure, mainly pulmonary dysfunction. The prevalent cause of pulmonary failure is ventilator associated pneumonia (VAP) which increases morbidity and mortality. The respiratory dysfunction is mainly characterized by the presence of alveolar consolidation of the dependent lobes. METHODS: We investigated the mechanical changes of the respiratory system and the effects of positive end-expiratory pressure (PEEP) in 10 normal subjects, in 10 brain injured patients without respiratory failure and in 10 brain injured patients with respiratory failure (PaO2/FiO2 lower than 200 mmHg) due to VAP. RESULTS: We found that: 1) Intra-Abdominal Pressure (IAP) was increased in brain injured patients with or without respiratory failure compared to normal subjects; 2) the Elastance of respiratory system (Est,rs), the Elastance of the chest wall (Est,cw) and Resistance max of the Lung (Rmax,L) increased in brain injured patients independently from the presence of respiratory failure; 3) in brain injured patients with respiratory failure application of 15 cmH2O of PEEP increased the Elastance of the Lung (Est,L), Est,rs and Rmax,L, while did not result in significant alveolar recruitment and oxygenation improvement. CONCLUSIONS: In conclusion, in brain injured patients 1) the respiratory mechanics is altered; 2) PEEP is uneffective to improve respiratory function in respiratory failure due to ventilator associated pneumonia. Further studies are warranted to better elucidate the pathophysiology and clinical management of respiratory dysfunction in brain injured patients.

[Observing an SSU Em 118 dispatch center for continuous quality improvement. The case of SSUEm 118 Varese]. / Una centrale operativa SSU Em 118 a giudizio per verifica e revisione di qualità. Il caso SSU Em 118 Varese.

The present paper highlights quality aspects of the management of an Emergency Health Service Center (SSUEm 118, Varese) in order to identify the corrective measures required in a service that is increasingly close to the citizens real needs and expectations. Data were collected retrospectively on a total 54,301 calls for assistance in the period October 1997-March 1999 from an area covering some 1,300 sq.km with a population of 1,150,000 residents. That resident population was dramatically increased on a daily basis by heavy vehicle traffic particularly on the motorways to the area's many factories and to the Intercontinental Airport Malpensa 2000. The survey employed 7 anaesthetists and resuscitation staff, 14 nurses and 8 Italian Red Cross works from the Emergency Center. The researchers analysed the following phases: call reception and telephone conversation: ambulance dispatch, patient transportation and the alerting of the hospital of destination. The ServFMEA method was used for Quality Control with appropriate dispatch and the conduct and timing of the ambulance service in the Varese SSUEm 118 area. The data collected allowed for a detailed analysis of the accuracy of the information provided over the telephone (over-triage 58%, undertriage 2%), the usefulness of the telephone filter, the colour coding (correct in 40% of cases), pick-up times (5'40" on average) which were related to problems inherent in the ambulance call-out and the way ambulances reached the emergency (BLS 99%, ALS 1%, Air rescue < 1%). It was concluded that Varese SSUEm 118 was effectively and efficiently run in its first 18 months and results were improved as far as they could be given the inadequate funding of the Italian Heatlh Service.

Postoperative bleeding after coronary revascularization. Comparison between tranexamic acid and epsilon-aminocaproic acid.

BACKGROUND: Microvascular bleeding after Cardiopulmonary bypass (CPB) is mainly due to consumption of clotting factors, platelets damage, and hyperfibrinolysis. Aprotinin, the only antifibrinolytic drug effective in preserving platelets, is no longer available; an alternative regimen based on pure antifibrinolytic drugs has been proposed, since hyperfibrinolysis is known to contribute both to clot lysis and platelet dysfunction. In this study the efficacy of two antifibrinolytic drugs, Tranexamic acid (TA) and epsilon-aminocaproic acid (EACA), was tested in patients undergoing cardiopulmonary bypass (CPB), for primary myocardial revascularization. METHODS: Forty-eight consecutive patients were randomized to receive prophylactically equipotent doses of EACA (group A) or TA (Group B). Platelet count, prothrombin time, fibrin digestion products, blood loss and transfusion requirements recorded after 6 and 24 hours from the end of surgery were compared. RESULTS: The two groups were comparable for length of CPB and numbers of grafts; no significant difference was observed in the coagulation parameters considered. Blood losses were less in group B (TA) than in group A (EACA), both at 6 and 24 hours after surgery; homologous blood transfused was also less in group B, but no difference was statistically significant. No adverse effect was observed. CONCLUSIONS: In coronary patients, TA and EACA exhibit the same effects on blood loss and requirements after CPB; either drug can be safely used in cardiac surgery.

[Systemic and pulmonary vascular resistance in brain death]. / Resistenze vascolari sistemiche e polmonari nella morte cerebrale.

BACKGROUND: Hemodynamic instability is known to affect brain dead subjects and it can be dangerous for the viability of transplantable organs. Aim of the present study was to assess the hemodynamic performance in brain dead subjects, the changes during the legal observation period and the results of therapeutic management. METHODS: The authors evaluated 28 consecutive adult brain dead subjects, all in intensive treatment, controlled ventilation, infusion therapy and/or dopamine administration and continuous direct monitoring of arterial pressure. Ten hemodynamic parameters have been registered by the thermodilution method and the Swann-Ganz catheter. The Legal Committee performed measurements at the beginning (T0) and the end (T6) of the observation period, which lasts 6 hours according to the current law on death certification (Law N. 578/93). RESULTS: Low systemic and pulmonary vascular resistances have been documented in the majority of subjects (75%), both treated only with fluids and with the additional dopamine administration (dosage lower than 10 ug/Kg/min). The above-mentioned reduction was similar at the two different monitored times (T0 and T6). CONCLUSIONS: This situation can be ascribed to the destruction of the cerebral vasoactive centers and the consequent hypotension is due to autonomic nervous system dysfunction. Hemodynamic instability must be treated by fluids and inotropic drugs, but they may cause cardiac and respiratory problems, thus it is suggested to use also low doses of vasoconstrictive drugs, provided that cardiac condition allows this therapeutic strategy.

[Comparison of SAPS II, MPM II24 and SAPS in intensive care]. / Confronto fra SAPS II, MPM II24 e SAPS in terapia intensiva.

OBJECTIVE: To compare the performance of the new SAPS II, new MPM2 and SAPS in a cohort of patients admitted to our polyvalent ICU. DESIGN: the ability of the SAPS II scoring system to predict the probability of hospital mortality was assessing calibration and discrimination (ROC curve) measures obtained using published coefficients and within relevant subgroups using formal statistic assessment (goodness of fit). PATIENTS: from May 1997 to May 1998, 420 consecutive patients over 18 years old. RESULTS: When the parameters based on the standard model were applied, the SAPS II discrimination (area under ROC curve) was = 0.889 and calibration (chi square test) of SAPS II was = 4.448 with p = 0.879; MPM2 chi 2 = 0.9385, p = 0.402 and SAPS chi 2 = 27.089, p = 0.0001. The performance of SAPS II model was very good. Worst predictive accuracy was achieved in trauma and elective surgery patients. CONCLUSIONS: SAPS II model gave good results in terms of calibration and discrimination. SAPS II has better accuracy then SAPS and MPM2. Concerning the performance of models, large differences were apparent in relevant subgroups: trauma and sepsis patients. Moreover the choice of adequate statistic method to compare intensive care populations appeared to need more research.

[Hormone evaluation in brain death]. / Alcune valutazioni ormonali nella morte cerebrale.

BACKGROUND: In this study, the level and the variation of a number of hormone and metabolic parameters during brain death treatment in potential organ donors have been monitored. METHODS: Thirty-nine consecutive brain-dead patients were enrolled in 3 Intensive Care Units of Regional Hospitals of the North of Italy. All patients were potential organ donors and free from diseases before the accident leading to death. The levels of ADH, ACTH, TSH, prolactin, cortisol, aldosterone, FT3, FT4, renin, serum lactate and plasma osmolality were measured immediately after the diagnosis of brain death (T0), certified following the Italian law of December 29, 1993, n. 578, and after 6 hours (T6). RESULTS: Hormone levels were normal in the majority of subjects, and there was no significant variation during the 6 hours of the observation period. No correlation was found between the hormone levels considered and the metabolic parameters; ADH levels were not correlated with plasma osmolality. FT3 levels were below the normal range in the majority of subjects, but were not associated with a higher lactate level, which is used as a marker of a shift toward tissue anaerobic metabolism. CONCLUSIONS: In conclusion, triiodothyronine administration to improve metabolic order and thus the function of organs for transplantation is not justified in brain-dead patients.

[Septic pancreatic necrosis in intensive care]. / La necrosi pancreatica infetta in terapia intensiva.

BACKGROUND: Infected necrotizing pancreatitis is the most fulminant variety of this disease. The reported mortality is up to 50%. The haemodynamic features of cardiovascular instability has many similarities to sepsis syndrome, septic shock and multiple organ dysfunction syndrome (MODS). The purpose of this study is to review personal experience in the ICU (hospital of Varese) to determine etiology, treatment and complications. METHODS: Twenty patients treated since 1988 with infected necrotizing pancreatitis required surgical treatment and mechanical ventilation. RESULTS: The mortality rate was 60% and ICU-stay was 26.5 +/- 12.3 days, the median age was 54 +/- 13. Ranson's criteria at admission to the ICU was 6.6 +/- 1.2, Glasgow point was 4.6 +/- 1.2 (5.5 +/- 0.87 died, 3.2 +/- 0.8 survived p < 0.01), Baltazar score 6.2 +/- 2.1 (7.4 +/- 2.1 died, 5.5 +/- 0.9 survived p < 0.05) and SAPS II score 43.4 +/- 12.1 (50.1 +/- 7.8 died, 34 +/- 5.5 survived p < 0.01). The etiology was: gallstones (45%), alcoholism (15%), ERCP (15%) and idiopathic in 25%. Serum pancreatic amylase was 342 +/- 113.9 U/l (550 +/- 100 died, 155 +/- 60 survived p < 0.01), lipase was 334 +/- 176 U/l and transaminases GOT was 123 +/- 46 u/l (156 +/- 90 died, 29 +/- 7 survived p < 0.05). High initial amylase and GOT levels were frequently found in non survived patients. MODS occurred in 17 cases (85%), ARDS in 2 patients (10%), abdominal bleeding in 6 (30%) and septic syndrome in 8 (40%). CONCLUSIONS: It is thus possible that a target-oriented approach including fluid replacement, rapid correction of intestinal underperfusion, inotropic and antibiotic therapy, supply of specific nutrients and other therapeutic strategies as open laparostomy must be employed to prevent MODS or septic syndrome in pancreatic infection after acute necrotizing pancreatitis.

The clinical use of 99m-Tc-labeled WBC scintigraphy in critically ill surgical and trauma patients with occult sepsis.

OBJECTIVE: To evaluate the clinical use of radionuclide-labeled white blood cell scintigraphy in the detection of focal sepsis. DESIGN: Prospective clinical study. SETTING: A medical/surgical 12-bed intensive care unit (ICU) in a university hospital. PATIENTS: 26 trauma and surgical patients affected by sepsis of unknown origin were studied. MEASUREMENTS AND RESULTS: After the usual diagnostic approach, patients were submitted to a total body scan by using the patient's leukocytes labeled with technetium-99m (99m-Tc) HMPAO; three scintigraphy were performed within 20 h of tracer injection; the result of scan was completed with all clinical and instrumental data, including ultrasound (US) arnd computed tomography (CT), and the diagnostic efficacy was demonstrated for each patient on discharge from the ICU. The scan was able to detect 20 sites of infection; it was possible to rule out 11 suspected sites; only in two cases was the result considered to be false positive or false negative; in two cases the result was considered to be uncertain. These results show the high sensitivity (95%), specificity (91%) and accuracy (94%) of the method. CONCLUSIONS: In ICU patients with sepsis, nuclear medicine can provide additional data, as the injection of radionuclide-labeled white blood cells (WBCs) allows the imaging of sites of infection. Analysis of our results suggests that scintigraphy with 99m-Tc-labeled WBCs can be considered a useful tool in the detection of the source of infection.

Effect of recombinant IL-1 beta and recombinant gamma interferon on septic acute lung injury in mice.

The effect of recombinant human interleukin 1B (IL-1B) and recombinant human gamma interferon (IFN-g), when given prophylactically, in a mouse model of septic acute lung injury was studied. Mice were treated with various doses of IL-1B and IFN-g for 3 consecutive days prior to administration of lipopolysaccharide of Escherichia coli (1 mg/kg given intraperitoneally). To determine the histologic changes occurring after prophylactic administration of such cytokines, a scoring system was assessed. A significant reduction of edema and neutrophil accumulation into the lungs of mice was observed, especially at doses of 100 U per mouse and 10,000 U per mouse of IL-1B and IFN-g, respectively. Prophylactic administration of IL-1B or IFN-g caused histologic changes, including marked reduction of edema and neutrophil accumulation in the interstitial and alveolar spaces. Combined prophylactic administration of IL-1B and IFN-g provoked a marked decrease of neutrophil accumulation into the lungs, but was not accompanied by significant reduction of edema or hemorrhage. These results provide evidence for the beneficial role of IL-1B and IFN-g in the abnormality of septic acute lung injury by reducing inflammatory lesions.

Use of heat and moisture exchanging (HME) filters in mechanically ventilated ICU patients: influence on airway flow-resistance.

OBJECTIVE: To investigate the flow-resistance of a new generation of Heat Moisture Exchanging Filters (HME filters) during 24 h of clinical use. DESIGN: Before-after trial. SETTING: A general Intensive Care Unit of a university hospital. PATIENTS: A consecutive series of 96 patients undergoing mechanical ventilation for respiratory insufficiency of various etiology and severity. METHODS: The characteristics of the secretions collected by tracheal suctioning and the pressure/flow relationship of the HMEs before and after 24 h of clinical use were analyzed. RESULTS: The resistance of the HMEs when dry was 2 hPa/l.s, and it increased to a maximum of 1 hPa/l.s in 83% of the patients after 24 hours; in four patients with particularly heavy secretions HME resistance was 4-5 hPa/l.s. There were no significant modifications of the secretions within the investigation period, excluding, in particular, an increase in density with consequent tracheal tube obstruction. CONCLUSION: The gas conditioning efficiency and design performance of the tested HMEs did not create a significant obstacle to airflow medium term mechanical ventilation; however, these devices should be cautiously used in patients with heavy bronchial secretions.