Isocapnic hyperventilation provides early extubation after head and neck surgery: A prospective randomized trial.

BACKGROUND: Isocapnic hyperventilation (IHV) shortens recovery time after inhalation anaesthesia by increasing ventilation while maintaining a normal airway carbon dioxide (CO2 )-level. One way of performing IHV is to infuse CO2 to the inspiratory limb of a breathing circuit during mechanical hyperventilation (HV). In a prospective randomized study, we compared this IHV technique to a standard emergence procedure (control). METHODS: Thirty-one adult ASA I-III patients undergoing long-duration (>3 hours) sevoflurane anaesthesia for major head and neck surgery were included and randomized to IHV-treatment (n = 16) or control (n = 15). IHV was performed at minute ventilation 13.6 ± 4.3 L/min and CO2 delivery, dosed according to a nomogram tested in a pilot study. Time to extubation and eye-opening was recorded. Inspired (FICO2 ) and expired (FETCO2 ) CO2 and arterial CO2 levels (PaCO2 ) were monitored. Cognition was tested preoperatively and at 20, 40 and 60 minutes after surgery. RESULTS: Time from turning off the vapourizer to extubation was 13.7 ± 2.5 minutes in the IHV group and 27.4 ± 6.5 minutes in controls (P < .001). Two minutes after extubation, PaCO2 was 6.2 ± 0.5 and 6.2 ± 0.6 kPa in the IHV and control group respectively. In 69% (IHV) vs 53% (controls), post-operative cognition returned to pre-operative values within 40 minutes after surgery (NS). Incidences of pain and nausea/vomiting did not differ between groups. CONCLUSIONS: In this randomized trial comparing an IHV method with a standard weaning procedure, time to extubation was reduced with 50% in the IHV group. The described IHV method can be used to decrease emergence time from inhalation anaesthesia.

Evaluation of a method for isocapnic hyperventilation: a clinical pilot trial.

BACKGROUND: Isocapnic hyperventilation (IHV) is a method that shortens time to extubation after inhalation anaesthesia using hyperventilation (HV) without lowering airway CO2 . In a clinical trial on patients undergoing long-duration sevoflurane anaesthesia for major ear-nose-throat (ENT) surgery, we evaluated the utility of a technique for CO2 delivery (DCO2 ) to the inspiratory limb of a closed breathing circuit, during HV, to achieve isocapnia. METHODS: Fifteen adult ASA 1-3 patients were included. After end of surgery, mechanical HV was started by doubling baseline minute ventilation. Simultaneously, CO2 was delivered and dosed using a nomogram developed in a previous experimental study. Time to extubation and eye opening was recorded. Inspired (FICO2 ) and expired (FETCO2 ) CO2 and arterial CO2 levels were monitored during IHV. Cognition was tested pre-operatively and at 20, 40 and 60 min after surgery. RESULTS: A DCO2 of 285 ± 45 ml/min provided stable isocapnia during HV (13.5 ± 4.1 l/min). The corresponding FICO2 level was 3.0 ± 0.3%. Time from turning off the vaporizer (1.3 ± 0.1 MACage) to extubation (0.2 ± 0.1 MACage) was 11.3 ± 1.8 min after 342 ± 131 min of anaesthesia. PaCO2 and FETCO2 remained at normal levels during and after IHV. In 85% of the patients, post-operative cognition returned to pre-operative values within 60 min. CONCLUSIONS: In this cohort of patients, a DCO2 nomogram for IHV was validated. The patients were safely extubated shortly after discontinuing long-term sevoflurane anaesthesia. Perioperatively, there were no adverse effects on arterial blood gases or post-operative cognition. This technique for IHV can potentially be used to decrease emergence time from inhalation anaesthesia.

Target temperature 34 vs. 36°C after out-of-hospital cardiac arrest - a retrospective observational study.

BACKGROUND: Intensive care for comatose survivors of cardiac arrest includes targeted temperature management (TTM) to attenuate cerebral reperfusion injury. A recent multi-center clinical trial did not show any difference in mortality or neurological outcome between TTM targeting 33°C or 36°C after out-of-hospital-cardiac-arrest (OHCA). In our institution, the TTM target was changed accordingly from 34 to 36°C. The aim of this retrospective study was to analyze if this change had affected patient outcome. METHODS: Intensive care registry and medical record data from 79 adult patients treated for OHCA with TTM during 2010 (n = 38; 34°C) and 2014 (n = 41; 36°C) were analyzed for mortality and neurological outcome were assessed as cerebral performance category. Student's t-test was used for continuous data and Fischer's exact test for categorical data, and multivariable logistic regression was applied to detect influence from patient factors differing between the groups. RESULTS: Witnessed arrest was more common in 2010 (95%) vs. 2014 (76%) (P = 0.03) and coronary angiography was more common in 2014 (95%) vs. 2010 (76%) (P = 0.02). The number of patients awakening later than 72 h after the arrest did not differ. After adjusting for gender, hypertension, and witnessed arrest, neither 1-year mortality (P = 0.77), nor 1-year good neurological outcome (P = 0.85) differed between the groups. CONCLUSION: Our results, showing no difference between TTM at 34°C and TTM at 36°C as to mortality or neurological outcome after OHCA, are in line with the previous TTM-trial results, supporting the use of either target temperature in our institution.

Effect of a chlorhexidine-containing brush-on gel on peri-implant mucositis.

OBJECTIVE: The aim was to evaluate the effect of a chlorhexidine-containing brush-on gel when used as supplement to oral hygiene instructions and mechanical debridement, on peri-implant mucositis in adults. MATERIALS AND METHODS: The study group consisted of 38 adults (48-87 years.) with peri-implant mucositis that were consecutively enrolled in three private clinics after informed consent. The study employed a double-blind controlled design with two parallel arms. After baseline registrations, oral hygiene reinforcement and mechanical debridement, the patients were randomly allocated to either a test group with once daily tooth brushing with an oral care brush-on gel containing 0.2% chlorhexidine digluconate (Cervitec Gel) or a control gel group. The duration of the intervention was 12 weeks. The primary outcome was bleeding on probing (BOP) and secondary endpoints were local plaque score (LPS) and pocket probing depth (PPD). RESULTS: The groups were balanced at baseline. The daily use of the chlorhexidine-containing gel resulted in reduced BOP after 4 and 12 weeks compared with the control group (P < 0.05). The PPD was significantly reduced (P < 0.05) after 12 weeks compared to baseline in the test group, but not in the control group. No side effects or adverse events were reported. CONCLUSION: The present findings indicated moderate but significant improvements of clinical parameters when mechanical debridement was combined with a self-applied oral care brush-on gel for the management of peri-implant mucositis.

Isocapnic hyperventilation shortens washout time for sevoflurane - an experimental in vivo study.

BACKGROUND: Isocapnic hyperventilation (IHV) is a method that fastens weaning from inhalation anaesthesia by increasing airway concentration of carbon dioxide (CO2 ) during hyperventilation (HV). In an animal model, we evaluated a technique of adding CO2 directly to the breathing circuit of a standard anaesthesia apparatus. METHODS: Eight anaesthetised pigs weighing 28 ± 2 kg were intubated and mechanically ventilated. From a baseline ventilation of 5 l/min, HV was achieved by doubling minute volume and fresh gas flow. Respiratory rate was increased from 15 to 22/min. The CO2 absorber was disconnected and CO2 was delivered (DCO2 ) to the inspiratory limb of a standard breathing circuit via a mixing box. Time required to decrease end-tidal sevoflurane concentration from 2.7% to 0.2% was defined as washout time. Respiration and haemodynamics were monitored by blood gas analysis, spirometry, electric impedance tomography and pulse contour analysis. RESULTS: A DCO2 of 261 ± 19 ml/min was necessary to achieve isocapnia during HV. The corresponding FICO2 -level remained stable at 3.1 ± 0.3%. During IHV, washout of sevoflurane was three times faster, 433 ± 135 s vs. 1387 ± 204 s (P < 0.001). Arterial CO2 tension and end-tidal CO2 , was 5.2 ± 0.4 kPa and 5.6 ± 0.4%, respectively, before IHV and 5.1 ± 0.3 kPa and 5.7 ± 0.3%, respectively, during IHV. CONCLUSIONS: In this experimental in vivo model of isocapnic hyperventilation, the washout time of sevoflurane anaesthesia was one-third compared to normal ventilation. The method for isocapnic hyperventilation described can potentially be transferred to a clinical setting with the intention to decrease emergence time from inhalation anaesthesia.

Incidence, clinical presentation and mortality of liver cirrhosis in Southern Sweden: a 10-year population-based study.

BACKGROUND: In Sweden, the most common causes of liver cirrhosis are alcohol overconsumption and hepatitis C. However, recent data on the clinical characteristics of Swedish patients with cirrhosis are scarce. AIMS: To determine the incidence, clinical presentation, aetiological spectrum and survival rates of liver cirrhosis in Southern Sweden from 2001 to 2011. METHODS: We used population-based medical registries to conduct a cohort study of all patients with liver cirrhosis in the southernmost region of Sweden with a population of 1.17 million. Medical records and histopathology data were reviewed. Patients were classified according to aetiology, and clinical parameters were registered. Patients were followed until death or December 2014. RESULTS: A total of 1317 patients with cirrhosis were identified. The crude annual incidence of cirrhosis was estimated at 14.1/100 000. The most common aetiology was alcohol overconsumption with or without additional causes of cirrhosis (58%) followed by HCV alone (13%) and cryptogenic cirrhosis (12%). At diagnosis, ascites occurred in 43%, variceal bleeding in 6% and overt encephalopathy in 4%. The median follow-up was 4.3 years. The total 1-, 5- and 10-year survival rates were 79%, 47% and 27% respectively. Survival rates were better for women than for men. A 10-year cumulative incidence of transplantation was 7.3%. Mortality was worst for alcoholic cirrhosis with concomitant HCV when adjusted for age and gender. CONCLUSIONS: Sweden continues to have a low incidence of cirrhosis compared with other European countries. Mortality varies with gender, aetiology and severity at diagnosis. Patients with alcoholic cirrhosis with concomitant HCV infection fare worst.

A simple method for isocapnic hyperventilation evaluated in a lung model.

BACKGROUND: Isocapnic hyperventilation (IHV) has the potential to increase the elimination rate of anaesthetic gases and has been shown to shorten time to wake-up and post-operative recovery time after inhalation anaesthesia. In this bench test, we describe a technique to achieve isocapnia during hyperventilation (HV) by adding carbon dioxide (CO2) directly to the breathing circuit of a standard anaesthesia apparatus with standard monitoring equipment. METHODS: Into a mechanical lung model, carbon dioxide was added to simulate a CO2 production (V(CO2)) of 175, 200 and 225 ml/min. Dead space (V(D)) volume could be set at 44, 92 and 134 ml. From baseline ventilation (BLV), HV was achieved by doubling the minute ventilation and fresh gas flow for each level of V(CO2), and dead space. During HV, CO2 was delivered (D(CO2)) by a precision flow meter via a mixing box to the inspiratory limb of the anaesthesia circuit to achieve isocapnia. RESULTS: During HV, the alveolar ventilation increased by 113 ± 6%. Tidal volume increased by 20 ± 0.1% during IHV irrespective of V(D) and V(CO2) level. D(CO2) varied between 147 ± 8 and 325 ± 13 ml/min. Low V(CO2) and large V(D) demanded a greater D(CO2) administration to achieve isocapnia. The FICO2 level during IHV varied between 2.3% and 3.3%. CONCLUSION: It is possible to maintain isocapnia during HV by delivering carbon dioxide through a standard anaesthesia circuit equipped with modern monitoring capacities. From alveolar ventilation, CO2 production and dead space, the amount of carbon dioxide that is needed to achieve IHV can be estimated.

Association between high dietary intake of the n-3 polyunsaturated fatty acid docosahexaenoic acid and reduced risk of Crohn's disease.

BACKGROUND: There are plausible mechanisms for how dietary docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, could prevent Crohn's disease (CD). AIM: To conduct a prospective study to investigate the association between increased intake of DHA and risk of CD. METHODS: Overall, 229 702 participants were recruited from nine European centres between 1991 and 1998. At recruitment, dietary intakes of DHA and fatty acids were measured using validated food frequency questionnaires. The cohort was monitored through to June 2004 to identify participants who developed incident CD. In a nested case-control analysis, each case was matched with four controls; odds ratios (ORs) were calculated for quintiles of DHA intake, adjusted for total energy intake, smoking, other dietary fatty acids, dietary vitamin D and body mass index. RESULTS: Seventy-three participants developed incident CD. All higher quintiles of DHA intake were inversely associated with development of CD; the highest quintile had the greatest effect size (OR = 0.07; 95% CI = 0.02-0.81). The OR trend across quintiles of DHA was 0.54 (95% CI = 0.30-0.99, Ptrend  = 0.04). Including BMI in the multivariate analysis, due to its correlation with dietary fat showed similar associations. There were no associations with the other dietary fatty acids studied. CONCLUSION: There were inverse associations, with a biological gradient between increasing dietary docosahexaenoic acid intakes and incident Crohn's disease. Further studies in other populations should measure docosahexaenoic acid to determine if the association is consistent and the hypothesis tested in randomised controlled trials of purely docosahexaenoic acid supplementation.

Clinical guidelines on central venous catheterisation. Swedish Society of Anaesthesiology and Intensive Care Medicine.

Safe and reliable venous access is mandatory in modern health care, but central venous catheters (CVCs) are associated with significant morbidity and mortality, This paper describes current Swedish guidelines for clinical management of CVCs The guidelines supply updated recommendations that may be useful in other countries as well. Literature retrieval in the Cochrane and Pubmed databases, of papers written in English or Swedish and pertaining to CVC management, was done by members of a task force of the Swedish Society of Anaesthesiology and Intensive Care Medicine. Consensus meetings were held throughout the review process to allow all parts of the guidelines to be embraced by all contributors. All of the content was carefully scored according to criteria by the Oxford Centre for Evidence-Based Medicine. We aimed at producing useful and reliable guidelines on bleeding diathesis, vascular approach, ultrasonic guidance, catheter tip positioning, prevention and management of associated trauma and infection, and specific training and follow-up. A structured patient history focused on bleeding should be taken prior to insertion of a CVCs. The right internal jugular vein should primarily be chosen for insertion of a wide-bore CVC. Catheter tip positioning in the right atrium or lower third of the superior caval vein should be verified for long-term use. Ultrasonic guidance should be used for catheterisation by the internal jugular or femoral veins and may also be used for insertion via the subclavian veins or the veins of the upper limb. The operator inserting a CVC should wear cap, mask, and sterile gown and gloves. For long-term intravenous access, tunnelled CVC or subcutaneous venous ports are preferred. Intravenous position of the catheter tip should be verified by clinical or radiological methods after insertion and before each use. Simulator-assisted training of CVC insertion should precede bedside training in patients. Units inserting and managing CVC should have quality assertion programmes for implementation and follow-up of routines, teaching, training and clinical outcome. Clinical guidelines on a wide range of relevant topics have been introduced, based on extensive literature retrieval, to facilitate effective and safe management of CVCs.

The management of iron deficiency in inflammatory bowel disease--an online tool developed by the RAND/UCLA appropriateness method.

BACKGROUND: Iron deficiency is a common and undertreated problem in inflammatory bowel disease (IBD). AIM: To develop an online tool to support treatment choice at the patient-specific level. METHODS: Using the RAND/UCLA Appropriateness Method (RUAM), a European expert panel assessed the appropriateness of treatment regimens for a variety of clinical scenarios in patients with non-anaemic iron deficiency (NAID) and iron deficiency anaemia (IDA). Treatment options included adjustment of IBD medication only, oral iron supplementation, high-/low-dose intravenous (IV) regimens, IV iron plus erythropoietin-stimulating agent (ESA), and blood transfusion. The panel process consisted of two individual rating rounds (1148 treatment indications; 9-point scale) and three plenary discussion meetings. RESULTS: The panel reached agreement on 71% of treatment indications. 'No treatment' was never considered appropriate, and repeat treatment after previous failure was generally discouraged. For 98% of scenarios, at least one treatment was appropriate. Adjustment of IBD medication was deemed appropriate in all patients with active disease. Use of oral iron was mainly considered an option in NAID and mildly anaemic patients without disease activity. IV regimens were often judged appropriate, with high-dose IV iron being the preferred option in 77% of IDA scenarios. Blood transfusion and IV+ESA were indicated in exceptional cases only. CONCLUSIONS: The RUAM revealed high agreement amongst experts on the management of iron deficiency in patients with IBD. High-dose IV iron was more often considered appropriate than other options. To facilitate dissemination of the recommendations, panel outcomes were embedded in an online tool, accessible via http://ferroscope.com/.

Survey of central venous catheterisation practice in Sweden.

BACKGROUND: Clinical guidelines on central venous catheterisation were introduced by the Swedish Society of Anaesthesiology and Intensive Care Medicine in 2011. The purpose of this study was to investigate current national practice and assess to what extent these guidelines influence clinical routines in Swedish operating wards and intensive care units. METHODS: An invitation to participate in an online survey regarding central venous catheterisation was sent to 65 departments of anaesthesiology and intensive care medicine in Sweden. The survey aimed at investigating routine standards (part 1) and 24-h clinical practice (part 2). RESULTS: Forty-seven (72%) and 49 (75%) of 65 departments took part in parts 1 and 2, respectively, and 73% adhered to the national guidelines. Many units monitored mechanical (42%) and infectious (69%) complications. Ultrasound was used by more than 50%. Checklists for insertion were used by 22%. Physicians inserted most catheters. No serious complications were reported during the 24-h study period. Ninety-seven non-tunnelled, 17 venous ports, 9 tunnelled and 8 peripheral central venous catheters were inserted. Ninety-three (71%) catheters were inserted in operating rooms, and 31 (24%) in intensive care units. Catheterisations were followed up by chest X-ray in most departments. CONCLUSION: Knowledge of the Swedish guidelines was adequate, and most participating departments had local catheterisation routines. We could identify some variation in practice, but overall adherence to the guidelines was good. Nevertheless, monitoring of procedures and complications of cannulation and maintenance could be in need of improvement.

Complications associated with peripheral or central routes for central venous cannulation.

We undertook a review of studies comparing complications of centrally or peripherally inserted central venous catheters. Twelve studies were included. Catheter tip malpositioning (9.3% vs 3.4%, p = 0.0007), thrombophlebitis (78 vs 7.5 per 10,000 indwelling days, p = 0.0001) and catheter dysfunction (78 vs 14 per 10,000 indwelling days, p = 0.04) were more common with peripherally inserted catheters than with central catheter placement, respectively. There was no difference in infection rates. We found that the risks of tip malpositioning, thrombophlebitis and catheter dysfunction favour clinical use of centrally placed catheters instead of peripherally inserted central catheters, and that the two catheter types do not differ with respect to catheter-related infection rates.

Fatigue in out-patients with inflammatory bowel disease is common and multifactorial.

BACKGROUND: Patients with inflammatory bowel disease (IBD) often complain of fatigue. AIM: To investigate the prevalence and characteristics of fatigue among IBD out-patients in Scandinavia and to provide normative values for fatigue in IBD patients. METHODS: A cross-sectional study was conducted on 425 IBD patients from six out-patient centres in Denmark, Norway and Sweden. Fatigue was measured using the Multidimensional Fatigue Inventory. The patients were also screened for anaemia and iron deficiency. Each centre included approximately 5% of their IBD cohort. The patients were enrolled consecutively from the out-patient clinics, regardless of disease activity and whether the visit was scheduled. The fatigue analysis was stratified for age and gender. RESULTS: Using the 95th percentile of the score of the general population as a cut-off, approximately 44% of the patients were fatigued. When comparing the IBD patients with disease activity to the IBD patients in remission, all dimensions of fatigue were statistically significant (P < 0.05). Being anaemic or iron deficient was not associated with increased fatigue. Being a male patient with ulcerative colitis treated with corticosteroids was a strong determinant for increased fatigue. The normative ranges for IBD fatigue were calculated. CONCLUSIONS: Fatigue in IBD is common regardless of anaemia or iron deficiency. Fatigue in IBD is most marked for patients < 60 years of age. Stratifying for gender and age is necessary when analysing fatigue, as fatigue is expressed differently between groups.

Oral clefts and behavioral health of young children.

OBJECTIVES: This study examined the behavioral health of young children with oral clefts, and effects of satisfaction with facial appearance, cleft team care, number of cleft-related surgeries, and socioeconomic status (SES). SUBJECTS AND METHODS: The study included a population-based sample of 104 children aged 2-12 years with isolated oral clefts from the state of Iowa. Behavior was evaluated with the Child Behavior Checklist or the Pediatric Behavior Scale 30, depending on age, compared with normative samples. RESULTS: Risks of behavioral problems were not significantly different from normative samples except for higher inattention/hyperactivity risks at age 6-12 years. Low satisfaction with facial appearance was associated with behavioral problems in all domains, except aggression. Team-care effects were not associated with behavioral problems. Number of cleft-related surgeries was associated with increased anxiety/depression and somatic symptom risks. Higher SES was associated with reduced inattention/hyperactivity, aggressive/oppositional behavior, and somatic symptoms. CONCLUSIONS: Most children with oral clefts may have similar behavioral health outcomes to unaffected children, except for increased inattention/hyperactivity risks at older ages. However, low satisfaction with facial appearance, increased exposure to surgeries, and lower SES may significantly increase behavioral problems. Also, the findings emphasize the need to study the representation of behavioral health professionals on cleft teams and access to behavioral health care.

Positive end-expiratory pressure-induced changes in end-expiratory lung volume measured by spirometry and electric impedance tomography.

BACKGROUND: A bedside tool for monitoring changes in end-expiratory lung volume (ΔEELV) would be helpful to set optimal positive end-expiratory pressure (PEEP) in acute lung injury/acute respiratory distress syndrome patients. The hypothesis of this study was that the cumulative difference of the inspiratory and expiratory tidal volumes of the first 10 breaths after a PEEP change accurately reflects the change in lung volume following a PEEP alteration. METHODS: Changing PEEP induces lung volume changes, which are reflected in differences between inspiratory and expiratory tidal volumes measured by spirometry. By adding these differences with correction for offset, for the first 10 breaths after PEEP change, cumulative tidal volume difference was calculated to estimate ΔEELV(VT) ((i-e)) . This method was evaluated in a lung model and in patients with acute respiratory failure during a PEEP trial. In patients, ΔEELV(VT) ((i-e)) were compared with simultaneously measured changes in lung impedance, by electric impedance tomography (EIT), using calibration vs. tidal volume to estimate changes in ΔEELV(EIT) . RESULTS: In the lung model, there was close correlation (R(2) = 0.99) between ΔEELV(VT) ((i-e)) and known lung model volume difference, with a bias of -4 ml and limits of agreement of 42 and -50 ml. In 12 patients, ΔEELV(EIT) was closely correlated to ΔEELV(VT) ((i-e)) (R(2) = 0.92), with mean bias of 50 ml and limits of agreement of 131 and -31 ml. Changes in EELV estimated by EIT (ΔEELV(EIT) ) exceeded measurements by spirometry (ΔEELV(VT) ((i-e)) ), with 15 (±15)%. CONCLUSIONS: We conclude that spirometric measurements of inspiratory-expiratory tidal volumes agree well with impedance changes monitored by EIT and can be used bedside to estimate PEEP-induced changes in EELV.

Prolonged moderate pressure recruitment manoeuvre results in lower optimal positive end-expiratory pressure and plateau pressure.

BACKGROUND: In acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), recruitment manoeuvres (RMs) are used frequently. In pigs with induced ALI, superior effects have been found using a slow moderate-pressure recruitment manoeuvre (SLRM) compared with a vital capacity recruitment manoeuvre (VICM). We hypothesized that the positive recruitment effects of SLRM could also be achieved in ALI/ARDS patients. Our primary research question was whether the same compliance could be obtained using lower RM pressure and subsequent positive end-expiratory pressure (PEEP). Secondly, optimal PEEP levels following the RMs were compared, and the use of volume-dependent compliance (VDC) to identify successful lung recruitment and optimal PEEP was evaluated. PATIENTS AND METHODS: We performed a prospective randomised cross-over study where 16 ventilated patients with early ALI/ARDS each were subjected to the two RMs, followed by decremental PEEP titration. Volume-dependent initial, middle and final compliance (C(ini) , C(mid) and C(fin) ) were determined. Electric impedance tomography and end-expiratory lung volume measurements were used to follow lung volume changes. RESULTS: The maximum response in compliance, PaO2/FIO2, venous admixture and C(ini) /C(fin) after recruitment, during decremental PEEP, was at significantly lower PEEP and plateau pressure after SLRM than VICM. Fewer patients responded in gas exchange after the SLRM, which was not the case for lung mechanics. The response in C(ini) was more pronounced than in conventional compliance. CONCLUSIONS: The same compliance increase is achieved with SLRM as with VICM, and lower PEEP can be used, with correspondingly lower plateau pressures. VDC seems promising to identify successful recruitment and optimal PEEP.

A new non-radiological method to assess potential lung recruitability: a pilot study in ALI patients.

INTRODUCTION: Potentially recruitable lung has been assessed previously in patients with acute lung injury (ALI) by computed tomography. A large variability in lung recruitability was observed between patients. In this study, we assess whether a new non-radiological bedside technique could determine potentially recruitable lung volume (PRLV) in ALI patients. METHODS: Sixteen mechanically ventilated patients with early ALI/ARDS were subjected to a recruitment manoeuvre and decremental PEEP titration. Electric impedance tomography, together with measurements of end-expiratory lung volume (EELV) and tracheal pressure, were used to determine PRLV. The method defines fully recruited open lung volume (OLV) as the volume reached at the end of two consecutive vital capacity manoeuvres to 40 cmH2O. It also uses extrapolation of the baseline alveolar pressure/volume curve up to 40 cmH2O, the volume reached being the non-recruited lung volume. The difference between the fully recruited and the non-recruited volume was defined as PRLV. RESULTS: We observed a considerable heterogeneity among the patients in lung recruitability, PRLV range 11-47%. In a post hoc analysis, dividing the patients into two groups, a high and a low PRLV group, we found at baseline before the recruitment manoeuvre that the high PRLV group had lower compliance and a lower fraction of EELV/OLV. CONCLUSIONS: Using non-invasive radiation-free bedside methods, it may be possible to measure PRLV in ALI/ARDS patients. It is possible that this technique could be used to determine the need for recruitment manoeuvres and to select PEEP level on the basis of lung recruitability.

End-expiratory lung volume and ventilation distribution with different continuous positive airway pressure systems in volunteers.

BACKGROUND: Continuous positive airway pressure (CPAP) has been shown to improve oxygenation and a number of different CPAP systems are available. The aim of this study was to assess lung volume and ventilation distribution using three different CPAP techniques. METHODS: A high-flow CPAP system (HF-CPAP), an ejector-driven system (E-CPAP) and CPAP using a Servo 300 ventilator (V-CPAP) were randomly applied at 0, 5 and 10 cmH2O in 14 volunteers. End-expiratory lung volume (EELV) was measured by N2 dilution at baseline; changes in EELV and tidal volume distribution were assessed by electric impedance tomography. RESULTS: Higher end-expiratory and mean airway pressures were found using the E-CPAP vs. the HF-CPAP and the V-CPAP system (P<0.01). EELV increased markedly from baseline, 0 cmH2O, with increased CPAP levels: 1110±380, 1620±520 and 1130±350 ml for HF-, E- and V-CPAP, respectively, at 10 cmH2O. A larger fraction of the increase in EELV occurred for all systems in ventral compared with dorsal regions (P<0.01). In contrast, tidal ventilation was increasingly directed toward dorsal regions with increasing CPAP levels (P<0.01). The increase in EELV as well as the tidal volume redistribution were more pronounced with the E-CPAP system as compared with both the HF-CPAP and the V-CPAP systems (P<0.05) at 10 cmH2O. CONCLUSION: EELV increased more in ventral regions with increasing CPAP levels, independent of systems, leading to a redistribution of tidal ventilation toward dorsal regions. Different CPAP systems resulted in different airway pressure profiles, which may result in different lung volume expansion and tidal volume distribution.