Automatic selection of tidal volume, respiratory frequency and minute ventilation in intubated ICU patients as start up procedure for closed-loop controlled ventilation.

OBJECTIVE: Before a patient can be connected to a mechanical ventilator, the controls of the apparatus need to be set up appropriately. Today, this is done by the intensive care professional. With the advent of closed loop controlled mechanical ventilation, methods will be needed to select appropriate start up settings automatically. The objective of our study was to test such a computerized method which could eventually be used as a start-up procedure (first 5-10 minutes of ventilation) for closed-loop controlled ventilation. DESIGN: Prospective Study. SETTINGS: ICU's in two adult and one children's hospital. PATIENTS: 25 critically ill adult patients (age > or = 15 y) and 17 critically ill children selected at random were studied. INTERVENTIONS: To stimulate 'initial connection', the patients were disconnected from their ventilator and transiently connected to a modified Hamilton AMADEUS ventilator for maximally one minute. During that time they were ventilated with a fixed and standardized breath pattern (Test Breaths) based on pressure controlled synchronized intermittent mandatory ventilation (PCSIMV). MEASUREMENTS AND MAIN RESULTS: Measurements of airway flow, airway pressure and instantaneous CO2 concentration using a mainstream CO2 analyzer were made at the mouth during application of the Test-Breaths. Test-Breaths were analyzed in terms of tidal volume, expiratory time constant and series dead space. Using this data an initial ventilation pattern consisting of respiratory frequency and tidal volume was calculated. This ventilation pattern was compared to the one measured prior to the onset of the study using a two-tailed paired t-test. Additionally, it was compared to a conventional method for setting up ventilators. The computer-proposed ventilation pattern did not differ significantly from the actual pattern (p > 0.05), while the conventional method did. However the scatter was large and in 6 cases deviations in the minute ventilation of more than 50% were observed. CONCLUSIONS: The analysis of standardized Test Breaths allows automatic determination of an initial ventilation pattern for intubated ICU patients. While this pattern does not seem to be superior to the one chosen by the conventional method, it is derived fully automatically and without need for manual patient data entry such as weight or height. This makes the method potentially useful as a start up procedure for closed-loop controlled ventilation.

Complications of different ventilation strategies in endoscopic laryngeal surgery: a 10-year review.

BACKGROUND: Spontaneous ventilation, mechanical controlled ventilation, apneic intermittent ventilation, and jet ventilation are commonly used during interventional suspension microlaryngoscopy. The aim of this study was to investigate specific complications of each technique, with special emphasis on transtracheal and transglottal jet ventilation. METHODS: The authors performed a retrospective single-institution analysis of a case series of 1,093 microlaryngoscopies performed in 661 patients between January 1994 and January 2004. Data were collected from two separate prospective databases. Feasibility and complications encountered with each technique of ventilation were analyzed as main outcome measures. RESULTS: During 1,093 suspension microlaryngoscopies, ventilation was supplied by mechanical controlled ventilation via small endotracheal tubes (n = 200), intermittent apneic ventilation (n = 159), transtracheal jet ventilation (n = 265), or transglottal jet ventilation (n = 469). Twenty-nine minor and 4 major complications occurred. Seventy-five percent of the patients with major events had an American Society of Anesthesiologists physical status classification of III. Five laryngospasms were observed with apneic intermittent ventilation. All other 24 complications (including 7 barotrauma) occurred during jet ventilation. Transtracheal jet ventilation was associated with a significantly higher complication rate than transglottal jet ventilation (P < 0.0001; odds ratio, 4.3 [95% confidence interval, 1.9-10.0]). All severe complications were related to barotraumas resulting from airway outflow obstruction during jet ventilation, most often laryngospasms. CONCLUSIONS: The use of a transtracheal cannula was the major independent risk factor for complications during jet ventilation for interventional microlaryngoscopy. The anesthetist's vigilance in clinically detecting and preventing outflow airway obstruction remains the best prevention of barotrauma during subglottic jet ventilation.

Overspeed HIIT in Lower-Body Positive Pressure Treadmill Improves Running Performance.

PURPOSE: Optimal high-intensity interval training (HIIT) regimens for running performance are unknown, although most protocols result in some benefit to key performance factors (running economy (RE), anaerobic threshold (AT), or maximal oxygen uptake (V˙O2max)). Lower-body positive pressure (LBPP) treadmills offer the unique possibility to partially unload runners and reach supramaximal speeds. We studied the use of LBPP to test an overspeed HIIT protocol in trained runners. METHODS: Eleven trained runners (35 ± 8 yr, V˙O2max, 55.7 ± 6.4 mL·kg·min) were randomized to an LBPP (n = 6) or a regular treadmill (CON, n = 5), eight sessions over 4 wk of HIIT program. Four to five intervals were run at 100% of velocity at V˙O2max (vV˙O2max) during 60% of time to exhaustion at vV˙O2max (Tlim) with a 1:1 work:recovery ratio. Performance outcomes were 2-mile track time trial, V˙O2max, vV˙O2max, vAT, Tlim, and RE. LBPP sessions were carried out at 90% body weight. RESULTS: Group-time effects were present for vV˙O2max (CON, 17.5 vs. 18.3, P = 0.03; LBPP, 19.7 vs. 22.3 km·h; P < 0.001) and Tlim (CON, 307.0 vs. 404.4 s, P = 0.28; LBPP, 444.5 vs. 855.5, P < 0.001). Simple main effects for time were present for field performance (CON, -18; LBPP, -25 s; P = 0.002), V˙O2max (CON, 57.6 vs. 59.6; LBPP, 54.1 vs. 55.1 mL·kg·min; P = 0.04) and submaximal HR (157.7 vs. 154.3 and 151.4 vs. 148.5 bpm; P = 0.002). RE was unchanged. CONCLUSIONS: A 4-wk HIIT protocol at 100% vV˙O2max improves field performance, vV˙O2max, V˙O2max and submaximal HR in trained runners. Improvements are similar if intervals are run on a regular treadmill or at higher speeds on a LPBB treadmill with 10% body weight reduction. LBPP could provide an alternative for taxing HIIT sessions.

The effects of 2 levels of the inspired oxygen fraction on blood gas variables in propofol-anesthetized dogs with high intracranial pressure

The influence of 2 different levels of the inspired oxygen fraction (FiO(2)) on blood gas variables was evaluated in dogs with high intracranial pressure (ICP) during propofol anesthesia (induction followed by a continuous rate infusion [CRI] of 0.6 mg/kg/min) and intermittent positive pressure ventilation (IPPV). Eight adult mongrel dogs were anesthetized on 2 occasions, 21 d apart, and received oxygen at an FiO(2) of 1.0 (G100) or 0.6 (G60) in a randomized crossover fashion. A fiberoptic catheter was implanted on the surface of the right cerebral cortex for assessment of the ICP. An increase in the ICP was induced by temporary ligation of the jugular vein 50 min after induction of anesthesia and immediately after baseline measurement of the ICP. Blood gas measurements were taken 20 min later and then at 15-min intervals for 1 h. Numerical data were submitted to Morrison's multivariate statistical methods. The ICP, the cerebral perfusion pressure and the mean arterial pressure did not differ significantly between FiO(2) levels or measurement times after jugular ligation. The only blood gas values that differed significantly (P < 0.05) were the arterial oxygen partial pressure, which was greater with G100 than with G60 throughout the procedure, and the venous haemoglobin saturation, that was greater with G100 than with G60 at M0. There were no significant differences between FiO(2) levels or measurement times in the following blood gas variables: arterial carbon dioxide partial pressure, arterial hemoglobin saturation, base deficit, bicarbonate concentration, pH, venous oxygen partial pressure, venous carbon dioxide partial pressure and the arterial-to-end-tidal carbon dioxide difference.

Ventilação mecânica não-invasiva no pós-operatório de cirurgia cardíaca: atualização da literatura

Este estudo objetivou atualizar os conhecimentos em relação à utilização da ventilação mecânica não-invasiva (VMNI) no pós-operatório de cirurgia cardíaca e identificar se há indícios da superioridade de uma forma de modalidade de VMNI em relação à outra. Foi realizada revisão da literatura entre 2006 a 2011, a partir das bases de dados PubMed, SciELO e Lilacs, utilizando os descritores respiração artificial, pressão positiva contínua nas vias aéreas, ventilação com pressão positiva intermitente e cirurgia cardíaca, e seus correspondentes na língua inglesa, os quais foram pesquisados em cruzamentos. A partir dos critérios adotados, foram selecionados nove artigos, dos quais seis demonstraram aplicações de VMNI, por meio de modalidades como pressão positiva contínua nas vias aéreas, pressão positiva com dois níveis pressóricos e respiração com pressão positiva intermitente, no pós-operatório de cirurgia cardíaca, e, três realizaram comparações entre as diferentes modalidades. As modalidades de VMNI descritas na literatura foram utilizadas com resultados satisfatórios. Estudos que comparam diferentes modalidades são escassos, contudo alguns demonstraram superioridade de uma modalidade de VMNI, como é o caso da respiração com pressão positiva intermitente na reversão da hipoxemia e da pressão positiva com dois níveis pressóricos na melhora da oxigenação, da frequência respiratória e frequência cardíaca desses pacientes, em comparação a outras modalidades.

Comparison of 3 modes of automated weaning from mechanical ventilation: A bench study

Purpose: Automated weaning modes are available in some mechanical ventilators, but no studies compared them hitherto. We compared the performance of 3 automated modes under standard and challenging situations. Methods: We used a lung simulator to compare 3 automated modes, adaptive support ventilation (ASV), mandatory rate ventilation (MRV), and Smartcare, in 6 situations, weaning success, weaning failure, weaning success with extreme anxiety, weaning success with Cheyne-Stokes, weaning success with irregular breathing, and weaning failure with ineffective efforts. Results: The 3 modes correctly recognized the situations of weaning success and failure, even when anxiety or irregular breathing were present but incorrectly recognized weaning success with Cheyne-Stokes. MRV incorrectly recognized weaning failure with ineffective efforts. Time to pressure support (PS) stabilization was shorter for ASV (1-2 minutes for all situations) and MRV (1-7 minutes) than for Smartcare (8-78 minutes). ASV had higher rates of PS oscillations per 5 minutes (4-15), compared with Smartcare (0-1) and MRV (0-12), except when extreme anxiety was present. Conclusions: Smartcare, ASV, and MRV were equally able to recognize weaning success and failure, despite the presence of anxiety or irregular breathing but performed incorrectly in the presence of Cheyne-Stokes. PS behavior over the time differs among modes, with ASV showing larger and more frequent PS oscillations over the time. Clinical studies are needed to confirm our results. (C) 2012 Elsevier Inc. All rights reserved.

Noninvasive 4D pressure difference mapping derived from 4D flow MRI in patients with repaired aortic coarctation: comparison with young healthy volunteers

To assess spatial and temporal pressure characteristics in patients with repaired aortic coarctation compared to young healthy volunteers using time-resolved velocity-encoded three-dimensional phase-contrast magnetic resonance imaging (4D flow MRI) and derived 4D pressure difference maps. After in vitro validation against invasive catheterization as gold standard, 4D flow MRI of the thoracic aorta was performed at 1.5T in 13 consecutive patients after aortic coarctation repair without recoarctation and 13 healthy volunteers. Using in-house developed processing software, 4D pressure difference maps were computed based on the Navier-Stokes equation. Pressure difference amplitudes, maximum slope of pressure amplitudes and spatial pressure range at mid systole were retrospectively measured by three readers, and twice by one reader to assess inter- and intraobserver agreement. In vitro, pressure differences derived from 4D flow MRI showed excellent agreement to invasive catheter measurements. In vivo, pressure difference amplitudes, maximum slope of pressure difference amplitudes and spatial pressure range at mid systole were significantly increased in patients compared to volunteers in the aortic arch, the proximal descending and the distal descending thoracic aorta (p < 0.05). Greatest differences occurred in the proximal descending aorta with values of the three parameters for patients versus volunteers being 19.7 ± 7.5 versus 10.0 ± 2.0 (p < 0.001), 10.9 ± 10.4 versus 1.9 ± 0.4 (p = 0.002), and 8.7 ± 6.3 versus 1.6 ± 0.9 (p < 0.001). Inter- and intraobserver agreements were excellent (p < 0.001). Noninvasive 4D pressure difference mapping derived from 4D flow MRI enables detection of altered intraluminal aortic pressures and showed significant spatial and temporal changes in patients with repaired aortic coarctation.

Less invasive ventilation in extremely low birth weight infants from 1997 to 2011: survey versus evidence.

UNLABELLED Evidence for target values of arterial oxygen saturation (SaO2), CO2, and pH has changed substantially over the last 20 years. A representative survey concerning treatment strategies in extremely low-birth-weight infants (ELBW) was sent to all German neonatal intensive care units (NICUs) treating ELBW infants in 1997. A follow-up survey was conducted in 2011 and sent to all NICUs in Germany, Austria, and Switzerland. During the observation period, NICUs targeting SaO2 of 80, 85, and 90 % have increased, while units aiming for 94 and 96 % decreased (all p < 0.001). Similarly, NICUs aiming for pH 7.25 or lower increased, while 7.35 or higher decreased (both p < 0.001). Furthermore, more units targeted a CO2 of 50 mmHg (7.3 kPa) or higher (p < 0.001), while fewer targeted 40 or 35 mmHg (p < 0.001). Non-invasive ventilation (NIV) was used in 80.2 % of NICUs in 2011. The most frequently used ventilation modes were synchronized intermittent mandatory ventilation (SIMV) (67.5 %) and intermittent positive pressure ventilation (IPPV) (59.7 %) in 1997 and SIMV (77.2 %) and synchronized intermittent positive pressure ventilation (SIPPV) (26.8 %) in 2011. NICUs reporting frequent or always use of IPPV decreased to 11.0 % (p < 0.001). SIMV (77.2 %) and SIPPV (26.8 %) did not change from 1997 to 2011, while high-frequency oscillation (HFO) increased from 9.1 to 19.7 % (p = 0.018). Differences between countries, level of care, and size of the NICU were minimal. CONCLUSIONS Target values for SaO2 decreased, while CO2 and pH increased significantly during the observation period. Current values largely reflect available evidence at time of the surveys. WHAT IS KNOWN • Evidence concerning target values of oxygen saturation, CO 2 , and pH in extremely low-birth-weight infants has grown substantially. • It is not known to which extent this knowledge is transferred into clinical practice and if treatment strategies have changed. WHAT IS NEW • Target values for oxygen saturation in ELBW infants decreased between 1997 and 2011 while target values for CO 2 and pH increased. • Similar treatment strategies existed in different countries, hospitals of different size, or university versus nonuniversity hospitals in 2011.

Sleep-related breathing disorder in Duchenne muscular dystrophy: Disease spectrum in the paediatric population

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease with death usually occurring because of respiratory failure. Signs of early respiratory insufficiency are usually first detectable in sleep. Objective: To study the presentation of sleep-related breathing disorder (SRBD) in patients with DMD. Method:> A retrospective review of patients with DMD attending a tertiary paediatric sleep disorder clinic over a 5-year period. Symptoms, lung function and polysomnographic indices were reviewed. Results: A total of 34 patients with DMD were referred for respiratory assessment (1-15 years). Twenty-two (64%) reported sleep-related symptomatology. Forced vital capacity (FVC) was between 12 and 107% predicted (n = 29). Thirty-two progressed to have polysomnography of which 15 were normal studies (median age: 10 years) and 10 (31%) were diagnostic of obstructive sleep apnoea (OSA) (median age: 8 years). A total of 11 patients (32%) showed hypoventilation (median age: 13 years) during the 5-year period and non-invasive ventilation (NIV) was offered to them. The median FVC of this group was 27% predicted. There was a significant improvement in the apnoea/hypopnoea index (AHI) (mean difference = 11.31, 95% CI = 5.91-16.70, P = 0.001) following the institution of NIV. Conclusions: The prevalence of SRBD in DMD is significant. There is a bimodal presentation of SRBD, with OSA found in the first decade and hypoventilation more commonly seen at the beginning of the second decade. Polysomnography is recommended in children with symptoms of OSA, or at the stage of becoming wheelchair-bound. In patients with the early stages of respiratory failure, assessment with polysomnography-identified sleep hypoventilation and assisted in initiating NIV.

Effect of manual hyperinflation on hemodynamics, gas exchange, and respiratory mechanics in ventilated patients

The authors investigated the effect of manual hyperinflation (MHI) with set parameters applied to patients on mechanical ventilation on hemodynamics, respiratory mechanics, and gas exchange. Sixteen critically ill patients post-septic shock, with acute lung injury, were studied. Heart rate, arterial pressure, and mean pulmonary artery pressure were recorded every minute. pulmonary artery occlusion pressure, cardiac output, arterial blood gases, and dynamic compliance (C-dyn) were recorded pre- and post-MHI. From this, systemic vascular resistance index (SVRI), cardiac index, oxygen delivery, and partial pressure of oxygen:fraction of inspired oxygen (PaO2:FiO(2)) ratio were calculated. There were significant increases in SVRI (P < 0.05) post-MHI and diastolic arterial pressure (P < 0.01)during MHI. C-dyn increased post-MHI (P < 0.01) and was sustained at 20 minutes post-MHI (P < 0.01). Subjects with an intrapulmonary cause of lung disease had a significant decrease (P = 0.02) in PaO2:FiO(2), and those with extrapulmonary causes of lung disease had a significant increase (P < 0.001) in PaO2:FiO(2) post-MHI. In critically ill patients, MHI resulted in an improvement in lung mechanics and an improvement in gas exchange in patients with lung disease due to extrapulmonary events and did not result in impairment of the cardiovascular system.

Intratracheal suctioning in sick preterm infants: prevention of intracranial hypertension and cerebral hypoperfusion by muscle paralysis.

In a prospective nonrandomized study, using each baby as his or her own control, we compared intracranial pressure (anterior fontanel pressure as measured with the Digilab pneumotonometer), cerebral perfusion pressure, BP, heart rate, transcutaneous Po2, and transcutaneous Pco2 before, during, and after endotracheal suctioning, with and without muscle paralysis, in 28 critically ill preterm infants with respiratory distress syndrome. With suctioning, there was a small but significant increase in intracranial pressure in paralyzed patients (from 13.7 [mean] +/- 4.4 mm Hg [SD] to 15.8 +/- 5.2 mm Hg) but a significantly larger (P less than .001) increase when they were not paralyzed (from 12.5 +/- 3.6 to 28.5 +/- 8.3 mm Hg). Suctioning led to a slight increase in BP with (from 45.3 +/- 9.1 to 48.0 +/- 8.7 mm Hg) and without muscle paralysis (from 45.1 +/- 9.4 to 50.0 +/- 11.7 mm Hg); but there was no significant difference between the two groups. The cerebral perfusion pressure in paralyzed infants did not show any significant change before, during, and after suctioning (31.5 +/- 9.1 mm Hg before v 32.0 +/- 8.7 mm Hg during suctioning), but without muscle paralysis cerebral perfusion pressure decreased (P less than .001) from 32.8 +/- 9.7 to 21.3 +/- 13.1 mm Hg. Suctioning induced a slight decrease in mean heart rate and transcutaneous Po2, but pancuronium did not alter these changes. There was no statistical difference in transcutaneous Pco2 before, during, and after suctioning with and without muscle paralysis.(ABSTRACT TRUNCATED AT 250 WORDS)

EFNS guidelines on the clinical management of amyotrophic lateral sclerosis (MALS)--revised report of an EFNS task force.

BACKGROUND: The evidence base for the diagnosis and management of amyotrophic lateral sclerosis (ALS) is weak. OBJECTIVES: To provide evidence-based or expert recommendations for the diagnosis and management of ALS based on a literature search and the consensus of an expert panel. METHODS: All available medical reference systems were searched, and original papers, meta-analyses, review papers, book chapters and guidelines recommendations were reviewed. The final literature search was performed in February 2011. Recommendations were reached by consensus. RECOMMENDATIONS: Patients with symptoms suggestive of ALS should be assessed as soon as possible by an experienced neurologist. Early diagnosis should be pursued, and investigations, including neurophysiology, performed with a high priority. The patient should be informed of the diagnosis by a consultant with a good knowledge of the patient and the disease. Following diagnosis, the patient and relatives/carers should receive regular support from a multidisciplinary care team. Medication with riluzole should be initiated as early as possible. Control of symptoms such as sialorrhoea, thick mucus, emotional lability, cramps, spasticity and pain should be attempted. Percutaneous endoscopic gastrostomy feeding improves nutrition and quality of life, and gastrostomy tubes should be placed before respiratory insufficiency develops. Non-invasive positive-pressure ventilation also improves survival and quality of life. Maintaining the patient's ability to communicate is essential. During the entire course of the disease, every effort should be made to maintain patient autonomy. Advance directives for palliative end-of-life care should be discussed early with the patient and carers, respecting the patient's social and cultural background.

Respiratory distress in a one-month-old child suffering brachial plexus palsy.

This paper describes a one-month-old girl presenting with respiratory and growth failure due to diaphragmatic paralysis associated with left brachial plexus palsy after forceps delivery. Despite continuous positive pressure ventilation and nasogastric feeding, the situation did not improve and a laparoscopic diaphragmatic plication had to be performed. When dealing with a child born with brachial plexus palsy, one must think of this possible association and if necessary proceed to the complementary radiological examinations. The treatment must avoid complications like feeding difficulties and failure to thrive, respiratory infections or atelectasis. It includes intensive support and a good evaluation of the prognosis of the lesion to decide the best moment for a surgical therapy.

The use of infrared thermography in the identification of pododermatitis in broilers

ABSTRACT International trade in broiler’ feet, mainly to Asian markets, has demanded better quality control. The objective of this research was to study the suitability of using chicken footpad surface temperature to determine early lesions of pododermatitis. The project was conducted in two houses A1 and A2) in a commercial farm during one production flock. A1 had reused litter of wood shavings and rice hulls, and A2 had a new litter of sawdust. Both houses had positive pressure ventilation. The inner area of the poultry was virtually divided into three quadrants. The footpads were checked for the feet quality, and a degree of pododermatitis was awarded. Thermal images were made to test the surface temperature of the foot and identify inflammation in a total of 30 birds per house, at ages 5, 19, 29, 28 and 40 days of grow-out. Conditions of the rearing environment as well as the surface temperature of the litter, litter moisture, and degree of compression, were recorded. The environment within the houses did not differ. The surface temperatures of the footpad did not differ between the groups. The minimum footpad surface temperatures within the scores were similar, except for the score 3, which did not occur in A1. There was a prevalence of severe injury in the house with a new litter.

Edema pulmonar de reexpansão tratado com ventilação não invasiva: relato de caso

The authors report a case of Reexpansion Pulmonary Edema (RPE) seen at Hospital de Pronto Socorro de Porto Alegre 3 hours after drainage of spontaneous pneumothorax. The patient presented a unilateral pneumothorax with one-week duration. After pleural drainage respiratory failure occured being managed at the Intensive Care Unit with non-invasive positive pressure ventilation through facial mask. The patient had favorable outcome and was discharged asymtomatic after 72 hours.