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PubMedDate not supplied

High frequency ventilator therapy for newborns.

High-frequency ventilation is a general term that refers to a family of ventilator techniques that utilize respirator rates greater than 60 breaths/minute and tidal volumes that are usually less than or equal to the anatomical dead space of the airways. These techniques include high frequency positive-pressure ventilation, high frequency jet ventilation, high frequency flow interruption, high frequency oscillatory ventilation, and high frequency chest wall oscillation. I review the proposed mechanisms of gas transport during high-frequency ventilation and the different ventilators capable of delivering this mode of ventilation. In addition, clinical studies involving infants treated with this new technology are reviewed, along with long-term patient follow-up and reported complications.

Animals↗
PubMed1996

Utilizing quality assurance as a tool for reducing the risk of nosocomial ventilator-associated pneumonia.

A multidisciplinary group was formed to develop strategies to reduce ventilator-associated lower respiratory tract infections (LRI) in an intensive care unit (ICU) of a 540-bed acute care teaching medical center. The group process was facilitated by the Infection Director and the quality management specialist. The group was made of medical, nursing, and respiratory therapy staff. Quality improvement techniques were used to define the process of care for ventilated patients in the ICU. "State of the art" care was defined after a literature review and brainstorming sessions. Current practice and new concepts were then forged into a realistic protocol for the ICU. The resulting protocol was introduced into the ICU in May 1992. The information was communicated to Respiratory Therapy and ICU staff in writing and at department meetings. After a 4-month introductory period and learning curve process, a decrease in the endemic rate of ventilator-associated LRI was reduced in the fourth quarter of 1992. The mean 1993 LRI rate was 21 LRI/1000 ventilator days versus 26 LRI/1000 ventilator days in 1992 before protocol implementation. This equates to 18 LRI prevented in 1993. This represents a savings of $126,000. There was a significant decrease in the process variation of the monthly mean LRI/1000 ventilator days in 1993 from 1992. To date, there continues to be improvement with a mean of 16 LRI/1000 ventilator days reported in 1994. The ICU staff developed a multidisciplinary process evaluation and monitored staff implementation of the protocol over time. The results of the evaluation were used as feedback to measure protocol implementation. This was found to improve compliance with the protocol. Both the process (care of ventilated patients) and the outcome (number of LRI) have been improved through use of continuous quality improvement concepts and transdisciplinary interventions.

Clinical Protocols↗
PubMed2001

Pulmonary ventilation imaged by magnetic resonance: at the doorstep of clinical application.

Over the past few years, magnetic resonance imaging (MRI) has emerged as an important instrument for functional ventilation imaging. The aim of this review is to summarize established clinical methods and emerging techniques for research and clinical arenas. Before the advent of MRI, chest radiography and computed tomography (CT) dominated morphological lung imaging, while functional ventilation imaging was accomplished with scintigraphy. Initially, MRI was not used for morphological lung imaging often, due to technical and physical limitations. However, recent developments have considerably improved anatomical MRI, as well as advanced new techniques in functional ventilation imaging, such as inhaled contrast aerosols, oxygen, hyperpolarized noble gases (Helium-3, Xenon-129), and fluorinated gases (sulphur-hexafluoride). Straightforward images demonstrating homogeneity of ventilation and determining ventilated lung volumes can be obtained. Furthermore, new image-derived functional parameters are measurable, such as airspace size, regional oxygen partial pressure, and analysis of ventilation distribution and ventilation/perfusion ratios. There are several advantages to using MRI: lack of radiation, high spatial and temporal resolution and a broad range of functional information. The MRI technique applied in patients with chronic obstructive pulmonary disease, emphysema, cystic fibrosis, asthma, and bronchiolitis obliterans, may yield a higher sensitivity in the detection of ventilation defects than ventilation scintigraphy, CT or standard pulmonary function tests. The next step will be to define the threshold between physiological variation and pathological defects. Using complementary strategies, radiologists will have the tools to characterize the impairment of lung function and to improve specificity.

Animals↗
PubMed2006

Safety and feasibility of exhaled breath condensate collection in ventilated infants and children.

The aim of this study was to develop a technique for the collection of exhaled breath condensate (EBC) from ventilated children and assess its safety and feasibility. Collection of EBC is used to investigate markers of oxidative stress in the lower airway. No studies have assessed its safety in ventilated children. An in vitro model was developed by connecting a ventilator to an artificial lung; 14 clinical and ventilatory parameters were measured during EBC collection from ventilated children. Levels of 8-isoprostane were measured following collection with and without humidification of the inhaled gas. Amount of water vapour collected was linearly related to time and to minute ventilation in the in vitro model. EBC collections (n = 68) were made from ventilated children. In the nonhumidified group, the mean (range) positive end-expiratory pressure increased by 4.1% (2.8-5.5%) and the peak inspiratory flow decreased by 6.1% (11.0-1.3%) during collection. Detectable levels of 8-isoprostane were only found in 10 out of 18 nonhumidified EBC samples (median (range) 4.7 pg x mL(-1) (0-5.8)). Collection of exhaled breath condensate from ventilated infants and children is feasible and safe. Discontinuation of humidification is likely to be important in standardising the measurement of inflammatory parameters in exhaled breath condensate collected from ventilated children.

Air↗
PubMed1998

Noninvasive pressure support ventilation in COPD patients with postextubation hypercapnic respiratory insufficiency.

Patients with chronic obstructive pulmonary disease (COPD) who have been intubated and mechanically ventilated may prove difficult to wean. Noninvasive ventilation may be used in an attempt to avoid new endotracheal intubation. The efficacy of administration of noninvasive pressure support ventilation was evaluated in 30 COPD patients with postextubation hypercapnic respiratory insufficiency, compared with 30 historically matched control patients who were treated conventionally. Patients were included in the study if, within 72 h postextubation, they presented with respiratory distress, defined as the combination of a respiratory frequency >25 breaths x min(-1), an increase in the arterial carbon dioxide tension (Pa,CO2) of at least 20% compared with the value measured after extubation, and a pH <7.35. Noninvasive pressure support ventilation was effective in correcting gas exchange abnormalities. The use of noninvasive ventilation significantly reduced the need for endotracheal intubation: 20 of the 30 patients (67%) in the control group required endotracheal intubation, compared with only six of the 30 patients (20%) in the noninvasive-ventilation group (p<0.001). In-hospital mortality was not significantly different between the two groups, but the mean duration of ventilatory assistance for the treatment of the postextubation distress, and the length of intensive care unit stay related to this event, were both significantly shortened by noninvasive ventilation (p<0.01). In conclusion, noninvasive ventilation may be used in the management of patients with chronic obstructive pulmonary disease and postextubation hypercapnic respiratory insufficiency.

Aged↗
PubMed1997

Human and financial costs of noninvasive mechanical ventilation in patients affected by COPD and acute respiratory failure.

STUDY OBJECTIVES: It has been suggested that noninvasive mechanical ventilation (NIMV) may be a time-consuming procedure for medical and paramedical personnel. We carried out a prospective trial in 10 consecutive COPD patients aimed at assessing the human and economic resources needed to ventilate patients by NIMV and we compared these with those needed by a group of six patients receiving invasive mechanical ventilation (InMV). DESIGN: The daily cost and the minutes spent by medical doctors (MDs), respiratory therapists (RTs), and nurses (Ns) were recorded during the first 48 h of ventilation in 10 patients during NIMV (group A) and in six who received InMV (group B) after an initial unsuccessful attempt with NIMV. In two subgroups of patients (five for group A and four for group B), the analysis was also performed, except for RTs, for the total length of mechanical ventilation. SETTING: A respiratory ICU. PATIENTS: At hospital admission, the two groups of COPD patients did not differ for blood gas values (PaCO2 = 88.2+/-9.8 mm Hg for group A vs 90.5+/-12.8 mm Hg for group B, and pH = 7.21+0.08 vs 7.20+0.08, respectively) or for clinical and neurologic status, but patients of group B had not tolerated NIMV. MEASUREMENTS AND RESULTS: The total time spent at the bedside in the first 6 h did not differ between group A and B (group A = 72.3 min [MD], 87.2 min [RT], and 178.8 min [N] vs 98.8 min [MD], 12.5 min [RT], and 197.6 min [N] for group B). In the following 42 h, a plateau was reached so that there was a significant reduction for both groups in the time of assistance given by Ns (p<0.001) but not by MDs or RTs. The total costs were also not different between the two groups ($806+/-73 [US dollars per day] vs $864+/-44 for group A and B, respectively). In the subgroups monitored for the entire period of ventilation, a significant reduction in the time of assistance, for both MDs and Ns, was observed after approximately the first half. CONCLUSIONS: We conclude that in the first 48 h of ventilation, daily NIMV is neither more expensive nor time-consuming and staff demanding than InMV. After the first few days of ventilation, NIMV was significantly less time-consuming than InMV, for MDs and Ns, so that medical and paramedical time expenditure seems not to be a major problem during NIMV.

Acute Disease↗
PubMed1997

Portable power supply for continuous mechanical ventilation during intrahospital transport of critically ill patients with ARDS.

Patients with respiratory failure and poor pulmonary compliance requiring high levels of positive pressure ventilation are at high risk during intrahospital transportation. Most ICU ventilators currently do not have a built-in power supply. Manual bag-valve ventilation frequently is used but often without optimum mean airway pressures or minute ventilation guarantees. Transport ventilators also are limited in their ability to provide high positive end-expiratory pressure, variable inspiratory-expiratory ratios, or pressure-controlled ventilation. The 3M SARNS HELP (Hospital Emergency Limited Power) 115, a portable battery, provides continuous power to ICU ventilators and eliminates ventilator circuit interruption for the critical period of patient transportation.

Aged↗
PubMed1999

Four-year experience with a unit for long-term ventilation (respiratory special care unit) at the Cleveland Clinic Foundation.

BACKGROUND: In the context that special weaning units have been advocated as effective alternatives to the ICU for weaning selected patients, we initiated a Respiratory Special Care Unit (ReSCU) at the Cleveland Clinic Hospital in August 1993. The goals of the ReSCU were the following: (1) to wean ventilator-dependent patients when possible; and (2) when weaning was not possible, to optimize patient and family instruction for patients going home with ventilatory support. This study presents our 4-year experience with 212 patients managed in the ReSCU and analyzes clinical features associated with favorable clinical outcomes. METHODS: The features of the ReSCU include six private beds in a pulmonary inpatient ward staffed by nurses with special pulmonary expertise; 24-h respiratory therapy supervision; bedside and central noninvasive monitoring (i.e., continuous pulse oximetry, end tidal capnometry, and ventilator alarms); and a multidisciplinary approach involving dietitians, physical therapists, occupational therapists, social workers, and speech pathologists. All ReSCU patients were cared for primarily by a pulmonary/critical care attending physician and fellow, with consultative input solicited as deemed necessary. The criteria for admission to the ReSCU included hemodynamic stability; absence of an arrhythmia requiring telemetry; and in the attending physician's judgment, the ability to benefit from the ReSCU. RESULTS: Between August 23, 1993, and August 31, 1997, 212 patients were admitted to the ReSCU. The median age was 68 years old; 55% were women; 86% were white; and 55% were transferred from the medical ICU. Underlying reasons for ventilator dependence were ARDS from a nonsurgical cause (33%), ARDS following surgery (18%), status post-cardiothoracic surgery (13%), status post-thoracic surgery (12%), and COPD (12%). The median length of ReSCU stay was 17 days (interquartile range, 10 to 29 days). Eighteen percent (n = 38) died during the hospitalization. Among the 174 survivors, complete ventilator independence was achieved in 127 patients (60% of the 212 patient cohort), 28 patients were ventilator dependent (13% of 212 patients), and the remaining 19 patients (9%) required partial ventilatory support. Univariate analysis regarding the association of baseline characteristics with death identified lower albumin and transferrin levels, increasing age, and the physician's estimate of lower weaning likelihood as significant correlates of death. In contrast, achieving complete ventilator independence was associated with a higher serum albumin level, a nonmedical ICU referral source, a cause of respiratory failure other than COPD, and a physician's estimate of higher weaning likelihood. To analyze the financial impact of the ReSCU, we assumed that ReSCU patients would have otherwise stayed in the medical ICU and compared the charges (ICU vs ReSCU) with, for a subset of patients, the true costs of ReSCU vs. ICU care. Analyses of both charges and cost differences showed similar savings associated with ReSCU care ($13,339 per patient [charges] and $10,694 per patient [costs]). CONCLUSIONS: We conclude the following: (1) the rate of achieving complete ventilator independence in the ReSCU was high; and (2) based on our achieving clinical outcomes, which are comparable to the most favorable rates reported in other series from ventilator units, we conclude that the ReSCU can be an effective and cost-saving alternative to the ICU for carefully selected patients.

Aged↗
PubMed1999

Lack of influence of gender on outcomes of mechanically ventilated medical ICU patients.

STUDY OBJECTIVES: Recent studies combining medical and surgical patients have suggested that mortality is higher for mechanically ventilated women than for men. This study was designed to determine whether there are gender-based differences in outcomes in mechanically ventilated medical ICU (MICU) patients. DESIGN AND SETTING: Prospective observational study in an MICU of a tertiary-care academic medical center. PATIENTS: Five hundred eighty consecutive patients admitted to the MICU service and mechanically ventilated for a minimum of 12 h. RESULTS: There was no difference in overall hospital mortality rate (woman, 36.3%; men, 40.4%; p > 0.2). No differences in mortality rates were noted after stratification based on age, underlying comorbid condition, APACHE (acute physiology and chronic health evaluation) II score, indication for mechanical ventilation, or acute hepatic or renal failure. Using a multiple logistic regression model, gender was not independently associated with hospital mortality. No differences were found between men and women for a number of secondary outcomes, including likelihood of undergoing weaning trials, success of weaning trials, time between onset of mechanical ventilation and extubation, total time on mechanical ventilation, rate of unplanned extubations, need for reintubation or tracheostomy, or duration of MICU and hospital stay, after the onset of mechanical ventilation. The number and timing of orders written to withhold care were comparable between men and women. CONCLUSIONS: Using univariate and multivariate analyses, we found no differences in hospital mortality rates between mechanically ventilated men and women. Differences in the process of care or gender-based treatment bias may explain previously reported differences in outcomes.

APACHE↗
PubMed1986

Monaghan 225 ventilator use under hyperbaric conditions.

The Monaghan 225 ventilator was tested to ambient pressures of 6 atmospheres absolute (ATA) in a hyperbaric chamber. The ventilator would function with delivered tidal volume which was independent of ambient pressure. Ventilatory rate declined in an exponential fashion. At 6 ATA, the ventilatory rate was 45 percent of the preset rate at 1 ATA. By decreasing the circuit resistance and increasing the inspiratory flow rate, the 6 ATA rate could be increased to 72 percent of the 1 ATA value. The maximum minute ventilation of the ventilator at 1 ATA was approximately 48 L/min; at 6 ATA, its maximum was 18 L/min. Synchronized intermittent mandatory ventilation, assist/control, and PEEP functions were satisfactory at 6 ATA. While using 100 percent O2 to power the ventilator at 2.82 ATA, the oxygen leakage was 57.7 L/min (converted to 1 ATA pressure, 20 degrees C), of which 33.7 L/min was successfully scavenged using simple techniques. A minor modification was made to the ventilator, allowing it to be driven by compressed air while maintaining complete flexibility in setting the FIo2. The ventilator has proven stable and reliable in clinical use at ambient pressures up to 6 ATA.

Equipment Design↗
PubMed2004

Pressure support versus assisted controlled noninvasive ventilation in neuromuscular disease.

INTRODUCTION: Noninvasive ventilation (NIV) is being increasingly used in patients with chronic neuromuscular disorders, but the optimal ventilation mode remains unknown. We compared physiological short-term effects of assist/controlled ventilation (ACV) and two pressure-limited modes (pressure-support ventilation [PSV] and assist pressure-controlled ventilation [ACPV]) in patients with neuromuscular disease who needed NIV. METHODS: Tidal volume was 10 to 12 mL/kg. The ACPV mode used the same respiratory cycle timing as the volume-limited mode. The level of inspiratory support was set to achieve the same tidal volume during the other ventilatory modes. RESULTS: Thirteen patients with neuromuscular disease who met international criteria for NIV were included. The three ventilatory modes increased alveolar ventilation and decreased respiratory effort indices. However, no difference in breathing or respiratory effort was found among the three modes, with the exception that inspiratory peak flow and percentage of triggered cycles were higher during PSV than volume-limited ventilation. Interestingly, no relationship was observed between subjective patient preference and inspiratory effort indices or percentage of triggered cycles. CONCLUSION: In chronic, stable patients with neuromuscular disease, both noninvasive ACV, ACPV, and PSV had similar effects on alveolar ventilation and respiratory muscle unloading, despite some differences in the pattern of breathing and percentage of triggered cycles.

Adult↗
PubMed1999

Randomized placebo-controlled trial of a 42-Day tapering course of dexamethasone to reduce the duration of ventilator dependency in very low birth weight infants.

OBJECTIVE: To assess the effect on duration of ventilator dependency of a 42-day tapering course of dexamethasone in very low birth weight neonates. METHODS: Infants (N = 118) were assigned randomly, within birth weight/gender strata, to treatment with either a 42-day tapering course of dexamethasone or an equal volume of saline as placebo. Entry criteria were 1) birth weight <1501 g; 2) age between 15 and 25 days; 3) <10% decrease in ventilator settings for 24 hours and FIO2 >/=0.3; 4) absence of patent ductus arteriosus, sepsis, major congenital malformation, congenital heart disease; and 5) no evidence of maternal HIV or hepatitis B infection. The dosage schedule was 0.25 mg/kg bid for 3 days, then 0.15 mg/kg bid for 3 days, then a 10% reduction in the dose every 3 days until a dose of 0.1 mg/kg had been given for 3 days, from which time a dose of 0.1 mg/kg qod was continued until 42 days after entry. The primary endpoint was the number of days on assisted ventilation after study entry. Secondary outcomes of interest included days on supplemental oxygen, days of hospitalization, and potential adverse effects, such as infection, gastrointestinal bleeding, left ventricular hypertrophy, and severe retinopathy of prematurity. RESULTS: Infants in the dexamethasone- and placebo-treated groups were similar in terms of baseline attributes, including birth weight, gestational age, gender, race, and ventilator settings at entry. Infants treated with dexamethasone were on assisted ventilation and supplemental oxygen for fewer days after study entry (median days on ventilator, 5th and 95th percentiles, 13 [1-64] vs 25 [6-104]; days on oxygen, 59 [6-247] vs 100 [11-346]). No differences were found in risk of death, infection, or severe retinopathy. In subgroup analyses, the association of dexamethasone with more rapid weaning from the ventilator was weaker among infants enrolled before the 16th day of life, infants with chest radiographs showing cystic changes and/or hyperinflation, and infants requiring an FIO2 >/=0.7 or a peak inspiratory pressure >/=19 at study entry. CONCLUSIONS: A 42-day tapering course of dexamethasone decreases the duration of ventilator and oxygen dependency in very low birth weight infants and is not associated with an increased risk of short-term adverse effects.

Confounding Factors, Epidemiologic↗
PubMed1991

Effect of PEEP-valve placement on function of a home-care ventilator.

BACKGROUND: The addition of a PEEP valve to the circuit of a home-care ventilator like the Aequitron LP-6 can be viewed as a consumer modification of the system. We sought to determine the effect that such a modification would have on ventilator function. METHODS & MATERIALS: Part 1. We tested the effect of PEEP level and PEEP-valve position on volume delivered at the ventilator Y-adapter, over a range of tidal volumes. Part 2. We held tidal volume, frequency, and inspiratory time constant, and varied PEEP level and PEEP-valve position to test the effect of PEEP-valve position on pressures measured at the ventilator outlet, patient-Y, and within the exhalation-valve pressurization line. RESULTS: Conventional placement of the PEEP value (distal to, or 'after,' the exhalation valve) in the LP-6 ventilator circuit resulted in statistically significant and potentially clinically important decreases in the volumes delivered to the patient at some ventilator settings. Proximal placement of the PEEP valve (proximal to, or 'before,' the exhalation valve) resulted in consistent volumes delivered to the patient at all levels tested, without changing the ventilatory performance characteristics of the ventilator as reflected by pressure waveforms. CONCLUSION: We recommend that appropriate observations and measurements be made to verify system function before a home-care ventilator modified to provide PEEP is applied to the patient.

Evaluation Studies as Topic↗
PubMed1991

Compression volume in adult ventilator circuits: a comparison of five disposable circuits and a nondisposable circuit.

UNLABELLED: Although the concept of ventilator circuit compression is well known, it is not fully appreciated clinically. We compared the compression volume of five adult disposable ventilator circuits and a nondisposable circuit. METHODS: Five brands of disposable circuits (Inspiron, Intertech, Marquest, Seamless, and U-Mid) and one nondisposable brand (Bennett) were used. The circuits were attached to the outlet of a Bennett MA-1 ventilator in the standard manner, and the filter and humidifier were bypassed to eliminate their contribution to compression volume. The ventilator delivered 1 L of gas to a Michigan Instruments Test Training Lung at a flow of 60 L/min and a rate of 12/min. A valve system was placed between the Y-connector and the TTL to partition circuit compression volume from the volume delivered to the test lung. The compression factor was calculated by dividing the compression volume by the ventilating pressure. Five compliance settings were used on the TTL (0.1, 0.05, 0.03, 0.02, and 0.015 L/cm) to simulate different ventilating pressures. Pressure at the Y-connector, compressible volume, and volume delivered to the TTL were measured using a calibrated Timeter RT200 volume-pressure analyzer. Five measurements were made with each brand. A new circuit was used for each run with a disposable circuit, and a different circuit from the respiratory care department stock was used for each run with a nondisposable circuit. RESULTS: There were significant differences between the compression factors at different TTL compliance settings (p less than 0.001), and brands of circuits evaluated (p less than 0.001). There was a significant interaction effect for compression factors between TTL compliance setting and circuit brands (p less than 0.001). The compression factors for all disposable circuits were greater than the compression factors for the nondisposable circuits (p less than 0.05). CONCLUSIONS: There were differences in circuit compression factors as a function of the ventilating pressure and the brand of circuit. Although these differences are too small to be clinically important in many cases, they may be important during ventilation with low tidal volumes and high pressures.

Adult↗
PubMed1992

Variations in tidal volume with portable transport ventilators.

BACKGROUND: As intra- and interhospital transportation of ventilator-dependent patients has become more commonplace, the number of portable transport ventilators has increased. Transport ventilators should be capable of delivering consistent tidal volume (VT) from breath to breath following changes in lung-thorax compliance and airways resistance. We sought to determine the effect of changes in compliance (C) and resistance (R) on the VT delivered by eight commercially available, time-cycled transport ventilators. METHODS & MATERIALS: Each ventilator (PneuPAC Model 2, Autovent 3000, MAX, Bird Transport Mini-TXP, IC-2A, P7, E100i, and Logic 07a) was connected to a calibrated pneumotachograph and a test lung set for normal adult C (C = 100 mL/cm H2O [1.02 L/kPa]) and R (R = 2 cm H2O.s.L-1 [0.2 kPa.s.L-1]), with VT at 1,000 mL. RESULTS: As C and R were manipulated, VT varied widely. Tidal volume decreased least with the P7 and most with the Bird transport ventilator. CONCLUSION: Decreases in VT with a transport ventilator predispose patients to hypoventilation, hypercapnia, and acidemia. Tidal volume often is not monitored continuously during transport, yet large decreases in VT must not be allowed when pulmonary mechanics are unstable. Internal pressure-limiting valves, venturi flow-generating devices, and compression volume in the breathing circuit are at least three factors that affect VT with transport ventilators.

Equipment Design↗
PubMed1994

Treatment of acute respiratory failure with non-invasive intermittent positive pressure ventilation in haematological patients.

OBJECTIVE: The aim of this study was to assess whether non-invasive positive pressure ventilation delivered intermittently (Ni-IPPV) by means of a facial or nasal mask is beneficial in haematological patients suffering from acute respiratory failure. DESIGN: Prospective, open, non-randomised study. SETTING: University Hospital, medical intensive care unit. PATIENTS AND METHOD: Eighteen haematological patients with acute respiratory failure which occurred before, during or just after therapeutic aplasia were ventilated with Ni-IPPV delivered via an individual nasal mask or a standard facial mask. Non-invasive ventilation was achieved until weaning (success (S)) or intubation (failure (F)). RESULTS: Twelve patients were ultimately intubated and died (F group). Seven needed intubation within 3 hours following admission because of the inability of Ni-IPPV to provide adequate ventilation in six patients and after cardiac arrest, probably related to cardiac aspergillosis in one patient. Six patients were not intubated and were discharged alive (S group). Of 11 patients who received Ni-IPPV for more than 3 hours, the respiratory rate decreased significantly (p < 0.05) from 33 +/- 7 breaths/min to 24 +/- 5 breaths/min with Ni-IPPV and the PaO2 increased significantly from 6.6 +/- 1.7 kPa upon admission to 17.7 +/- 5.5 kPa during Ni-IPPV. Mean daily ventilation was 12 +/- 7 hours for a mean duration of 5.5 +/- 4.4 days. Pressure support was used in nine patients and appeared the most efficient ventilation mode of non-invasive ventilation. The duration per day of Ni-IPPV was shorter and PaCO2 values during Ni-IPPV were lower in the S group than in the F group. CONCLUSIONS: This technique is able to provide adequate ventilatory support for many haematological patients and allows avoidance of ventilation in some.

Acute Disease↗
PubMedDate not supplied

Determination of ventilatory minute volumes for normocapnic ventilation under anaesthesia in healthy adults.

BACKGROUND: Mechanical ventilation under anaesthesia needs to be controlled to maintain normal oxygen and carbon dioxide tensions in the blood and to economize on fresh gas flows. Various ventilation nomograms such as Radford's nomogram and Nunn's CO2 predictor are based on data from studies, some of which do not mimic the conditions which prevail under anaesthesia. We, therefore, planned a study to formulate nomograms for normocapnic ventilation for anaesthetized adult subjects. METHODS: Two hundred and fifty-three patients with normal pulmonary function tests, scheduled for elective non-thoracic surgery were studied. Subjects were ventilated with a Siemens Servo 900 B ventilator using CO2 analyser 930 (Siemens-Elema Sweden) to adjust the minute volume sufficient to maintain end-tidal carbon dioxide fraction (FE,CO2) at around 5.5 normocapnia (PaCO2 5.06-5.6 kPa). This was confirmed with arterial blood gas analysis. RESULTS: The mean (SD) ventilation required for male patients was 6.123 (0.91) L [105 (13.1) ml/kg]. This was significantly higher than the requirement for female patients [5.262 (0.82) L; 98.7 (13.3) ml/kg]. The minute volume requirements showed a significant correlation with weight (W), height (H), body surface area, body mass index and other combinations of weight and height such as W x H, W/H, W2, W3 and H/W1/3. Nomograms were constructed for different weights and heights of males and females using multiple regression analysis. These minute volumes were found to be significantly higher than those calculated according to Radford's nomogram as well as Nunn's CO2 predictor and significantly lower than the Adelaide ventilation guide. CONCLUSION: The differences obtained in our nomograms are probably because the earlier ones were based on minute carbon dioxide production and physiological dead space data obtained from widely differing studies, some of which did not resemble conditions prevailing under anaesthesia. None of these used strict inclusion criteria such as pulmonary function tests. These may also be due to a difference in body structure between the subjects studied. Therefore, minute volume requirements calculated based on available western nomograms should not be applied to Indian subjects for normocapnic ventilation under anaesthesia.

Adolescent↗
PubMed1999

[From tracheostomy to non-invasive mask ventilation: a study in children with congenital central hypoventilation syndrome].

BACKGROUND: Children with congenital central hypoventilation syndrome (CCHS) have to be ventilated during sleep due to respiratory insensitivity to CO2. This long-term mechanical ventilation sometimes requires a tracheostomy during infancy, leading to increased risk of infections and of tracheal problems, and later on to stigmatization and restrictions in social life. PATIENTS AND METHOD: We therefore evaluated non-invasive mask ventilation in 4 children between 6 and 15 years of age, who had been ventilated via tracheal canula since early infancy under polysomnographic control. RESULTS: Best results were obtained with standard face masks in connection with pressure controlled timed ventilation. In 1 child we used a volume-controlled ventilator. The lack of dyspnea in these patients can worsen the acceptance of a face mask, which is more uncomfortable than a tracheal cannula. In 2 children we waited with the definite closure of the tracheostomy due to pavor-like symptoms and laryngeal closure during sleep and problems in acceptance of the mask, respectively. In the other 2 children we could demonstrate effective non-invasive mask ventilation during temporary tracheal closure for several nights. Therefore the tracheostomy was definitely closed. Long-term follow-up with home monitoring showed effectiveness of non-invasive ventilation in these cases.

Adolescent↗