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PubMed1992

[A comparative study of the cost of open-circuit as opposed to closed-circuit ventilation].

The authors compared two open randomized groups of patients undergoing surgery through general anaesthesia. Group 1 consisted of 54 patients ventilated by a Siemens 900 B ventilator in open circuit, and group 2, 56 patients ventilated by an ELSA de Gambro ventilator in a closed circuit. Comparative hour cost for nitrous oxide (N2O), oxygen (O2) and halogen gas, Enflurane, Isoflurane, was noted. All patients received the same regimen of anaesthesia and the two groups were identical in age, weight, surgery, respiratory volume and ventilation time. The evaluation of comparative hour cost included specific materials of close circuit ventilator: CO2 filter (Aridus), Lime. Were excluded maintenance and gas consumption expenditures before patient connected to the ventilator. The total hour cost (O2, N2O, specific materials for close circuit, without halogen gas) was 8.23 FF in closed circuit against 13.28 FF in open circuit, an economy of 38.27%. Hence, for oxygen, the hour cost was 0.70 FF in open circuit against 0.27 FF in closed circuit (gain of 65.3%). For nitrous oxide, the hour cost in open circuit was 12.50 FF against 2.44 FF in closed circuit (80.5%). For Isoflurane, the open circuit hour cost was 41.38 FF against 22.44 FF in closed circuit (47%). For Enflurane, the open circuit hour cost was 14.17 FF against 5.94 FF in closed circuit (58.1%). And, lastly for Enflurane, open circuit hour cost was 14.17 FF against 5.94 FF in close circuit, gain of 58.1%. These "modest" economy against those found in previous studies can be explained by the long-time duration of ventilation, saturating time in open circuit more or less long, depending on the physician, specific materials for closed circuit ventilation--lime, CO2 filter--in not taken into account, the hour cost of O2 + NO2 goes from 8.23 FF to 2.71 FF, and the gain against the close circuit becomes 79.6%: reducing hour cost by 5 times. In order to improve the effective cost of close circuit, the authors proposed: the use of closed circuit ventilation for more than 3 hours surgery, gas saturation in closed circuit after denitrogenation--which demands the use of halogen infjectors, and lime in containers cheaper than disposable cartridges. Respecting the above criteria, the total hour cost in close circuit fell to 4.90 FF, gain of 63% against open circuit. For O2 et N2O, the hour cost goes from 1.34 FF in close circuit to 13.28 FF in open circuit, 90% economy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Ventilator use by muscular dystrophy association patients.

Two hundred seventy-three Muscular Dystrophy Association (MDA) clinic directors and codirectors of 167 of the 220 clinics responded to a survey designed to study patterns of use of mechanical ventilation. Ventilatory assistance was recommended and used on an elective basis in 43 of the 167 clinics. In 68 clinics, the policy was to discourage its use, and 62 clinics were managing no ventilator users at the time of the survey. The most common reason given for discouraging ventilator use was poor patient quality of life. Only two physicians who discouraged use of mechanical ventilation were familiar with newly described methods of noninvasive ventilatory aid. The clinic directors were also asked to estimate the satisfaction with life of Duchenne muscular dystrophy (DMD) ventilator users. Eighty DMD ventilator users also responded to a separate and identical life satisfaction survey. The clinic directors significantly underestimated the users' reported life satisfaction. The directors who discouraged ventilator use more significantly underestimated the users' life satisfaction than those who recommended it. We conclude that the MDA clinic directors' estimation of ventilator users' quality of life and satisfaction with life is positively correlated with the likelihood of their discussing and recommending ventilator use to prolong life. Despite the wider recognition and availability of more convenient noninvasive methods of ventilatory assistance, the use of mechanical ventilation by MDA clinics has not changed significantly since 1985.

Adult↗

PubMed2005

Peak pressures during manual ventilation.

INTRODUCTION: Manual (bag) ventilation sometimes achieves better oxygenation than does a mechanical ventilator. We speculated that clinicians might generate very high airway pressure during manual ventilation (much higher than the pressure delivered by a mechanical ventilator), and that the high airway pressure causes alveolar recruitment and thus improves oxygenation. Such high pressure might injure alveoli in some patients. METHODS: We tested the hypothesis that manual ventilation may involve substantially higher pressure than is delivered by a mechanical ventilator. We asked experienced respiratory therapists to manually ventilate a lung model that was set to represent several typical clinical scenarios. RESULTS: We found that the peak airway pressure generated by the therapists was sometimes in excess of 100 cm H(2)O. CONCLUSIONS: The high airway pressure during manual ventilation would be considered extreme in the context of conventional mechanical ventilation, which raises questions about whether manual ventilation causes barotrauma.

Airway Resistance↗

PubMed2005

A laboratory evaluation of 2 mechanical ventilators in the presence of helium-oxygen mixtures.

BACKGROUND: Helium-oxygen (heliox) mixtures are being used more frequently with mechanical ventilators. Newer ventilators continue to be developed that have not yet been evaluated for safety and efficacy of heliox delivery. We studied the performance of 2 previously untested ventilators (Servo-i and Inspiration) during heliox administration. METHODS: We measured tidal volume (V(T)) delivery, gas blending, gas analyzing, and pressure stability in the presence of heliox. A heliox (80% helium/20% oxygen) tank was attached to the 50-psi air inlet. We compared the set V(T) (ie, set on the ventilator) and the exhaled V(T) (measured by the ventilator) to the delivered V(T) (measured with a lung model). Pressure measurements were also evaluated. We also compared the ventilator-setting fraction of inspired oxygen (F(IO(2))) to the F(IO(2)) measured by the ventilator and the F(IO(2)) measured with a supplemental oxygen analyzer. RESULTS: Heliox significantly affected both the exhaled V(T) measurement and the actual delivered V(T) (p < 0.001) with both the Servo-i and the Inspiration. Neither peak inspiratory pressure (in the pressure-controlled ventilation mode) nor positive end-expiratory pressure were adversely affected by heliox with either ventilator. Introducing heliox into the gas-blending systems caused only a small error in F(IO2) delivery and monitoring. CONCLUSIONS: Both Ventilators cycled consistently with heliox mixtures. In most cases, actual delivered V(T) can be reliably calculated if the F(IO2) and the set V(T) or the measured exhaled V(T) is known. With the Servo-i, at high helium concentrations the exhaled V(T) measurement was unreliable and caused a high-priority alarm condition that couldn't be disabled. A supplemental oxygen analyzer is not necessary with either device for heliox applications.

Administration, Inhalation↗

PubMed2006

[Actualities of adults' ventilator-associated pneumonia].

Pneumonia is the most frequently reported nosocomial infection in intensive care unit patients, predominantly in mechanically ventilated individuals. Most of the studies performed in intensive care unit settings reported the estimated 15-65% of ventilator-associated pneumonia, with high mortality rates. Ventilator-associated pneumonia results in prolonged hospitalization and increase in medical care costs. In most cases, high-risk pathogens (e.g. Gram-negative bacteria, such as Pseudomonas aeruginosa, Acinetobacter spp. and Klebsiella spp. with wide spectrum resistance, as well as methicillin-resistant Staphylococcus aureus) are the predominant causative agents of increased mortality. Occurrence of ventilator-associated pneumonia correlates with the duration of mechanical ventilation, severity of illness on admission (predicted mortality), type of admission (medical, surgical, trauma), demographical factors and treatment. Effective antibiotic management programs provide the information on local patterns of antimicrobial resistance, therefore, the proper antibiotic therapy can be chosen empirically. Invasive management strategy reduces mortality, earlier prevents organ dysfunction and lower antibiotic consumption in patients with suspected ventilator-associated pneumonia. The major goal of ventilator-associated pneumonia management is to optimize antimicrobial therapy by administering correct antibiotics in adequate doses and avoiding the initial use of wide spectrum antimicrobials. The antibiotic therapy should depend on antimicrobial sensitivity testing results and the clinical patient's response. The duration of therapy should be shortened to the minimum effective period. Excessive antibiotic use is a major factor contributing to increased antibiotic-resistance of pathogens. Prevention of the ventilator-associated pneumonia by local multidisciplinary strategies may reduce mortality rates and is beneficiary both for the patients and the hospital system. The education of the nursing staff helps to decrease the occurrence of ventilator-associated pneumonia in intensive care unit setting. However, ventilator-associated pneumonia still remains a serious controversy-generating problem in intensive care unit.

Adult↗

PubMed1979

Collateral ventilation.

Ventilation may bypass obstructed airways through collateral channels, including interalveolar pores of Kohn, bronchiole-alveolar communications of Lambert, and interbronchiolar pathways of Martin. Resistance through these channels, like resistance through small airways, increases with decreasing lung volume and with hypocapnia. But whereas the distention of collateral channels and small airways by a variety of factors is similar, the efficiency of ventilation through collateral channels is less than the efficiency through airways. Gas inspired through collateral channels is contaminated with alveolar gas from surrounding lung so that the dead space for collateral ventilation is increased. When one part of the lung ventilates out of phase with the surrounding lung, pulmonary interdependence promotes more homogeneous ventilation. In the presence of airways obstruction, interdependence may be a primary factor governing the rate of collateral ventilation. In man, collateral ventilation is unimportant in normal lungs. However, with disease, it may be critical in producing or compensating for abnormalities. For example, the long time constant for collateral ventilation in the middle lobe may be responsible for atelectasis, which results in the middle lobe syndrome. On the other hand, the short time constant for collateral ventilation in emphysema may be essential for the distribution of ventilation beyond obstructed airways.

Airway Resistance↗

PubMed1996

Pressure support ventilation.

The field of ventilatory support has changed dramatically with the introduction of improvements in technology and new ventilatory modes. The most recent ventilators are characterized by microprocessor technology, making the interaction between patient and ventilator more sophisticated than ever before. This technology has enabled the development of pressure support ventilation, which has gained extensive popularity during the past 10 years. Pressure support ventilation is different from controlled mechanical ventilation or intermittent mandatory ventilation; pressure support ventilation is characterized by a unique combination of simultaneous spontaneous and mechanical breathing, so that the ventilatory and flow rates and tidal volume depend on the patient's breathing pattern and the set level of pressure support. Pressure support ventilation can be used as a stand-alone ventilatory support mode and alternative to volume-controlled ventilation, and it can be used in weaning patients from mechanical ventilation.

Humans↗

PubMed1996

High-frequency jet ventilation in the early management of respiratory distress syndrome is associated with a greater risk for adverse outcomes.

OBJECTIVE: The objective of this investigation was to determine if high-frequency jet ventilation (HFJV) used early in the treatment of premature infants with respiratory distress syndrome was effective in reducing pulmonary morbidity without increasing the occurrence of adverse neurologic outcomes. STUDY DESIGN: A total of 73 premature infants who met the inclusion criteria (gestational age of less than 33 weeks, birth weight of more than 500 g, age of less than 24 hours, need for assisted ventilation with peak inspiratory pressure of more than 16 and FIO2 more than 0.30, and roentgenographic evidence of respiratory distress syndrome) were randomized to either conventional (n = 36) or to high-frequency jet (n = 37) ventilation. Our goals were to maintain the infants on the assigned ventilator for at least 7 days unless they could either be extubated or meet crossover criteria. Univariate analyses were initially used to compare the two groups. Stepwise logistic regression was subsequently used to assess whether various factors independently influenced adverse outcomes. RESULTS: The two groups of infants were similar in all obstetrical, perinatal, and neonatal demographic characteristics. The mean birth weight and gestational age in the conventional group were 930 g and 26.6 weeks and in the HFJV group, 961 g and 26.9 weeks. The infants were randomized at similar ages (7.1 and 7.3 hours of life, respectively). Their prerandomization ventilator settings and arterial blood gases were nearly identical. There were no differences in pulmonary outcomes (occurrence of air leaks, need for oxygen or ventilation at 36 weeks postconception), and there were no differences in the mean number of days oxygen was required, number of days ventilated, or length of hospital stay. Infants ventilated with HFJV were significantly more likely to develop cystic periventricular leukomalacia (10 vs 2, P = .022) or to have a poor outcome (grade IV hemorrhage, cystic periventricular leukomalacia, or death) (17 vs 7, P = .016). Logistic regression analysis revealed HFJV to be a significant independent predictor of both cystic periventricular leukomalacia and a poor outcome. The presence of hypocarbia was not an independently significant predictor of adverse outcomes. CONCLUSIONS: With the HFJV treatment strategy that we used, use of the high-frequency jet ventilator in the early management of premature infants with respiratory distress syndrome resulted in significantly more adverse outcomes than in those treated with conventional mechanical ventilation.

Blood Pressure↗

PubMed1996

Noninvasive ventilation for postoperative support and facilitation of weaning.

Noninvasive ventilation includes continuous positive airway pressure with mask, positive pressure ventilation with mask, and negative pressure body ventilation. Noninvasive ventilation is a ventilatory support mode intermediate in both effectiveness and potential complications between oxygen administration and intubation with mechanical ventilation. The advantages, disadvantages, and experimental results of the use of noninvasive ventilation in patients who have been extubated following recovery from surgery and subsequently experience respiratory difficulties are discussed. In general, noninvasive ventilation seems to provide useful ventilatory support in about three of four patients in whom it is tried. In addition, the use of noninvasive ventilation as an aid to weaning of patients from mechanical ventilation is discussed. This use of noninvasive ventilation has not yet been extensively reported, although it appears to be potentially useful.

Acute Disease↗

PubMed1997

Ventilator-CPAP with the Siemens Servo 900C compared with continuous flow-CPAP in intubated patients: effect on work of breathing.

The effects of continuous positive airway pressure (CPAP) provided by the Siemens Servo 900C ventilator were compared with a continuous flow system (CF-CPAP) in patients weaning from the ventilator. Thirteen patients were studied using both systems at a CPAP level of 0.5 kPa. Additional work of breathing (Wapp) and derived variables were determined in relation to the minute volumes of the patients. The Wapp imposed by the ventilator exceeded the Wapp of CF-CPAP in all patients. The difference in Wapp between ventilator- and CF-CPAP was greater at higher ventilatory needs. The increments in Wapp imposed by the ventilator were positively correlated with the actual end-expiratory pressures (EEP). The EEP increasingly exceeded the preset CPAP level of the ventilator at higher minute volumes. An inspiratory threshold due to a gradient between EEP and preset CPAP greatly increased the Wapp imposed by the ventilator. As this threshold was attributed to the resistance of the PEEP device of the ventilator, it indicates that the additional work related to the expiratory value should be taken into account when the Siemens Servo 900C ventilator is used for weaning purposes.

Adult↗

PubMed2000

Effect of perfluorochemical liquid ventilation on cardiac output and blood pressure variability in neonatal piglets with respiratory insufficiency.

Respiration and mechanical ventilation induce cyclic variation in cardiac output and blood pressure. We examined these phasic hemodynamic influences of mechanical ventilation during gas ventilation and partial and tidal liquid ventilation in 7 anesthetized and paralyzed young piglets (body weight, 3.0-4.9 kg) made respiratory-insufficient by repeated saline lung lavage. Nonlinear regression analysis of cardiovascular parameters vs. time was done to quantify respiratory-induced fluctuations in hemodynamic variables. The amplitude of oscillations was expressed as a percentage of the mean hemodynamic variable during the study period, and was called the relative oscillation amplitude. The relative oscillation amplitude of left ventricular stroke volume, left ventricular output, systemic arterial pressure, and systemic perfusion pressure was significantly larger (at least twofold) during tidal liquid ventilation compared to partial liquid ventilation. No such differences were observed between gas and partial liquid ventilation at comparable gas ventilator settings. We conclude that in this animal model, within-breath modulation of left ventricular output, systemic blood pressure, and perfusion pressure was significantly increased during tidal liquid ventilation as compared to partial liquid ventilation.

Animals↗

PubMed1998

Gas leak and gastric insufflation during controlled ventilation: face mask versus laryngeal mask airway.

PURPOSE: To compare two airway management techniques, face mask (FM) with oropharyngeal airway and laryngeal mask airway (LMA), with respect to the effectiveness of positive pressure ventilation and airway maintenance. METHODS: After induction of anaesthesia, two airway management techniques (FM or LMA) and three peak pressures (20, 25 and 30 cm H2O) were randomly applied during controlled ventilation in 60 patients. Data collected included inspiratory and expiratory volumes and presence of gastro-oesophageal insufflation. Leak was calculated by subtracting the expiratory from the inspiratory volume, expressed as a fraction of the inspiratory volume. RESULTS: Expiratory volumes (mean +/- SD) at 20, 25 and 30 cm H2O for LMA ventilation were 893 +/- 260, 986 +/- 276 and 1006 +/- 262 respectively, and for FM ventilation 964 +/- 264, 1100 +/- 268 and 1116 +/- 261. Leak fractions at 20, 25 and 30 cm H2O for LMA ventilation were 0.21 +/- 0.15, 0.24 +/- 0.18 and 0.26 +/- 0.18 respectively, and for FM ventilation 0.14 +/- 0.09, 0.14 +/- 0.09 and 0.12 +/- 0.08. The frequency of gastro-oesophageal insufflation was 1.6%, 5% and 5% for the LMA and 5%, 15% and 26.6% for the FM for ventilation pressures of 20, 25 and 30 cm H2O respectively which was greater with LMA use. CONCLUSION: Ventilation was adequate in all patients using both techniques. Leak was pressure dependent and greater with LMA use. Most of the leak was vented to the atmosphere via the pharynx. Gastro-oesophageal insufflation was more frequent with ventilation using the face mask. LMA use with positive pressure ventilation would appear to be a better airway management method than the face mask.

Adult↗

PubMed1999

[Quality of emergency ventilation. A prospective study of trauma patients].

INTRODUCTION: The prehospitaly initiated endotracheal intubation and controlled ventilation, is especially in multi-system-trauma cases, recognized to be the "gold standard". Thus especially in view of the increasing demands being placed upon the quality of prehospital emergency treatment in general, the quality of such prehospital induced ventilation, is becoming of increasing importance. Thereby we must take into consideration the limited possabilities, which are afflicted with a high degree of uncertainess, which we have at our disposal to effectively evaluate the efficiency of emergency ventilation. The purpose of our study within a collective of severely traumatized patients, was to determine the quality of prehospitaly induced ventilation with regards to the adequacy of oxygenation and ventilation and as a result of our findings, to identify areas for procedural optimization. RESULTS: The prospective study over an one year period involved n = 104 trauma cases (male: 79; female: 25/age: 39.8 +/- 20.8 years/ISS: 28.1 +/- 15.3) whose prehospital emergency treatment required and included endotracheal intubation and controlled ventilation. All patients were subject to a prehospital pulse oxymetric monitoring, whereas none were subject to an objectivating apparatus monitoring of ventilation: 94.2% of the patients were upon admission adequately oxygenated (paO2 > 80 mmHg); only one patient was hypoxemic (paO2 < 60 mmHg). 46.2% were adequately ventilated (paCO2: 35-45 mmHg), 43.2% however were hyperventilated (paCO2 < 35 mmHg), and 10.6% hypoventilated (paCO2 > 45 mmHg). A statistical significant relation between hyper-/hypoventilation and the degree of severity of trauma as well as to the individual injury pattern was not evident. However with reference to age: The group of > 60 years of age were significantly more frequently hyperventilated (paCO2 < 30 mmHg: 31.2%; p < 0.05). A noteworthy accumulation of hypoventilation was experienced amongst the group of patients, who during the prehospital treatment phase were hemodynamic instable (shock index > 1). CONCLUSION: In summary it is evident, that as a rule, even very severe traumatized patients can prehospitaly be adequately oxygenated and that such oxygenation can with the assistance of pulse oxymetric monitoring be effectively controlled. Remaining problem is the emergency physicians ability to evaluate and control ventilation. The prehospital determination of minute volume (MV) in accordance with the presently valid recommendation: MV = 100-150 ml/kg body weight, in the majority of trauma cases results in inadequate ventilation. The introduction of an objectifying monitoring method is therefore urgently required.

Adolescent↗

PubMed2004

Incidence, risk factors and outcome of barotrauma in mechanically ventilated patients.

OBJECTIVE: To determine the incidence, risk factors, and outcome of barotrauma in a cohort of mechanically ventilated patients where limited tidal volumes and airway pressures were used. DESIGN AND SETTING: Prospective cohort of 361 intensive care units from 20 countries. PATIENTS AND PARTICIPANTS: A total of 5183 patients mechanically ventilated for more than 12 h. MEASUREMENTS AND RESULTS: Baseline demographic data, primary indication for mechanical ventilation, daily ventilator settings, multiple-organ failure over the course of mechanical ventilation and outcome were collected. Barotrauma was present in 154 patients (2.9%). The incidence varied according to the reason for mechanical ventilation: 2.9% of patients with chronic obstructive pulmonary disease; 6.3% of patients with asthma; 10.0% of patients with chronic interstitial lung disease (ILD); 6.5% of patients with acute respiratory distress syndrome (ARDS); and 4.2% of patients with pneumonia. Patients with and without barotrauma did not differ in any ventilator parameter. Logistic regression analysis identified as factors independently associated with barotrauma: asthma [RR 2.58 (1.05-6.50)], ILD [RR 4.23 (95%CI 1.78-10.03)]; ARDS as primary reason for mechanical ventilation [RR 2.70 (95%CI 1.55-4.70)]; and ARDS as a complication during the course of mechanical ventilation [RR 2.53 (95%CI 1.40-4.57)]. Case-control analysis showed increased mortality in patients with barotrauma (51.4 vs 39.2%; p=0.04) and prolonged ICU stay. CONCLUSIONS: In a cohort of patients in whom airway pressures and tidal volume are limited, barotrauma is more likely in patients ventilated due to underlying lung disease (acute or chronic). Barotrauma was also associated with a significant increase in the ICU length of stay and mortality.

Adult↗

PubMed2005

Noninvasive positive pressure ventilation in infants with upper airway obstruction: comparison of continuous and bilevel positive pressure.

OBJECTIVE: This study evaluated the efficacy of noninvasive continuous positive pressure (CPAP) ventilation in infants with severe upper airway obstruction and compared CPAP to bilevel positive airway pressure (BIPAP) ventilation. DESIGN AND SETTING: Prospective, randomized, controlled study in the pulmonary pediatric department of a university hospital. PATIENTS: Ten infants (median age 9.5 months, range 3-18) with laryngomalacia (n=5), tracheomalacia (n=3), tracheal hypoplasia (n=1), and Pierre Robin syndrome (n=1). INTERVENTIONS: Breathing pattern and respiratory effort were measured by esophageal and transdiaphragmatic pressure monitoring during spontaneous breathing, with or without CPAP and BIPAP ventilation. MEASUREMENTS AND RESULTS: Median respiratory rate decreased from 45 breaths/min (range 24-84) during spontaneous breathing to 29 (range 18-60) during CPAP ventilation. All indices of respiratory effort decreased significantly during CPAP ventilation compared to unassisted spontaneous breathing (median, range): esophageal pressure swing from 28 to 10 cmH(2)O (13-76 to 7-28), esophageal pressure time product from 695 to 143 cmH(2)O/s per minute (264-1417 to 98-469), diaphragmatic pressure time product from 845 to 195 cmH(2)O/s per minute (264-1417 to 159-1183) During BIPAP ventilation a similar decrease in respiratory effort was observed but with patient-ventilator asynchrony in all patients. CONCLUSIONS: This short-term study shows that noninvasive CPAP and BIPAP ventilation are associated with a significant and comparable decrease in respiratory effort in infants with upper airway obstruction. However, BIPAP ventilation was associated with patient-ventilator asynchrony.

Airway Obstruction↗

PubMed1988

Phrenic nerve and vagal nerve activities during differential lung ventilation in cats.

The effect of differential lung ventilation (DLV) on afferent vagal and efferent phrenic nerve activities was studied in urethane anesthetized cats. One endotracheal tube was inserted into the left bronchus to ventilate its side lung. Another tube was inserted until its tip reached about 1 cm above the carina to ventilate the right lung. Using two respirators, each lung was ventilated independently. Using hooked silver electrodes, the vagal and phrenic nerve activities were recorded. The afferent vagal nerve was activated in concurrence with lung inflation at any ventilation rate. The right and left vagal nerves were activated by right and left lung ventilation, respectively. On the other hand, the right and left efferent phrenic nerves were synchronized, whether the ventilation was discussed or ventilation was achieved by right or left one lung ventilation or even by asynchronous DLV. The phrenic nerve activity was surpressed by one-lung, right or left, ventilation independently, so that the rhythm of the phrenic nerve was disturbed by asynchronous DLV. From these results, to reduce the stress of patients during asychronous DLV, it was considered that patients need heavier sedation than a usual mechanical ventilatory support.

Journal Article↗

PubMed1993

Cadaver lung donors: effect of preharvest ventilation on graft function.

The pulmonary donor pool would increase substantially if lungs could be safely transplanted after cessation of circulation. To determine whether ventilation of cadaver lungs could improve graft function, canine donors were sacrificed and then ventilated with 100% oxygen (n = 6) or 100% nitrogen (n = 6); 6 served as nonventilated controls. Four hours after death, the lungs were flushed with modified Euro-Collins solution and harvested. Controls were ventilated with 100% oxygen only during flush and harvest. Recipients were rendered dependent on the transplanted lung by occlusion of the right pulmonary artery and bronchus 1 hour after transplantation. Ventilation was maintained at a constant inspired oxygen fraction of 0.4. Four controls died of pulmonary edema shortly after occlusion of the native lung. The mean arterial oxygen tensions in the oxygen-ventilated, nitrogen-ventilated, and control groups at the end of 8 hours were 81 mm Hg (n = 4), 88 mm Hg (n = 3), and 55 mm Hg (n = 2), respectively. Postmortem oxygen ventilation improved early recipient survival and gas exchange. Postmortem nitrogen ventilation improved early gas exchange and delayed recipient death compared with non-ventilated controls. The mechanics of ventilation appears to confer a functional advantage independent of a continued supply of oxygen. Transplantation of lungs harvested from cadavers after cessation of circulation might be feasible.

Animals↗

PubMed1994

Risks and hazards of mechanical ventilation: a collective review of published literature.

A collective, analytic review was undertaken of all available published scientific papers that reported data about risks, hazards, adverse effects, or complications from augmentation of blood gas exchange by means of intensive closed system positive pressure mechanical ventilation. On the basis of the data collected, the adverse effects of intensive positive pressure mechanical ventilation were classified into the following groups: oxygen toxicity; adverse effects from excessive ventilatory pressures, volumes, and flow rates; adverse effects from tracheal intubation; dangers from adjuvant drugs; stress-related sequelae; altered enzyme and hormone systems; nutritional problems; and psychologic trauma. A bibliography pertaining to each group of adverse effects has been prepared. In addition, the reported incidence of adverse effects resulting from intensive mechanical ventilation in patients in clinical intensive care is shown. Clinical and laboratory observations of patients who receive intensive positive pressure mechanical ventilation in respiratory intensive care units have yielded some data, and findings from experimental studies in normal volunteers and laboratory animals have also been collected and reviewed. Tables, charts, and graphs that summarize the pertinent findings are presented and discussed. The following conclusions are drawn from critical evaluation of the collected data: (1) Closed system positive pressure mechanical ventilation applied at mild to moderate levels of intensity is a safe and effective method for augmenting deficient blood gas exchange in most patients who are in acute respiratory failure. (2) On the other hand, intensive levels of mechanical ventilator support or inappropriate methods of applying mechanical ventilation may be accompanied by a variety of risks, hazards, adverse effects, and complications that may further injure the failing lungs or may add significantly to the morbidity and mortality rates of patients in whom it is applied. (3) Because of the unfavorable risk/benefit ratio of intensive positive pressure mechanical ventilation, physicians should consider the use of alternative methods that are now available for augmenting blood gas exchange in patients in acute respiratory failure who are not adequately treated by safe (mild to moderate) levels of positive pressure mechanical ventilation instead of electing to increase the intensity of positive pressure mechanical ventilation to more dangerous (intensive) levels.

Animals↗