Neonatal volume guarantee ventilation: effects of spontaneous breathing, triggered and untriggered inflations

BACKGROUND

During volume guarantee (VG) ventilation the peak inflating pressure (PIP) for each ventilator inflation is adjusted to ensure the expired tidal volume (V(Te)) is close to the set V(Te). Differences in the PIP between inflations triggered by the infant's inspirations and untriggered inflations are seen.

AIM

To investigate the effects of triggered and untriggered inflations on PIP and V(Te).

METHODS

Neonates were ventilated with the Dräger Babylog 8000 using assist control (synchronous intermittent positive pressure ventilation) and VG modes. Continuous recordings of ventilator pressures and tidal volumes were made at 200 Hz for 10 minutes.

RESULTS

In 10 infants, 6540 inflations were analysed, of which 4052 (62%) were triggered. Triggered inflations had a significantly lower mean (SD) PIP than untriggered inflations: 12.9 (4.9) vs 17.0 (3.3) cm H2O, (p<0.001). Despite this, there was no significant difference in the V(Te) of each type of inflation (103% and 101% of the set V(Te), respectively). When a triggered inflation was immediately preceded or followed by an untriggered inflation the PIP changed by about 5 cm H2O. Between adjacent inflations of the same type, the change in PIP was less than 3 cm H2O: for triggered inflations it was 0.11 (1.50) cm H2O and for untriggered inflations 0.06 (1.53) cm H2O.

CONCLUSION

During VG ventilation with the Dräger Babylog 8000 the PIP was 4 cm H2O lower during triggered inflations than untriggered inflations, although the expired tidal volumes were similar.

Postoperative use of nasal intermittent positive pressure in a patient with spinal muscular atrophy type II

We report the successful use of nasal intermittent positive pressure ventilation (NIPPV) in the perioperative period of a 51 yr-old woman with a type II spinal muscular atrophy (SMA II). The patient was treated chronically with nocturnal NIPPV at home and scheduled for endoscopic retrograde cholangiopancreatography (ERCP) under general anesthesia. Some criteria of difficult intubation were present (forced mouth opening of 1.5 cm, short neck and thyromental distance of 5 cm). Nasal endotracheal fiberoptic intubation during spontaneous breathing under sedation with propofol was performed. The ERCP procedure was conducted without complications. At the end of the procedure, IPPV was maintained until recovery of respiratory function. After extubation, NIPPV was continued in the recovery room. The patient was discharged from the post-anesthesia care unit 4 hours after the procedure. Management of patients with SMA remains a challenge and clinicians must be aware that the use of NIPPV may be a useful and life-saving tool in the perioperative period for these patients.

Noninvasive positive-pressure ventilation in acute respiratory failure

Noninvasive positive-pressure ventilation is a type of mechanical ventilation that does not require an artificial airway. Studies published in the 1990s that evaluated the efficacy of this technique for the treatment of diseases as chronic obstructive pulmonary disease, congestive heart failure and acute respiratory failure have generalized its use in recent years. Important issues include the selection of the ventilation interface and the type of ventilator. Currently available interfaces include nasal, oronasal and facial masks, mouthpieces and helmets. Comparisons of the available interfaces have not shown one to be clearly superior. Both critical care ventilators and portable ventilators can be used for noninvasive positive-pressure ventilation; however, the choice of ventilator type depends on the patient's condition and therapeutic requirements and on the expertise of the attending staff and the location of care. The best results (decreased need for intubation and decreased mortality) have been reported among patients with exacerbations of chronic obstructive pulmonary disease and cardiogenic pulmonary edema.

A randomized controlled trial of synchronized nasal intermittent positive pressure ventilation in RDS

OBJECTIVE

Comparison of outcomes of infants with respiratory distress syndrome (RDS), post-surfactant, extubated to synchronized nasal intermittent positive pressure ventilation (SNIPPV) or continued on conventional ventilation (CV).

STUDY DESIGN

Prospective post-surfactant randomized controlled trial of primary mode SNIPPV compared with CV in infants (born from July 2000 to March 2005) with birth weights (BW) of 600 to 1250 g. Primary mode SNIPPV was defined as its use in the acute phase of RDS, following the administration of the first dose of surfactant.

RESULT

There were no significant differences in the maternal demographics, antenatal steroid use, mode of delivery, BW, gestational age, gender or Apgar at 5 min between infants continued on CV (n=21) and those extubated to primary mode SNIPPV (n=20). Significantly, more babies in the CV group had the primary outcome of bronchopulmonary dysplasia (BPD)/death, compared to the SNIPPV group (52 versus 20%, P=0.03). There was no difference in the incidence of other common neonatal morbidities. There were no differences in the Mental or Psychomotor Developmental Index scores on follow-up between the two groups.

CONCLUSION

Infants of BW 600 to 1250 g with RDS receiving surfactant with early extubation to SNIPPV had a significantly lower incidence of BPD/death. Primary mode SNIPPV is a feasible method of ventilation in small premature infants.

Neonatal nasal intermittent positive pressure ventilation: what do we know in 2007?

Although neonatal nasal intermittent positive pressure ventilation (NIPPV) is widely used today, its place in neonatal respiratory support is yet to be fully defined. Current evidence indicates that NIPPV after extubation of very premature infants reduces the rate of reintubation. However, much is still not known about NIPPV including its mechanisms of action. It may improve pulmonary mechanisms, tidal volume and minute ventilation but more studies are required to confirm these findings. There is some evidence that NIPPV marginally improves gas exchange. More research is needed to establish which device is best, what settings to use or whether to use synchronised rather than non-synchronised NIPPV, and about the way to wean NIPPV. Future studies should enrol sufficient infants to detect uncommon serious complications and include long-term follow up to determine important neurodevelopment and pulmonary outcomes.

[18 years experience with mechanical ventilation in patients with Duchenne muscular dystrophy]

OBJECTIVE

To find out which patients with Duchenne muscular dystrophy are eligible for starting home mechanical ventilation and what the survival rate is.

DESIGN

Retrospective.

METHOD

In 48 patients with Duchenne muscular dystrophy who were treated with home ventilation from 1987, the results were assessed in the follow-up visit in February 2005. Initially, ventilation was only given through a tracheotomy (TPPV), but after starting up a multidisciplinary neuromuscular consultation, non-invasive ventilation (NIPPV) was offered in an earlier stage of the disease. The following data were derived from the outpatient medical record: indication for ventilation, vital capacity (VC), arterial blood gas values, duration of ventilation up to February 2005, survival and causes of death.

RESULTS

15 patients died. The 5-year survival rate was 75% from the start of mechanical ventilation and 67% (18/27) of the patients were still living at home at the time of the follow-up visit. The most important causes of death were cardiomyopathy (5/15) and tracheal bleeding (3/15). The group of patients who started ventilation before 1995 (n = 17) had a significantly smaller VC than the group (n = 31) who started after the neuromuscular consultation was set up. The PaCO2 during daytime was significantly higher in the group that started ventilation before 1995 compared to the group that started later.

CONCLUSION

Home mechanical ventilation can be implemented effectively in patients with Duchenne dystrophy, with a 5-year survival of 75%.

Atelectatic children treated with intrapulmonary percussive ventilation via a face mask: clinical trial and literature overview

BACKGROUND

Persistent atelectasis in children is lacking a gold standard treatment. Intrapulmonary percussive ventilation (IPV) is presented as a promising chest physiotherapy technique in the treatment of atelectasis. This study aimed to follow the evolution of atelectasis resolution with noninvasive IPV in young children and to detect eventual adverse effects.

METHODS

Six children were hospitalized for respiratory distress with suspicion of atelectasis. A 15 min IPV treatment was immediately started at D1 twice a day for 5 days. Children were free of any other treatment. Chest X-Ray (CXR) was performed on the second day (D2) and was repeated 3 days later (D5). After the study, CXR were retrospectively reviewed by three specialists who had no knowledge of the clinical observations of the patients. They were asked to assess atelectasis by a score between 4 (complete collapse) and 0 (complete resolution). A clinical score on a maximum of 4 points was assessed by appetite deterioration, dyspnoea, mucus production and cough presence at D1 and D5 (1 point per symptom present). Paired t-test compared D1 and D5 results.

RESULTS

All patients returned home after 5 days IPV. SpO2 normalized (93.2 +/- 0.8 to 95.3 +/- 0.8; P = 0.002) and patients all improved clinically (score, 2.8 +/- 0.9 to 0.8 +/- 0.6; P < 0.05). Out of four patients with radiographic evidence of atelectasis, three improved their atelectasis score.

CONCLUSIONS

No side-effect or adverse effect was observed during IPV treatments. IPV was safe and effective in atelectasis resolution in 3/4 of the cases. Patients all recovered a stable clinical state. CXR improved in 4/5 children. They were all discharged home after 5 days of IPV treatment.

Airway pressure release and biphasic intermittent positive airway pressure ventilation: are they ready for prime time?

Airway pressure release ventilation and biphasic positive airway pressure ventilation are being used increasingly as alternative strategies to conventional assist control ventilation for patients with acute respiratory distress syndrome (ARDS) and acute lung injury. By permitting spontaneous breathing throughout the ventilatory cycle, these modes offer several advantages over conventional strategies to improve the pathophysiology in these patients, including gas exchange, cardiovascular function, and reducing or eliminating the need for heavy sedation and paralysis. Whether these surrogate outcomes will translate into better patient outcomes remains to be determined. The purpose of this review is to summarize the rationale behind the use of these ventilatory strategies in ARDS, the clinical experience with the use of these modes, and their future applications in trauma patients.

The Amyotrophic Lateral Sclerosis Functional Rating Scale Predicts Survival Time in Amyotrophic Lateral Sclerosis Patients on Invasive Mechanical Ventilation

OBJECTIVE

To determine whether the amyotrophic lateral sclerosis functional rating scale (ALSFRS), which is a validated instrument that assesses the functional status and the disease progression in patients with amyotrophic lateral sclerosis (ALS), predicts hospital length of stay and survival time in ALS patients treated with tracheostomy-intermittent positive-pressure ventilation (TIPPV).

METHODS

Thirty-three consecutive ALS patients with acute respiratory failure who received therapy with TIPPV were prospectively followed up from their admission to the hospital until death. The association of ALSFRS score at hospital admission with length of hospital stay and survival after TIPPV were examined using Cox proportional hazard models, adjusting for age at baseline, sex, and symptom duration.

RESULTS

The median ALSFRS score of the ALS patients at hospital admission was 11 (range, 4 to 22). The median length of hospital stay was 55 days (range, 7 to 124 days), with a hospital mortality rate of 9%. For the 30 patients (91%) discharged from the hospital, the median survival time was 37 months (range, 2 to 64 months). The total ALSFRS score (above or below the median score) was a significant predictor of length of hospital stay (hazard ratio [HR], 2.86; 95% confidence interval [CI], 1.2 to 6.5; p = 0.003) and survival after TIPPV (HR, 3.76; 95% CI, 1.4 to 9.7; p = 0.002). The total ALSFRS score at hospital admission was also associated with length of hospital stay (HR, 2.1; 95% CI, 1.1 to 5.1; p = 0.005) and survival (HR, 0.52; 95% CI, 0.1 to 0.8; p = 0.002) when included in a Cox multivariable model together with the other demographic and clinical variables.

CONCLUSION

In ALS patients with acute respiratory failure who have been treated with TIPPV, the total ALSFRS score may predict length of hospital stay and long-term survival after invasive mechanical ventilation.

Aniline-induced methaemoglobinaemia in a glucose-6-phosphate dehydrogenase enzyme deficient patient

A case of methaemoglobinaemia following ingestion of an aniline-containing material is described. The detrimental effect of methylene blue, the classical antidote of methaemoglobinaemia, in a patient with glucose-6-phosphate dehydrogenase deficiency is highlighted.

Laparoscopic Nissen fundoplication during gastrostomy tube placement and noninvasive ventilation may improve survival in type I and severe type II spinal muscular atrophy

Progressive respiratory muscle weakness with bulbar involvement is the main cause of morbidity and mortality in type I and severe type II spinal muscular atrophy. Noninvasive positive pressure ventilation techniques coupled with laparoscopic gastrointestinal procedures may allow for improved morbidity and mortality. The authors present a series of 7 spinal muscular atrophy patients (6 type I and 1 severe type II) who successfully underwent laparoscopic gastrostomy tube insertion coupled with Nissen fundoplication and early postoperative extubation using noninvasive positive pressure ventilation techniques. The authors measured the length of survival and the frequencies of pneumonia and hospitalization before and after surgery as outcomes of these new surgical and medical interventions. All 7 patients had respiratory symptoms (unmanageable oropharyngeal secretions, cough, pneumonia), difficulty feeding, and weight loss. Six patients had documented reflux via diagnostic testing preoperatively. Five patients were on noninvasive positive pressure ventilation and other supportive respiratory therapies prior to surgery. All 7 patients survived the procedures. By August 2006, 5 patients with type I and 1 with severe type II spinal muscular atrophy were alive and medically stable at home 1.5 months to 41 months post-op. One patient with type I expired approximately 5 months post-op due to obstructive apnea. This case series demonstrates that laparoscopic gastrostomy tube placement coupled with Nissen fundoplication and noninvasive positive pressure ventilation can be successfully used as a treatment option to allow for early postoperative extubation and to optimize quality of life in type I and severe type II spinal muscular atrophy patients.

Spinal anaesthesia and non-invasive positive pressure ventilation for hip surgery in an obese patient with advanced chronic obstructive pulmonary disease

We describe the use of non-invasive positive pressure ventilation combined with spinal anaesthesia to allow the insertion of a dynamic hip screw in an obese patient with advanced chronic obstructive pulmonary disease. The technique avoided the hazards of intubation and general anaesthesia in this high-risk patient.

Tracheoscopy assisted repair of tracheo-esophageal fistula (TARTEF): a 10-year experience

BACKGROUND

Fiberoptic tracheoscopy assisted repair of tracheoesophageal fistula (TARTEF) has been reported to be useful for the surgeon with regards to identification of the fistula and proper fistula ligation. The aim of this article is to report our 10-year experience using TARTEF with intermittent positive pressure ventilation (IPPV) during tracheoesophageal fistula (TEF) repair in newborns.

METHODS

With ethical committee approval, we included all patients undergoing TARTEF from 1995-2005. Variables of interest were (1) respiratory deterioration caused by gastric inflation because of IPPV during surgery and endoscopy; (2) detection of additional airway anomalies; (3) success of intubation of the fistula; (4) other side effects or adverse events. Data are given in median and range.

RESULTS

Forty-seven neonates with TARTEF were included. Mean gestational age was 37 weeks (31-42) and mean weight was 2.5 kg (1.1-3.8). The patients were intubated with tracheal tubes size 2.5-3.5 mm ID. Appropriately sized fiberoptic bronchoscopes with an outer diameter of 2.0, 2.4 and 2.8 mm were used; passed through the lumen of the tracheal tube (TT) thereby requiring the use of IPPV to ensure adequate ventilation. No respiratory deterioration was noted as a consequence of intraoperative fiberoptic manipulation within the trachea or because of gastric hyperinflation with IPPV. In all patients, the TEF was successfully penetrated with the fiberscope and this clearly helped the surgeon to rapidly identify and dissect the fistula. In two patients a tracheal bronchus was identified. In two patients accidental extubation occurred during endoscopic confirmation of successful fistula repair.

CONCLUSIONS

While fiberoptic TARTEF through the tracheal tube with IPPV did expedite and facilitate surgery, it did not cause clinically relevant impairment of ventilation. Careful manipulation during fiberoptic assessment is required to avoid tube displacement.

Respiratory patterns during sleep in obesity-hypoventilation patients treated with nocturnal pressure support: a preliminary report

BACKGROUND

The obesity-hypoventilation syndrome (OHS), commonly defined as a combination of obesity and diurnal hypercapnia, is efficiently treated using nasal positive pressure ventilation (NPPV). The present study aimed to determine whether nocturnal polysomnography allows detection of respiratory disturbances occurring in patients with OHS treated with NPPV that may interfere with the quality of sleep and of ventilatory support, and are not detected by nocturnal pulse oximetry and capnography.

METHODS

Twenty OHS patients in stable clinical condition treated by NPPV for at least 3 months with a bilevel pressure support ventilator were studied. All patients underwent single-night polysomnography under NPPV including transcutaneous measurement of Pco(2) (TcPco(2)). Four types of respiratory events were defined and quantified: patient/ventilator desynchronization, periodic breathing (PB), autotriggering, and apnea-hypopneas.

RESULTS

Eleven patients (55%) exhibited desynchronization occurring mostly in slow-wave sleep and rapid eye movement sleep and associated with arousals but not inducing significant changes in TcPco(2) or oxygen saturation using pulse oximetry (Spo(2)). Eight patients (40%) showed a high index of PB, mostly occurring in light sleep and associated with more severe nocturnal hypoxemia. Autotriggering was sporadic and usually limited to one or two breaths, although prolonged and asymptomatic autotriggering occurred in one patient during 10.6% of total sleep time.

CONCLUSIONS

Patient/ventilatory asynchrony and PB are respiratory patterns occurring frequently in OHS patients treated using NPPV. Nocturnal monitoring of Spo(2) and TcPco(2), commonly used to assess the efficacy of ventilatory support, do not adequately explore this aspect of therapy that might influence its efficacy as well as sleep quality.

The effects of adaptive servo ventilation on cerebral vascular reactivity in patients with congestive heart failure and sleep-disordered breathing

STUDY OBJECTIVE

Hypercapnic cerebral vascular reactivity (HCVR) is reduced in patients with congestive heart failure (CHF) and sleep-disordered breathing (SDB); this may be associated with an increased risk of stroke. We tested the hypothesis that reversal of SDB in CHF patients using adaptive servo ventilation (ASV) would increase morning HCVR.

DESIGN

Interventional, cross-over clinical study.

SETTING

Research sleep laboratory.

PATIENTS

Ten CHF patients with SDB, predominantly obstructive sleep apnea.

INTERVENTIONS

The HCVR was measured from the change in middle cerebral artery velocity, using pulsed Doppler ultrasound. HCVR was determined during the evening (before) and morning (after) 1 night of sleep on ASV and 1 night of spontaneous sleep (control).

MEASUREMENTS AND RESULTS

Compared with the control situation, ASV decreased the apnea-hypopnea index (group mean +/- SEM, control: 48 +/- 12, ASV: 4 +/- 1 events per hour). HCVR was 23% lower in the morning, compared with the evening, on the control night (evening: 1.3 +/- 0.2, morning: 1.0 +/- 0.2 cm/sec per mm Hg, P < 0.05) and 27% lower following the ASV night (evening: 1.5 +/- 0.2, morning: 1.1 +/- 0.2 cm/sec per mm Hg, P < 0.05). The effect of ASV on the evening-to-morning reduction in HCVR was not significant, compared with the control night (0.02 cm/sec per mm Hg, 95% confidence interval: -0.28, 0.32 P = 0.89).

CONCLUSIONS

In CHF patients with SDB, HCVR was reduced in the morning compared with the evening. However, removal of SDB for 1 night did not reverse the reduced HCVR. The relatively low morning HCVR could be linked with an increased risk of stroke.

Full face mask for noninvasive positive-pressure ventilation in patients with acute respiratory failure

BACKGROUND

Noninvasive positive-pressure ventilation (NPPV) is commonly used to improve ventilation and oxygenation in patients with acute respiratory failure (ARF). Mask leak and intolerance due to facial discomfort or claustrophobia often occur with NPPV and are frequently cited reasons for treatment failure.

METHODS

Retrospective review of patient records from a tertiary-care referral hospital.

RESULTS

We report the effectiveness of a full face mask in the application of NPPV for 10 nonambulatory patients (mean [SD], 61 [9] years) who had a combined total of 13 episodes of ARF. After these patients were unable to receive NPPV therapy via the more commonly available nasal or oronasal masks, care was provided using full face masks. Eight of 10 patients had hypercapnic respiratory failure; 2 patients, hypoxemic respiratory failure. All patients were placed on ventilation initially using a bi-level positive airway pressure device. Subsequently, patient ventilation was achieved using a Puritan Bennett 7200a ventilator for on-line respiratory monitoring. The mean (SD) duration of treatment with NPPV was 9.7 (2.7) hours per day for 3.0 (1.6) days. Following NPPV via full face mask, the patients' Paco(2) decreased (65 [20] vs 82 [27] mm Hg, P=.09) and pH increased significantly (7.36 [0.07] vs 7.26 [0.07], P<.05) in less than 2 hours. Moreover, the patients demonstrated decreased respiratory rate (18 [7] vs 32 [8] breaths/min, P<.01), heart rate (106 [13] vs 124 [16] beats/min, P=.008), and Acute Physiology and Chronic Health Evaluation II scores (12 [3] vs 17 [4], P<.005) after NPPV via full face mask. These cardiorespiratory alterations occurred as early as 1 hour after NPPV initiation and were maintained throughout treatment. Two patients required endotracheal intubation because of copious purulent secretions.

CONCLUSION

For individuals with hypercapnic respiratory failure who cannot tolerate NPPV using nasal or oronasal masks, use of full face masks may improve outcomes, allowing physicians to avoid ordering endotracheal intubation and mechanical ventilation.

Neuromotor outcome at 2 years of very preterm infants who were treated with high-frequency oscillatory ventilation or conventional ventilation for neonatal respiratory distress syndrome

OBJECTIVE

In a previous multicenter, randomized trial, elective use of high-frequency oscillatory ventilation was compared with the use of conventional ventilation in the management of respiratory distress syndrome in preterm infants <30 weeks. No difference in terms of respiratory outcome was observed, but concerns were raised about an increased rate of severe intraventricular hemorrhage in the high-frequency ventilation group. To evaluate outcome, a follow-up study was conducted until a corrected age of 2 years. We report the results concerning neuromotor outcome.

METHODS

Outcome was able to be evaluated in 192 of the 212 infants who survived until discharge from the neonatal unit: 97 of 105 infants of the high-frequency group and 95 of 104 infants of the conventional ventilation group.

RESULTS

In the infants reviewed, mean birth weight and gestational age were similar in the 2 ventilation groups. As in the overall study population, the following differences were observed between the high-frequency ventilation group and the conventional ventilation group: lower 5-minute Apgar score, fewer surfactant instillations, and a higher incidence of severe intraventricular hemorrhage. At a corrected age of 2 years, 93 of the 97 infants of the high-frequency group and 79 of the 95 infants of the conventional ventilation group did not present any neuromotor disability, whereas 4 infants of the high-frequency group and 16 infants of the conventional ventilation group had cerebral palsy.

CONCLUSIONS

Contrary to our initial concern about the increased rate of severe intraventricular hemorrhage in the high-frequency ventilation group, these data suggest that early use of high-frequency ventilation, compared with conventional ventilation, may be associated with a better neuromotor outcome. Because of the small number of patients studied and the absence of any explanation for this finding, we can conclude only that high-frequency oscillatory ventilation is not associated with a poorer neuromotor outcome.

Tracheal sealing by auto-inflation in tracheal tube cuffs

BACKGROUND

The purpose of this study was to determine if inspiratory pressure from intermittent positive pressure ventilation may be sufficient to inflate the cuff (thus 'auto-inflation') and thereby seal the trachea.

METHODS

In a laboratory model we investigated the ability of cuffs of seven 5.0 mm internal diameter (ID) tracheal tubes (Sheridan CF, Mallinckrodt Hi-Contour, Mallinckrodt Sealguard, Mallinckrodt Safety-Flex, Portex Soft Seal, Rueschelit Super-Safety Clear and Microcuff PET) to seal the trachea by auto-inflation, i.e. by using the inspiratory pressure to expand and keep open the cuff within the trachea. A mechanical lung connected to a model trachea made from clear, rigid polyvinylchloride (PVC) (12 mm ID) was used to simulate changes in inspiratory pressures. Respirator settings were: fresh gas flow (air) 6 lxmin(-1); positive end-expiratory pressure 5 cmH(2)O; respiratory rate 20 brxmin(-1); I : E ratio = 1 : 2; inspiratory pressure 5, 10, 15, 20, and 25 cmH(2)O. Percentage of expiratory to inspiratory tidal volume (E : I V(t) volume ratio) was calculated.

RESULTS

Using lubricated Mallinckrodt Seal Guard tube cuffs E : I V(t) volume ratio was almost 100% at a peak inspiratory pressure of 10 cmH(2)o whereas in tube cuffs particularly made of PVC an E : I ratio was achieved only at higher inspiratory pressures, if at all.

CONCLUSIONS

Auto-inflation in the Mallinckrodt Seal Guard with high volume-low pressure polyurethane cuff can produce adequate tracheal sealing in the model trachea used. The implication is that such auto-inflation should decrease the risk of tracheal injury from acute or persistent cuff hyperinflation.

Impact of volume guarantee ventilation on arterial carbon dioxide tension in newborn infants: a randomised controlled trial

OBJECTIVE

To compare the effects of the two modes of ventilation, synchronous intermittent positive pressure ventilation (SIPPV) and SIPPV with Volume Guarantee (VG), on arterial carbon dioxide tension (PaCO(2)) immediately after neonatal unit admission.

STUDY DESIGN

Randomised study of ventilation mode for premature inborn infants admitted to two tertiary neonatal units. After admission, infants were randomised to receive either SIPPV or VG using a Dräger Babylog 8000 plus ventilator. In the SIPPV group, peak airway pressure was set clinically. In the VG group, desired tidal volume was set at 4 ml/kg, with the ventilator adjusting peak inspiratory pressure to deliver this volume. The study was completed once the first arterial PaCO(2) was available, with the desirable range defined as 5-7 kPa.

RESULTS

PaCO(2) was significantly higher in the VG group (VG: 5.7 kPa, SIPPV: 4.9 kPa; p=0.03). The VG group had fewer out-of-range PaCO(2) values (VG: 42%, SIPPV: 57%) and fewer instances of hypocarbia <5 kPa (VG: 32%, SIPPV: 57%) but neither difference achieved statistical significance. Regression analysis showed PaCO(2) was negatively correlated with gestation (r=-0.41, p=0.01) and also with the mode of ventilation (r=0.32, p<0.05). In the VG group, all infants 23-25 weeks' gestation had out-of-range PaCO(2) values. VG significantly reduced the incidence of out-of-range PaCO(2) and hypocarbia in infants over 25 weeks' gestation (VG: 27%, SIPPV: 61%; p<0.05).

CONCLUSION

Using this strategy, VG appears feasible in the initial stabilisation of infants over 25 weeks' gestation, with a halving of the incidence of hypocarbia. In the small number of babies studied below this gestation, VG was not found to be effective.

[An auto control comparison of the use of ProSeal laryngeal mask airway and standard laryngeal mask airway for positive pressure ventilation]

OBJECTIVE

To compare the ProSeal laryngeal mask airway (PLMA) and the standard laryngeal mask airway (SLMA) for intermittent positive pressure ventilation (IPPV) in a randomized auto control design.

METHODS

Fifty adult patients with American Society of Anesthesiologists (ASA) physical status 1-2, scheduled for elective plastic surgery under general anesthesia were recruited. After the routine intravenous anesthesia induction, the PLMA and the SLMA were inserted randomly in sequence into each patient and inflated to an intracuff pressure of 60 cm H(2)O (1 cm H(2)O=0.098 kPa), airway seal pressure and lung ventilation satisfaction were evaluated, and fiberoptic (FOB) scores of the cuff anatomic position were measured. The mean expired volume and the mean peak inspiratory pressure of five continuous breaths were calculated after IPPV with 10 ml/kg tidal volume was performed.

RESULTS

Without cuff inflation, airway seal pressure was higher with the PLMA than with the SLMA (P<0.05), and adequate or acceptable lung ventilation was obtained in 46 (92%) patients with the PLMA, but only 22 (44%) patients with the SLMA. When the air volume required to obtain an intracuff pressure of 60 cm H(2)O, adequate lung ventilation was obtained in 50 patients with the PLMA, but only 28 patients with the SLMA, and the inflation volume and sequential airway seal pressure were higher with the PLMA than with the SLMA (both P<0.05), and the airway seal pressure with the PLMA was not less than with the SLMA in each patient. The ventilation volume was higher with the PLMA than with the SLMA, except in 2 patients. The FOB score of the cuff position was lower with the PLMA than with the SLMA (P<0.05). The mean expired tidal volume and the mean peak inspiratory pressure were not significantly different between 29 patients with the PLMA and 21 patients with the SLMA for airway maintenance during operation (both P>0.05).

CONCLUSION

Compared with SLMA, PLMA can achieve a higher airway seal pressure and potentially isolate the glottis and the upper esophagus, and is safer and more effective for positive pressure ventilation.

Decreased lung injury after surfactant in piglets treated with continuous positive airway pressure or synchronized intermittent mandatory ventilation

BACKGROUND

Treatment with surfactant (S) decreases lung injury in paralyzed, mechanically ventilated animals. The use of nasal continuous positive airway pressure (CPAP) as an alternative to mechanical ventilation may further improve acute pulmonary outcomes.

OBJECTIVES

To evaluate the effect of surfactant (+S, -S) and synchronized intermittent mandatory ventilation (SIMV) on lung morphology and inflammatory markers in 24 spontaneously breathing piglets treated with CPAP or SIMV after saline lavage-induced lung injury.

METHODS

After induction of lung injury, animals were randomized to CPAP-S, CPAP+S or SIMV+S and treated for 4 h. Physiologic parameters were continuously monitored. After treatment, animals were euthanized and lungs fixed. Bronchoalveolar lavage (BAL) samples were collected for neutrophil count and H(2)O(2).

RESULTS

No physiologic differences were noted. BAL fluid from CPAP-S animals contained more neutrophils and more neutrophil H(2)O(2) than fluid from the SIMV+S or CPAP+S groups (p < 0.05 or greater). Pathologic injury scores were higher in dependent lung regions from CPAP groups (p < 0.05). Injury pattern scores showed greater dependent alveolar inflammation in all (p < 0.02), with more dependent atelectasis in the CPAP groups (p < 0.01). Morphometrics showed less total open alveolar air space in nondependent regions of the SIMV+S group compared to CPAP groups (p < 0.001). Dependent regions showed less total open alveolar air space compared to nondependent regions in the CPAP groups (p < 0.001).

CONCLUSIONS

Animals treated with surfactant prior to CPAP or SIMV had less acute lung injury. SIMV+S animals had less open air space in nondependent regions. This suggests, during early ventilatory support, surfactant administration may modulate pulmonary inflammation. CPAP alone without surfactant may not provide optimal pulmonary protection. The addition of mechanical breaths may alter and add to injury.

Noninvasive ventilation in a child affected by achondroplasia respiratory difficulty syndrome

Achondroplasia can result in respiratory difficulty in early infancy, from anatomical abnormalities such as mid-facial hypoplasia and/or adenotonsillar hypertrophy, leading to obstructive apnea, or to pathophysiological changes occurring in nasopharyngeal or glossal muscle tone, related to neurological abnormalities (foramen magnum and/or hypoglossal canal problems, hydrocephalus), leading to central apnea. More often, the two respiratory components (central and obstructive) are both evident in mixed apnea. Polysomnographic recording should be used during preoperative and postoperative assessment of achondroplastic children and in the subsequent follow-up to assess the adequacy of continuing home respiratory support, including supplemental oxygen, bilevel positive airway pressure, or assisted ventilation.

Intrapulmonary percussive ventilation improves the outcome of patients with acute exacerbation of chronic obstructive pulmonary disease using a helmet

OBJECTIVE

To evaluate the effect of intrapulmonary percussive ventilation (IPV) by mouthpiece during noninvasive positive-pressure ventilation with helmet in patients with exacerbation of chronic obstructive pulmonary disease (COPD).

DESIGN

Randomized clinical trial.

SETTING

General intensive care unit, university hospital.

PATIENTS

Forty patients with exacerbation of COPD ventilated with noninvasive positive-pressure ventilation by helmet were randomized to two different mucus clearance strategies: IPV (IPV group) vs. respiratory physiotherapy (Phys group). As historical control group, 40 patients receiving noninvasive positive pressure and ventilated by face mask treated with respiratory physiotherapy were studied.

INTERVENTIONS

Two daily sessions of IPV (IPV group) or conventional respiratory physiotherapy (Phys group).

MEASUREMENTS AND MAIN RESULTS

Physiologic variables were measured at entry in the intensive care unit, before and after the first session of IPV, and at discharge from the intensive care unit. Outcome variables (need for intubation, ventilatory assistance, length of intensive care unit stay, and complications) were also measured. All physiologic variables improved after IPV. At discharge from the intensive care unit, Paco2 was lower in the IPV group compared with the Phys and control groups (mean +/- sd, 58 +/- 5.4 vs. 64 +/- 5.2 mm Hg, 67.4 +/- 4.2 mm Hg, p < .01). Pao2/Fio2 was higher in IPV (274 +/- 15) than the other groups (Phys, 218 +/- 34; control, 237 +/- 20; p < .01). In the IPV group, time of noninvasive ventilation (hrs) (median, 25th-75th percentile: 61, 60-71) and length of stay in the intensive care unit (days) (7, 6-8) were lower than other groups (Phys, 89, 82-96; control, 87, 75-91; p < .01; and Phys, 9, 8-9; control, 10, 9-11; p < .01).

CONCLUSIONS

IPV treatment was feasible for all patients. Noninvasive positive-pressure ventilation by helmet associated with IPV reduces the duration of ventilatory treatment and intensive care unit stay and improves gas exchange at discharge from intensive care unit in patients with severe exacerbation of COPD.

Use of controlled ventilation in a clinical setting

Mechanical ventilation has long been used to maintain ventilation in humans when the lungs are rendered incapable of oxygenation or when respiration is affected by central nervous system depression, but it has only recently been applied to similar cases in dogs and cats. Although manual ventilation is still the more common form of ventilation in dogs and cats, mechanical intermittent positive-pressure ventilation (IPPV) is a much more efficient and reliable means of maintaining the highest quality of respiratory assistance. With proper training, technicians can use IPPV to support compromised animals until they are capable of maintaining normal oxygen concentrations.

Laryngeal function and nasal ventilatory support in the neonatal period

Nasal application of positive airway pressure, either intermittently or continuously, is increasingly used in the neonatal period. An important difference however when using a nasal interface as opposed to an endotracheal tube for ventilatory support is the interposition of the larynx. Recent animal studies from our laboratory showed that nasal ventilatory support in the neonatal period can significantly impact laryngeal function. This includes active laryngeal closure against intermittent positive pressure ventilation, which can limit lung ventilation, and inhibition of non-nutritive swallowing, which may delay swallowing maturation. Those novel findings are highly relevant to neonatal respiratory care. Additional studies are underway to uncover both the mechanisms involved and consequences on lung ventilation and swallowing function.

[Effects of expiratory triggering sensitivity on patient-ventilator expiratory synchrony and work of breathing in patients with chronic obstructive pulmonary disease during pressure support ventilation]

OBJECTIVE

To study the effects of expiratory triggering sensitivity (ETS) on patient-ventilator expiratory synchrony and work of breathing in chronic obstructive pulmonary disease (COPD) patients during pressure support ventilation (PSV).

METHODS

A total of 31 COPD patients were ventilated in PSV mode, and measured by a pulmonary monitor. Meanwhile, the electromyogram of the diaphragm (EMG(diaph)) was obtained with electromyography. Five levels of ETS, 1%, 15%, 25%, 35%, and 50% of peak inspiratory flow (PIF), were studied in random order. Each ETS level lasted 30 minutes and all the data were recorded simultaneously for 3 minutes at the end of each period. The effects of ETS on patient-ventilator expiratory synchrony were analyzed by measuring the phase angle of expiration between the EMG(diaph) and the flow wave curve, and the effects of ETS on work of breathing by calculating total work of breathing (Wtot), work of inspiration by patients (Wi, P) and expiratory work of breathing (Wex).

RESULTS

Ten patients were excluded from the study. At the 25% PIF level of ETS, patient-ventilator expiratory synchrony was the best, theta = (8 +/- 3) degrees, 16 patients - 15 degrees < or = theta < or = 15 degrees, and the amount of Wtot, Wi, p, Wex was the smallest among all the 5 levels of ETS, which was (1.86 +/- 0.53) J/L, (0.54 +/- 0.13) J/L, and (0.16 +/- 0.08) J/L respectively. When the level of ETS decreased, the occurrence of delayed termination of inspiration and the amount of Wex increased. At the level of 1% PIF, 18 patients theta > 15 degrees, and Wex was (0.48 +/- 0.10) J/L; at this level of ETS, Wi, p also increased significantly to (0.65 +/- 0.16 ) J/L. But when the level of ETS increased, the occurrence of premature termination of inspiration and the amount of Wi, p increased: at 50% PIF level of ETS, theta < - 15 degrees and Wi, p was (1.33 +/- 0.14) J/L in 19 patients.

CONCLUSION

The proper adjustment of ETS during PSV improves patient-ventilator synchrony and decreases work of breathing in COPD patients.

Diurnal ventilation via mouthpiece: survival in end-stage Duchenne patients

The present study aimed to assess the impact of diurnal mouthpiece intermittent positive pressure ventilation (MIPPV) as the extension of the nasal intermittent positive pressure ventilation (NIPPV) in Duchenne muscular dystrophy (DMD). In total, 42 DMD patients aged 15-33 yrs, normocapnic at night with NIPPV and receiving MIPPV since end-diurnal hypercapnia, were studied. Transcutaneous CO2 tension (Pt,CO2) was prospectively monitored at the end of the day, before and after MIPPV initiation. Vital capacity (VC), breathing pattern and maximal inspiratory strength were measured. Patients were asked to score the presence (1 point) or absence (0 point) of seven respiratory-linked symptoms before and after MIPPV establishment. Survival rates reached 88, 77, 58 and 51% after 1, 3, 5 and 7 yrs, respectively. The mean survival rate was 31 yrs. VC stabilised during 5 yrs with MIPPV. Symptom scores significantly decreased and Pt,CO2 normalised during the day (8.17 +/- 2.22 to 5.78 +/- 0.73 kPa). No accident and minor side-effects were observed in this 184 cumulated patient-yrs study. In conclusion, daytime mouthpiece ventilation is safe, prolongs survival and stabilises vital capacity in Duchenne muscular dystrophy patients. It is recommended on the condition that patients are equipped with a self-supporting harness.

Non-invasive ventilation in acute cardiogenic pulmonary oedema

Non-invasive ventilation (NIV) is the delivery of assisted mechanical ventilation to the lungs, without the use of an invasive endotracheal airway. NIV has revolutionised the management of patients with various forms of respiratory failure. It has decreased the need for invasive mechanical ventilation and its attendant complications. Cardiogenic pulmonary oedema (CPO) is a common medical emergency, and NIV has been shown to improve both physiological and clinical outcomes. From the data presented herein, it is clear that there is sufficiently high level evidence to favour the use of continuous positive airway pressure (CPAP), and that the use of CPAP in patients with CPO decreases intubation rate and improves survival (number needed to treat seven and eight respectively). However, there is insufficient evidence to recommend the use of bilevel positive airway pressure (BiPAP), probably the exception being patients with hypercapnic CPO. More trials are required to conclusively define the role of BiPAP in CPO.

Home mechanical ventilatory support in patients with restrictive ventilatory disorders: A 48-year experience

We performed a retrospective analysis to the effects of negative pressure ventilation (NPV), tracheal intermittent positive pressure ventilation (TIPPV), and nasal intermittent positive pressure ventilation (NIPPV, volume or pressure-controlled ventilatory mode), in 114 patients with restrictive ventilatory disorders instituted in our hospital from 1956 until 2005. The patients were assigned on "ad hoc" basis to NPV, TIPPV, or NIPPV. All patients were subdivided in an idiopathic kyphoscoliosis group (IK, n=64), a post-poliomyelitis syndrome group (PP, n=30), or a miscellaneous group (M, n=20). The patients in the PP group had higher survival rates compared to the IK patients (P<0.05), while the M patients had the lowest survival rates (P<0.01). Both NPV (P<0.01) and TIPPV (P<0.05) lead to a decrease in PaCO2 after 9 months compared to baseline. This decrease in PaCO2 was still present after 5 years NPV (P<0.001) and TIPPV (P<0.05). NIPPV lead to an improvement in pulmonary function (P<0.05) and arterial blood gases (P<0.001) after 9 months compared to baseline. After 5 years NIPPV, the arterial blood gases were still significantly improved compared to baseline (P<0.01). Both volume-controlled and pressure-controlled ventilation improved pulmonary function and arterial blood gases.

CONCLUSION

Long-term home mechanical ventilatory support by both NPV and positive pressure ventilation is effective in patients with IK, PP syndrome, and a M group, even after a period of 5 years.

Alternatives to endotracheal intubation for patients with neuromuscular diseases

OBJECTIVE

To evaluate the usefulness of continuous noninvasive mechanical ventilation and mechanical coughing aids to avoid endotracheal intubation and tracheostomy during episodes of acute respiratory failure in patients with neuromuscular disease.

DESIGN

We conducted a prospective cohort study at the respiratory medicine ward of a university hospital to study the success rate of the use of continuous noninvasive mechanical ventilation and manually and mechanically (CoughAssist) assisted coughing to avert endotracheal intubation in 24 consecutive episodes of acute respiratory failure for 17 patients with neuromuscular disease. The noninvasive mechanical ventilation and coughing aids were used to reverse decreases in oxyhemoglobin saturation and relieve respiratory distress that occurred despite oxygen therapy and appropriate medication. Noninvasive mechanical ventilation was delivered by volume ventilators (Breas PV 501) alternating nasal/oronasal and oral interfaces.

RESULTS

Noninvasive management was successful in averting death and endotracheal intubation in 79.2% of the acute episodes. There were no significant differences in respiratory function between the successfully treated and unsuccessfully treated groups before the current episode. Bulbar dysfunction was the independent risk factor for failure of noninvasive treatment (P < 0.05; odds ratio, 35.99%; 95% confidence interval, 1.71-757.68).

CONCLUSIONS

Intubation can be avoided for some patients with neuromuscular disease in acute respiratory failure by some combination of noninvasive mechanical ventilation and mechanically assisted coughing. Severe bulbar involvement can limit the effectiveness of noninvasive management.

Physiologic evaluation of different levels of assistance during noninvasive ventilation delivered through a helmet

OBJECTIVE

To evaluate the effects of various levels of pressure support (PS) during noninvasive ventilation delivered through a helmet on breathing pattern, inspiratory effort, CO2 rebreathing, and comfort.

DESIGN

Physiologic study.

SETTING

University-affiliated hospital.

PATIENTS AND PARTICIPANTS

Eight healthy volunteers.

INTERVENTIONS

Volunteers received ventilation through a helmet with four different PS/positive end-expiratory pressure combinations (5/5 cm H2O, 10/5 cm H2O, 15/5 cm H2O, and 10/10 cm H2O) applied in random order.

MEASUREMENTS AND RESULTS

The ventilatory respiratory rate, esophageal respiratory rate (RRpes), airway pressure, esophageal pressure tracings, esophageal swing, and pressure-time product (PTP) [PTP per breath, PTP per minute, and PTP per liter] were evaluated. We also measured the partial pressure of inspired CO2 (Pi(CO2)) at the airway opening, mean partial pressure of expired CO2 (Pe(CO2)), CO2 production (V(CO2)), minute ventilation (V(E)) delivered to the helmet (V(E)h), and the true inspired V(E). By subtracting V(E) from V(E)h, we obtained the Ve washing the helmet (V(E)wh). A visual analog scale (from 0 to 10) was used to evaluate comfort. Compared to spontaneous breathing, different levels of PS progressively increased tidal volume (V(T)) and decreased RRpes, reducing inspiratory effort. The increased levels of assistance did not produce significant changes in Pi(CO2), end-tidal CO2, and V(CO2). Pe(CO2) had a slight decrease when increasing the level of PS from 5 to 10 cm H2O (p < 0.05). Despite the presence of constant values of Ve, the increase of PS produced an increase in V(E)wh, without significant differences comparing 10 cm H2O and 15 cm H2O of PS. The subjects had a slight but not significant increase in discomfort by augmenting the level of assistance. At the highest level of PS (15 cm H2O), the discomfort was significantly higher (p < 0.001) than at the other levels of assistance.

CONCLUSION

In volunteers, the helmet is efficient in ventilation, allowing a Vt increase and RRpes reduction. A significant discomfort was present only at the highest level of assistance; however, it did not affect patient/ventilator interaction.

Pressure-regulated volume control ventilation vs synchronized intermittent mandatory ventilation for very low-birth-weight infants: a randomized controlled trial

OBJECTIVE

To test the hypothesis that pressure-regulated volume control (PRVC), an assist/control mode of ventilation, would increase the proportion of very low-birth-weight infants who were alive and extubated at 14 days of age as compared with synchronized intermittent mandatory ventilation (SIMV).

STUDY DESIGN

Ventilated infants with birth weight of 500 to 1249 g were randomized at less than 6 hours of age either to pressure-limited SIMV or to PRVC on the Servo 300 ventilator (Siemens Electromedical Group, Danvers, Mass). Infants received their assigned mode of ventilation until extubation, death, or meeting predetermined failure criteria.

RESULTS

Mean +/- SD birth weights were similar in the SIMV (888 +/- 199 g, n = 108) and PRVC (884 +/- 203 g, n = 104) groups. No differences were detected between SIMV and PRVC groups in the proportion of infants alive and extubated at 14 days (41% vs 37%, respectively), length of mechanical ventilation in survivors (median, 24 days vs 33 days, respectively), or the proportion of infants alive without a supplemental oxygen requirement at 36 weeks' postmenstrual age (57% vs 63%, respectively). More infants receiving SIMV (33%) failed their assigned ventilator mode than did infants receiving PRVC (20%). Including failure as an adverse outcome did not alter the overall outcome (39% of infants in the SIMV group vs 35% of infants in the PRVC group were alive, extubated, and had not failed at 14 days).

CONCLUSION

In mechanically ventilated infants with birth weights of 500 to 1249 g, using PRVC ventilation from birth did not alter time to extubation.

Volume-targeted versus pressure-limited ventilation in the neonate

BACKGROUND

Inflammation caused by lung overdistension (volutrauma) is thought to be important in the pathogenesis of bronchopulmonary dysplasia (BPD). Preterm infants with variable lung compliance are particularly at risk. Volume-targeted neonatal ventilators have been developed as alternatives to traditional pressure-limited ventilators. They deliver consistent, appropriate tidal volumes with the aim of reducing lung damage. It is suggested that these would provide an effective, safer means of ventilating the newborn infant.

OBJECTIVES

To determine whether volume-targeted ventilation compared with pressure-limited ventilation leads to reduced rates of death and BPD in newborn infants. Secondary objectives were to determine whether use of volume modes affected clinical outcomes such as incidence of airleak, growth, duration of ventilation or cranial ultrasound findings.

SEARCH STRATEGY

The search strategy comprised searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2004), MEDLINE PubMed 1966 to November 2004, and hand searches of reference lists of relevant articles and conference proceedings.

SELECTION CRITERIA

All randomised and quasi-randomised trials comparing the use of volume-targeted versus pressure-limited ventilation in neonates in the first 28 days of life.

DATA COLLECTION AND ANALYSIS

Two authors assessed the methodological quality of eligible trials and extracted data independently. When appropriate, meta-analysis was conducted to provide a pooled estimate of effect. For categorical data the relative risk (RR) and risk difference (RD) were calculated with 95% confidence intervals. Number needed to treat was calculated when RD was statistically significant. Continuous data were analysed using weighted mean difference (WMD).

MAIN RESULTS

Four randomised trials were identified that addressed the outcomes of this review, recruiting a total of 178 preterm infants. All were recruited during the first 72 hours of life. Caregivers and those evaluating the outcomes of trials were not masked. All trials report high rates of follow-up, although one trial with uneven patient distribution may have had some post-randomisation attrition. No significant difference was found for death by hospital discharge, and no trials reported the combined outcome of death or BPD. When secondary outcomes were examined, pooled analysis of the trials showed that volume-targeted ventilation resulted in significant reductions in duration of ventilation [WMD -2.93 days (-4.28, -1.57)] and rates of pneumothorax [typical RR 0.23 (0.07, 0.76), RD -0.11 (-0.20, -0.03), NNT 9]. There was also a significant difference in rates of severe (Grade 3 or 4) intraventricular haemorrhage favouring the volume-targeted group [typical RR 0.32 (0.11, 0.90), RD -0.16 (-0.29, -0.03), NNT 6]. There was a reduction in the incidence of BPD (supplemental oxygen at 36 weeks) amongst surviving infants, of borderline statistical significance [typical RR 0.34 (0.11, 1.05), RD -0.14 (-0.27, 0.00), NNT=7]. No significant differences were found for failure of mode of ventilation, use of neuromuscular paralysis, patent ductus arteriosus, airleak of any sort or pulmonary interstitial emphysema alone, cranial ultrasound abnormalities or periventricular leucomalacia. None of the trials addressed growth, death after discharge from hospital or neurodevelopmental outcome.

AUTHORS' CONCLUSIONS

Although rates of death and BPD were not significantly different between the two ventilator strategies, statistically significant effects favouring volume targeting were shown for some clinically important outcomes. However, the numbers of trials and infants randomised are small and further studies are required to confirm the role of volume targeting in neonatal ventilation.

Treatment adherence and outcomes in flexible vs standard continuous positive airway pressure therapy

STUDY OBJECTIVES

To compare adherence and clinical outcomes between flexible positive airway pressure (PAP) [C-Flex; Respironics; Murraysville, PA] and standard PAP therapy (ie, continuous positive airway pressure [CPAP]).

DESIGN AND SETTING

A controlled clinical trial of CPAP therapy vs therapy using the C-Flex device in participants with moderate-to-severe obstructive sleep apnea. Participants were recruited from and followed up through an academic sleep disorders center.

PARTICIPANTS

Eighty-nine participants were recruited into the study after they had undergone complete in-laboratory polysomnography and before initiating therapy. Participants received either therapy with CPAP (n = 41) or with the C-Flex device (n = 48), depending on the available treatment at the time of recruitment, with those recruited earlier receiving CPAP therapy and those recruited later receiving therapy with the C-Flex device. Follow-up assessments were conducted at 3 months.

MEASUREMENTS AND RESULTS

The groups were similar demographically. The mean (+/- SD) treatment adherence over the 3-month follow-up period was higher in the C-Flex group compared to the CPAP group (weeks 2 to 4, 4.2 +/- 2.4 vs 3.5 +/- 2.8, respectively; weeks 9 to 12, 4.8 +/- 2.4 vs 3.1 +/- 2.8, respectively). Clinical outcomes and attitudes toward treatment (self-efficacy) were also measured. Change in subjective sleepiness and functional outcomes associated with sleep did not improve more in one group over the other. Self-efficacy showed a trend toward being higher at the follow-up in those patients who had been treated with the C-Flex device compared to CPAP treatment.

CONCLUSIONS

Therapy with the C-Flex device may improve overall adherence over 3 months compared to standard therapy with CPAP. Clinical outcomes do not improve consistently, but C-Flex users may be more confident about their ability to adhere to treatment. Randomized clinical trials are needed to replicate these findings.

Bi-level positive airway pressure ventilation reduces the oxygen cost of breathing in long-standing post-polio patients on invasive home mechanical ventilation

BACKGROUND

Today, patients with chronic respiratory failure are commonly treated with non-invasive bi-level positive airway pressure ventilation, supporting spontaneous breathing. However, in conformity with previous clinical routine, many post-polio patients with chronic respiratory failure are still treated with invasive (i.e. via a tracheostomy) controlled mechanical ventilation (CMV). The aim of the study was to investigate the effect of invasive bi-level positive airway pressure ventilation on the work of breathing compared with that during the patients' ordinary CMV and spontaneous breathing without mechanical support.

METHODS

Nine post-polio patients on invasive (tracheostomy) nocturnal CMV were investigated. Work of breathing was analysed by assessing differences in oxygen consumption (VO2) using indirect calorimetry. Hereby, the oxygen cost of breathing during the various ventilatory modes could be estimated and related to one another. Data on energy expenditure were also obtained.

RESULTS

The oxygen cost of breathing decreased by approximately 15% during bi-level positive airway pressure ventilation compared with CMV and spontaneous breathing. There was no difference between predicted (Harris-Benedict equation) and measured energy expenditure.

CONCLUSION

Invasive bi-level positive airway pressure ventilation reduces the oxygen cost of breathing in long-standing tracheostomized post-polio patients, compared with CMV. Furthermore, the Harris-Benedict equation provides a reasonable prediction of energy expenditure in this group of patients.

Benefits at 1 year of nocturnal intermittent positive pressure ventilation in patients with obesity-hypoventi lation syndrome

BACKGROUND

Patients with the obesity-hypoventilation syndrome (OHS) benefit from non-invasive ventilatory support. We assessed the long-term physiopathological response to 12-months of nocturnal ventilatory assistance at home with bi-level positive airway pressure (BiPAP) via nasal mask in patients with this disease.

METHODS

A series of 13 non-consecutive patients diagnosed of OHS (5 men and 8 women) with a mean (SD) age of 61.9 (8) years, underwent the following studies before (baseline) and after 12 months of non-invasive domiciliary mechanical ventilation: arterial blood gases, nocturnal digital pulse oximetry, spirometry, body plethysmography, maximum muscular respiratory pressures and ventilatory pattern with measurement of occlusion pressure (P0.1) before and after hypercapnia. An overnight cardiorespiratory polygraphy was done at baseline.

RESULTS

After 12 months of non-invasive mechanical ventilation, there were significant (P < 0.05) reductions of arterial carbon dioxide tension (PaCO2) and increases in arterial oxygen tension, forced vital capacity and ventilatory response to hypercapnia, as measured by the relationship between changes of P0.1 and PaCO2 (deltaP0.1 / deltaPaCO2) as well as respiratory minute volume (V(E)) and PaCO2 (deltaV(E) / deltaPaCO2). Changes of the PaCO2 correlated significantly with those in the (deltaP0.1 / deltaPaCO2) slope (r = 0.576, P < 0.05).

CONCLUSIONS

The present results confirm that non-invasive home mechanical ventilation is an effective approach for long-term treatment of OHS.

Proportional Assist Ventilation Reduces the Work of Breathing during Exercise at Moderate Altitude

Reducing the work of breathing (WOB) during exercise and thus the oxygen required solely for ventilation may be an option to increase the oxygen available for nonventilatory physiological tasks at altitude. This study evaluated whether pressure support ventilation (PSV) and proportional assist ventilation (PAV) may partially reduce WOB during exercise at altitude. Seven volunteers breathing with either PSV or PAV or without support (control) were examined for WOB, inspiratory pressure time product (iPTP), and (O(2)) before and during pedaling at 160 W for 4 min on an ergometer at an altitude of 2860 m, where barometric pressure and oxygen partial pressure are approximately 30% less than at sea level. PSV and PAV reduced WOB from 4.5 +/- 0.9 J/L(-1)/min(-1) during unsupported breathing to 3.7 +/- 0.4 (p < 0.05) and 3.2 +/- 0.7 (p < 0.01), respectively. iPTP was reduced during PAV (570 +/- 151 cm H(2)O/sec/min(-1), p < 0.01), but not during PSV (727 +/- 116, p = 0.58) compared with unsupported ventilation during exercise (763 +/- 90). During PSV and PAV breathing, higher arterial oxygen saturations (84 +/- 2%, p < 0.05, and 86 +/- 1%, p < 0.01, respectively) were observed compared with control (80 +/- 3%), indicating that PSV and PAV attenuated hypoxemia during exercise at altitude. Total body (O(2)), however, was not reduced during PSV or PAV. In conclusion, both PSV and PAV reduced the WOB during exercise at altitude, but only PAV reduces iPTP. Both modes reduce hypoxemia, which may be due to higher alveolar ventilation or decreased ventilation-perfusion heterogeneity compared to unsupported breathing.

[New therapeutic approaches to COPD]

Classification of severity of the disease is the basis of the therapeutic concept for chronic obstructive lung disease (COPD). Besides pharmacological treatment, preventive measures and rehabilitation with training are the main parts of COPD therapy. Weaning patients of cigarette smoking is of utmost importance in every stage for the course of the disease. Inhalative short acting bronchodilators on demand are the basis of treatment in all stages as well as long acting bronchodilators from stage II on as continuous medication. Theophyllines are of additional importance in higher degrees of the disease. Inhalative steroids are indicated in severe stages III or higher, systemic steroids only during exacerbations as short course therapy. Oxygen long time treatment, intermittent non-invasive ventilation, and operations in some cases are additional therapies.

Long versus short inspiratory times in neonates receiving mechanical ventilation

BACKGROUND

When intermittent positive pressure ventilation (IPPV) was introduced in newborn infants with hypoxic respiratory failure from hyaline membrane disease (HMD), mortality was high and air leaks problematic. This barotrauma was caused by the high peak inspiratory pressures (PIP) required to oxygenate stiff lungs. The primary determinants of mean airway pressure (and thus oxygenation) on a conventional ventilator are the inspiratory time (IT), PIP, positive end expiratory pressure and gas flow rates. In the 1970s uncontrolled studies on a small number of infants demonstrated a benefit in reducing barotrauma using a long IT and slow rates. This strategy was subsequently widely adopted. Current neonatal ventilators have been designed to minimise lung injury but rates of bronchopulmonary dysplasia (BPD) remain high. It is therefore important that the inspiratory time causing least harm is used.

OBJECTIVES

To determine in mechanically ventilated newborn infants whether the use of a long rather than a short IT reduces the rates of death, air leak and BPD.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group (CNRG) was used. Searches of electronic and other databases were performed. These included MEDLINE (1966 - April 2004) and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2003). In order to detect trials that may not have been published, the abstracts of the Society for Pediatric Research, and the European Society for Pediatric Research were searched from 1998 - 2003.

SELECTION CRITERIA

All randomised and quasi-randomised controlled trials enrolling mechanically ventilated infants with or without respiratory pathology evaluating the use of long versus short IT (including randomised crossover studies with outcomes restricted to differences in oxygenation).

DATA COLLECTION AND ANALYSIS

The standard method of the Cochrane Collaboration and its Neonatal Review Group were used. Two authors independently assessed eligibility, and the methodological quality of each trial, and extracted the data. The data were analysed using relative risk (RR) and risk difference (RD) and their 95% confidence intervals. A fixed effect model was used for meta-analyses.

MAIN RESULTS

In five studies, recruiting a total of 694 infants, a long IT was associated with a significant increase in air leak [typical RR 1.56 (1.25, 1.94), RD 0.13 (0.07, 0.20), NNT 8 (5, 14)]. There was no significant difference in the incidence of BPD. Long IT was associated with an increase in mortality before hospital discharge that reached borderline statistical significance [typical RR 1.26 (1.00, 1.59), RD 0.07 (0.00, 0.13)].

REVIEWERS' CONCLUSIONS

Caution should be exercised in applying these results to modern neonatal intensive care, because the studies included in this review were conducted prior to the introduction of antenatal steroids, post natal surfactant and the use of synchronised modes of ventilatory support. Most of the participants had single pathology (HMD) and no studies examined the effects of IT on newborns ventilated for other reasons such as meconium aspiration and congenital heart disease (lungs with normal compliance). However, the increased rates of air leaks and deaths using long ITs are clinically important; thus, infants with poorly compliant lungs should be ventilated with a short IT.

Use of nasal intermittent positive pressure ventilation to avoid intubation in neonates

OBJECTIVE

Nasal intermittent positive pressure ventilation (NIPPV) has widely been used in neonates to prevent extubation failure and apnea. This pilot study was carried out to look at the early use of NIPPV to avoid intubation.

METHODS

The study was carried out over a period of 3 months from August 2003 to October 2003 at the Royal Hospital, Muscat, Sultanate of Oman. The neonates with clinical signs of moderate to severe respiratory distress were given a trial of early NIPPV based on the avoid-intubation protocol. Inclusion, exclusion and failure criteria with general procedure were made clear to all medical and nursing staff and the protocol was posted in the unit for further time to time referral.

RESULTS

A total of 16 neonates met the inclusion criteria for early NIPPV trial. Out of these, 13 (81%) had a successful NIPPV. The mean age of entry was 0.95 hours; however, the mean duration of NIPPV was 23 hours. No NIPPV related complications were noted in the study group.

CONCLUSION

We concluded that NIPPV is an appropriate mode of ventilation in neonates requiring respiratory support. The major advantage of NIPPV is the non-invasive mechanics. It is also less expensive and less labor intensive. Further randomized controlled trials with larger sample size are warranted to confirm our findings.