Continuous Airway Pressure Research Articles

Acute Pulmonary Edema after Simultaneous Bilateral Percutaneous Nephrolithotomy - A case report -

Percutaneous nephrolithotomy (PCNL) is currently the procedure of choice for the removal of large and complex renal calculi. With recent developments in percutaneous access technique and in equipment for the disintegration of calculi, simultaneous bilateral PCNL has become safe. However the complications include hemorrhage, extravasation and absorption of large volumes of irrigation fluid, fever, infection, colonic perforation and pneumothorax. A 46-year-old, 59 kg, female patient in our care developed acute pulmonary edema after simultaneous bilateral PCNL under general anesthesia. The preoperative chest X-ray was normal. The patient recovered following 36 hours of intensive treatment involving fluid restriction, diuretics, sedation and continuous airway pressure ventilation. (Korean J Anesthesiol 2007; 53: 270～3)

Erste Erfahrungen in der prophylaktischen Anwendung von Surfactant bei Patienten mit Lungenerkrankungen in der Herzchirurgie

Background Pulmonary complications are still frequent in the early postoperative course of cardiac surgery using cardiopulmonary bypass (CPB). The objective of the present pilot study is the investigation of three different prophylactic concepts to reduce postoperative pulmonary dysfunction in patients with pre-existing pulmonary disease in comparison to the established concept in cardiovascular surgery. Patients and methods After approval by the local ethics committee, 33 patients were included in this prospective, randomized, open clinical study. The patients were randomly assigned to one of four groups representing the respective ventilation and treatment concepts during CPB: control group [n=9] continuous positive airway pressure (CPAP: 5 cm H 2 O, FiO 2 0.21); ventilation group [n=8] ] low-tidal ventilation (2-4 ml/kg BW, FiO 2 0.21); surfactant group [n = 8] continuous airway pressure (CPAP: 5 cm H 2 O, FiO 2 0.21) and 2 mg/kg BW surfactant; ventilation and surfactant group [n=8] low-tidal ventilation (2-4 ml/kg BW, FiO 2 0.21) combined with 2 mg/kg BW surfactant. The surfactant was installed at the end of CPB under sterile conditions via a catheter directly in the distal trachea, followed by three inspiration-maneuvers (p = 40 mbar). Hemodynamic measurements and blood gas analyses were performed after introduction of anesthesia, after pericardiotomy, at the end of surgery, two hours postoperative and once daily for three days following surgery. Results Biometric data, characteristics of surgery and the results of hemodynamic measurements showed no significant differences between the four groups. All patients tolerated the surfactant treatment without any side effects. The shortest postoperative ventilation time, stay in ICU and stay in hospital were found in the control group (n.s.). The lowest incidence of complications was observed in the control group, that of pulmonary complications in the surfactant group (n.s.). Conclusions Our results demonstrate that neither ventilation nor surfactant can improve the perio-perative reconvalescence. The data of the control group (CPAP alone) confirm the established concept concerning postoperative ventilation time, stay in ICU and stay in hospital.

Intrathoracic pressure regulation improves vital organ perfusion pressures in normovolemic and hypovolemic pigs

The intrathoracic pressure regulator (ITPR) was created to improve hemodynamics by generating continuous negative airway pressure between positive pressure ventilations to enhance cardiac preload in apnoeic animals. In normovolemic and hypovolemic pigs, we tested the hypothesis that continuous negative intrathoracic pressure set at -5 or -10mmHg, interrupted only for intermittent positive pressure ventilations, would decrease intracranial (ICP) and right atrial (RAP) pressure, and increase mean arterial pressure (MAP). Twelve pigs were anesthetized with propofol and ventilated with a bag. The ITPR was used to vary baseline endotracheal pressures (ETPs) for 5min periods in the following sequence: 0, -5, 0, -10, 0mmHg under normovolemic conditions. Six pigs were bled 50% (32.5+/-mL/kg) of their estimated blood volume and the airway pressure sequence was repeated. Six other pigs were bled 35% (22.75+/-mL/kg) of their estimated blood volume and the same airway pressure sequence was repeated. Intracranial, aortic, right atrial pressures, arterial blood gases, end tidal CO(2) (ETCO(2)), were measured. ANOVA was used for statistical analysis. Linear regression analysis was performed for ETP and ICP. Mean arterial and vital organ perfusion pressures were significantly improved and RA pressure significantly decreased with the use of the ITPR; the effect was greater with the more negative ETPs and lower circulating blood volume. The change of ICP was linearly related to the ETP and blood loss: DeltaICP=[1.22-0.84(1-%blood loss/100)]xETP, r(2)=0.88 (in mmHg), p<0.001. There were no adverse device effects and there was a significant increase of ETCO(2) with the use of ITPR. The ITPR decreased RAP and ICP significantly and improved mean arterial and cerebral and coronary perfusion pressures without affecting acid base balance severely. The decrease in ICP was directly proportional to the reduction in intrathoracic pressure. The effects were more pronounced in severe hypovolemic and hypotensive states with more negative ETP pressure.

Early investigation and treatment of obstructive sleep apnoea after acute stroke

Obstructive sleep apnoea (OSA) is an independent risk factor for hypertension, which is a major cause of stroke. The prevalence and associations of OSA in a cohort of stroke patients were studied. The safety and tolerability of early treatment with nasal continuous airways pressure (nCPAP) was also assessed. Consecutive subjects admitted with acute stroke were assessed clinically, radiologically and with scales assessing prior OSA risk, dysphagia and disability. Sleep studies were performed within the first few days of admission using a portable diagnostic system. Twenty-nine of 55 (53%) subjects had evidence of OSA, using an apnoea-hypopnoea index (AHI) of 10 or greater. The AHI was significantly associated with an index of prior OSA symptoms, but not with history of hypertension, degree of dysphagia, or type and severity of stroke. Use of a portable diagnostic system for detecting OSA in the acute stroke setting was well tolerated. OSA is common after acute stroke and exceeds rates seen in control populations of similar age (53% vs. 11%). Early treatment with nCPAP was effective and well tolerated.

Bronchopulmonary dysplasia: old problem, new presentation

This milder form of illness is the most commonly observedin extremely low birth weight infants today.Once lung damage has occurred, these infants mayrequire mechanical ventilation and increased oxygenconcentration for long periods of time with gradual weaningfrom ventilator and oxygen therapy after several weeks ormonths. Infants with more severe BPD may still evolveinto progressive respiratory failure, or even death, as aresult of more severe lung damage and pulmonaryhypertension that can result in cor pulmonale.The reported incidence of BPD varies widely and thisvariation is related to differences in patient susceptibilityand management, but inconsistencies in BPD definitionalso accounts for the variation. The diagnostic criteria forBPD are based on oxygen dependency and this can varydue to differences in altitude, the use of other methods ofrespiratory support such as continuous or intermittentpositive airway pressure and use of drugs that caninfluence gas exchange, such as diuretics, respiratorystimulants or corticosteroids. Perhaps the major problemof using oxygen requirement to define BPD is the variation

Early variable-flow nasal continuous positive airway pressure in infants ⩽1000 grams at birth

To compare the incidence of chronic lung disease (CLD) in extremely low birth weight (ELBW, < or =1000 g) infants before and after the introduction of early, preferential application of nasal continuous airway pressure (NCPAP) utilizing a variable flow delivery system. A retrospective cohort study of ELBW infants 2 years prior to (Pre-early NCPAP, n=96) and 2 years following (Early NCPAP, n=75) the initiation of an early NCPAP policy. There were no significant changes (Pre-early NCPAP vs Early NCPAP) in the incidences of CLD (35 vs 33%, P=0.81) or CLD or death (50 vs 43%, P=0.34). Infants in the Early NCPAP group weaned off mechanical ventilation and supplemental oxygen more rapidly than infants in the Pre-early NCPAP group (hazard ratio (HR) 1.80, P=0.002 and HR 1.69, P=0.01). A policy of early NCPAP has not decreased the incidence of CLD despite a decrease in time to successful tracheal extubation.

Obstructive Sleep Apnoea and Patent Foramen Ovale: Successful Treatment of Symptoms by Percutaneous Foramen Ovale Closure

Obstructive sleep apnoea (OSA) is a common sleep disorder often associated with cardiovascular problems. The role of right to left shunt through a patent foramen ovale (PFO) in OSA is still debated. We report the case of a 42-year-old man with OSA, treated by nocturnal continuous airway pressure, who had a PFO and severe dispnoea and desaturation at exercise. Percutaneous closure of PFO leads to immediate and complete resolution of symptoms. Our report shows for the first time that patients with OSA, PFO, and desaturation at exercise should be considered candidates to PFO closure, even in the absence of cerebral events.

269 Nasal Continuous Positive Airway Pressure Facilitates Early Neonatal Back Transfer

Introduction: Neonatal networks and dedicated intensive care retrieval systems are evolving in the United Kingdom. Early back transfer to step-down level 2 units (as defined by the British Association of Perinatal Medicine [BAPM]) could facilitate more efficient use of tertiary level intensive care cots. Use of nasal continuous airway pressure (nCPAP) during neonatal transportation may allow earlier back transfer of nCPAP dependent babies who would otherwise have to remain at a tertiary centre.Aim: To examine the feasibility of nCPAP for transfer of nCPAP dependent babies to referral units.Methods: In a prospective study between July 2003 and October 2004, we used nCPAP as a means of respiratory support for nCPAP dependent infants during neonatal back-transfer to base/home hospitals.After two weeks, a telephone enquiry was made to each accepting unit to ascertain if any clinical deterioration had followed transfer. We compared the study group with an historical cohort of nCPAP dependent infants who had to wait until they were no longer fully nCPAP dependent before undergoing transfer.Results: Forty one infants in the study group were compared with 58 historical controls. Median (IQR) gestational age was 26 (25–28) weeks and 27 (25–29) weeks respectively, p=0.6. Infants transferred on nCPAP were significantly smaller and younger; at time of transfer, median (IQR) weight was 920g (739–1073g) vs 1128 g (832-1650g), p value< 0.001 and post menstrual age was 29 (28–31) weeks vs 32 (30–35) weeks, p< 0.001.The group transferred on nCPAP spent significantly less time in our neonatal unit: 8 (3–12) days vs 15 (6–33) days, p<0.01. There were no reports of clinical deterioration that could be attributed to the timing or mode of transfer.Conclusion: Transfer of selected small infants using nCPAP appears to be practical and safe and could increase intensive care cot availability.

Volume expansion to increase preload during cardiopulmonary resuscitation (CPR) with continuous airway pressure (CPAP)

Windirsch, M.; Wolcke, B.; Herweling, A.; Markstaller, K.; Werner, C. Author Information

Continuous Airway Pressure Monitoring

Continuous Airway Pressure Monitoring

Acceptance and short-term tolerance of nasal continuous positive airway pressure therapy in elderly patients with obstructive sleep apnea

Short-term compliance of nasal continuous airway pressure (nCPAP) therapy in elderly patients (65 years or older; n = 115) with moderate to severe obstructive sleep apnea was investigated. When nCPAP therapy was offered to elderly patients with an apnea-hypopnea index greater than 20/h, the acceptance rate of nCPAP therapy was 70%. Of those, the short-term tolerance rate of nCPAP therapy (usage over 3 months after initial trial) was 83%. The patients who refused or abandoned nCPAP therapy were less severe (in terms of the apnea-hypopnea index), less sleepy and there were a lower number with hypertension. Considering the short-term compliance of nCPAP therapy reported for middle-aged patients in the literature, it is found that acceptance and short-term tolerance of nCPAP therapy in elderly patients is high, especially in patients with hypertension and excessive daytime sleepiness.

Efectos adversos derivados del tratamiento con ncpap y su relación con la nariz

TThe main problem in the treatment of obstructive sleep apnea syndrome (OSAS) with nasal continuous airway pressure (nCPAP) is the lack of compliance. One of the most important reasons for no compliance is the adverse effects of this treatment. We analyse, prospectively, 182 patients treated with nCPAP in order to show the relationship between previous nasal problems and adverse effects of nCPAP. Sixty percent of the population developed one o more side effects. Of this group, 69% showed nasal septum deviation at first examination in front of 31% that did not showed this problem (p=0,001). In the group of patients with nasal side effects we observed an increase of compliance in 80% of patients treated medically and in 89% of those treated by a septoplasty. We demonstrate that the adverse effects of nCPAP are related to previous nasal problems and, also, that treatment of those problems can achieve an increase in compliance to nCPAP therapy

Continuous distending pressure for respiratory distress syndrome in preterm infants.

Respiratory distress syndrome (RDS) is the single most important cause of morbidity and mortality in preterm infants (Greenough 1998, Bancalari 1992). Intermittent positive pressure ventilation (IPPV) with surfactant is the standard treatment for the condition. The major difficulty with IPPV is that it is invasive, resulting in airway and lung injury and contributing to the development of chronic lung disease. In spontaneously breathing preterm infants with RDS, to determine if continuous distending pressure (CDP) reduces the need for IPPV and associated morbidity without adverse effects. The standard search strategy of the Neonatal Review group was used. This included searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE (1966-Jan. 2000), previous reviews including cross references, abstracts, conference and symposia proceedings, expert informants, journal hand searching mainly in the English language. All trials using random or quasi-random patient allocation of newborn infants with RDS were eligible. Interventions were continuous distending pressure including continuous positive airway pressure (CPAP) by mask, nasal prong, nasopharyngeal tube, or endotracheal tube, or continuous negative pressure (CNP) via a chamber enclosing the thorax and lower body, compared with standard care. Standard methods of the Cochrane Collaboration and its Neonatal Review Group, including independent assessment of trial quality and extraction of data by each author, were used. CDP is associated with a lower rate of failed treatment (death or use of assisted ventilation), overall mortality, and mortality in infants with birthweights above 1500 g. The use of CDP is associated with an increased rate of pneumothorax. In preterm infants with RDS the application of CDP either as CPAP or CNP is associated with some benefits in terms of reduced respiratory failure and reduced mortality. CDP is associated with an increased rate of pneumothorax. The applicability of these results to current practice is difficult to assess, given the outdated methods to administer CDP, low use of antenatal corticosteroids, non-availability of surfactant and the intensive care setting of the 1970s when these trials were done. Where resources are limited, such as in developing countries, CPAP for RDS may have a clinical role. Further research is required to determine the best mode of administration and its role in modern intensive care settings

Dynamic computed tomography: a novel technique to study lung aeration and atelectasis formation during experimental CPR

Objective: To develop an image based technique to study the effect of different ventilatory strategies on lung ventilation and alveolar recruitment during cardiopulmonary resuscitation (CPR). Design: (1) Technical development of the following components: (a) construction of an external chest compression device, which does not interfere with CT imaging, and (b) development of a software tool to detect lung parenchyma automatically and to calculate radiological density parameters. (2) Feasibility studies: three strategies of CPR ventilation were performed and imaged in one animal each (pigs, 25 kg): volume-constant ventilation (VCV), no ventilation, or continuous airway pressure (CPAP). One minute after induction of circulatory arrest inside the CT scanner, external chest compressions started at a rate of 100 cpm, and one of the ventilation modes was initiated. After 1 min, intravenous epinephrine was added as a bolus (40 μg/kg), followed by a continuous infusion (13 μg/kg per min). Six minutes later, dynamic CT acquisitions (temporal resolution: 100 ms) commenced. Simultaneously, arterial blood gases, acid base status and haemodynamics were sampled. Results: Using a modified chest compression device, dynamic CT acquisitions are feasible during closed-chest CPR. In three pilot experiments with different ventilation strategies, the dedicated software tool allowed to quantify ventilated, atelectatic and over-distended fractions of total lung area. VCV showed a large amount of atelectasis, which was recruited during every respiratory cycle. No ventilation led to atelectasis to govern over 50% of the total lung area. CPAP caused less atelectasis as VCV, and no cyclic recruitment and de-recruitment phenomena were observed. Conclusions: We demonstrate a novel experimental set up, which allows quantification of different lung compartments during ongoing CPR and may become useful in comparing the direct pulmonary effects of different ventilatory strategies in the settings of Basic and Advanced Cardiac Life Support.

Repeatability of sites of sleep-induced upper airway obstruction. A 2-night study based on recordings of airway pressure and flow.

To evaluate repeatability of overnight continuous airway pressure and flow recordings for assessment of obstructive sites and their distribution in patients with obstructive sleep apnea (OSA). Open, prospective study of 30 men with sleep-induced obstructive events (apnea and hypopnea). Repeated ambulatory sleep recordings of airway pressure and flow to assess the localization of sites of obstructive events were compared. Obstructive sites were divided into upper (transpalatal) or lower (subpalatal). The exact distribution of obstructive sites was expressed as percentage upper obstructive events. A cut-off at apnea index (AI) = 5 was used for comparison between frequent and infrequent obstructers. Eighty-two percent (14/17) of patients with frequent, and 58% of those with infrequent apneic events maintained their predominant site of obstructive events classified as upper (transpalatal) or lower (subpalatal) [72% (21/29) in the entire group]. We found a significant correlation between recordings for the percentage upper apneic (R = 0.54, P = 0.024, n = 17) and hypopneic (R = 0.59, P = 0.012, n = 17) events in patients with frequent, but not in those with infrequent apneic events. Patients who had the vast majority of obstructive events located at a single site were more stable than those with more evenly distributed obstructive events. Repeatability of sites of obstructive events is influenced by the severity of illness and the degree of upper or lower obstructive predominance. The distribution of sites of obstructive events (classified as mainly "upper"/"lower" or as percent upper obstructive events of all) can be identified with relative confidence in patients who have frequent apneic events (AI > or = 5) or a high degree of upper or lower obstructive predominance and especially in those who have a combination of these two criteria.

Organ recovery from a donor with end-stage renal disease: a case study

As the field of transplantation enters the new millennium, maximizing organs per donor remains one of the greatest challenges of procurement. This case study outlines nontraditional medical management techniques that facilitated the recovery of 5 transplantable organs from a patient with end-stage renal disease. Strategies utilized in this case included the use of continuous veno-venous hemodialysis and airway pressure release ventilation to maximize the outcomes of the donation. Although the use of these strategies is admittedly limited to hospitals where the resources are available, this case study suggests that utilizing available resources in any clinical setting can make more organs available to people on the waiting list for solid organ transplantation.

Continuous Airway pressure monitoring

Continuous Airway pressure monitoring

Limb girdle muscular dystrophy type 2A presenting with cardiac arrest

The occurence of respiratory failure in progressive neuromuscular disorders is well recognized. This failure is observed most commonly in Duchenne dystrophy but sometimes occurs in Becker’s, limb-girdle, and facioscapulohumeral dystrophies. Patients usually present acutely or subacutely with cyanosis and cor pulmonale, with severe decompensation often being precipitated by an acute intercurrent infection. However, cardiopulmonary arrest is an uncommon presentation. A male diagnosed with limb-girdle muscular dystrophy type 2A who presented with cardiopulmonary arrest that was precipitated by an upper respiratory tract infection is presented. The nocturnal application of noninvasive intermittent positive pressure ventilation with a bilevel positive airway pressure (Bi-PAP) device improved his symptoms and quality of life without resorting to more-invasive and more-restrictive forms of support. This report demonstrates an unusual presentation of limb-girdle muscular dystrophy and documents that nocturnal nasal administration of continuous airway pressure using the Bi-PAP device may be sufficient to maintain adequate ventilation in such patients.

Respiratory impedance response to continuous negative airway pressure in awake controls and OSAS

The aim of the study was to determine whether the response of respiratory impedance (Zrs) to decreasing levels of continuous negative airway pressure (CNAP) during wakefulness, differs in controls and subjects with obstructive sleep apnoea syndrome (OSAS). Zrs was measured by the forced oscillation technique (4-32 Hz) in 15 controls and 21 patients with OSAS (apnoea/hypopnoea index >20 per sleep hour) with normal lung function, in the basal state and with application of decreasing CNAP of -5, -10, and -15 hPa. Respiratory resistance was extrapolated to 0 Hz (R0) and estimated at 16 Hz (R16) by linear regression analysis of respiratory resistive impedance versus frequency. Respiratory elastance (Ers) and inertance (Irs) were estimated by multilinear regression analysis of respiratory reactance versus frequency, and resonance frequency (RF) was determined as RF=(1/2pi)(Ers/Irs)0.5. In both groups, R0, R16, Ers and RF significantly increased as the CNAP level decreased (p <0.0001 for all). R0, Ers, and RF increased significantly more in OSAS than in controls (p < 0.01, 0.001, and 0.0001, respectively), independently of the severity of obesity. Receiver operator characteristic curves showed that the parameter which best detected OSAS was RF, with a sensitivity of 81% and 93% specificity for the 13.6 Hz cut-off point. The results of the present study suggest that the response of respiratory impedance to decreasing continuous negative airway pressure levels, might allow detection of obstructive sleep apnoea syndrome in subjects with normal lung function.

A Long-term Randomized, Cross-over Comparison of Auto-titrating and Standard Nasal Continuous Airway Pressure

This study is a 12-week randomized, cross-over, single-blind comparison of the tolerance, compliance, and symptomatic improvement obtained with standard nasal continuous positive airway pressure (CPAP) vs. an auto-titrating, self-adjusting device (APAP). Sixty newly diagnosed patients, 53 with obstructive sleep apnea (OSA) and seven with upper airway resistance syndrome were studied. Thirty-nine patients (65%) completed the 24-week protocol. Data were complete in 33. In these 33 patients CPAP and APAP reduced the Epworth Sleepiness score from 15+/-1 (+/-SEM) to 8+/-1 and 9+/-1 respectively (both <0.0001 from baseline but NS between modes). The APAP average pressure was lower than the CPAP pressure, 6.4+/-0.4 and 10.6+/-0.4 cm H20, respectively. The average daily machine use was greater with APAP, 6.0+/-0.3 hrs. versus 5.5+/-0.3 hrs. with CPAP (P < 0.04). The number of days of machine use, and the pattern of use were not different between CPAP and APAP. A higher proportion of patients who did not complete the study was randomized to CPAP for their initial treatment period. This study showed that: 1) CPAP and APAP produced an equivalent improvement in daytime sleepiness, 2) APAP pressure was lower than CPAP pressure, 3) patients wore the APAP device longer during nights they used the pressure support system, and 4) patients who began the study with APAP were more prone to continue treatment. We conclude that APAP was better tolerated and used a greater number of hours than CPAP, but the extent of improvement in excessive daytime sleepiness was similar between the two modes of therapy.