Use of a nasal continuous positive airway pressure mask in the treatment of postoperative atelectasis in aortocoronary bypass surgery

Prophylactic noninvasive respiratory support in the immediate postoperative period after cardiac surgery - a systematic review and network meta-analysis

BACKGROUND

Noninvasive respiratory support has been increasingly applied in the immediate postoperative period to prevent postoperative pulmonary complications (PPCs). However, the optimal approach remains uncertain. We sought to evaluate the comparative effectiveness of various noninvasive respiratory strategies used in the immediate postoperative period after cardiac surgery.

METHODS

We conducted a frequentist random-effect network meta-analysis (NMA) of randomized controlled trials (RCTs) comparing the prophylactic use of noninvasive ventilation (NIV), continuous positive airway pressure (CPAP), high flow nasal cannula (HFNC), or postoperative usual care (PUC) in the immediate postoperative period after cardiac surgery. Databases were systematically searched through September 28, 2022. Study selection, data extraction, and quality assessment were performed in duplicate. The primary outcome was the incidence of PPCs.

RESULTS

Sixteen RCTs enrolling 3011 patients were included. Compared with PUC, NIV significantly reduced the incidence of PPCs [relative risk (RR) 0.67, 95% confidence interval (CI): 0.49 to 0.93; absolute risk reduction (ARR) 7.6%, 95% CI: 1.6-11.8%; low certainty] and the incidence of atelectasis (RR 0.65, 95% CI: 0.45 to 0.93; ARR 19.3%, 95% CI: 3.9-30.4%; moderate certainty); however, prophylactic NIV was not associated with a decreased reintubation rate (RR 0.82, 95% CI: 0.29 to 2.34; low certainty) or reduced short-term mortality (RR 0.64, 95% CI: 0.16 to 2.52; very low certainty). As compared to PUC, the preventive use of CPAP (RR 0.85, 95% CI: 0.60 to 1.20; very low certainty) or HFNC (RR 0.74, 95% CI: 0.46 to 1.20; low certainty) had no significant beneficial effect on the incidence of PPCs, despite exhibiting a downward trend. Based on the surface under the cumulative ranking curve, the highest-ranked treatment for reducing the incidence of PPCs was NIV (83.0%), followed by HFNC (62.5%), CPAP (44.3%), and PUC (10.2%).

CONCLUSIONS

Current evidence suggest that the prophylactic use of NIV in the immediate postoperative period is probably the most effective noninvasive respiratory approach to prevent PPCs in patients undergoing cardiac surgery. Given the overall low certainty of the evidence, further high-quality research is warranted to better understand the relative benefits of each noninvasive ventilatory support.

CLINICAL TRIAL REGISTRATION

PROSPERO, https://www.crd.york.ac.uk/prospero/ , registry number: CRD42022303904.

Risk factors for postoperative pulmonary complications in children with severely compromised pulmonary function secondary to severe scoliosis

OBJECTIVES

After corrective surgery for scoliosis, postoperative pulmonary complications lead to increases in morbidity, length of hospital stay (LOS) and mortality. This study aimed to identify associations with such respiratory complications, and to assess the utility of noninvasive ventilation (NIV) in children with severe scoliosis METHODS: This retrospective cohort study included all children aged ≤17 years who underwent spinal surgery for scoliosis between January 2009 and January 2012 at a quaternary pediatric hospital. Data were collated regarding polysomnography (PSG) and NIV use, before and after corrective surgery. Factors associated with severely compromised pulmonary function (SCPF) were established and correlations with the occurrence of postoperative pulmonary complications and LOS were identified.

RESULTS

Altogether, 133 children had corrective surgery for scoliosis, aged 12.7 (range: 2-17) years at operation. Scoliosis causes were identified as: idiopathic (39.8%), neuromuscular disease (32.2%), syndrome (15.7%), and congenital (12%). Correlates with SCPF (forced vital capacity [FVC] <40% predicted, n = 10) included markers of sleep hypoventilation, including serum bicarbonate ≥29 mmol/L, morning pCO₂  > 50mm Hg (P = .003), and overnight, episodic CO₂ retention of >7 mm Hg. Using these parameters an additional eight children with SCPF were identified making a total of 18 out of 133 (13.5%) of the patients. Postoperative pulmonary complications were seen in 24 children (18%) and their occurrence correlated with higher Cobb angle (>90°), lower pulmonary function (FVC), higher serum bicarbonate and underlying neuromuscular disease. Amongst the 18 children with SCPF, regular use of NIV preoperatively was associated with reduced rate of postoperative pulmonary complications (P = .02) and reduced LOS by 6.4 days (P = .01).

CONCLUSION

Nocturnal hypoventilation on PSG identifies children with SCPF. Use of NIV in children with SCPF was linked to fewer postoperative pulmonary complications and reduced duration of hospital stay.

Effects of non-invasive ventilation in subjects undergoing cardiac surgery on length of hospital stay and cardiac-pulmonary complications: a systematic review and meta-analysis

Background

Cardiac surgery often leads to pulmonary complications. Non-invasive ventilation (NIV) is a mechanical ventilation modality that may help to prevent the pulmonary complications, and the role of the prophylactic use of NIV in patients after cardiac surgery remains controversial.

Methods

We searched PubMed, Embase, Web of Science and Cochrane Central for randomized controlled trials comparing the use of NIV (continues positive airway pressure or bi-level positive airway pressure) with standard treatment in post-cardiac surgery subjects without language restriction. Two investigators screened the eligible studies up to July, 2019. Meta-analysis using random effect model or fixed effect model was conducted for pulmonary complications, mortality, rate of reintubation and cardiac complications, and mean difference (MD) or standard mean difference for length of hospital stay and length of ICU stay.

Results

We included nine randomized controlled trails with 830 subjects. The use of NIV failed to reduce the risk of pulmonary complications, including atelectasis [risk rate (RR) 0.60; 95% confidence interval (CI): 0.28 to 1.28, P=0.19] and pneumonia (RR 0.27; 95% CI: 0.05 to 1.64, P=0.16). However, it has shortened the length of ICU stay (MD -1.00 h, 95% CI: -1.38 to -0.63, P<0.00001) and the length of hospital stay (MD -1.00 d, 95% CI: -1.12 to -0.87, P<0.00001). NIV also failed to reduce the rate of reintubation (RR 0.68; 95% CI: 0.21 to 2.26, P=0.53) or the risk of cardiac complications (RR 0.81; 95% CI: 0.59 to 1.13, P=0.22).

Conclusions

The prophylactic use of NIV immediately in post-cardiac subjects who underwent cardiac surgery might be able to shorten the length of hospital stay and the length of ICU stay, but it has no significant effect on pulmonary complications, rate of reintubation or cardiac complications.

Prophylactic Noninvasive Ventilation Versus Conventional Care in Patients After Cardiac Surgery

BACKGROUND

Cardiac surgery can be accompanied by postoperative complications, which are associated with increased postoperative morbidity and mortality. Therefore, it is necessary to investigate the effect of prophylactic noninvasive ventilation (NIV) after extubation versus conventional pulmonary care on complications after cardiac surgery.

MATERIALS AND METHODS

An electronic search of PubMed, Cochrane Library, Ovid, and EMBASE was conducted to find randomized controlled trials which compared the effect of prophylactic NIV with controlled strategies on complications and which were published before April 2018.

RESULTS

Ten studies (1011 patients) were included in the final analysis. The atelectasis rate was 32.6% in the prophylactic-NIV group, which was lower than that in the control group (48.71%). Prophylactic NIV could lower the rate of atelectasis, reintubation, and other respiratory complications (pleural effusion, pneumonia, and hypoxia) (odds ratio = 0.43, 0.33, and 0.45; 95% confidence interval: 0.21-0.88, 0. 13-0.84, 0.27-0.75; P = 0.02, 0.02, and 0.002, respectively). The effect on cardiac and distal organ complications (P = 0.07) and hospital mortality (P = 0.62) might be limited.

CONCLUSIONS

Prophylactic NIV is associated with a lower rate of postoperative pulmonary complications. The effect on the other complications and hospital mortality might be limited. Further evidence with randomized controlled trials can discern the benefits.

Prolonged use of noninvasive positive pressure ventilation after extubation among patients in the intensive care unit following cardiac surgery: The predictors and its impact on patient outcome

This retrospective, observational cohort study aimed to determine the independent risk factors and impact of prolonged non-invasive positive pressure ventilation (NIPPV) after extubation among patients in the intensive care unit following cardiac surgery. Patients who received prophylactic NIPPV after extubation were categorized into prolonged (NIPPV duration >3 days, n = 83) and non-prolonged groups (NIPPV duration ≤3 days, n = 105). The perioperative characteristics and hospital outcomes were recorded. The multivariate analyses identified the preoperative residual volume/total lung capacity (RV/TLC) ratio (adjusted odds ratio [AOR]: 1.10; 95% CI:1.01–1.19, p = 0.022) and postoperative acute kidney injury (AKI) with Kidney Disease Improving Global Outcomes (KDIGO) stage 2–3, 48 h after surgery (AOR: 3.87; 95% CI:1.21–12.37, p = 0.023) as independent predictors of prolonged NIPPV. Patients with both RV/TLC ratio > 46.5% and KDIGO stage 2–3 showed a highly increased risk of prolonged NIPPV (HR 27.17, p = 0.010), which was in turn associated with higher risk of postoperative complications and prolonged ICU and hospital stays. Preoperative RV/TLC ratio and postoperative AKI could identify patients at higher risk for prolonged NIPPV associated with poor outcomes. These findings may allow early recognition of patients who are at a higher risk for prolonged NIPPV, and help refine the perioperative management and critical care.

Noninvasive Ventilation During Immediate Postoperative Period in Cardiac Surgery Patients: Systematic Review and Meta-Analysis

OBJECTIVE

To verify the effectiveness of noninvasive ventilation compared to conventional physiotherapy or oxygen therapy in the mortality rate and prevention of pulmonary complications in patients during the immediate postoperative period of cardiac surgery.

METHODS

Systematic review and meta-analysis recorded in the International Prospective Register of Ongoing Systematic Reviews (number CRD42016036441). The research included the following databases: MEDLINE, Cochrane Central, PEDro, LILACS and manual search of the references of studies published until March 2016. The review included randomized controlled trials with patients during the immediate postoperative period of cardiac surgery, which compared the use of noninvasive ventilation, BiLevel modes, continuous positive airway pressure, intermittent positive pressure breathing and positive pressure ventilation with conventional physiotherapy or oxygen therapy, and assessed the mortality rate, occurrence of pulmonary complications (atelectasis, pneumonia, acute respiratory failure, hypoxemia), reintubation rate, ventilation time, time spent in the intensive care unit (ICU), length of hospital stay and partial pressure of oxygen.

RESULTS

Among the 479 selected articles, ten were included in the systematic review (n=1050 patients) and six in the meta-analysis. The use of noninvasive ventilation did not significantly reduce the risk for atelectasis (RR: 0.60; CI95% 0.28-1.28); pneumonia (RR: 0.20; CI95% 0.04-1.16), reintubation rate (RR: 0.51; CI95%: 0.15-1.66), and time spent in the ICU (-0.04 days; CI95%: -0.13; 0.05).

CONCLUSION

Prophylactic noninvasive ventilation did not significantly reduce the occurrence of pulmonary complications such as atelectasis, pneumonia, reintubation rate and time spent in the ICU. The use is still unproven and new randomized controlled trials should be carried out.

Effectiveness of prophylactic non-invasive ventilation on respiratory function in the postoperative phase of pediatric cardiac surgery: a randomized controlled trial

Objective

To evaluate the effectiveness of prophylactic, non-invasive ventilation (NIV) on respiratory function in seven- to 16-year-old children in the post-operative phase of cardiac surgery.

Method

A randomized, controlled trial with 50 children who had undergone cardiac surgery with median sternotomy. After extubation, patients were randomly assigned to one of two groups: control group (n=26), which received instructions regarding posture, early ambulation, and cough stimulation, and CPAP group (continuous positive airway pressure; n=24), which received the same instructions as the control group and CPAP=10 cmH₂0 twice daily for 30 minutes from the 1^st to the 5^th post-operative day (POD). As a primary outcome, lung function was evaluated before and on the 1^st, 3^rd, and 5^th PODs with measures of respiratory rate (RR), tidal volume (TV), slow vital capacity (SVC), inspiratory capacity (IC), minute volume (MV), peak expiratory flow (PEF), and maximal inspiratory pressure (MIP). As secondary outcomes, the time of hospitalization and intensive care were recorded. A mixed, linear regression model and z-test were used to analyze respiratory function, considering p<0.05.

Results

All variables, except RR and MV, showed a significant drop on the 1^st POD, with gradual recovery; however, only MIP had returned to pre-operative values on the 5^th POD in both groups. The RR showed a significant increase on the 1^st POD, with a gradual reduction but without returning to baseline. In the intergroup analysis, significant improvement (p=0.04) was observed only in PEF in the CPAP group on the 1^st DPO. The length of hospitalization and intensive care showed no significant differences.

Conclusion

NIV was safe and well accepted in this group of patients, and the protocol used was effective in improving PEF on the 1^st DPO in the CPAP group.

Efficacy and safety of noninvasive ventilation in patients after cardiothoracic surgery: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Noninvasive ventilation (NIV) is a promising therapeutic strategy after cardiothoracic surgery. This study aimed to meta-analyze the efficacy and safety of NIV as compared to conventional management after cardiothoracic surgery.

METHODS

PubMed, EMBASE, and Cochrane Library databases were searched for randomized controlled trials (RCTs) comparing NIV with conventional management after cardiothoracic surgery. Relative risk (RR), standard mean difference (SMD), and 95% confidence intervals (CIs) were used to measure the efficacy and safety of NIV using random-effects model. Heterogeneity was evaluated using the Q statistic.

RESULTS

This study included 14 RCTs (1740 patients) for the evaluation of efficacy and safety of NIV as compared to conventional management after cardiothoracic surgery. Overall, NIV had minimal effect on the risk of mortality (RR: 0.64; 95% CI: 0.36-1.14; P = 0.127), endotracheal intubation (RR: 0.52; 95% CI: 0.24-1.11; P = 0.090), respiratory (RR: 0.70; 95% CI: 0.47-1.30; P = 0.340), cardiovascular (RR: 0.81; 95% CI: 0.54-1.22; P = 0.306), renal (RR: 0.70; 95% CI: 0.26-1.92; P = 0.491), and other complications (RR: 0.72; 95% CI: 0.38-1.36; P = 0.305), respiratory rate (SMD: -0.10; 95% CI: -1.21-1.01; P = 0.862), heart rate (SMD: -0.27; 95% CI: -0.76-0.22; P = 0.288), PaO2/FiO2 ratio (SMD: 0.34; 95% CI: -0.17-0.85; P = 0.194), PaCO2 (SMD: 0.83; 95% CI: -0.12-1.77; P = 0.087), systolic pressure (SMD: -0.04; 95% CI: -0.25-0.17; P = 0.700), pH (SMD: -0.01; 95% CI: -0.44-0.43; P = 0.974), length of ICU stay (SMD: -0.19; 95% CI: -0.47-0.08; P = 0.171), and hospital stay (SMD: -0.31; 95% CI: -1.00-0.38; P = 0.373). Sensitivity analysis showed that NIV was associated with higher levels of PaO2/FiO2 ratio (SMD: 0.52; 95% CI: 0.00-1.05; P = 0.048) and lower risk of endotracheal intubation (RR: 0.38; 95% CI: 0.22-0.66; P = 0.001).

CONCLUSION

As compared to conventional management, the use of NIV after cardiothoracic surgery improved patient's oxygenation and decreased the need for endotracheal intubation, without significant complications.

Continuous Positive Airway Pressure Versus Oxygen Therapy in the Cardiac Surgical Ward: A Randomized Trial

BACKGROUND

Noninvasive ventilation (NIV) is a common technique to manage patients with acute respiratory failure in the intensive care unit. However, use of NIV in general wards is less well described. The authors' aim was to demonstrate efficacy of NIV, applied in a cardiac surgery ward, in improving oxygenation in patients who developed hypoxemic acute respiratory failure after being discharged from the intensive care unit.

DESIGN

Randomized, open-label trial.

SETTING

University hospital.

PARTICIPANTS

Sixty-four patients with hypoxemia (PaO₂/F_IO₂ ratio between 100 and 250) admitted to the main ward after cardiac surgery.

INTERVENTIONS

Patients were randomized to receive standard treatment (oxygen, early mobilization, a program of breathing exercises and diuretics) or continuous positive airway pressure in addition to standard treatment. Continuous positive airway pressure was administered 3 times a day for 2 consecutive days. Every cycle lasted 1 to 3 hours. All patients completed their 1-year follow-up. Data were analyzed according to the intention-to-treat principle.

MEASUREMENTS AND MAIN RESULTS

The primary endpoint was the number of patients with PaO₂/F_IO₂<200 48 hours after randomization. Continuous positive airway pressure use was associated with a statistically significant reduction in the number of patients with PaO₂/F_IO₂<200 (4/33 [12%] v 14/31 [45%], p = 0.003). One patient in the control group died at the 30-day follow-up.

CONCLUSIONS

Among patients with acute respiratory failure following cardiac surgery, administration of continuous positive airway pressure in the main ward was associated with improved respiratory outcome. This was the first study that was performed in the main ward of post-surgical patients with acute respiratory failure.

Postoperative Noninvasive Ventilation Following Cardiothoracic Surgery

Postoperative pulmonary complications following cardiac and thoracic surgery are common and associated with significant morbidity and mortality. Noninvasive ventilation has emerged as a successful and well-validated strategy to treat various acute medical conditions. More recently, noninvasive ventilation has been studied in selective surgical patient populations with the goal of preventing postoperative complications and treating acute respiratory failure. In this clinical review, we will briefly examine the incidence of pulmonary complications following cardiothoracic surgery and the physiology and mechanics of acute respiratory failure and noninvasive ventilation. We then present a systematic review of the indications, patient selection, and current literature investigating the specific use of noninvasive ventilation in this population.

Protection strategies during cardiopulmonary bypass: ventilation, anesthetics and oxygen

PURPOSE OF REVIEW

To provide an update of research findings regarding the protection strategies utilized for patients undergoing cardiopulmonary bypass (CPB), including perioperative ventilatory strategies, different anesthetic regimens, and inspiratory oxygen fraction. The article will review and comment on some of the most important findings in this field to provide a global view of strategies that may improve patient outcomes by reducing inflammation.

RECENT FINDINGS

Postoperative complications are directly related to ischemia and inflammation. The application of lung-protective ventilation with lower tidal volumes and higher positive end-expiratory pressure reduces inflammation, thereby reducing postoperative pulmonary complications. Although inhalation anesthesia has clear cardioprotective effects compared with intravenous anesthesia, several factors can interfere to reduce cardioprotection. Hyperoxia up to 0.8 FiO(2) may confer benefits without increasing oxidative stress or postoperative pulmonary complications. During the early postoperative period, inhalation anesthesia prior to extubation and the application of preventive noninvasive ventilation may reduce cardiac and pulmonary complications, improving patients' outcomes.

SUMMARY

Lung-protective mechanical ventilation, inhalation anesthesia, and high FiO(2) have the potential to reduce postoperative complications in patients undergoing CPB; however, larger, well powered, randomized control trials are still needed.

Direct extubation onto high-flow nasal cannulae post-cardiac surgery versus standard treatment in patients with a BMI ≥30: a randomised controlled trial

PURPOSE

Patients with a body mass index (BMI) ≥30 kg/m(2) experience more severe atelectasis following cardiac surgery than those with normal BMI and its resolution is slower. This study aimed to compare extubation of patients post-cardiac surgery with a BMI ≥30 kg/m(2) onto high-flow nasal cannulae (HFNC) with standard care to determine whether HFNC could assist in minimising post-operative atelectasis and improve respiratory function.

METHODS

In this randomised controlled trial, patients received HFNC or standard oxygen therapy post-extubation. The primary outcome was atelectasis on chest X-ray. Secondary outcomes included oxygenation, respiratory rate (RR), subjective dyspnoea, and failure of allocated treatment.

RESULTS

One hundred and fifty-five patients were randomised, 74 to control, 81 to HFNC. No difference was seen between groups in atelectasis scores on Days 1 or 5 (median scores = 2, p = 0.70 and p = 0.15, respectively). In the 24-h post-extubation, there was no difference in mean PaO2/FiO2 ratio (HFNC 227.9, control 253.3, p = 0.08), or RR (HFNC 17.2, control 16.7, p = 0.17). However, low dyspnoea levels were observed in each group at 8 h post-extubation, median (IQR) scores were 0 (0-1) for control and 1 (0-3) for HFNC (p = 0.008). Five patients failed allocated treatment in the control group compared with three in the treatment group [Odds ratio 0.53, (95 % CI 0.11, 2.24), p = 0.40].

CONCLUSIONS

In this study, prophylactic extubation onto HFNC post-cardiac surgery in patients with a BMI ≥30 kg/m(2) did not lead to improvements in respiratory function. Larger studies assessing the role of HFNC in preventing worsening of respiratory function and intubation are required.

Routine pre-operative focused ultrasonography by anesthesiologists in patients undergoing urgent surgical procedures

BACKGROUND

Unexpected cardiopulmonary complications are well described during surgery and anesthesia. Pre-operative evaluation by focused cardiopulmonary ultrasonography may prevent such mishaps. The aim of this study was to determine the frequency of unexpected cardiopulmonary pathology with focused ultrasonography in patients undergoing urgent surgical procedures.

METHODS

We performed pre-operative focused cardiopulmonary ultrasonography in patients aged 18 years or above undergoing urgent surgical procedures at pre-defined study days. Known and unexpected cardiopulmonary pathology was recorded, and subsequent changes in the anesthesia technique or supportive actions were registered.

RESULTS

A total of 112 patients scheduled for urgent surgical procedures were included. Their mean age (standard deviation) was 62 (21) years. Of these patients, 24% were American Society of Anesthesiologists (ASA) class 1, 39% were ASA class 2, 32% were ASA class 3, and 4% were ASA class 4. Unexpected cardiopulmonary pathology was disclosed in 27% [95% confidence interval (CI) 19-36] of the patients and led to a change in anesthesia technique or supportive actions in 43% (95% CI 25-63) of these. Unexpected pathology leading to changes in anesthesia technique or supportive actions was only disclosed in a group of patients above the age of 60 years and/or in ASA class ≥ 3.

CONCLUSION

Focused cardiopulmonary ultrasonography disclosed unexpected pathology in patients undergoing urgent surgical procedures and induced changes in the anesthesia technique or supportive actions. Pre-operative focused ultrasonography seems feasible in patients above 60 year and/or with physical limitations but not in young, healthy individuals.

Examining interrater reliability and validity of a paediatric cardiopulmonary physiotherapy discharge tool

PURPOSE

To determine the interrater reliability (IRR) of the individual items in the Paediatric Cardiopulmonary Physiotherapy (CPT) Discharge Tool. This tool identifies six critical items that physiotherapists should consider when determining a paediatric patient's readiness for discharge from CPT after upper-abdominal, cardiac, or thoracic surgery: oxygen saturation, mobility, secretion retention, discharge planning, auscultation, and signs of respiratory distress.

METHODS

A total of 33 paediatric patients (ages 2 to <19 years) who received at least 1 day of CPT following cardiac, thoracic, or upper-abdominal surgery were independently assessed using the Paediatric CPT Discharge Tool by two designated assessors, who assessed each patient within 4 hours of each other.

RESULTS

Kappa analysis showed the following levels of interrater agreement for the six items of the Paediatric CPT Discharge Tool: Oxygen Saturation, excellent (κ=0.80); Mobility, substantial (κ=0.62); Secretion Clearance, moderate (κ=0.39); Discharge Planning, fair (κ=0.37); and Auscultation and Respiratory Distress, poor (κ=0.24 and κ=-0.08, respectively).

CONCLUSION

Several of the items in the Paediatric CPT Discharge Tool demonstrate good IRR. The discharge tool is ready for further psychometric testing, specifically validity testing.

The role of non-invasive positive pressure ventilation in post-extubation respiratory failure: An evaluation using meta-analytic techniques

Background:

The use of non-invasive positive pressure ventilation (NIPPV) in post-extubation respiratory failure is not well-established. Meta-analytic techniques were used to assess the effects of prophylactic application of NIPPV (prior to the development of respiratory failure) and therapeutic application of NIPPV (subsequent to the development of respiratory failure).

Materials and Methods:

Randomized controlled trials (RCTs) from 1966 to May 2010 were identified using electronic databases. RCTs, which reported the use of NIPPV in post-extubation respiratory failure with defined assessable endpoints: reintubation, mortality and length of stay, were included.

Results:

Reintubation was the primary outcome, mortality and lengths of stay were the secondary outcomes. Risk ratios (RR) were calculated for discrete outcomes and weighted mean differences (WMD) for continuous measures. There were 13 trials with 1420 patients; 9 prophylactic with 861 patients and 4 therapeutic with 559 patients. In the prophylactic group, NIPPV was associated with lower rates of reintubation: RR 0.53 (95% confidence interval [CI], 0.28-0.98), P = 0.04. In the therapeutic group, NIPPV showed a null effect on reintubation: RR 0.79 (95% CI, 0.50-1.25), P = 0.31. The analysis on the secondary outcomes suggested significant reduction of hospital mortality with prophylactic application of NIPPV: RR 0.62 (95% CI 0.4-0.97), P = 0.03, with no effect on the other outcomes. Therapeutic application of NIPPV reduced intensive care unit length of stay: WMD −1.17 (95% CI −2.82 to −0.33), P = 0.006, but no effect on the other secondary outcomes.

Conclusions:

The results of this review suggested prophylactic NIPPV was beneficial with respect to reintubation and the therapeutic use of NIPPV showed a null effect.

Noninvasive respiratory support in the perioperative period

PURPOSE OF REVIEW

Pulmonary complications ranging from atelectasis to acute respiratory failure are common causes of poor perioperative outcomes. As the surgical population becomes increasingly at risk for pulmonary dysfunction due to increasing age and weight, development of an approach toward respiratory compromise in these patients is becoming ever more important. Given the utility of noninvasive respiratory support (NRS) in acute respiratory failure, it is likewise likely to also be important in the perioperative period.

RECENT FINDINGS

NRS is evaluated from preoperative risk assessment to its use in prevention and treatment of acute respiratory failure. Data supporting intraoperative use of NRS including preinduction continuous positive airway pressure and postextubation NRS for high-risk individuals and surgeries are examined. Timing and duration of NRS is also addressed. Finally, NRS is proposed for treatment for postoperative acute respiratory failure as an alternative to invasive rescue maneuvers.

SUMMARY

Noninvasive respiratory support should be considered an important adjunct in perioperative pulmonary care. Usage should be individually tailored in regard to timing and application modality specific to patient and surgical circumstances. More studies are needed, however, to determine the relationship demonstrated between short-term improvements in lung function and long-term outcomes.

Postoperative noninvasive ventilation

General anesthesia and surgery are associated with changes in the shape of the chest that result in atelectasis, a major factor in the development of postoperative respiratory failure. Postoperative noninvasive positive pressure ventilation (NIPPV) has been shown to improve oxygenation and ventilation for high-risk patients. NIPPV has been used as rescue therapy for patients developing acute respiratory distress postoperatively, and appears to be most frequently successful in patients whose problem is atelectasis or obesity. Failure to respond to NIPPV after 20 minutes is usually an indication of intubation, mechanical ventilation, and transfer to the intensive care unit.

Impact of alveolar recruitment maneuver in the postoperative period of videolaparoscopic bariatric surgery

BACKGROUND AND OBJECTIVES

Pulmonary complications in bariatric surgery are common and, therefore, alveolar recruitment maneuvers (ARM) have been used to prevent or reduce them in the postoperative period (POP). The aim of this study was to evaluate the impact of ARM performed intraoperatively in patients undergoing bariatric surgery by videolaparoscopy in the incidence of postoperative pulmonary complications.

METHODS

Randomized clinical trial with 30 patients divided into control group (CG) and experimental group (EG), with analysis of spirometric, ventilatory, hemodynamic, and radiographic variables. ARM was performed in EG with positive end expiratory pressure of 30 cmH₂O and inspiratory plateau pressure of 45 cmH₂O for 2 minutes after pneumoperitoneum deflation.

RESULTS

We observed a significant decrease in spirometric values (p ≤ 0.001) and higher incidence of pulmonary complications on chest radiograph (p=0.02) in CG, as well as significant improvement in dyspnoea Borg scale (p ≤ 0.001) in EG.

CONCLUSIONS

We conclude that ARM is a safe and effective technique when used for prevention of pulmonary complications in patients undergoing bariatric surgery, resulting in more favorable radiological and spirometric findings in the experimental group compared to the control group in the PO.

Non-invasive ventilation in postoperative patients: a systematic review

BACKGROUND

Postoperative pulmonary complications, generally defined as any pulmonary abnormality occurring in the postoperative period, are still a significant issue in clinical practice increasing hospital length of stay, morbidity and mortality. Non-invasive ventilation (NIV), primarily applied in cardiogenic pulmonary edema, decompensated COPD and hypoxemic pulmonary failure, is nowadays also used in perioperative settings.

OBJECTIVE

Investigate the application and results of preventive and therapeutic NIV in postsurgical patients.

DESIGN

A systematic review.

DATA SOURCES

Medical literature databases were searched for articles about "clinical trials," "randomized controlled trials" and "meta-analyses." The keywords "cardiac surgery," "thoracic surgery," "lung surgery," "abdominal surgery," "solid organ transplantation," "thoraco-abdominal surgery" and "bariatric surgery" were combined with any of these: "non-invasive positive pressure ventilation," "continuous positive airway pressure," "bilevel ventilation," "postoperative complications," "postoperative care," "respiratory care," "acute respiratory failure," "acute lung injury" and "acute respiratory distress syndrome."

RESULTS

Twenty-nine articles (N=2,279 patients) met the inclusion criteria. Nine studies evaluated NIV in post-abdominal surgery, three in thoracic surgery, eight in cardiac surgery, three in thoraco-abdominal surgery, four in bariatric surgery and two in post solid organ transplantation used both for prophylactic and therapeutic purposes. NIV improved arterial blood gases in 15 of the 22 prophylactic and in 4 of the 7 therapeutic studies, respectively. NIV reduced the intubation rate in 11 of the 29 studies and improved outcome in only 1.

CONCLUSIONS

Despite these limited data and the necessity of new randomized trials, NIV could be considered as a prophylactic and therapeutic tool to improve gas exchange in postoperative patients.

Influence of upper body position on middle cerebral artery blood velocity during continuous positive airway pressure breathing

Continuous positive airway pressure (CPAP) is a treatment modality for pulmonary oxygenation difficulties. CPAP impairs venous return to the heart and, in turn, affects cerebral blood flow (CBF) and augments cerebral blood volume (CBV). We considered that during CPAP, elevation of the upper body would prevent a rise in CBV, while orthostasis would challenge CBF. To determine the body position least affecting indices of CBF and CBV, the middle cerebral artery mean blood velocity (MCA V(mean)) and the near-infrared spectroscopy determined frontal cerebral hemoglobin content (cHbT) were evaluated in 11 healthy subjects during CPAP at different body positions (15 degrees head-down tilt, supine, 15 degrees, 30 degrees and 45 degrees upper body elevation). In the supine position, 10 cmH(2)O of CPAP reduced MCA V(mean) by 9 +/- 3% and increased cHbT by 4 +/- 2 micromol/L (mean +/- SEM); (P < 0.05). In the head-down position, CPAP increased cHbT to 13 +/- 2 micromol/L but left MCA V(mean) unchanged. Upper body elevation by 15 degrees attenuated the CPAP associated reduction in MCA V(mean) (-7 +/- 2%), while cHbT returned to baseline (1 +/- 2 micromol/L). With larger elevation of the upper body MCA V(mean) decreased progressively to -17 +/- 3%, while cHbT remained unchanged from baseline. These results suggest that upper body elevation by approximately 15 degrees during 10 cmH(2)O CPAP prevents an increase in cerebral blood volume with minimal effect on cerebral blood flow.

Prophylactic use of noninvasive ventilation in patients undergoing lung resectional surgery

QUESTION OF THE STUDY

We studied whether prophylactic use of noninvasive pressure support ventilation (NIPSV) administered pre- and postoperatively may reduce the postoperative pulmonary function impairment.

PATIENTS AND METHODS

Prospective randomized clinical trial. Thirty-nine patients with a preoperative FEV(1) <70% of the predicted value scheduled for elective lobectomy related to lung cancer were enrolled. Seven patients were excluded after enrollment. Patients were required to follow standard treatment without (control group, n=18) or with NIPSV (study group, n=14) during 7 days at home before surgery, and during 3 days postoperatively. Primary outcome variable was the changes on arterial blood gases on room air.

RESULTS

Two hours after surgery, PaO(2), FVC and FEV(1) values were significantly better in the NIPSV group. On day 1, 2 and 3, PaO(2) was significantly improved in the NIPSV group. Also on day 1, FVC and FEV(1) improved significantly in the NIPSV group. The hospital stay was significantly longer in the control group than in the study group (p=0.04). The incidence of major atelectasis was 14.2% in the NIPSV group and 38.9% in the no-NIPSV group (p=0.15). ANSWER TO THE QUESTION: Prophylactic use of NIPSV in a pre- and postoperative manner significantly reduces pulmonary dysfunction after lung resection. As a result, recovery of preoperative respiratory function is accelerated.

Pulmonary Outcomes of Off-Pump vs On-Pump Coronary Artery Bypass Surgery in a Randomized Trial

STUDY OBJECTIVES

Comparison of pulmonary outcomes after off-pump coronary artery bypass (OPCAB) vs on-pump coronary artery grafting with cardiopulmonary bypass (CABG/CPB).

STUDY DESIGN

We examined preoperative and postoperative respiratory compliance, fluid balance, hemodynamics, arterial blood gases, chest radiographs, spirometry, pulmonary complications, and time to extubation in a prospective trial of 200 patients randomized to OPCAB vs CABG/CPB performed by one surgeon.

RESULTS

One CABG/CPB patient and two OPCAB patients required mitral valve repair or replacement and were withdrawn. After three crossovers from CABG/CBP to OPCAB and one crossover from OPCAB to CABG, 97 CABG/CPB patients and 100 OPCAB patients remained. There were no significant preoperative demographic differences between groups. Postoperative compliance was reduced more after OPCAB than after CABG/CPB (- 15.4 +/- 10.7 mL/cm H(2)O vs - 11.2 +/- 10.1 mL/cm H(2)O [mean +/- SD]; p = 0.007), associated with rotation of the heart into the right chest to perform posterolateral bypasses (p < 0.001) and the concomitant increased fluid requirements necessary to maintain hemodynamic stability during rotation of the heart. In addition to higher intraoperative fluid intake (4,541 +/- 1,311 mL vs 3,585 +/- 1,033 mL, p < 0.0001), OPCAB patients had higher intraoperative fluid balance (3,903 +/- 1,315 mL vs 1,772 +/- 1,373 mL, p < 0.0001), and higher postoperative pulmonary arterial diastolic pressure (15.0 +/- 5.5 mm Hg vs 11.8 +/- 5.2 mm Hg, p < 0.0001) and central venous pressure (10.4 +/- 4.5 mm Hg vs 8.4 +/- 4.7 mm Hg, p < 0.0001). Despite lower compliance, immediate postoperative Pao(2) on fraction of inspired oxygen of 1.0 (275 +/- 97 torr vs 221 +/- 92 torr, p = 0.001) was higher after OPCAB and extubation was earlier (p = 0.001). Postoperative chest radiographs, spirometry, mortality, reintubation, or readmission for pulmonary complications were not different between groups.

CONCLUSIONS

Compared to CABG/CPB, OPCAB was associated with a greater reduction in postoperative respiratory compliance associated with increased fluid administration and rotation of the heart into the right chest to perform posterolateral grafts. OPCAB yielded better gas exchange and earlier extubation but no difference in chest radiographs, spirometry, or rates of death, pneumonia, pleural effusion, or pulmonary edema.

Continuous Positive Airway Pressure Versus Noninvasive Pressure Support Ventilation to Treat Atelectasis After Cardiac Surgery

Atelectasis is common after cardiac surgery and may result in impaired gas exchange. Continuous positive airway pressure (CPAP) is often used to prevent or treat postoperative atelectasis. We hypothesized that noninvasive pressure support ventilation (NIPSV) by increasing tidal volume could improve the evolution of atelectasis more than CPAP. One-hundred-fifty patients admitted to our surgical intensive care unit (SICU) with a Radiological Atelectasis Score >or=2 after cardiac surgery were randomly assigned to receive either CPAP or NIPSV four times a day for 30 min. Positive end-expiratory pressure was set at 5 cm H(2)O in both groups. In the NIPSV group, pressure support was set to provide a tidal volume of 8-10 mL/kg. At SICU discharge, we observed an improvement of the Radiological Atelectasis Score in 60% of the patients with NIPSV versus 40% of those receiving CPAP (P = 0.02). There was no difference in oxygenation (Pao(2)/fraction of inspired oxygen at SICU discharge: 280 +/- 38 in the CPAP group versus 301 +/- 40 in the NIPSV group), pulmonary function tests, or length of stay. Minor complications, such as gastric distensions, were similar in the two groups. NIPSV was superior to CPAP regarding the improvement of atelectasis based on radiological score but did not confer any additional clinical benefit, raising the question of its usefulness for altering outcome.

Prophylactic respiratory physiotherapy after cardiac surgery: systematic review

OBJECTIVE

To assess whether respiratory physiotherapy prevents pulmonary complications after cardiac surgery.

DATA SOURCES

Searches through Medline, Embase, Cinahl, the Cochrane library, and bibliographies, for randomised trials comparing any type of prophylactic respiratory physiotherapy with another type or no intervention after cardiac surgery, with a follow up of at least two days, and reporting on respiratory outcomes.

REVIEW METHODS

Investigators assessed trial validity independently. Information on study design, population, interventions, and end points was abstracted by one investigator and checked by the others.

RESULTS

18 trials (1457 patients) were identified. Most were of low quality. They tested physical therapy (13 trials), incentive spirometry (eight), continuous positive airway pressure (five), and intermittent positive pressure breathing (three). The maximum follow up was six days. Four trials only had a no intervention control; none showed any significant benefit of physiotherapy. Across all trials and interventions, average values postoperatively were: incidence of atelectasis, 15-98%; incidence of pneumonia, 0-20%; partial pressure of arterial oxygen per inspired oxygen fraction, 212-329 mm Hg; vital capacity, 37-72% of preoperative values; and forced expiratory volume in one second, 34-72%. No intervention showed superiority for any end point. For the most labour intensive intervention, continuous positive airway pressure, the average cost of labour for each patient day was 27 euro (pound 19; 32 dollars).

CONCLUSIONS

The usefulness of respiratory physiotherapy for the prevention of pulmonary complications after cardiac surgery remains unproved. Large randomised trials are needed with no intervention controls, clinically relevant end points, and reasonable follow up periods.

Nasal CPAP therapy: effects of different CPAP levels on pressure transmission into the trachea and pulmonary oxygen transfer

BACKGROUND

Nasal continuous positive airway pressure (nCPAP) is considered useful for prophylaxis and treatment of respiratory complications following major thoracic surgery. It is unknown, however, which CPAP levels are required to avoid alveolar derecruitment and to consistently improve pulmonary oxygen transfer in patients following thoracotomy. We therefore studied the effects of different nCPAP levels on pressure transmission into the trachea as well as on pulmonary oxygen transfer.

METHODS

In 10 consecutive patients after cardiac or thoracic vascular surgery, following extubation in the ICU, nCPAP was generated by means of a high-flow gas source and applied randomly at levels of 5 or 10 cm H2O. Airway pressure was recorded continuously in the nasal mask and the trachea. The PaO2/FiO2ratio was calculated from the tracheal oxygen concentration, and PaO2 was determined while breathing at an ambient and elevated airway pressure. Haemodynamic variables (heart rate, arterial blood pressure, central venous pressure) were also recorded.

RESULTS

Mean pressures in the nasal mask were 5.4+/-0.1 and 9.7+/-0.3 cm H2O. Corresponding tracheal pressures were 2.8+/-1.0 vs. 7.2+/-1.1 cm H2O (P=0.007). With higher mask pressure, the fraction of pressure transferred from the nasal mask into the trachea was larger (0.75+/-0.03 vs. 0.52+/-0.05; P=0.04), and tracheal pressures remained positive during the entire respiratory cycle in all patients. In contrast, with 5.4 cm H20, negative pressure changes during inspiration occurred in five out of 10 patients. The PaO2/FiO2 ratio increased from 183+/-53 (ambient pressure) to 199+/-74 (nCPAP 5.4 cm H2O; P=0.25) and to 333+/-54 (nCPAP 9.7 cm H2O; P=0.003). Nasal CPAP did not alter hemodynamics.

CONCLUSION

Nasal CPAP is an effective non-invasive means of increasing tracheal and thus intrathoracic pressure without adverse hemodynamic effects. Only mask pressures of 9-10 cm H2O were sufficient to consistently improve pulmonary oxygen transfer in patients following thoracotomy.

The physiotherapy management of patients undergoing coronary artery surgery: A questionnaire survey

The current physiotherapy management of patients undergoing coronary artery surgery in 22 public and 13 private hospitals across Australia and New Zealand was examined using a questionnaire survey. Respondents were asked to identify assessment and treatment techniques used in the pre- and post-operative management. An 83 per cent response from physiotherapists was obtained. Ninety-four per cent of respondents reported that pre-operative assessment was performed routinely. Eighty-nine per cent of respondents indicated that all patients were treated routinely by physiotherapists in the post-extubation period. Positioning and deep breathing exercises were the most commonly used techniques for patients post-extubation. Factors determining treatment choice and the impact of research on current physiotherapy practice are discussed.

The use of positive pressure devices by physiotherapists

The aim of this paper is to review the indications for use by physiotherapists, such as physiological rationale and the comparative efficacy of intermittent positive pressure breathing (IPPB) and continuous positive airway pressure (CPAP). A brief discussion of nasal intermittent positive airway pressure is also included. The use of IPPB for post operative prophylaxis has not been supported in the literature. In patients with low lung volumes resulting from neuromuscular disease or spinal injury, IPPB may be useful in the acute phase to improve tidal volume and cough effectiveness. The physiological benefits of CPAP to improve lung volumes are well documented in the literature. Physiotherapists use CPAP as an intermittent application in patients with low lung volumes following surgery. It is predominantly used as a second line intervention in the presence of refractory atelectasis and poor gas exchange. It may also be indicated in other patient groups with similar physiological problems. Nasal intermittent positive airway pressure combines the beneficial effects of intermittent positive pressure breathing and continuous positive airway pressure. There have been many studies evaluating its effectiveness. These have been supportive for patients with neuromuscular disease and sleep disordered breathing, but more research is needed in patients with acute respiratory failure.

Pulmonary complications after coronary revascularization

Pulmonary complications are common after coronary artery bypass grafting. Identifying those individuals with increased risk of respiratory complications allows for appropriate preoperative intervention. The most commonly seen pulmonary complications include pleural effusion, hemothorax, atelectasis, pulmonary edema, diaphragmatic dysfunction, and pneumonia. Clinical features and appropriate management of these common problems are discussed.

Assisted pressure control ventilation via a mini-tracheostomy tube for postoperative respiratory management of lung cancer patients

Assisted pressure control ventilation (PCV) via a min-tracheostomy tube (MTT) was conducted to improve gas exchange and reduce the work of breathing of lung cancer patients after surgery. Thirty-two patients with lung cancer underwent lobectomy and were managed postoperatively by assisted PCV via an MTT. On the basis of a simulation study using a lung model for clinical use, we set the inspiratory pressure to 20 cmH2O and inspiratory time to 1.0 sec to produce a 450-ml supported volume via the MTT per breath. The blood gases and respiratory rate of each patient were measured under three sets of conditions: PCV via an MTT transtracheal oxygenation (TTO) via an MTT and a Venturi face mask with the same FiO2. After PCV via an MTT overnight, the blood gases in the room air were measured 2.5 h after withdrawing PCV. In order to determine the effect of PCV via an MTT on gas exchange after PCV withdrawal, 32 other age and sex-matched lung cancer patients, who had undergone lobectomy and oxygenation via a face mask alone after surgery, were used as historical controls. The simulation study showed that the ventilated volume provided by assisted PCV via an MTT was about half that provided via a conventional endotracheal tube, even in the presence of air leakage. The clinical application showed that the ventilated volume obtained with the PCV via an MTT was significantly higher than that with spontaneous breathing (P<0.001). PCV via an MTT increased the PaO2 and reduced both the PaCO2 and respiratory rate significantly in comparison with TTO via an MTT and a face mask (P<0.001). After PCV withdrawal the morning after surgery, the PaO2 of the PCV group was significantly higher than that of the historical controls (P<0.001). No postoperative pulmonary complications were observed in either the PCV or the control groups, however. In addition, no complications or morbidity were seen related to either MTT insertion or PCV via an MTT. Assisted PVC via an MTT increased the tidal volume, improved the gas exchange, reduced the respiratory rate by providing adequate ventilatory support and increased the PaO2, even after withdrawal following lung surgery. Even though we did not observe any benefit of clinical outcome with PCV via an MTT in the present study, this procedure appears to be a potentially useful respiratory management modality for patients with high risk of postoperative pulmonary complications.

Effect of bi-level positive airway pressure (BiPAP) nasal ventilation on the postoperative pulmonary restrictive syndrome in obese patients undergoing gastroplasty

STUDY OBJECTIVE

Upper abdominal surgery results in a postoperative restrictive pulmonary syndrome. Bi-level positive airway pressure (BiPAP System; Respironics Inc; Murrysville, Pa), which combines pressure support ventilation and positive end-expiratory pressure via a nasal mask, could allow alveolar recruitment during inspiration and prevent expiratory alveolar collapse, and therefore limit the postoperative pulmonary restrictive syndrome. This study investigated the effect of BiPAP on postoperative pulmonary function in obese patients after gastroplasty.

DESIGN

Prospective controlled randomized study.

SETTING

GI surgical ward in a university hospital.

PATIENTS

Thirty-three morbidly obese patients scheduled for gastroplasty were studied.

INTERVENTION

The patients were assigned to one of three techniques of ventilatory support during the first 24 h postoperatively: O2 via a face mask, BiPAP System 8/4, with inspiratory and expiratory positive airway pressure set at 8 and 4 cm H2O, respectively, or BiPAP System 12/4 set at 12 and 4 cm H2O. Pulmonary function (FVC, FEV1, and peak expiratory flow rate [PEFR]) were measured the day before surgery, 24 h after surgery, and on days 2 and 3. Oxygen saturation by pulse oximeter (SpO2) was also recorded during room air breathing.

RESULTS

Three patients were excluded. After surgery, FVC, FEV1, PEFR, and SpO2 significantly decreased in the three groups. On day 1, FVC and FEV1 were significantly improved in the group BiPAP System 12/4, as compared with no BiPAP; SpO2 was also significantly improved. After removal of BiPAP System 12/4, these benefits were maintained, allowing faster recovery of pulmonary function. No significant effects were observed on PEFR. BiPAP System 8/4 had no significant effect on the postoperative pulmonary restrictive syndrome.

CONCLUSION

Prophylactic use of BiPAP System 12/4 during the first 24 h postoperatively significantly reduces pulmonary dysfunction after gastroplasty in obese patients and accelerates reestablishment of preoperative pulmonary function.

Effects of continuous (CPAP) and bi-level positive airway pressure (BiPAP) on extravascular lung water after extubation of the trachea in patients following coronary artery bypass grafting

OBJECTIVE

To evaluate the effects of continuous positive airway pressure (CPAP) and bi-level positive airway pressure (Bi-PAP) on extravascular lung water during weaning from mechanical ventilation in patients following coronary artery bypass grafting.

DESIGN

Prospective, randomized clinical study.

SETTING

Intensive care unit at a university hospital.

PATIENTS

Seventy-five patients following coronary artery bypass grafting.

INTERVENTIONS

After extubation of the trachea, patients were treated for 30 min with CPAP via face mask (n = 25), with nasal BiPAP (n = 25), or with oxygen administration via nasal cannula combined with routine chest physiotherapy (RCP) for 10 min (n = 25).

MEASUREMENTS AND RESULTS

Extravascular lung water (EVLW), pulmonary blood volume index (PBVI) and cardiac index (CI) were obtained during mechanical ventilation (T1), T-piece breathing (T2), interventions (T3), spontaneous breathing 60 min (T4) and 90 min (T5) after extubation of the trachea using a combined dye-thermal dilution method. Changing from mechanical ventilation to T-piece breathing did not show any significant differences in EVLW between the three groups, but a significant increase in PBVI from 155 +/- 5 ml/m2 to 170 +/- 4 ml/m2 could be observed in all groups (p < 0.05). After extubation of the trachea and treatment with BiPAP. PBVI decreased significantly to 134 +/- 6 ml/m2 (p < 0.05). After treatment with CPAP or BiPAP, EVLW did not change significantly in these groups (5.5 +/- 0.3 ml/kg vs 5.0 +/- 0.4 ml/kg and 5.1 +/- 0.4 ml/kg vs 5.7 +/- 0.4 ml/kg). In the RCP-treated group, however, EVLW increased significantly from 5.8 +/- 0.3 ml/kg to 7.1 +/- 0.4 ml/kg (p < 0.05). Sixty and 90 min after extubation, EVLW stayed at a significantly higher level in the RCP-treated group (7.5 +/- 0.5 ml/kg and 7.4 +/- 0.5 ml/kg) than in the CPAP-(5.6 +/- 0.3 ml/kg and 5.9 +/- 0.4 ml/kg) or BiPAP-treated groups (5.2 +/- 0.4 ml/kg and 5.2 +/- 0.4 ml/kg). No significant differences in CI could be observed within the three groups during the time period from mechanical ventilation to 90 min after extubation of the trachea.

CONCLUSIONS

Mask CPAP and nasal BiPAP after extubation of the trachea prevent the increase in extravascular lung water during weaning from mechanical ventilation. This effect is seen for at least 1 h after the discontinuation of CPAP or BiPAP treatment. Further studies have to evaluate the clinical relevance of this phenomenon.

Noninvasive positive-pressure ventilation in patients with acute respiratory failure

This article provides a systematic review of the literature on the application of noninvasive ventilation in various forms of hypercapnic and hypoxemic respiratory failures. A description of the underlying pathophysiology is followed by a review of physiologic data explaining the mechanisms of action of noninvasive ventilation. A critical review of clinical studies is presented with specific suggestions. The methodology of correctly implementing and monitoring noninvasive ventilation in patients with acute respiratory failure, critical to success, is detailed.