Surfactant replacement in neonatal and adult respiratory distress syndrome

Animal experiments and clinical trials have shown that the neonatal respiratory distress syndrome (RDS) can be treated effectively by surfactant replacement via the airways. This treatment facilitates the resorption of fetal pulmonary fluid, promotes uniform air expansion of the lungs, enhances gas exchange, reduces the protein leak across the alveolar epithelium, and prevents the development of bronchiolar epithelial lesions during artificial ventilation. Data from recent animal experiments indicate that surfactant replacement prevents epithelial lung lesions also during high frequency ventilation. Surfactant replacement restores blood gases to normal in adult experimental animals with severe respiratory insufficiency induced by repeated lung lavage, suggesting that this type of treatment might be effective in clinical adult RDS.     

Noninvasive Positive Pressure Ventilation in burns

Objective: Acute respiratory failure is a common complication of the severely burn-injured patient. Endotracheal intubation and mechanical ventilation is associated with a high rate of complications. Noninvasive Positive Pressure Ventilation (NIPPV) has been shown to be as effective as conventional ventilation in improving gas exchange and is associated with fewer complications with patients in acute hypercapnic and hypoxaemic respiratory failure. We report our experience with NIPPV in 30 burn patients.

Method: The records of all burn patients from 1998 to 2000, where NIPPV was used as part of their management at the St. Andrew’s Centre for Plastic Surgery and Burns, were reviewed.

Results: Mean age was 47.56 years (range 12–81). Nine patients were female. Mean burn size was 24.4% total body surface area (TBSA) (range 3–54). Inhalation injury was confirmed in eight cases. A positive diagnosis of pneumonia was made in 29 patients. The mean PaO₂/FiO₂ ratio prior to institution of NIPPV was 28.98 Kpa (range 8.75–52). Intermittent Positive Pressure Breathing (IPPB) was the most common ventilatory mode employed (25 patients) and the face mask was the most used interface (18 cases). Twenty-two patients (74%) avoided endotracheal intubation and their respiratory function continued to improve after NIPPV was discontinued. One patient (3%) died and seven patients (23%) were reintubated. Three out of the seven were electively reintubated for burns surgery.

Conclusion: In burn-injured patients with acute respiratory failure, NIPPV appears to be effective in supporting respiratory function such that endotracheal intubation can be avoided in most cases.     

Inhaled nitric oxide for adult respiratory distress syndrome after pulmonary resection

Background. The adult respiratory distress syndrome (ARDS) developing after pulmonary resection is usually a lethal complication. The etiology of this serious complication remains unknown despite many theories. Intubation, aspiration bronchoscopy, antibiotics, and diuresis have been the mainstays of treatment. Mortality rates from ARDS after pneumonectomy have been reported as high as 90% to 100%.

Methods. In 1991, nitric oxide became clinically available. We instituted an aggressive program to treat patients with ARDS after pulmonary resection. Patients were intubated and treated with standard supportive measures plus inhaled nitric oxide at 10 to 20 parts/million. While being ventilated, all patients had postural changes to improve ventilation/perfusion matching and management of secretions. Systemic steroids were given to half of the patients.

Results. Ten consecutive patients after pulmonary resection with severe ARDS (ARDS score = 3.1 ± 0.04) were treated. The mean ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen at initiation of treatment was 95 ± 13 mm Hg (mean ± SEM) and improved immediately to 128 ± 24 mm Hg, a 31% ± 8% improvement (p < 0.05). The ratio improved steadily over the ensuing 96 hours. Chest x-rays improved in all patients and normalized in 8. No adverse reactions to nitric oxide were observed.

Conclusions. We recommend the following treatment regimen for this lethal complication: intubation at the first radiographic sign of ARDS; immediate institution of inhaled nitric oxide (10 to 20 parts per million); aspiration bronchoscopy and postural changes to improve management of secretions and ventilation/perfusion matching; diuresis and antibiotics; and consideration of the addition of intravenous steroid therapy.     

Pulmonary Contusion: An Update on Recent Advances in Clinical Management

Pulmonary contusion is a common finding after blunt chest trauma. The physiologic consequences of alveolar hemorrhage and pulmonary parenchymal destruction typically manifest themselves within hours of injury and usually resolve within approximately 7 days. Clinical symptoms, including respiratory distress with hypoxemia and hypercarbia, peak at about 72 h after injury. The timely diagnosis of pulmonary contusion requires a high degree of clinical suspicion when a patient presents with trauma caused by an appropriate mechanism of injury. The clinical diagnosis of acute parenchymal lung injury is usually confirmed by thoracic computed tomography, which is both highly sensitive in identifying pulmonary contusion and highly predictive of the need for subsequent mechanical ventilation. Management of pulmonary contusion is primarily supportive. Associated complications such as pneumonia, acute respiratory distress syndrome, and long-term pulmonary disability, however, are frequent sequelae of these injuries.     

Inguinal herniorrhaphy in young infants: Perianesthetic complications and associated preanesthetic risk factors

Study Objectives: (1) To prospectively observe and tabulate all preaanesthetic complications in young infants undergoing herniorrhaphy with general anesthesia and (2) to identify all major postnatal complications and determine which, if any, might be significant risk factors for perianesthetic complications.

Design: Prospective case control study.

Setting: Columbus, Ohio, Children's Hospital, a teaching and tertiary referral center.

Patients: One hundred two consecutive infants 60 weeks postconceptual age (PCA) or younger undergoing herniorrhaphy with general anesthesia.

Interventions: None

Measurements and Main Results: All perionesthetic complications occurring during anesthesia, in the postanesthesia care unit (PACU), during the remaining hospital stay, and within 30 days of anesthesia were recorded, and a detailed postnatal history was compiled. Fifty-five percent of 60 preterm infants [37 weeks gestational age (GA) or younger] and 50% of 42 term infants (older than 37 weeks GA) experienced at least one perianesthetic complication. Following discharge from the PACU, in-house complications were confined to the preterm group. Significant risk factors included a history of apnea, bradycardia, and ventilatory support for at least 24 hours after birth, mainly for respiratory distress syndrome.

Conclusions: In a teaching hospital, prospectively observed preaanesthetic complications can occur in more than 50% of infants 60 weeks PCA or younger undergoing herniorrhaphy with inhalation anesthesia. Infants younger than 49 weeks PCA with a significant preanesthetic risk factor should be monitored overnight for apnea and bradycardia.     

肺表面活性物质治疗新生儿呼吸窘迫综合征疗效观察

目的 观察肺PS治疗新生儿呼吸窘迫综合征的疗效.方法 对笔者所在医院新生儿特护病房收住的22例新生儿呼吸窘迫综合征患儿使用PS,观察其治疗后的临床反应、血气变化及胸片肺透亮度的变化情况.结果应用PS后,可发现患儿皮肤迅速转红,血氧饱和度上升,不进行机械通气的患儿呻吟、气促情况缓解,呼吸困难、三凹征、紫绀症状减轻或消失 辅助机械通气的患儿用药后30min均下调呼吸机参数,生命体征监测平稳,6～12h复查胸片,肺透亮度明显好转.用药前与用药后2h查血气,pH、PCO2、PO2均有显著差异.结论 使用外源性PS替代疗法治疗新生儿呼吸窘迫综合征,减少了NRDS的发病率及疾病的严重程度,降低了呼吸机使用条件,降低了病死率,疗效较好.     

Can Postoperative Pulmonary Conditions be Improved by Treatment with the Bartlett-Edwards Incentive Spirometer after Upper Abdominal Surgery?

During the immediate postoperative course after upper abdominal surgery, pulmonary complications often occur, caused, inter alia, by reduced regional ventilation and by atelectases as a result of: (1) narrowing of the small peripheral bronchi, and (2) impaired respiratory function. Based on these pathophysiological mechanisms, an instrument (Bartlett-Edwards Incentive Spirometer) has been devised, which aims at giving the patient an opportunity of sustained maximal inspiration under standardized and controlled conditions. The use of this instrument has been followed by reports of a considerable reduction in postoperative pulmonary complications. In a controlled clinical investigation of the pre- and postoperative condition of the lungs, we were unable to show any beneficial effect of the instrument. In general, we have a low frequency of severe postoperative pulmonary complications, as compared with the results reported in the literature. We ascribe this to our very effective pre- and postoperative respiratory therapy.     

肝移植术后的肺部并发症

肝移植术后肺部并发症的发生率非常高,包括肺不张、胸腔积液、肺水肿、肺部感染和急性呼吸衰竭等,严重影响病人的预后.引起肝移植术后肺部并发症的因素很多,主要包括手术操作、感染、循环容量超负荷、输血相关的急性肺损伤、缺血/再灌注、呼吸机相关性肺损伤、肝肺综合征和门肺高压症等因素,以此为依据,现提出了具体的防治措施,包括完善的术前准备、防止容量超负荷、合理输血和血制品,调节凝血功能,注意预防输血相关的急性肺损伤(transtnsion related acutte lung injury,TRALL)、合理应用抑肽酶、减轻缺血/再灌注损伤(ischemia-reperfusion injury,L/R)和全身炎症反应、防治肺动脉高压、合理的呼吸机通气管理等,希望有助于肝移植术后肺部并发症的防治,促进肝移植病人预后.     

�������ܲ�ȫ������ǰ��ع�������

??Preoperative physiologic assessment for patients with respiratory insufficiency SHEN Ce. The Sixth People Hospital of Shanghai Jiao Tong University, Shanghai 200233, China
Abstract The physiologic assessment of patients with respiratory insufficiency should be considered for surgery in order to reduce the postoperative pulmonary complications. The examinations help preoperative risk assessment of the patient. They are the 6min walk, chest CT??pulmonary function test, ventilation and perfusion lung scanning??Doppler venous flow detection and cardiopulmonary exercise testing. The best method for preoperative risk assessment is that pulmonologist, cardiologist, anaesthetist and surgeon discuss the surgery risk and prognosis together.     

肥胖患者围术期通气策略的研究进展

肥胖患者在手术人群中所占的比例逐年上升.肥胖不仅影响了患者的生理功能,也给麻醉和手术带来不少难题.现就此讨论肥胖患者围手术期的呼吸管理,包括术前的呼吸治疗、术中的机械通气策略及术后的呼吸支持等问题.对肥胖患者围术期呼吸生理改变的了解,详尽的、个体化的通气设置和术中术后完善的通气管理有助于减少肥胖患者呼吸系统并发症的发生.     

The role of dead space ventilation in predicting outcome of successful weaning from mechanical ventilation.

BACKGROUND: The exact mechanism by which tracheostomy results in clinical improvement in respiratory function and liberation from mechanical ventilation remains unknown. Physiologic dead space, which includes both normal and abnormal components of non-gas exchange tidal volume, is a clinical measure of the efficiency of ventilation. Theoretically, tracheostomy should reduce dead space ventilation and improve pulmonary mechanics, thereby facilitating weaning from mechanical ventilation. METHODS: This study compares arterial blood gases (ABG), pulmonary mechanics, including minute ventilation (VE) and dead space ventilation (Vd/Vt) within 24 hours before and after tracheostomy in 45 patients admitted to a surgical intensive care unit. RESULTS: There was no difference noted in patients' ABG or VE. Pre- and posttracheostomy change in Vd/Vt was negligible (50.7 and 10 vs. 51.9 and 11; p = NS). On subgroup analysis, those patients that were weaned from mechanical ventilation with 72 hours of tracheostomy (T3) were compared with those patients weaned from mechanical ventilation 5 days or more after tracheostomy (T+5). Again, no difference was found in pulmonary mechanics or Vd/Vt pre- and posttracheostomy. CONCLUSION: There is minimal improvement in pulmonary mechanics after tracheostomy. The change in physiologic dead space posttracheostomy does not predict the outcome of weaning from mechanical ventilation. Tracheostomy does allow better pulmonary toilet, and easier initiation and removal of mechanical ventilation and control of the upper airway.     

Effect of hemofiltrated whole blood pump priming on hemodynamics and respiratory function after the arterial switch operation in neonates

Background. Primed blood might have some deleterious effects on neonates during cardiopulmonary bypass (CPB) due to unbalanced electrolytes and inflammatory mediators. We hemofiltrated pump-primed blood before CPB to reduce inflammatory mediators and to adjust pH and the concentrations of electrolytes. The current study investigated the effects of hemofiltrated whole blood priming on hemodynamics and respiratory function after CPB in neonates.

Methods. Patients who underwent the arterial switch operation in the neonatal period for transposition of the great arteries with intact ventricular septum were chosen for this study. Seventeen patients underwent CPB with hemofiltrated blood priming (group HF) and 23 patients underwent CPB with nonhemofiltrated blood priming (group N). The concentrations of electrolytes and bradykinin and high molecular weight kininogen of the primed blood before and after hemofiltration were measured. At 4 hours after completion of CPB, the left ventricular percent fractional shortening, and the relation between the mean velocity of shortening and the end-systolic wall stress (stress velocity index), were measured by echocardiogram in 7 patients in group HF and 6 patients in group N. Alveolar − arterial oxygen tension difference (AaDO₂) and respiratory index (AaDO₂ divided by arterial oxygen tension) were measured at several points for 48 hours after CPB in all patients.

Results. Hemofiltration of the primed blood maintained electrolytes within a physiologic level and significantly reduced the concentrations of bradykinin (5,649 ± 1,353 pg/mL versus 510 ± 35 pg/mL, p < 0.05) and high molecular weight kininogen (52.7% ± 3.2% versus 40.1% ± 3.0% of normal plasma value, p < 0.05). The percent of fractional shortening at 4 hours after completion of CPB was significantly higher in group HF (n = 7) than in group N (n = 6) (22.0% ± 0.7% versus 16.0% ± 0.4%, p < 0.01). There was also a trend toward better stress velocity index in group HF than in group N (0.81 ± 0.81 versus −2.17 ± 0.45, p = 0.09). AaDO₂ and respiratory index were significantly lower in group HF than in group N for 48 hours after CPB, respectively (p < 0.05).

Conclusions. Hemofiltrated fresh whole blood used for CPB priming attenuated cardiac impairment at early reperfusion periods and reduced pulmonary dysfunction in neonates with transposition of the great arteries with intact ventricular septum. This therapeutic strategy may have an advantage in preventing lung and heart dysfunction in pediatric patients who need CPB priming with blood.     

Total Arteriovenous CO2 Removal: Simplifying Extracorporeal Support for Respiratory Failure

Background. To reduce the complexity, complications, and cost of conventional extracorporeal membrane oxygenation, we have developed a technique of simplified arteriovenous extracorporeal CO₂ removal (AVCO₂R) with a low-resistance membrane gas exchanger for total CO₂ removal to provide lung rest in the setting of severe respiratory failure.

Methods. We initially used AVCO₂R in healthy animals to quantify the gas exchange capabilities of the system and establish ventilator management protocols for the subsequent studies of AVCO₂R in a large animal model of respiratory failure secondary to a severe smoke inhalation injury.

Results. In healthy sheep the maximum spontaneous arteriovenous flow ranged from 1,350 to 1,500 mL/min, whereas CO₂ removal plateaued at a blood flow of approximately 1,000 mL/min in which 112 ± 3 mL/min CO₂ was removed, allowing an 84% reduction in the minute ventilation of from 6.9 ± 0.8 L/min to 1.1 ± 0.4 L/min (p < 0.01) without triggering hypercapnia. A subsequent reduction in extracorporeal flow at a reduced minute volume led to the development of hypercapnia only if it decreased to less than 500 mL/min. We also applied AVCO₂R in mechanically ventilated sheep with a severe smoke inhalation injury and removed 95% (111 ± 4 mL/min) of the total CO₂ production. This allowed the minute ventilation to be reduced by 95% and the peak inspiratory pressures by 52% (both p < 0.05) over 6 hours and produced no adverse hemodynamic effects. The partial pressure of arterial oxygen was maintained above 100 mm Hg at a maximally reduced minute volume. The mean AVCO₂R flow was 1,213 ± 29 mL/min, averaging 27% ± 1% of the cardiac output.

Conclusions. We conclude that AVCO₂R in a simple arteriovenous shunt is a less complicated technique than extracorporeal membrane oxygenation and is capable of total CO₂ removal that allows a significant reduction in the minute ventilation and peak airway pressure during severe respiratory failure.     

Reperfusion injury significantly impacts clinical outcome after pulmonary transplantation

Background. Reperfusion injury after pulmonary transplantation can contribute significantly to postoperative pulmonary dysfunction. We hypothesized that posttransplantation reperfusion injury would result in an increase in both in-hospital mortality and morbidity. We also hypothesized that the incidence of reperfusion injury would be dependent upon the cause of recipient lung disease and the interval of donor allograft ischemia.

Methods. We performed a retrospective study of all lung transplant recipients at our institution from June 1990 until June 1998. One hundred patients received 120 organs during this time period. We compared two groups of patients in this study: those experiencing a significant reperfusion injury (22%) and those who did not (78%).

Results. In-hospital mortality was significantly greater in patients experiencing reperfusion injury (40.9% versus 11.7%, p < 0.02). Posttransplantation reperfusion injury also resulted in prolonged ventilation (393.5 versus 56.8 hours, p < 0.001) and an increased length of stay in both the intensive care unit (22.2 versus 10.5 days, p < 0.01) and in the hospital (48.8 versus 25.6 days, p < 0.03). The incidence of reperfusion injury could not be attributed to length of donor organ ischemia (221.5 versus 252.9 minutes, p < 0.20). The clinical impact of reperfusion injury was significantly greater in patients undergoing transplantation for preexisting pulmonary hypertension (6/14) than those with chronic obstructive pulmonary disease or emphysema alone (6/54) (42.9% versus 11.1%, p < 0.012).

Conclusions. Clinically significant pulmonary reperfusion injury increased in-hospital mortality and morbidity resulting in prolonged ventilation, length of stay in the intensive care unit, and cost of hospitalization. The incidence of reperfusion injury was not dependent upon the duration of donor organ ischemia but increased with the presence of preoperative pulmonary hypertension. These findings suggest that recipient pathophysiology and donor allograft quality may play important roles in determining the incidence of reperfusion injury.     

Postpneumonectomy Syndrome With an Ipsilateral Aortic Arch After Left Pneumonectomy

Background. Previous reports have described bronchial obstruction after left pneumonectomy (so-called postpneumonectomy syndrome) in the presence of a right aortic arch with the bronchus being compressed between the ascending aorta and thoracic spine. This study reports on 4 patients with left postpneumonectomy syndrome in the presence of a normally located left aortic arch and ascending thoracic aorta.

Methods. The case histories of 4 patients with this syndrome were reviewed and several features common to all 4 were noted. In each case, the obstruction was thought to be due to a clockwise rotation of the mediastinum with bronchial compression occurring between the right main pulmonary artery and thoracic spine.

Results. Three patients were treated by repositioning of the mediastinum, and all 3 obtained relief of their dyspnea. In these cases, permanent repositioning was ensured by the insertion of a prosthesis filled with saline solution. The fourth patient was successfully treated by resection of a portion of the adjacent thoracic vertebra.

Conclusions. Postpneumonectomy syndrome can occur after a left pneumonectomy in the absence of a right aortic arch. We suggest that mediastinal repositioning with a prosthesis filled with saline solution is simple, is safe, and results in complete relief of preoperative symptoms.     

The fat embolism syndrome treated with oxygen, diuretics, sodium restriction and spontaneous ventilation.

The fat embolism syndrome is a self limiting disease with its mortality related to the degree of respiratory failure. Treatment therefore is directed at maintaining satisfactory pulmonary gas exchange throughout the course of the disease. In 28 consecutive patients diagnosed with fat embolism syndrome and severe respiratory failure, therapy consisted of oxygen, diuretics, sodium restriction and a trial of spontaneous ventilation. There was no mortality.     

呼吸功能不全病人术前相关功能评价

对合并肺功能不全病人的术前评估,应对个人的具体情况作出判断,以降低手术的风险。包括：6min步行试验、胸部CT检查、肺通气功能、肺弥散功能、放射性核素肺通气、肺血流灌注显像及运动性心肺功能检查等有助于做出正确的判断。最稳妥的办法是术前心脏、呼吸及麻醉专业的医生共同评价手术风险及预后。     

Comparison of conventional mandatory ventilation and high frequency oscillatory ventilation for treatment of acute lung injury induced by steam inhalation injury

This study compared pathophysical indexes, respiratory mechanics, circulatory parameters and lung injury scores of acute lung injury (ALI) induced by steam inhalation injury in a New Zealand rabbit model with different ventilatory strategies: a control group which consisted of lower tidal volume (VT 6 ml/kg) and high positive end-expiratory pressure (PEEP) (9 cmH₂O); treatment group which was high frequency oscillatory ventilation (HFOV). Eighteen rabbits were anaesthetized, sedated, neuromuscular-blocked and ventilated with above two modes at our animal laboratory of burn center. After induction of acute lung injury by steam inhalation, animals were randomizedly assigned to receive either conventional mechanical ventilation (CMV) or high frequency oscillatory ventilation and were grouped as CMV and HFOV group. As a result, HFOV attenuated the decrease in oxygenation and pulmonary compliance, alleviated lung tissue damage and inflammatory response. Therefore, HFOV may be a preferable option for treatment of acute lung injury induced by steam inhalation injury.     

The impact of the duration of mechanical ventilation on the respiratory outcome in smokers undergoing cardiac surgery

STUDY OBJECTIVE: To determine the impact of the duration of mechanical ventilation on the rate of pulmonary complications in smokers undergoing cardiac surgery. METHODS: Retrospective analysis of 2163 patients who underwent elective cardiac surgery between September 1993 and August 1999. Based on a 3-month preoperative smoking cessation, patients were classified as smokers, ex-smokers and non-smokers. Their postoperative pulmonary complications were compared and related to the duration of mechanical ventilation. RESULTS: Postoperative pulmonary complications were twice as common in smokers (29.5%) as non-smokers (13.6%) and ex-smokers (14.7%). Although smokers required a longer duration of mechanical ventilation, this was not statistically significant. Smokers had a higher rate of increase in postoperative pulmonary complications beyond 6 h of mechanical ventilation (P<0.002). CONCLUSION: Prolonged mechanical ventilation in active smokers undergoing cardiac surgery is associated with a significant increase in the respiratory morbidity. Surgical strategies that allow early extubation may improve the respiratory outcome in smokers.