Use of non-invasive positive pressure ventilation for cardiogenic pulmonary edema in emergency care units

The work reported by L'Her et al. in this issue of La Presse Médicale demonstrates the feasibility of applying simple intensive care techniques in situations frequently encountered in emergency care units. These authors used a face mask for continuous positive pressure ventilation in patients over 70 years of age admitted for respiratory distress related to cardiogenic pulmonary edema. In these elderly patients, the authors noted an improvement in blood gases, respiratory rate and heart rate and did not observe any secondary effect. Acute respiratory failure was cured in 90% of the cases without referral to the intensive care unit. The mechanism of action of continuous positive airway pressure, or spontaneous ventilation with positive expiratory pressure, is different from simple oxygen therapy. Two mechanisms are intimately related. The main effect is ventilatory assistance resulting from a "re-aeration" of the pulmonary parenchyma which increases compliance and reduces work required to overcome elastic retraction forces. Likewise the increased pulmonary volume reduces pulmonary resistance. Positive airway pressure also has an effect on left ventricular function. Indeed, after-load is reduced by the reduction in the large negative intrathoracic pressure swing. Lower energy expenditure required for respiration also greatly reduces total oxygen consumption and improved blood gases favor oxygen supply to the myocardium. The contraindications of continuous positive airway pressure are related to abnormal control of the upper airways and major hemodynamic disorders. Prudence is also required in case of shock due to the risk of major respiratory muscle fatigue. The question could also be raised as to the risk in elderly patients where cardiogenic pulmonary edema is often associated with a certain degree of chronic bronchitis. It is now known that these patients have an intrinsic positive expiratory pressure which considerably increases respiratory work. Symptomatic treatment in this type of disorder is mechanical and continuous positive airway pressure diminishes this work. Cardiogenic pulmonary edema in the elderly is thus an excellent indication for spontaneous ventilation with positive expiratory pressure. Improvement in these simple techniques, their widespread use and a better understanding of their limitations remain important challenges for the future.     

Changes in Plasma Angiotensin Ⅱ and Circadian Rhythm of Blood Pressure in Hypertensive Patients with Sleep Apnea Syndrome Before and After Treatment

Objective To explore the changes in plasma angiotensin Ⅱ (Ang Ⅱ) and circadian rhythm of blood pressure among hypertensive patients with sleep apnea syndrome (SAS) before and after continuous positive airway pressure (CPAP) or surgical treatment.Methods A total of 180 essential hypertension patients were enrolled in our study.The determination of plasma Ang Ⅱ concentration,ambulatory blood pressure (ABP),and polysomnography (PSG) monitoring were performed before and 3 months after CPAP or surgical treatment.Results Patients were classified into three groups by their apnea-hypopnea index (AHI):essential hypertension group (EH group,n=72; AHI<5),essential hypertension with mild SAS group (EH+mild SAS group,n=60,5≤AHI<20),and essential hypertension with moderate and severe SAS group (EH+moder-ate-severe SAS group,n=48,AHI≥20).The concentrations of plasma Ang Ⅱ in the above three groups were 13.42+3.27,16.17+3.82,and 18.73+4.05 ng/mL respectively before treatment,and Ang Ⅱ concentration in EH patients combined with SAS was significantly higher than that in EH group (all P<0.05).After treatment the values in the latter two groups significantly decreased to 14.67+2.56 and 15.03+3.41 ng/mL respectively (P<0.05).The incidence of non-dipper blood pressure curve in EH patients was 31.9%,and those in hypertensive patients with mild SAS and moderate-severe SAS were 51.7% and 58.3%,respectively before treatment.The incidence of non-dipper blood pressure curve in the EH patients with mild SAS was significantly higher than that of patients with EH alone (P<0.05).After CPAP treatment or surgery,the incidence of non-dipper blood pressure curve in the two SAS groups was significantly decreased to 38.3% and 39.6%,respectively (P<0.05).Conclusions Ang Ⅱ might play a role in blood pressure variability in patients with obstructive SAS.CPAP or surgical treatment can improve blood pressure disorder and decrease plasma Ang Ⅱ level in patients with obstructive SAS.     

Nocturnal pulmonary hypertension in an elderly patient with sleep apnea syndrome

We report a case of sleep apnea syndrome (SAS) with nocturnal pulmonary hypertension (NPH) in a 71-year-old man suffering from dyspnea during sleep. Severe snoring at night and daytime sleepiness were noticed before admission by his wife. Nocturnal oxygen desaturation (NOD) was documented with a pulse oximeter and severe sleep apnea syndrome was diagnosed on the basis of results of respiratory inductive plethysmography, an apnea index (AI) > 20, minimum SpO2 56%. NPH was diagnosed by Swan-Ganz catheter. The levels of NPH were severe. Elevation of systolic pulmonary arterial pressure (PAP) above 40 mmHg was observed 137 episodes at night. Both NPH and NOD were improved by 1 L/min of nasal oxygen therapy. A number of episodes of systolic PAP above 40 mmHg with oxygen therapy was 55 episodes. Peak mean PAP was 36 mmHg in room air vs 33 mmHg in oxygen therapy. Minimum SpO2 with oxygen therapy was improved to 69%. Total time of SpO2 < 90% at night was 153 minutes in room air vs 37 minutes in oxygen therapy. In this case, NPH and NOD due to severe SAS were remarkably improved by oxygen therapy.     

Respiratory failure based on pulmonary tuberculosis sequelae and its management

According to the complexity of pathological change of pulmonary tuberculosis sequelae (TB seq), on which respiratory failure based shows the higher incidence of marked degree of hypoxemia and hypercapnia than that based on chronic pulmonary emphysema (CPE). In TB seq, pulmonary artery mean pressure is higher, nocturnal oxyhemoglobin desaturation is much lower than in CPE. Also hypoxemia on exercise is lower, and oxygen inhalation for this hypoxemia is more effective than in CPE. The most effective therapy is continuous oxygen therapy. Home oxygen therapy has improved the prognosis and quality of life (QOL) of patients with respiratory failure based on TB seq. Artificial positive pressure ventilation (TIPPV) with intubation or tracheotomy is carried out for patients with severe hypercapnia and respiratory acidosis. Recently, early application of nasal mask ventilation (NPPV) on patients with TB seq has prohibited acute exacerbation of chronic respiratory failure. And also for patients with severe hypercapnia, NPPV with BIPAP method is effective for their QOL. Comprehensive respiratory rehabilitation is also successfully applied for their management.     

Physiological changes occurring with positive pressure ventilation: Part Two

Although the physiological effects of positive pressure ventilation are numerous, sometimes undesirable and have varying degrees of significance, positive pressure ventilation still plays a major role in the resuscitation and treatment of critically ill patients. Advances in the various methods of delivering positive pressure, especially when incorporating spontaneous breathing, have reduced the severity of complications. Despite serious complications, mechanical ventilation has advantages. When it is instituted for ventilatory and hypoxaemic respiratory failure, the benefits can be viewed in the context of the work of breathing. Spontaneous breathing normally requires 5% of total oxygen delivery to meet its demands. In lung disease, the ratio of oxygen consumption by the respiratory muscles to whole body oxygen consumption can increase to 25-30% (Henning 1986, Pinksy 1990). Mechanical ventilation reduces the energy demand of respiratory muscles and increases the oxygen delivery to other vital organs. When mechanical ventilation improves hypoxaemia and/or hypercarbia, or significantly decreases the work of breathing, it may also normalize associated changes in heart rate (Perel & Pizov 1991 p53). When cardiac output is increased in response to the increased work of breathing and associated stress, the institution of mechanical ventilation may beneficially lower the cardiac output simply due to the decrease in oxygen demand; thus the physiological reduction in cardiac output may not necessarily be regarded as a complication. The effects of raised intrathoracic pressure during mechanical ventilation may be beneficial when used to prevent or reduce pulmonary oedema, though problematic in some other situations. Mechanical ventilation is a life-saving treatment which has many associated complications; nurses have to accept the unavoidable hazards and adapt their nursing care to minimize their effects.     

The obstructive sleep apnoea syndrome--experience of a referral centre

OBJECTIVE: The aims of this study were: (i) to document the presence and severity of obstructive sleep apnoea (OSA) in patients who complained of heavy snoring and other symptoms suggestive of the OSA syndrome; (ii) to examine the correlation between the clinical and polygraphic findings, and (iii) to document the efficacy and compliance of nasal continuous positive airway pressure (CPAP) among these Asian snorers with OSA. METHODS: We analysed our clinical and nocturnal polysomnographic data between January 1986 and December 1995 for physician-referred patients who had complained of snoring and other symptoms suggestive of OSA. RESULTS: A total of 277 diagnostic studies were performed of which 145 (52%) were positive to OSA. For studies performed in the last 2 years (n = 125), 72 of the 125 were positive for OSA. Anthropometric data was not discriminative between the OSA positive snorers and the OSA negative snorers. We found that hypertension and choking were the most significantly related to OSA, conferring a 7 and 4 times relative risk respectively. Nasal CPAP eliminated snoring, apnoeas and oxygen desaturations completely in almost all cases and there were only minor mask-related side effects. CONCLUSION: OSA may not be uncommon among Asian snorers. Of the major traits for OSA risk among our local population, a history of hypertension and reports of nocturnal choking were the most significantly related. We have also shown that nasal CPAP is safe and effective among our local snorers and should be considered a first-line treatment for OSA.     

Neuromuscular ventilatory insufficiency: effect of home mechanical ventilator use v oxygen therapy on pneumonia and hospitalization rates

The purpose of this study was to determine rates of pneumonia and hospitalization for patients receiving oxygen therapy, patients having indwelling tracheostomy tubes, and those using tracheostomy or noninvasive methods of home mechanical ventilation. Six hundred eighty-four users of assisted ventilation for 13,751 patient-years or 19.8 years per patient were surveyed by mail and twice by telephone over a span of four years. Pneumonia and hospitalization rates were significantly higher for ventilator users with chronic obstructive pulmonary disease or with neuromuscular ventilatory insufficiency and gastrostomy tubes than for ventilator users with neuromuscular ventilatory insufficiency without gastrostomy tubes. Of the latter group, more than 90% of the pneumonias and hospitalizations were triggered by otherwise benign intercurrent upper respiratory tract infections. Oxygen therapy was associated with a significantly (P < 0.001) higher rate of pneumonias and hospitalizations than that seen for untreated patients after initial episodes of respiratory distress or during the use of either tracheostomy intermittent positive pressure ventilation or noninvasive ventilatory assistance methods. The lowest pneumonia and hospitalization rates (P < 0.001) were by full-time, noninvasive intermittent positive pressure ventilation users. We conclude that oxygen therapy is not an effective substitute for assisted ventilation for patients with primarily ventilatory insufficiency. Noninvasive ventilatory aids can be used effectively for up to full-time ventilatory support for patients with neuromuscular conditions whose bulbar muscle function is adequate to avert the need for gastrostomy tube placement.     

Can laparoscopic cholecystectomy be a day surgery procedure?

BACKGROUND/AIMS: Gallbladder surgery by videolaparoscopy (VL) is now able to obtain the same goals as traditional surgery, and is associated with comparable or better results both in terms of positive surgical outcome and patient satisfaction. With public health spending under growing social and administrative pressure, and continuous efforts focusing on enhancing the efficiency of both surgical instruments and operating procedures, it is a most attractive, albeit initially challenging, prospect to regard video-laparoscopic surgery as day-case surgery. Herein, the authors assess the outpatient treatment option, due to recent technical developments and relevant major organizational and professional implications, and consider the feasibility of day-case surgery projects which should soon be implemented. METHODOLOGY: From January 1994 to December 1996, 1,334 patients underwent videolaparoscopic cholecystectomy. Of these, 898 were women and 436 men. In 1,034 of the laparoscopies gas was used and 300 were performed without gas. Out of the total 1,334 patients who were submitted to the videolaparoscopic cholecystectomy procedure with or without the use of gas, 72 (5.4%) were treated on an outpatient basis. RESULTS: In our series, 93.5% of patients reported normal post-operative functions within 24 hours; 90.2% of patients were able to take oral fluid on the same day of the operation and had normal bowel peristalsis within the first post-operative day. CONCLUSIONS: The authors assess the outpatient option treatment, due to recent technical developments and relevant major organizational and professional implications, and consider the feasibility of a day-case surgery project which should soon be implemented.     

Venous leg ulcers. Part 1: Aetiology

Cardiogenic pulmonary edema is a frequent cause of reparatory failure. We investigated the effects of nasal continuous positive airway pressure (CPAP) in patients with severe pulmonary edema associated with acute myocardial infarction. Twenty-nine consecutive patients were divided into 3 groups: firstly, 7 intubated patients who received mechanical ventilation at study entry comprised the intubation group. The rest of the patients were randomly assigned to either of the following 2 groups: 11 patients who received oxygen plus CPAP delivered by a nasal mask (CPAP group), and 11 patients who received oxygen only via face mask (oxygen group). All patients in the intubation group had cardiogenic shock. Two patients (18%) in the CPAP group and 8 patients (73%) in the oxygen group required mechanical ventilation with endotracheal intubation (p=0.03). The hospital mortality rate in the CPAP group (9%) was significantly lower than the oxygen group (64%, p=0.02). The pulmonary artery wedge pressure and heart rate were significantly lower in the CPAP group than in the oxygen group 24 h after study entry (p<0.05 and p<0.01). The mean pulmonary artery pressure 48 h after study entry was 18+/-5 mmHg in the CPAP group and 25+/-8 mmHg in the oxygen group (p<0.05). The PaO2/FiO2 ratio increased in the intubation group (168+/-69 to 240+/-57, p<0.05) and the CPAP group (137+/-17 to 253+/-67, p<0.01) 24 h after study entry. Arterial plasma endothelin-1 concentrations decreased significantly earlier in the CPAP group than in the oxygen group (p<0.05). In patients without cardiogenic shock, nasal CPAP lead to an early improvement in oxygenation and hemodynamics, and decreased the mortality rate. Early and active respiratory management is recommended in patients with pulmonary edema associated with acute myocardial infarction.     

Noninvasive ventilation for postoperative support and facilitation of weaning

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

3 years of long-term home oxygen therapy in the Czech Republic

BACKGROUND: Long-term domiciliary oxygen therapy was introduced in the Czech Republic as a standard therapeutic method in patients with chronic respiratory failure in October 1992. As a source of oxygen almost exclusively oxygen concentrators are used which are allocated to the patients according to criteria elaborated by the European Respiratory Society. METHODS AND RESULTS: From October 1, 1992 to October 1, 1995 the mean number of installed concentrators is 10,24/100000 population. From a total of 1064 patients by October 1, 1995 3.8% were treated for three years, 20.7% for two years and 34.4% for more than one year. In the course of three years a total of 490 patients died. The mean survival period of patients treated for prolonged periods by domiciliary oxygen therapy was 8.88 months. The high mortality rate is due to the fact that patients in a very serious state are treated. On account of chronic pulmonary disease oxygen therapy was indicated in 93.4%, on account of interstitial pulmonary processes (KFA and other fibroses) in 3.9, on account of kyphoscoliosis in 2.4% and on account of cystic fibrosis in 0.3% of the group. The mean costs of treatment were 114.40 K?/day which is a third of the costs when the patient is hospitalized. CONCLUSIONS: Domiciliary oxygen therapy proved effective and economical in patients with chronic respiratory failure.     

Tracheal pressure triggering a demand-flow continuous positive airway pressure system decreases patient work of breathing

OBJECTIVES: Triggering a ventilator "ON" at the carinal end of the endotracheal tube decreases imposed work of breathing by bypassing the resistance imposed by the breathing circuit and the endotracheal tube. We compared work of breathing during spontaneous ventilation between three methods of triggering the ventilator "ON": a) conventional pressure triggering from inside the ventilator; b) flow-by triggering; or c) tracheal pressure triggering at the carinal end of the endotracheal tube. We hypothesized that the work of breathing would be substantially decreased with tracheal pressure triggering compared with conventional pressure and flow-by methods in patients receiving continuous positive airway pressure. DESIGN: Clinical, prospective study. SETTING: University teaching hospital. PATIENTS: Fourteen adults diagnosed with acute respiratory failure. INTERVENTIONS: All patients were breathing spontaneously at an FIO2 of 0.30 to 0.40 and received 5 cm H2O of continuous positive airway pressure. Three different methods of triggering the ventilator while set in the continuous positive airway pressure mode were administered in random order. MEASUREMENTS AND MAIN RESULTS: Real-time measurements of esophageal pressure and tidal volume were integrated with a respiratory monitor (CP-100, Bicore, Riverside, CA) that uses the Campbell diagram to calculate total work of breathing. Imposed work of breathing was calculated by integrating tidal volume with the pressure at the carinal end of the endotracheal tube. Physiologic work of breathing was calculated by subtracting imposed work of breathing from the total work of breathing. Breathing frequency, the index of rapid shallow breathing (breathing frequency/tidal volume), peak inspiratory flow rate demand, exhaled minute ventilation, and the duration of respiratory muscle contraction assessed by the ratio of inspiratory time to total cycle time were also measured. Data were analyzed by Friedman's repeated-measures analysis of variance on ranks. Alpha was set at .05 for statistical significance. Imposed work of breathing decreased to approximately zero during tracheal pressure triggering. As a result, total work of breathing decreased by approximately 40% compared with the flow-by and conventional methods. During tracheal pressure triggering only, airway pressure increased above baseline pressure to approximately 11 cm H2O, which resembled pressure-support ventilation. Also, during tracheal pressure triggering, tidal volume and peak inspiratory flow rate were significantly increased, while the pressure-time product and the index of rapid shallow breathing were significantly decreased. Hemodynamic status and oxygen saturation were not clinically affected. CONCLUSIONS: The tracheal pressure triggering of a demand-flow continuous positive airway pressure system creates an effect similar to pressure-support ventilation that significantly decreases imposed work of breathing and, thus, total work of breathing. We recommend moving the triggering site of the ventilator to the carinal end of the endotracheal tube.     

Non-invasive nasal ventilation in a a case of hypercapnic coma

Noninvasive positive pressure ventilation (NPPV) via nasal mask is well known to be effective in the treatment of acute respiratory failure (ARF) secondary to chronic obstructive pulmonary disease (COPD). A case of ARF with hypercapnic coma due to exacerbation of COPD is described. Six hours of conservative therapy with oxygen and medical treatment did not show any result. As endotracheal intubation (ET) was avoided on the basis of advanced age, poor life expectancy of the patient and family wish, NPPV was set up using a pressure triggered ventilator. After 61 hours of uninterrupted NPPV, the acid-base alteration and the lethargic status was fully reversed. The conclusions is drawn that NPPV may be useful also in the treatment of patients affected by severe decompensated hypercapnic respiratory failure in whom ET is not indicated.     

Effect of side chain location in (2-aminoethyl)-aminomethyl-2-phenylquinolines as antitumor agents

New equipment facilitating the use of spontaneous ventilation with positive expiratory pressure (PEP) has become available in France since January 1996. This technique was applied in 38 patients with severe cardiogenic pulmonary oedema and persistent respiratory distress despite high flow classical oxygen therapy and standard treatment. After 1 hour of ventilation with a flow of 220 l/min of 100% oxygen with an average PEP of 7.7 cm H20, a significant improvement of clinical (heart and respiratory rate) and biological parameters (arterial gases) was observed. There were no side effects. Four patients died during the hospital period and only 1 was intubated. Spontaneous ventilation with PEP is a simple technique for coronary care units and, compared with conventional oxygen therapy, it rapidly improves arterial oxygenation, reduces respiratory work and improves conditions of cardiac load. Acute severe cardiogenic pulmonary oedema seems to be an indication of choice, especially in the elderly, where it may help avoid an often controversial intubation.     

Non-invasive modalities of positive pressure ventilation improve the outcome of acute exacerbations in COLD patients

OBJECTIVE: 1) To compare the clinical usefulness of both non-invasive pressure support ventilation (NPSV) and non-invasive intermittent positive pressure ventilation in assist-control (A/C) mode (NIPPV) in chronic obstructive lung disease (COLD) patients with acute hypercapnic respiratory failure: 2) to compare retrospectively the usefulness of non-invasive mechanical ventilation (NMV) with standard medical therapy alone. DESIGN: Prospective randomized retrospective study. SETTING: 2 Respiratory intermediate intensive units. PATIENTS: 29 COLD patients (age: 62 +/- 8 years) with chronic respiratory failure were hospitalized in a department for rehabilitation during acute relapses of their disease. They were transferred to our intermediate intensive care unit (IICU) and submitted randomly to either NPSV (16 patients) or NIPPV (13 patients). MEASUREMENTS AND RESULTS: Blood gas analysis, dynamic flows, clinical variables, success rate, time of ventilation, side effects and subjective score of compliance to therapy. Therapy was considered successful when endotracheal intubation was avoided and patients were returned to their condition prior to exacerbation. No statistically significant difference was found between NPSV and NIPPV in success rate (NPSV 87.5%; NIPPV 77%) or in time of ventilation (NPSV: 69 +/- 49; NIPPV: 57 +/- 49 h). A better compliance to non-invasive mechanical ventilation (NMV) was found in NPSV patients than in NIPPV patients; side effects were observed less frequently in the NPSV group. Comparison of the success rate of NMV was retrospectively performed with 35 control COLD patients with chronic respiratory insufficiency who had undergone an acute relapse of their disease in the 2 years preceding the institution of the IICU and had been treated with oxygen and medical therapy alone. Patients submitted to NMV showed a greater success rate than control (82 versus 54%) after a period of ventilation ranging from 4-216 h. CONCLUSION: Non-invasive mechanical ventilation performed either by NPSV or NIPPV may improve the outcome of acute exacerbations of COLD, as compared to medical therapy alone. NPSV seems to be more acceptable to patients in comparison with NIPPV.     

Assessment of the nutritional state of dialysis patients

Obstructive sleep apnea syndrome (OSAS) has been associated with a higher than normal cardiovascular morbidity and mortality. Some OSAS patients lack the sleep-related, nocturnal decrease, or "dip," in blood pressure which is seen in normal individuals. These subjects, called "non-dippers," may be at greater risk for cardiovascular problems. We studied 40 OSAS patients (including 3 women) and 6 control subjects, all identified by polysomnography, for nocturnal blood pressure "dipping." We performed a second nocturnal polysomnogram to determine their apnea and hypopnea indices, (A + H)I, and oxygen saturation levels at the beginning of the study and then initiated 48 hours of ambulatory blood pressure monitoring, with data points collected every 30 minutes. Controls, which included one hypertensive subject, were all dippers. Nineteen OSAS subjects (48% of OSAS individuals) were systolic non-dippers and only 9 of them (22.5%) were diastolic non-dippers. We considered the following clinical variables as potential predictors of non-dipping: age, body mass index, respiratory disturbance index, years of reported loud snoring by bed partners, lowest oxygen saturation during nocturnal sleep, and percentage of sleep time spent with oxygen saturation below 90%. Multiple regression analyses indicated respiratory disturbance index as the only significant variable for systolic (p = 0.04) and diastolic (p = 0.03) blood pressure non-dipping. When we forced the following two nonsignificant variables into the model, they showed a very meager impact: number of years with reported loud snoring (p = 0.4 and p = 0.5, respectively for systolic and diastolic blood pressure non-dipping) and age (p = 0.5 and p = 0.6). The calculated model explained only a low percentage of the variance with an r2 of 0.25 and 0.26 for systolic and diastolic blood pressure non-dipping, respectively. Analysis of hypertension/normotension and dipping/non-dipping failed to show a significant relationship in the studied population. Fifty percent of the normotensive OSAS subjects were non-dippers and 43% of the hypertensive OSAS subjects were also non-dippers. We found a relationship between increasing respiratory disturbance index and increasing average 24-hour systolic blood pressure only when OSAS subjects were non-dippers and hypertensive.     

Effects of respiratory alkalosis and acidosis on myocardial blood flow and metabolism in patients with coronary artery disease

BACKGROUND: Variation of the arterial carbon dioxide partial pressure (PaCO2) is not uncommon in anesthetic practice. However, little is known about the myocardial consequences of respiratory alkalosis and acidosis, particularly in patients with coronary artery disease. The aim of the current study was to investigate the effects of variation in PaCO2 on myocardial blood flow (MBF), metabolism, and systemic hemodynamics in patients before elective coronary artery bypass graft surgery. METHODS: In 10 male anesthetized patients, measurements of MBF, myocardial contractility, metabolism, and systemic hemodynamics were made in a randomized sequence at PaCO2 levels of 30, 40, and 50 mmHg, respectively. The MBF was measured using the Kety-Schmidt technique with argon as a tracer. End-diastolic left ventricular pressure and the maximal increase of left ventricular pressure were assessed using a manometer-tipped catheter. RESULTS: The cardiac index significantly changed with varying PaCO2 levels (hypocapnia, - 9%; hypercapnia, 13%). This reaction was associated with inverse changes in systemic vascular resistance index levels. The MBF significantly increased by 15% during hypercapnia, whereas no change was found during hypocapnia. Myocardial oxygen and glucose uptake and the maximal increase of left ventricular pressure were not affected by varying PaCO2 levels. CONCLUSIONS: In anesthetized patients with coronary artery disease, short-term variations in PaCO2 have significant effects on MBF but do not influence global myocardial oxygen and glucose uptake. Changes in systemic hemodynamics associated with respiratory alkalosis and acidosis are caused by changes in systemic vascular resistance rather than by alterations in myocardial contractility.     

Compliance in treatment of the sleep apnea syndrome using continuous positive pressure respiration

BACKGROUND: Continuous positive airway pressure (CPAP) is the therapeutic method of choice in sleep apnoea syndrome (SAS) but involves at first discomfort for the patients. The correct indication, correct setting of the overpressure and good adaptation influence the application and therapeutic asset of CPAP. METHODS AND RESULTS: From a total number of 41 patients with SAS treated by CPAP 24 were examined (incl. three women), who had CPAP in domiciliary treatment for more than two months. The mean period of use was 288.2 days (range 52-824). 84% of the patients used CPAP daily, the mean number of applications per week was 6.26 (range 2-7). For the whole period of sleep CPAP was used by 75% patients and the mean sleep period with CPAP was 6 hours (range 2.5-8). None of the patients discontinued treatment completely. Four patients used CPAP inadequately (less than 25 hours per week) - one because of intolerance associated with severe CHOCHB, the second one for intolerance of overpressure of 15 mbar, the third one because of poor motivation and the fourth one because of dehydration of mucous membranes. All patients recorded the therapeutic effect of CPAP. Rhonchopathy disappeared in 87.5% patients, excessive somnolence improved in 91.7%, fatigue declined in 88.5%. The functional capacity and work performance improved in 95.8% patients. Undesirable effects were not serious nor frequent: escape of air from the mask (29.2%), dry mucosae (20.8%), pressure sores caused by the mask (20.8%), serous rhinitis (12.5%), burning sensation of the mucosae of the upper airways (8.3%) and conjunctivitis (4.2%) CONCLUSIONS: Adequate compliance with CPAP was recorded in 83.3% patients and a favourable effect of treatment was proved.     

Obstructive sleep apnea. Warding off the sometimes dire consequences

Obstructive sleep apnea (occlusion of the upper airway despite continued respiratory muscle activity) is accompanied by increased morbidity and mortality from cardiovascular and cerebrovascular disease. Daytime sleepiness due to the disorder may also be a factor in a higher incidence of automobile accidents in these patients. An overnight polysomnogram is used to confirm the diagnosis and assess severity of physiologic disturbances. Initially, simple measures, such as avoidance of alcohol and sedatives before bedtime and sleeping on the side rather than the back, may be tried. Nasal continuous positive airway pressure is considered first-line therapy, and compliance can be improved by education and counseling of the patient. Uvulopalatopharyngoplasty is beneficial in only 50% of patients. Tracheostomy gives the most consistent long-term benefit but is accompanied by significant emotional morbidity.     

Influence of carotid atheroma on the neurologic status after myocardial revascularization

Surgical management of the carotid disease remains controversial in patients affected with coronary artery atheromatous disease. We report the Montreal Heart Institute experience on the influence of carotid disease on postoperative neurologic events of 501 consecutive patients operated on for coronary revascularization during the period from January 1994 to December 1994. There were 381 men and 114 women averaging 62 +/- 9 years old. Major risk factors were high blood pressure (35%), and smoking habit (48%). Fifty-nine patients presented clinical signs of carotid atheromatosis and among them 21 had significant carotid stenosis (> 80% decrease of cross sectional area). During surgery, the mean duration of extracorporeal circulation (ECC) was 76 +/- 31 minutes and the mean perfusion pressure (MPP) was 70 +/- 11 mmHg. The use of inotropic drugs was mandatory in 26% of the cases and the mean arterial lactate (AL) dosage during ECG was 3.07 +/- 1.35 mM/L. During the perioperative period, 13 (2.5%) patients sustained neurologic disturbances of which 5 (1%) were lateralized. Among them, 8 completely recovered whereas 3 of the 5 with permanent damage died. None of the patients with preoperative stigmata of carotid disease experienced lateralized neurologic deficit. Multivariate regression analysis identified the use of vasopressor drugs and perioperative increase of AL as predictive factors. We conclude that in our series, the incidence of neurologic complications was low. The presence of carotid atheromatosis did not increase the postsurgical risk of cerebrovascular accident, however, the increased incidence of neurologic events associated with inotropic drugs and increased AL suggests a direct link with a systemic oxygen debt. Consequently, we do no recommend concurrent prophylactic surgery during coronary artery revascularization.