Hemodynamic changes during laparoscopic cholecystectomy

Hemodynamics during laparoscopic cholecystectomy under general anesthesia (isoflurane in N2O/O2 (50%)) were investigated in 15 nonobese ASA Class I patients by using invasive hemodynamic monitoring including a flow-directed pulmonary artery catheter. During surgery, intraabdominal pressure was maintained automatically at 14 mm Hg by a CO2 insufflator, and minute ventilation was controlled and adjusted to avoid hypercapnia. Hemodynamics were measured before anesthesia, after the induction of anesthesia, after tilting into 10 degrees head-up position, 5 min, 15 min, and 30 min after peritoneal insufflation, and 30 min after exsufflation. Induction of anesthesia decreased significantly mean arterial pressure and cardiac index (CI). Tilting the patient to the head-up position reduced cardiac preload and caused further reduction of CI. Peritoneal insufflation resulted in a significant increase (+/- 35%) of mean arterial pressure, a significant reduction (+/- 20%) of CI, and a significant increase of systemic (+/- 65%) and pulmonary (+/- 90%) vascular resistances. The combined effect of anesthesia, head-up tilt, and peritoneal insufflation produced a 50% decrease in CI. Administration of increasing concentrations of isoflurane, via its vasodilatory activity, may have partially blunted these hemodynamic changes. These results demonstrate that laparoscopy for cholecystectomy in head-up position results in significant hemodynamic changes in healthy patients, particularly at the induction of pneumoperitoneum.     

Perspectives in mechanical ventilation in ARDS

Despite more than 25 years of extensive research, the mortality of ARDS patients remains high. The inflammatory process within the lung and the associated gas exchange disturbances require an aggressive ventilatory regimen, which itself may harm the lung. Therapeutic measures which are used to reduce iatrogenic damage to the lung are pressure controlled mechanical ventilation in combination with PEEP and permissive hypercapnia, dehydration and extracorporeal gas exchange. At present, new strategies such as intratracheal instillation of surfactant, partial liquid ventilation and inhalation of nitric oxide (NO) are being evaluated. Surfactant reduces the surface tension, forming a monomolecular layer at the air/tissue interface. It thereby decreases the forces necessary to expand the alveoli and prevents alveoli with small diameter from collapsing. In ARDS, a disturbance of surfactant synthesis, function and re-uptake is the rationale for treatment with exogenous surfactant. Initial clinical results suggest a limited positive effect independently of the surfactant preparation used, the dose and the application mode. Experience with partial liquid ventilation with perfluorocarbons in ARDS has also been reported. Perfluorocarbons are liquids with a high binding capacity for oxygen and carbon dioxide. During normal mechanical ventilation with gas, repetitive doses of perfluorocarbons are instilled into the lungs up to a volume equal to the functional residual capacity. The liquid is pushed into collapsed alveoli and keeps them open by reducing the surface tension. First clinical studies have demonstrated the possible improvement in pulmonary gas exchange. In ARDS, inhalation of NO may cause a predominantly selective vasodilation in blood vessels of ventilated lung regions, resulting in an increase in PaO2 and a decrease in pulmonary artery pressure. The effect of NO on the pulmonary vasculature also induces a reduction in right ventricular afterload and also in pulmonary capillary pressure, which may lead to a faster resolution of pulmonary edema. However, in spite of the promising results of these new strategies, further studies are needed to evaluate their influence on morbidity and mortality.     

Effects of phospholipid base analogues on the subcellular membrane ether composition of suspension cultured LM cells

Morbidity and mortality from pulmonary complications following urinary tract operations can be reduced by preoperative identification of the high risk patient. Pulmonary function tests and arterial blood gases are necessary to identify these patients and to delineate the severity of their pulmonary disease. Respiratory complications can be prevented in many patients with the proper use of pre- and postoperative chest physical therapy and oxygen therapy. Despite the most careful pulmonary management, some patients develop acute respiratory failure following urologic operations. Respiratory failure results from a combination of physiologic abnormalities which impair alveolar ventilation and oxygenation. Utilizing controlled ventilation, supplemental oxygen, and a physiologic approach to treating the underlying cause of respiratory failure, three fourths of urologic patients in respiratory failure may be expected to survive.     

Pathophysiological and clinical aspects of the CO2 pneumoperitoneum (CO2-PP)

Experimental studies demonstrated a severe cardiac load of the CO2 pneumoperitoneum caused by an accelerated after- and a decreased preload. Patients displaying cardiovascular risks are therefore often rejected from laparoscopic surgery. Hence, the pathophysiological changes and the intraoperative risk of the CO2 pneumoperitoneum in high-risk cardiopulmonary patients (NYHA II-III, n = 15) undergoing laparoscopic cholecystectomy are described. The changes in cardiac after- and preload seem to be due to the elevated intraabdominal pressure rather than transperitoneally resorbed CO2 and are reversible by desufflation. In one patient conversion to open operation had to be performed because of a severe drop in cardiac output and right ventricle ejection fraction. Mixed oxygen saturation was predicting intraoperative worsening in this case. The described pathophysiological changes may seem to be well tolerated even in high-risk cardiac patients. Monitoring of hemodynamics should include an arterial catheter line and blood gas analyses. Pharmacologic interventions or pressureless laparoscopic procedures might not be necessary as long as laparoscopic cholecystectomy is performed.     

Lung contusion in the multiple trauma patient

The main management's characteristics of the pulmonary contusion in the trauma patients are explained. From possible alveolocapillary membrane's injuries, with consideration of worsening evolution (ARDS, nosocomial infection, MOF), main points of discussion are circulation and mechanical ventilation. For the most severely injured, invasive monitoring is necessary, including the oxygenation parameters we now can dispose of. Quantification of extravascular lung water is an original and valuable tool to determine the time course and amount of pulmonary oedema. There is no ideal mode of ventilation but the basic ventilatory patterns must be adjusted; a target is the reduction of time requirement for ventilatory support.     

Should laparoscopic appendectomy be avoided for complicated appendicitis in children?

BACKGROUND/PURPOSE: Laparoscopic appendectomy is becoming the preferred technique for treating acute appendicitis. However, recent literature on adults suggests that laparoscopic appendectomy may increase the risk for postoperative infectious complications in complicated (gangrenous or perforated) cases. This study was undertaken to compare the results of open versus laparoscopic appendectomy for complicated appendicitis in children. METHODS: A retrospective review from two institutions was performed for all children treated operatively for complicated appendicitis from January 1994 through November 1996. RESULTS: Fifty-six cases were identified. Twenty-seven children underwent laparoscopic appendectomy, whereas 22 underwent open appendectomy. Seven children underwent conversion from laparoscopic to open surgery. Operating times and length of hospital stay did not differ significantly between the laparoscopic and open groups. Postoperative complications developed in 24 children (42.8%). Complications were more frequent after laparoscopic appendectomy compared with open appendectomy (56% v 18%, P = .002). A postoperative intraabdominal abscess (IAA) developed in 14 children (25%). An IAA occurred in two children after open appendectomy compared with 11 children after laparoscopic appendectomy (9% v 41%, P = .01). CONCLUSION: The findings suggest that laparoscopic appendectomy should be avoided in children who have complicated appendicitis because of the increased risk for postoperative intraabdominal abscesses. The authors propose a prospective, randomized trial to verify this finding.     

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.     

Pneumoperitoneum risk prognosis and correction of venous circulation disturbances in laparoscopic surgery. A pilot study

BACKGROUND: This study was initiated to find a method of determining the prognosis for possible changes in hemodynamic and respiratory parameters in patients with pneumoperitoneum (PP). METHODS: We devised a model for a pseudopneumoperitoneum (PPP), which is created by encircling the wide pneumochamber on the entire abdomen and inflating it to a preset pressure. To verify the prognostic possibilities of the proposed model, we studied the pneumotachygraphy parameters, noninvasive and invasive monitoring parameters of PPP after induction of anaesthesia, and venous circulation disturbances, as well as the medical effect of the intermittent sequential compression device. RESULTS: In healthy patients, the restrictive lung syndrome did not approach the risky limit. In patients >/=60 years old, this syndrome was very close to the limit. In a number of patients with serious cardiovascular and pulmonary pathology, the pressure of >10 mmHg was considered to be intolerable. Lung compliance, which was the parameter most sensitive to the increased intraabdominal pressure, was 47 +/- 10 at baseline, and 29 +/- 4 (p > 0.05) at both PPP and real PP (14 mmHg). CONCLUSIONS: The PPP model is quite similar to the real PP and can be used for preoperative prognosis in laparoscopic surgery. The elevated intraabdominal pressure results in a significant disturbance of venous blood flow in the lower extremities. The use of the device for peristaltic pneumomassage of the lower limbs is effective in correcting negative changes in venous hemodynamics in laparoscopic surgery.     

Intraabdominal carbon dioxide insufflation in the pregnant ewe. Uterine blood flow, intraamniotic pressure, and cardiopulmonary effects

BACKGROUND: Laparoscopic surgical procedures are being performed in pregnant women with increasing frequency. Maternal-fetal physiologic changes occurring during intraabdominal carbon dioxide insufflation are poorly understood, and maternal-fetal safety is of concern during carbon dioxide pneumoperitoneum. A previous pilot study using end-tidal carbon dioxide-guided ventilation resulted in maternal and fetal acidosis and tachycardia during carbon dioxide pneumoperitoneum. Using serial arterial PCO2 to guide ventilation, this study was designed to evaluate maternal-fetal cardiopulmonary status, uterine blood flow, and the intraamniotic pressure effects of intraabdominal carbon dioxide insufflation in singleton pregnant ewes between 120 and 135 days of gestation. METHODS: In a prospective randomized cross-over study, nine ewes were to receive either abdominal insufflation with carbon dioxide to an intraabdominal pressure of 15 mmHg (n = 9; insufflation group) or receive no insufflation (n = 9; control group). Anesthesia was induced with thiopental and maintained with end-tidal halothane (1 to 1.5 minimum alveolar concentration/100% oxygen). Mechanical ventilation was guided by serial maternal arterial blood gas analysis to maintain PaCO2 between 35 and 40 mmHg. Data from insufflated animals were collected during insufflation (60 min) and after desufflation (30 min). Control group data were collected and matched to similar time intervals for 90 min. Ewes were allowed to recover, and after a rest period (48 h) they were entered in the cross-over study. RESULTS: During insufflation there was a significant increase (P < 0.05) in maternal PaCO2 to end-tidal carbon dioxide gradient and minute ventilation, with concomitant decreases in maternal end-tidal carbon dioxide and PaO2. Intraamniotic pressure increased significantly during insufflation. No significant changes were observed in maternal hemodynamic variables, fetal variables, or in uterine blood flow during the study. There were no fetal deaths or preterm labor in any of the animals during the experiment. CONCLUSIONS: During the 1-h insufflation, a marked increase in PaCO2-to-end-tidal carbon dioxide gradient was observed, suggesting that capnography may be an inadequate guide to ventilation during carbon dioxide pneumoperitoneum in the pregnant patient. No other significant circulatory changes were observed.     

Persistent pulmonary hypertension in newborn infants

On the basis of a review of the literature, a survey is presented concerning persistent pulmonary hypertension of the newborn. In this article the authors focus on the pathophysiology, diagnostic criteria and treatment, including mechanical ventilation, pharmacological vasodilation and extracorporal membrane oxygenation. Particular emphasis is placed on the treatment of the condition with inhaled nitric oxide. Nitric oxide is a selective pulmonary vasodilator and able to improve ventilation/ perfusion mismatching in cases where there is an affection of the pulmonary parenchyma. Data from randomized trials with close long-term follow-up is necessary before routine nitrogen oxide treatment can be recommended.     

Physiopathology of pulmonary emphysema. Analysis of structural changes in the pulmonary architecture and therapeutic implications

In the pulmonary emphysema a serious respiratory inadequacy can result from the impossibility of the thoracic cage and of the diaphragm to expand beyond a maximum limit, before that a significnat part of pulmonary parenchyma has been destroyed by the pathogenic process. The resection of part of the lung, selectively in the areas where the emphysematous injuries are more pronounced, brings again the ventilation of the residual pulmonary parenchyma toward more physiological expansion values of the thoracic cage and diaphragm, thus decreasing the respiratory work, improving the ventilation mechanics and the bronchial obstruction. The time duration of the improvement achieved with the lung volume reduction is still to be demonstrated. A clinical and therapeutic analysis of this pathology is carried out.     

Volume reduction surgery in the native lung after single lung transplantation for emphysema

The natural history of emphysema suggests that progression of disease in the native lung may contribute to late deterioration in respiratory function after single lung transplantation. In this report, we describe our experience with unilateral volume reduction surgery in three single lung transplant recipients with emphysema. Each patient had had a late decline in lung function with a recurrence of symptoms. Chest radiographs demonstrated hyperinflation of the native lungs with encroachment on the grafts. Serial pulmonary function testing documented progressive reduction in expiratory flows with increases in residual volumes. Exercise testing confirmed severe intolerance to maximal exercise. Unilateral volume reduction surgery was undertaken at 36, 39, and 55 months after transplantation without incident. Radiographs obtained after the procedures demonstrated restoration of normal diaphragmatic contour, decreased aeration of the native lungs, and improved inflation of the allografts. Exercise testing at 3 months documented a mean improvement in maximal oxygen consumption of 35%. Expiratory flows improved by a mean of 60%. Quantitative ventilation and perfusion scans, however, were essentially unchanged. This experience suggests that unilateral volume reduction surgery may be considered as an alternative strategy in single lung transplant recipients with emphysema who exhibit clinically significant functional deterioration. Differentiation of the adverse effects of hyperinflation of the native lung from other potential causes of late deterioration might not be necessary but may be predictive of the degree of functional improvement after volume reduction. The relief of thoracic overdistention seems to play a primary role in the improvement pulmonary function.     

The impact of working with people with HIV/AIDS: a review of the literature

The increasing use of laparoscopic surgery in children is associated with the enlargement of the spectrum of indications to appendicectomy, extramucosal pylorotomy and cure of oesophageal reflux. It is also linked with new problems, mainly due to physiologic modifications elicited by pneumoperitoneum and patient's posture. Although sufficient data are not yet available, the respiratory and cardiovascular modifications are probably similar to those occurring in adults, at least in children more than 4-month-old, as long as the intra-abdominal pressure remains under 15 mmHg. The use of higher intra-abdominal pressures has not been reported in children. In this case, the cardiovascular changes consist mainly in an increase in arterial pressure. In some children, non specific decreases in heart rate and in blood pressure can be observed. The latter can be elicited by a surgical complication, hypovolaemia, head-elevated position or deep anaesthesia. In the newborn and infant under 6 months, intra-abdominal pressures of 15 mmHg or more carry a risk of low cardiac output due to a decrease in contractility and compliance of the left ventricle. In this group of age it is therefore recommended to establish a pressure not higher than 6 mmHg. Moreover, in these very young children, the risk for reopening of the right-left shunts can result in heart insufficiency and systemic gas embolism. Peroperative respiratory changes include an increase in PetCO2 and more rarely a decrease in SaO2. The interpretation of the former depends on the site of gas sampling in the anaesthetic system. It is easily controlled by an increased minute ventilation. Various causes, such as bronchial intubation, inhalation of gastric contents or gas embolism, can decrease SaO2. Contra-indications for laparoscopic surgery include hypovolaemia, heart diseases, increased intracranial pressure and alveolar distension. Therefore newborns are patients at high risk in so far as their foramen ovale or their ductus arteriosus is patent, the pulmonary arterial resistances remain increased and a bronchodysplasia is existing. In some cases a special disease is often associated. As an example recurrent bronchitis or asthma is associated with an oesophageal reflux and a sickle-cell disease in patients with cholelithiasis. These patients require special pre-, per- and postoperative care for prevention of complications. Anaesthesia for laparoscopic surgery does not require a major extension of the usual security regulations. Special attention must be paid to arterial pressure. Therefore end-expiratory concentration of the halogenated anaesthetic agent should not be kept higher than 1.5 times the MAC related to the age during maintenance of anaesthesia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Methods of analysis and resources available for genetic trait mapping

Stones can be spilled from the gallbladder during laparoscopic cholecystectomy. These stones can be left in the peritoneal cavity or trapped at the trocar site. The potential late sequel and associated morbidity are not well documented. We reviewed the records of four patients who underwent laparoscopic cholecystectomy at Mount Sinai Medical Center in New York City who suffered from late complications attributed to gallstones left in the peritoneal cavity or abdominal wall. Four patients presented 1-14 months after laparoscopic cholecystectomy with intraabdominal and abdominal wall abscesses. The spillage of gallstones was noticed during the initial operation only in one of the patients. Three patients required laparotomy and open drainage of intraabdominal abscesses with drainage of pus and gallstones after failed attempts at percutaneous drainage. Two patients underwent local exploration of an abdominal wall abscess containing stones. Stones left in the abdominal cavity or trapped in trocar sites after laparoscopic cholecystectomy can cause serious late complications requiring repeated surgical interventions. Every effort should be made in order to avoid spillage of stones during dissection of the gallbladder and cystic duct and during retrieval of the gallbladder through the abdominal wall.     

Ventilation of patients with asthma and obstructive lung disease

Mechanical ventilation in a patient with obstructive airway disease may be a lifesaving measure; however, it may also be associated with significant morbidity and mortality. It is important for a physician to be familiar with the potential complications of mechanical ventilation in this group of patients and to know how to avoid them by carefully applying safe ventilator strategies. The cornerstone of such strategies is to minimize minute ventilation, maximize time for expiration, and avoid hyperinflation of the lung. Several bedside parameters (iPEEP, VEI, Pplat) that reflect presence of gas trapping and potential hyperinflation may be measured. In addition to mechanical ventilation, management should include inhaled bronchodilators and systemic corticosteroid therapies. In the event controlled hypoventilation is necessary, sedation with or without the use of muscle relaxants may be required. Unconventional therapies such as the use of Heliox, magnesium sulfate, ketamine, and inhalational anesthetics may be attempted in severe cases that do not respond to conventional management. With appropriate use of ventilator strategies, a reduction in the mortality and morbidity of patients with obstructive airway disease requiring mechanical ventilation has recently been noted.     

Other laparoscopic bariatric procedures

Laparoscopic surgery is regarded as a major improvement reflected by a rapid recovery and low perioperative and postoperative morbidity. In obese patients the gains of this new technique may be affected by obesity-related problems, such as impaired respiratory function, high intraabdominal pressure, thick abdominal wall, and liver steatosis. This review describes the development of laparoscopic vertical banded gastroplasty (VBG) and gastric bypass procedures; and it addresses questions such as feasibility, comparability to open procedures, procedure-related problems, and recovery. The clinical outcome after laparoscopic VBG and gastric bypass is also updated. Up to May 1997 we have operated on 105 patients with laparoscopic VBG and another 26 completed laparoscopic gastric bypass procedures. The weight loss after both procedures are in accordance with the weight loss seen with open surgery. Procedure-related complications are described in detail in this paper. It is concluded that laparoscopic bariatric surgery will remain an area of importance for clinical practice, research, and development.     

The surgical physiopathology of essential pulmonary emphysema and volume-reduction intervention

The breaking of the interalveolar septa represents, in the pathogenetic mechanism of emphysema, a final event, common to the different etiologic agents. This elementary injury causes a series of consequences, essentially of mechanic-structural type (intrapulmonary aerial spaces-confining parenchyma collapse, bronchial obstruction, dead space augmentation) on the thin and articulate bronchoalveolar architecture, whose final rearrangement determines, at least in part, the clinical picture. In short, the break of alveolar septa involves the formation of intraparenchymal aerial spaces with collapse of the confining lung; the compensatory mechanism to this situation, involves the hyperexpansion of the thoracic cage and flattening of the diaphragm, with the aim of allowing ventilation of the healthy residual parenchyma. Because of the finite capability of expansion of the thoracic cage and of the diaphragm in respect to the theoretical capability of the lung of large intraparenchymal aerial spaces formation, it is easy to imagine that emphysema can cause a serious functional respiratory deficit even before a significant quantity of pulmonary parenchyma is destroyed by the pathogenic process. It may then be hypothesized that a simple reduction of the volume of the lung, even sacrificing a part of "working" parenchyma, might allow the residual lung to come back to a normal ventilation, wholly ameliorating the respiratory exchanges. The clinically more remarkable consequence of lung volume reduction is the amelioration of ventilation mechanics with a decreased respiratory work due to the shift of the tidal volume toward values less proximal to the maximal expandability of the thoracic wall and of the diaphragm. On the other end, it is possible to anticipate an equally significant effect on bronchial obstruction, due to the more favorable matching of the compliance of the thoracic wall and that of the lung. LVRS has significant effect on the TV sharing ratio between emphysematous spaces and residual healthy parenchyma; the hyperexpansion of the residual lung in fact causes the distension of the emphysematous spaces, continuing in the natural compensatory mechanism of the emphysema. The decreased ventilation and thus re-breathing of the residual emphysematous spaces, together with the improved ventilation may ameliorate hypercapnia. Obviously no direct effects can be expected from LVRS on the conditions of the alveolar membrane and thus on gas diffusion capacity through it. The time duration of the amelioration achieved with the lung volume reduction is still to be demonstrated.     

Role of luminal volume changes in the increase in pulmonary blood flow at birth in sheep

The mechanism by which pulmonary blood flow increases and pulmonary vascular resistance decreases after birth is not fully understood. The aim of this study was to simulate the decrease in lung volume caused by the onset of air-breathing at birth and determine whether it can duplicate the changes in pulmonary blood flow and vascular resistance that occur at this time. In chronically catheterized fetal sheep near term (145 days of gestation), fetal pulmonary arterial blood flow was measured, using coloured microspheres, before and after fetal lung liquid volumes were reduced from 52.2 +/- 2.7 to 21.2 +/- 1.6 ml kg-1. During the 30 min period following the reduction in lung liquid volume, the pulmonary-to-systemic arterial pressure difference decreased from 6.8 +/- 1.2 mmHg (pulmonary > systemic) to 1.6 +/- 0.5 mmHg. Reducing the volume of fetal lung liquid increased pulmonary blood flow from 59.1 +/- 10.5 to 204.2 +/- 40.4 ml min-1 (100 g tissue)-1 and reduced pulmonary vascular resistance from 0.53 +/- 0.20 to 0.14 +/- 0.04 mmHg min ml-1 (100 g tissue)-1. We conclude that a reduction in fetal lung liquid volume, which simulates the reduction in lung volume that occurs at birth, causes a 3- to 4-fold increase in pulmonary blood flow and a reduction in pulmonary vascular resistance of a similar magnitude. Thus, the reduction in lung volume associated with the lung changing from a liquid- to an air-filled organ, may partly account for the increase in pulmonary blood flow and decrease in pulmonary vascular resistance at birth.     

Intravenous nitroglycerin in acute respiratory failure of patients with chronic obstructive lung disease, secondary pulmonary hypertension and cor pulmonale

We have studied the hemodynamic effects of an intravenous single dose of nitroglycerin in 13 patients with secondary pulmonary hypertension and Cor Pulmonale, during the acute course of respiratory failure and under assisted ventilation. We observed a significant decrease in systolic, diastolic and mean pulmonary arterial pressures, and in pulmonary resistance and systolic right ventricular work index, without any change in right or left pre-loads. The systolic arterial pressure decreased slightly, without any change in cardiac index or diastolic pressure. The arterial and mixed venous oxygen contents, and the pulmonary shunting ( Qs/Qt) were unchanged. These results suggest that nitroglycerin may be a useful therapy in patients in the acute stages of pulmonary hypertension resulting from chronic lung disease and under assisted ventilation. In addition, the lack of change in cardiac index, intrapulmonary shunting and oxygen content suggests that this decrease in pulmonary resistance is not linked with any deleterious effect in oxygen transfer.     

The Chinese General Health Questionnaire in a psychiatric setting: the development of the Chinese scaled version

Hydroxyzine is frequently used to tranquilize chronic obstructive pulmonary disease patients, who may be concomitantly receiving narcotic analgesics. Therefore, its effect alone and in combination with meperidine on arterial blood gases and ventilation at rest were evaluated in 44 patient volunteers, who gave informed consent. Hydroxyzine, 1.5 mg/kg i.v. caused no significant decrease in PaO2 and pH, no increase in PaCO2 at 5, 10, 20, 30 and 60 min post-infusion (n = 13, mean age = 63.4 years). Meperidine, 1.5 mg/kg i.v. caused a significant (p < 0.001) reduction in PaO2 for 20 min with concomitant increase in PaCO2 (n = 14; mean age = 49.4 years). The combination of the same doses of hydroxyzine with meperidine i.v. caused no greater decrease in PaO2 or in pH or increase in PaCO2 than did meperidine alone (n = 17; mean age = 52.6 years), indicating no greater ventilatory depression with the combination than with meperidine alone. The lack of significant pH decreases at 30 and 60 min further corroborates no potentiation of meperidine by hydroxyzine. In conclusion, hydroxyzine, even when given through the i.v. route in excess of the maximum i.m. therapeutic dose, caused no changes in PaO2, PaCO2 or pH in chronic obstructive pulmonary disease patients. Therefore, its i.m. administration resulting in lower blood levels than i.v., is not likely to cause ventilatory depression. Furthermore, hydroxyzine caused no potentiation of the ventilatory depression induced by meperidine, hence hydroxyzine may be safely employed in combination with meperidine.