Ventilatory patterns during hypoxia, hypercapnia, and exercise in adolescents with mild scoliosis

Adolescents with mild, asymptomatic scoliosis (thoracic curvature less than 35 degrees) may have little or no impairment of resting lung volumes. Progression to more severe disease may, however, be accompanied by lung restriction, impaired exercise tolerance, and respiratory failure with CO2 retention. We wished to see whether adolescents with mild scoliosis and minimally abnormal resting pulmonary mechanics had impairment of their responses to hypercapnia, hypoxia, and progressive cycle exercise. Forty-four adolescents with idiopathic scoliosis were studied. The mean forced vital capacity (FVC), expressed as a percentage of the predicted value, was 94.3 +/- 2.2 (SE). The mean ventilatory response to hypercapnia (2.57 +/- 0.24 L/min/mm Hg) was within the normal range but was achieved with a tidal volume response (1.87 +/- .17% vital capacity [VC]/mm Hg) that was significantly lower than that previously reported in healthy young adults. Ventilatory responses to exercise were also within the normal range, the mean dyspnea index (VE-max/maximal voluntary ventilation) = 0.92 +/- 0.04. However, at a ventilation of 30 L/min, the tidal volume was 0.38 +/- 0.01% FVC, which was considerably lower than predicted. The tidal volume response to hypoxia was also abnormally low, the mean response being 0.52 +/- 0.059% VC/% decrease in arterial O2 saturation. These findings indicated that, even when scoliosis is asymptomatic and associated with minimal impairment of resting pulmonary function, abnormal patterns of ventilation occur during exercise or in response to chemical stimuli.     

Ventilatory response and arterial blood gases during exercise in children

To investigate the difference in ventilatory response to exercise between children and young adults, we administered a treadmill progressive exercise test to seven boys (aged 8 to 11 y [group A]) and six male young adults (aged 14 to 21 y [group B]), who had a history of Kawasaki disease without significant coronary arterial lesions, and analyzed their arterial blood gases. There was no significant difference in arterial PO2 or the end-tidal to arterial oxygen tension difference during exercise between groups A and B. The arterial PCO2 (PaCO2) at the ventilatory anaerobic threshold and at peak exercise was significantly lower in group A than in group B (p < 0.05). The arterial to end-tidal carbon dioxide tension difference at peak exercise was significantly greater in group B than in group A (p < 0.05), whereas there was no significant difference at rest or at the ventilatory anaerobic threshold level. The arterial to end-tidal carbon dioxide tension difference at peak exercise was correlated with tidal volume (p < 0.01) and carbon dioxide production (p < 0.05) at peak exercise in all subjects. Although improvement in the physiologic dead space/tidal volume ratio during exercise was smaller in group A than in group B, there was no significant difference in total alveolar ventilation during exercise. However, the total carbon dioxide production during exercise was significantly smaller in group A than in group B. These data suggest that PaCO2 during exercise is better estimated by end-tidal carbon dioxide tension in children than in young adults, that there is a significant difference in change of the PaCO2 during exercise between children and young adults, and that the decrease in PaCO2 in children is related to the mismatch between well-maintained alveolar ventilation and immature metabolic development in the working muscles during moderate-to-severe exercise.     

Exercise Performance Following Repair of Hypoplastic Left Heart Syndrome: A Comparison with Other Types of Fontan Patients

Reports of exercise performance after Fontan surgery for hypoplastic left heart syndrome (HLHS) are lacking. We compared the exercise performance of total cavopulmonary connection type (TCPC) of Fontan subjects with HLHS (group 1, n= 7) to those not requiring a Norwood procedure having a systemic right ventricle (group 2, n= 6) or a systemic left ventricle (group 3, n= 8). The subjects underwent assessment of resting pulmonary mechanics followed by maximal exercise testing with a bicycle or treadmill protocol. ECG, oxygen consumption, and carbon dioxide production were measured continuously. There was not a significant difference seen between HLHS and the comparison groups for the following parameters: maximum heart rate, maximum oxygen consumption, respiratory exchange ratio, breathing reserve, and arterial oxygen saturation at rest or exercise. Exercise performance in the TCPC type of Fontan patients was comparable regardless of ventricular morphology or surgical approach.     

Exercise Performance After Surgery for Pulmonary Atresia and Intact Ventricular Septum

The objective of this study was to assess exercise performance in subjects born in Sweden between 1980 and 1995 and undergoing surgery for pulmonary atresia and intact ventricular septum and to identify determinants of exercise performance. Twenty-seven subjects, 16 with biventricular repair and 11 with univentricular palliation, and 28 age- and sex-matched controls completed cardiopulmonary exercise and lung function testing. Peak oxygen uptake was determined using a symptom-limited ramp bicycle exercise protocol. Regression analysis was performed to identify predictors of peak oxygen uptake (V′O₂), The index group had lower peak V′O₂ (1.4 [median 0.8; range 2.5] l/min) than controls (1.9 [0.7; 3.1]; p < 0.05). Subjects without ventriculocoronary arterial communications (VCAC), corrected to biventricular circulation, had higher peak V′O₂, than the remaining index subjects. Decreased total lung capacity, low minute ventilation, and high physiologic dead space measured at peak exercise were all independent determinants of low peak V′O₂ Exercise capacity is generally decreased in subjects with pulmonary atresia and intact ventricular septum, although there are marked interindividual differences. Good exercise capacity was found in subjects without VCAC who had undergone biventricular repair. Decreased lung function was an unfavourable predictor of exercise capacity.     

Hospital therapy improves exercise tolerance and lung function in cystic fibrosis

We studied the benefits of in-hospital therapy on exercise capacity and related these changes to improvements in lung function in 17 patients with cystic fibrosis (CF) of moderate to extreme severity, as defined by results of pulmonary function tests performed at admission and discharge. Tolerance and adaptations to exercise were assessed from measures of peak work capacity (PWC), peak heart rate (PHR), and peak ventilation (PVE) obtained during an incremental exercise test. Treatment lasted from nine to 18 days. All measures of lung function improved; there also were significant increases in PWC, PHR, PVE, and PHR/PWC. Exercise-induced arterial desaturation was less at discharge than at admission. The PWC of the most severely affected patients remained abnormally low, and their adaptations to exercise were abnormal at discharge. We concluded that intensive in-hospital therapy will significantly improve exercise tolerance and lung function in patients with CF with moderate to severe pulmonary dysfunction.     

Cardiorespiratory response to exercise after the Fontan procedure for tricuspid atresia

Noninvasive exercise testing was used to assess gas exchange in 13 patients age 6-25 yr who had undergone Fontan procedures for tricuspid atresia, five of whom had preexisting Glenn shunts. The results were compared to 28 age- and sex-matched controls. Oxygen saturation was measured by ear oximetry at rest and after exercise. Ventilation, oxygen consumption (VO2), carbon dioxide production (VCO2), and heart rate were measured during progressive exercise. The ventilatory equivalents for oxygen (VE/VO2) and carbon dioxide (VE/VCO2), mixed expired pCO2 (PECO2) end-tidal pCO2 (PETCO2), and dead space to tidal volume ratio (VD/VT) were determined during steady state exercise on a cycle ergometer. Heart rate was higher for VO2 by 15% (p less than 0.02) and ventilation was higher for both VO2 (by 37%, p less than 0.001) and VCO2 (by 27%, p less than 0.002) in the patients than the controls. Mean VE/VO2 was 35.4 +/- 7.8 (SD) compared to 25.8 +/- 3.1 (p less than 0.001) and mean VE/VCO2 was 41.7 +/- 9.0 compared to 31.6 +/- 4.3 (p less than 0.001). Mean PECO2 was 21.4 +/- 4.4 torr with controls at 27.9 +/- 3.8 (p less than 0.001) and mean PETCO2 was 33.0 +/- 5.3 torr compared to 40.0 +/- 3.3 (p less than 0.001). The patients had a mean oxygen saturation of 92 +/- 5% at rest and abnormal saturation after exercise (87 +/- 9, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

鼻塞式呼吸机间歇指令通气联合肺表面活性物质治疗早产儿肺透明膜病的临床研究

目的 观察鼻塞式呼吸机间歇指令通气(NIMV)联合肺表面活性物质(PS)治疗早产儿肺透明膜病(NHMD)的临床疗效,并与常规机械通气及持续气道内正压通气(CPAP)的疗效进行比较.方法 NIMV组25例患肺透明膜病的早产儿经气管内滴入PS[100 mg/(kg·次)],然后拔管,予NIMV支持治疗,并与25例常规机械通气及24例CPAP的患儿进行比较,指标包括患儿的临床症状、体征、血气变化及并发症.结果 治疗后1 h,患儿症状体征明显好转;6、12及24 h,3组患儿的血气较治疗前显著改善,NIMV、常规机械通气及CPAP比较,差异无显著性(P＞0.05).但治疗过程中NIMV组的肺部感染及慢性肺疾病的发生率明显低于机械通气组[(8%vs 36%)、(20%vs 72%)],且NIMV组的反复呼吸暂停和二氧化碳潴留的发生率也明显低于常规CPAP组[(8%vs 36%)、(20%vs72%)].结论 应用NIMV治疗早产儿肺透明膜病既可减少或避免呼吸机相关性肺炎、慢性肺病等并发症,又可治疗早产儿常发生的反复呼吸暂停,避免二氧化碳潴留.     

Effect of Fontan Fenestration on Regional Venous Oxygen Saturation During Exercise: Further Insights Into Fontan Fenestration Closure

Fontan fenestration closure is a topic of great debate. The body of data regarding the risks and benefits of fenestration closure is limited yet growing. Previous studies have demonstrated that Fontan patients have less exercise capacity than those with normal cardiovascular anatomy. Differences also have been noted within various subgroups of Fontan patients such as whether Fontan is fenestrated or not. This study aimed to compare trends in regional oxygen saturations using near-infrared spectroscopy (NIRS) in patients with Fontan circulations during ramping exercise to further delineate differences between patients with and without a fenestration. It was hypothesized that Fontan patients with fenestrations have better exercise times, higher absolute regional oxygen venous saturations, and smaller arteriovenous differences than Fontan patients without fenestrations. For this study, 50 consecutive Fontan patients and 51 consecutive patients with normal cardiovascular anatomy were recruited. Placement of NIRS probes was performed to obtain regional oxygen saturations from the brain and the kidney. Readings were obtained at 1-min intervals during rest, exercise, and recovery. A standard Bruce protocol was used with a 5-min recovery period. Absolute regional tissue oxygenation values (rSO₂) and arterial-venous oxygen saturation differences (AVDO₂) calculated as arterial oxygen saturation (SPO₂)—rSO₂ for normal versus Fontan patients and for fenestrated versus unfenestrated Fontan patients were compared using independent t tests. When normal and Fontan patients were compared, the Fontan patients had a significantly shorter duration of exercise (9.3 vs 13.2 min; p < 0.001). No statistically significant difference in rSO₂ change or AVDO₂ was evident at the time of peak exercise, at 2 min into the recovery, or at 5 min into the recovery. A small oxygen debt also was paid back to the brain in the Fontan patients after exercise, as evidenced by a narrower AVDO₂ than at baseline. The comparison of Fontan patients with and without fenestration showed no statistically significant difference in exercise time, rSO₂ change, or AVDO₂. The Fontan patients were noted to have shorter exercise times than the normal patients and also appeared to have an alteration in postexertional regional blood flow. However, when the various Fontan subtypes were compared by presence or absence of a fenestration, no significant differences were noted with regard to change in regional oxygen saturation or arteriovenous oxygen saturation. Thus, for patients with Fontan physiology, closure of the fenestration does not seem to have an impact on the dynamics of regional oxygen extraction during exercise or recovery.     

Oxygen Pulse Kinetics in Fontan Patients During Treadmill Ramp Protocol Cardiopulmonary Exercise Testing

After single-ventricle palliation, patients have variable long-term functional outcomes. Cardiopulmonary exercise testing (CPET) is an assessment tool used to quantify functional outcome. Oxygen pulse kinetics during CPET, which can be an important indicator of dynamic changes in stroke volume reserve, has not been systematically studied in this population. This study aimed to analyze oxygen pulse kinetics during a treadmill ramp protocol among patients with Fontan physiology compared with that of normal subjects and to explore the ability of oxygen pulse kinetics to define functional status further. Peak oxygen pulse and change in oxygen pulse during ramp treadmill CPET were retrospectively collected and compared between 44 Fontan patients and 85 age- and sex-matched control subjects. The peak oxygen pulse was significantly lower in the Fontan group (9.80?±?4.11?ml/beat) than in the control group (13.62?±?4.7?ml/beat) (p????0.001). The resting oxygen pulse did not differ between the two groups (3.13?±?1.23 vs. 3.09?±?1.33?ml/beat; p?=?0.88). The oxygen pulse was higher in the patients with chronotropic insufficiency, but the difference was not statistically significant (11.11?±?4.97 vs. 9.25?±?3.63?ml/beat; p?=?0.17). Regression analysis showed a significant difference in the slope of the oxygen pulse-to-workload relationship. The Fontan group showed no relation between degree of reduction in the oxygen pulse from peak to end of exercise and the underlying defect, peak heart rate, peak oxygen consumption, ventilatory anaerobic threshold (VAT), expired volume (VE)/carbon dioxide output (VCO₂) at the VAT, maximum heart rate, or minimum oxygen saturation. Analysis of oxygen pulse kinetics in Fontan patients suggests that there is an early and progressive limitation in stroke volume compared with control subjects. This limitation may be partially masked by increased oxygen extraction. In patients with chronotropic insufficiency, absolute or body surface area-indexed oxygen pulse may be higher than in those with a normal heart rate response. A composite assessment of the oxygen pulse and oxygen pulse kinetics, including the oxygen pulse slope and the percentage of reduction in oxygen pulse from peak to end of exercise, may allow a more comprehensive assessment of the degree of cardiac limitation in this group of patients.     

Partial liquid ventilation versus conventional mechanical ventilation with high PEEP and moderate tidal volume in acute respiratory failure in piglets

This prospective randomized pilot study aimed to test the hypotheses that partial liquid ventilation combined with a high positive end-expiratory pressure (PEEP) and a moderate tidal volume results in improved gas exchange and lung mechanics without negative hemodynamic influences compared with conventional mechanical ventilation in acute lung injury in piglets. Acute lung injury was induced in 12 piglets weighing 9.0 +/- 2.4 kg by repeated i.v. injections of oleic acid and repeated lung lavages. Thereafter, the animals were randomly assigned either to partial liquid ventilation (n = 6) or conventional mechanical ventilation (n = 6) at a fractional concentration of inspired O(2) of 1.0, a PEEP of 1.2 kPa, a tidal volume < 10 mL/kg body weight (bw), a respiratory rate of 24 breaths/min, and an inspiratory/expiratory ratio of 1:2. Perfluorocarbon liquid 30 mL/kg bw was instilled into the endotracheal tube over 10 min followed by 5 mL/kg bw/h. Continuous monitoring included ECG, mean right atrial, pulmonary artery, pulmonary capillary, and arterial pressures, arterial blood gas, and partial pressure of end-tidal CO(2) measurements. When compared with control animals, partial liquid ventilation resulted in significantly better oxygenation with improved cardiac output and oxygen delivery. Dead space ventilation appeared to be lower during partial liquid ventilation compared with conventional mechanical ventilation. No significant differences were observed in airway pressures, pulmonary compliance, and airway resistance between both groups. The results of this pilot study suggest that partial liquid ventilation combined with high PEEP and moderate tidal volume improves oxygenation, dead space ventilation, cardiac output, and oxygen delivery compared with conventional mechanical ventilation in acute lung injury in piglets but has no significant influence on lung mechanics.     

Right ventricular performance and pulmonary haemodynamics in adolescent and adult patients with cystic fibrosis

A combined haemodynamic and radionuclide approach was used to evaluate right ventricular performance in 16 adolescent and adult patients with cystic fibrosis (CF). There were nine patients with mild arterial hypoxaemia (PaO₂>80% of predicted) and normal resting pulmonary artery pressure and seven patients with severe arterial hypoxaemia (PaO₂<70% of predicted) and resting pulmonary arterial hypertension (PH). The right ventricular ejection fraction (RVEF) by equilibrium angiocardiography using krypton 81^m as a tracer and stroke volume index (SVI) by thermodilution techniques were measured simultaneously and right ventricular end-diastolic and end-systolic volumes were derived. RVEF was normal in CF patients without PH (58.9±7.2%) but was reduced in those with PH (45.4±2.6%). There was a statistically significant inverse linear correlation between RVEF and afterload as assessed by mean pulmonary artery pressure and pulmonary vascular resistance (PVR: r=–0.78), indicating that RVEF ist afterload-dependent. Right ventricular function, however, as assessed by right ventricular end-systolic pressure-volume relations was even higher in CF patients with PH, indicating preserved or even increased right ventricular function in the face of an increased afterload stress.Abbreviations CF cystic fibrosis - PaO₂ arterial oxygen tension - PH pulmonary arterial hypertension - RVEF right ventricular ejection fraction - SVI stroke volume index - Pap pulmonary artery pressure - PVR pulmonary vascular resistance - COPD chronic obstructive pulmonary disease - VC vital capacity - FEV₁ forced expiratory volume in 1 s - RV resisdual volume - TLC total lung capicity - RVEDP right ventricular end-diastolic pressure - Pap_s systolic pulmonary artery pressure - Pap_d diastolic pulmonary artery pressure - PCWP pulmonary capillary wedge pressure - CO cardiac output - ED end-diastolic background-corrected counts - ES end-systolic background-corrected counts - CI cardiac index - RVEDVI right ventricular end-diastolic volume index - RVESVI right ventricular end-systolic volume index - P/V relation right ventricular end-systolic pressure/right ventricular end-systolic volume index - S-K score Shwachmann-Kulczycki score     

Changes in cerebral oxygenation and cerebral blood volume during endotracheal suctioning in ventilated neonates

The effect of endotracheal suctioning on cerebral haemodynamics was investigated in 29 newborn infants with a mean gestational age of 31 weeks (range 25-40 weeks). Prior to one of two suctioning procedures, the inspiratory fraction of oxygen was increased by 10%. Brain oxygenation and total haemoglobin concentration were estimated continuously by near infrared spectroscopy. Mean arterial blood pressure, arterial blood oxygen saturation and carbon dioxide tension were recorded simultaneously. Brain oxygenation decreased in parallel with arterial oxygen saturation during suctioning. Preoxygenation ameliorated the decrease in brain oxygenation and arterial oxygen saturation whereas there was no benefit with regard to the changes in total haemoglobin concentration, carbon dioxide tension or mean arterial pressure. Changes in total haemoglobin concentration were related closely to concomitant changes in carbon dioxide tension ( p < 0.0001) but unrelated to changes in mean arterial pressure or arterial oxygen saturation. Our findings suggest that cerebral blood volume may react to changes in carbon dioxide tension during endotracheal suctioning in mechanically ventilated neonates. Apparently, preoxygenation prior to suctioning does not ameliorate the stress in normoxic infants.     

Congenital Unilateral Pulmonary Venous Atresia: Definitive Diagnosis and Treatment

Three cases of unilateral right-sided pulmonary venous atresia were evaluated over an 18-year period. These bring the total number of cases to 25 in the literature. The clinical presentation of all these patients was similar and consisted of recurrent pulmonary infections, asthma-like symptoms, and exercise intolerance. The patients presented in 1982 (patient 1, a 12-year-old boy), 1994 (patient 2, a 9-year-old girl), and 1999 (patient 3, a 13-year-old boy). All patients were evaluated with a chest roentgenogram, and patients 1 and 2 had a ventilation and perfusion scan. Patients 1 and 3 also had cardiac catheterization and pulmonary angiography. Patient 2 had a magnetic resonance imaging study of the chest. Only patient 3 had wedge pulmonary angiography. Although a rare congenital defect, this diagnosis should be strongly suspected based on the typical clinical presentation and the preliminary studies, such as the chest roentgenogram and ventilation and perfusion scan. However, for definitive diagnosis, cardiac catheterization with wedge pulmonary angiography is necessary. Anastomosis of the atretic pulmonary veins to the left atrium is a theoretical consideration. However, this may not be feasible due to pulmonary venous anatomy or significant pulmonary dysfunction with pulmonary vascular changes. In these circumstances, we recommend performing pneumonectomy to remove the nidus for repeated bouts of pulmonary infections, to eliminate the left-to-right shunt, and to eliminate the dead space contributing to exercise intolerance.     

20例新生儿肺动脉高压的临床分析

新生儿动脉高压症２０例，均由超声心动图证实。其中原发性肺动脉高压３例；继发性肺动脉高压１７例，１２例继发于先天性心脏病，５例继发于围产期窒息、吸入性肺炎及湿肺。４例先天性心脏病的患儿用硫酸镁治疗，临床有效。治疗后动脉血氧饱和度和动脉化毛细血管法测定氧分压明显升高，二氧化碳分压降低，吸入氧浓度减少，没有发现明显的药物副作用。本组死亡６例，１４例存活者中２例自愈率，１例手术治愈，６例药物治愈，２例仍存     

Cerebral blood flow and metabolism during and after prolonged hypocapnia in newborn lambs

We studied the effects of prolonged (6 hours) hypocapnia and the abrupt termination thereof on cerebral blood flow and metabolism in six paralyzed, sedated (but not anesthetized) newborn lambs. Thirty minutes after institution of hyperventilation to an arterial carbon dioxide pressure of 15 +/- 2 torr, hyperventilation, cerebral blood flow had returned to baseline. Abrupt termination of hyperventilation after 6 hours resulted in a 110 +/- 71% increase in cerebral blood flow over baseline after 30 minutes of normocapnia. This cerebral hyperemia persisted for at least 90 minutes after hyperventilation was discontinued. Cerebral oxygen consumption did not change throughout the study. The posthypocapnia hyperemia noted in these animals after abrupt normalization of arterial carbon dioxide pressure may contribute to the increased risk of intracranial hemorrhage in newborn infants who are treated similarly in the management of pulmonary hypertension.     

Hypercapnia and hypocapnia in neonates

Background  The arterial partial pressure of carbon dioxide (PaCO₂) represents the balance between CO₂ production and consumption. Abnormal increase or decrease in PaCO₂ can affect the body’s internal environment and function. Permissive hypercapnia has aroused more attention as a novel ventilatory therapy. The aim of this study was to elucidate the effects of hypercapnia and hypocapnia on the functions of such neonatal organs as the lung and brain. Data sources  The PubMed database was searched with the keywords “hypocapnia”, “hypercapnia” and “newborn”. Results  Hypocapnia is a risk factor for potential damage to the central nervous system, such as periventricular leukomalacia, intraventricular hemorrhage, cerebral palsy, cognition developmental disorder, and auditory deficit. Hyperventilation can lessen pulmonary artery hypertension to certain extent, but hypocapnia can aggravate ischemia/reperfusion-induced acute lung injury. Severe hypercapnia can induce intracranial hemorrhage, even consciousness alterations, cataphora, and hyperspasmia. Permissive hypercapnia can improve lung injury caused by diseases of the respiratory system, lessen mechanical ventilation-associated lung injury, reduce the incidence of bronchopulmonary dysplasia and protect against ventilation-induced brain injury. In addition, permissive hypercapnia plays a role in expanding cerebral vessels and increasing cerebral blood flow. Conclusions  Severe hypercapnia and hypocapnia can cause neonatal brain injury and lung injury. Permissive hypercapnia can increase the survival of neonates with brain injury or respiratory system disease, and lessen the brain injury and lung injury caused by mechanical ventilation. However, the mechanism of permissive hypercapnia needs further exploration to confirm its safety and therapeutic utility.     

Regression of pulmonary arteriovenous malformations following heart transplantation

Pulmonary arteriovenous malformations (PAVMs) can occur following caval to pulmonary artery connection, Glenn and/or Fontan procedure, leading to severe cyanosis and exercise intolerance. It is unknown whether these abnormalities regress or persist following heart transplantation (HTx). Twenty patients with failed Fontan or Glenn procedures were screened for PAVMs prior to HTx by contrast echocardiography, selective pulmonary angiography, and pulmonary venous desaturation. Age at transplant, diagnosis, previous operations, time from Glenn to transplant, systemic oxygenation, hemoglobin level, and ventricular function were determined. The clinical course after HTx was characterized in three patients with significant PAVMs. Indications for HTx were exercise intolerance and severe cyanosis in one patient, and cyanosis and ventricular dysfunction in two. Pre-HTx, mean systemic saturation was 67%; mean pulmonary venous wedge saturation was 81%. Post-HTx, oxygen saturations were normal (> 96%) at 14, 40, and 180 days. Contrast echocardiography, performed 1 month to 3.3 yrs after HTx, showed no intrapulmonary shunting in two patients and minimal shunting in one. One patient suffered an embolic stroke from right-to-left shunting post-HTx. All patients are alive and well 35, 71, and 73 months post-HTx. In patients with single ventricle physiology, PAVMs are not an absolute contraindication to HTx. Heart-lung transplant may not be required for these patients.     

腹腔镜幽门肌切开术CO2气腹对呼吸循环及血气分析指标的影响

目的 探讨腹腔镜幽门肌切开术CO2气腹对患儿呼吸循环及血气分析指标的影响.方法 监测20例腹腔镜下幽门环肌切开术患儿呼吸循环及血气分析指标.结果 气腹后10 min、20 min潮气量(VT)明显降低,亦明显低于撤销气腹后5 min值,差异均有统计学意义(P＜0.05);气腹后10 min、20 min呼气末CO2值(PetCO2)明显增高,与气腹前相比差异有统计学意义(P＜0.05),撤销气腹后5 min PetCO2值略有下降,与气腹前相比差异有统计学意义(P＜O.05).气腹后收缩压(DBP)、舒张压(SBP)、平均动脉压(MAP)、血氧饱和度(SpO2)、心率(HP)、气道压(Peak)、肺顺应性(CL)各值均有改变,与术前比较差异无统计学意义.结论 小婴儿腹腔镜手术中,CO2气腹主要可引起VT、PetCO2的改变,只要术中完善呼吸和循环系统的监测,并采取相应措施,小婴儿腹腔镜手术和麻醉是安全可行的.     

Exertional Oscillatory Ventilation During Cardiopulmonary Exercise Test in Fontan Patients with Total Cavopulmonary Connection

Exertional oscillatory ventilation (EOV) has been noted during cardiopulmonary exercise testing (CPX) in patients with heart failure. EOV is a predictor of poor prognosis in adult patients with heart failure. The objective of this study was to clarify the incidence and influence of EOV in Fontan patients. Symptom-limited CPX was performed in 36 Fontan patients at 12.3 ± 4.3 (6.5–24.4) years of age or 5.9 ± 2.0 (3.0–11.2) years after total cavopulmonary connection (TCPC). Mean age at the time of TCPC was 6.3 ± 3.3. All 36 TCPC patients were classified as New York Heart Association classification I or II. They also underwent cardiac catheterization subsequently. EOV was defined as cyclic fluctuations in minute ventilation at rest that persist during effort lasting ≥60% of the exercise duration, with an amplitude ≥15% of the average resting value. EOV was noted in 21 of 36 Fontan patients (58%) with good clinical status. Univariable analysis between Fontan patients with and those without EOV showed significant differences in age at TCPC (p < 0.05), age at CPX (p < 0.02), weight at CPX (p < 0.02), follow-up duration between TCPC and CPX (p < 0.04), ventricular morphology (p < 0.05), and metabolic equivalents (p < 0.05) and peak minute oxygen uptake (VO₂) per body weight (p < 0.05). Multivariable analysis showed that EOV was significantly related to peak VO₂ per kilogram. In conclusion, EOV was frequently noted during exercise in Fontan patients with good clinical status. EOV during exercise seems to be related to higher peak VO₂ per kilogram and younger age at TCPC, which is a contrary result to those for adult patients with chronic heart failure. EOV is a remarkable phenomenon during exercise to compensate for impaired cardiopulmonary function in Fontan patients.     

Diffusing capacity for carbon monoxide (T(LCO)) and oxygen saturation during exercise in patients with cystic fibrosis]

OBJECTIVES:To estimate the value of diffusing capacity for carbon monoxide (T(LCO)) in patients with cystic fibrosis and to evaluate its ability to predict arterial desaturation during exercise. METHOD: Fourty-four patients (9-30 years) with cystic fibrosis performed pulmonary function tests with measure of T(LCO) and a bicycle incremental exercise test. They represent a wide variation in disease severity: mean Shwachman score: 77.8 (range: 40-100), mean FEV1%: 72.8 (range: 17-131). This study investigated the relationship between T(LCO), lung volumes and exercise data. RESULTS: T(LCO) remained normal for a long time in patients with cystic fibrosis: 82% of them show a normal T(LCO) (mean value: 91.3% of predicted). T(LCO) was significantly correlated with FEV(1), residual volume, maximal work load and maximum oxygen uptake. A fall in arterial oxygen saturation was uncommon in our study (five patients) and not significantly correlated with T(LCO). CONCLUSIONS: T(LCO) is a good criter of severity of cystic fibrosis but remains unreliable to predict values above which physical activity is safe, without arterial desaturation. Exercise tests should be proposed in order to evaluate exercise adaptation of each patient and determine which factor limits maximal performance.