Respiratory Changes After Open-heart Surgery

Extubation in the Operating Room After Fontan Procedure: Does It Make a Difference?

Early extubation appears to have beneficial effects on the Fontan circulation. The goal of this study was to assess the impact of extubation on the operating table in comparison with extubation during the first hours after Fontan operation (FO) on the early postoperative course. Between 2013 and 2016, 114 children with a single ventricle heart malformations (mean age, 3.8 ± 2.3 years) underwent FO: 60 patients were extubated in the operating room (ORE) and 54 in the intensive care unit (ICUE) in the median time of 195 min (range 30-515 min) after procedure. Pre-, peri-, and postoperative records were retrospectively analyzed. The hospital survival rate was 100%. One patient from the ORE group needed an immediate reintubation because of laryngospasm. The ORE group showed lower heart rate (106.5 vs. 120.3 bpm; p < 0.001) and lower central venous pressure (10.4 vs. 11.4 mmHg; p = 0.001) than patients in the ICUE group within the first 24 h after FO, as well as higher systolic blood pressure within 7 h after operation (88.6 ± 2.5 vs. 85.6 ± 2.6 mmHg; p = 0.036). The ORE children manifested significantly less pleural effusions during 48 h after FO (38.0 vs. 49.5 ml/kg; p = 0.004), received less intravenous fluid administration within 24 h after FO (54.1 vs. 73.8 ml/kg; p = 0.019), less inotropic support (9.8 vs. 12.8 h of dopamine; p = 0.033), and less antibiotics (4.7 vs. 5.8 days; p = 0.037). ICUE children manifested metabolic acidosis more frequently than the ORE group 3-4 h after FO (p < 0.05). Immediate extubation after FO in comparison with extubation in the ICU appears to be associated with improved hemodynamics and reduced application of therapeutic interventions in the postoperative course.

Ventilatory dependency after cardiovascular surgery

OBJECTIVES

Ventilatory dependency is a widely recognized complication of cardiovascular surgery, often leading to tracheostomy. Some risk factors for its occurrence have been documented. Less well characterized are short- and long-term outcomes. Therefore, objectives were to identify risk factors for ventilatory dependency, assess its short- and long-term outcomes, and determine impact of tracheostomy.

METHODS

From January 1998 to September 2001, 12,777 patients underwent cardiovascular surgery and survived at least 72 hours. Of these patients, 704 (5.5%) developed ventilatory dependency (cumulative intubation >72 hours); 185 (26%) underwent tracheostomy. Preoperative, intraoperative, and intensive care unit admission data were used sequentially to understand predictors of ventilatory dependency. Outcomes were analyzed by time-related methods, and impact of tracheostomy was assessed using competing-risks analysis.

RESULTS

Hemodynamic status on intensive care unit admission (low cardiac output, vasopressor use, pulmonary hypertension; P < .0001) and early postoperative events (stroke, bacteremia; P < .0001) were more important than preoperative and intraoperative variables in predicting ventilatory dependency. Survival at 30 days, 1 year, and 5 years thereafter was 76%, 49%, and 33% and was strongly associated with favorable hemodynamic status. By 28 days, 24% of patients received tracheostomy; survival at 30 days and 2 years thereafter was 74% and 26%, considerably below anticipated survivals of 84% and 58%.

CONCLUSIONS

Improved operative and postoperative strategies to preserve myocardial function and restore hemodynamics should decrease the prevalence of ventilatory dependency. Unfortunately, preoperative models of ventilatory dependency are too insensitive for clinical use. Tracheostomy and its outcome are also poorly predicted, highlighting the complex interaction of events altering patients' conditions before and after tracheostomy.

Effects of long intubation period on respiratory functions following open heart surgery

The objective of the present study was to compare pre- and postoperative pulmonary function tests in adult patients who had intubation periods greater and less than 24 hours following elective open heart surgery. Group 1 consisted of 91 patients (18 females and 73 males) gr, whose intubation periods were more than 24 hours (mean: 8.1+/-18.6 hours); and group 2 75 patients (13 females and 62 males) who had intubation periods less than 24 hours (mean: 13.25+/-3.60 hours). The pulmonary function test measurements were obtained from a vitalograph before and after the operation (just before being discharged from the hospital), All patients underwent cardiopulmonary physiotherapy and a rehabilitation programme during their hospital stay. The patients were similar in height and weight. The duration of hospitalization of the patients who had a prolonged intubation period was 17.26+/-9.7 days, while that of the control group was 10.64+/-2.04 days (P<0.0001). When the preoperative pulmonary function test values of each patient were compared with the expected values, the percent values of forced expiratory volume for one second, flow velocity of the mid-forced expiration and forced expiratory flow which were achieved by group 2 were significantly high compared to those of group 1 (P=0.014, P= 0.03 and P<0.0001, respectively). However, the percent values of forced vital capacity were similar. When the percent variations of the differences between the pre- and postoperative pulmonary function test values of the groups were compared, all values except the flow velocity of the mid-forced expiration, and forced vital capacity, were found to be significantly lower statistically in the group having a prolonged intubation period. As a result, it was determined that the patients whose preoperative pulmonary function test values were poor, had longer intubation periods and similarly, they continued to be worse after the operation. We believe that it is advantageous to apply more intensive pulmonary rehabilitation for prolonged periods to these patients in the postoperative period.

Effects of minor surgery and endotracheal intubation on postoperative breathing patterns in patients anaesthetized with isoflurane or sevoflurane

We studied the effects of minor surgery and endotracheal intubation on postoperative breathing patterns. We measured breathing patterns and laryngeal resistance during the periods immediately before intubation (preoperative) and immediately after extubation following minor surgery (postoperative) in eight patients anaesthetized with sevoflurane and eight patients anaesthetized with isoflurane, breathing spontaneously through a laryngeal mask airway at a constant end-tidal anaesthetic concentration (1.0 MAC). In both sevoflurane-anaesthetized and isoflurane-anaesthetized patients, expiratory time was reduced and inspiratory and expiratory laryngeal resistance increased after surgery. In sevoflurane-anaesthetized patients, occlusion pressure (P0.1) increased without changes in inspiratory time (T(I)). Occlusion pressure did not change and T(I) was greater in isoflurane-anaesthetized patients after surgery. Minor surgery may have a small but significant influence on breathing and increased laryngeal resistance following endotracheal intubation may modulate these changes. The difference in breathing pattern between sevoflurane and isoflurane may be a result of different responses of the central nervous system to different anaesthetics in the presence of increased laryngeal resistance.

Estudo da função pulmonar em pacientes submetidos a revascularização do miocárdio sem circulação extracorpórea com derivação intraluminal

As alterações da função pulmonar nos pacientes submetidos a cirurgias com auxílio da Circulação Extracorpórea (CEC) têm sido relatadas na literatura. O objetivo do presente estudo foi analisar a função pulmonar de um grupo de pacientes submetidos a cirurgia de revascularização do miocárdio sem o uso da CEC. Foram estudados de maneira prospectiva 23 pacientes portadores de insuficiência coronariana e submetidos a cirurgia de revascularização do miocárdio sem CEC. A idade variou de 36 a 69 anos, sendo 16 pacientes do sexo masculino e sete do sexo feminino. A avaliação da função pulmonar foi feita através de espirometria e prova alvéolo-respiratória, realizadas no período pré-operatório, no quarto dia (PO4) e no décimo dia (PO10> pós-operatório. A análise dos dados revelou redução da Capacidade Vital (CV) em 37,84% (p<0,01) no PO4 em comparação aos valores pré-operatórios, persistindo esta redução no PO10 porém em menor magnitude 26,85% (p<0,01). A Capacidade Vital Forçada (CVF) também apresentou diminuição no PO4 em média ± 38,37% (p<0,01) em relação aos valores de pré e no PO10 houve melhora, permanecendo diminuição de 28,80% (p<0,01). O Volume Expiratório Forçado no primeiro segundo (VEF1 e o Fluxo Expiratório Forçado entre 25 e 75% da CVF (FEF25-75) estiveram diminuídos no P0(4) em 36,88% (p<0,01) e 30,47% (p<0,01) respectivamente e no PO10 havia diminuição de 29,29% (p<0,01) para o VEF1, e 27,61 % (p<0,01) para o FEF25-75. As relações VEF1/CVF e FEF25-75/CVF não mostraram alterações significantes. A Ventilação Voluntária Máxima (VVM) mostrou-se diminuída no PO4 em média de 37,4% (p<0,0l) em relação ao pré e no PO10 26,22% (p<0,0l). A Gasometria em ar ambiente mostrou haver redução da pressão parcial do Oxigênio (PaO2) no PO4 em média de 12,92% (p<0,01), permanecendo até o PO10 a média de 10,80% (p<0,01) de redução em relação ao pré. A pressão parcial do Gás Carbônico (PaCO2) apresentou redução média de 5,22% (p<0,05) no PO4 e havia ainda redução no PO10 em média de 0,51 % (não significante). O cálculo do "shunt" (Q,/Q) mostrou haver aumento em média de 69,03% (p<0,0l) no PO4 e de 58,73% (p<0,0l) no PO10. Concluiu-se que todos os pacientes apresentaram no PO4 diminuição dos valores obtidos na espirometria (CV, CVF, VEF1 FEF25-75 ,VVM) e nas medidas dos gases (PaO2 e PaCO2 e aumento do "shunt" calculado. No PO10 houve recuperação da CV, CVF, VEFI, VVM e PaCO2. No PO10 em relação ao pré-operatório persistiam ainda alterações da CY, CVF, VEF1, FEF25-75, VVM, PaO2 e "shunt".

Early extubation of the trachea after repair of secundum-type atrial septal defects in children

To investigate the role of anaesthetic management in early extubation of the trachea in children after closure of a secundum-type atrial septal defect (ASD II), a retrospective chart review for a two-year period was performed. We identified 36 children who underwent surgical repair of an isolated ASD II. In 19 children (53%) the tracheas were extubated in the operating room immediately after surgery and in 17 patients (47%) the tracheas remained intubated and the lungs were ventilated in the Intensive Care Unit. There was no difference in age (69.5 +/- 33.8 vs 72.9 +/- 45.0 mo) or weight (19.5 +/- 8.1 versus 20.5 +/- 12.7 kg) between the two groups (mean +/- SD). Children in the extubated group had a shorter duration of cardiopulmonary bypass (43.4 +/- 7.8 min) than those remaining intubated (31.7 +/- 12.7 min) (P < 0.05). The children whose tracheas were extubated early received a lower perioperative fentanyl dose (5.9 +/- 6.4 micrograms.kg-1) than those remaining intubated (35.1 +/- 8.5 micrograms.kg-1). Those children in the extubated group had a lower hourly requirement for morphine by infusion (13.6 +/- 5.7 vs 18.2 +/- 5.4 micrograms.kg-1.hr-1) and a shorter stay (20.5 +/- 3.7 versus 29.0 +/- 11.2 hr) in the Intensive Care Unit. Re-intubation of the trachea was not required in any of the children and no deaths occurred. Early extubation after ASD II repair is safe and, given the results of this study, may offer certain advantages over prolonged intubation and ventilation in these children.

Does the anesthetic method influence the postoperative breathing pattern and gas exchange in hip surgery? A comparison between general and spinal anesthesia

We studied the effects of elective hip surgery, performed under either spinal (SA, n = 10) or general anesthesia (GA, n = 10), on breathing pattern and gas exchange. Measurements were made with respiratory inductive plethysmograph and indirect calorimetry in two positions before and after surgery. The method of anesthesia had no effect on the severity of postoperative hypoxemia. Reduced arterial oxygenation (PaO2; P less than 0.001, SA from 12.5 +/- 2.37 kPa to 10.5 +/- 1.38 kPa, GA from 12.5 +/- 2.95 kPa to 10.5 +/- 1.75 kPa) despite increased alveolar ventilation (P less than 0.01; from 2.30 +/- 0.37 l/min to 2.39 +/- 0.43 l/min in SA, 2.27 +/- 0.56 l/min to 2.57 +/- 0.35 l/min in GA) and reduced arterial carbon dioxide partial pressure (PaCO2; SA from 5.20 +/- 0.22 kPa to 4.95 +/- 0.33 kPa, P less than 0.01, GA from 5.07 +/- 0.36 kPa to 4.72 +/- 0.41 kPa, P less than 0.05) indicated maldistribution of ventilation and perfusion. Changes in breathing pattern and gas exchange and differences between the groups were minimal. Minute ventilation, tidal volume and mean inspiratory flow remained unchanged in both groups. The contribution of rib cage to tidal volume increased postoperatively in the supine position (P less than 0.001; SA from 32.6% +/- 10.3 to 46.3% +/- 7.5, GA from 36.5 +/- 16.4 to 48.5% +/- 15.4). CO2 production, oxygen consumption and energy expenditure remained unchanged. The postoperative changes in breathing pattern are related to the operation, not to the type of anesthesia and do not explain the alterations in gas exchange.

Respiratory changes after open-heart surgery

Breathing pattern was studied non-invasively in 20 coronary artery bypass surgery patients before the operation and post-operatively after weaning from mechanical ventilation. Post-operatively minute ventilation (VE), breathing frequency (Fr) and mean inspiratory flow (VT/TI) increased (28%, 42%, 27%; p less than 0.01, p less than 0.001, p less than 0.01, respectively), while tidal volume (VT) decreased (15%, p less than 0.025). CO2 production (VCO2) and oxygen consumption (VO2) increased postoperatively (p less than 0.001 for both), contributing to the increase in ventilatory demand. Reduced variation of VT and Fr (p less than 0.001, p less than 0.01, respectively) and number of sighs (p less than 0.001) were characteristic of the post-operative breathing pattern. Post-operatively an increase in the contribution of rib cage (%RC) to tidal volume in the supine position was observed suggesting reduced motion of the diaphragm. All patients had atelectasis, 17 had pleural fluid and only 6 normal vascularity post-operatively. The shallow breathing in combination with increased ventilatory demand, impaired gas exchange and the surgical trauma of the thorax predispose to postoperative respiratory complications.

Current management of patients after cardiopulmonary bypass

The postoperative management of cardiac surgical patients is reviewed with particular reference to some of the recent advances and current controversies. It is emphasised that there has been a marked decrease in the incidence of many of the major problems associated with cardiopulmonary bypass and that, in the majority of cases, cardiac surgery is now a routine procedure associated with a very low morbidity and mortality.

Pre- and postoperative pulmonary function abnormalities in coronary artery revascularization surgery

Pulmonary function studies were conducted one to two days prior to, two weeks after, and an average of 116 days after coronary artery revascularization surgery. Preoperation it was found that 11 of 19 patients had mild to moderate obstruction, 8 of 17 had diffusing capacity less than 80 percent of predicted, and 9 of 17 had mild hypoxemia. Many of these abnormalities seemed related to smoking. After surgery, significant reductions in volumes, diffusion and PaO2 were found at two weeks. By the last study, there was improvement in volumes and diffusion, but they remained significantly reduced in comparison to preoperative levels. Arterial oxygen tension (PaO2) had returned to preoperative levels. Correction of diffusion for volume showed there to be no change in any of the study periods suggesting chest wall alteration is a major component of the abnormality. It is concluded that close monitoring of pulmonary function is indicated before and after operation in this patient population even if the patient is asymptomatic.