Early effects of the ex vivo evaluation system on graft function after swine lung transplantation

Objectives:Ex vivo lung evaluation (ex vivo) has been developed as a useful method by which to assess lungs from donation-after-cardiac death (DCD) donors prior to transplant. However, the safety of the ex vivo circulation itself with respect to grafts has not been fully investigated. The aim of this study is to evaluate the effects of the ex vivo circuit using a swine lung transplant model. Methods: Lungs with or without 2-h warm ischemia were used. To assess post-transplant graft function, the left lung was transplanted after 2-h ex vivo or cold preservation; blood gas analysis of the left pulmonary vein (partial pressure of oxygen, PO₂) was performed during the 6-h post-transplant follow-up period. Data were compared between the ex vivo (+) and ex vivo (−) groups. Results: Partial pressure of oxygen/ inspired oxygen fraction (PO₂/FiO₂) in the ex vivo (−) group was significantly greater than that in the ex vivo (+) group until 3 h after transplant. The PO₂/FiO₂ levels in both groups then increased and became similar at 6 h after transplant, regardless of whether ischemic or non-ischemic lungs (p < 0.001 and p = 0.004, respectively) were used. Conclusions: Negative effects of the ex vivo system were limited and seen only in the immediate post-transplant period. Therefore, in DCD swine lung transplantation, the ex vivo system appears to be safe.     

Utility of transesophageal echocardiography and pulmonary artery catheterization during laparoscopic assisted abdominal aortic aneurysm repair

Background: Advanced laparoscopic procedures are more commonly performed in elderly patients with cardiac disease. There has been limited data on the use of pulmonary artery catheters (PAC) and transesophageal echocardiography (TEE) to monitor hemodynamic changes. Methods: We prospectively studied eight patients undergoing laparoscopic assisted abdominal aortic aneurysm repair. All patients had a PAC and all but one had an intraoperative TEE. Data included heart rate (HR), temperature (temp), pulmonary artery systolic (PAS) and diastolic (PAD) pressures, mean arterial pressure (MAP), central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), mixed venous oxygen saturation (MVO₂), and oxygen extraction ratio (O₂Ex) and was obtained prior to induction, during insufflation, after desufflation, during aortic cross-clamp, and at the end of the procedure. End diastolic area (EDA), a reflection of volume status, was measured on TEE. ANOVA was used for data analysis. Results: No changes were noted in HR, temp, PAS, PCWP, CI, MVO₂, and O₂Ex. PAD and CVP were greater during insufflation compared with baseline and aortic cross-clamp without associated changes in EDA. MAP was higher at baseline compared with all other times during the procedure. Conclusions: Insufflation increased PAD and CVP. However, volume status as suggested by EDA and PCWP did not change. These data question the reliability of hemodynamic measurements obtained from the PAC during pneumoperitoneum and suggest that TEE may be sufficient for evaluation of volume status along with the added benefit of timely detection of ventricular wall motion abnormalities. Received: 27 March 1997/Accepted: 5 July 1997     

Relationship between plasma neutrophil elastase and respiratory index of patients who had undergone cardiac surgery with cardiopulmonary bypass

To evaluate the effects of cardiopulmonary bypass (CPB) on the release of polymorphonuclear leukocyte elastase (PMN-E) and postoperative pulmonary function, the perioperative plasma levels of PMN-E in α₁-antitrypsin complex (EAC) and hydrogen peroxide concentration in the expired breath were measured in eight patients who underwent cardiac surgery with CPB, and the relationship between EAC levels and the respiratory index (RI) was studied. Although PMN, EAC, and the ratio of EAC to neutrophil (E/N) were elevated significantly after surgery, alveolar-arterial oxygen difference (A-aDO₂) and respiratory index (A-aDO₂/PaO₂) did not change when compared with those of the preoperative period. Hydrogen peroxide concentration in the expired breath also did not change (below 2.5 μmol·l⁻¹) during the perioperative period. These results suggest that the elevation of EAC immediately after cardiac surgery using CPB, which lasted less than 2h, was not a cause of postoperative pulmonary disorder. However, there was a significant positive correlation between E/N ratio and respiratory index (r=0.67,P<0.01). Thus excessive release of PMN-E during CPB may be implicated in the etiology of postoperative respiratory dysfunction. Part of this work was presented at the 41st annual meeting of the Japan Society of Anesthesiology, Tokyo, April 14, 1994     

Effect of inspired oxygen on the cardiovascular effects of protamine after cardiopulmonary bypass

We have performed a randomized prospective study of the effects of inspired oxygen fraction (FIO2) on the haemodynamic changes after protamine infusion. Thirty-four patients undergoing first time coronary artery bypass surgery were allocated randomly to receive either an FIO2 of 1.0 (group O) or 0.35 (group A) after cardiopulmonary bypass. Before and after infusion of protamine, haemodynamic measurements were obtained, including mean arterial pressure (MAP), mean pulmonary artery pressure, central venous pressure, pulmonary capillary wedge pressure (PCWP), cardiac index (CI), pulmonary vascular resistance index (PVRI) and systemic vascular resistance index (SVRI). In group O, there were increases in mean MAP (8%), PVRI (48%) and SVRI (18%), and decreases in mean CI (10%) and PCWP (15%). Group A showed changes of 0%, -8%, -6%, +3% and +32%, respectively. We found a significant difference between groups in changes in PVRI (P < 0.0001), SVRI (P < 0.01), CI (P < 0.05) and PCWP (P < 0.001). During infusion of protamine, 31% of patients in group O and 6% of patients in group A had a decrease in systolic arterial pressure to less than 80 mm Hg (ns, chi-square test). These observations suggest that FIO2 alters the haemodynamic effects of protamine.      

The effects of pre-operative dexmedetomidine infusion on hemodynamics in patients with pulmonary hypertension undergoing mitral valve replacement surgery

BACKGROUND: The aim of this study was to investigate the effects of pre-operative dexmedetomidine infusion on hemodynamics in patients with pulmonary hypertension undergoing mitral valve replacement surgery. METHODS: Patients were randomly divided into placebo (group P, n= 16) and dexmedetomidine (group D, n= 16) groups. In group D, a 1 microg/kg bolus dose of dexmedetomidine was administered 10 min before the induction of anesthesia, followed by a 0.4 microg/kg/h infusion until the surgical incision. Anesthesia was induced with lidocaine (1 mg/kg), midazolam (0.2 mg/kg) and fentanyl (5 microg/kg) in both groups. Anesthesia was maintained with 0.5% isoflurane and fentanyl depending on the hemodynamic situation. The hemodynamic values during the investigation were obtained. RESULTS: In group D, the mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP) and pulmonary capillary wedge pressure (PCWP) were decreased effectively in comparison with the values in the placebo group (P < 0.05), and there was an attenuation in the increase in the systemic vascular resistance index (SVRI) and pulmonary vascular resistance index (PVRI) at the post-sternotomy period. CONCLUSIONS: The pre-operative administration of the alpha(2)-agonist dexmedetomidine decreases the fentanyl requirement and attenuates the increase in SVRI and PVRI at the post-sternotomy period relative to the baseline levels, and decreases effectively MAP, MPAP and PCWP in comparison with the values in the placebo group, in patients with pulmonary hypertension undergoing mitral valve replacement surgery.     

A Meta‐Analysis of Pulmonary Function With Pulsatile Perfusion in Cardiac Surgery

The aim of this study was to determine whether pulsatile or nonpulsatile perfusion had a greater effect on pulmonary dysfunction in randomized controlled trials. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were used to identify available articles published before April 13, 2013. A meta‐analysis was conducted on the effects of pulsatile perfusion on postoperative pulmonary function, intubation time, and the lengths of intensive care unit (ICU) and hospital stays. Eight studies involving 474 patients who received pulsatile perfusion and 496 patients who received nonpulsatile perfusion during cardiopulmonary bypass (CPB) were considered in the meta‐analysis. Patients receiving pulsatile perfusion had a significantly greater PaO₂/FiO₂ ratio 24 h and 48 h post‐operation (P < 0.00001, both) and significantly lower chest radiograph scores at 24 h and 48 h post‐operation (P < 0.00001 and P = 0.001, respectively) compared with patients receiving nonpulsatile perfusion. The incidence of noninvasive ventilation for acute respiratory insufficiency was significantly lower (P < 0.00001), and intubation time and ICU and hospital stays were shorter (P = 0.004, P < 0.00001, and P < 0.00001, respectively) in patients receiving pulsatile perfusion during CPB compared with patients receiving nonpulsatile perfusion. In conclusion, our meta‐analysis suggests that the use of pulsatile flow during CPB results in better postoperative pulmonary function and shorter ICU and hospital stays.     

Increased B-type natriuretic peptide during liver transplantation: relationship to invasively measured hemodynamic parameters

Background

The role of B-type natriuretic peptide (BNP) concentration in predicting cardiac dysfunction has been extensively investigated in many clinical conditions. Little is known, however, about its relationships with hemodynamic parameters from right heart catheterization in patients undergoing liver transplant surgery.

Methods

We retrospectively evaluated 525 patients who underwent liver transplantation. Hemodynamic variables from a Swan-Ganz catheter and BNP concentrations were measured 1 hour after induction of general anesthesia. Patients were stratified by quintiles of BNP concentrations. Univariate and multivariate logistic regression analysis were used to identify hemodynamic parameters associated with BNP ≥ 135 pg/mL, a cutoff point for the 5th quintile.

Results

Univariate analysis showed that factors significantly associated with BNP ≥ 135 pg/mL included model for end-stage liver disease (MELD) score, diastolic blood pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure (PCWP), cardiac index, right ventricular end-diastolic volume index (RVEDVI), systemic vascular resistance index, pulmonary vascular resistance index (PVRI), and right ventricular stroke work index. Multivariate analysis revealed that MELD score (odds ratio [OR] = 1.059, P < .001), PCWP (OR = 1.116, P = .026), RVEDVI (OR = 1.010, P = .009), and PVRI (OR = 1.009, P = .002) were independent determinants of BNP ≥ 135 pg/mL.

Conclusions

Severity of liver disease, preload dependent hemodynamic parameters, and pulmonary vascular resistance were found to be significantly associated with increased BNP concentration, reinforcing the utility of BNP as a marker of cardiac strain and ventricular volume overload in liver failure patients undergoing liver transplant surgery.     

Intra-aortic balloon pump induced pulsatile perfusion reduces endothelial activation and inflammatory response following cardiopulmonary bypass

Objective: Intra-aortic balloon pump (IABP)-induced pulsatile perfusion has demonstrated that it can preserve organ function during cardiopulmonary bypass (CPB). We evaluated the role of IABP pulsatile perfusion on endothelial response. Methods: Forty consecutive isolated CABG undergoing preoperative IABP were randomized to receive IABP pulsatile CPB during aortic cross-clamping (group A, 20 patients) or standard linear CPB (group B, 20 patients) during cross-clamp time. Hemodynamic results were analyzed by Swan-Ganz catheter [mean arterial pressure (MAP), cardiac index (CI), indexed systemic vascular resistances (ISVR), indexed pulmonary vascular resistances (IPVR), wedge pressure (PCWP)]. Inflammatory/endothelial response was analyzed by pro-inflammatory (IL-2, IL-6, IL-8), anti-inflammatory cytokines (IL-10), and endothelial markers [vascular endothelial growth factor (VEGF) and monocyte chemotactic protein-1 (MCP-1)]. All measurements were recorded preoperatively (T0), before aortic declamping (T1), at the end of surgery (T2), 12 h (T3) and 24 h (T4) postoperatively. ANOVA for repeated measures was used to evaluate the differences of means. Results: Hemodynamic response was comparable except for higher MAP (p = 0.01 at T1) and lower ISVR (p = 0.001 at T1, p = 0.003 at T2) in group A. No differences were found in perioperative leakage of IL-2, IL-6, and IL-8 between the two groups (within-group p = 0.0001 either in group A and group B; between-groups p = NS at 2-ANOVA). Group A showed significantly lower VEGF (between-groups p = 0.001 at 2-ANOVA, p = 0.001 at T1, T2) and MCP-1 (between-groups p = 0.001 at 2-ANOVA, p = 0.001 at T1, T2) with higher IL-10 secretion (between-groups p = 0.001 at 2-ANOVA, p = 0.01 at T1, T2, T3). Conclusions: IABP-induced pulsatile perfusion allows lower endothelial activation during CPB and higher anti-inflammatory cytokines secretion.     

Superoxide generation during cardiopulmonary bypass: Is there a role for vitamin E?

The cytotoxic metabolites of oxygen [superoxide (O₂⁻), hydrogen peroxide (H₂O₂), and hydroxyl (OH^•)] have been demonstrated to be involved in the peroxidation of membrane lipids consequently altering membrane composition, morphology, and function. Of all the lines of defense adopted by living organisms against toxic oxygen free radicals, vitamin E is most effective in the prevention of membrane damage. Cardiopulmonary bypass (CPB) has been shown to activate complement and cause sequestration of leukocytes which can recruit, adhere, and stimulate release of cytotoxic oxygen radicals. A prospective study of 30 patients evaluated the effects of CPB with and without an exogenous free radical scavenger (Group I, N = 20, control) and (Group II, N = 10, vitamin E) on H₂O₂ (a marker of oxygen free radicals) malonaldehyde (a marker of lipid peroxidation), transpulmonary leukosequestration, and plasma levels of vitamins E and C. Group I showed a progressive increase in H₂O₂ during CPB from 65 ± 6 to 130 ± 11 μm/ml (P < 0.0001); plasma vitamin E decreased from 15 ± 3 to 6 ± 1 mg/liter (P < 0.0001) while vitamin C increased from 1.6 ±.3 to 2.3 ±.3 mg/dl (P < 0.0001). Group II showed no significant increase in H₂O₂ (from 78 ± 8 to 93 ± 5 μm/ml) during CPB and a significant reduction in H₂O₂ levels compared to Group I (P < 0.001); plasma vitamins E and C did not change significantly in Group II. Transpulmonary leukosequestration, expressed as median cell difference (MCD), occurred in Group I (MCD = 1700) and Group II (MCD = 1900) (P < 0.001 vs pre-CPB). We conclude that (1) cytotoxic oxygen radicals liberated during CPB can be reduced by pretreatment with vitamin E despite complement activation and pulmonary sequestration of white blood cells. (2) Vitamin E pretreatment prevented a clinically overt vitamin E deficiency during CPB. (3) The rise in vitamin C post-CPB demonstrates the direct effect on oxidized vitamin E by vitamin C in vivo.     

以氧供为导向的血流动力学麻醉管理模式对原位肝移植术中肺功能的影响

目的研究以保证氧供为指标的血流动力学麻醉管理模式对肝移植术中肺功能的影响.方法以目标氧供600～1000ml/min为指标对40例肝移植患者实施术中管理.分别于全麻诱导后（T0）、无肝期前5 min（T1）、门静脉阻断时（T2）、阻断后30 min（T3）、60 min（T4）、新肝期10 min（T5）、30 min（T6）、60 min（T7）、120 min（T8）、术毕（T9）记录患者的动脉血氧分压（PaO2）、动脉血二氧化碳分压（PaCO2）、肺毛细血管嵌压（PCWP）、肺动脉压（PAP）、肺血管阻力指数（PVRI）及氧合指数（PaO2/FiO2）,并计算各时点的肺内分流（Qs/Qt）量.结果Qs/Qt在术中稳定维持于26%～31%,PaO2/FiO2维持稳定状态.PaCO2在T5时点有所升高,后逐渐下降.PCWP在T2、T3、T4时点轻度下降,T5、T6时点有较快升高,后逐渐下降,至T9时点恢复至T0水平.PVRI于无肝期后逐渐升高、新肝期逐渐降低,至T7时点达T0水平.PAP的变化同PCWP相似,呈无肝期逐渐下降、新肝期逐渐上升的趋势,但T3、T4与T6时点相比差异有统计学意义.结论使用以氧供为导向的血流动力学管理模式对肝移植患者术中的肺功能具有一定的保护作用.     

X线第一前肋间肺静脉直径与肺毛细血管嵌压的关系及对心力衰竭诊断价值探讨

目的探讨X线第一前肋间肺静脉直径(PVDFAI)与肺毛细血管嵌压(PCWP)的关系及对心力衰竭(CHF)的诊断价值。方法入选住院呼吸困难患者195例,正常健康组67例,测定肺毛细血管嵌压(PCWP)并行后前位X线胸片检查,测量PVDFAI。以PCWP>12mmHg作为左心功能不全的诊断标准,将患者分为心衰组和肺源性呼吸困难组。计算PVDFAI诊断心衰的不同截值的敏感性、特异性、准确性。结果正常对照组PVDFAI(1.34±0.49)mm与肺源性呼吸困难组PVDFAI(1.43±0.37)mm差异无显著统计学意义(q=0.2700,P>0.05)。心源性呼吸困难组PVDFAI(2.49±0.93)mm与肺源性呼吸困难组和正常对照组比较均有明显增宽(q=17.0676,P<0.01;q=15.1143,P<0.01)。PVD-FAI与PCWP密切相关(r=0.388,P=0.000)。多元Logistic回归分析表明胸片PVDFAI是CHF的独立预测因子(P=0.000,比数比28.103)。PVDFAI判定肺源性呼吸困难或心衰,其曲线下面积95.24%(95%可信区间,91.73%~98.85%)。判断左心功能不全的PVDFAI最佳截值为2.5 mm,其诊断左心功能不全的敏感度97.17%,特异度93.26%,准确度95.38%。结论第一前肋间肺静脉直径可用以识别有、无肺静脉高压,对诊断心衰有价值。     

The use of milrinone in pre-transplant assessment of patients with congestive heart failure and pulmonary hypertension.

BACKGROUND: Pulmonary hypertension in patients with congestive heart failure (CHF) is a risk factor for increased mortality after orthotopic cardiac transplantation. Reversibility of elevated pulmonary vascular resistance (PVR) by pharmacologic agents predicts improved outcomes. Milrinone, a phosphodiesterase inhibitor with vasodilating and positive inotropic properties, has been shown to lower PVR in one previous study. However, no study has documented outcomes after cardiac transplantation in patients in whom reversibility of pulmonary hypertension was demonstrated after administration of milrinone. METHODS: We retrospectively reviewed 19 patients with CHF and pulmonary hypertension defined as PVR > or = 3 Wood units, PVRI (pulmonary vascular resistance index) > or = 4 resistance units, or TPG (transpulmonary gradient = mean pulmonary artery pressure--mean capillary wedge pressure) > or = 12 mmHg being assessed for cardiac transplantation. A sub-group of 14 patients with severe pulmonary hypertension defined as PVR > or = 4, PVRI > or = 6 and TPG > or = 15 was also examined. Milrinone was administered as a bolus (50 ug/kg) and hemodynamic parameters were measured at 5, 10 and 15 minutes. Six patients received cardiac transplants. RESULTS: Administration of milrinone significantly lowered PVR, PVRI, mean pulmonary artery pressure (PAM)(all p = 0.002) and pulmonary capillary wedge pressure (PCWP)(p = 0.006). Cardiac output (CO) increased significantly (p = 0.001). TPG did not change (p = 0.33). In patients with severe pulmonary hypertension, the magnitude of these changes was greater. In addition, TPG was significantly lowered (p = 0.02). CONCLUSION: Milrinone lowered PVR by decreasing PAM and increasing CO significantly. In addition, PCWP was significantly lowered. These finding confirm both vasodilatory and inotropic effects of milrinone. Patients with severe pulmonary hypertension had more pronounced effects. There were no deaths in the group of patients proceeding to cardiac transplantation. Our study demonstrates the efficacy of milrinone in lowering PVR as well as suggesting safety in use in patients undergoing cardiac transplantation.     

The influence of obesity and underweightness on respiratory function of geriatric patients undergoing surgery

We investigated the influence of obesity and underweightness on the respiratory function of 228 patients over 65ys. old undergoing elective surgery. The parameters we studied were preoperative Pa_{O 2} (Pa_{O 2}-pre), Pa_{O 2} under general anesthesia (Pa_{O 2}-op) and preoperative spirometric values including data from flow-volume curves and closing volumes. Triceps skinfold thickness (TSF), body mass index (BMI), Brocas index (BI) and Onoderas prognostic nutritional index (PNI) were measured or calculated. Respiratory parameters were compared between 3 groups; overweight (BMI 23), normal weight (BMI 20–22), underweight (BMI 19). Single and multiple correlations were analyzed between 3 nutritional parameters (BMI, TSF, PNI) and respiratory values. As a result, Pa_{O 2}-pre and Pa_{O 2}-op in overweight group were lower than those in the other groups. None of other parameters showed significant differences between the 3 groups. In multiple regression analysis, BMI correlated with Pa_{O 2}-pre (r = –0.24), Pa_{O 2}-op (r = –0.43), %VC (r = 0.18), peak flow rate (PFR, r = 0.17) and V¨₅₀/HT (r = 0.18). TSF correlated with Pa_{O 2}-pre (r = –0.22), %MVV (r = –0.28) and RV/TLC (r = 0.28). PNI correlated with PFR (r = 0.23). We concluded that overweightness has greater influence on respiratory function of elderly patients than underweightness and that arterial blood gas analysis is essential in preoperative assessment of obese geriatric patients.(Ochi G and Arai T: The influence of obesity and underweightness on respiratory function of geriatric patients undergoing surgery. J Anesth 6, 57–62, 1992)     

Effect of peak inspiratory flow on gas exchange, pulmonary mechanics, and lung histology in rabbits with injured lungs

Purpose The aim of this study was to evaluate, using a rabbit model, the little-known effect of different levels of peak inspiratory flow on acutely injured lungs. Methods Fourteen male rabbits (body weight, 2711 ± 146 g) were anesthetized and their lungs were injured by alveolar overstretch with mechanical ventilation until Pa_O2 was reduced below 300 mmHg. Injured animals were randomly assigned to: the P group—to receive pressure-regulated volume-control ventilation (PRVCV; n = 7); and the V group—to receive volume-control ventilation (VCV; n = 7). Other ventilator settings were: fraction of inspired oxygen (FI_O2), 1.0; tidal volume, 20 ml·kg⁻¹; positive end-expiratory pressure (PEEP) 5 cmH₂O; and respiratory rate, 20 min⁻¹. The animals were thus ventilated for 4 h. Throughout the protocol, ventilatory parameters and blood gas were measured every 30 min. After the protocol, the lung wet-to-dry ratio and histological lung injury score were evaluated in the excised lungs. Results Throughout the protocol, peak inspiratory flow and mean inspiratory flow values in the P group were significantly higher than those in the V group (26.7 ± 5.0 l·min⁻¹ vs 1.2 ± 0.2 l·min⁻¹, and 4.3 ± 0.3 l·min⁻¹ vs 1.1 ± 0.1 l·min⁻¹; P < 0.05). The wet-to-dry ratio in the P group was also significantly higher than that in the V group (7.7 ± 0.9 vs 6.3 ± 0.5; P < 0.05). More animals in the P group than in the V group had end-of-protocol Pa_O2/FI_O2 ratios below 200 mmHg (43% vs 0%; P = 0.06). Conclusion In rabbits with injured lungs, high peak inspiratory flow with high tidal volume (V_T) reduces the Pa_O2/FI_O2 ratio and increases the lung wet-to-dry ratio.     

The effects of amrinone and calcium chloride on pulmonary vasculature and biventricular function in ethchlorvynol-induced lung injury in sheep

The effects of amrinone and CaCl₂ on pulmonary vasculature and biventricular function in sheep with acute lung injury (ALI) were studied. Seven sheep were ventilated with a tidal volume of 10–12 ml.kg^-1 with end-tidal C0₂ of 40 ± 5 mmHg (5.3 ± 0.7 kPa) after acute lung injury was induced with up to 30 mg kg^-1 of ethchlorvynol (ECV). Biventricular function and hemodynamic profiles were estimated with a rapid computerized thermodilution method and modified pulmonary artery catheters after acute lung injury, following a loading dose (1 mg kg^-1) and maintenance dose (5 μg kg^-1 min-1 ) of amrinone and after a bolus dose of CaCl₂ (20 mg kg^-1). ECV successfully induced acute lung damage in sheep, causing significant increases in pulmonary artery pressure (PAP) and pulmonary vascular resistance index (PVRI). Amrinone reversed the unfavorable changes induced by ECV, significantly reducing PAP, PVRI and left ventricular end-diastolic volume (LVEDV). CaCl₂, however, reversed the effect of amrinone and increased PAP, PVRI, and LVEDV but decreased left ventricular ejection fraction.     

Risk factors for prolonged ICU stay in patients following coronary artery bypass grafting with a long duration of cardiopulmonary bypass

Purpose Risk factors for prolonged stay in the intensive care unit (ICU) in patients following coronary artery bypass grafting (CABG) have been reported in many previous studies. However few have focused on circulatory and respiratory status as immediate postoperative risk factors. Therefore we examined immediate postoperative risk factors for prolonged ICU stay after CABG with a long duration of cardiopulmonary bypass (CPB).Methods We studied retrospectively 100 consecutive patients undergoing elective CABG with CPB. Patients were excluded from this study if the duration of aortic cross-clamping was less than 60min. Patients were divided into three groups according to the duration of the ICU stay. Patients in group A (n = 68) were discharged from the ICU on the next morning after surgery, those in group B (n = 19) stayed for 3 days, and group C (n = 13) stayed for more than 3 days. Perioperative variables were compared among the three groups and we demonstrated risk factors for prolonged (more than 3 days) ICU stay.Results There were significant differences in duration of CPB (157 ± 34 versus 184 ± 48 minutes, P < 0.05) and aortic cross-clamping (119 ± 32 versus 141 ± 40min) between groups A and B. On the other hand, there were significant differences in age (62.8 ± 7.8 versus 67.4 ± 6.2 years), mean pulmonary artery pressure (MPAP) (17 ± 2 versus 22 ± 3mmHg), and Pa_{O 2}/FI _{O 2} (PF ratio) (409 ± 94 versus 303 ± 108mmHg) on admission to the ICU between groups A and C. There were no significant differences in intraoperative fluid balance and duration of CPB. Multiple logistic regression analysis identified age (>65 years), MPAP (>21mmHg), and PF ratio (<300mmHg) as independent risk factors for more than a 3-day ICU stay.Conclusion Advanced age, increased MPAP, and decreased PF ratio on admission to the ICU were significant risk factors for a prolonged ICU stay of more than 3 days.     

The cardiovascular effects of naloxone administration after fentanyl anesthesia in hypercapnic patients

Hemodynamic changes and plasma catecholamine levels after naloxone administration were studied in seventeen postoperative patients who received nitrous oxide, oxygen, and fentanyl anesthesia combined with epidural block. Group I consisted of ten postoperative hypercapnic (Pa_{CO 2} = 55.2 ± 2.4 torr) and group II seven postoperative normocapnic patients (Pa_{CO 2} = 38.4 ± 2.1 torr), respectively. In group I, naloxone reversal resulted in significant increases in heart rate (13.5%), mean arterial pressure (46.6%), systemic vascular resistance (32.1%), and rate pressure product (68.8%), whereas mean pulmonary artery pressure and pulmonary vascular resistance were significantly decreased. No significant hemodynamic changes after naloxone administration were observed in group II. There were no significant differences in arterial norepinephrine and epinephrine levels either before or after naloxone administration in the both groups. This study indicates that the postoperative hypercapnia elicits the cardiovascular stimulation after fentanyl reversal by naloxone.(Kishikawa K, Namiki A, Iwasaki H: The cardiovascular effects of naloxone administration after fentanyl anesthesia in hypercapnic patients. J Anesth 3: 48–53, 1989)     

Efficacy of nitroglycerin inhalation in reducing pulmonary arterial hypertension in children with congenital heart disease

Background. There has been a renewed interest in nitric oxidedonor drugs, such as nitroglycerin, delivered by the inhalationalroute for treatment of pulmonary arterial hypertension (PAH).We investigated the acute effects of inhaled nitroglycerin onpulmonary and systemic haemodynamics in children with PAH associatedwith congenital heart disease. Methods. Nineteen children with acyanotic congenital heart diseaseand a left to right shunt with severe PAH, undergoing routinediagnostic cardiac catheterization were included in this study.Systolic, diastolic and mean systemic as well as pulmonary arterypressures, right atrial pressure and pulmonary capillary wedgepressure (PCWP) were recorded and systemic vascular resistanceindex (SVRI) and pulmonary vascular resistance index (PVRI)were calculated at room air, following 100% oxygen as well asafter nitroglycerin inhalation in all patients. Results. Systolic, diastolic and mean pulmonary artery pressureand PVRI decreased significantly, whereas heart rate, systolic,diastolic and mean systemic arterial pressure, PCWP and SVRIdid not change significantly following 100% oxygen or inhalationof nitroglycerin. Conclusion. Inhaled nitroglycerin significantly decreases systolic,diastolic and mean pulmonary artery pressure as well as PVRIwithout affecting systemic haemodynamics, and thus can be usedas a therapeutic modality for acute reduction of PAH in childrenwith congenital heart disease.     

Continuous ketamine infusion for one- lung anaesthesia

The mechanism which normally affects distribution of blood flow through unventilated areas of the lung is hypoxic pulmonary vasoconstriction; this acts to divert the blood to well ventilated alveoli, resulting in a better ratio of ventilation to perfusion. Several reports have focused attention on the reduction or abolition of this reflex in the unventilated lung by most of the volatile anaesthetic agents used in clinical practice. This response was not abolished by the intravenous anaesthetic agents. One hundred and ten patients undergoing elective pulmonary resection were studied to evaluate the effect of a continuous infusion of ketamine during one-lung anaesthesia, by observing the changes in Pa₀₂as a reflection of shunt. Ketamine was chosen as the intravenous agent for its positive inotropic and chronotropic action. Additionally, by providing both analgesia and hypnosis, we were able to admininster inspired oxygen concentrations of 50-100 per cent without concern that the patient might have recall for events during operation We have demonstrated that in all cases a Pa₀₂ in excess of 9.31 kPa (70 torr) was achieved with ketamine and Fi₀₂1 .0as well as an increase in shunt fraction from 25.9 per cent (Fi₀₂0.5) to 36.0 per cent (Fi₀₂ 1.0). We feel that ketamine provides a satisfactory alternative to the volatile agents for one-lung anaesthesia in patients where relative hypoxaemia might be unacceptable during operation.