The Effect of Laparoscopic Cholecystectomy on Cardiovascular Function and Pulmonary Gas Exchange

The application of transcutaneous CO2 pressure monitoring in the anesthesia of obese patients undergoing laparoscopic bariatric surgery

To investigate the correlation and accuracy of transcutaneous carbon dioxide partial pressure (PTCCO2) with regard to arterial carbon dioxide partial pressure (PaCO2) in severe obese patients undergoing laparoscopic bariatric surgery. Twenty-one patients with BMI>35 kg/m(2) were enrolled in our study. Their PaCO2, end-tidal carbon dioxide partial pressure (PetCO2), as well as PTCCO2 values were measured at before pneumoperitoneum and 30 min, 60 min, 120 min after pneumoperitoneum respectively. Then the differences between each pair of values (PetCO2-PaCO2) and. (PTCCO2-PaCO2) were calculated. Bland-Altman method, correlation and regression analysis, as well as exact probability method and two way contingency table were employed for the data analysis. 21 adults (aged 19-54 yr, mean 29, SD 9 yr; weight 86-160 kg, mean 119.3, SD 22.1 kg; BMI 35.3-51.1 kg/m(2), mean 42.1,SD 5.4 kg/m(2)) were finally included in this study. One patient was eliminated due to the use of vaso-excitor material phenylephrine during anesthesia induction. Eighty-four sample sets were obtained. The average PaCO2-PTCCO2 difference was 0.9 ± 1.3 mmHg (mean ± SD). And the average PaCO2-PetCO2 difference was 10.3 ± 2.3 mmHg (mean ± SD). The linear regression equation of PaCO2-PetCO2 is PetCO2 = 11.58+0.57 × PaCO2 (r(2) = 0.64, P<0.01), whereas the one of PaCO2-PTCCO2 is PTCCO2 = 0.60 + 0.97 × PaCO2 (r(2) = 0.89). The LOA (limits of agreement) of 95% average PaCO2-PetCO2 difference is 10.3 ± 4.6 mmHg (mean ± 1.96 SD), while the LOA of 95% average PaCO2-PTCCO2 difference is 0.9 ± 2.6 mmHg (mean ± 1.96 SD). In conclusion, transcutaneous carbon dioxide monitoring provides a better estimate of PaCO2 than PetCO2 in severe obese patients undergoing laparoscopic bariatric surgery.

Comparison of transcutaneous, arterial and end-tidal measurements of carbon dioxide during laparoscopic cholecystectomy in patients with chronic obstructive pulmonary disease

OBJECTIVE

Transcutaneous, arterial and end-tidal measurements of carbon dioxide were compared in patients (American Society of Anesthesiology physical status classes II and III) with chronic obstructive pulmonary disease (COPD) who underwent laparoscopic cholecystectomy with carbon dioxide insufflation.

METHODS

General anaesthesia was performed in all patients. The Sentec(®) system was used for transcutaneous monitoring of the partial pressure of carbon dioxide (TcPCO(2)). TcPCO(2) and arterial partial pressure of carbon dioxide (PaCO(2)) were recorded preoperatively, after induction of anaesthesia, during insufflation and postoperatively; end-tidal carbon dioxide (ETCO(2)) was recorded after induction and during insufflation.

RESULTS

PaCO(2) increased during insufflation and reached a maximum at extubation. It declined within 20 min postoperatively but did not return to preoperative levels during this time. TcPCO(2) levels followed a similar pattern. ETCO(2) was significantly lower than PaCO(2) after induction and during insufflation.

CONCLUSION

TcPCO(2) was a valid and practical measurement compared with ETCO(2). In patients with COPD undergoing laparoscopic cholecystectomy, TcPCO(2) and ETCO(2) could be used instead of arterial blood gas sampling.

Transcutaneous carbon dioxide monitoring accurately predicts arterial carbon dioxide partial pressure in patients undergoing prolonged laparoscopic surgery

BACKGROUND

There may be large differences between measurements of end-tidal carbon dioxide partial pressure (Petco(2)) and arterial carbon dioxide partial pressure (Paco(2)) during laparoscopic surgeries. Transcutaneous carbon dioxide (Ptcco(2)) monitoring can be used to noninvasively and continuously estimate Paco(2). In the present study we evaluated the accuracy of Ptcco(2) monitoring in predicting the Paco(2) during laparoscopic surgeries with prolonged pneumoperitoneum.

METHODS

Sixteen patients who underwent laparoscopic radical gastrectomy or radical proctectomy under general anesthesia were included in the study. Their Paco(2), Petco(2), and Ptcco(2) values were measured at 3 time points before and after pneumoperitoneum. Agreement among measures was assessed by the Bland-Altman method.

RESULTS

Forty-eight sample sets were obtained. The average Paco(2)- Ptcco(2) difference was -0.9 + or - 6.4 mm Hg (mean + or - 2 SD). The average Paco(2) - Petco(2) difference was 7.5 + or - 7.0 mm Hg (mean + or - 2 SD). Paco(2) - Ptcco(2) was less than or equal to + or -5 mm Hg for 88% of the samples. Paco(2) - Petco(2) was less than or equal to + or -5 mm Hg for 17% of the samples (P < 0.05).

CONCLUSIONS

While undergoing long-term pneumoperitoneum laparoscopic surgery, Ptcco(2) monitoring is more accurate than is PETCO(2) monitoring in predicting the patients' Paco(2).

Diastolic function: the influence of pneumoperitoneum and Trendelenburg positioning during laparoscopic hysterectomy

BACKGROUND AND OBJECTIVE

Several reports concerning the haemodynamic changes during gynaecologic laparoscopy have been published so far, and the effects of head-down tilt and pneumoperitoneum have not been clearly separated. However, its main effect seems to be an increase in systemic vascular resistance. We investigated how the augmented afterload can affect diastolic function.

METHODS

: Our study involved 20 healthy women, classified as having ASA status I: 10 undergoing laparoscopic hysterectomy and 10 undergoing conventional open hysterectomy. Measurements were made in awake patients and after induction of anaesthesia and then repeated after carbon dioxide insufflation and head-down positioning and at the end of surgery. Diastolic function was primarily studied by transthoracic echocardiography.

RESULTS

We observed that pneumoperitoneum caused a significant reduction in stroke volume, cardiac output and left ventricular end-diastolic volume; the diastolic filling times showed a progressive reduction in the E-velocity (the velocity of early mitral inflow, corresponding to the ventricular passive filling phase, measured by pulsed-wave Doppler), a prolonged deceleration time and an augmented isovolumetric relaxation time. After head-down tilting, stroke volume, cardiac output and left ventricular end-diastolic volume increased in both laparoscopic hysterectomy and conventional open hysterectomy groups.

CONCLUSION

We have found that pneumoperitoneum has important effects on left ventricular volumes, causing a drop in left ventricular end-diastolic volume; it also affects diastolic function with a delay in deceleration time and isovolumetric relaxation time without any effects on intracavitary pressures.

Effect of Small Bowel Perforation During Laparoscopy on End-Tidal Carbon Dioxide: Observation in a Small Animal Model

INTRODUCTION

There are currently no reports in the literature regarding changes in end-tidal carbon dioxide (ETCO(2)) when the small bowel is deliberately or inadvertently perforated during laparoscopic surgery. The aim of this study was to assess the influence of small bowel perforation during laparoscopy on ETCO(2) in a rat model.

MATERIALS AND METHODS

Two groups of Wistar rats (n = 8/group) were anesthetized, tracheostomized, and mechanically ventilated at a fixed tidal volume and respiratory rate. After a stabilization phase of 30 min, CO(2) pneumoperitoneum was established to 5 mmHg in one group and 12 mmHg in the other group, and maintained for 30 min. A small bowel perforation was then created and pneumoperitoneum was reestablished for another 30 min. Blood pressure, heart rate, peak ventilatory pressure, and ETCO(2) were recorded throughout the experiment.

RESULTS

No significant changes in blood pressure throughout the experiment were noted in either group. The ventilatory pressure increased in both groups after the induction of pneumoperitoneum. In the 5 mmHg group, there was a modest increase in ETCO(2) following the induction of pneumoperitoneum (from 39.4 +/- 1.9 to 41.1 +/- 1.4, P = 0.014), and a further increase following the small bowel perforation (from 41.1 +/- 1.4 to 42 +/- 0.8, P = 0.007). In the 12 mmHg group, there was no change in ETCO(2) after the induction of pneumoperitoneum; however, there was a substantial increase in ETCO(2) following bowel perforation (35.0 +/- 2.0 to 49.8 +/- 7.1, P = 0.002).

CONCLUSIONS

ETCO(2) increases when the small bowel is perforated during CO(2) pneumoperitoneum. This increase seems more substantial under higher pneumoperitoneal pressures. Small bowel injury may enable the diffusion of CO(2) through the bowel mucosa, causing ETCO(2) elevation. Therefore, an abrupt increase in ETCO(2) observed during laparoscopy may indicate small bowel injury.

Comparison of cardiopulmonary responses during sedation with epidural and local anesthesia for laparoscopic-assisted jejunostomy feeding tube placement with cardiopulmonary responses during general anesthesia for laparoscopic-assisted or open surgical jejunostomy feeding tube placement in healthy dogs

OBJECTIVE

To evaluate the use of laparoscopic-assisted jejunostomy feeding tube (J-tube) placement in healthy dogs under sedation with epidural and local anesthesia and compare cardiopulmonary responses during this epidural anesthetic protocol with cardiopulmonary responses during general anesthesia for laparoscopic-assisted or open surgical J-tube placement.

ANIMALS

15 healthy mixed-breed dogs.

PROCEDURES

Dogs were randomly assigned to receive open surgical J-tube placement under general anesthesia (n = 5 dogs; group 1), laparoscopic-assisted J-tube placement under general anesthesia (5; group 2), or laparoscopic-assisted J-tube placement under sedation with epidural and local anesthesia (5; group 3). Cardiopulmonary responses were measured at baseline (time 0), every 5 minutes during the procedure (times 5 to 30 minutes), and after the procedure (after desufflation [groups 2 and 3] or at the start of abdominal closure [group 1]). Stroke volume, cardiac index, and O(2) delivery were calculated.

RESULTS

All group 3 dogs tolerated laparoscopic-assisted J-tube placement under sedation with epidural and local anesthesia. Comparison of cardiovascular parameters revealed a significantly higher cardiac index, mean arterial pressure, and O(2) delivery in group 3 dogs, compared with group 1 and 2 dogs. Minimal differences in hemodynamic parameters were found between groups undergoing laparoscopic-assisted and open surgical J-tube placement under general anesthesia (ie, groups 1 and 2); these differences were not considered to be clinically important in healthy research dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Sedation with epidural and local anesthesia provided satisfactory conditions for laparoscopic-assisted J-tube placement in healthy dogs; this anesthetic protocol caused less cardiopulmonary depression than general anesthesia and may represent a better choice for J-tube placement in critically ill patients.

Maternal hemodynamic changes following treatment by laser coagulation of placental vascular anastomoses and amnioreduction in twin-to-twin transfusion syndrome

OBJECTIVES

To investigate maternal hemodynamic changes following laser therapy and amnioreduction in twin-to-twin transfusion syndrome (TTTS).

METHODS

Thirty-nine cases with severe TTTS were treated at 16-26 weeks of gestation. Maternal hemodynamic evaluation was performed, including heart rate (HR), arterial pressure and echocardiography with calculation of shortening fraction (SF), left atrial dimensions, stroke volume (SV), cardiac output (CO) and total vascular resistance (TVR), before and 6 h and 24 h after placental surgery. Hemoglobin (Hb), hematocrit (Ht) and protein levels were also measured. Cases were retrospectively divided into groups according to treatment: Group A had laser therapy followed by amnioreduction >1000 mL (n = 25); Group B had laser therapy followed by amnioreduction <1000 mL (n = 14).

RESULTS

The mean gestational age at inclusion was 21 (range, 16-26) weeks. The mean amniotic fluid withdrawal was 1700 (range, 1000-3000) and 300 (range, 150-800) mL in Groups A and B, respectively. Cases in Group A showed a decrease in mean arterial blood pressure (P = 0.011) and in TVR (P < 0.0001) and an increase in CO (P = 0.008) and SV (P = 0.022). There was no difference in HR. Significant hemodilution developed as early as 6 h after the procedure, with a reduction in Ht (P < 0.0001), plasma protein (P < 0.0001) and Hb levels of 1.2 g/dL on average (P < 0.0001). There were no changes in any parameters in Group B.

CONCLUSIONS

Amnioreduction of severe polyhydramnios in TTTS induces maternal hemodynamic changes within the first 6 h that persist at least 24 h after treatment. These adaptative changes are compatible with hemodilution.

Effect of CO(2) pneumoperitoneum on ventilation-perfusion relationships during laparoscopic cholecystectomy

BACKGROUND

Previous studies have shown that pneumoperitoneum transiently reduces venous admixture as assessed by a calculation based on the shunt formula, and increases arterial oxygen tension (PaO(2)) in patients without heart or lung disease. The aim of the present study was to further explore the relationship between ventilation-perfusion (V(A)/Q) before and during pneumoperitoneum by using the multiple inert gas technique.

METHODS

Nine patients without heart or lung disease (ASA I), with a mean age of 42 years, scheduled for laparoscopic cholecystectomy were included. After premedication and induction of anaesthesia, radial artery and pulmonary artery catheters were introduced percutaneously. The V(A)Q relationships were evaluated by the multiple inert gas elimination technique before and during pneumoperitoneum to obtain a direct measure of the pulmonary shunt.

RESULTS

Induction of pneumoperitoneum decreased the pulmonary shunt from 5.8 (4.5) to 4.1 (3.2)% (P<0.05) and increased PaO(2) from 21.7 (5.9) to 24.7 (4.8) kPa (P<0.01). During surgery, the shunt increased from 3.2 (2.8) to 5.2 (3.4)% to the same level as before pneumoperitoneum induction. No area with low V(A)Q was seen. Dead space ventilation amounted to 20.0 (1.2)% in the supine position and did not change during the investigation.

CONCLUSIONS

In patients without heart or lung disease, pneumoperitoneum at an intra-abdominal pressure level of 11-13 mmHg causes a transient reduction of the pulmonary shunt. The mechanisms underlying the present finding remain to be elucidated.

[Recovery of lung function after laparoscopic cholecystectomy: the role of postoperative pain]

OBJECTIVES

Lung function has been shown to deteriorate after laparoscopic cholecystectomy (LC). The present study evaluated 1) the rate of recovery after LC, and 2) the pathogenic role of postoperative pain in functional deterioration.

DESIGN

Lung function was measured 24 hours before LC, upon hospital discharge (48-72 h after LC), and 10 days later. All patients received metamizol after LC until discharge (2 g every 6 h i.v.). Half the patients (analgesia group) received tramadol (150 mg i.m.) 30 minutes before lung function testing on the day of hospital discharge. The remaining patients constituted the control group.

PATIENTS

Twenty healthy subjects (53 4 years old) undergoing LC for gall bladder removal. All signed informed consent forms. Measures and outcomes: Patient characteristics and preoperative lung function results were similar in both groups. LC duration and postoperative course were also similar in both groups. All were discharged without complications within 72 hours after LC. Lung function upon discharge (FVC, FEV1, TLC, PaO2 and AaPO2) had deteriorated in both groups (p<0.001). Deterioration was less marked in the analgesia group (p < 0.05). Ten days later, lung function had normalized for all subjects.

CONCLUSIONS

These results indicate that after LC, 1) lung function is still abnormal when the patient is discharged from hospital, 2) lung function has fully recovered within 10 days, and 3) postoperative pain contributes significantly to temporary deterioration in lung function.

Pigs are not a reliable experimental model in the study of the haemodynamic and respiratory effects of CO2 pneumoperitoneum

BACKGROUND

Haemodynamic and respiratory effects of a CO2 pneumoperitoneum (intra-abdominal pressure = 12 mmHg) associated to a head-up position(15 degrees ) were studied in 20 pigs using a Swan-Ganz catheter and the Single Breath Test for CO2. The pneumoperitoneum induced a moderate rise in mean arterial pressure (+17%) (P<0.001) without any variation in heart rate, cardiac output and systemic vascular resistances.

RESULTS

The following respiratory effects were observed: an increase in PaCO2 (+20%) (P<0.001), PE'CO2 (+31%) (P<0.001), expired volume of CO2 (+28%) (P<0.001), arterial to end-tidal CO2 gradient (+80%) (P<0.001) and alveolar dead space (+40%) (P<0.001) occured. Alveolar ventilation remained stable. Finally and contrary to healthy human patient, intraperitoneal CO2 insufflation in pig induced slight haemodynamic changes and major respiratory modifications.

CONCLUSION

Thus, our data do not support the conclusion that the pig is a reliable experimental model for studying the pathophysiology of CO2 pneumoperitoneum-induced changes in haemodynamic and respiratory parameters, in human patients.

Complications of laparoscopy

The frontiers of laparoscopic surgery have extended from gynecologic procedures to general surgical techniques. As new applications for laparoscopy emerge, anesthesiologists must be familiar with the possible complications associated with the various laparoscopic procedures. Only by an appreciation of the potential complications of a procedure can their overall incidence be minimized. A systematic approach must consider all potential complications during laparoscopy. In addition to routine evaluation (i.e., depth of anesthesia and volume status), anesthesiologists must confirm that intra-abdominal pressure is less than 15 mm Hg, and that inadvertent endobronchial intubation, pneumothorax, and gas embolism have not occurred. In the case of precipitous changes in vital signs not responding to routine management, it is imperative to release the pneumoperitoneum and place the patient in the supine (or Trendelenburg) position. After cardiopulmonary stabilization, cautious slow reinsufflation then can be attempted. With persistent signs of significant cardiopulmonary impairment, however, it is sometimes necessary to convert to an open procedure.

Renal physiology. Laparoscopic considerations

Oliguria is a recognized component of the physiologic effect of increased intra-abdominal or retroperitoneal pressure. The cause is multifactorial, emanating from vascular and parenchymal compression, and is associated with systemic hormonal effects. Ureteral obstruction does not play a significant role. These changes are pressure-dependent and are usually not apparent until pressures reach 15 mm Hg or more. This effect is not associated with any histologic pathology or evidence of renal tubular damage. After the release of the pneumoperitoneum or pneumoretroperitoneum, the renal function and urine output return to normal with no long-term sequelae, even in patients with pre-existing renal disease. The entire operative team must understand the physiologic effects of CO2 insufflation, which allows appropriate intraoperative monitoring and management and minimizes intraoperative and postoperative complications.

Cardiocirculatory changes during videolaparoscopy in children: an echocardiographic study

We examined cardiovascular changes associated with intra-abdominal insufflation in 20 children (mean age 6.1+/-4.7 years, ASA physical status I or II) undergoing laparoscopic surgery with general anaesthesia using echocardiography with a transthoracic approach. Intra-abdominal pressure never exceeded 10 mmHg. Systolic blood pressure, diastolic blood pressure, endtidal CO2, peak, and mean airway pressure increased during intra-abdominal insufflation (P < 0.001). Pneumoperitoneum was associated with increases (P<0.001) in left ventricular enddiastolic volume, left ventricular end-systolic volume and left ventricular endsystolic meridional wall stress. In addition, before, during and after intra-abdominal insufflation, left ventricular fractional shortening and left ventricular ejection fraction, underwent slight, insignificant changes. Pneumoperitoneum in children has a major impact on cardiac volumes and function, mainly through the effect on ventricular load conditions. The sharp increase in intra-abdominal pressure affects both preload and afterload, while systolic cardiac performance remains unchanged.

Haemodynamic changes during laparoscopic anterior fundoplication measured by trans-oesophageal Doppler ultrasound

We investigated the cardiovascular effects of pneumoperitoneum and steep head-up tilt during laparoscopic fundoplication using an intra-oesophageal Doppler ultrasound probe. Repositioning of the probe proved sufficient to maintain the signal throughout the procedure despite the pneumomediastinum. There was a statistically significant increase in mean arterial blood pressure and a fall in stroke distance but not in systemic vascular resistance. Increasing or decreasing the blood pressure with drugs improved stroke distance. The oesophageal Doppler ultrasound proved a satisfactory method for assessing cardiovascular changes during fundoplication.

Acute renal failure following laparoscopic cholecystectomy: a case report

The carbon dioxide (CO2) pneumoperitoneum of laparoscopic surgery is a complex physiologic event associated with neuroendocrine, respiratory, cardiovascular, and renal disturbances, as well as compromised organ blood flow. A case is presented of a 67-year-old man with a history of chronic renal failure, renal tubular acidosis, and hypertension, who underwent an uneventful elective laparoscopic cholecystectomy that included 75 minutes of CO2 pneumoperitoneum of 15 mmHg pressure. Postoperatively, the patient developed acute renal failure from which he recovered within 2 weeks. In the absence of other evident precipitating factors, we suspect that the CO2 pneumoperitoneum played a causal role in the development of his acute renal failure. The potential seriousness of the physiologic insult of conventional CO2 pneumoperitoneum suggests that "minimal access" surgery is not necessarily "minimally invasive."

[Hemodynamic monitoring using esophageal Doppler ultrasonography during laparoscopic cholecystectomy]

PURPOSE

To evaluate the use of a 4-mHz continuous wave esophageal Doppler monitor in the hemodynamic management of 48 ASA I to III patients undergoing laparoscopic cholecystectomy.

METHODS

General anesthesia was induced with fentanyl and propofol, maintained with N20 N20/02 and muscle relaxation was provided with atracurium. The lungs were mechanically ventilated. Non invasive arterial blood pressure, heart rate, capnography, arterial blood gas were monitored during CO2 pneumoperitoneum at 15-mmHg. Using the velocity waveform of descending aortic blood flow, the Doppler device estimated changes in cardiac output and systemic vascular resistances.

RESULTS

Peritoneal insufflation resulted in a mean 19% decrease in cardiac output (range -49 to +5%; P < 0.05) and a mean 48% increased in systemic vascular resistances (range -7 to +101%; P < 0.01). There was no relationship between changes in cardiac output and mean arterial pressure or PETCO2. The esophageal Doppler provided, in two patients, details of hypertensive peaks (mean arterial pressure > 140 mmHg) which responded to administration of nicardipine.

CONCLUSION

The Esophageal Doppler provided an easy-to-handle and non invasive tool to monitor changes in cardiac output during laparoscopic cholecystectomy. However, further comparison with a thermodilution cardiac output technique is required.

Respiration during emergence from anaesthesia with desflurane/N2O vs. desflurane/air for gynaecological laparoscopy

BACKGROUND

The complications related to anaesthesia usually occur in the early postoperative period. Hypercapnia and hypoxaemia may result from any persistent depression of the respiratory drive relative to the metabolic demand. The purpose of this study was to compare the respiratory effects of desflurane anaesthesia with or without nitrous oxide during the period of emergence.

METHODS

Twenty patients scheduled for a standardised surgical procedure, laparoscopic hysterectomy, were randomly allocated to anaesthesia with 1.3 MAC of desflurane/N2O (Group 1) or desflurane alone (Group 2), with 10 patients in each group. Times of resumption of spontaneous breathing and extubation were recorded and elimination rates of carbon dioxide, end-tidal concentrations of desflurane and N2O, and blood gases were measured.

RESULTS

Spontaneous breathing was resumed in both groups when pH had decreased by about 0.07 and PaCO2 increased by about 1.4 kPa compared with the values at the end of 1.3 MAC anaesthesia with controlled normoventilation. There were no significant differences between the groups with regards to extubation time, 6 vs. 13 min, or total MAC value at extubation, 0.20 vs. 0.19 in Group 1 and 2, respectively. Neither did the groups differ in minute ventilation, end-tidal carbon dioxide, oxygen concentrations, or blood gases. CO2 elimination decreased in both groups from about 220 ml 70 kg-1 min-1 at the end of anaesthesia to a lowest value of about 160 ml 70 kg-1 min-1.

CONCLUSION

The respiratory profiles during recovery from gynaecological laparoscopy with either desflurane/N2O or desflurane anaesthesia were similar with fast resumption of spontaneous breathing, short time to extubation, and no signs of CO2 retention.

Left ventricular loading modifications induced by pneumoperitoneum: a time course echocardiographic study

The intraperitoneal insufflation of carbon dioxide during laparoscopic procedures is associated with an increase in mean arterial pressure and systemic vascular resistance. To evaluate the time course of the circulatory changes related to intraabdominal pressure variation, we used transesophageal echocardiography in 10 patients anesthetized for laparoscopic cholecystectomy. Left ventricular dimensions, fractional area shortening (FAS), and left ventricular afterload assessed by the left ventricular end-systolic wall stress (LVESWS) were measured from echocardiographic data before insufflation, during pneumoperitoneum, and during exsufflation. Three minutes after the onset of pneumoperitoneum, we observed a 25.7% +/- 10.5% (mean +/- SD) increase in mean arterial pressure, a 49.1% +/- 14.4% increase in LVESWS, and a 17.0% +/- 16.2% decrease in FAS. All measured variables returned to preinsufflation values after 30 min of pneumoperitoneum and thereafter were no longer significantly affected by postural changes (10 degrees head-up position) or pneumoperitoneum exsufflation. We conclude that the circulatory changes associated with pneumoperitoneum are transient and are probably mediated by factors other than intraabdominal pressure variations.

IMPLICATIONS

Insufflation of gas into the abdominal cavity results in hemodynamic changes during laparoscopic procedures. We found that echocardiographic and blood pressure effects associated with gas insufflation were transient, indicating mediation by factors besides intraabdominal pressure.

The hemodynamic effects of pneumoperitoneum during laparoscopic surgery in healthy infants: assessment by continuous esophageal aortic blood flow echo-Doppler

Cardiovascular changes due to pneumoperitoneum during laparoscopic surgery are established in adult patients, but not known in infants. We investigated the hemodynamic effects of laparoscopy during general anesthesia in 12 ASA physical status I infants by using noninvasive continuous esophageal aortic blood flow (ABF) echo-Doppler monitoring. During the laparoscopic procedure, intraabdominal pressure was maintained automatically at 10 mm Hg by a CO2 insufflator, and minute ventilation was adjusted to avoid hypercapnia. Hemodynamic changes were continuously recorded on soft magnetic support and assessed at three time intervals: t0 (after the initiation of anesthesia), t1 (5 min after peritoneal insufflation), and t2 (5 min after exsufflation). The induction of pneumoperitoneum resulted in a significant decrease in ABF and stroke volume, and in a significant increase in systemic vascular resistance, compared with control values: 67% +/- 9% (P < 0.001), 68% +/- 10% (P < 0.001), and 162% +/- 34% (P < 0.001), respectively. These changes were completely reversed after peritoneal exsufflation. Pneumoperitoneum caused no significant changes in mean arterial pressure or in end-tidal CO2 pressure. These findings demonstrate that laparoscopy is associated with hemodynamic changes without clinically deleterious consequences in healthy infants during a short duration of pneumoperitoneum.

IMPLICATIONS

The peritoneal insufflation achieved during laparoscopic surgery is associated with cardiovascular impairments (decrease in cardiac performance and increase in vascular resistance). We found that these changes had no clinically deleterious effects in healthy infants.

Should nitrous oxide be discontinued before desflurane after anaesthesia with desflurane/N2O?

BACKGROUND

The appearance of hypoxaemia immediately after anaesthesia with nitrous oxide may be partially explained by diffusion hypoxia. This study was undertaken to evaluate circulatory and respiratory variables during emergence after desflurane/nitrous oxide anaesthesia, and whether there are any differences depending on which gas is discontinued first.

METHODS

20 patients were studied after gynaecological laparoscopic surgery. The depth of anaesthesia was reduced 10 min prior to the emergence by stopping the administration of one of the two inhalational agents. Desflurane was discontinued first in Group 1, nitrous oxide in Group 2. Ventilation was controlled with E'CO2 maintained at 5% until the administration of the second anaesthetic gas was discontinued. Thereafter, the patients breathed spontaneously.

RESULTS

The PaCO2 at which the respiratory drive reappeared after controlled normoventilation was similar in both groups, 6.1-6.5 kPa, and extubation was performed after 10-11 min. At extubation, the end-tidal CO2 and total MAC were similar in the groups, about 6.2 vol% and 0.16, respectively. Mean arterial blood pressure was significantly higher in Group 1. The cardiac output increased in both groups from about 6 l/min at the conclusion of anaesthesia to 9.0 and 7.6 l/min at 15 min in the recovery period. End-tidal O2 decreased and CO2 increased in both groups during the first 10 min in the recovery period. pH was reduced at 15 and 30 min in both groups.

CONCLUSION

Irrespective of which agent was discontinued first there was an increase in cardiac output decrease in oxygenation and a modest acidosis in the first 30-min recovery period. The only significant difference between the groups was in mean arterial blood pressure in the early emergence phase with a greater MAP when N2O had been used until the conclusion of anaesthesia.

Ventilatory effects of laparoscopic cholecystectomy under general anesthesia

PURPOSE

To investigate the ventilatory effect of laparoscopic cholecystectomy in patients under general anesthesia with epidural block.

METHODS

We measured arterial blood gas, pulmonary carbon dioxide elimination (0000126;_ECO₂), the dead space/tidal volume ratio (V_D/V_T), and the alveolar-arterial PO₂ difference [(A-a)DO₂] just before and 5, 10, 20, 40, and 80 min after peritoneal insufflation in eight patients who underwent laparoscopic cholecystectomy under general anesthesia with epidural block. The effect of laparoscopic cholecystectomy on these values was evaluated. The patients were ventilated on the controlled mode by Servo 900C with a constant tidal volume (V_T 10ml·kg^-1) and frequency (respiratory rate 12 breaths·min^-1) throughout the study.

RESULTS

After starting peritoneal insufflation the PaCO₂ showed a sudden increase during the initial 10 min of about 4 mmHg followed by a gradual increase thereafter. The increase in000123;_ECO₂ was about 30ml·min^-1 (20%) on average during the initial 20 min, and a plateau was reached within 20-40 min after peritoneal insufflation. Neither V_D/V_T nor (A-a)DO₂ showed significant changes during the study.

CONCLUSION

These results suggest that (1) transperitoneal absorption of CO₂ may be the main cause of hypercarbia, and the hypercarbia is not attributed to the increase in V_D/V_T; and (2) oxygenation is not impaired during pneumoperitoneum.