The adverse hemodynamic effects of anesthesia, head-up tilt, and carbon dioxide pneumoperitoneum during laparoscopic cholecystectomy

Background: The increased intra-abdominal pressure during pneumoperitoneum, together with the head-up tilt used in upper abdominal laparoscopies, would be expected to decrease venous return to the heart. The goal of our study was to determine whether laparoscopy impairs cardiac performance when preventive measures to improve venous return are taken, and to analyze the effects of positioning, anesthesia, and increased intra-abdominal pressure. Methods: Using invasive monitoring, hemodynamic changes were investigated in 15 ASA class I or II patients under isoflurane–fentanyl anesthesia during laparoscopic cholecystectomy. Before laparoscopy, the patients received an intravenous (IV) infusion of colloid solution if cardiac filling pressures were low, and their legs were wrapped from toes to groin with elastic bandages. Measurements were taken while the patients were awake in the supine (baseline) and head-up tilt (15–20°) positions, and after the induction of anesthesia in the same positions. Measurements were repeated at regular intervals during laparoscopy (intra-abdominal pressure at 13–16 mmHg), after deflation of the gas, and in the recovery room. Results: With the passive head-up tilt in awake and anesthetized patients, the cardiac index (CI), stroke index (SI), central venous pressure (CVP), and pulmonary capillary wedge pressure (PCWP) decreased, and systemic vascular resistance increased. With the patient under anesthesia, SI decreased, but CI did not change significantly as a result of the compensatory increase in heart rate. Carbon dioxide (CO₂) insufflation at the start of laparoscopy produced increases in CVP and PCWP as well as mean systemic and mean pulmonary arterial pressures without changes in CI or SI. Toward the end of the laparoscopy, CI decreased by 15%. The hemodynamic values returned to nearly prelaparoscopic levels after deflation of the gas, and CI was elevated during the recovery period, whereas systemic vascular resistance was decreased in comparison with the baseline. Conclusions: By correcting relative dehydration and preventing the pooling of blood, CI decreased less than 20% during pneumoperitoneum as compared with the baseline awake level. The head-up positioning accounts for many of the adverse effects in hemodynamics during laparoscopic cholecystectomy. Received: 6 November 1998/Accepted: 8 July 1999     

Reversal of adverse hemodynamic effects of pneumoperitoneum by pressure equilibration

HYPOTHESIS: The creation of positive-pressure pneumoperitoneum during laparoscopic operations can lead to adverse hemodynamic changes, mainly decreased cardiac output. We hypothesized that pneumatic compression sleeves worn on the legs during pneumoperitoneum could abolish the pressure gradient between the abdominal cavity and the legs and so eliminate these adverse hemodynamic changes. DESIGN: Prospective, randomized, controlled clinical trial with an additional calibration group. SETTING: A regional referral center. PATIENTS: Forty-five consecutive patients undergoing laparoscopic cholecystectomy who developed hemodynamic changes on induction of positive-pressure pneumoperitoneum were randomized to 3 groups. INTERVENTIONS: Low-pressure, nonsequential pneumatic compression sleeves, wrapped around the legs, were used to equilibrate the pressure gradient in the study group and to gradually exceed it in the calibration group. In the control group, no sleeves were used. MAIN OUTCOME MEASURES: Transesophageal Doppler cardiac output, stroke volume, and systemic vascular resistance were monitored noninvasively. RESULTS: The creation of positive-pressure pneumoperitoneum caused a significant decrease of cardiac output and stroke volume and increased systemic vascular resistance. In the experimental groups of patients, pressurizing the sleeves to the pneumoperitoneal pressure caused a significant increase of cardiac output (from 4.82 to 6.74 L/min), increased stroke volume, and decreased systemic vascular resistance (P<.001). This was not seen in the control group. Additional gradual pressure increase in the sleeves of the calibration group produced no further improvement. Releasing the pressure abolished the hemodynamic advantages. CONCLUSIONS: Applying pressure on the legs equivalent to the positive-pressure pneumoperitoneum improves hemodynamic performance during pneumoperitoneum by nullifying the pressure gradient that is responsible for the adverse consequences. This might be of major practical value, especially for cardiac patients undergoing prolonged laparoscopic operations.     

Systematic evaluation of different approaches for minimizing hemodynamic changes during pneumoperitoneum

BACKGROUND: Capnoperitoneum (CP) compromises hemodynamic function during laparoscopy. Three therapeutic concepts were evaluated with an aim to minimize the hemodynamic reaction to CP: First, a controlled increase of intrathoracic blood volume (ITBV) by intravenous fluids; second, partially reduced sympathetic activity by the beta1-blocker esmolol; and third, a decrease in mean arterial pressure (MAP) by the vasodilator sodium nitroprusside. METHODS: For this study, 43 pigs were assigned to treatment with fluid and sodium nitroprusside (group A) or with esmolol (group B). In both groups, the pigs were assigned to head-up, head-down, or supine position, resulting in three different subgroups. Invasive hemodynamic monitoring was established including left heart catheter and cardiac oxygen lung water determination (COLD) measurements. Measurements were documented before CP with the animals in supine position, after induction of a 14-mmHg CP with the animals in each body position, after a 10% reduction in MAP by vasodilation, and after an increase in ITBV of about 30% by infusion of 6% hydroxyethylstarch solution. RESULTS: Increasing ITBV improved hemodynamic function in all body positions during CP. Esmolol reduced cardiac output and myocardial contractility. Sodium nitroprusside did not improve hemodynamic function in any body position. CONCLUSIONS: Optimizing volume load is effective for minimizing hemodynamic changes during CP in the head-up and in head-down positions. In general, beta(1)-blockers cannot be recommended because they might additionally compromise myocardial contractility and suppress compensatory reaction of the sympathetic nerve system. Vasodilation has not improved hemodynamic parameters during CP.     

The effects of low-pressure carbon dioxide pneumoperitoneum on cerebral oxygenation and cerebral blood volume in children

We examined the effects of low-pressure carbon dioxide pneumoperitoneum on regional cerebral oxygen saturation (ScO(2)) and cerebral blood volume (CBV) in children. Fifteen children, ASA I--III, scheduled for laparoscopic fundoplication, were investigated in the head-up position (10) and ventilated to a baseline end-tidal CO(2) (PETCO(2)) between 25 and 33 mm Hg. Ventilatory settings remained unchanged during the operation. ScO(2) and CBV were assessed with near-infrared spectroscopy and recorded together with end-tidal and arterial carbon dioxide (PaCO(2)) at 5 time points: before insufflation, 30, 60, and 90 min after the start of CO(2) insufflation, and 10 min after desufflation. The intraabdominal pressure was kept between 5 and 8 mm Hg. During insufflation, PETCO(2) increased from 30.0 plus minus 2.8 to 38.3 plus minus 5.1 mm Hg (P < 0.001) and PaCO(2) increased from 32.0 plus minus 4.7 to 40.4 plus minus 5.9 mm Hg (P < 0.001). ScO(2) increased by 15.7% plus minus 8.8% (from 61 plus minus 9 to 70 plus minus 9 arbitrary units ) (P < 0.001). CBV increased by 4.6% plus minus 8.8% (from 123 plus minus 66 to 128 plus minus 66 arbitrary units [P = 0.048]). After desufflation, PETCO(2) and PaCO(2) decreased, but did not return to preinsufflation values. ScO(2) and CBV also decreased after desufflation. In conclusion, hyperventilation and the head-up position before CO(2) insufflation are not sufficient to prevent the CO(2)-mediated cerebral hemodynamic effects of low-pressure pneumoperitoneum (5--8 mm Hg) in children. IMPLICATIONS: Peritoneal CO(2) absorption during laparoscopic surgery causes hypercapnia and CO(2)-mediated cerebral hemodynamic effects. Hyperventilation and the head-up position before CO(2) insufflation is not sufficient to counteract these effects of low-pressure pneumoperitoneum (5--8 mm Hg) in children.     

Impedance cardiography. Current status and clinical applications

Impedance cardiography is a highly reproducible, rapid and safe method for the evaluation of cardiac performance in the clinical setting. Measurements of stroke volume (SV), end diastolic volume (EDV), and end systolic volume (ESV) with calculation of cardiac output (CO) were obtained in normal, healthy people (group 1, n = 21) and in patients with congestive heart failure (group 2, n = 18). Individuals were placed on a tilt table and cardiac profiles (measurements of CO, SV, EDV, and ESV) were performed at 45 degrees head up, 15 degrees head up, and supine. Group 1 responded by increasing CI from 2.9 +/- 0.81 L/min/M2 at 45 degrees to 3.3 +/- 1.0 L/min/M2 at 15 degrees to 3.7 +/- 1.0 L/min/M2 supine. There was no corresponding rise seen in group 2, with CIs of 2.1 +/- 0.83 L/min/M2, 2.0 +/- 0.78 L/min/M2 and 2.0 +/- 0.76 L/min/M2 at each position, respectively. In addition, while the EDV increased at each position in group 1 (45 degrees: 71 +/- 21 cc/M2, 15 degrees: 88 +/- 26 cc/M2, Supine: 102 +/- 29 cc/M2), no such increase was evident in group 2 (45 degrees: 57 +/- 29 cc/M2, 15 degrees: 52 +/- 20 cc/M2, Supine: 60 +/- 24 cc/M2). The inability of group 2 patients to elevate CI and the absence of any discernible change in EDV suggests an insufficiency of cardiac reserve with noncompliant ventricles. This information is currently being used to assess operative risk and to study effects of treatment modalities.     

Changes in intrathoracic blood volume associated with pneumoperitoneum and positioning

BACKGROUND: It is still controversial whether elevated cardiac filling pressures after the onset of pneumoperitoneum are the consequence of increased intrathoracic pressure or of increased venous return. The aim of this study was to assess the effects of pneumoperitoneum and body positioning on intrathoracic blood volume (ITBV). METHODS: Thirty anesthetized patients were randomly assigned to have CO2-pneumoperitoneum (13 mmHg) either in a supine, in a 15 degrees head-up tilt or in a 15 degrees head-down tilt position. Measurements of ITBV and hemodynamics by the double indicator method were recorded after induction of anesthesia and application of a fluid bolus (Lactated Ringer's solution 10 ml/kg), after positioning and after induction of pneumoperitoneum. RESULTS: Intrathoracic blood volume index (ITBVI) increased significantly after induction of pneumoperitoneum in all body positions (supine: from 18.5 +/- 3.3 -20.2 +/- 5.2 ml/kg (+6%) head-up from 16.7 +/- 3.8 - 17.4 +/- 3.7 ml/kg (+16%) and head-down: from 19.8 +/- 5.6 - 20.5 +/- 5.9 ml/kg (+14%)). Heart rate did not change significantly in any of the groups. Cardiac index showed a statistically significant change in the head-down position with pneumoperitoneum (-11%). A good correlation was found for stroke volume (SV) with ITBV (r = 0.79), but not with central venous pressure (r = 0.26). Systemic vascular resistance index increased significantly in all three groups (supine +6%, head-up +16%, head-down position +14%). CONCLUSION: The present study indicates that the onset of pneumoperitoneum, even with moderate intra-abdominal pressures, is associated with an increased intrathoracic blood volume in ASA I/II patients.     

Effect of 2 liters of intraperitoneal dialysate on the cardiovascular system

In 21 patients receiving continuous ambulatory peritoneal dialysis (CAPD), the effect of 2 liters of intraperitoneal dialysate on the supine and upright hemodynamics (19 patients), and the hemodynamic responses to 45 degrees head-up tilt (9 patients) were studied. Blood pressure (BP), heart rate (HR) and stroke volume (SV) (using impedance cardiography) were measured. In the supine position there was no significant difference in BP, SV, HR, derived cardiac output (CO) and peripheral resistance (PR) between "empty" (E) and "full" (F) conditions. On standing in both E and F conditions there were significant falls in systolic BP (p less than 0.001, compared with supine), SV and CO (p less than 0.05) accompanied by an increase in HR (p less than 0.001) but no significant change in peripheral resistance nor diastolic BP. The fall in systolic BP was greater in the E condition (from 149.3 +/- 4.5 mmHg to 134.6 +/- 5.9 in E, from 148.8 +/- 4 mmHg to 140.8 +/- 5.0 in F, p less than 0.001) and was accompanied by a bigger rise in HR (from 80.2 +/- 4.3 beat/min to 91.8 +/- 5.3 (E), from 79.4 +/- 4.4 to 87.7 +/- 5.2 (F, p less than 0.001). On tilting in 13 normal subjects there was an increase in diastolic BP (76.7 +/- 2.0 mmHg to 81.4 +/- 0.6, p less than 0.01), HR (63.3 +/- 2.4 beat/min to 73.6 +/- 1.0, p less than 0.01) and PR (13.4 +/- 1.0 mmHg/l/min to 21.3 +/- 0.2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiac output and the recumbent position in late pregnancy

Changes in cardiac output were measured by transcutaneous aortovelography in 30 pregnant patients and in 30 control subjects with change of position from the supine. When compared to the supine position, the left and right lateral and left 15 degrees tilt positions caused statistically significant increases in cardiac output, whereas the right 15 degrees tilt position did not. Neither fetal head engagement nor the time spent in each position had significant effects on the changes in cardiac output. It was not possible to identify a subgroup of pregnant patients who were particularly sensitive to changes in posture.     

Does targeted pre-load optimisation by stroke volume variation attenuate a reduction in cardiac output in the prone position

The prone position can reduce cardiac output by up to 25% due to reduced preload. We hypothesised that preload optimisation targeted to stroke volume variation before turning prone might alleviate this. A supine threshold stroke volume variation of 14% in a preliminary study identified patients whose cardiac outputs would decline when turned prone. In 45 patients, cardiac output declined only in the group whose supine stroke volume variation was high (mean (SD) 5.1 (2.0) to 3.9 (1.9) l.min(-1) ; p < 0.001), but not in patients in whom it was low, or in those in whom stroke volume variation was high, but who received volume preload (p = 0.525 and 0.941, respectively). We conclude that targeted preload optimisation using a supine stroke volume variation value < 14% is effective in preventing falls in cardiac output induced by the prone position.     

Relationship between stroke volume, cardiac output and filling of the heart during tilt

Background: Cardiac function curves are widely accepted to apply to humans but are not established for the entire range of filling of the heart that can be elicited during head-up (HUT) and head-down tilt (HDT), taken to represent minimal and maximal physiological filling of the heart, respectively. With the supine resting position as a reference, we assessed stroke volume (SV), cardiac output (CO) and filling of the heart during graded tilt to evaluate whether SV and CO are maintained during an assumed maximal physiological filling of the heart elicited by 90° HDT in healthy resting humans.
Methods: In 26 subjects, central blood volume was manipulated with graded tilt from 60° HUT to 90° HDT. We measured SV, CO (Finometer^®) and cardiac filling by echocardiography of the left ventricular end-diastolic volume (LVEDV; n =12).
Results: From supine rest to 60° HUT, SV and CO decreased 23 ml [confidence intervals (CI): 16–30; P <0.001; 23%] and 0.9 l/min (0.4–1.4; P <0.0001; 14%), respectively, but neither SV nor CO changed during HDT up to 70°. However, during 90° HDT, SV decreased 12 ml (CI: 6–19; P <0.0001; 12%), with an increase of 21 ml (9–33; P =0.002; 16%) in LVEDV because HR increased 3 bpm and CO decreased 0.5 l/min (ns).
Conclusion: This study confirmed that SV and CO are maximal in resting, supine, healthy humans and decrease during HUT. However, 90° HDT was associated with increased LVEDV and induced a reduction in SV.     

Systemic circulation and cerebral oxygenation during head-up tilt in spinal cord injured individuals

OBJECTIVE: To compare tilt-induced alterations in cardiovascular homeostasis and cerebral oxygenation of spinal cord-injured (SCI) to able-bodied (AB) individuals. DESIGN: Subjects underwent 10 min supine rest followed by 10 min 70 degrees head-up tilt. The last 5 min of supine rest and head-up tilt were analyzed, provided a steady state existed. SUBJECTS: SCI individuals (n= 11), with lesions between C4 and T4, and AB individuals (n= 10), all males and balanced for age and weight. MAIN OUTCOME MEASURES: Calf circumference, mean arterial pressure (MAP), stroke volume, heart rate and cerebral oxygenated ([O2Hb]), deoxygenated ([HHb]) and total ([tHb]) haemoglobin concentration changes were measured. RESULTS: Head-up tilt evoked a greater fall in MAP (mean (SD): -9 (12) vs 2 (6) mmHg P=0.02) and stroke volume (-43 (12) vs -22 (10)%, P=0.005), and a greater increase in heart rate (27 (12) vs 18 (6) beats, P=0.04) in SCI than AB. Cardiac output decreased during head-up tilt in SCI but not in AB (-17 (15) vs 1 (15)%, P=0.01). The change in cerebral oxygenation ([HHb]: 3.9 (2.8) vs 2.8 (1.4) micromol x l(-1), P=0.1 and [O2Hb]: -6.1 (5.0) vs -2.1 (5.5) micromol x l(-1), P=0.1) was similar in SCI and AB. All variables mentioned showed a change significantly different from zero in both groups, apart from [O2Hb] in AB and [tHb] in both groups. CONCLUSION: SCI demonstrated a greater decrease of MAP and stroke volume with a similar decrease in cerebral oxygenation compared to AB. This suggests that although systemic circulation was less well regulated in SCI compared with AB, cerebral circulation in SCI was maintained as in AB.     

Hemodynamic changes due to Trendelenburg positioning and pneumoperitoneum during laparoscopic hysterectomy

More prolonged gynecological laparoscopic operations are being performed in recent years, and a steeper head-down position is required. The early reports of hemodynamic changes during gynecologic laparoscopy are conflicting, and the effects of anesthesia, head-down tilt and pneumoperitoneum have not been clearly separated. Invasive hemodynamic monitoring was carried out in 20 female ASA Class I-II patients who underwent laparoscopic hysterectomy. Baseline measurements were made in the supine, supine-lithotomy and Trendelenburg (25 30 degrees) positions in awake patients. Measurements were repeated in the supine-lithotomy and Trendelenburg positions after induction of anesthesia, during laparoscopy 5 minutes after the beginning of peritoneal CO₂-insufflation (intra-abdominal pressure 13–16 mmHg) and at 15-minute intervals thereafter, after laparoscopy in the Trendelenburg and supine positions, after extubation and in the recovery room at 30-minute intervals. Patients received balanced general anesthesia with isoflurane in 35% O₂ in an oxygen/air mixture. End tidal PGO₂ was maintained between 4.5–4.8 kPa (33—36 mmHg) by changing the minute volume of controlled ventilation. The Trendelenburg position in awake and anesthetized patients increased pulmonary arterial pressures (PAP), central venous pressure (GVP) and pulmonary capillary wedge pressure (PCWP). These pressures increased further at the start of CO₂-insufflation, decreased towards the end of the laparoscopy and reached pre-insufflation levels after deflation of pneumoperitoneum. The mean arterial pressure (MAP) increased at the beginning of laparoscopy in comparison with the pre-laparoscopic values. Heart rate (HR) was quite stable during laparoscopy. The cardiac index (CI) decreased with anesthesia from 3.8 to 3.2 1 · min^-1 · m^-2 and further during laparoscopy to 2.7 1 · min^-1 · m^-2, returning to pre-insufflation values soon after deflation. The stroke index (SI) changed in concert with the GI changes. The right ventricular stroke work index decreased during laparoscopy more than the left ventricular stroke work index. The right atrial pressure (GVP) exceeded the PCWP more often during laparoscopy than during any other phase of the procedure. Anesthesia and the Trendelenburg position increased the CVP, PCWP and pulmonary arterial pressures and decreased cardiac output. Pneumoperitoneum increased these pressures further mostly in the beginning of the laparoscopy, and cardiac output decreased towards the end of the laparoscopy. The risk of systemic CO₂-embolus was increased during laparoscopy.     

Influences of bilateral endoscopic transthoracic sympathicotomy on cardiac autonomic nervous activity.

OBJECTIVES: Endoscopic transthoracic sympathicotomy (ETS) is a minimal invasive procedure of thoracic sympathetic blockage. The purpose of this study was to evaluate cardiac autonomic nervous activity after ETS in order to confirm the reliability and safety of ETS. METHODS: A series of electrophysiological studies were performed before and 1 week after bilateral 2nd and 3rd thoracic sympathicotomy in 13 patients with primary palmar hyperhydrosis. Palmar perspiration was measured under sympathetic stress, and body surface mapping was recorded in a supine position. In the head-up tilt test of 0, 30, 60 and 90 degrees, corrected QT interval (QTc) and T wave amplitude (Twa) were assessed. The power spectral analysis of heart rate variability was processed to attain power values of the low-frequency (0.04-0.15 Hz), the high-frequency (0.15-0.40 Hz) and the low/high frequency ratio. RESULTS: In all patients, the perspiration response on the palm to sympathetic stimulation was completely inhibited after ETS. Isointegral mapping revealed that ETS altered electroactivity on the heart. In the head-up tilt study, R-R intervals significantly increased after the surgery in the head-up tilt positions (P < 0.05), although there was no significant difference in the supine position. There is no significant difference in QTc and Twa before and after the surgery, both in the supine and the head-up tilt positions. There was no significant difference in the LF or HF before and after surgery, either in the supine position or the head-up tilt positions. In the LF/HF, there was no significant difference before and after surgery in the supine position. However, the LF/HF in the head-up tilt positions was significantly decreased after surgery (P < 0.05). Sympathetic suppression of ETS was recognized more obviously under the steeper head-up tilt positions. CONCLUSIONS: The influences on the cardiac autonomic nerve system of the ETS of upper thoracic sympathetic nerve were seen to be of a lesser degree at rest. However, the response to sympathetic stimulation was suppressed after the surgery.     

The effects of inflation of antishock trousers on hemodynamics in normovolemic subjects

Antishock trousers may maintain mean arterial pressure in trauma patients by increasing central blood volume and cardiac output. Hemodynamics, end-diastolic volume, stroke volume, cardiac output, and blood pressure were recorded in eight supine, healthy men in antishock trousers using two-dimensional echocardiography. Two inflation protocols were used. The antishock trousers were inflated to 50 and 100 mm Hg in a random fashion and inflation was maintained for 30 minutes before deflation. End-diastolic volume and blood pressure rose significantly (p less than 0.05) after antishock trouser inflation of 50 and 100 mm Hg. With the 50 mm Hg inflation, the stroke volume and end-diastolic volume fell below baseline over time. This did not occur with the 100 mm Hg inflation. After suit deflation, the stroke volume, end-diastolic volume, and cardiac output increased with 50 mm Hg inflation. The study shows that the antishock trousers alter several hemodynamic parameters. With lower inflation pressures, antishock trousers cause an increase in arterial pressure by increasing peripheral resistance. At higher inflation pressures, the antishock trousers increase cardiac output and as the cardiovascular system adjusts, maintain the pressure by increasing peripheral resistance.     

Hemodynamic consequences of high- and low-pressure capnoperitoneum during laparoscopic cholecystectomy

Background: Peritoneal insufflation to 15 mmHg diminishes venous return and reduces cardiac output. Such changes may be dangerous in patients with a poor cardiac reserve. The aim of this study was to investigate the hemodynamic effects of high (15 mmHg) and low (7 mmHg) intraabdominal pressure during laparoscopic cholestectomy (LC) Methods: Twenty patients were randomized to either high- or low-pressure capnoperitoneum. Anesthesia was standardized, and the end-tidal CO₂ was maintained at 4.5 kPa. Arterial blood pressure was measured invasively. Heart rate, stroke volume, and cardiac output were measured by transesophageal doppler. Results: There were 10 patients in each group. In the high-pressure group, heart rate (HR) and mean arterial blood pressure (MABP) increased during insufflation. Stroke volume (SV) and cardiac output were depressed by a maximum of 26% and 28% (SV 0.1 > p > 0.05, cardiac output p > 0.1). In the low-pressure group, insufflation produced a rise in MABP and a peak rise in both stroke volume and cardiac output of 10% and 28%, respectively (p < 0.05). Conclusions: Low-pressure pneumoperitoneum is feasible for LC and minimizes the adverse hemodynamic effects of peritoneal insufflation. Received: 23 May 1997/Accepted: 11 March 1998     

The effects of pneumoperitoneum and patient position on hemodynamics during laparoscopic cholecystectomy

BACKGROUND: The purpose of this study was to prospectively examine the combined effects of pneumoperitoneum and the reverse Trendelenberg position on cardiac hemodynamics during laparoscopic cholecystectomy. METHODS: Thirty-nine patients undergoing laparoscopic cholecystectomy as performed by a single surgeon were enrolled in the study. Hemodynamic data were collected continuously using a transthoracic bioimpedance monitor. All patients were subjected to insufflation pressures of 15 mmHg. Data were examined using mixed analysis of variance (ANOVA). RESULTS: Cardiac index fell 11% with induction of anesthesia (p < 0.05), with stroke volume decreasing 7.2% (p < 0.05). Insufflation caused significant decreases in stroke volume (SV) left ventricular end diastolic volume (LVEDV) but not cardiac index (CI). Placing the patients in the reverse Trendelenberg position caused no significant changes in these parameters. There were no significant differences between ASA (American Society of Anesthesiologists) classes I and II patients when compared to ASA III patients. CONCLUSIONS: Patients undergoing laparoscopic cholecystectomy experience significant hemodynamic depression. The effect of general anesthesia is the most profound. Insufflation of the abdomen caused more mild hemodynamic effects in our study. The addition of a reverse Trendelenberg position did not alter the patient's hemodynamic status.     

Hemodynamic effects of lysine-vasopressin in orthostatic hypotension

Previous investigations have demonstrated that the postural stimulation of arginine vasopressin (AVP) release is reduced in patients with Shy-Drager syndrome. We studied the effects of lypressin nasal spray on hemodynamic parameters in ten patients with chronic orthostatic hypotension. Heart rate, blood pressure, and stroke volume were measured at 0 degrees, 45 degrees and 70 degrees tilt before and one-half hour after two nasal sprays (four United States Pharmacopeia posterior pituitary pressor units, 7.4 micrograms) of lypressin. Lypressin did not significantly alter the effect of tilt on heart rate, stroke volume, and cardiac output but increased the blood pressure and total peripheral resistance. AVP analogues should be tested for treating chronic postural hypotension.     

Continuous transesophageal echo-Doppler assessment of hemodynamic function during laparoscopic cholecystectomy

STUDY OBJECTIVE: The objective of this study was to examine the utility of the transesophageal echo-Doppler device in evaluating hemodynamic changes during laparoscopic cholecystectomy. DESIGN: This was a prospective, controlled, observational open study. SETTING: The study took place in a university hospital. PATIENTS: Twenty patients with ASA physical statuses II and III undergoing laparoscopic cholecystectomy were enrolled into the study. INTERVENTIONS AND MEASUREMENTS: A standardized general anesthetic and surgical technique was used for all patients. Similar depth of hypnosis (using bispectral index monitoring) was maintained in all patients. Hemodynamic parameters including mean arterial pressure (MAP), cardiac index (CI), left ventricular (LV) ejection time interval indexed to the heart rate, maximum acceleration, peak velocity, and systemic vascular resistance (SVR) were recorded at predetermined intervals: before incision, after peritoneal CO(2) insufflation and head-up tilt, every 10 minutes thereafter, and after deflation of the abdomen and return to supine position. MAIN RESULTS: The transesophageal echo-Doppler probe placement was achieved in 3 to 5 minutes in all patients, and the probe position was maintained after creation of pneumoperitoneum and change in positioning. Induction of pneumoperitoneum and head-up tilt resulted in a significant increase in MAP and SVR (P < .05) that remained higher until deflation. The CI, LV ejection time interval indexed to the heart rate (a measure of LV filling), and maximum acceleration (a measure of contractility and global ventricular function) remained stable. CONCLUSIONS: The transesophageal echo-Doppler device can be used during laparoscopic cholecystectomy. The LV function, as determined by measurement of CI and maximum acceleration, was preserved during laparoscopic cholecystectomy despite significant increases in afterload (ie, MAP and SVR).     

Hemodynamic changes during laparoscopic cholecystectomy monitored with transesophageal echocardiography

Although pneumoperitoneum has been well tolerated in a predominantly healthy population, there is concern that an increased intraperitoneal pressure may be poorly tolerated in patients with marginal cardiopulmonary function. The purpose of this study was to demonstrate noninvasively the hemodynamic effects of carbon dioxide pneumoperitoneum utilizing biplane transesophageal echocardiography.Fourteen otherwise-healthy patients undergoing nonemergent laparoscopic cholecystectomy were studied using bi-plane transesophageal echocardiography under a standardized anesthetic protocol utilizing isoflurane, fentanyl, and vecuronium bromide. Endtidal CO₂, oxygen saturation, cardiac rhythm, temperature, and blood pressure were monitored noninvasively. Minute ventilatory volume was adjusted as needed to keep end-tidal CO₂ less than 38 mmHg. Data were recorded at baseline, following abdominal insufflation to 15 mmHg with CO₂, with head-up tilt of 20°, following exsufflation, and with the patient level. Significance was determined using a paired Student t-test.Insufflation to 15 mmHg decreased cardiac index (C.I.) by 3% (3.34 to 3.23 l/min/m²) while both heart rate (HR) and mean arterial pressure (MAP) increased (by 7% and 16%), respectively, and stroke volume index decreased by 10% (from 51.6 to 46.6 ml/beat/m²). Head-up tilt of 20° further decreased CI to 2.98 l/min/m² (–11%) and SVI to 40.3 ml/beat/m² (–22%) while HR increased by a total of 14% and MAP by 19%.As laparoscopic techniques are applied to a broader population, the impact of small but significant decrements in cardiac function become increasingly important. This study demonstrates that the combination of CO₂ pneumoperitoneum and the reverse Trendelenburg position does adversely effect cardiac output.Presented at the annual meeting of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES), Nashville, Tennessee, USA, 18–19 April 1994     

PULMONARY GAS EXCHANGE DURING DELIBERATE HYPOTENSION

Respiratory physiological deadspace may increase from 35 percent of the tidal volume in the normal anaesthetized, normotensiveand supine patient to as much as 80 per cent in the hypotensivepatient in the head-up tilt. Increased mean airway pressure,hypotension, sudden head-up tilt or maintenance of tilt, alltend to increase the respiratory deadspace. Arterial and end-tidalPco² differences parallel the deadspace changes. The averagePco² difference in the supine normotensive patient was 9 mmHg, but during maintained head-up body tilt during hypotension,this difference increased to as much as 25 mm Hg. These dataemphasize the need for careful control of respiration, withhigher than normal tidal volumes and oxygen concentrations duringdeliberate hypotension. They are equally applicable to otherhypotensive states including shock