Influence of pneumoperitoneum and patient positioning on respiratory system compliance.

STUDY OBJECTIVE: To investigate the influence of pneumoperitoneum (PP) and posture on respiratory compliance and ventilation pressures. DESIGN: Prospective, single blind trial. PATIENTS: 10 female ASA physical status I and II patients scheduled for elective gynecologic laparoscopy. SETTING: University medical center. INTERVENTIONS: Anesthesia was performed as total IV anesthesia (TIVA) with propofol, alfentanil, and atracurium. After induction of anesthesia and orotracheal intubation, the lungs were ventilated to maintain partial pressure of CO(2) (P(ET)CO(2)) of 30 +/- 3 mmHg. Ventilation was kept constant. As gas mixture oxygen and air 1:1 was used without positive end-expiratory pressure (PEEP). MEASUREMENTS: Measurements were taken before and after creation of pneumoperitoneum with an intraabdominal pressure (IAP) of 10 mmHg, of 15 mmHg in 20 degrees head-down tilt, then in 20 degrees head-up tilt, and after deflation of PP. We determined peak inspiratory pressure (PIP), mean airway pressure (mPaw), P(ET)CO(2), expiratory minute volume (V(E)), heart rate (HR), and systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP). Respiratory system compliance (C(eff rs)) was calculated as quotient of tidal volume (V(T)) and PIP. MAIN RESULTS: After creation of PP (IAP 10 mmHg), there was a significant increase of median PIP (3 cmH(2)O), mPaw (1 cm H(2)O) and arterial pressure (BP), (MAP by 7 mmHg), C(eff rs) decreased by 6 mL. cm H(2)O(-1). Increase of IAP to 15 mmHg led to a further increase of PIP (2 cm H(2)O) and mPaw (1 cm H(2)O), and a further decrease of C(eff rs) by 5 mL cm H(2)O(-1); BP decreased (MAP by 5.5 mmHg). Head-up or head down positions showed no significant hemodynamic or pulmonary changes. P(ET)CO(2)increased from 29.5 to 36 mmHg at an IAP of 15 mmHg, but then no further changes were noticed. Five minutes after deflation of pneumoperitoneum all values returned to baseline levels. CONCLUSIONS: Creation of PP at an IAP of 15 mmHg reduced respiratory system compliance, and increased peak inspiratory and mean airway pressures, which quickly returned to normal values after deflation. Head-down or head-up position did not further alter those parameters.

Intraoperative monitoring of the recurrent laryngeal nerve in 151 consecutive patients undergoing thyroid surgery.

IMPLICATIONS: We present a technique of intraoperative monitoring of the recurrent laryngeal nerve using a surface electrode attached to a routine endotracheal tube. The technique proved noninvasive, easy to use, and reliable in 151 prospective consecutive patients for preventing permanent laryngeal nerve damage in thyroid surgery.

Influence of pneumoperitoneum and patient positioning on preload and splanchnic blood volume in laparoscopic surgery of the lower abdomen.

STUDY OBJECTIVE: To determine the hemodynamic effects of pneumoperitoneum and patient positioning during laparoscopic surgery of the lower abdomen. DESIGN: Prospective study. SETTING: University-affiliated medical center. PATIENTS: 10 ASA physical I and II female patients scheduled for laparoscopic surgery of the lower abdomen. INTERVENTIONS: Patients were anesthetized with propofol and an alfentanil infusion, then intubated, and normoventilated. MEASUREMENTS: After intubation, a transesophageal multiplane probe for measurements of right (RVESA) and left (LVESA) ventricular end-systolic and end-diastolic areas (RVEDA and LVEDA) and ejection fraction area (RVEFa, LVEFa) was introduced; heart rate (HR) and noninvasive blood pressure (BP) were recorded every minute. Ventilation was not changed during the measurements. A transvaginal ultrasound probe was inserted to measure the diameter of the common iliac vein. Measurements were performed 15 minutes after induction of anesthesia and while patients were in the supine position (P 0), 10 minutes after CO(2) insufflation to 10 mmHg IA pressure (P 10), 10 minutes after a further increase to 15 mmHg (P 15), 10 minutes after 20 degrees Trendelenburg (P 15 T), and 20 degrees reverse Trendelenburg positions (P 15 RT). Data are shown as medians, 25th to 75th percentiles, and comparisons between P 0, P 10, P 15, and P15 T were made with the Friedman test, followed by Wilcoxon test, when significant. Data at P 15 T, P 15 RT, and P 15 were compared using the Wilcoxon test, with a p-value < 0.05 regarded as significant. MAIN RESULTS: Pneumoperitoneum at 10 mmHg abdominal pressure caused a significant increase of LVESA by 78% (RVESA: 61%) and LVEDA by 48.5% (RVEDA: 45%). The diameter of the common iliac vein was decreased by 6%. A further increase of abdominal pressure to 15 mmHg led to an additional increase of 20% (LVESA) and 17% (LVEDA). Mean arterial pressure increased by a significant 7% at P 10, decreasing subsequently by 5% at P 15. The Trendelenburg position did not alter any hemodynamic findings. Reverse Trendelenburg position, however, caused a significant LVEDA-and RVEDA-decrease by 18% and 27%, respectively, and an increase in the diameter of the common iliac vein by 22%. The LVEFa and RVEFa decreased significantly after abdominal CO(2) insufflation by 18% each (P 10) without further change. CONCLUSIONS: The lithotomy position and subsequent pneumoperitoneum increased preload, probably as a result of blood shifting from the abdomen to the thorax by compression of splanchnic vessels caused by the pneumoperitoneum. Careful fluid management, maintaining low abdominal pressure, and use of the reverse Trendelenburg position are favored to prevent adverse hemodynamic effects in laparoscopic surgery.

Comparison of a continuous glucose-insulin-potassium infusion versus intermittent bolus application of insulin on perioperative glucose control and hormone status in insulin-treated type 2 diabetics.

STUDY OBJECTIVE: To compare the effect of two different perioperative insulin management regimes on patients undergoing either major surgery (vascular surgery) or minor surgery (vitrectomy). DESIGN: Prospective, double-blind randomized trial. PATIENTS: 48 insulin-treated type 2 diabetics aged 18 to 85 years were studied. SETTING: University medical center. INTERVENTIONS: Patients were divided into four groups of 12 patients each: Groups A and B (major surgery), Groups C and D (minor surgery). Group A and C patients were treated with a continuous modified glucose-insulin-potassium infusion according to blood glucose levels after intubation. Patients assigned to Groups B and D were treated with intermittent intravenous (IV) insulin injections when glucose levels exceeded 12 mmol L(-1). MEASUREMENTS: Glucose and potassium levels were measured every 15 minutes and 30 minutes during surgery and up to 4 hours post-surgery. Plasma levels of lactate, cortisol, glycerol, and free fatty acids were measured in arterial samples after intubation (S1), after extubation (S2), and 4 hours after surgery (S3). MAIN RESULTS: There were no significant differences of the patient characteristics among the four groups. There was no significant difference in the time course of plasma glucose levels and hormone variables measured among the four groups. One episode of hyperglycemia in Group D during the postoperative period was treated with 12 IV units of insulin. One patient in Group A and one in Group B received potassium intraoperatively (15 and 29 mmoL, respectively). Postoperatively, two other patients of Group A received 19 and 12,5 mmoL, respectively, and one of Group B received 20 mmoL potassium. CONCLUSIONS: Both regimens resulted in relatively stable and comparable blood glucose levels throughout the perioperative period of the minor and major surgeries without differences in metabolic control as measured by levels of lactate, cortisol, glycerol and free fatty acids. Simplicity would favor the intermittent regimen to manage insulin treated type 2 diabetics.

The lumbar paravertebral region provides a novel site to assess neuromuscular block at the diaphragm.

PURPOSE: We evaluated a novel, paravertebral site for assessment of neuromuscular block at the diaphragm. The neuromuscular blocking effect of 0.1 mg x kg(-1) cisatracurium at the adducting laryngeal muscles, the diaphragm and the adductor pollicis (AP) were compared. METHODS: In 24 patients undergoing thyroid surgery, evoked responses from the adducting laryngeal muscles and the AP muscle were obtained using surface electromyography (EMG). Skin electrodes were placed paravertebrally near T12/L1 or L1/L2 (novel position; n = 12) or conventionally (n = 12). After stimulation of the recurrent laryngeal, phrenic and ulnar nerves, the lag, onset time and maximum effect were measured (0.1 Hz, single twitch) as well as the time to reach 25% of T1/T0 (T 25%) using train-of-four stimulation every 20 sec. RESULTS: A mean maximum block of more than 94% was reached at all sites. Lag, onset time and T 25% at the adducting laryngeal muscles and the diaphragm were significantly (P <0.005) shorter than at the AP muscle and did not differ significantly between the two diaphragmatic monitoring sites (conventional: 64 +/- 21 sec, 166 +/- 41 sec and 20 +/- 3 min vs novel: 60 +/- 16 sec, 161 +/- 40 sec and 22 +/- 2 min respectively). CONCLUSION: Onset and duration of action of 0.1 mg x kg(-1) cisatracurium was shorter at the larynx and the diaphragm than at the AP muscle. EMG results obtained from the novel, paravertebral site did not differ from the conventional monitoring site at the seventh or eighth intercostal space and suggest this alternative site is appropriate for monitoring of the diaphragm.

Intraoperative monitoring of the recurrent laryngeal nerve during single-lung ventilation in esophagectomy.

IMPLICATIONS: We describe the use of a surface electrode attached to a double-lumen endobronchial tube to identify and monitor the recurrent laryngeal nerve during esophagectomy in single-lung ventilation. The technique is demonstrated in the case of a patient with carcinoma of the distal esophagus.

Surface vs intramuscular laryngeal electromyography.

PURPOSE: To compare surface and intramuscular laryngeal electromyography (EMG) with adductor pollicis muscle EMG after 0.1 mgxkg(-1) cisatracurium. METHODS: This prospective study included ten patients undergoing surgery with risk of damage to the recurrent laryngeal nerve (RLN). The tracheas were intubated after fentanyl/propofol without the aid of muscle relaxation. A surface laryngeal electrode was attached to the tube and placed amidst the vocal cords; two straight needles were inserted endoscopically into the left lateral cricoarytenoid muscle. Single twitch stimulation of the left RLN (0.1 Hz) was performed transcutaneously; skin EMG of the left adductor pollicis muscle was performed at 0.1 Hz. After supramaximal stimulation for 10 min, 0.1 mgxkg(-1) cisatracurium was injected. Lag, onset time and peak effect were measured and compared. RESULTS: Good correlation (r = 0.9, 0.8, P < 0.005) and good comparability of the two methods of laryngeal EMG (mean difference and limits of agreement: 0 +/- 28 sec for lag time, -2 +/- 84 sec for onset time) was shown. The mean surface laryngeal lag and onset times were 67 +/- 22 sec and 198 +/- 72 sec, compared with the adductor pollicis muscle (98 +/- 30 sec and 242 +/- 59 sec) at P < 0.01. Peak effects at larynx (92 +/- 9%) and adductor pollicis muscle (95 +/- 3%) were similar. CONCLUSION: Surface laryngeal EMG is comparable to intramuscular laryngeal EMG to determine degree and onset of the neuromuscular blockade. Increasing muscle relaxation does not cause the surface electrode to lose contact with the vocal cords and therefore underestimate onset time and peak effect.

Moderate controlled hypotension with sodium nitroprusside does not improve surgical conditions or decrease blood loss in endoscopic sinus surgery.

UNLABELLED: STUDY OBJECTIVES To determine if moderate controlled hypotension can improve the dryness of the surgical field in endoscopic sinus surgery. STUDY DESIGN: Randomized, prospective study. SETTING: University-affiliated hospital. PATIENTS: 32 ASA physical status I and II adult patients undergoing endoscopic sinus surgery. INTERVENTIONS: All patients were premedicated orally with chlorazepate. Patients in Group H received 12.5 mg captopril orally prior to surgery. Anesthesia was provided using an intravenous (IV) technique supplemented with nitrous oxide (N(2)O); anesthesia was maintained with boluses of 2 mcg/kg fentanyl and a propofol infusion at rates between 3 and 9 mg/kg/h at the discretion of the anesthetist. In Group H, sodium nitroprusside was infused at a rate of 1 to 2.5 mcg/kg/min to maintain moderate controlled hypotension with mean blood pressure of 65 to 75 mm Hg. MEASUREMENTS AND MAIN RESULTS: Arterial blood pressure was assessed via the radial artery. Readings were recorded prior to intubation, immediately after intubation, at the start of surgery, then at 5, 15, 30, 45, and 60 minutes intraoperatively, and at the end of surgery. Intraoperative blood loss, dryness of the surgical field, adrenocorticotropic (ACTH) hormone, arginin-vasopressin (AVP), cortisol, and the preoperative and postoperative psychomotoric function were examined. At the start of surgery and thereafter, MAP increased in Group N but not in Group H. Throughout surgery, MAP was significantly lower in Group H than in Group N. Blood loss, dryness of the surgical field, ACTH, AVP, and cortisol levels, and psychomotoric function were not significantly different between the groups. CONCLUSION: Intravenous anesthesia supplemented with N(2) is as effective as moderate controlled hypotension when blood loss, visibility in the surgical field, ACTH, AVP, and cortisol are examined.

Determination of eicosanoid and cytokine production in salvaged blood, stored red blood cell concentrates, and whole blood.

STUDY OBJECTIVE: To determine the production of the eicosanoids prostaglandin 2 (PGE2) and thromboxane 2 (TxB2) and the cytokines interleukin 1 beta (IL-1-beta) and interleukin 6 (IL-6) in whole blood (WB), unfiltered red blood cell (RBC), and filtered RBC concentrates, and salvaged blood. DESIGN: Prospective study. SETTING: University hospital of Erlangen. PATIENTS: 32 healthy volunteers and 14 ASA physical status I, II, and III radical prostatectomy patients (mean age 65 yrs). INTERVENTIONS: Sixteen WB units and 16 RBC units (divided into 16 filtered and unfiltered units each) were taken from 32 volunteers. Fourteen salvaged RBC units were obtained from the 14 radical prostatectomy patients. Sixteen WB units were stored for 35 days. From the 16 WB donations, RBC concentrates (PAGGS-M) were prepared. The RBC concentrates were halved, one half had its leukocytes removed at day 0; both halves were stored for 49 days. Salvaged blood (n = 14) was stored up to 2 hours during surgery and then retransfused. MEASUREMENTS AND MAIN RESULTS: Immediately at the start of the study, in all blood units (WB, RBC filtered, and RBC unfiltered units) at days 0 and 21, and at the end of the storage period (WB: 35 days, RBC concentrates: 49 days) and in the salvaged RBC units, the following parameters were measured: PGE2, TxB2, IL-1-beta, IL-6, hematocrit, platelet number, leukocytes, blood volume, and hemoglobin. During storage, different levels of PGE2, TxB2, IL-1-beta, IL-6 for WB, filtered RBC concentrates, and unfiltered RBCs were found. The higher levels of PGE2, TxB2, IL-1-beta, and IL-6 were found in the WB and RBC salvaged units than the filtered RBCs or unfiltered RBC units. There was no statistically significant difference between WB and salvaged RBCs. Higher levels of leukocytes and platelets were found in WB units and salvaged RBCs as compared to filtered or unfiltered RBCs. CONCLUSIONS: The eicosanoid and cytokine levels in the salvaged, filtered RBC, unfiltered RBC, and WB units stayed within physiological limits, suggesting that these levels do not contribute to the risk of nonhemolytic, immunomodulated transfusion reactions, even in massive transfusions.