ANESTHESIA FOR LAPAROSCOPIC GENERAL SURGERY*
A special review
Mohammad Said Maani Takrouri MB. CHB. FFARCS(I)
Department of Anesthesia ,
COLLEGE OF MEDEICINE, KING SAUD UNIVERSITY
King Khalid University Hospital (KKUH)
* Based on a lecture delivered at the 5th Pan Arab Congress on Anaesthesia, Intensive Care and Pain relief. Cairo. Egypt 9-12th Dec. 1997.
Also appeared in abstract form in Newsletter of Saudi Anaesthetic Association vol. 8, (1): 5-7,1998
Running title: ANESTHESIA FOR LAPAROSCOPIC SURGERY
Address for correspondence:
Dr. M.S.M. Takrouri, MB. ChB. FFARCS (I)
Professor of Anesthesia
Department of Anesthesia, King Khalid University Hospital (KKUH)
Riyadh 11461 P.O. Box 2925
Tel 009661 4671595
ABSTRACT: Laparoscopy employs highly technical equipment, and the surgeon needs special training in the technique. He masters in-depth knowledge of the use of optics, electrical principles, gas under pressure, and the physiologic changes that occur when carbon dioxide is placed in the abdominal cavity. Above all, the surgeon must adhere rigidly to guidelines for appropriate technique. deviation will most assuredly result in complications and even death. General surgery application of laparoscopy followed a wealth of medical experience from gynaecological laparoscopies, which declared the technique as safe, reduce hospital stay with little pain and disfigurement and laparoscopic cholecystectomy started to enjoy ever increasing popularity. It retained the advantages of shorter hospital stay, more rapid return to normal activities, less pain, small incisions and less postoperative ileus compared with the traditional open cholecystectomy. Soon many procedures were done using this new technique in adult and children. Anesthesia for laparoscopy has been established with a broad usage of agents an techniques. General anesthesia using balanced anesthesia technique including intravenous induction agents like: thiopentone, propofol, etomidate, and inhalational agents like: nitrous oxide, isoflurane, desflurane has been reported. variety of muscle relaxants including succinyl choline, mivacurium, atracurium, vecuronium aiming at rapid recovery and cardiovascular stability. Total intravenous anesthesia using agents like propofol, midazolam and ketamine, alfentanil and vecuronium has been reported also for outpatient laparoscopy. Epidural anesthesia was considered as safe alternative to general anesthesia for outpatient laparoscopy without associated respiratory depression. As for pain relief is concerned, many methods have been used. The pain mechanism is variable and analgesia requirment is less than those of open surgery. Cited complications include pneumothorax, cardiovascular collapse, surgical emphysema and pneumo-peritoneum complications. Among the implication for anaesthesia care, the importance of preoperative monitoring, careful positioning and observation during the insufflation of carbon dioxide. The drive to have short term admission to hospital would make it imperative to use short acting rapidly eliminated anaesthetic drugs, avoidance of vomiting and pain by proper use of modern anti-emetics and NSAID to help in avoidance of narcotics or reduction of the requirement.
Key words: Laparoscopy, General surgery, Anaesthesia, pain relief, monitoring.
INDUCED RESPIRATORY CHANGES
6. MONITORING DURING LAPAROSCOPY
7. COMPLICATIONS DUE TO LAPAROSCOPY
8. PAIN RELIEF
9. LAPAROSCOPY IMPLICATIONS FOR ANESTHESIA
Laparoscopy (Greek: l a p a r a = flank or l a p a r o s = soft; s k o p h i n = to look). It is a relatively modern procedure, it involves the insufflation of the abdomen by a gas, so the endoscope can visualise the intra-abdominal contents without being in direct contact with the viscera or tissues 1. It started as a gynaecological procedure in the mid fifties of the present century and developed into other surgical specialities and targeted more sick patients 2. General surgery application of laparoscopy followed a wealth of medical experience from gynaecological laparoscopies, which declared the technique as safe, reduce hospital stay with little pain and disfigurement and laparoscopic cholecystectomy started to enjoy ever increasing popularity. It retained the advantages of shorter hospital stay, more rapid return to normal activities, less pain, small incisions and less postoperative ileus compared with the traditional open cholecystectomy 3,4. Soon many procedures were done using this new technique in adult and children 5-7, hiatal hernia repair8, cervical dissection of oesophagus 9, diaphragmatic repair 10, gastroplasty 11, pheochromocytoma 12,13 and adrenalectomy 14 and others. More sick and older patients are subjected to this technique. Even laparascopy for cholecystectomy in patient with mythenia gravis and transplanted heart were reported 15,16. Many reviews discussed the issue we can indicate in particular those of Cali RW (1980)17 which dealt with technique, Cunningham AJ (1993)18 which dealt with the anaesthetic management and Alexander JI (1997)1 on pain relief in laparoscopic surgery. The aim of this review is to give an update and to summarise the current issue of laparoscopic surgery.
Anaesthesia during the procedure is more technically demanding, this is due to many factors. On one hand the technique itself introduces some trespassing on the respiratory and cardiovascular systems of the patients, and on the other it was introduced as safe and simple surgery which may be performed on outpatient basis hence demanding extreme caution in regard the anaesthetic technique which may respond positively to this expectation 19.
2. THE SURGEON AND HIS TECHNIQUE:
The procedure employs highly technical equipment, needs special training and special knowledge of the use of optics, electrical principles, gas under pressure, and the physiologic changes that occur when carbon dioxide is placed in the abdominal cavity. Above all the surgeon must adhere rigidly to guidelines for appropriate techniques. Deviation will most assuredly result in complications and even death. 17.
Early experience with laparoscopy 1949-1977 has been reported in a study conducted through questionnaire. This included 263900 laparo-pelviscopies performed in Germany and information was gathered from 380 respondents. There were 949 (3.56%) complications. 690 (2.59%) laparotomy. 24 (0.09%) burn or injury. Mortality was one death/11000 pelviscopy. 13 death (0.09) in 140977 (53%) diagnostic procedures. 3 death (0.08%) in 37639 (14.2%) diagnostic-operative. 8 death (0.09%) in 87284 (32.8%) sterilisation's operations. Since 1974 no mortality has been registered 20.
Risk of laparoscopy was addressed in a survey of 100000 gynaecological cases. It was found that there were 194 severe complications over 20 years. 53 cardio-respiratory complications of which 15 were fatal. 122 instrument’s injuries or burns of which 4 were fatal. 18 variable complications. No statistical conclusion is possible because the figures are an approximation 21.
Open cholecystectomy mortality rate was reported to be 1.8% just before laparoscopy era in urban hospital. 1.53% mean mortality between 1952-1990 is quoted in a review of published series 22.
European experience with laparoscopic cholecystectomy reported in a review of 1236 cases in 7 centres involving 20 surgeons. It showed that 1191 procedures were completed. 45 converted to open procedures (3.6%) either due to technical difficulties n=33, onset of complication n=11 or instrument failure n=1. No death was reported in these series. Postoperative complications were 20 of 1203 (1.6%). Of which 9 cases requiring laparotomy. The incidence of bile duct damage was 4 of 1203. Median hospital stay 3 days (range 1-27). Median time to return to full activity after discharge 11 days (range 7-42 days) 23.
Open versus laparoscopic cholecystectomy argument was reported in an Irish study. In a 50 consecutive patients. It was stated in this study that laparoscopy took longer anesthesia time mean (sd) 155 ± (61) min. versus open cholecystectomy anesthesia time of 102 ± (31) min. P<0.001. Laparoscopy took shorter mean postoperative hospital stay mean ± (sd) 3.5 ± (1.5) versus open cholecystectomy hospital stay of 8.8 ± (3.2) days. P<0.001. Reduced mean cost mean ± (sd) Irish pounds 895 ± (376) versus open cholecystectomy cost of 2210 ± (822) pounds. P<0.001 24.
3. ADVANTAGES OF LAPAROSCOPIC SURGERY :
The advantages can be summarised as follow: Reduction of post-operative pain. Better cosmetic results. Quicker return to normal activities. Hospital stay is reduced resulting in overall reduction in medical cost 24,25. Less post operative pneumonia and wound infection 26. Other studies confirmed the reduced metabolic derangement after laparoscopic cholecystectomy 27 , interleukin-6 level 28 and better respiratory function. The plasma cortisol and catecholamine concentrations were not significantly different from open cholecystectomy 28-30. But the post operative pulmonary function tests are better after laparoscopic cholecystectomy 31.
4. SPECIAL CHARACTERS OF LAPAROSCOPIC GENERAL SURGERY:
It is performed on older patients and patients with acute surgical conditions as compared to minor gynaecological laparoscopic procedures and it is likely to be associated with higher incidence of peri-operative complications. This should be in mind when interpreting the results of the studies on this group of young fit women The major problems in general surgery patients are related to cardiovascular effect of pneumoperitonium, systemic carbon dioxide absorption, extra-peritoneal gas insufflation, venous gas embolism and unintentional injuries to intra-abdominal structures 25.
5. PHYSIOLOGICAL CHANGES
5.1.1 INDUCED RESPIRATORY CHANGES:
The respiratory system can be affected by the following mechanisms: Effects of pneumoperitonium i.e. insufflation of the peritoneum by CO2. Effects of CO2 absorption. Diaphragmatic movement impairment. The effect of Trendelenberg or anti-Trendelenberg position needed during the procedure. Studies of the respiratory system during the procedure indicated many changes in normal function.
Creation of Pneumoperitoneum
Pneumoperitoneum creation involves the intraperitoneal insufflation of CO2 through a Veress needle while the patient is in Trendelenburg position. The potential physiological difficulties during creation of pneumoperitoneum are mainly cardiovascular and respiratory function derangement.
5.1.2 RESPIRATORY PARAMETERS
Respiratory Function. The available data suggest that the respiratory function changes occurring during laparoscopic cholecystectomy may differ from those reported during gynecologic laparoscopic procedures. In a study compared the ventilatory effects of laparoscopic cholecystectomy in 20 patients with normal cardiopulmonary status (ASA physical status I) to the ventilatory effects in 10 patients with documented cardiac and pulmonary disease (ASA status II and III). Although the patients without cardiopulmonary disease had increased end-tidal and PaCO2 and decreased arterial pH values after CO2 insufflation, these changes were not statistically significant. Similarly, no significant changes occurred in minute volume and peak inspiratory pressure after CO2 insufflation. In contrast, significant decreases in arterial pH and increases in PaCO2 were observed in patients with cardiopulmonary disease after CO2 insufflation. These patients also had minute ventilation and peak inspiratory pressures which were significantly higher than the baseline values after CO2 insufflation 32.
Early reports of laparoscopy during halothane anesthesia emphasised the dangers of hypercarbia when patients were allowed to breathe spontaneously. It was reported that the CO2 output (VCO2) increased from 135.4 1 2.5 ml.min-1 before, to 150.9 1 6.9 ml.min-1 after, the start of CO2 insufflation. This increased VCO2 was associated with end-tidal CO2 concentrations which increased from 4.7% to 5.4%. It was also observed the presence of tachypnea, increased minute ventilation, and respiratory acidosis in a study of 10 patients spontaneously breathing nitrous oxide/oxygen and 0.5% -1.0% halothane. The hypo- ventilation induced by the steep Trendelenburg position and the pneumoperitoneum-induced splinting of the diaphragm during halothane anesthesia which is potentially hazardous due to hypercarbia, acidosiss and cardiac arrhythmia. 18. In a trial using spontaneous respiration via mask and via endotracheal tubes compared to intubated ventilated patient, laparoscopy using isoflurane as the inhalational anaesthetic, it was found there were no significant hypercarbia, acidosis or cardiac arrhythmia 33,34.
5.1.3 CHANGES DURING INSUFFLATION OF THE PERITONEUM IAP OF 1.6 kPa.
In a study conducted on patients under total intravenous anaesthesia using propofol, and constant minute ventilation, the following changes were noted: Peak airway pressure increased by 50% during insufflation, and during exsufflation goes down to 37% of resting values. Plateau airway pressure increased by 81% - exsufflation 27%. Compliance of the respiratory system decreased by 47% - exsufflation 14% 35 . In another study on seven patients undergoing gynecological laparoscopy the effect of CO2 pneumo-peritonium and Trendelengburg was decreased total lungs capacity (TLC). And increased Pa CO2 and PACO2 36 . In another study comparing N2O and CO2 as insufflating gas in the group who received CO2 there were sharp rise in Pa CO2 and fall in pH, while no changes in those who received N2O (Mango R et al 1979)37. Although in a study, an increased physiological dead space, arterial to end tidal carbon dioxide partial pressure difference and high arterial partial pressure of carbon dioxide was found, it was not statistically significant 38.
A reduction in FRC relative to closing volume may be associated with the development of intraoperative atelectasis and intrapulmonary shunting. These changes may occur during general anesthesia because of a variety of factors: a) cephalad shift of the diaphragm associated with supine position; b) loss of inspiratory muscle tone; c) appearance of end-expiratory muscle tone in the abdominal expiratory muscles; d) changes in intrathoracic blood volume associated with induction of anesthesia; and e) influence of muscle relaxants on diaphragmatic excursion. The reduction in FRC associated with general anesthesia may be compounded by the CO2-induced pneumoperitoneum during laparoscopic cholecystectomy. A reduced cardiac output secondary to reduction in venous return or drug-induced myocardial depression may reduce mixed-venous O2 tension. Hypoxemia may be present when these changes are accompanied with reduction in the cardiac output 18.
5.1.4 THE EXTENT OF CO2 RESORPTION:
Respiratory minute volume increased in spontaneously breathing patients by 30-40% to maintain normo-carbia. CO2 output increased by 38% for 60 minutes after insufflation. D(a-A) CO2 showed no changes 39.
Elimination of CO2 was examined in patient subjected to gynaecology laparoscopy, laparoscopic cholecystectomy and pelviscopy under controlled ventilation. It was found that oxygen consumption (VO2) did not change but pulmonary elimination of CO2 (VECO2) and end tidal CO2 (ETCO2) continuee to rise from post insufflation till 8-10th minutes then a plateau was reached in the group of intraperitoneal insufflation, then it will continue to rise slowly throughout CO2 insufflation. It was concluded that CO2 diffuse to the body more during extra-peritoneal than intra-peritoneal, and it is not influenced by the duration of intra-peritoneal insufflation 40. It was shown to be affected by raising the intraperitoneal pressure above the venous vessels pressure which prevent CO2 resorption 41. The rate of CO2 re-absorption is 70 ml.min-1 during the first 30 minutes of pneumoperitoneum and latter of order of 90ml.min-1 42. The remaining CO2 in the body influence spontaneous respiration for 3 hours post operatively since there will be increase in respiratory rate (RR) to get ride of CO2 which may be prolonged in the presence of strong narcotics 43.
5.1.5 DIAPHRAGMATIC FUNCTION CHANGES:
Impaired diaphragmatic contractile function: This is manifested by the following: Maximal trans-diaphragmatic pressure is reduced by 50%. Maximal sniff manoeuvre pressure does not change. Tidal volume decreased by 30%. Inspiratory time/total cycle time reduced by 13% 44,45.
Dynamic respiratory pattern study after laparoscopic and open cholecystectomy showed small magnitude changes after laparoscopy, namely: Frequency of resting breathing increased by 29%, abdominal motion decreased by 32%, rib cage tidal volume increased by 70% and abdominal tidal volume decreased by 29%46.
5.1.6 Postoperative pulmonary function tests changes in 24 h form the pre-operative values:
In a study on 22 patients undergoing laparoscopic cholecystectomy, pulmonary function tests done before, 24 hours after and 1 week post-operatively showed the following results: FEV1 reduced to 75%. VC reduced to 73%. FRC reduced to 92%. TLC reduced to 82%. Inspiratory mouth pressure reduced to 66%. Expiratory mouth pressure reduced to 63%. PaO2 reduction. PaO2 no changes. Alveolar-arterial gradient increased 47.
5.2 Cardiovascular Effects.
Studies in healthy gynaecologic patients have consistently shown only minor hemodynamic changes during laparoscopic procedures with CO2 insufflation when intra-abdominal pressures (IAP) did not exceed 25 cm H2O (18 mm Hg). However, these short surgical procedures were performed in young, relatively healthy, female patients in the Trendelenburg position. Considering the widespread adoption of the laparoscopic cholecystectomy technique, there is a remarkable paucity of data concerning the hemodynamic changes induced by the CO2 pneumoperitoneum, both in healthy patients and in those with cardiopulmonary disorders. The initial use of gynecologic laparoscopy was associated with generation of IAP of up to 40 mm Hg (55 cm H2O). Modern laparoscopic cholecystectomy technology employs an electronic variable-flow insufflator, which automatically terminates flow when a preset IAP of 12 - 15 mm Hg is reached. Despite the relatively low IAP achieved, the volume of gas insufflated may exceed 50 L, because intra-abdominal gas may escape quickly through the multiple trocar/cannla puncture sites 18, 48- 50.
The extent of the cardiovascular changes associated with creation of pneumo-peritoneum will depend on the intra-abdominal pressure attained, the volume of CO2 absorbed, the patient's intra-vascular volume, the ventilatory technique, surgical conditions, and anesthetic agents employed. In a prospective, observational study of 16 otherwise healthy patients, no significant cardiac output changes, despite an increased mean arterial pressure and end-tidal CO2 (ETCO2) during creation of pneumoperitoneum. Similarly, other results reported no significant changes in cardiac output in a series of anesthetized, spontaneously ventilating patients in whom the IAP was 15-20 cm H2O (11-15 mm Hg). The effects of stepwise increases in IAP up to a maximum of 25 cm H2O in anesthetized, mechanically ventilated patients. At an IAP of 25 cm H2O, increases in airway pressure, intrathoracic pressure (ITP), CVP, and femoral venous pressure (FVP) were accompanied by hypertension, tachycardia, and increased (ETCO2) tension. Other researchers found that moderate increases of IAP (up to 25 cm H2O) may be accompanied by an increased effective cardiac filling pressure (defined as CVP-ITP), and therefore (according to Starling's law), by an increased cardiac output. When IAP was increased further to 40 cm H2O, tachycardia, hypotension, reduced CVP, and decreased cardiac output were observed. These changes were most marked in the horizontal compared with the head-down tilt position. It was speculated that increased IAP has two opposite effects on the cardiovascular system: it forces blood out of the abdominal organs and inferior vena cava and into the central venous reservoir, while at the same time it increases peripheral blood pooling and thus tends to decrease the central blood volume18, 48- 50.
The relative roles of the factors which contribute to changes in cardiac output may be difficult to separate, but the increased cardiac output at lower IAP may result from increased cardiac filling pressures, due partly to mechanical factors, and partly to sympathetically mediated constriction of capacitance vessels and hypercarbia-induced effects on cardiac efferent sympathetic activity. It was also reported a reduction in inferior vena caval blood flow and cardiac output of more than 60% when the IAP exceeded 40 mm Hg 18, 48- 50.
The effects of general anesthetics and intravascular volume on hemodynamic function during creation of pneumoperitoneum also have been investigated and reported : A 35% reduction in inferior vena caval blood flow and cardiac output of dogs when intraperitoneal insufflation of N2, N2O, and CO2 produced an IAP of 40 mm Hg during basal pentobarbital anesthesia. The combination of 1.0 minimum alveolar anesthetic concentration (MAC) of halothane plus hypovolemia (resulting from 15% blood volume loss) decreased the preinduction cardiac output more than either halothane anesthesia alone, or the induction of hypovolemia alone. Also in a study compared the hemodynamic effects of 2 kPa (15 mm Hg) IAP pressure to those due to a 30° Trendelenburg tilt in a prospective study of 16 mechanically ventilated patients, randomized to receive either halothane anesthesia or balanced anesthesia with meperidine and thiopental. Regardless of anesthetic technique, an IAP of 15 mm Hg or a 30° head-down tilt produced similar reductions in cardiac index which were accompanied by significant elevations in systemic vascular resistance. In addition to the above-mentioned mechanical effects induced by the pneumoperitoneum, other chemically induced cardiovascular effects of CO2 (such as arrhythmogenesis) has been observed 18, 48- 51.
5.2.1 CARDIOVASCULAR CHANGES WITH TRENDELENBERG POSITION & PNEUMOPERITONEUM
Cardiac output fall by 60% and there are no changes in heart rate 52. Moderate fall in stroke volume 53. Stroke index and cardiac index fall by 42% can be noticed. Total peripheral resistance increased by 100% in balanced anesthesia from 1620 to 2491 dyn.s. cm-5. M-2. 54.
5.2.2 HAEMODYMAMIC CHANGES WITH REVERSE TRENDELENBERG, LATERAL TILT AND PNEUMOPERITONIUM:
There is a decrease in mean arterial pressure and cardiac index., as well as increase in peripheral and pulmonary vascular resistance 49,50. These effects may be blunted by anaesthetic agents. There is also an increase in left ventricular end-systolic wall stress, and decreased left ventricular end-diastolic area but left ventricular ejection fraction was maintained during a study by trans-oesophageal echocardiography 55.
5.2.3 HAEMODYNAMIC CHANGES DURING LAPAROSCOPY WITH POSITIVE END-EXPIRATORY PRESSURE VENTILATION
On gynaecological patient for infertility the application of PEEP of 0.49 kPa (3.7 mmHg) was used with 25 degrees head down tilt. The intra-abdominal insufflation with CO2 was done using low pressure 0.7-1.1 kPa (5-8 mmHg). The net cardiac effects were small. But there were reduction in ETCO2, and there were no net increase in ETCO2 after CO2 insufflation 56.
6. MONITORING DURING LAPAROSCOPY
Routine intraoperative monitors as in other anaesthetics which includes EKG, pulse oximetry, blood pressure, pulse rate, ventilator performance, anesthetic gases concentration and patient’s temperature, There is need for a urinary bladder catheter and naso-gastric tubes to decompress the viscera and thus avoid injury to intra-abdominal contents during trocar insertion. For haemodynamically unstable or compromised patient and patients with cardio-respiratory chronic diseases careful monitoring of cardiovascular and blood gases is indicated 32. This also apply in case of obese patients 57. As for the question of blood gases, ETCO2 is most commonly used as a non-invasive substitute for PaCO2 in evaluating the adequacy of ventilation during laparoscopic surgery. However, ETCO2 may differ considerably from PaCO2 because of ventilation-perfusion (V/Q) mismatching, and erroneous clinical decisions may be reached if the two values are assumed to be equal, to change proportionally, or even to change in the same direction 58. In a study of healthy, mechanically ventilated patients undergoing laparoscopic cholecystectomy, equal and proportional increases in ETCO2 and PaCO2 were observed after CO2 insufflation . In this patient population, ETCO2 monitoring should suffice. In contrast, patients with preoperative cardiopulmonary disease demonstrated significant increases in PaCO2 and decreases in pH after CO2 insufflation, which were not reflected by comparable increases in ETCO2. The difference between PaCO2 and ETCO2 (P[a-ET]CO2) will increase if there is a greater contribution of ventilation from high V/Q regions. Therefore, radial artery cannulation for continuous blood pressure recording and frequent arterial blood gas analysis should be considered in patients with preoperative cardiorespiratory disease and in situations where intra-operative hypoxemia, high airway pressures, or elevated ETCO2 are encountered 18. In an investigation of pre and post CO2 insufflation on reading of ETCO2 of healthy patients, there was positive linear relationship between the maximum end-tidal carbon dioxide tension during laparoscopy with baseline value prior to carbon dioxide insufflation 59.
7. COMPLICATIONS DUE TO LAPAROSCOPY: In multi-centre study of complications of gynaecological laparoscopy reporting on 7604 procedures. There were one death, 2.76 per thousand complications requiring laparotomy; 4.46 per thousand for major surgical procedures and 0.42 per thousand for minor surgery and they are either intestinal injuries or less frequently vascular injuries 60, 61.
Other complications include: Reflex bradycardia due may be due to vagally-mediated reflex, and may be predisposed to by drugs like vecuronium, atracurium, halothane, fentanyl and succinylcholine. It can be overcome by anticholinergic premedication 62 and cardiac collapse has been reported during the procedure in case of laparoscopic tubal ligation, during CO2 insufflation vaginally 63 and during sterilisation in two cases attributed to vagal atypical reaction and to CO2 embolism 64. Most interestingly a report of cardiovascular collapse after CO2 exsufflation in a patient undergoing laparascopic cholecystectomy, The patient was 75-yr-old male, hypertensive on captopril and nadolol, rapid exsufflation resulted immediately in hypotension, bradycardia and low oxygen saturation, but responded well to treatment. The possible mechanism for this event was explained as a haemodynamic changes simulate the changes after aortic cross-clmping and release of the clamp in aortic surgery. In healthy individuals this may be compensated but the beta blocked and vasodilated patient may be unable to compensate 65. The laporoscopic procedure itself is not arrhythmogenic 66. Other reported complications are intestinal injuries, surgical emphysema, scrotal, ocular. Carbon dioxide venous embolism : Fatal 67-69 and non Fatal 70,71 . Pneumothorax 72 , pneumo-pericardium73,74 and pneumo-mediastinum 75. Tension pneumothorax also has been reported during laparoscopic cholecystectomy following trocar insertion and intraperitoneal CO2 insufflation. A congenital defect of the diaphragm (patent pleuroperitoneal canal through which the insufflated gas passes into the thoracic cavity has been suggested as the underlying mechanism 76. Many studies and reports indicated insufflation of CO2 outside the peritoneum may lead to prolonged hypercarbia and acidosis 77,78, also acute pulmonary oedama has been reported to occur after laparoscopy 79. Gastric regurgitation in 2 of 93 fasting patients undergoing elective gynaecologic laparoscopic procedures 80. Similarly, during laparoscopic cholecystectomy there are several factors which increase IAP and which predispose to regurgitation, including the initial steep head-down tilt, insufflation of intraperitoneal gas, and mechanical pressure exerted on the abdomen by the surgical team. or the anaesthetic technique 81,82. Technical difficulties in insufflation have been reported with the insertion of Veresse needle. Lower extremity neuropathy was reported as well 83. Stray current due to capacitance coupling are possible when the devices used for electro surgical endoscopy. This may add to the previous list of risk 84.
. Carbon monoxide (CO) formation during pyrolysis of tissue in hypoxic environment was studdied, it appears that after 5 minutes of electro-cautery use and reached at the end of surgery to the median level of 475 ppm (range 100-1900 ppm), although there were no significant absorption in this study but care in scavenging the gases produced by cautery is well recommended 85, and finally nitrous oxide diffusing into the peritoneal cavity insufflated with CO2 can reach a concentration in the peritoneal cavity which can support combustion of hydrogen part of the bowel gas, while the risk of methane combustion hazard has not been proven 86,87.
8. PAIN RELIEF:
This topic was reviewed recently by Alexander JI (1997)1. The patient may feel pain in the upper abdomen, lower abdomen, back or shoulder which may be evident in 63% of patients. The greatest incidence of pain in the upper abdomen. The reporting of pain by the patients is greater after the operation which it will decrease to a low level within 24 hours, but increases to second and third peak later. Visceral pain after cholecystectomy predominates in the first 24h but subsides from a peak soon after the operation, whereas shoulder pain, minor in the first day, increases and become significant on the following day. The mechanism of the pain is considered as; tearing of the blood vessels and traction on nerves and the release of inflammatory mediators during distension of the peritoneum. phrenic nerve excitation. Peritoneal inflammation. Suxamethonium may produce pain in the shoulder but its avoidance does not reduce the shoulder pain produced by the gas.
Minimal requirements of pain relief has been noticed especially if pneumoperitonium is properly evacuated 88. Opioids were used intramuscularly (im) or intravenously (iv) or patient controlled analgesia (PCA). Ibuprofen has been used effectively for outpatient patients 89. Diclofenac 50 & 100 mg iv has been used for diagnostic outpatient procedures 90,91. Local anaesthetics used in rectus muscle sheath block alone was not effective 92. Intra-peritoneal local analgesics also was not effective 93.
9. LAPAROSCOPY INPLICATIONS FOR ANESTHEESIA:
Care is indicated during monitoring of respiratory parameters including: Airway pressure plateau and peak airway pressure. End tidal CO2 and pulse oximetry. Tidal volumes and minute volume. Attention to the increased ventilatory requirement. End tidal CO2 is imperfect index of arterial level. The need for proper institution of post-operative oxygen therapy was demonstrated in human94, and in animals95.
9.1 ANESTHESIA TECHNIQUES:
. Most of the prevailing anaesthetic combinations have been employed with the emphasis on short duration, rapid recovery and mobility and freedom from postoperative nausea and vomiting.
Anesthesia for laparoscopy has been established with a broad usage of agents and techniques. General anesthesia using balanced anesthesia technique including intravenous induction agents like: thiopentone, propofol, etomidate, and inhalational agents like: nitrous oxide, isoflurane 34,96 desflurane 97 has been reported. variety of muscle relaxants including succinyl choline, mivacurium98 , atracurium 99 and vecuronium aiming at rapid recovery and cardiovascular stability 96,97. Total intravenous anesthesia using the following agents: propofol, midazolam and ketamine, alfentanil and vecuronium has been reported also for outpatient laparoscopy 100. Epidural anesthesia was considered as safe alternative to general anesthesia for outpatient laparoscopy without associated respiratory depression 101.
9.2 IMPLICATIONS FOR ANESTHESIA:
It is obvious that optimal anesthesia care is needed with the proper understanding of potential problem and to use appropriate anaesthetic techniques with proper monitoring to detect and reduce complications 25.
Due care and monitoring during positioning are needed. A close watch during the insufflation of carbon dioxide to produce pneumo-peritonium, and attention to the peak inspiratory pressure and the adequacy of ventilation, during the procedures with the use of controlled ventilation to avoid hypercarbia using capnography to monitor for it 102. Oxygen administration and use of pulse oximetry monitoring in the immedate post-operative period will add more safetey for the patients 103. Anti-emetics should be used for these kind of procedure to reduce vomiting 104. Also to reduce the possibility of inhaling gastric contents. Non-steroidal anti-inflammatory drugs NSAIDs can be used for relief of pain for ambulant patients but avoiding its use in patients with history of gastric peptic ulcers. Sicker and older patients are more likely to be subjected for such procedures so a special care can practised to improve the outcome 18.
VARIOUS ANAESTHETIC METHODS AND AGENTS USED IN LAPAROSCOPY SURGERY.
-Total intravenous anesthesia (Bailie et al 1987):
Propofol, Etomidate and Midazolam-ketamine.
-General Anesthesia (de Grood PM et al 1987):
Induction: Propofol, Etomidate and thiopentone.
Maintenance: Isoflurane-nitrous oxide, Desflurane (Vav Hemelrijck J et al 1991)- nitrous oxide, & halothane.
Anesthesia: Fentanyl, alfentanil.
Muscle relaxant: Vecuronium. Mivacurium (Ding et al 1994), atracurium.
-Epidural anesthesia (Ciofolo MJ et al 1990).