Conference Lectures
Dr. RadhikaDhanpal
Professor
Department of Anesthesiology
St. John’s Medical College Hospital
Bangalore
Anaesthesia for neonatal minimally invasive surgery
Abbreviations used : MIS: minimally invasive surgery
After the success of minimally invasive surgical techniques in adults, application in pediatric patients was the next logical step. The widespread use of these techniques in young children however, spread slowly because the surgical instruments had to be downsized, the learning curve was steep, safe and reliable anesthetic procedures had to be developed. Since 1991 whenAlaine and Holcombe reported laparoscopic pyloromyotomy and cholecystectomyrespectively its progress has accelerated rapidly and the number of procedures that are being performed is rising rapidly and is 40 at present. Increasingly, younger patients now benefit from these techniques with neonates being the latest additions. The combination of very fine devices, precise movements, clever workarounds allowed this development to take place. .
Definition: Minimally invasive surgery is the common term for a collection of surgical techniques that aim to circumvent the morbidity and limits of “Conventional” open surgery. It is also referred to Keyhole Surgery, Band – aid Surgery, Scarless Surgery and Minimal Access Surgery.
Inclusion Criteria for MIS
- No other congenital malformations
- Stable for 24 hours even if on ventilator
- SaO2> 90%, PIP < 24 cms H2O, FiO2<40%, PEEP 3-4 cmH2O
Contra – indications
- PaCO2> 60 mmHg
- pH < 7.25
- Persistent pulmonary hypertension
- Severe associated malformations
- Large defects
Risk factors for MIS
- Low pre- operative body temperature
- High variations of EtCO2
- High PIP after insufflation
- FiO2 100% needed throughout surgery
- Frequent need of volume expansion needed intra – operatively
Types of MIS being performed in Children
Neck
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Abdomen
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Diaphragm and abdominal wall
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Orthopaedics
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Chest
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Urogenital tract
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Liver and biliary tree
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Fetal Surgery
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Advantages of MIS
- Incision: Wound tension is proportional not to the length of the incision but to the square of the incisional length. The MIS incision is 1/5 of the open incision, hence infection, wound dehiscence and hernia occur less often.
- Chest wall deformity – the incision for postero lateral thoracotomy is an especially painful incision requiring long hospital stays, epidural infusions and large doses of narcotics. As the child grows, scoliosis develops because of division of latissimusdorsi and serratus muscles; ribs being resected or tight approximation of adjacent ribs.
- Intra – abdominal advantages-
- Decreased post – operative adhesions
- Better visualization of obscure structures because of high definition cameras and angled scopes helps the surgeon “move small”
- Cost benefit ratio because of shorter hospital stay
- Precision –Results are superior
- Speed – Depends on the experience of the surgeon
- Information Gain – Without open surgery or radiography, diagnosis of malrotation, appendicitis, Ladd’s band may be made and operated
- Faster recovery and decreased post operative morbidity
Disadvantages of MIS
- Cost of surgery rises disproportionately to the declining size of the patient
- Equipment is costly
- Learning curve is steep
- Small space to work in
- Tissue injury even burning
- Hypothermia – Evaporative heat loss due to CO2 insufflations
- Hypercarbia and respiratory acidosis
- Hypoxia
Newer Types of MIS
- Single port laparoscopic surgery – only advantage is cosmetic
- Minilaparoscopy – Ports are so small that they can be sealed with dermal glue. Less painful and aesthetically appealing
- Robotic surgery – More precise but no proven advantage
- NOTES (Natural orifice transluminal endoscopic surgery) through stomach, vagina, anus (pull - through), oral (oesophageal atresia)
Pre anaesthetic evaluation – The overriding goal in the pre-operative evaluation is to ascertain whether or not the patient is in the best possible condition. For thoracic and neurosurgical procedures, the anaesthesiologist must endeavour to understand the nature and location of the pathology especially with mediastinaland lung masses
Investigations: For elective procedures in healthy paediatric patients, no pre-operative laboratory testing is indicated. Routine “screening” examinations have almost no value in this population. For patients with complicated medical problems, laboratory examination should be focused on known or suspected physiologic derangements, bleeding disorder and congenital heart disease.Procedures near the great vessels should have blood available
Pre-medication: Oral midazolam 0.5-0.7 mg/kg , 10-30 mins prior to anesthesia.
- Anticholinergic such as glycopyrrolate or atropine to dry secretions, blunt cholinergic mediated airway reactivity.
- Ranitidine
- Metoclopramide or cisapride as prokinetic agents
- EMLA cream for IV access
- Albuterol and ipratroprium nebulisation for airway hyper reactivity
- Dexamethasone for patients with airway hyper reactivity and procedures which may result in post operative airway edema.
Thoracoscopy :The child presenting for thoracoscopy may vary from a healthy Day Care patient to an emergent procedure in a neonate with severe underlying systemic illness or even one on ECMO.
Anaesthetic management:Anesthesia for pediatricthoracoscopy is equipment intensive. The following will be needed
- Bronchial blockers ●Pediatric sized beanbag
- Long suction catheters ● Extra padding for positioning
- Flexible fiberoptic scope and light source ● Equipment for regional anesthesia
(Diameter 1.8 mm, can pass through a 2.5 mm endotracheal tube)
Monitoring
- ECG ●Temperature – Rectal
- NIBP ●Neuro – muscular monitor
- Pre – cordial stethoscope ●Precordial Doppler
- EtCO2 / Transcutaneous CO2 ●Trans oesophageal echocardiography.
- PAW ●Umbilical vessels may be used for arterial and
central venous access.
Induction : IV or Volatile agent (Halothane /Sevoflurane ) with O2 +Air, atracurium 0.5 mg mg/kg, fentanyl 2µg/kg. Intubation with either an
- Endotracheal tube in the trachea, two lung ventilation and CO2 insufflation into the open thorax to keep the lung down.
- Intubation of main stem bronchus with the tip of the tubeplaced just beyond carina
- Bronchial blocker for operative lung: Either a bronchial blocker orFogarty Embolectomy catheter, atrioseptostomy and PA catheters all have lumens which can be used for suctioning. The cuffs should preferably be filled with saline. This should preferably be placed outside the endo-tracheal tube. It may migrate to block the tip of the tube and hence continuous auscultation over both the lungs and monitoring inflation pressures will help identify the problem quickly.
Maintenance of anesthesia: GA with controlled ventilation Air, O2 and 0.5 – 1.0 MAC of Isoflurane to minimise effects on HPV, N2O to be avoided as it aggravates post – operative nausea and vomiting and expands emboli and air containing spaces. IV agents like barbiturates, ketamine and fentanyl may be supplemented. For obstructive airway lesions isoflurane, O2, Hemixture may be used. Ventilation with 8 – 10 ml / kg and if normocarbia is not maintained, VE has to be increased.
Ventilatory limitations to be kept in mind in neonates are
- Small caliber of the airway
- High instrument dead space
- The absorption of CO2 per unit of weight is higher in newborns and the low quantity of peritoneal fat and close proximity of the vessels and serosalsurfaces increase the permeability of the peritoneum to CO2.
If oxygenation is not maintained, PEEP 4 – 5 cms to dependent lung and CPAP 4-5 cms H2O to operative side have to be applied. As this may inflate the operative lung, CO2 at 1L/min at a low pressure of 4 mmHg can be insufflated into the open hemithorax. The venous return decreases and afterload increases with the openhemithorax. To minimize these effects, the insufflating pressure should be limited, pneumothorax should be created slowly, fluids dopamine may also be given. To minimise the effects of HPV, NO, Almitrine and Isoflurane 0.5 – 1.0 MAC may be used.
Temperature maintenance is by:
Radiant warming lights
Warm water mattress
Forced air warming blanket
Warm insufflating gases
Complications :
Hypoxia
●Confirm position of the tube ●Check if upper lobe is blocked,
●Blocker may have moved ● Apply PEEP to dependant lung and
●CPAP to operative lung ●Last resort is two lung ventilation
Hypercarbia :● Minute Ventilation, if no response ●Two lung Ventilation
CO2embolism :●Abrupt fall in PEtCO2 ●TOE can detect as little as 0.1 ml
●Precordial Doppler can detect 0.5 ml ●Durant’s position to be adopted
Bronchial injury: Blocker balloon becomes a high pressure device causing mucosal ischemia and rupture.
Evacuate the pneumothorax at the completion of the case,reverse and extubate
Post operative Analgesia is by IV opioids,α agonists at first, then oral opioids. Infiltration of trocar sites is helpful. If a caudal epidural is in place, it is useful. Intrapleural blocks intercostals blocks, stellate ganglion blocks, NSAID’s may all be used
Need for Elective Post – operative ventilation depends on
- Whether the child was on pre – operative mechanical ventilation
- Age < 3mts
- Presence of pulmonary hypertension
- Associated congenital heart disease
- Prematurity
- Associated respiratory disease
No class of surgical procedure demonstrates the advantages of team effort more than does thoracoscopic procedures in small children. By understanding the issues that each discipline faces and working together to meet the challenges as they arise, surgeons, anaesthesiologists and nurses can accomplish what heretofore had been considered impossible.
Anesthetic considerations for laparoscopy
- Dehydration must be corrected before surgery
- Many conditions may need Rapid sequence Intubation with Succinylcholine
Maintenance – A balanced anesthesia technique using inhalational agents, intravenous agents, non – depolarizing neuro muscular blockers or TIVA with propofol and remifentanil or afentanil can also be used
- When pneumoperitoneum is instituted and Trendelenburg position adopted, lung volumes decrease, especially the FRC. Pulmonary compliance decreases by 30 – 50%, airway resistance 20 – 30%, PAW, VQ mismatch, alveolar dead space, PaCO2, a – etCO2 gradient all increase . A 30 % increase in VE is required to maintain normocarbia. With uncuffed tubes, Pressure controlled ventilation is recommended.
- Good venous access above the diaphragm is obtained, if not possible, a central vein will have to be cannulated
- Fluid administration is based on the loss and haemodynamic changes
- Cardiac index ¯13%, Stroke Volume Index by 30%, Systemic Vascular Resistance increases
- Mean arterial pressure remains unchanged;Renal blood flow, Glomerular Filtration rate and Urine output all decrease.
- Intra – abdominal pressure is to be maintained around 12 mmHg
- Sub arachnoid block with 1.2 – 3.3mg Bupivacaine may be combined with GA
Monitoring – Exhaled Volume
PAW
Core temperature
TEE
PNS – if the child strains, Intra abdominal pressure goes up
Intra arterial pressure is monitored only if the case is prolonged or difficult
At the end of surgery, CO2 should be desufflated to decrease PONV and shoulder pain
In small infants with prolonged procedures, it is better to ventilate post – operatively
Causes of post – operative pain
Trocar and instrument sites
CO2 distension of abdomen
Residual CO2 irritating phrenic and vagus nerves
Visceral pain from operative site
Musculoskeletal pain from positioning
Treatment :
Patient controlled analgesia
Nurse controlled analgesia
NSAID’s morphine, Pethidine, Ketorolac, Diclofenac, Acetaminophen IM, IV, oral
Infiltration of ports with Bupivacaine or Levobupivacaine
Instillation of local anesthetic into the peritoneal cavity or gall bladder bed is not proven to be effective .
Comparison between laparoscopy and Thoracoscopy
Laparoscopy Thoracscopy
Higher FiO2 100% 58% < .01
Vascular expansion needed 25% 75% <.01
Frequencies of critical incidents 30% 60% < . 01
ENT Surgery– With Laser or cryo is performed without endotracheal intubation by insufflation of inhalational anaesthesia and either spontaneous ventilation or the use of jet ventilation supra / subgllotic at 10 – 15 psi
Minimal access fetal surgery: Endoscopic access to the fetus as a therapeutic option is a technique which has been in evolution since the 1980’s
Current indications:
●Posterior urethral valves ●Tracheal occlusion is congenital Diaphragmatic hernia
●Amniotic band ●Tracheostomy in CHAOS (congenital High Airway obstruction
syndrome )
Meningomyelocele
In the future cardiac anomalies like septal defects and PDA may be tackled
Pre – operative preparation
- Prevention of uterine hyperactivity by administration of indomethacin to the mother
- Tocolytic infusions may also be needed
- Daily ECHO for the fetus
- Placental mapping by ultrasound imaging
- Magnified airway X ray of the fetus to view airway abnormalities not seen in a normal chest x-ray especially in Congenital Diaphragmatic Hernia, Tetrology of Fallot and other cono – truncal lesions
- VACTORL abnormalities have to looked for (Vertebral, anal, cardiac, tracheal, oesophageal, renal, limb)
If the placenta is posterior, a percutaneous approach is possible ; if the placenta is anterior, a laparotomy may be necessary.
Anestheticmanagement : GA with inhalation agents for the mother. Additional agents for uterine relaxation like NTG and Terbutaline may also be used. An epidural catheter is useful. The fetus can also be given an intra – operative IM injection of long – acting NMBA and a short acting narcotic to minimize fetal stress response. The mother is positioned with the right side slightly elevated and a modified lithotomy with knees low. Sequential compression devices for the lower extremity should be applied during the pre, intra and post – operative periods.
Post – operative care for the mother
- Bed rest
- Pneumatic compression device
- Epidural analgesia if in situ
- Analgesics – narcotics at first IV, orallyafter oral intake has been resumed
- IV or SC Betamimetics
- Oral prostaglandin inhibitors
The effects of these medications on the fetus especially on the ductusarteriosus have to be monitored
Disadvantages
Pre – term labour
Premature rupture of membranes
Chorio – amnionitis
Oligohydramnios
To conclude, MIS is more than technique or technology, it is a choice both for the surgeon, and the parents. Properly applied, it may offer better information, more surgical options, shorter hospital stays, lower costs, similar or superior results.
Bibliography
- Tobias JD “Anesthetic considerations for endoscopic procedures in children” SeminPediatr Sur 1993 Aug;2 (3):190 – 4
- Eugene D. McGahren et al. “Anesthetic techniques for pediatricThoracoscopy”. Ann ThoracSurg 19995;60:927-30
- Tobias JD “Anaesthetic implications of thoracoscopic surgery in children” Paediatric Anesthesia1999; 9(2): 103 – 110
- Tobias JD “Anaesthesia for minimally invasive surgery in children” Best Pract Res ClinAnaesthesiol 2002 Mar;16(1);115-30
- Tobias JD “Anaesthesia for neonatal thoracic surgery” Best Practice and Research Clinical Anaesthesiology 2004;18(2):30 -320.
- Kalfa N et al “Tolerance of Laparoscoy and Thoracoscopy in Neonates” Pediatrics 2005;116(6):e785 –e791
- Randall M Clark “Anesthesia for PediatricThoracoscopic Surgery” In; “ Endoscopic Surgery in Infants and children” Kloes (N) M.A. Bax et al eds, Springer Publications, New York 2008:83-88
- Cindy S.T. Aun and Manoj K. Karmarkar “Anesthesia for Pediatric Laparoscopy” In: Klaas (N) M.A. Bax et al (eds) Endoscopic Surgery in Infants and children,Springer Publications, New York 2008:227-232
- Thane Blinman MD et al “Pediatric Minimally Invasive Surgery: Laparoscopy and Thoracoscopy in Infants and children.”Pediatrics 2012;130(3):539 – 549.”