Anesthesia for Laparoscopic Surgery

					Anesthesia for Laparoscopic Surgery
Intern 陳律安/蔡伯鑫 2005.7.1

Case Presentation
 





A 38 y/o man without mention of any systemic disease except HBV carrier. He suffered from RUQ abd. discomfort for 3 mouths. Abd. Pain aggravated in past 2 wks, and gallbladder stone was diagnosed by echo in 澎 湖國軍醫院 Then he went to our OPD for help.

 

No clay color stool, no tea color urine Under the impression of chronic cholecystitis, he was admitted for surgical management. Smoking: 1~2 PPD for 10 yrs, Alcohol: social intake Denied other systemic diseases. PE: Murphy’s sign: equivocal

 



Anesthesia Record
   


 



ETGA, supine position, ASA class Ⅱ Premedication: nil Fentanyl Pentothol SCC Cisatracuruim O2/Air Isoflurane Trandate 5mg

Discussion
1. 2.

3.

Hemodynamic effects Respiratory effects Conclusion

Pre-OP Evaluation
Advantage/ character of laparoscopy  Rare absolute contraindications  IICP, VP shunt, peritoneojugular shunt  Heart diseases v.s hemodynamic change  Gasless?  Body shape  Lung function test


Prepare/Premedication
NPO & NG tube  NSAID



postoperative pain  opiate requirements

Hemodynamic effects(1)


Physiological changes
 ↑SVR  ↑BP  ↓CO


↑PVR

↑Afterload and ↓preload (venous return)

 HR?  ↑Myocardial

oxygen consumption

Hemodynamic effects(2)
SVR ↑ BP ↑  mechanical & neurohumoral factors  isoflurane ; direct vasodilating drugs  CO

 If

sufficient IV volume loading (10ml/kg prior to induction of pneumoperitoneum) → ↑CO  Generous volume loading is recommended to all patients, esp. those with CAD

High-Risk Cardiac Patients
Increased afterload is a major contributor  Preload augmentation


Assessment of intravascular volume


CVP
 ↑IAP

→ ↑intrathoracic pressure → ↑CVP  CVP does not reflect the venous return precisely  Normal CVP → maybe still volume depleted

TEE :realtime  Pulmonary pressure

 ↑IAP

→ pulmonary vascular resistance

Patient position


Head-down (Trendelenburg position)
 ↑Central

blood volume and pressure  ↑Cardiac output


Head-up
 ↓Venous


return & Cardiac output  ↑Femoral venous pressure
↑risk of DVT or pulmonary embolism

Treatment of hemodynamic response: HTN


Most common: increase the depth of anethesia
 Prolonged

recovery, not recommended

Esmolol / Trandate  Nicadipine  NTG


Arrhythmia
Develop early during insufflation, but reversible  Cause

 Stretch

of peritoneum → ↑vagal reflex  Accentuated if anesthesia is too superficial  Accentuated with β-blocker  known cardiac disease or gas embolism

Arrhythmia


Management
 Interruption

of insufflation  Atropine administration  Deepening of anesthesia after heart rate recovery

Management to Cardiac diseases
     

Pre-op: echo Intra-op monitor: Aline, TEE? Gasless or laparotomy Slow insufflation / Low IAP (<15mmHg) Preload augmentation Remifentanil, vasodilating anesthetic and drugs

Discussion
1. 2.

3.

Hemodynamic effects Respiratory effects Conclusion

Pulmonary function


Mechanical factors
 ↑IAP  Elevation

of the diaphragm  Atelectesis (basal regions) → V/Q mismatch


Physiological changes
 ↑Intrathoracic

pressure & airway pressure  ↓FRC & total lung volume  ↓Thoracopulmonary compliance (30%~50%)

Patient position


Head-down (Trendelenburg position)
↓FRC, ↓compliance  Marked only in obese, elderly patients
 Atelectesis,



Head-up
 More

favorable to respiration

PaCO2 & ETCO2
 



CO2 was rapidly absorbed from the peritoneal cavity into circulation ETCO2 reaches plateau after 20-30 min → excess CO2 begins to accumulate To prevent hypercapnia and respiratory acidosis
 ↑Minute


ventilation (15-25%)

↑Tidal volume or ↑respiratory rate

 ETCO2:

35mmHg

PaCO2 & ETCO2


ETCO2 is an imperfect index of PaCO2
 ↑Dead-space


ventilation

Impaired CO2 excretion capacity (e.g., COPD, cyanotic CHD)  Acute cardiopulmonary disturbances
 PaCO2

can remain elevated despite adjusting minute ventilation to normalize ETCO2

PaCO2 & ETCO2


Monitoring
 Capnography


is mandatory

Healthy patients  No acute intraoperative disturbances
 ABG

Patients with pulmonary diseases  Hypercapnia is clinically suspected


Respiratory complications
1.
2.

3.
4.

CO2 subcutaneous emphysema Pneumothorax, pneumomediastinum, pneumopericardium Endobronchial intubation Gas embolism

CO2 subcutaneous emphysema


Cause
 Accidental

extraperitoneal insufflation  Unavoidable in procedures with intentional extraperitoneal insufflation


Pathophysiology
 Larger

absorption area  ↑PaCO2, ↑ETCO2

CO2 subcutaneous emphysema


Diagnosis
 Capnometry:

Any increase in ETCO2 after plateau  Crepitus over the abdominal wall


Management
 Stop

surgery and deflate the pneumoperitoneum  Correction of hypercapnia under controlled mechanical ventilation  Resume with a lower insufflation pressure

Pneumothorax


Causes
 Embryonic

remnants as potential channels, open when ↑IAP  Defects in the diaphragm or weak points in aortic and esophageal hiatus  Preexisting pulmonary bullae rupture


↑Minute ventilation → ↑alveolar inflation

Pathophysiology of pneumothorax
↑Airway pressure, ↓PaO2  Capnothorax

 Greater

absorption from pleural cavity  ↑PaCO2, ↑ETCO2


Pneumothorax from alveolar rupture
 ↓CO

→ ↓ETCO2

Diagnosis of pneumothorax



Continuous side-stream spirometry
 ↓Dynamic

compliance & ↑airway pressure

Auscultation of the chest  CxR

Management of pneumothorax
   

Stop surgery and deflate the pneumoperitoneum Supportive treatment
 Adjust

ventilator settings to correct hypoxemia

Confirm the diagnosis by clinical examination, and, if time permits, CxR Assess the severity of pneumothorax based on the degree of cardiopulmonary compromise

Management of pneumothorax


Capnothorax
 Avoid  PEEP

thoracocentesis unless necessary



Pneumothorax from alveolar rupture
 Thoracocentesis

is mandatory  PEEP must NOT be applied

Endobronchial intubation


Cause
 Cephalad

displacement of diaphragm → cephalad movement of carina



Pathophysiology
 ↓SpO2  ↑Plateau

airway pressure



Prevention
 Tracheal

tube should be reassessed after creation of pneumoperitoneum and position change

Gas embolism
   

Causes: Tear in a vessel or parenchymal organ Rarely with clinical manifestations, but potentially fatal TEE: 68% CO2 bubbling in the right heart chamber during LC Most common
 During

the initial insufflation  During dissection phase of the gallbladder

Pathophysiology of gas embolism
Gas lock in the vena cava and RA → ↓venous return → ↓CO → ↓ BP, ↓PaO2, ↑HR, ↑physiologic dead space  Paradoxical embolism → neurologic impairment

 Through

foramen ovale, opened by acute RV hypertension (20-30% of the population)

Diagnosis of gas embolism


Early (<0.5ml/kg of air)
 Change

in Doppler, TEE  ↑Mean pulmonary arterial pressure


Late (>2ml/kg of air)
 Tachycardia,

cardiac arrhythmias, hypotension, ↑CVP, cyanosis, EKG with right heart strain  Physiologic changes are less sensitive and reliable

Diagnosis of gas embolism
  

Doppler, TEE, or PA catheter
 Sensitive,

but low incidence preclude routine use

Pulse oximetry: hypoxemia Capnometry
 ETCO2:

Sudden increase initially, and decrease then due to cardiovascular collapse



Definite diagnosis: aspiration of gas or foamy blood from a central venous line

Management of gas embolism
   


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Stop surgery and deflate the pneumoperitoneum Position: head-down and left lateral decubitus Discontinue N2O & give 100% O2 Hyperventilation to wash out CO2 Aspiration of gas by pulmonary artery or central venous catheter External cardiac massage Cardiopulmonary bypass, hyperbaric oxygen

Discussion
1. 2.

3.

Hemodynamic effects Respiratory effects Conclusion

Intraoperative care
  

IAP < 15 mmHg Tilting < 15-20° Precipitous changes in vital signs not responding to routine management





Release the pneumoperitoneum Place the patient in the supine (or Trendelenburg) position Cautious slow reinsufflation after cardiopulmonary stabilization



Persistent significant cardiopulmonary impairment → sometimes necessary to convert to an open procedure

Postoperative care


Hemodynamic changes
 Persistent effects, esp.↑SVR  Patients with cardiac disease



Respiratory changes
 Greater
 

dysfunction and slower recovery in older, obese, smoking, COPD patients
Diaphragmatic dysfunction (due to stretching from pneumoperitoneum and CO2 irritation) Inadequate pain relief

 Prolonged

post-op mechanical ventilation  Oxygen for all patients


				
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